Linköping University Medical dissertation No. 1229

Idiopathic Sudden Sensorineural Hearing Loss Corticosteroid Treatment, the Diagnostic Protocol and Outcome

Ramesh Nosrati-Zarenoe

__________________________________________________

Department of Clinical and Experimental Medicine

Division of Oto-Rhino-Laryngology Faculty of Health Science,

Linköping University SE-58185 Linköping, Sweden

2011

© Ramesh Nosrati-Zarenoe, 2011

Cover picture: Ramin Nosrati

Published articles have been reprinted with the permission of the copyright holders.

Printed in Sweden by Liu-Tryck, Linköping, Sweden, 2011

ISBN 978-91-7393-220-2

ISSN 0345-0082

To my beloved family

Reza,

Alma and Arvid

CONTENTS

ABSTRACT................................................................................................................... 7

LIST OF ORIGINAL PAPERS................................................................................... 9

ABBREVIATIONS..................................................................................................... 10

INTRODUCTION....................................................................................................... 11

BACKGROUND ......................................................................................................... 13

AIMS ............................................................................................................................ 19

METHODS .................................................................................................................. 21

STATISTICAL METHODS ...................................................................................... 25

ETHICAL CONSIDERATIONS............................................................................... 27

MATERIAL................................................................................................................. 29

RESULTS .................................................................................................................... 33

DISCUSSION .............................................................................................................. 45 Radiological and laboratory examination.......................................................... 45 Treatment ........................................................................................................... 47 Prognostic factors .............................................................................................. 48 Suggestion for further research.......................................................................... 50

CONCLUSIONS ......................................................................................................... 51

ACKNOWLEDGMENTS .......................................................................................... 53

SVENSK SAMMANFATTNING.............................................................................. 55

APPENDIX.................................................................................................................. 67

REFERENCES............................................................................................................ 71

Abstract 7

ABSTRACT

Idiopathic Sudden Sensorineural Hearing Loss (ISSNHL) is a rapid loss of hearing caused by damage to the cochlea (inner ear) or auditory nerve. Spontaneous recovery has been seen in 32%–81%. The incidence of the ISSNHL has been estimated to be between 5 and 20 per 100,000 per year. Different theories (vascular catastrophes, immunologic damage, infections or intracochlear membrane break) about the etiology have resulted in different treatment policies. The effect of therapy is difficult to evaluate for a single physician who sees just a few patients annually.

The aim of the present thesis was: 1) to investigate the current management and treatment of ISSNHL patients in Sweden with regard to outcome, 2) to evaluate whether, in comparison to placebo, the most common drug given in the treatment of ISSNHL in any way influences the outcome, and 3) to analyze which variables such as background data, concomitant disease, audiogram shape and laboratory tests, best can predict the outcome of ISSNHL.

A national database was developed with half of all ENT clinics in Sweden participating by submitting a questionnaire for each patient with SSNHL. The questionnaire covered the patient’s background, current disorder, past and family history of different diseases, examinations, and treatment. Audiograms at the onset of SSNHL and after three months were requested.

A randomized placebo controlled multicenter trial (RCT) was performed using a modified version of the questionnaire used in the national database. Prednisolone in high tapering dosage, or placebo was given with a total treatment period of eight days. If recovery was complete, treatment stopped, otherwise medication was continued at 10 mg daily to a total of 30 days from beginning. After an initial pure tone audiogram, new audiograms were taken at three follow-up visits: day eight of treatment, after one month, and after three months.

Results from the national database showed that out of 400 patients included in the study with ISSNHL, almost 60% were medically treated, of which nearly 90% were given corticosteroids. Hearing improvement was not statistically associated with receipt of medication. 40% of all patients had an MRI or CT, where 3–4% had acoustic neuroma. 24% of the patients with ISSNHL who had hematological tests taken, had one or more pathological findings. Blood screening varied from simple routine tests to a complete analysis with such tests as HSP70, Anti-Neutrophilic Cytoplasmic Antibodies (ANCA) and Borrelia tests

In the RCT, 47 patients were randomized to Prednisolone and 46 to placebo. No significant difference of hearing recovery was observed between the Prednisolone group and placebo group at either first or final follow-up regarding the effect of treatment. Presence of vertigo had significant negative effect on hearing improvement in both groups. Inflammatory signs in laboratory work-up had a positive prognostic effect, irrespective of treatment.

Conclusion: There is no standard program for management or treatment of ISSNHL in Sweden. The diagnostic protocol varies. MRI is an underused resource to get specific

8 Abstract

diagnoses for the condition especially acoustic neuromas. Regardless of pathological findings, treatment is mainly limited to corticosteroids or no medication.

Prednisolone in customary dosage does not influence recovery of Idiopathic Sudden Sensorineural Hearing Loss. Whenever a drug or a substance is proven not to work for a specific condition, it should be withdrawn from use and the focus for research within the field turned in a new direction.

List of original papers 9

LIST OF ORIGINAL PAPERS

This thesis is based on the following papers, which will be referred to in the text by their roman numbers I - IV:

I. Nosrati-Zarenoe R, Arlinger S, Hultcrantz E. Idiopathic sudden sensorineural hearing loss: results drawn from the Swedish national database. Acta Otolaryngol. 2007 Nov;127(11):1168-75.

II. Nosrati-Zarenoe R, Hansson M, Hultcrantz E. Assessment of diagnostic approaches to idiopathic sudden sensorineural hearing loss and their influence on treatment and outcome. Acta Otolaryngol. 2010; 130:384-91.

III. Nosrati-Zarenoe R, Hultcrantz E. Corticosteroid treatment of idiopathic sudden sensorineural hearing loss. Part 1: a randomized triple-blinded placebo controlled trial. Submitted for publication.

IV. Hultcrantz E, Nosrati-Zarenoe R. Corticosteroid treatment of idiopathic sudden sensorineural hearing loss. Part 2: a meta-analysis of a RCT and the Swedish national database. Submitted for publication.

Reprints were made with the kind permission of copyright holder.

10____________________________________________________________________ Abbreviations

ABBREVIATIONS

ABR Auditory brainstem responses

AICA Anterior inferior cerebellar arteries

ANA Anti-nuclear antibodies

ANCA Anti-neutrophilic cytoplasmic antibodies

CI Confidence intervals

CRP C-reactive protein

CSF Cerebrospinal fluid

CT Computed tomography

dB HL dB hearing level

ENT Ear, nose and throat

Hb Hemoglobin

HDL High-density lipoprotein

HSP-70 Heat-shock protein 70

IgG antibodies Immunoglobulin G antibodies

IgM antibodies Immunoglobulin M antibodies

ISSNHL Idiopathic Sudden Sensorineural Hearing Loss

kHz kilohertz

LDL Low density lipoprotein

MRI Magnetic resonance imaging

OAE Otoacoustic emission

OR Odds ratio

PTA Pure tone average

RCT Randomized controlled trial

SD Standard deviation

SLE Systemic lupus erythematosus

SSNHL Sudden Sensorineural Hearing Loss

Introduction______________________________________________________________________11

INTRODUCTION

Idiopathic Sudden Sensorineural Hearing Loss (ISSNHL) involves a rapid loss of hearing that is caused by damage to the cochlea (inner ear) or auditory nerve. This hearing loss can be accompanied by tinnitus and/or vertigo.

A standard definition of ISSNHL does not exist, nor is there a standard method for reporting recovery. However, agreement has been reached with regard to the requirement for a 30 dB HL or more hearing loss in at least three contiguous frequencies1-5. The definition of “sudden” can vary from 24 hour to 72 hours in different studies 2,6,7.

No standard method exists for audiological assessment with respect to the configuration of hearing loss and hearing recovery. Hearing recovery has been reported in different categories, such as “complete recovery”, “good recovery” and “fair recovery”, but there is no agreement regarding to the actual degree of improvement indicated by each of these categories. The pattern of hearing loss has often been mixed with the degree of hearing loss8,9.

Independent of what treatment is given, spontaneous recovery can occur within a few hours to few days after onset. Complete and partial recovery is often combined when reporting spontaneous recovery, which is seen in 32%–81% of the cases2,6,10,11. A higher recovery rate has been reported for patients with hearing loss in the low frequencies than for those with loss in the high frequencies10.

Due to high rate of spontaneous recovery, not every potential patient ends up seeking help so that the incidence of ISSNHL is difficult to estimate. In 1944, De Kleyn reported an increase of ISSNHL between the years 1936 and 1942 in Amsterdam12. Since 1958, the overall incidence has been reported to be 5–20 per 100,000 per year13. Recently, there have been two epidemiological studies that have shown that the prevalence of patients seeking help has increased. One study showed an increase in Japan from 3.9 to 27.5 per 100,000 persons annually14, and another study in Germany showed a prevalence of 160 per 100,000 persons per year in the city of Dresden15.

Since the etiology of ISSNHL still remains unknown, a standardized treatment does not exist. Different theories with regard to its etiology have resulted in different treatment policies over the years in Sweden and in many other countries16-19. These treatments have included anti-stress treatment with bed rest and blockage of the ganglion stellatum in the 1950’s20, treatment with dextran 40 and other hyperosmolar hemodiluting drugs in the 1970’s21 and corticosteroid treatment since the 1980’s2.

The randomized placebo controlled trial by Wilson et al. 1980 has been the foundation for a therapy tradition, which over many years, has become internationally the most common treatment for ISSNHL. Corticosteroid dosage has been successively increased without any evidence of better effect22. Several later investigations with corticosteroids have not been able to demonstrate any specific effect even if administered through the round window23. Moreover, the Wilson study has later been criticized by Cochrane reports 2006 and 2009 as not fulfilling modern standards for RCT24,25.

12 Introduction

Due to its low incidence, its rate of spontaneous recovery and its unknown etiology, the effect of therapy is difficult to evaluate for a single physician who sees just a few patients annually. By compiling the data from a large number of patients, it was possible to identify prognostic factors and the impact of the various treatments used in Sweden. The most common treatment for ISSNHL used in Sweden was then compared to placebo with regard to treatments influence on outcome.

Background 13

BACKGROUND

The auditory system The auditory system is described as the peripheral and central auditory system. The peripheral auditory system is comprised of three components, which are the outer, middle and inner ear. The central auditory system includes the auditory pathways and auditory cortex26.

Fig. I. The peripheral auditory system.

The outer ear The outer ear consists of the pinna/auricle and the ear canal/external auditory meatus. The pinna/auricle collects and directs sound waves that are traveling through the air into the ear canal/external auditory meatus, which, in turn, transmits the sound waves to the tympanic membrane (eardrum). The ear canal forms a resonance channel that amplifies the sound pressure up to 15–25 dB in 2–5 kHz.

The middle ear The middle ear is an air-filled cavity that includes the tympanic membrane (eardrum) and the ossicular chain. The ossicular chain consists of three interconnected bones, which are the malleus27, incus (anvil) and stapes (stirrup). The malleus is attached to the tympanic membrane, and the footplate of the stapes inserts into the oval window of the inner ear. The incus is located between the malleus and the stapes. Thus, the movements of the tympanic membrane (eardrum) will set the malleus, incus and stapes into motion. Attached to the ossicular chain are the stapedius and tensor tympani muscles. The sound is not amplified evenly across the ossicular chain, and contractions of these muscles protect the inner ear by reducing the intensity of sound transmission to the inner ear.

14 Background

The inner ear The inner ear consists of two systems that function independently. These include the sensory organ of hearing, which is called the cochlea, and the organ of balance, which is the vestibular system.

The cochlea is spiral-shaped and contains fluid-filled chambers. The two outer chambers, which are the scala vestibuli and scala tympani, are a part of the bony labyrinth and are filled with perilymph. The middle chamber, which is the scala media and is also called the cochlear duct, is filled with endolymph. Both perilymph and endolymph are clear solutions that contain electrolytes and proteins, and they are chemically quite different from each other. The perilymph is rich in sodium salts, whereas the endolymph is rich in potassium salts. The cochlear duct separates the two chambers from each other by the Reissner's membrane and the basilar membrane, on which the organ of Corti lies. The third partition consists of the stria vascularis, which is a rich bed of capillaries and secretory cells that are responsible for the production of endolymph. The scala vestibuli ends at the oval window, where the footplate of the stapes sits, and the scala tympani ends at the round window. A vibration coming from the stapes into the inner ear via the oval window moves the perilymph in the scala vestibule, which, in turn, vibrates the endolymph in the scala media, the perilymph in the scala tympani, the basilar membrane and the hair bundles of the hair cells in the organ of Corti.

The organ of Corti consists of approximately 3500 inner hair cells and 15,000 outer hair cells. The hair cells lie on the basilar membrane and are covered by the tectorial membrane. The basal parts of the organ of Corti are responsible for detecting the highest frequencies that we can perceive, and the frequencies that can be detected gradually decrease as they move towards the apical parts. The inner hair cells transform the sound vibrations in the fluids of the cochlea into electrical signals. The outer hair cells amplify the low-level sounds by mechanically enhancing the motion of the tectorial membrane in order to increase the stimulation of the inner hair cells. They also add to the frequency resolution.

Fig. 2. Cross section of Cochlea.

Both the outer and inner hair cells are associated with afferent and efferent neurons. The afferent neurons, which carry information to the brain, contact mainly the inner hair cells, and the efferent neurons, which carry information back to the hair cells, connect mostly to the outer hair cells.

Background 15

The labyrinth artery is an end artery and is the sole blood vessel supplying the inner ear. The artery divides into the cochlear artery and the anterior vestibular artery. The cochlear artery further divides into the main cochlear artery and the vestibulocochlear artery. The main cochlear artery lies below the organ of Corti and has more capillaries in the apical portion of the cochlea then in the basal part. The distance between the vas spirale and the spiral border near the inner hair cells is shorter in the apical part than in the basal part28.

