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MANAGEMENT OF CHRONIC OTITIS MEDIA
Dr.Manda.G.K.D.R. Krishna18-12-2012
Surgical goals Achieving a safe ear Eradicating disease Achieving a dry ear Preventing the need for further surgery Improving or at least stabilizing hearing by
reconstruction of the sound conduction mechanism (tympanic membrane and ossicular chain)
Closing any tympanic membrane perforations (if indicated)
Preventing the future development of disease
Preoperative considerations
Allergic rhinitis, paranasal sinus disease, nasopharyngeal mass, and postradiation
sequelae-have to be adressed Imaging -vertigo, otalgia or headache,
sensorineural hearing loss, a positive fistula test, or profuse and purulent otorrhea is evident, or in cases of revision surgery.
Medical management Ototopical agents (sometimes multiple,
concomitant ototopical drops or acetic acid irrigation solutions), aural toilet, and oral antibiotics (when indicated)
Prolonged parenteral antibiotics and daily aural toilet as an alternative to surgery for chronic otitis media without cholesteatoma, with success rate of approximately 90% of patients
Anesthesia Pre anesthetic evaluation
GA Maintenance of a still field Maintenance of hemodynamic stability and
respiratory efficiency Maintenance of cerebral perfusion and oxygenation Facilitation of electrophysiologic monitoring Facilitation of surgical exposure and successful
surgery Prevention of increased intracranial pressure Provision of a smooth, rapid emergence Provision of continuation of all of the above in theintensive care unit Facilitation of postoperative airway management
Drill The handpiece should be well balanced so as toallow the unit to be held like a pen. Unlike a pen,however, the cutting surface of the bur is its side, notits tip. Use the microscope for all drilling. The largest bur possible should be used. Small burs penetrate and injure. Hands should be supported and the drill held
securely. When aggressively fluted burs approximate
irregularities in bone, they have a tendency to skip or“flip.”
Keeping the drilling landscape devoid of ledges/edges helpsdefeat this tendency. One purposeful, continuously pressured drill stroke is more
efficient and safer than multiple inefficient,dangerous strokes. • Keep the field clean. If necessary, stop frequently to irrigate
away bone dust/bleeding. You will injure what you cannot see. The perforation of bone by a bur is to be avoided. Broad saucerization and wide-field exposure allow more light
to reach the field and more room for instrumentation. Working under ledges or in holes is ill-conceived.
Develop the existing anatomy; do not create it. Confident and broad exposure of the anatomy that exists transcends a timid dissection that creates confusing mounds, ledges, and edges that look like anatomy.
Diamond Vs Cutter Use all of your senses when drilling.
Drilling through the aerated temporal bone generates a characteristic chatter.
As the bur approaches the compact bone of the middle and posterior cranial fossae, the tegmen, the external auditory canal, or the bone overlying the lateral venous sinus, a characteristic, high-pitched sound
Curette Like a bur, the cutting surface of the curette is its side. Use the largest curette possible. Curette bone parallel to, never across, the long axis of a
vital structure, for example, the chorda tympani nerve. Sharp instruments require less force and lessen thelikelihood of errors. Cutting strokes should be bold, long, and purposefulrather than whittling. Remove bone fragments and blood for bettervisualization. Never curette upwards from an undersurface. Workfrom visible exposure down.
Closure of Tympanic Membrane Perforations
Paper patch technique -Blake 1887 AgNO3-Roosa 1876 Wullstein -split-thickness skin graft 1952 Heermann -temporalis fascia 1958 Shea- Vein graft 1960
Grafting materials Fat Fascia Perichondrium Periosteum Cartilage Vein prosthetic materials(eg, AlloDerm)
Indications Protection Auditory
Contraindications Absolute Relative
MYRINGOPLASTY TECHNIQUES
Closure of Perforations by a Prosthesis Splinting of Traumatic Perforations Technique of Closure by promotion of
Healing
Myringoplasty
Preoperative evaluation Informed consent Eustachian tube function Age Allergies and sinusitis control Infection control Contralateral ear status Perioperative antibiotics Hearing status & need for hearing aid
Operative technique Patient Positioning Skin Preparation and Sterility Final Preparation Anesthesia
Selection of surgical approach
Acute traumatic perforations are repaired
through a transcanal approach. Posterior perforations are adequately
visualized by an endaural approach. Anterior perforations with margins that
cannotbe seen entirely through the intact external
canalrequire a retroauricular approach.