Glucocorticoids are one of five groups of steroid hormones that are released by the adrenal glands in response to stress. Receptors that steroid hormones bind to are ligand-activated proteins and are found in the cytosol and the nucleus. The effect of glucocorticoid is grouped into two categories namely metabolic and immunological. Cortisol is the term for glucocorticoids in humans and its metabolic effect is to increase and maintain normal concentrations of glucose in blood. By interaction with the glucocorticoid receptor, glucocorticoids can either up-regulate the expression of anti-inflammatory protein or down-regulate the expression of pro-inflammatory protein. The density of Glucocorticoid receptors varies in different tissues29. In cochlea, the spiral ganglion neurons and spiral ligament have the highest expression. The hair cells and stria vascularis have lower expression30-34.

The central auditory system A vibration that comes from the middle ear is transmuted into a neural signal in the cochlea. The neural signal transfers from the hair cells to the spiral ganglion, which is found in the spiral bony structure located centrally in the cochlea (modiolus). Axons from the ganglion cells are bundled together to form the auditory portion of the eighth cranial nerve. The auditory nerve carries the signal into the brainstem and synapses in the cochlear nucleus. From the cochlear nucleus, auditory information is split into at least two streams, which include the ventral cochlear nucleus and the dorsal cochlear nucleus. The ventral cochlear nuclear cells project to a collection of nuclei called the superior olive, which helps to determine the direction of the sound. The dorsal cochlear nucleus analyzes the quality of sound. Both streams of information proceed to the sensory thalamus and from there to the auditory cortex that is located in the temporal lobes.

Hearing impairment Hearing loss can be classified into four categories35.

Conductive hearing loss is caused by difficulties in the transmission of sound into the inner ear. A diagnosis can be made via observation of an air-bone gap on audiometry, which indicates that hearing is better when sound is transmitted in such a way that it bypasses the middle ear ossicular chain. The air-bone gap should be more than 10 dB HL.

Sensorineural hearing loss occurs without an air-bone gap, since air conduction is equal to bone conduction. A diagnosis is made through audiometry. Patients with cochlear damage have no Otoacoustic Emissions-testing (OAE), and those with auditory nerve damage fail the Brainstem Auditory Evoked Responses-testing (ABR).

16 Background

Mixed hearing loss is a combination of sensorineural hearing loss and conductive hearing loss.

Central hearing loss is caused by damage to the central pathways. The diagnosis cannot be made by pure tone audiometry, since that is often normal in affected individuals. A patient with central hearing loss usually has poor scores on their speech reception threshold or word recognition scores.

Etiologic hypotheses for ISSNHL Idiopathic diseases are ‘idiopathic’ as long as the causative agent is not known. A cause for SSNHL can be found in 10% of all cases36,37. An acute hearing loss can be a symptom caused by a multitude of known diseases within the vascular system or by different traumas and tumors within the hearing tracts38,39. Hallberg (1956) stated that ”Sudden unilateral or bilateral impairment of hearing is a symptom, not a disease.”40. Thus far, diagnosis has been based on the patient's audiogram, medical history, and physical examination, while identification of a specific cause for the sudden hearing loss is rather unusual.

Vascular theory In 1949, Rasmussen suggested vascular occlusion or ischemia as a mechanism for ISSNHL41. Vascular or hematological diseases that are associated with SSNHL, such as Buerger’s disease42, leukemia43 and sickle cell anemia44 have also been reported.

The labyrinth artery is an end artery that solely carries red blood cells and oxygen into the inner ear28. Tissue injury that results from oxygen deprivation and ischemia can occur in the cochlea within 60 seconds6. A total but temporary blood circulation blockage, can cause damage to the hair cells, the ganglion cells and the spiral ligament and can also cause neuronal loss and an alteration of the tectorial membrane after 30 minutes. This damage is irreversible even after the blood flow is restored45. The labyrinth artery is extremely vulnerable to blood pressure oscillation and abnormalities in blood flow46. Blood flow has an inverse relationship with blood viscosity47. Low blood flow causes anoxia due to hyperviscosity, which results in cochlear hypofunction and the inability to maintain cochlear metabolism48. A correlation between ISSNHL and blood viscosity has been shown49-51.

Different treatments regimes for ISSNHL, such as fibrinogen apheresis52, Rheopheresis53, dextran infusion54, hyperbaric oxygen55 and pentoxifylline56, have been developed in response to this vascular theory. There is evidence both to support and refute such treatment54-58.

Immunologic theory McCabe (1979) was the first to suggest autoimmunity as a cause of SSNHL, based upon clinical data, pathological findings in autoimmune tests and positive response to steroid therapy59. Hearing loss may be a consequence of local autoimmune processes within the inner ear60,61 or of systemic autoimmune diseases, such as Cogan’s syndrome62, Wegener’s granulomatosis63 and systemic lupus erythematosus (SLE)64.

Background 17

Although the inner ear was initially considered as an immunologically privileged organ, it is capable of producing a strong immune response. The presence of antibodies against antigens in the inner ear and the formation of immune complexes in the stria vascularis, endolymphatic sac and ducts support the immunologic theory65-67. Autoimmunity can cause damage to the cellular components of the organ of Corti and affect the stria vascularis and spiral ligament. Autoimmunity can also cause dysfunction of the endothelial cells and fibrocytes II, which leads to the impaired diffusion of K+ through marginal cells to the endolymph fluid. This in turn can affect the supporting cells of the organ of Corti, which precedes a late effect upon the hair cells68. The existence of glucocorticoid receptors in the stria vascularis and supporting cells also suggests their role as immune targets in the inner ear69.

Treatment of ISSNHL with corticosteroids was the result of this immune theory. Since this therapy was first used in the 1980’s, there have been many studies on the impact of corticosteroids on SSNHL2,10,70-73. However, the only two randomized, double-blinded, placebo-controlled studies (19802, 200110) with low power showed contradictory results.

Infectious theory Herpes zoster that causes sensorineural hearing loss was first reported by Hunt in 190774. SSNHL has also been reported to be caused by known infectious diseases, of both bacterial and viral origins, such as by Borrelia and Syphilis75,76, the mumps77,78 and rubella79,80.

Both an acute and latent viral attack may damage the inner ear and cause hearing loss81. Upper respiratory infection82, as an example of an acute viral infection, and members of the herpes virus family83, as an example of latent infections, have been proposed to cause SSNHL. Virus infection can damage the organ of Corti, the ganglion cells, the nervous fibers, the tectorial membrane and the stria vascularis84.

Two antiviral drugs, acyclovir and valacyclovir, are used to treat SSNHL as a result of this theory4,85. However, the four published randomized, placebo-controlled clinical studies that used acyclovir and valacyclovir did not show any benefit for the treatment of ISSNHL3-5,86.

Membrane breaks Rupture of the oval or round window can cause loss of the perilymph and result in pressure alteration between the chambers that contain perilymph and endolymph87,88. There have been studies on the temporal bones that support this theory89,90. The membrane break does not happen spontaneously, but rather occurs after a sudden pressure alteration in the middle ear that can be caused by head injuries, barotraumas or intense physical exercise40,91. The fact that many of these patients report hearing loss upon awaking6 and that not all individuals with high intracranial and intra-abdominal pressure, such as women in childbirth or weight lifters, experience SSNHL argues against this theory. In addition, not all of the temporal bones studies found evidence of active or healed ruptures of the oval or round window, basilar membrane or Reissner’s membrane81,84,92.

18 Background

Surgery with the intention to repair oval or round window perilymph fistulae combined with strict bed rest has been used in cases of ISSNHL with a history of recent trauma or barotrauma93,94.

Genetic Theory Hearing loss can be inherited. Wilde (1853) was the first to report the genetic cause of congenital deafness95. Epidemiological data about postlingual hereditary hearing loss are still unknown. Genetic hearing loss divides into two categories, Syndromic hearing loss and Nonsyndromic hearing loss. Two-thirds of all genetic hearing losses are nonsyndromic hearing loss meaning “without other clinical findings”. Seventy percent of all genetic hearing losses are recessive hearing loss, fifteen percent are dominant and the remaining fifteen percent are other form of inheritance96,97.

Many genes whose mutation causes nonsyndromic hearing loss have been identified within the last few years. WFS1exon 8, connexin 26, 30 and 31 are genes which have been identified in stria vascularis, basal membrane, spiral limbus and spiral ligament98,99.

Very few studies are done about the heredity of ISSNHL. Two papers were published 2010 on the subject100,101. Gäckler et al., found more individuals with family history of SSNHL among those who themselves had experienced SSNHL100. In the second paper, the researchers were looking for a difference in gene mutation between SSNHL patients and healthy volunteers, but found none101.

Aims 19

AIMS

The general objectives of this thesis were to find predictive factors for hearing recovery, to investigate the treatment policy of ISSNHL in Sweden and to evaluate the efficacy of these treatments on hearing recovery in comparison to placebo.

Paper I

To analyze which variables, such as background data, concomitant disease, audiogram shape and laboratory tests, can best predict the outcome of ISSNHL.

To investigate the treatment policy of ISSNHL in Sweden.

To evaluate the effects of treatments on outcomes.

Paper II

To explore the different diagnostic test batteries for ISSNHL, that are currently used in Sweden.

To evaluate if and how, positive diagnostic findings result in treatment modifications.

To investigate whether such treatment modifications influence the outcome of ISSNHL.

Paper III

To evaluate whether, in comparison to placebo, corticosteroids (Prednisolone) used in high tapering dosage in any way influence the outcome of ISSNHL.

Paper IV

To analyze a larger patient group by meta-analysis of data from the RCT together with corresponding material drawn from the Swedish national database for ISSNHL.

Methods 21

METHODS

Paper I and II The first two publications (I, II) in this thesis are based on data from a national database in Sweden for sudden sensorineural hearing loss.

Swedish national database for SSNHL The database began gathering data from patients with SSNHL in winter 2002–2003. Approximately half of all ENT clinics in Sweden have been contributing data to the database.

To build the database, a questionnaire was developed that covered the patient’s past medical history, potential precipitating events that preceded the SSNHL, traumas, family history of different diseases, especially hearing loss, the current disease, the diagnostic protocol including laboratory, radiological and further audiological examinations and all other treatments. The time course of the hearing loss’s onset and associated symptoms, such as tinnitus and vertigo, were also requested. The questionnaire included the results of an ENT examination. Information on radiological investigations (MRI or CT), laboratory work-ups and the use of BRA or a vestibular work-up were requested. This information request was phrased in general terms so as not to influence the doctor's own diagnostic practices on their decision-making process. The questions with regard to treatment included the use of corticosteroids, antiviral therapy, rheological treatment or “other” drugs, and prescription of rest or surgery of a suspected fistula. In the case that pathological test results were performed, the complete lab-sheet for that patient was requested. See Appendix I.

For each patient, after informed consent, a questionnaire was completed by the otorhinolaryngologist, and two audiograms were requested—one to have been taken during the first visit to the ENT clinic due to the symptoms of SSNHL and the other taken after three months. When available, a pure tone audiogram was requested for patients known to have a prior diagnosed hearing loss before onset of SSNHL.

Paper III A randomized triple-blind1 placebo-controlled multicenter trial on the effect of corticosteroids on ISSNHL was performed between January 2006 and September 2010. Fourteen public otorhinolaryngological centers in Sweden were successively enrolled and each center contributed for 1 to 4.8 years.

Patients asked to participate were those aged 18–80 years, presenting with sudden onset of hearing loss developing within 24 hours, and without any known etiology (no earlier or present ear disease). The pure tone average in the affected ear of the three contiguous frequencies most affected should be ≥30 dB HL. Enrollment and treatment was to be started within 7 days from onset. Exclusion criteria were the

1 Triple-blind trial is a trial in which neither the subject, the person administering the treatment nor the person evaluating the response to treatment knows which treatment a particular subject is receiving.

22 Methods

common medical reason for not using corticosteroids: pregnancy, diabetes, chronic infections, peptic ulcer, uncompensated heart disease, recent surgery, or psychiatric disease. The patients' ordinary medication for concomitant disease was permitted except vascular, antiviral or corticosteroid treatment.

A case report form (CRF) was collected for each patient. The CRF consisted of a questionnaire, audiograms, information on radiological investigations (MRI or CT), laboratory work-ups, brainstem response audiometry (BRA) and vestibular work-up, according to the praxis at the different clinics, and information on adverse events and/or serious adverse events. The questionnaire was a modified version of one used for the Swedish database for ISSNHL (see Sppendix II). After an initial pure tone audiogram, new audiograms were taken at three follow-up visits: day eight of treatment, after one month, and three months. In cases where patients were known to have prior diagnosed hearing loss, a copy of any available previous audiogram was included in the CRF.

All patients received written information about Sudden Sensorineural Hearing Loss, the aim of the study and instructions for taking the drugs. Prednisolone as 10 mg capsules, or placebo was given as a single dose of 60 mg daily for three days; the dose was then reduced by 10 mg per day, with a total treatment period of eight days. If recovery was complete (complete recovery=difference between the initial audiogram and audiogram at the follow-up <10 dB), treatment stopped, otherwise medication was continued at 10 mg daily to a total of 30 days from beginning. Follow-up visits were scheduled for day eight ± one day, 1 month and 3 months after randomization. If recovery was complete at day eight, the next follow-up was at 3 months.

Paper IV Meta-analysis was used to strengthen and confirm the results from the randomized triple-blind placebo controlled clinical trial on the effect of corticosteroids on ISSNHL (Paper III). The material from the RCT (Paper III) was augmented with corresponding data drawn from the Swedish national database for SSNHL.