Lateral and medial placement of graft
Medial and lateral techniques refer to the placement of the graft either medial or lateral to the tympanic membrane remnant-cummings
Overlay
Underlay
Endaural
RETROAURICULAR
canalplasty
GRAFTING
Anterior fascial underlay
Sites of support –underlayAntero inferior
Anterosuperior
Subtotal perforation
Procedure-Anteroinferior
Anterosuperior 1& 2
Subtotal perforation
Complications
Overlay
Risk factors for Re-perforation
Large perforation (Lee P 2002)• 56% success vs. 74% in small perf
Anterior location (Bhat NA 2000)• 67% success vs. 90% in posterior perf
Disease in contralateral ear (Ophir D 1987)
Otorrhea during surgery (Lau T 1986) Middle ear mucosa status (Albu S
1998) Smoking (Becvaroski Z 2001)
Tympanoplasty Eradicate disease in middle ear and to reconstruct the hearing mechanism
without mastoid surgery with or without tympanic membrane
grafting
Tympanoplasty with mastoidectomy
‘‘an operation to eradicate disease in both the mastoid process and middle ear cavity and to reconstruct the middle ear conducting mechanism, with or without tympanic membrane grafting.’’
Indications of TM grafting The control of otorrhea with tympanic
membrane perforation, whether mucoid or purulent
Need for stabilization or improvement in hearing by the reconstruction of the sound-conductive mechanism
An attempt to control or to prevent a secondary acquired cholesteatoma; and
Local membrane defects, such as severely atelectatic or adhesive portions of the tympanic membrane.
Prevention of otorrhea Stabilization or improvement of hearing Removal or prevention of congenital,
iatrogenic, or primary or secondary acquired cholesteatoma
Removal of atelectatic or diseased areas of the tympanic membrane
Classification of Tympanoplasty
Wullstein (1956) Type I tympanoplasty
TM is grafted to an intact ossicular chain Type II tympanoplasty
Malleus is partially eroded TM +/- malleus remnant is grafted to the incus
Type III tympanoplasty Malleus and incus are eroded TM is grafted to the stapes suprastructure
Wullstein classification continued… Type IV tympanoplasty
Stapes suprastructure is eroded but foot plate is mobile
TM is grafted to a mobile foot plate Type V Tympanoplasty
TM is grafted to a fenestration in the horizontal semicircular canal
Classification does not take into account middle ear pathology
Tympanoplasty
Type III tympanoplasty
Type IV Tympanopasty
Classification of Tympanoplasty
Belluci Proposed a dual classification Added status of middle ear
Group I – Dry ear Group II – Occasional drainage Group III – Persistent drainage with mastoiditis Group IV – Persistent drainage and
nasopharyngeal malformation (cleft palate and choanal atresia)
Classification of Tympanoplasty
Austin’s classification Describes the residual ossicular remnants
(M+/I+/S+) – intact ossicular chain (M+/S+) or (M+/S-) – good prognosis (M-/S+) or (M-/S+) – poor prognosis
M – malleus S – stapes I - incus
Postoperative Care Day surgery Mastoid dressing removed Patient instructions
Avoid nose blowing Sneeze with mouth open Avoid heavy lifting or straining Dry ear precautions
One week sutures are removed and ear drops are started
Three weeks, gelfoam is removed from the EAC
2-3 months, postop audiogram is performed
Graft Materials FTSG, STSG
Initial good results Subsequent desquamation and infection with
high delayed failure rate Canal skin
Similar to STSG Vein grafts (Shea)
Atrophy
Graft Materials Temporalis fascia
Hermann (1960) and Storrs (1961) Large quantity No separate incision Sturdy Low metabolic rate
Homograft TM Excellent success similar to fascia Theoretic risk of infectious disease
transmission (prions, HIV) Availability
Cartilage Fascia and perichondrium undergo
atrophy Skin graft: Infection Cartilage
More rigid and resist resorption Good long-term survival Nourished largely by diffusion
Mucosal Traction Theory Mucosal layers of TM and middle ear
linings undergo constant migration ETD creates the initial retraction and
contact between mucosa of TM and ossicles
If mucosa of TM and ossicles are coupled by mucous or fibrous adhesions, migratory forces pull mucosa towards the incus
Mucosal traction plays a stronger role than Eustachian tube dysfunction in forming cholesteatoma
Jackler Otology Update 2006: EBM V
Indications for Cartilage Tympanoplasty
Atelectatic ear Retraction pocket/ Cholesteatoma High Risk Perforation
Revision Anterior perforation > 50% Otorrhea at the time of surgery Bilateral
Techniques Perichondrium/ Cartilage island flap
Tragal cartilage
Cartilage shield technique Conchal cartilage
Palisade technique Tragal cartilage Concha cymba
Inlay Butterfly graft Tragal cartilage
Inlay Butterfly Graft
Tragal Cartilage Harvest Cut on medial side of tragus Leave 2 mm tragal cartilage
for cosmesis Abundance: 15 x 10 mm Flat ~ 1 mm thickness Perichondrium from the side
away from the EAC is removed
paliside
Cartilage Tympanoplasty
Cartilage Tympanoplasty
Cartilage Tympanoplasty
Cartilage Tympanoplasty
Tympanoplasty in Children Controversial Considered less successful than adults
Higher incidence of ETD and otitis media Wide range of success rates
35% to 93% Tos and Lau (1989)
Found comparable success rates compared to adults for all ages in children (92%)
Helps to lessen progression of ossicular pathology
Tympanoplasty in Children Manning
78% success Deskin and Vrabec (1999)
Meta-analysis of all common variables assoc. w/ success
Found only advancing age was statistically associated with improved outcomes.
Complications Infection
Poor aseptic technique Prior contamination Graft failure is associated with postop
infection Graft failure
Infection Inadequate packing (anterior mesotympanum) Inadequate overlay of graft with TM remnant
(underlay)
Complications Chondritis Injury to the chorda tympani nerve SNHL and vertigo
Excessive manipulation of the ossicles Increased conductive hearing loss
Unrecognized eroded ISJ Blunting
Thick graft extending onto the anterior canal wall in lateral grafting
Lateralization of the TM from the malleus handle External auditory canal stenosis
Lateral grafting
Results – closure of perforations
1992 – Smyth (Toynbee Memorial Lecture) Stated that most series report 90% success
Majority of studies have only one year f/u Most do not report atelectatic pockets
Halik and Smyth 60% success in revision cases Found improved results in patients with dry ears Similar success with temporalis fascia versus
homograft Worse results with anterior perforations
Recommend using fascia Anterior TM is less vascular Fascia less susceptible to anoxia and is less antigenic than
homograft
Results – hearing Albu et al.
Three most important prognostic indicators Status of the middle is the most important
predictive factor Presence of the handle of the malleus Perforations > 50%
Halik and Smyth 80% success rate closing ABG to within 10 dB
at 5 years
Results – overlay grafting Sheehy and Anderson (1980)
Compared 472 overlay 97% success with fascia grafts 84% success with canal skin 1.3% complication rate
Anterior blunting Lateralization
80% had ABG within 10 dB
Results – overlay vs. underlay
Doyle et al. (1972) Compared 52 overlay to 79 underlay at a
teaching institution Overlay
36% re-perforation 27% with hearing improvement (15db ABG or
better) Underlay
14% re-perforation 62% hearing improvement
> complication rate with overlay group
Results – overlay vs. underlay
Doyle et al. (1972) Conclusions
In experienced hands either technique can be equally successful
Residents and otolaryngologist of limited experience Medial grafting gives better healing and fewer
complications All cases utilized endaural approach with is
more techniquely demanding
Results – overlay vs. underlay
Rizer (1997) Compared 551 underlay to 158 overlay
Closure in 88.8% of underlay versus 95.6% of overlay
Closure of ABG to 10 dB or less in 84.9% of underlay vs. 80.4% of overlay
Similar complication rates
Results – overlay vs. underlay
Rizer (1997) Both groups – no relationship in re-perforation
with: Age of patient Perforation size or location Middle ear status Presence of cholesteatoma
Conclusion Tympanoplasty has a high rate of success in closing
tympanic membrane perforations and improving hearing
Patients should be chosen carefully based on the indications discussed and attempts at attaining a dry ear prior to surgery should be made
Patients should be thoroughly counseled preoperatively about the expectations and goals of the surgery
Tympanoplasty in the pediatric age group is controversial
Both underlay and overlay techniques for grafting are effective
Surgeon ‘s choice
CHOLESTEATOMA
Cholesteatoma Spread Predictable in that they are channeled
along characteristic pathways by: Ligaments Folds Ossicles
Common Sites of Cholesteatoma Origin
Posterior epitympanum
Posterior mesotympanum
Anterior epitympanum
Cholesteatoma Spread Posterior epitympanic cholesteatoma
passing through superior incudal space and aditus ad antrum
Cholesteatoma Spread Posterior mesotympanic cholesteatoma
invading the sinus tympani and facial recess
Cholesteatoma Spread Anterior epitympanic cholesteatoma with
extension to geniculate ganglion
PATIENT EVALUATION
Patient Evaluation History
Detailed otologic history Hearing loss Otorrhea Otalgia Nasal obstruction Tinnitus Vertigo
Previous history of middle ear disease Chronic otitis media Tympanic membrane perforation Prior surgery
Patient Evaluation Head and neck examination Otologic examination
Otomicroscopy is essential in evaluating the extent of disease
Clean ear thoroughly of otorrhea and debris with cotton-tipped applicators or suction
Culture wet, infected ears and treat with topical and/or oral antibiotics
Pneumatic otoscopy should be performed in every patient with cholesteatoma Positive fistula (pneumatic otoscopy will result in
nystagmus and vertigo) response suggests erosion of the semicircular canals or cochlea