The patients included in the analysis had been treated with Prednisolone, treated with placebo or received no treatment. The patients from the database were selected if they had received the same or equivalent treatment as in the RCT, which was Prednisolone as 10 mg capsules as a single dose of 60 mg daily for three days, thereafter reduced by 10 mg per day, with a total treatment time of at least eight days. The control group from the RCT was the placebo treated patients, with audiograms at the start and after 3 months. The control group from the database was those who had not received Prednisolone or other specific treatment, but been examined with audiograms at the initial visit and after 3 months.

Assessment of hearing loss and hearing recovery Sudden Sensorineural Hearing Loss was defined as a hearing loss of at least three contiguous frequencies between 0.125 kHz to 6 kHz, with a mean of 30 dB HL or more and that occurred within 24 hours.

Methods 23

The hearing loss was characterized by a comparison of the audiogram taken at the first visit after onset of SSNHL to an audiogram that was taken not more than two years before the acute hearing loss. If no previous audiogram was available, hearing was compared to the non-affected ear in its present state.

Four frequency regions were created to describe the hearing loss:

Low frequency region: Pure-tone average (PTA) of low frequencies (125, 250, 500 Hz) > PTA of mid

frequencies (1000, 1500, 2000 Hz) and high frequencies (3000, 4000, 6000 Hz) by at least 10 dB.

Hearing loss in the low and mid frequencies – PTA of low frequencies > PTA of mid frequencies with a difference less than 10 dB.

Mid frequency region: PTA of mid frequencies > PTA of low- and high frequencies by at least 10 dB.

Hearing loss in the low and mid frequencies – PTA of mid frequencies > PTA of low frequencies with a difference less than 10 dB.

High frequency region: PTA of high frequencies > PTA of low- and mid-frequencies by at least 10 dB.

Hearing loss in the mid and high frequencies – PTA of high frequencies > PTA of mid frequencies with a difference less than 10 dB.

Flat loss: The differences between the PTA for all three frequency regions were less than

10 dB.

The audiogram taken at the first visit and the audiogram obtained three months after the onset of SSNHL were compared with respect to the PTA, characterizing the loss to determine the degree of hearing recovery and remaining hearing loss (Table I).

24 Methods

Table I. Hearing improvement and remaining hearing loss after recovery.

Improvement

Large improvement >30 dBModerate improvement 10 – 30 dBNo improvement ± 10 dBWorsening >-10 dB

Hearing loss after recovery

No remaining hearing loss Difference between initial audiogram and audiogram at the follow-up <10 dB

Partial recovery

The difference ≥10 dB and the improvement ≥10 dB

No regress The difference ≥10 dB and the improvement <10 dB

Categorization of laboratory tests The pathological results of laboratory tests were categorized by one or more pathological values prior to analysis.

“Arteriosclerosis associated variables”: LDL-cholesterol/HDL-cholesterol ratio>3, Total cholesterol >5 mmol/L and C-reactive protein (CRP) >3 mg/L in patients with or without earlier known cardiovascular disease.

“Inflammation/infection”: CRP >10 mg /L, Erythrocyte sedimentation rate >20 mm, Leukocyte count >10 x 109 ml/L, Hemoglobin count (Hb) <120 g/L, Thrombocyte count >150 x 109 ml/L and Borrelia tests “positive” (IgG antibodies and IgM antibodies) in patients with or without ongoing clinical infection.

“Autoimmune variables”: HSP-70, Cardiolipin, Antiphospholipid, Anti-Neutrophilic Cytoplasmic Antibodies (ANCA) and Antinuclear antibodies (ANA) “positive”.

Statistical methods 25

STATISTICAL METHODS

Statistical analysis was performed using Minitab software, version 13.32 for Windows, for Paper I, version 15 for Windows, for Paper II and version 16 for Windows, for Paper III and IV.

Descriptive statistics were used in all four papers to show the characteristics of the subjects. The data was expressed as the number of cases and percentage. Parametric data was expressed as mean ± standard deviation65.

Paper I and II Ordinal/Ordered logistic regression was used for all analyses with regard to hearing recovery. This method performs a logistic regression on an ordinal response variable (categorical variables that have three or more possible levels with a natural ordering) with the help of both continuous and categorical predictors.

The estimated probability for hearing improvement and no remaining hearing loss in relation to the prognostic factor, the frequency regions (low, mid, high and “flat loss”) and the frequency regions (low, mid and high) in relation to the number of days from the onset of ISSNHL was expressed as an odds ratio (OR) and 95% confidence intervals (CI).

Seasonal variance and gender differences with regard to age distribution, the presence of tinnitus and/or vertigo, the comparison between treatment options and laboratory tests, the interval between the onset of hearing loss and the first visit to the ENT clinic and the pure-tone average between different frequency regions were performed using χ2-test. The level of significance was set at p<0.05.

Paper III and IV The analyses of primary and secondary endpoints were performed according to modified Intention-To Treat (modified ITT) and Per Protocol (PP) with comparisons of pure tone audiograms.

Multiple regression was used with selected variables (age, heredity for hearing loss, vertigo, tinnitus, time from onset of SSNHL to first ENT visit, prescribed rest or sick leave, affected frequency regions) which were forced into the model together with Prednisolone and placebo. The first step in the multiple regression analysis was to study interactions between treatment and some selected variables The interactions studied were between treatment & age, treatment & time from onset of SSNHL to first ENT-visit, treatment & affected frequency regions, treatment & baseline pure tone average for the affected frequencies. The goal was to see if any of the selected interactions had a significant covariance with recovery. Interactions, that were not significant, were thereby removed from further analyses.

The second step in the multiple regression analyses was to include variables with stepwise forward method if p<0.05 to see if any single variable had a significant covariance with recovery. Three dummy variables were created out of the four categories of frequency regions and used to indicate the absence or presence of some

26 Statistical methods

categorical effect that might be expected to shift the outcome. These three dummy variables were not tested individually in the stepwise forward process; the choice was between including none or all (partial F-test).

A single-sided null-hypothesis was used in testing the effect of Prednisolone and placebo, since a deterioration in hearing due to corticosteroids was not expected:

H0 = the efficacy of Prednisolone on recovery ≤10 dB H1 = the efficacy of Prednisolone on recovery >10 dB

For the other variables, double-sided null-hypothesis was tested that the variable had no effect on recovery.

A value of p<0.05 was used for all tests to indicate statistical significance.

Ethical considerations 27

ETHICAL CONSIDERATIONS

Paper I and II The Medical Research Ethic Committee of Linkoping’s University, Sweden (registrations number 02-337) approved the database. Participants were given oral information about the database by their local ENT doctors. A written informed consent was not requested, as there was no intervention that was performed and as the participant’s identity (security number) was not reported in the database.

The data were handled confidentially. No more than the participant’s birth date and gender were provided on the questionnaires, audiograms and requested lab-sheets.

Paper III The study, EudraCT 2005-001487-32 was approved by the regional ethics review board and Swedish Medical Products Agency in accordance with the Declaration of Helsinki and good clinical practice guidelines.

All patients received written information about Sudden Sensorineural Hearing Loss, the aim of the study and instructions for taking the drugs.

A case report form (CRF) was collected for each patient. The data were handled confidentially. The CRFs were coded with the number of study drug bottle, the participant’s birth date, gender and the name of the clinic.

Material 29

MATERIAL

Paper I Three hundred patients with acute hearing loss who had initially received the diagnosis of “Sudden deafness/Sudden Sensorineural Hearing Loss” by their ENT-doctor, were included in the Swedish national database for SSNHL.

Of the three hundred patients in the database, ninety-two either had conductive hearing loss, Mb Ménière, other known disorders of the inner or middle ear, a hearing loss less than a 30 dB HL, less than three contiguous frequencies involved or a hearing loss that occurred over more than a 24-hour period. These ninety-two individuals were excluded from analysis. See Table II.

Paper II Four hundred patients (three hundred from Paper I and one hundred additional patients) who were initially diagnosed with SSNHL and, thereby, reported to the database for SSNHL were evaluated.

Table II. Final diagnosis after examination for patients initially reported as SSNHL (n=92).

Diagnoses Number

Acoustic neuromas 5

Trauma acoustic trauma 2 head trauma 2

trauma after water irrigation of the ear

2

barotraumas 3

Subdural hematoma 1

Myeloma 1

Mb Ménière 5

Hydrops 1

Progressive hearing loss 1 Bleeding in Pons (infarct at the root entry zone)

1

Transient ischemic attacks 1

Coronary disease 3

Did not fulfill the criteria Hearing loss less than 30 dB HL 44 for SSNHL Hearing loss did not occur

within 24 hours20

30 Material

Paper III One hundred and three patients with ISSNHL were included randomized evenly to treatment with either Prednisolone or placebo. Ten patients were excluded from the analyses, four of them in the treatment group and six in the placebo group. See Fig. III.

Ninety-three patients were analyzed by modified Intention-To Treat (modified ITT) forty-seven received Prednisolone and forty-six placebo. For eight of ninety-three patients, the hearing loss was evaluated by comparison of an audiogram taken within two years before the ISSNHL. Six of these had been treated with placebo.

Eighty-seven out of ninety-three patients who took the study drug according to the protocol under the first eight days of the treatment period were analyzed by PP; forty-five belonged to the treatment group and forty-two placebo. Fourteen of those eighty-seven patients either should have continued taking the study drug up to 30 days or did continue, but not in accordance with the protocol.

Seventy-three out of ninety-three patients who did take the study drug according to the protocol were analyzed as Total Per Protocol (total PP); thirty-eight belonged to the treatment group and thirty-five placebo.

Paper IV A total of one hundred ninety-two patients were analyzed, eighty-seven from the RCT and one hundred and five from the Swedish national database.

Ninety-nine of the total one hundred ninety-two had received Prednisolone and ninety-three placebo or no treatment.

The hearing of each patient was evaluated at the first visit at the ENT clinics and after three months.

At the final follow-up, audiograms were missing for two patients in Prednisolone group (RCT), one patient in corticosteroid group (the Swedish national database) and two patients in the no treatment group (the Swedish national national database).

Material 31

FIG

. III

. TR

IAL

PR

OF

IL

Fig

. III

. Tri

al p

rofi

le.

Results 33

RESULTS

Paper I The aim of Paper I was to analyze which variables best can predict the outcome of ISSNHL, to investigate the treatment policy of ISSNHL in Sweden and to evaluate the effect of treatments on outcome.

None of the patients in the Swedish national database were bilaterally affected.

Of three hundred patients reported to the database, two hundred and eight have been evaluated according to the defined criteria for ISSNHL

Descriptive data for the two hundred and eight patients with ISSNHL (age range 15–87 years, mean 57) are presented in Table III. All two hundred and eight patients had a physical examination, 68% had laboratory work-up, and 37% had MRI. The time between onset of ISSNHL and the first visit at the ENT clinics varied, with a mean of 16.4±31.5 days.

T V

able III. Profiles of the ISSNHL patients (n=208).

ariables Numb (%

er )

Gender Female 98 (47) Male

Age Mean ± SD (years) 56.1 ± 16 Range (years) 15 - 87

Affected ear Left 96 (46) Right

Prevalence of associated Tinnitus 107 (51.4) symptoms

Vertigo With nystagmus 1 (0.48) Without nystagmus 7 (3.4) No info. about nystagmus 1 (0.48)

Tinnitus and vertigo With nystagmus 10 (4.8) Without nystagmus 38(18.3) No info. about nystagmus 7 (3.4)

No info about tinnitus or vertigo 1 (0.48) No associated symptoms 36 (17.3)

Interval between onset of Median (days) 5 hearing loss and first visit at the ENT clinics

Range (days) 0 - 212

110 (53)

112 (54)

All variables in the questionnaire (Appendix I) were analyzed using ordinal logistic regression in order to look for interactions with hearing recovery and remaining hearing loss as dependent variables.

34 Results

Independent of treatment or no therapy, “Heredity for hearing loss” and older age were significantly associated with outcome. “Heredity for hearing loss” was associated with a significantly lower odds for improvement, with an odds ratio of 3.02 (95% CI 1.34–6.80, p=0.008), but was not associated with the remaining hearing loss. An older age was related to a reduced chance of both improvement of hearing in dB (OR 1.05, 95% CI 1.03–1.08, p=0.000) and the remaining hearing loss (OR 1.03, 95% CI 1.0–1.05, p=0.008).

Hearing loss in the low frequency region occurred in 42% of all cases, hearing loss in the mid frequency region in 26%, hearing loss in the high frequency region in 30% and 3% had a “flat loss”. The reported number of patients with “flat loss” was too low for statistical analysis (n=6); their hearing improved partly or totally irrespective of treatment (Table IV). Patients with hearing loss in the mid frequency region had a significantly higher chance for improvement when compared to those with hearing loss in low (p=0.000) or in high frequency region (p=0.000), if they visited an ENT clinic the same day as the onset of ISSNHL. The probability for improvement of the hearing loss decreased with number of days to ENT visit regardless of the frequency region.

Total or partial recovery for patients with hearing loss in mid frequency region was significantly more likely when compared to those with hearing loss in low (p=0.002) or high frequency region (p=0.014), if they visited an ENT clinic the same day as the onset of ISSNHL. The probability for no remaining hearing loss decreased with number of days before the first visit regardless of the frequency region.