Patient Evaluation Hearing evaluation to assess for
conductive hearing loss Pure tone audiometry with air and bone
conduction Speech reception thresholds Word recognition
512Hz tuning fork exam Always correlate with audiometry results
Tympanometry May suggest decreased compliance or TM
perforation
Patient Evaluation Degree of conductive loss will vary
considerably depending on the extent of disease Moderate conductive deficit in excess of 40 dB
indicates ossicular discontinuity Usually from erosion of the long process of the
incus or capitulum of the stapes Mild conductive deafness may be present with
extensive disease if cholesteatoma sac transmits sound directly to stapes or footplate
Patient Evaluation Preoperative imaging with computed
tomographies (CTs) of temporal bones (2mm -section without contrast in axial and coronal planes) Allows for evaluation of anatomy May reveal evidence of the extent of the
disease Screen for asymptomatic complications
Patient Evaluation CT is not essential for preoperative
evaluation Should be obtained for:
Revision cases due to altered landmarks from previous surgery
Chronic suppurative otitis media Suspected congenital abnormalities Cases of cholesteatoma in which
sensorineural hearing loss, vestibular symptoms, or other complication evidence exists
Patient Evaluation Preoperative counseling is an absolute
necessity prior to surgery Primary objective of surgery is a safe dry
ear which is accomplished by: Treating all supervening complications Removing diseased bone, mucosa, granulation
polyps, and cholesteatoma Preserving as much normal anatomy as
possible Improvement of hearing is a secondary
goal
Patient Evaluation Possible adverse outcomes must be
discussed Facial paralysis Vertigo Further hearing loss Tinnitus
Patient should understand that long-term follow-up will be necessary and that they may need additional surgeries
Preventative Management Tympanostomy tube for early retraction
pockets
Surgical exploration for retraction persistence
Cholesteatoma Management
Treated surgically with primary goal of total eradication of cholesteatoma to obtain a safe and dry ear
Patients with unacceptable risk of anesthesia need local care
Surgical Management Canal-wall-down procedures (CWD) Canal-wall-up procedure (CWU) Transcanal anterior atticotomy Bondy modified radical procedure
Canal-Wall-Down Prior to the advent of the tympanoplasty,
all cholesteatoma surgery was performed using CWD approach
Procedure involves: Taking down posterior canal wall to level of
vertical facial nerve Exteriorizing the mastoid into external
auditory canal Epitympanum is obliterated with removal
of scutum, head of malleus and incus
Canal-Wall-Down Classic CWD operation is the modified
radical mastoidectomy in which middle ear space is preserved
Radical mastoidectomy is CWD operation in which: Middle ear space is eliminated Eustachian tube is plugged
Meatoplasty should be large enough to allow good aeration of mastoid cavity and permit easy visualization to facilitate postoperative care and self cleaning
Canal-Wall-Down Indications for CWD approach:
Cholesteatoma in an only hearing ear Significant erosion of the posterior bony canal
wall History of vertigo suggesting a labyrinthine
fistula Recurrent cholesteatoma after canal-wall-up
surgery Poor eustachian tube function Sclerotic mastoid with limited access to
epitympanum
Canal-Wall-Down Advantages:
Residual disease is easily detected Recurrent disease is rare Facial recess is exteriorized
Disadvantages: Open cavity created
Takes longer to heal Mastoid bowl maintenance can be a lifelong
problem Shallow middle ear space makes OCR difficult Dry ear precautions are essential
Canal-Wall-Down
Canal-Wall-Down
Canal-Wall-Down
Canal-Wall-Down
Canal-Wall-Down
Canal-Wall-Up CWU procedure developed to avoid
problems and maintenance necessary with CWD procedures
CWU consists of preservation of posterior bony external auditory canal wall during simple mastoidectomy with or without a posterior tympanotomy
Staged procedure often necessary with a scheduled second look operation at 6 to 18 months for: Removal of residual cholesteatoma Ossicular chain reconstruction if necessary
Canal-Wall-Up CWU may be indicated in patients with
large pneumatized mastoid and well aerated middle ear space Suggests good eustachian tube function