T

P

able IV. Treatment and outcome for patient with “flat loss” (n=6).

atient No. Treatment Improvement Hearing loss after recovery

1 Prednisolon 60 mg/day Large No remaining hearing loss

1 No medical treatment Moderate Partial recovery

1 Prednisolon 60 mg/day Moderate Partial recovery

1 Prednisolon 60 mg/day Moderate Partial recovery

1 No medical treatment Large No remaining hearing loss

1 Prednisolon 80 mg/day Moderate Partial recovery

Corticosteroid therapy was used for one hundred and five (50%) of the total two hundred and eight patients and ninety (44%) received no medical treatment. Of the remaining eleven patients, three received antiviral therapy and five received antibiotics. In all, 38% of the patients treated with corticosteroids had a large improvement (>30 dB) and 34% had moderate improvement (10–30 dB) compared with 28% with large and 36% with moderate improvement among those who were not medically treated. The differences were not significant.

The main corticosteroid used was Prednisolone (80%). The dosage, duration of treatment and tapering schedule varied from 80 mg to 25 mg per day for five days to four weeks. No significant difference in outcome was seen as regards the dosage

Results 35

given. Among those who were treated with Prednisolone, 68% received high dose (>50 mg/day) and 32% received low dose (≤50 mg/day). Large improvement (>30 dB) was noticed among 40% of patients treated with high dose (>50 mg/day) Prednisolone and moderate improvement (10–30 dB) among 33% compared to 30% showing large and 37% moderate improvement among those who were treated with low dose (≤50 mg/day). See Table V. The differences between the groups were not significant.

36 Results

Paper II The aim of Paper II was to explore the different diagnostic test batteries for ISSNHL that are currently used in Sweden, to evaluate if and to what extent, positive diagnostic findings result in treatment modifications and to investigate whether such treatment modifications influence the outcome of ISSNHL.

Of four hundred patients reported to the database, three hundred were evaluated as suffering from ISSNHL. Descriptive data on the three hundred patients evaluated as suffering from ISSNHL are presented in Table VI.

One hundred and fifty-eight (40%) of the four hundred patients with SSNHL had an MRI or CT, and twenty-two had pathological findings. Out of the twenty-two with pathological findings, ten patients had accidental findings that were not connected to the hearing tracts and thereby were defined as ISSNHL. Out of remaining twelve patients: five had acoustic neuroma, one had subdural hematoma, one had a pons infarction and five had different vascular abnormalities that might have had a possible connection to SSNHL. The five individuals who had different vascular abnormalities had all a low frequency hearing loss (Table VII).

No significant association was found between pathological MRI-findings and either hearing recovery or remaining hearing loss for the patients with ISSNHL.

T V

able VI. Profiles of the ISSNHL patients (n=300).

ariables Number (%)

Gender Female 146 (49) Male 154

Age Mean ± SD (years) 57.4 ± 16 Range (years) 8 - 87

Affected ear Left 141 (47) Right 159

Prevalence of associated Tinnitus 149 (49.7) symptoms

Vertigo With nystagmus 1 (0.33) Without nystagmus 11 (3.7) No info. about nystagmus 1 (0.33)

Tinnitus and vertigo With nystagmus 16 (5.3) Without nystagmus 49 (16.3) No info. about nystagmus 11 (3.7)

No info about tinnitus or vertigo 1 (0.33) No associated symptoms 61 (20.3)

Interval between onset of Median (days) 5 hearing loss and first visit at the ENT clinics

Range (days) 0 - 498

(51)

(53)

Results 37

Hematological tests were taken in two hundred and fifty-eight (65%) cases of the total four hundred. The blood screening varied from simple routine tests to a complete analysis (CRP, Hb, HSP70, ANCA tests, and Borrelia tests), covering most hypotheses concerning SSNHL (e.g., infections, vascular catastrophes, autoimmune disease or membrane rupture).

Of the three hundred patients who were classified as having ISSNHL, one hundred ninety six had one or more laboratory tests taken, and forty-seven (24%) of these had one or more pathological findings.

The group categorized as having pathological “arteriosclerosis-associated variables” (n=13) was significantly older than those with normal laboratory tests (n=148), 65 ± 11 years and 56 ± 17 years, respectively, p=0.016. The twenty-seven patients with ”inflammation markers” were of the same age as those with normal laboratory tests. Of these, fifteen had positive Borrelia findings. Seven patients were regarded as having pathological “autoimmune variables”. No age difference was seen between those with pathological “autoimmune variables” and those with normal laboratory tests.

There was no association between any of the laboratory tests and either hearing improvement or remaining hearing loss, even when the tests were evaluated separately or after the tests were compared to those who had normal laboratory findings.

Table VII.

Patients with low frequency loss and vascular changes as possible cause of ISSNHL shown by MRI (n=5). Treatment and outcome.

Patient Diagnosis Treatment Hearing recovery

1 ISSNHL Corticosteroids + Antiviral therapy No improvement

2 ISSNHL Corticosteroids No improvement

3 ISSNHL Corticosteroids Moderate improvement

4 ISSNHL Prescribed rest Moderate improvement

5 Myeloma Cytostaticum Moderate improvement

Medical treatment was given to one hundred eighty-two (61%) of three hundred patients with ISSNHL. Of these, one hundred sixty-six patients were given corticosteroids either as single treatment or in combination with antiviral therapy, antibiotics or blood thinning therapy (acetylsalicylic acid). Three patients were only given antiviral therapy, six others only antibiotics, two were only given acetylsalicylic acid, and five received various other drugs. Ninety-six patients received no treatment at all.

Medical treatment had no significant correlation with either hearing improvement or remaining hearing loss

Seventy-seven of three hundred patients with ISSNHL (26%) were prescribed “to rest” or “to stay home on sick leave” for up to four weeks; this was the only treatment for twenty-two of these patients. Patients who had been prescribed rest or been on sick

38 Results

leave during the first period of the disease had higher odds for hearing improvement (OR 0.46, 95% CI 0.27 – 0.79, p=0.005), regardless of any other treatment.

40% of the patients had their hearing loss in the low frequency region, 28% in the mid frequency region, 23% in the high frequency region and 9% had a “flat loss”. Patients with hearing loss in the mid frequency region had significantly higher odds for hearing improvement compared to those in the groups with a hearing loss in the low frequency region, the high frequency region or a “flat loss”.

The odds for a residual hearing loss was lower for patients with hearing loss in the mid frequency region when compared to those with a hearing loss in the low frequency region (OR 0.45, 95% CI 0.26 – 0.78, p=0.005), the high frequency region (OR 0.31, 95% CI 0.16 – 0.58, p=0.000), or a “flat loss” (OR 0.43, 95% CI 0.18 – 1.01, p=0.05).

All variables in the questionnaire were analyzed using ordinal/ordered logistic regression looking for interactions with hearing recovery and remaining hearing loss as dependent variables. Three factors were significantly related to outcome independent of treatment or no therapy, namely “Heredity for hearing loss”, age, and presence of vertigo at onset; for details see Table VIII.

Tre

able VIII. Outcome measures after ISSNHL with respect to hearing improvement and maining hearing loss using ordinal logistic regression (n=300).

Hearing improvement Remaining hearing loss Variable

OR 95% CI p-value OR 95% CI p-value

Increase of age 1.03 1.01 – 1.05 0.000 0.98 0.96 – 0.99 0.001

Vertigo at onset 1.77 1.06 – 2.95 0.03 0.40 0.24 – 0.67 0.000

Heredity for hearing loss 2.08 1.10 – 3.94 0.02 ns ns ns

Prescribed to rest 0.46 0.27 – 0.79 0.005 ns ns ns OR=Odds Ratio, CI= Confidential Interval

Results 39

Paper III The aim of Paper III was to compare treatment with corticosteroids (Prednisolone) used in high tapering dosage to treatment with placebo with respect to influence on the outcome of ISSNHL.

Ninety-three patients were analyzed by modified ITT; forty-seven received Prednisolone and forty-six placebo (Fig. III). Audiograms were missing for four of them at final follow-up. Those missing were not included in the analysis—two had gotten Prednisolone. The baseline characteristics data and hearing improvement of ninety-three patients included in the modified ITT analyses are described in Table IX.

Of the ninety-three patients in modified ITT analysis, fifty had one or more laboratory tests taken. One or more pathological findings were discovered in seventeen of twenty-six patients with laboratory work-up in the Prednisolone group compared with nine of twenty-four in the placebo group. Almost all of the patients with abnormal findings had “inflammations markers”.

MRI or CT was done on forty patients in modified ITT analysis. Abnormal findings were seen in thirteen of twenty-two patients with MRI or CT in the Prednisolone group compared with ten of eighteen in the placebo group. The majority of the findings were different vascular abnormalities. Acoustic neuroma was found in one patient.

Variables

Table IX. Baseline characteristics and hearing improvement of 93 patients included in a modified Intention-To Treat analysis.

Prednisolone (n=47)

Placebo (n=46)

p-value

Gender Female 23 17 Male 24 29

0.297

Age Mean ± SD (years) 56.8 ± 12.7 53.8 ± 13.5 0.281 Range (years) 26 - 80 26 - 79

Affected ear Left 25 22 Right 22 24

0.680

Initial pure tone Mean ± SD 66.2 ± 21.2 63.5 ± 16.9 0.507 average for the affected frequencies (dB HL)

Range 32 – 110 32 – 100

Improvement at day eight (dB)

Mean ± SD Range

25.5 ± 27.1-40 to +87

26.4 ± 26.2-32 to +75

Improvement at day ninety (dB)

Mean ± SD Range

39 ± 20.1-5 to +87

35.1 ± 38.3-17 to +84

Affected frequency Low frequency region 14 13regions Mid frequency region 22 24 High frequency region 10 6 “Flat” loss 1 3

0.573

Prevalence of Tinnitus 30 38 0.061 associated symptoms Vertigo 11 14 0.49 No associated symptoms 10 6 0.411

Mean ± SD 3 ± 1.9 3,2 ± 2.3 0.660 Median 3 2

Time from onset of SSNHL to the first at

0

the ENT clinics Range 0 - 7 0 - 7

40 Results

Effect of treatment at the first and final follow-up (day eight and ninety) No significant difference of hearing recovery was observed either at day eight or day 90 between the Prednisolone group and placebo group regarding the effect of treatment.

The estimated treatment efficacy at the first follow-up was –3.1 dB (p=0.563) and –0.83 dB (p=0.887) at day 90 for the ninety-three patients in modified ITT analysis. (See Table X)

For PP analysis, the estimated treatment efficacy at the first follow-up was –2.48 dB (p=0.662) and for the total PP analysis –2.91 dB (p=0.675), meaning those patients receiving Prednisolone recovered insignificantly less than the placebo group.

The estimated treatment efficacy at the final follow-up for PP analysis was –0.18 dB (p=0.976) and for the total PP analysis –0.06 dB (p=0.994).

Total recovery occurred in twenty patients after eight days of medication with the study drugs, eleven of those had received Prednisolone (ns). At the final follow-up total recovery had been reached for thirty-nine patients, nineteen of those had received Prednisolone (ns). These thirty-nine patients with total recovery at the final follow-up had a mean hearing loss of 60.5 dB ± 17.4. Thirteen of them had a hearing loss <50 dB HL, six treated with Prednisolone and seven placebo. The range of the hearing loss for the remaining twenty-six patients was 52–90 dB HL.

Table X. Prognostic factors at the first and final follow-up (day eight) on 93 patients in modified Intention-To Treat analysis.

First follow-up Final follow-up Predictor

Coef. SE Coef P-value

Coef. SE Coef P-value

Constant 46.80 21.47 39.22 25.76

Treatment -3.114 5.361 0.563* -0.827 5.807 0.887*

Age -0.256 0.189 0.180 -0.346 0.093

Heredity for hearing loss 10.287 6.013 0.091 8.700 6.397 0.178

Vertigo -15.706 5.749 0.008 -18.526 0.004

Tinnitus 4.233 5.788 0.467 -1.764 0.776

Time from onset of SSNHL to the first at the ENT clinics

0.350 1.218 0.775 1.509 1.326 0.259

Prescribed rest or sick leave 0.166 6.565 0.980 -3.367 7.414 0.651

Frequency regions 0.262 ! 0.524 !

Abnormal findings of radiological investigations -22.462 6.148 0.000 ns

Abnormal findings of laboratory work-ups 15.178 5.628 0.009

14.424 5.928 0.018

0.203

6.252

6.163

* A single-sided null-hypothesis, that there is less than 10 dB difference of treatment efficacy between the Prednisolon and placebo group was used.

! p-value refers to the partial F-test where null hypothesis is that there is no difference between regions.

Results 41

Predictive factors at the first and final follow-up (day eight and ninety) At the first follow-up, three factors were significantly related to outcome regardless of treatment:

The effect of vertigo was –15.7 dB (p=0.008) in the modified ITT analysis, –13.7 dB (p=0.032) in the PP analysis and –14.5 dB (p=0.041) in the total PP analysis.

Abnormal radiological findings had an effect of –22.5 dB (p=0.000) in the modified ITT analysis, –24.3 dB (p=0.001) in the PP analysis and –29.7 dB (p=0.001) in the total PP analysis.

The effect of abnormal laboratory findings was +15.2 dB (p=0.009) in the modified ITT analysis, +16.4 dB (p=0.008) in the PP analysis and +17.3 dB (p=0.031) in the total PP analysis.

At the final follow-up, modified ITT analysis and PP analysis showed slightly different prognostic factors for recovery than at the first follow-up, eight days after the treatment:

The effect of vertigo was –18.5 dB (p=0.004) in the modified ITT and –20.0 dB (p=0.003) in the PP analysis.

The baseline PTA for the affected frequencies had an effect of +0.4 dB (p=0.014) for in the modified ITT analysis and +0.4 dB (p=0.025) in the PP analysis. Thus after 90 days, the mean hearing gain was 40% of the initial hearing loss.

The effect abnormal findings of laboratory work-up was +14.4 dB (p=0.018) in the modified ITT analysis and +15.4 dB (p=0.016) in the PP analysis.

Total PP analysis of seventy-three patients who did take the study drug according to the protocol showed that the only factor affecting the outcome was presence of vertigo. The ability to recover dropped with 20.5 dB (p=0.007) for patients with vertigo.

42 Results

Paper IV The aim of Paper IV was to analyze a larger patient group by meta-analysis of data from the RCT together with corresponding material drawn from the Swedish national database for ISSNHL.

A total of one hundred ninety-two patients had been treated according to inclusion, eighty-seven from the RCT (III) and one hundred and five from the Swedish national database (II). At final follow-up audiogram was missing for five patients. Ninety-six of the total one hundred eighty-seven had received Prednisolone, forty-two placebo and forty-nine no treatment.

Baseline characteristics data for all groups are described in Table XI.

No significant difference in hearing recovery was observed regarding the effect of treatment between the total Prednisolone group and Placebo group plus the control group without treatment.

The estimated treatment efficacy was 6.10 dB (p=0.06), meaning that patients receiving Prednisolone recovered more than the placebo/no treatment group, but not significantly so.

The recovery with respect to frequency region that was affected by the hearing loss is presented in Table XII.

Analyzing all patients together, three variables were significantly related to outcome regardless of treatment: age at initial contact, presence of vertigo at the onset of hearing loss and abnormal findings of laboratory work-ups.

Age and presence of vertigo at the onset of ISSNHL was associated with less hearing improvement. The effect of age was –0.35 dB (p=0.003) which means that hearing improvement was less with increasing age of the patient (0.35 dB per year). The effect of vertigo was –15.2 dB (p<0.001).

“Abnormal laboratory findings” at the onset of the disease were associated with better prognosis for hearing improvement. “Abnormal laboratory findings” effect on hearing improvement was +11.0 dB (p=0.009). Most of these findings were signs of inflammation/infection.

Comparison between the placebo group and the control group (no medical treatment) No significant difference in hearing recovery was observed between the placebo group and control group without treatment. The estimated placebo efficacy was 5.90 dB (p=0.208), meaning that patients receiving placebo recovered not significantly more than those not medically treated.

Results 43

Discussion 45

DISCUSSION

Sudden sensorineural hearing loss is one of the most mysterious and controversial unsolved entities in otolaryngology. The lack of a standard definition for SSNHL, the low incidence and the fact that some spontaneous recovery occurs in up to 80% of cases, make any evaluation of treatment impossible for those ENT doctors who only see a few patients a year.

The criteria for SSNHL and for the assessment of hearing recovery were developed by the Sudden Deafness Research Committee of the Ministry of Health and Welfare in Japan (1973 and 1981, respectively). However, no specific instruction with regard to how sudden the onset of hearing loss should be, the degree of hearing loss or the affected frequencies were actually provided. Although many authors have selected a hearing loss of 30 dB HL in three contiguous frequencies for their studies1-5, the onset of hearing loss differs from 24 to 72 hours2,6,7. In the studies for this thesis (I–IV), hearing loss over a period of 24 hours was selected in order to stress the concept of “sudden” hearing loss and to avoid including patients with Mb Ménière or endolymphatic hydrops, where the hearing loss usually develops within a few days.

The seemingly low prevalence of ISSNHL in Sweden seen in the present thesis is far below 5–20 per 100.000 per year presented earlier13. However, in one ENT clinic in the countryside to which all patients in the region were referred, the prevalence was estimated to be 8 per 100.000 per year. In city regions, where many patients were treated in private practice, selection made it impossible to estimate prevalence/incidence. The number of patients to treat for ISSNHL seemed to decline over the study period, which could be observed at all fourteen contributing clinics (III). This may be due to decreasing interest for the study (III). No other reason is evident for a real decrease of incidence. In Japan, an epidemiological study for the last 30 years showed the opposite: an increasing prevalence of ISSNHL14.

One reason not to be included in the trial was doctor and patient bias. A prerequisite to perform a RCT is to be unbiased. Many of the ENT doctors treating at the contributing clinics had already formed opinions about the effect of corticosteroids and therefore had difficulties in answering patients’ common question: ”How would you treat it if you got this disease, Doc?” This made it difficult for them to recruit patients to the study. Patients today have often studied Internet even before the first visit and already formed a clear opinion about which treatment they wanted; a common reason for patients to refuse to participate was that they wanted corticosteroids.

Radiological and laboratory examination An acute hearing loss can be a symptom that can be caused by a multitude of known diseases within the vascular system or by different traumas and tumors within the hearing tracts38,42,43,62,63. In most cases of SSNHL, it will not be possible to arrive at a specific diagnosis. However, the assessments of these possible mechanisms should still

46 Discussion

be performed in order to find the approximately 10% of cases for which one can arrive at an identifiable, and hopefully treatable, diagnosis37.

Radiological examination Only around 40% of the patients had had an MRI or CT. The discovery of only 1.6% to 3.2% acoustic neuromas among these patients (I–III) was a low number when compared to other studies on sudden sensorineural hearing loss27,102,103.

In the RCT (III), only one patient with acoustic neuroma was discovered and that patient was treated with Prednisolone and improved. It might be expected that an acoustic neuroma would react to corticosteroids, thereby improving hearing when the tumor diminished or ceased pressing upon the blood vessels that feed the cochlea, as had been discussed in earlier works104.

Since hearing improvement was possible for almost all of the patients with tumors prior to their final diagnosis, a radiological examination of all patients with ISSNHL would be valuable in order to identify treatable acoustic neuromas.

Very often different vascular abnormalities or sign of ischemic vascular disease were found by MRI (I–III) irrespective of age. Most of these patients had a hearing loss in the low or mid frequency regions. The hearing loss could therefore theoretically be due to similar disease of blood vessels feeding the damage part of the cochlea. Unfortunately, these potential occlusions cannot at present be visualized radiologically. These patients might have benefited if given any specific treatment that was associated with their vascular abnormality.

The MRI examination in SSNHL is most often performed several weeks after the first visit to the ENT clinic, which makes it difficult for the physician to take the findings into consideration while deciding the acute treatment for the hearing loss. If the SSNHL of some patients were due to vascular accidents, the CT or MRI should be performed immediately in order for these tests to be of any value for the patients. This situation is quite similar to cases in which the best treatment of stroke and heart infarction occurs when patients are examined as soon as possible.

Laboratory examinations When a test battery is used in SSNHL as part of a blood laboratory examination, the results are not always easy to evaluate. Pathological tests may not necessarily be specific for the patient's hearing disorder. Even if the tests are specific, at least two tests within weeks of each other are often needed. For example, to see the rising titers of Borrelia antibodies in order to determine whether an infection is ongoing or has already past.

In study II, serological Borrelia analyses were most often done, with 11% yielding pathological findings. This is in accordance with earlier studies in which both serum and CSF analysis had been performed105. A third of the patients with increased Borrelia titers were primarily treated with antibiotics, but the effect on hearing outcome were not related to the treatment. This is in agreement with earlier studies with respect to ISSNHL106 and is similar to the use of antibiotics for the treatment of

Discussion 47

patients with facial palsy and high Borrelia titers. Since neuroborreliosis is a severe chronic disease that should be treated even if antibiotics do not specifically cure the hearing loss, high titers at the onset would at least justify a second test to be taken in order to verify or substantiate an ongoing infection so that treatment could be commenced or modified. However, very few additional tests had been taken in the present material.

Patients with pathological results of laboratory tests were categorized into “arteriosclerotic causes”, “inflammatory/infectious causes” or “autoimmune causes” to see whether one group or another had different outcomes or had received different treatment. The results from study II demonstrated that there was no difference in medical treatment policy among these different categories. The only alternatives were corticosteroids or nothing, and there was no difference in the outcomes between these two options. However, in study II in the atherosclerosis group, where a rheological treatment might theoretically have been appropriate, potential differences may be hidden by the fact that only a small fraction of the patients had their total cholesterol and LDL/HDL ratio evaluated. The association between increased CRP levels and atherosclerosis is obscured by other acute inflammatory reactions and also by the lack of standardized time intervals between the onset of SSNHL and the blood sampling. These circumstances may indicate that ordinary CRP is not the ideal marker for atherosclerosis in this setting. At least high sensitive CRP is needed in cases where no acute infection is ongoing.

The introduction of corticosteroids for Sudden Deafness during the 70’s was based on the hypothesis that it would relieve unknown infections/inflammations. However, neither proven presence of herpes virus or positive Borrelia findings concomitant with ISSNHL have shown to yield better outcome after treatment with corticosteroids83,106. It is interesting that patients in the RCT (III) with “inflammatory sign” had a better prognosis for hearing improvement, independently of Prednisolone or placebo treatment. This finding requires further research and can also be a reason for apparent effects of steroids in other non-RCT studies8,22,107.

Treatment The treatment of idiopathic sudden sensorineural hearing loss has always been based on one or another underlying hypothesis of the etiology. The vascular theory was the basis for anti-stress treatment, consisting of bed rest and blockage of ganglion stellatum, used primarily during the 1950’s20, and for treatment with dextran 40 and other hyperosmolar hemodilutive drugs during the 1970’s21. The inflammation/infection theory was the basis for the use of the anti-inflammatory properties of corticosteroids, which has been a treatment since the 1980’s2. More recently, the autoimmune theory108 became the basis for an increased dosage of steroids and additional cytostatic therapy109.

Only 57% of the patients with ISSNHL in study I and 61% of the patients with ISSNHL in Paper II had received any type of drug therapy with the aim of influencing the outcome. Eighty-nine percent (Paper I) and ninety-one percent (Paper II) of those who were medically treated received corticosteroids, even if the underlying etiology was unknown. The observed outcomes are in accordance with the conclusions from

48 Discussion

the Cochrane reports24,25, that the individuals who had received corticosteroids had the same odds for recovery as those who did not receive any drugs. The only randomized double-blinded placebo-controlled study where a positive effect of corticosteroids have been proposed, actually had too few patients to allow for drawing such a conclusion2.

Corticosteroids did not influence outcome in the few patients with positive autoimmune signs in the present thesis (II, III), although an effect on those might have been expected110. One explanation could be that too low dosage of corticosteroids for that purpose and no cytostatic drugs were given.

A recent study by Aoki et al., reported that a very high dosage of corticosteroids seems to give a significantly better recovery rate in patients with ISSNHL at completion of treatment, but not two months after treatment22. However, this study did not use a control group without medical treatment. In the present RCT (III) 42% recovered completely after three months equally in the Prednisolone and the placebo group.

Surprisingly enough, the 26% of patients who had been prescribed to rest had better odds for recovery (II). Earlier, bed rest and sick leave were standard treatment for ISSNHL patients, but this has become very uncommon nowadays. No research seems to have been performed with regard to that specific treatment modality. It is quite possible that all individuals who are afflicted by ISSNHL would experience some gain from rest—especially those individuals who in their questionnaire had reported recent stress before the onset of the disease.

Site of damage in relation to treatment Many authors are convinced that several different diseases can cause the symptom of hearing loss and might be included in the diagnosis ISSNHL. That can be a reason why no single treatment has given clear evidence of effect111. In Germany, an expert group has suggested that different shapes of the audiogram can tell about where in the cochlea the damage is and maybe explain the pathogenesis112: A low frequency loss might regarded as a sign of hydrops, a mid-frequency loss as a sign of vascular interference, a high frequency hearing loss of up to 40 dB HL should be a possible dysfunction of outer hair cells and a hearing loss of more than 40 dB HL as a dysfunction/damage also to the inner hair cells. A flat loss can be considered as an interference with the vascular stria giving an acute hearing loss due to a preceding acute ionic balance disturbance. It would be of utmost interest to see if different treatment policies will develop according to this hypothesis, as thus far only Corticosteroids and or rheological treatment are suggested112. This theoretical approach has as its weakness that it does not fit with experience from clinical praxis and the present study (III) that all types of audiograms seems to have a chance of spontaneous recovery and that recovery can either go as quickly as the hearing loss came or more slowly within a couple of months.

Prognostic factors Prognostic factors for ISSNHL have been studied by many authors. The findings which demonstrate that the presence of vertigo (II, III, IV) and a higher age (I, II, IV)

Discussion 49

at onset are related to a reduced probability for recovery, are also in accordance with earlier studies2,54,113,114. The fact that, a higher age is related to lower probability for recovery may be because older patients in general have more difficulty in recovering from illnesses. More widespread involvement of the disease in the inner ear could explain the reduced odds for recovery when ISSNHL is in combination with vertigo. The presence of tinnitus has been considered to be a positive prognostic factor for hearing recovery by Cvorović et al., 2008114, but, in the studies of this thesis (I–IV), no such connection was found. However, “heredity for hearing loss” or a close relative who was affected by hearing loss as a prognostic factor for SSNHL does not seem to have been previously discussed. In fact, the only study100 discussing positive family history of ISSNHL was published 2010. Gäckler et al., reported that 21.4% of ISSNHL patients had one or more family members affected by ISSNHL. ISSNHL patients with a positive family history were younger, had experienced more events of ISSNHL and had poorer hearing improvement under therapeutic treatment100. In the Papers (I, II) based on the Swedish national database, heredity was clearly related to a decreased probability of improvement. This might suggest that in some cases, the ISSNHL is the first sign of a hereditary, progressive hearing loss. However, in the present thesis the final follow-up was after only three months, thus it is not possible to evaluate a possible further progression.

Audiometry Comparing results from studies based on audiometric pattern is difficult since different classifications are used. One hypothesis about variation in recovery is that different types of hair cells are involved: If only the outer hair cells are damaged, a central adaptation might be possible so the remaining, undamaged outer hair cells can reorganize the cortical pattern and in that way restore hearing115. If however, the inner hair cells are involved, it is more difficult to visualize reorganization since their number in the cochlea is so limited and they are strictly tonotropically arranged both in the cochlea and all along the central pathways.