CWU procedures are contraindicated in: Only hearing ear Patients with labyrinthine fistula Poor eustachian tube function
Canal-Wall-Up Advantages:
Rapid healing time Easier long-term care Hearing aids easier to fit No water precautions
Disadvantages: Technically more difficult Staged operation often necessary Recurrent disease possible Residual disease harder to detect
Canal-Wall-Up
Canal-Wall-Up
Transcanal Anterior Atticotomy Indicated for limited cholesteatoma
involving middle ear, ossicular chain, and epitympanum
If extent of the cholesteatoma is unknown approach can be combined with CWU mastoidectomy or extended to CWD procedure
Transcanal Anterior Atticotomy Procedure involves:
Elevation of tympanomeatal flap via endaural incision with removal of scutum to limits of the cholesteatoma
Aditus obliteration with muscle, fascia, cartilage or bone prior to reconstruction of the middle ear space
Reconstruction of lateral attic wall with bone or cartilage is optional May lead to retraction disease and possible
recurrence in patients with poor eustachian tube function
Transcanal Anterior Atticotomy
Bondy Modified Radical Procedure
Useful for attic and mastoid cholesteatoma that does not involve middle ear space and lateral to ossicles
Like modern modified radical mastoidectomy with exception that middle ear space is not entered
Mastoid should be poorly developed for creation of a small cavity
Eustachian tube function should be adequate with intact pars tensa and aerated middle ear space.
Rarely used today
Canal Wall Status In 2002 Shohet et. al. reports recidivism
rates with CWU as high as Adults = 36% Children = 67%
Approximately 30% of cases for cholesteatoma will be CWD House Ear Institute 1982 St. Joseph’s Hospital in Phoenix, AZ 2003
Canal Wall Status Syms et. al. examined surgical approach
to manage cholesteatoma- retrospective review of 486 cases in 2003 68.5% CWU: 31.5% CWD CWU had “second look operation”
Residual cholesteatoma found in 26.9% second procedures
Residual cholesteatoma found in 2.7% third procedures
Canal Wall Status Kos et. al. examined long-term
implications of CWD- retrospective review in 2004 259 cases with follow-up range of 1 to 24
years (mean = 7 years) Recurrent cholesteatoma in 6.1% TM perforation in 7.3% Dry, self-cleaning ears in 95% Otorrhea in 5%
Canal Wall Status Kos et. al. (continued)
Hearing threshold Improved in 30.7% Unchanged in 41.3% Decreased in 28%
Sensorineural hearing loss greater than 60dB in 2 patients
Facial paralysis in 1 patient Vertigo in 4 patients
Novel Techniques In 2005 Gantz et. al. reported 130 cases
of canal wall reconstruction tympanomastoidectomy with mastoid obliteration No evidence of recurrence = 98.5% Recurrence treated with CWD (1.5%) Second look ossiculoplasty in 78% Post-operative wound infection was 14.3% for
first 42 patients Decreased rate to 4.5% in last 88 patients with 2
days of post-operative IV antibiotics
Novel Techniques Canal Wall Reconstruction technique
Complete cortical mastoidectomy with opening of facial recess and removal of incus and malleus head
Posterior canal wall skin elevated, annulus elevated
Microsagittal saw used to cut posterior canal wall
Cholesteatoma removed Posterior canal wall bone replaced
Cortical bone chips used to block attic and mastoid from tympanum
Bone wax holds bone chips in place
Novel Techniques
Novel Techniques In 2005, Godinho et. al. reported 42
cases of Canal Wall Window (CWW) performed for pediatric cholesteatoma CWW compared to CWU and CWD
CWW converted to CWD in 14% Dry ear results
CWW = 94%, CWD = 92%, CWU = 90% Recidivation rate at 1 year
CWW = 19.5%, CWD = 0%, CWU = 7.7% CWW provided similar post-operative hearing to
CWU, rather than increased air-bone gap seen with CWD
Novel Techniques CWW effective for posterior superior
cholesteatoma Increases visibility Conduit for instrument manipulation
CWW technique CWU mastoidectomy performed Lateral epitympanotomy Slit drilled from lateral cortex to medial aspect
of canal wall at annulus
Novel Techniques
Novel Techniques CWW reconstruction
Tragal cartilage placed in defect after scoring proximal perichondrium and cartilage
Cortical bone graft may be used as an alternative
Novel Techniques
Conclusions Pathogenesis of cholesteatoma remains
uncertain Essential to possess basic knowledge of the