The weakness of this theoretical approach regarding the site of damage and the possibility of recovery is that it does not fit with the clinical observation that patients with all types of audiograms seem to have a chance to a spontaneous recovery of varying degrees—or that a hearing improvement can come about as quickly as the onset of the hearing loss. A more slowly developing recovery over a couple of months would better fit the theory regarding reorganization115.

The results that patients with an hearing loss in the mid frequency region had the best recovery rate (II) has been reported earlier in several studies2,6,54 and can be explained on the basis of a vascular theory for ISSNHL. In the cases when two arteries are supplying the cochlea, one would theoretically expect a hearing loss in the lower and mid frequency region with a chance of recovery through collaterals from the second main artery116. The presence of a second main artery occurs in about 50% of the cases117. The same reasoning can be adapted to the patients in the present thesis (II) with vascular aberrations who had none or moderate improvement. They may have had occlusion of the main auditory artery, but with no collateral supply from a second artery116.

50 Discussion

Suggestion for further research Whenever a drug or a substance is proven not to work for a specific condition, it should be withdrawn from use and the focus for research within the field turned in a new direction.

Further follow-ups of the patients included in the RCT are urgently needed to clarify different prognostic patterns.

ISSNHL is probably a symptom of several different disorders. If so, a comprehensive test battery would be developed to identify underlying diseases for a more adequate treatment. In such test battery, genetic examination should also be included if the case history reveals other relatives with same disease.

Further studies concerning chronic and acute stress are also indicated. This stress studies should include both qualitative research and laboratory examinations.

Conclusions 51

CONCLUSIONS

The following general conclusions can be drawn from the present thesis:

Regardless of diagnostic protocol, treatment of ISSNHL in Sweden is mainly limited to corticosteroids (50%) or to no medical treatment.

Presence of vertigo at the onset of SSNHL is negative prognostically for hearing recovery independently of treatment.

Higher age is negative prognostically for hearing recovery independent of treatment.

In a randomized placebo-controlled clinical trial no positive effect of Prednisolone on ISSNHL could be demonstrated.

A Meta-analysis of patient data from the Swedish national database for SSNHL and the RCT for ISSNHL demonstrated no effect of Prednisolone on ISSNHL.

Acknowledgments 53

ACKNOWLEDGMENTS

A number of people have contributed, inspired and helped me in preparing this thesis. I wish to express my sincere gratitude to all of you. I especially want to thank:

Professor emerita Elisabeth Hultcrantz, my main supervisor, for sharing her vast knowledge in “Sudden Deafness”, guidance in the scientific world, and above all for providing ideas, excellent teaching, enthusiasm and encouragement. Thank you for always having time to give advice and support wherever you have been at the moment.

Professor Torbjörn Ledin, my co-supervisor, for clarifying statistical terms for me and for valuable advice and support.

Professor emeritus Stig Arlinger, my co-supervisor, for sharing his endless knowledge in audiology, skillful editing and answering my questions so quickly.

Magnus Hansson, my co-author, at the department of Clinical Chemistry of Karolinska University Hospital, for valuable comments and help with clarification of laboratory tests.

Ed Paulette, for linguistic guidance and careful editing. For having the time and patirnce to discuss details.

Olle Eriksson and Karl Wahlin, at the department of Computer and Information Science, division of Statistics, for help with statistical counseling. In particular, I would like to express my gratitude to Olle for having patience and answering my “odd” questions. For his kindness to always make and have time for me.

Magnus Johansson, for help with system development of the database.

All staff at the ENT clinics and Audiological clinics in the hospitals of Bollnäs, Bäckefors, Enköping, Eskilstuna, Fagersta, Gällivare, Gävle, Helsingborg, Huddinge, Hudiksvall, Jönköping, Kalmar, Karlskrona, Karlstad, Katrineholm, Kristianstad, Köping, Lindesberg, Linköping, Lund, Lundby, Malmö, Mora, Mölndal, Norrköping, Sala, Skövde, Stockholm, Strömstad, Sundsvall, Södertälje, Trollhättan, Uddevalla, Umeå, Uppsala, Visby, Värnamo, Västerås, Ängelholm, Örebro, Örnsköldsvik and Östersund, for contributing to the Swedish national database and the RCT.

Susan Barclay Öhman, (The Barclay Consultancy AB) for professional assistance with structuring of the study.

Anette Lagergren, at the Audiological clinic of Linköping University Hospital, for support and good help in providing me time for my scientific work.

Gunilla Hydén, Torsten Pettersson, Joakim Blomgren and Lars Andersson, at the ENT clinic, the Audiological clinic of Linköping University Hospital and the division of Speech, Language Pathology of Linköping University, for always patiently answering my computer related questions.

My colleagues, at the Audiological clinic of Linköping University Hospital, Motala Hospital, the division of Technical Audiology and the division of Speech, Language Pathology of Linköping University, for providing a nice and friendly working environment and for the very entertaining coffee break discussions.

54 Acknowledgments

My friends Pia Granath, for letting me chill out in her office between the hard work and for patiently listening to me babbling about anything possible. I am grateful for your never-ending support and friendship. Linda Lindström and Elisabeth Ericsson, for all help and support. Dinners with you have been perfect breaks from work and have helped me to think of other things than “Sudden Deafness”.

My mother Pari, my late father Qasem and my brothers Ramin and Ramtin for love, support and for believing in me.

Finally, I have many reasons to be grateful to my beloved husband Reza and our wonderful children Alma and Arvid.

Reza, for your love, support and patience. You are everything I have ever wished for with your kindness, concern and selflessness. Alma and Arvid, for being who you are and bringing me down to the earth again when I feel lost in the mist.

Financial support has gratefully been received from Medical Research Council of Southeast Sweden (FORSS), the Country Council of South East Sweden, Linköping University, StingerFonden, Stiftelsen Tysta Skolan and Gunnar Arnbrinks Stifte

Svensk sammanfattning 55

SVENSK SAMMANFATTNING

Idiopatisk Plötslig Sensorineural Hörselnedsättning Diagnostiskt protokoll och kortikosteroidbehandling i relation till resultat

Bakgrund Idiopatisk Plötslig Sensorineural Hörselnedsättning (IPSH) är en av de gåtfulla sjukdomar vilka drabbar innerörat och nerverna som passerar den inre hörselkanalen. Oavsett behandling återkommer hörseln fullständigt hos ungefär en tredjedel av patienterna och delvis hos en tredjedel, medan resten får kvarstående betydande hörselnedsättning ofta i kombination med tinnitus eller obehag av ökad ljudkänslighet. Sjukdomen har tidigare beräknats drabba 5 – 20 per 100 000 invånare årligen men incidensen är osäker, då det är svårt att veta hur många som insjuknat pga. högt spontant tillfrisknande innan något läkarbesök har skett.

Orsaken till sjukdomen är okänd. Detta har lett till att patienter både i Sverige och globalt genom åren har fått olika behandlingar beroende på vilken hypotes om sjukdomens orsak läkarna har stött sig på:

Infektionsteorin: Redan 1907 rapporterade Hunt att Herpes zoster kan orsaka plötslig hörselnedsättning. Andra bakteriella sjukdomar såsom Borrelia och syfilis, och virala som påssjuka och röda hund är också kända orsaker till plötslig hörselnedsättning. Om man antar att alla fall av IPSH har denna genes använder man sig av antibiotika eller antivirala läkemedel, (acyklovir och valacyclovir). De fyra hitintills publicerade randomiserade, placebo-kontrollerade kliniska studier med acyklovir och valacyclovir visar emellertid inte någon signifikant effekt av den behandlingen.

Immunologisk teori: McCabe (1979) var först med att föreslå autoimmunitet som orsak till plötslig hörselnedsättning. Han baserade sin hypotes på kliniska data, patologiska fynd vid autoimmunologiska tester och förbättrad hörsel av kortikosteroid terapi. Hörselnedsättningen kan vara en följd av lokala autoimmuna processer som bryter ned enbart vävnaden i innerörat eller en systemisk autoimmun sjukdom som t.ex. Cogans syndrom, Wegeners sjukdom och systemisk lupus erythematosus (SLE). Behandling av IPSH med kortikosteroider är baserat på denna immunologiska teori.

Sedan man började behandla IPSH med kortikosteroider på 1980-talet har det gjorts många studier om deras effekt, men de enda två som varit randomiserade dubbelblinda placebokontrollerade från 1980 och 2001 har visat motsägande resultat och haft låg ”power”.

Fistelteorin: Rupturer antingen inom snäckan med jonrubbningar som följd och orsak till hörselnedsättning, eller av membranen i runda eller ovala fönstret med ett resulterande perilymfaläckage som symptomorsak är en teori om IPSH. Rupturen anses inte ske spontant utan uppträder efter plötslig tryckändring i mellanörat i samband med huvudskador, barotrauma eller intensiv fysisk aktivitet. Kirurgi med tätning av misstänkta hål i runda fönstermembranet i kombination med ordination av strikt sängläge är en behandlingsmetod, men inte heller här är man ense om nyttan av denna terapi.

56 Svensk sammanfattning

Blodkärlteorin: Ett minskat blodflöde i den ändartär som försörjer örat skulle kunna orsaka plötslig hörselnedsättning. Sjukdomar i blodkärl eller hematologiska åkommor förknippade med plötslig hörselnedsättning har också rapporterats såsom vid Buergers sjukdom, leukemi och sickelcellsanemi. Vid IPSH har olika behandlingar såsom extrakorporeal defibrinogering, Rheomacrodex® och andra hyperosmolara blodförtunningsmedel använts baserat på denna teori. Det finns vetenskapligt stöd både för och mot sådan terapi.

På grund av den låga incidensen, det spontana tillfrisknandet i vissa fall och möjligheter av mer än en orsak till sjukdomen är effekten av behandling av IPSH alltid svår att bedöma på en enskild klinik där man endast ser ett mindre antal patienter per år. Genom att samla data från ett stort antal patienter finns möjlighet att identifiera prognostiska faktorer och olika behandlingar för IPSH i Sverige. Den vanligaste behandlingen för IPSH kan sedan att jämföras med placebo för att utvärdera av effekten av behandlingen gällande hörselförbättring.

Syfte Syftet med denna avhandling var att kartlägga vilken utredning och behandling patienter med IPSH får i Sverige och sedan utvärdera effekten av den vanligaste behandlingen vad gäller hörseltillfrisknande i jämförelse med placeboterapi.

Studie I Att kartlägga behandlingspolicyn för IPSH i Sverige.

Att utvärdera behandlingseffekten av terapi med avseende på hörseltillfrisknande.

Att kartlägga vilka variabler såsom ålder, tinnitus, yrsel, tidigare sjukdomar och hörselkurvornas utseende har prognostisk värde vid insjuknandet i IPSH.

Studie II Att undersöka vilka olika diagnostiska testbatterier för IPSH som för

närvarande används i Sverige.

Att utvärdera om patologiska diagnostiska fynd leder till behandlingsmodifikationer och i så fall hur.

Att undersöka om behandlingsmodifikationer påverkar tillfrisknandet.

Studie III Att utvärdera effekten av kortikosteroider (Prednisolon) i hög nedtrappningsdos

vid behandling av IPSH i jämförelse med placebo.

Studie IV Att med metaanalys utvärdera effekten av kortikosteroider (Prednisolon) i

nedtrappningsdos vid behandling av IPSH i jämförelse med placebo eller ingen

Svensk sammanfattning 57

behandling alls. Med ett större antal patienter får man högre säkerhet av sina resultat.

Metod De två första publikationerna (I, II) i denna avhandling är baserade på data från en nationell databas i Sverige för plötslig sensorineural hörselnedsättning.

Den nationella databasen om plötslig sensorineural hörselnedsättning startades sent 2002 i Linköping.

Ett frågeformulär hade tagits fram som fylldes i av den först konsulterade öronläkaren, när patienten sökte för sin hörselnedsättninh. Frågorna berörde patientens tidigare sjukdomar, trauma, tinnitus, yrsel, ärftlighet för olika sjukdomar särskilt hörselnedsättning samt viken utredning och behandling som planerades/gavs av den aktuella plötsliga hörselnedsättningen. Två audiogram, ett taget vid insjuknandet och ett vid kontroll efter tre månader skickades tillsammans med frågeformuläret till databasen. Se appendix.

För bedömning av hörselnedsättningen jämfördes det initiala audiogrammet med ett audiogram taget innan den akuta hörselnedsättningen. För att kategorisera nedsättningarna definierades fyra frekvensområden: basområdet: skillnad i hörtröskelmedelvärde vid 125-250-500 Hz, mellanregistret vid 1000-1500-2000 Hz, diskantområdet vid 3000-4000-6000 Hz och ”flat loss” om skillnaderna i försämring mellan de tre frekvensbanden var mindre än 10 dB HL.

I studie II kategoriserades patologiska laboratoriefynd (blodprov) på följande sätt: “Arteriosklerosassocierade variabler”: LDL-kolesterol/HDL-kolesterol >3,

Totalkolesterol >5 mmol/L och C-reaktivt protein (CRP) >3 mg/L hos patienter med eller utan tidigare hjärt-kärl sjukdomar.

“Inflammation/infektionassocierade variabler”: CRP >10 mg/L, ”Sänka” >20 mm, Vita blodkroppar >10 x 109ml/L, Hemoglobinhalt <120 g/L, Trombocytantal >150 x 109ml/L och Borrelia test “positiv” (IgG antikroppar och IgM antikroppar) hos patienter med eller utan kliniska tecken på infektion.