important anatomic and functional characteristics of the middle ear for successful management of cholesteatomas
Careful and thorough evaluations are the key to early diagnosis and treatment
Treatment is surgical with primary goal to eradicate disease and provide a safe and dry ear
Surgical approaches must be customized to each patient depending on extent of disease
Surgeon must be aware of serious and potentially life-threatening complications of cholesteatomas
Conclusion Treatment should be tailored to case Absolute CWD indications
Cholesteatoma in an only hearing ear Significant erosion of the posterior bony canal
wall History of vertigo suggesting a labyrinthine
fistula Recurrent cholesteatoma after canal-wall-up
surgery Poor eustachian tube function Sclerotic mastoid with limited access to
epitympanum No harm in starting CWU and converting
to CWD as necessary
Introduction Etiology of ossicular
disruption Anatomy Pathophysiology Operative Techniques Complications
Etiology Fixation
Malleus head ankylosis (idiopathic) Ossicular tympanosclerosis Scar bands in chronic otitis media
Discontinuity Trauma Erosion by chronic otitis media/ cholesteatoma
(most common) Eroded incudostapedial joint (80% of patients) Absent incus Absent incus and stapes superstructure
Introduction Etiology of ossicular
disruption Anatomy Pathophysiology Operative Techniques Complications
Anatomy The normal
conducting apparatus of the middle ear consists of an intact tympanic membrane and three ossicles connected in series.
Any disruption of these components can cause conductive hearing deficits.
Tympanic Membrane The orientation of the
TM is slightly oblique to the sagittal plane; the TM is roughly conical, pointing medially.
The handle of the malleus is firmly attached to the medial aspect of the TM.
The TM is divided into two parts: the pars flaccida (the portion superior to the insertion of the manubrium) and the pars tensa.
The point at which the inferior end of the manubrium inserts into the TM is called the umbo.
Malleus The malleus has two main
parts: the manubrium, which adheres to the tympanic membrane, and the head, which articulates with the incus. The malleus head lies in the epitympanic recess.
The manubrium also has two processes: one anterior and one lateral
The region between the manubrium and the head is called the neck of the malleus.
The chorda tympani crosses the medial surface of the malleus neck.
Incus The incus is divided into
3 principal parts: a body and two processes (named short and long, respectively).
The head of the incus articulates with the head of the malleus in the epitympanic recess.
At the end of the long process of the incus is a small region called the lenticular process. The lenticular process articulates with the head of the stapes.
The short process of the incus is attached to the cavity wall by the posterior incudal ligament.
Stapes As the name implies,
the stapes looks like a stirrup. It has four components: a footplate, two crura (posterior and anterior), and a head.
The head of the stapes articulates with the lenticular process of the incus.
The footplate of the stapes covers the oval window.
Introduction Anatomy Etiology of ossicular
disruption Pathophysiology Operative Techniques Complications
Pathophysiology The acoustic resistance to the passage
of sound through a medium is termed impedance.
The transduction of vibratory energy from the air in the external auditory canal (low impedance) to the cochlear fluids (high impedance) is possible as a result of the impedance-matching function of the middle ear.
Three levers accomplish the required pressure transformation for transduction.
Catenary Lever The attachment of the tympanic
membrane at the annulus amplifies the energy at the malleus because of the elastic properties of the stretched drumhead fibers.
Because the annular bone surrounding the tympanic membrane is immobile, sound energy is directed away from the edges of the drum and toward the center of the drum.
The malleus receives the redirected sound energy from the edge of the drum because of the central location of the manubrium.
Catenery Lever In physics and
geometry, the catenary is the theoretical shape a hanging chain or cable will assume when supported at its ends and acted on only by its own weight. The curve is a hyperbolic cosine which has a U-like shape, similar in appearance to a parabola.
Ossicular Lever The malleus and incus acting as a unit, rotate around an axis running between the
anterior mallear ligament and the incudal ligament. The gain of the ossicular lever is the length of the manubrium of the malleus divided by
the length of the long process of the incus (approximately 1.3:1). The ossicular lever taken alone produces a small mechanical advantage for sound
transmission. The catenary lever is tightly coupled to the ossicular lever, because the tympanic
membrane is extensively adherent to the malleus handle. Corrected calculations reveal a combined catenary-ossicular lever ratio of 1:2.3.
Hydraulic Lever The hydraulic lever acts because of the
size difference between the tympanic membrane and the stapes footplate.
Sound pressure collected over the area of the tympanic membrane and transmitted to the area of the smaller footplate results in an increase in force proportional to the ratio of the areas
The average ratio has been calculated to be 20.8:1.
Taking the three levers together, the middle ear offers a theoretical gain of approximately 34 dB
Ossicular Coupling Ossicular coupling refers to the true
sound pressure gain that occurs through the actions of the tympanic membrane and the ossicular chain.
The true gain of the middle ear is less than the theorized 34 dB
The pressure gain provided by the normal middle ear with ossicular coupling is frequency dependent.
The actual mean middle ear gain is 20 dB at 250-500 hertz (Hz), reaching a maximum of 25 dB at 1 kilohertz (kHz), and then decreasing at about 6 dB per octave at frequencies above 1 kHz.
Ossicular Coupling The changes in gain above 1 kHz are caused by
portions of the tympanic membrane moving differently than other portions, depending on the frequency of vibration. At low frequencies, the entire tympanic membrane moves in one phase. Above 1 kHz, the tympanic membrane divides into smaller vibrating portions that vibrate at different phases.
Another factor is slippage of the ossicular chain, especially at frequencies above 1-2 kHz. Slippage is due to the translational movement in the rotational axis of the ossicles or flexion in the ossicular joints.
In addition, some energy is lost because of the forces needed to overcome the stiffness and mass of the tympanic membrane and ossicular chain.
Middle Ear Aeration Ossicular coupling is impaired when the middle ear space
(including the mastoid cavity) is reduced. The difference in pressures between the external auditory
canal and the middle ear facilitates tympanic membrane motion.
In the normal ear, the middle ear air pressure is less than the pressure in the external canal.
When the middle ear space is reduced (eg, by chronic ear disease or canal wall down surgery), the impedance and pressure of the middle ear increase relative to the external canal because the impedance of the middle ear space varies inversely with its volume.
This reduction in pressure difference leads to a subsequent reduction in tympanic membrane and ossicular motion.
The minimal amount of air required to maintain ossicular coupling within 10 dB of normal has been estimated to be 0.5 mL.
Pathophysiology Austin (1978) identified five categories of
anatomic defect and described each within the context of the associated prototypic hearing loss.
The first category, tympanic membrane perforation with undisturbed ossicular continuity produced a hearing loss that was linearly proportional to the size of the perforation (loss of areal ratio + loss of catenary lever).
The degree of hearing loss, flat across speech frequencies, was not altered by the location of the perforation on the drumhead.
Pathophysiology The second category, tympanic
membrane perforation combined with ossicular disruption occurred in approximately 60% of Austin's patients and was the most common form of conductive hearing loss requiring surgical therapy.
The incudostapedial joint was the most vulnerable ossicular articulation.
Pathophysiology The third category, total loss of the
tympanic membrane and ossicles created a condition wherein sound pressure contacted the oval and round windows simultaneously, resulting in partial phase cancellation of the sound wave in the cochlear fluids.
Conductive hearing loss was flat across speech frequencies and averaged 50 dB
More complete phase cancellation caused increased hearing loss compared with patients with partial perforations.
Pathophysiology The fourth category included those patients with
ossicular disruption behind an intact tympanic membrane. This defect resulted in a maximal conductive hearing loss of 60 dB.
The intact eardrum reflected sound energy back into the external auditory canal, causing an additional 17-dB conductive loss above what was expected from removal of the hydraulic and catenary-ossicular lever action.
The decreased sound pressure also reached the round and oval windows nearly simultaneously, inducing phase cancellation in the labyrinthine fluids.
Pathophysiology The fifth category described a variety of
congenital malformations with ossicular disruption and closure of the oval window
Also included were cases of obliterative otosclerosis with closure of the oval and round windows behind an intact drum.
The expected flat loss from such a defect is 60 dB.
Preoperative Assessment The goal of ossicular chain reconstruction is
better hearing, most typically for conversational speech.