“Autoimmuna variabler”: förekomst av patologiska värden av HSP-70, Kardiolipin, Antifosfolipid, Antineutrofila cytoplasmiska antikroppar (ANCA) och Antinukleära antikroppar (ANA) “positiv”.

Studie III En randomiserad trippel-blind, placebo-kontrollerad multicenterstudie om effekten av kortikosteroid på IPSH genomfördes mellan januari 2006 och september 2010. Fjorton ÖNH kliniker i Sverige deltog i studien.

Patienter mellan 18 – 80 år med plötslig påkommande sensorineural hörselnedsättning inom 24 timmar och utan någon känd etiologi tillfrågades om att ingå i studien. Hörselnedsättningen skulle vara minst 30 dB HL eller mer i tre närliggande frekvenser och patienterna skulle ha kommit till ÖNH klinikerna inom 7 dagar från insjuknandet. Exklusionskriterier var graviditeten, diabetes, kroniska infektioner, magsår,

58 Svensk sammanfattning

okompenserad hjärtsjukdom, nylig operation, eller psykisk sjukdom. Ett registreringsformulär (CRF) samlades in för varje patient. CRF bestod av en enkät, audiogram, information om radiologiska undersökningar (MRT eller CT), laboratorietester, hjärnstamsaudiometri (BRA), enligt de olika klinikernas praxis, och information om biverkningar. Frågeformuläret var en modifierad version av frågeformuläret som användes för den svenska databasen för IPSH. Alla patienter fick skriftlig information om sjukdomen plötslig sensorineural hörselnedsättning och om syftet med studien samt ett nedtrappningsschema för medicinen. En engångsdos på 60 mg Prednisolon eller placebo gavs dagligen i tre dagar, sedan minskats dosen med 10 mg per dag, med en total behandlingsperiod på åtta dagar. Om total hörselåterhämtningen hade skett, avslutade man behandlingen då, annars fortsatte medicinering med 10mg dagligen till sammanlagt 30 dagar från början. Uppföljningsbesök var planerad för dag åtta ± en dag, 1 månad och 3 månader efter randomisering. Om återhämtning var fullständig på dag åtta, skedde nästa uppföljning vid 3 månader.

Studie IV För att höja tillförlitligheten av de resultat som framkommit i studie III, ökades patientmaterialet med motsvarande data från den svenska databasen för PSH. Patienter från den svenska nationella databasen som hade fått samma eller likvärdig behandling som patienterna i RCT valdes. Behandlingen hade varit engångsdos på 60 mg Prednisolon dagligen i tre dagar, sedan minskats dosen med 10 mg/dag, med en total behandlingstid på minst åtta dagar. Kontrollgruppen från RCT var placebobehandlade patienter, med audiogram vid start och efter 3 månader. Kontrollgruppen från den svenska nationella databasen var de som inte hade fått Prednisolon eller annan specifik behandling, men undersökts med audiogram vid det första besöket och efter 3 månader.

Material

Studie I Trehundra patienter med plötslig hörselnedsättning som initialt hade diagnostiserats som ”Plötslig dövhet/plötslig sensorineural hörselnedsättning” av sina lokala öronläkare och som inkluderats i den svenska nationella databasen. Av dessa trehundra patienter hade nittiotvå antingen ledningshinder, Mb Ménière, eller andra kända inneröre- eller mellanöresjukdomar, eller mindre än 30 dB HL hörselförlust, färre än tre närliggande frekvenser drabbade eller hade insjuknat under mer är 24 timmar. Se tabell II.

Studie II Fyrahundra patienter (300 från studie I samt ytterligare 100) vilka initialt hade diagnostiserats som ”Plötslig dövhet/plötslig sensorineural hörselnedsättning” och därför rapporterats till databasen.

Svensk sammanfattning 59

Studie III

Etthundratre patienter med IPSH randomiserades jämnt till behandling med antingen Prednisolon eller placebo. Tio patienter uteslöts från analyserna, fyra av dem i behandlingsgruppen och sex i placebogruppen. Se fig. III.

Nittiotre patienter analyserades som modifierad intention-to treat, fyrtiosju fick Prednisolon och fyrtiosex placebo.

Åttiosju patienter (av nittiotre patienter) som tog studieläkemedlet enligt protokollet under de första åtta dagarna av behandlingsperioden analyserades som” Per Protokoll”, 45 tillhörde behandlingsgruppen och 42 placebo. Fjorton av dessa åttiosju patienter skulle antingen ha fortsatt att ta studieläkemedlet upp till 30 dagar eller inte men inte enligt protokollet. Sjuttiotre patienter (av nittiotvå tre patienter) som tog studieläkemedlet i enlighet med protokollet analyserades som ”Totalt per protokoll” (totalt PP), trettioåtta tillhörde behandlingsgruppen och trettiofem placebo.

Studie IV

Totalt 192 patienter ingick i studien, 87 från RCT om IPSH och 105 från den svenska nationella databasen för PSH. Nittionio av de totala 192 hade fått Prednisolon, 42 placebo och femtio ingen behandling alls.

Varje patients hörsel utvärderades dels vid det första besöket på ÖNH-kliniken och dels efter tre månader. Vid den slutliga uppföljningen, saknades audiogram för två patienter i Prednisolon gruppen (RCT), för en patient i kortikosteroidgruppen (den svenska databasen) och för två patienter i kontrollgruppen (den svenska nationella databasen).

Resultat

Studie I Ingen av patienterna i den svenska nationella databasen hade bilateralt PSH. Av 300 patienter som rapporterades till databasen, hade 208 patienter bedömts enligt de definierade kriterierna att ha IPSH.

Alla 208 patienterna hade genomgått en ÖNH undersökning, 68% hade tagit blodprover och 37% hade undersökts med MRT. Tiden från debut av IPSH till första besöket på ÖNH-kliniken varierade med ett medianvärde på 5 (Range 0-212).

Oavsett medicinsk behandling eller ingen behandling alls hade ålder och ”ärftlighet för hörselnedsättning” signifikant samband med lägre odds för hörselförbättring.

Hörselförlust i mellanregistret hade signifikant bättre möjligheter till hörselförbättring jämfört med basregister-, och diskantförluster.

Etthundrafem patienter (50%) av de totala 208 patienter hade behandlats med kortikosteroider och 90 (44%) hade inte fått någon medicinsk behandling. Tre

60 Svensk sammanfattning

patienter av de återstående elva patienterna fick antiviral terapi och fem fick antibiotika.

Det fanns ingen signifikant skillnad i hörseltillfrisknande mellan patienter som hade behandlats med kortikosteroider och de som inte hade behandlats medicinskt.

Studie II Av fyrahundra patienter som hade rapporterats till databasen, bedömdes trehundra patienter lida av IPSH.

Ett hundrafemtioåtta (40%) av de fyra hundra patienterna med PSH hade undersökts med MRT/ CT, tjugutvå hade patologiska fynd. Tio patienter av de tjugotvå patienterna med patologiska fynd, hade fynd som inte var kopplat till hörseln och kunde därför definierades som IPSH. Inget signifikant samband påvisades mellan patologiska MRT-fynd med vare sig hörselförbättring eller kvarvarande hörselnedsättning för patienter med IPSH.

Hematologiska test togs i tvåhundra åtta (65%) fall av totalt fyra hundra. Av de tre hundra patienter som ansågs ha IPSH, hade hundra nittiosex en eller flera tester tagna, och fyrtiosju (24%) av dessa hade en eller flera patologiska fynd. Det fanns inget samband mellan någon av laboratorietester med vare sig hörselförbättring eller kvarvarande hörselnedsättning.

Ett hundraåttiotvå patienter (61%) av 300 med IPSH hade behandlats medicinsk. Av dessa hade 166 fått kortikosteroider antingen som enda behandling eller i kombination med antiviral behandling, antibiotika eller blodförtunnande behandling (acetylsalicylsyra). Den medicinska behandlingen hade ingen signifikant korrelation med vare sig hörselförbättring eller kvarvarande hörselnedsättning.

Patienter som hade ordinerats vila eller varit sjukskrivna under den första perioden av sjukdomen hade högre odds för hörselförbättring, oberoende av någon annan behandling.

Hörselförlust i mellanregistret hade signifikant bättre chans till hörselförbättring jämfört med basregister och diskant.

Tre faktorer var signifikant relaterade till hörselförbättring oavsett medicinsk behandling eller ingen behandling, nämligen ålder och ”ärftlighet för hörselnedsättning" samt förekomst av yrsel vid insjuknandet.

Studie III Nittiotre patienter analyserades med modifierad ITT, fyrtiosju fick Prednisolon och fyrtiosex placebo.

Ingen signifikant skillnad av hörselförbättring observerades varken på dag åtta eller dag 90 mellan Prednisolongruppen och placebogruppen gällande effekten av behandlingen. Den beräknade behandlingseffekten vid första uppföljningen var -3,1 dB (p=0,563) och -0,83 dB (p=0,887) vid dag 90 för de nittiotre patienter i modifierade ITT-analysen. D.v.s. terapin hade inte medfört någon förbättring.

Svensk sammanfattning 61

Vid PP-analys uppskattades behandlingseffekten vid första uppföljningen till -2,48 dB (p=0,662)och för den totala PP analysen -2,91 dB (p=0,675), d.v.s. hörseln i Prednisolongruppen förbättrades mindre än placebogruppen. Den beräknade behandlingseffekten på den slutliga uppföljningen för PP-analysen var -0,18 dB (p=0,976) och för den totala PP-analysen -0,06 dB (p=0,994). Total hörselförbättring hade uppnåtts för tjugo patienter efter åtta dagar av medicinering, elva av dem hade fått Prednisolon (ns). Vid den slutliga uppföljningen hade total återhämtning uppnåtts för trettionio patienter, nitton av dem hade fått Prednisolon (ns).

De faktorer som hade samband med hörselförbättring oavsett medicinsk behandling eller ingen behandling var yrsel vid insjuknandet, onormala fynd av MRT och onormala fynd av lab-prover.

Studie IV Totalt 192 patienter hade behandlats enligt inklusionskriterierna, åttiosju från den randomiserade kliniska studien (III) och etthundrafem från den svenska nationella databasen (II). Vid den slutliga uppföljningen saknades audiogram för fem patienter. Nittiosex patienter av de totalt hundraåttiosju hade fått Prednisolon, fyrtiotvå placebo och fyrtionio ingen behandling.

Ingen signifikant skillnad i hörselförbättring kunde påvisas med avseende på behandlingseffekten mellan Prednisolongruppen och placebogruppen plus kontrollgruppen utan behandling. Den uppskattade behandlingseffekten var 6,10 dB, vilket innebär att patienter som fått Prednisolon återhämtade sig mer än de som fått placebo/ingen behandling, men skillnaden var inte signifikant. Vid analys av alla 187 patienterna var oavsett behandling tre variabler signifikant relaterade till hörselförbättring: ålder, förekomst av yrsel vid insjuknandet av PSH och onormala fynd av lab-prover. Ålder och yrsel hade en negativ inverkan på tillfrisknandet medan onormala lab-prover av inflammationstyp visade sig ha en positiv effekt på slutresultatet.

Diskussion Plötslig sensorineural hörselnedsättning är en av de gåtfulla sjukdomarna som drabbar innerörat och nerverna som passerar den inre hörselkanalen.

Den låga incidensen av PSH, bristen på en standard definition för PSH, och det faktum att spontan återhämtning mer eller mindre kan ske i upp till 80 %, har lett till att behandlingseffekten varit svårt att bedöma på en enskild klinik, där man endast ser ett mindre antal patienter per år.

Kriterier för PSH och för bedömningen av hörseltillfrisknande utvecklades av ”the Sudden Deafness Research Committee of the Ministry of Health and Welfare” i Japan (1973 resp. 1981). Men graden av hörselnedsättning, berörda frekvenser eller hur plötslig hörselförlusten bör vara har inte tagits upp. Många författare har valt en hörselförlust på 30 dB i tre närliggande frekvenser för deras studier men hur plötslig uppkomsten av hörselförlusten har varit är olika (24-72 timmar). I denna avhandling

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(I - IV) har hörselförlust under 24 timmar valts för att betona begreppet "plötslig" hörselnedsättning och för att undvika att inkludera patienter med Mb Ménière eller hydrops, där hörselnedsättning utvecklas vanligen inom några dagar.

Den låga prevalensen av PSH i Sverige som setts i denna avhandling är långt under den tidigare presenterade 5-20 per 100 000 per år. Men för en deltagande ÖNH-klinik i landet som alla patienter i regionen hade remitterats till, kan prevalensen uppskattas till 8 per 100 000 per år. Att uppskatta prevalens/incidens i storstadsregionerna där många patienter behandlats hos privatpraktiker är omöjligt. Antalet patienter att behandla för IPSH verkade minska under studieperioden, vilket kunde observeras vid alla fjorton bidragande kliniker (III). Detta kan bero på minskande intresse för studien (III). Ingen annan orsak är uppenbart för en verklig minskning av incidensen. En epidemiologisk studie för de senaste 30-åren i Japan visade istället en ökad prevalens av IPSH.

Ett skäl för att inte bli inkluderad i studien var läkare- och patient ”bias”. En förutsättning för att utföra en randomiserad klinisk prövning är att vara objektiv. Många av de ÖNH-läkarna på de bidragande kliniker hade redan åsikter om effekten av kortikosteroider på PSH och därför hade svårt att svara patienternas vanliga fråga: "Hur skulle du behandla dig om du själv fick den här sjukdomen?" Det gjorde det svårt för läkarna att rekrytera patienter till studien. Idag har patienter ofta studerat Internet innan det första besöket och har redan en klar uppfattning om vilken behandling de vill ha. En vanlig orsak till att patienter inte ville delta i studien var att de ville ha kortikosteroidbehandling.

Radiologiska och laboratorieundersökning En akut hörselförlust kan vara ett symptom som kan orsakas av en mängd kända sjukdomar inom blodkärlsystemet eller av olika trauman och tumörer. I de flesta fall av PSH, kommer det inte att vara möjligt att komma fram till en specifik diagnos.

Radiologisk undersökning Endast 40 % av patienterna hade undersökt med MRT eller CT. Upptäckten av endast 1,6 % - 3,2 % akustikusneurinom bland dessa patienter (I - III) var en låg siffra jämfört med andra studier om plötslig sensorineural hörselnedsättning. I den randomiserade kliniska prövningen (III), hade enbart en patient akustikusneurinom och patienten behandlades med Prednisolon och fick sin hörsel tillbaka fullständigt. Ett akustikusneurinom kan förväntas reagera på kortikosteroider och när tumören minskat eller upphört att trycka på blodkärlen som ger näring till snäckan, kan hörseln förbättras. En radiologisk undersökning (MRT/CT) av alla patienter med IPSH skulle vara värdefullt för att identifiera behandlingsbara akustikusneurinom. Alla patienter med akustikusneurinom i denna avhandling (I-III) hade hunnit få en hörselförbättring innan MRT/CT undersökningen, som hade gjorts flera veckor efter insjuknandet. Genom MRT (I-III) upptäcktes ofta olika blodkärlförändringar som möjligen kunde kopplas till IPSH. De flesta av dessa patienter hade en hörselförlust i basen eller mellanregistret. Den typen av hörselförlust kan teoretiskt bero på sjukdom i det blodkärl som försörjer det skadade delen av cochlean. Denna potentiella ocklusion kan

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för närvarande inte visualiseras radiologiskt. Dessa patienter kunde ha haft nytta av en specifik behandling avsett för blodkärlförändringar. MRT/CT undersökningar av PSH patienter görs ofta flera veckor efter insjuknande vilket gör det svårt för läkaren att ta hänsyn till resultaten vid beslut om akut behandling. Om PSH vid vissa fall beror på blodkärlförändringar, borde MRT/CT utföras omedelbart för att dessa undersökningar skulle kunna vara av något värde för patienterna. Denna situation är ganska lik de fall där den bästa behandlingen för stroke och hjärtinfarkt kan sättas in när patienterna undersöks så snart som möjligt.

Laboratorieundersökningar Hematologiska prover som tas i PSH fall är inte alltid lätta att utvärdera. Patologiska undersökningar behöver inte nödvändigtvis vara specifika för patientens hörselsjukdom. Även om proven är specifika behövs det oftast minst två prover inom några veckor från varandra. Till exempel, för att se stigande titrar av Borrelia antikroppar för att avgöra om det är en pågående eller tidigare infektion.

I studie II var serologiska Borreliaanalyser oftast gjort, med 11% patologiska fynd. Detta är i enlighet med tidigare studier där både serum och CSF analys hade utförts. En tredjedel av patienterna med ökade Borrelia titrar behandlades främst med antibiotika, men effekten på hörseln var inte relaterat till behandlingen. Detta stämmer väl överens med tidigare studier gällande IPSH och liknar även användningen av antibiotika för behandling av patienter med facialispares och höga Borrelia titrar. Eftersom neuroborreliosis är en svår kronisk sjukdom som bör behandlas. Även om antibiotika inte specifikt botar hörselskador, skulle höga titrar motivera ett andra test för att bekräfta en pågående infektion så att behandling kunde sättas in. I det aktuella materialet hade dock mycket få andra test tagits.

Patienterna med patologiska fynd av laboratorietester hade kategoriserats i "arteriosklerosassocierade variabler", " inflammation/infektionassocierade variabler " eller "autoimmuna variabler" för att se huruvida dessa grupper hade fått olika behandlingar och om detta påverkat resultatet. Resultaten visade ingen skillnad av den medicinska behandlingen mellan dessa olika kategorier. Det enda alternativet var kortikosteroider eller ingenting och det förelåg ingen skillnad i tillfrisknande dem emellan.

Införandet av kortikosteroider för PSH under 70-talet byggde på hypotesen att det skulle lindra okända infektioner/inflammationer. Men varken förekomst av herpesvirus eller positiva fynd av Borrelia i kombination med IPSH har visat sig ge bättre resultat efter behandling med kortikosteroider. Det intressanta är att patienter med " inflammation/infektionassocierade variabler " i den randomiserade kliniska prövningen (III) hade en bättre prognos för hörseltillfriskanande, oberoende av Prednisolon eller placebo. Detta fynd kräver ytterligare forskning och kan också vara en orsak till synbara effekter av steroider i andra icke-randomiserade studier.

Behandling Behandling av idiopatisk plötslig sensorineural hörselnedsättning har alltid varit baserat på en eller annan underliggande hypotes om orsaken. Blodkärlteorin ligger till

64 Svensk sammanfattning

grund för anti-stress behandling, bestående av sängliggande och blockering av ganglion Stellatum, som användes främst under 1950-talet, och för behandling med dextran 40 och hemodilution under 1970-talet. Inflammation/infektionsteori var grunden för användningen av antiviral terapi tillsammans med kortikosteroider en 1980-talet. Mer nyligen blev den autoimmuna teorin grunden för en ökad dos av steroider och cytostatisk behandling.

Endast 57 % av patienterna med IPSH i studie I och 61 % av patienterna i studie II hade fått någon typ av medicinsk behandling. Åttionio procent (studie I) och nittioen procent (studie II) av dem som var medicinskt behandlade hade fått kortikosteroider, även om den underliggande orsaken inte var okänd. Att de som fick kortikosteroider hade samma odds för tillfrisknande som de som inte fick något alls är helt i enlighet med slutsatserna från de senaste Cochrane rapporterna om IPSH från 2006 och 2009. Den enda randomiserade dubbelblind placebokontrollerade studien, där en positiv effekt av kortikosteroider har påvisats, hade för få patienter för en sådan slutsats.

Kortikosteroider påverkade inte resultatet för de fåtal patienter med autoimmuna fynd i denna avhandling (II, III), även om en effekt kunde ha förväntats. En förklaring kan vara att alltför låg dos av kortikosteroider använts för detta ändamål och ingen cytostatika givits.

Aoki med flera rapporterade nyligen (2006) att en mycket hög dos av kortikosteroider verkar ge en betydligt större odds för hörselförbättring efter två månader. Men denna studie har inte använt någon kontrollgrupp som inte har behandlats medicinskt. I den randomiserade kliniska prövningen (III) hade 42 % av patienterna fått sin hörsel tillbaka efter tre månader, jämt antal i både Prednisolon- och placebogruppen.

26 % av patienterna som hade ordinerats att vila hade bättre odds för hörseltillfrisknande (II). Tidigare var sängliggande och sjukledighet standardbehandling för patienter med IPSH, men detta har numera blivit mycket ovanligt. Ingen forskning har gjorts kring denna speciella behandlingsmetod. Det är mycket möjligt att alla individer som drabbas av IPSH skulle uppleva någon förbättring av vila, särskilt de personer som hade rapporterat stress innan sjukdomsdebuten.

Skada i olika delar av innerörat i relation till behandling Många forskare är övertygade om att flera olika sjukdomar kan orsaka hörselnedsättning och kan ingå i diagnosen IPSH. Det kan vara en anledning till varför ingen enskild behandling har påvisat en klar effekt på PSH. I Tyskland har en expertgrupp föreslagit att olika typer av hörselnedsättning kan ge en förklaring till var i hörselsnäckan skadan kan ligga: hörselförlust i basregistret kan ses som ett tecken på hydrops och hörselförlust i mellanregistret kan ses som ett tecken på cirkulationsstörning i en viss del av snäckan. Hörselnedsättning upp till 40 dB HL i diskanten kan vara skadade yttre hårceller och en hörselnedsättning på mer än 40 dB HL kan ses som en skada på de inre hårcellerna. ”Flat loss” kan anses som en påverkan av stria vaskularis vilket kan ge en akut hörselnedsättning på grund av akut jonbalansstörning. Det skulle vara av stort intresse att se om olika behandlingar utvecklas av denna hypotes. Detta teoretiska synsätt har sina svagheter då den inte

Svensk sammanfattning 65

överstämmer med klinisk erfarenhet och resultat från den randomiserade kliniska prövningen (III) som visar att alla typer av hörselnedsättning tycks ha en chans att spontant tillfrisknande. Återhämtningen kan antingen gå lika snabbt som när hörselnedsättningen kom eller långsammare inom ett par månader.

Prognostiska faktorer Prognostiska faktorer för IPSH har studerats av många forskare. Att förekomsten av yrsel (II, III, IV) och ålder (I, II, IV) vid insjuknandet är relaterade till minskat odds för hörselförbättring är i enlighet med tidigare studier. Att ålder är relaterad till minskad sannolikhet för hörselförbättring kan bero på att äldre patienter har i allmänhet svårare att återhämta sig från sjukdomar. Mer utbrett engagemang av sjukdomen i innerörat kan förklara det minskade oddsen för återhämtning när yrsel förekommer vid IPSH. Förekomsten av tinnitus har ansetts vara en positiv prognostisk faktor för hörselförbättring av Cvorovic med flera, men resultat från denna avhandling (I - IV) kunde inte påvisa ett sådant samband. Men "ärftlighet för hörselnedsättning" som en prognostisk faktor för PSH har inte tidigare diskuterats. Den enda studie som tar upp ”ärftlighet för hörselnedsättning” vid IPSH publicerades 2010. Gäckler med flera rapporterade att 21,4 % av patienter med IPSH hade en eller flera familjemedlemmar som tidigare drabbats av IPSH. Patienter med IPSH med ” ärftlighet för hörselnedsättning” var yngre, hade upplevt fler episoder av PSH och hade lägre hörselförbättring vid behandling. I studierna (I, II), baserat på den svenska nationella databasen, var ärftlighet tydligt relaterade till en minskad sannolikhet för förbättring. Detta kan tyda på att IPSH i vissa fall är det första tecknet på en ärftlig, progressiv hörselnedsättning. Den sista uppföljningen i denna avhandling var efter tre månader varför en fortsatt förbättring/försämring är inte möjlig att utvärdera.

Audiometri En hypotes om variation i hörseltillfrisknandet är att olika typer av hårceller är inblandade. Om bara de yttre hårcellerna är skadade, kan en central anpassning vara möjligt så de återstående oskadade yttre hårcellerna kan omorganisera och på det sättet återställa hörseln. Om däremot de inre hårcellerna är inblandade, är det svårare att visualisera omorganisation eftersom antalet inre hårceller i snäckan är begränsat och att de är tonotopiskt organiserade. Svagheten i detta teoretiska förhållningssätt gällande hörselskadans läge och möjligheten till hörselförbättring är att det inte passar ihop med den kliniska observationen att alla typer av hörselnedsättning verkar ha en chans till spontan återhämtning av varierande grad. Samt att hörselförbättringen kan ske så snabbt som uppkomsten av hörselförlusten. En långsammare utveckling av återhämtning under ett par månader skulle bättre passa teorin om omorganisation.

Patienter med hörselförlust i mellanregistret hade signifikant bättre chans till tillfrisknande (II). Detta har kunnat visas i en del tidigare studier och kan förklaras utifrån blodkärlsteorin. I de fall där det finns två artärer till cochlean, vilket förekommer i cirka 50% av fallen, och det ena blir blockerat, kan man teoretiskt räkna med en hörselnedsättning i de lägre och mellersta frekvenserna med chans till tillfrisknande eftersom det då finns anastomoser. Samma resonemang kan gälla för de patienter i denna avhandling (II) som hade ingen eller måttlig förbättring :de kan ha

66 Svensk sammanfattning

haft blodkärlförändringar, men ingen andra artär som kunde ge kollateralblodflöde.

Förslag på vidare forskning När ett läkemedel eller en substans visat sig inte ha effekt på en sjukdom, bör det tas ur bruk och fokus för forskningen inom området bör vändas i en ny riktning.

Ytterligare uppföljning av de patienter som ingår i den randomiserade kliniska prövningen behövs för att tydliggöra olika prognostiska mönster.

IPSH är förmodligen ett symptom för flera sjukdomar. Om så är fallet skulle ett omfattande testbatteri tas fram för att identifiera underliggande sjukdomar för en mer adekvat behandling. I ett sådant testbatteri bör också genetisk undersökning ingå om släktingar med samma sjukdom upptäcks i sjukhistorien.

Fler studier om kronisk och akut stress är nödvändiga. Dessa studier kring stress bör omfatta både kvalitativ forskning och laboratorieundersökningar.

Konklusioner Följande generella slutsatser kan dras från denna avhandling:

Oavsett diagnos är behandlingen av IPSH i Sverige huvudsakligen begränsad till kortikosteroider (50%) eller ingen medicinsk behandling.

Förekomsten av yrsel vid insjuknandet av PSH har en negativ effekt på hörselförbättringen oavsett om patienten behandlas eller inte.

Ålder har en negativ effekt på hörselförbättringen oavsett behandling eller inte.

I en randomiserad placebokontrollerad klinisk studie kunde ingen positiv effekt av Prednisolon på IPSH påvisas.

En metaanalys av patientdata från den svenska nationella databasen för PSH och den randomiserade kliniska studien för IPSH visade i ett större patientmaterial ingen effekt av Prednisolon på IPSH

Dessa slutsatser torde medföra att kortikosteroidbehandling vid IPSH inte självklart bör fortsätta.

Appendix 67

APPENDIX

Appendix 1. Questionnaire used in the Swedish national database (I, II).

Appendix II. Questionnaire used in the RCT (III).

68 Appendix

APPENDIX I.

Appendix 69

APPENDIX II.

References 71

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