Patient selection for ossicular reconstruction is largely based on the preoperative audiogram and on the potential to regain serviceable hearing.
Bringing the operative ear to within 15 dB of the contralateral ear will enhance binaural input to auditory centers; A patient's perceived hearing improvement is best when the hearing level of the poorer-hearing ear is raised to a level close to that of the better-hearing ear.
In patients with severe mixed hearing loss, ossicular reconstruction can be considered, because it may enhance the use of amplification.
Contraindications Acute infection of the ear is the only true
contraindication. Acute infection will most likely result in
poor healing, prosthesis extrusion, or both.
Relative contraindications include persistent middle ear mucosal disease, tympanic membrane perforation, and repeated unsuccessful use of the same or similar prostheses.
Malleus Head Fixation Idiopathic malleus head fixation occurs in the
epitympanum 2 different surgical techniques are used in the treatment
of malleus fixation syndrome. The attical fixation can be removed via a transmastoid
approach without disruption of the ossicular chain. Alternatiely, an ossiculoplasty can be performed via a
transcanal approach, removing the malleus head with the incus and reconstructing by incus interposition or by PORP.
Martin (2009) reported a retrospective study including 24 patients (25 ears).
The study concluded that there was no statistically significant difference between the 2 surgical techniques when post-op hearing was considered.
Incus Erosion Some form or degree of incus deficiency
is the most common ossicular defect encountered.
The goal of surgery is to reestablish the mechanical connection between an intact tympanic membrane and the oval window.
This can be accomplished by a variety of techniques utilizing a variety of materials.
Mildly eroded incus The incudostapedial joint and the
lenticular process of the incus are the most common sites of ossicular discontinuity.
This defect can lead to an air-bone gap of up to 60 dB.
When erosion is limited to the most distal portion of the incus and when the incus and the malleus are mobile, a limited reconstruction can be performed.
Mildly eroded incus Applebaum designed a hydroxyapatite prosthesis for
defects of the incus long process. The Applebaum prosthesis is a rectangular piece of
hydroxyapatite with a groove through the proximal end extending the length of the rectangle The groove stops short of penetrating the distal end of the rectangular prosthesis. At this distal end of the groove, a circular hole passes through the floor of the groove. The groove is designed to accommodate the remnant of the incus long process. The circular hole receives the stapes capitulum.
The prosthesis is placed by gently lifting the long process of the incus and sliding it into the groove. Then the hole of the prosthesis is placed onto the stapes head. This procedure results in a stable connection requiring no further packing or tissue adhesion.
Mildly eroded incus Advantages of the Applebaum prosthesis
include: The prosthesis reliably bridges incus long
process defects of up to 3 mm. It does not tend to loosen and lose continuity over time.
The prosthesis avoids technical difficulty and time involved in constructing bone or cartilage bridges.
It precludes removal of the incus for refashioning, and consequently it spares unnecessary destruction of the incudomalleal joint.
The prosthesis can be immediately available in the operating room, saving the patient from unnecessary anesthesia time.
Absent Incus More extensive erosion of the incus
requires a more extensive reconstruction. Ossicular continuity can be restored
between the stapes and manubrium of the malleus (if present).
Alternatively, a “strut” or “columella” may be formed by an implant bridging from the capitulum or footplate to the tympanic membrane
Autograft Interposition of incus body as a bridge
between the stapes and the mallues was the original ossicular reconstruction surgery.
If the incus is unavailable, the malleus head may be used.
This type of autograft is considered by some to be the procedure of choice.
Autograft Incus interposition should only be
considered when the angle between the long axis of the stapes capitulum and malleus handle is favorable (preferably <30°).
Angles more than 45° prevent proper sound transfer between the stapes and malleus.
Specifically, some sound energy is converted into an inefficient rocking motion at the footplate if the manubrium is too far anterior to the stapes.
Autograft Disadvantages
Prolonged operative time Displacement Complete resorption Possibility of autograft harboring microscopic
cholesteatoma Disease process may have eroded available ossicles Poor fit if the stapes superstructure is absent
Advantages Low extrusion rate No risk of transmitting disease Low cost Biocompatibility No necessity for reconstitution Fully biocompatible
Homograft Irradiated homograft ossicles and
cartilage were first introduced in the 1960s in an attempt to overcome some of the disadvantages of autograft implants.
These have now fallen out of favor Disadvantages
Must be stored in special conditions Risk of transmitting diseases (eg, AIDS,
Creutzfeldt-Jakob disease). Advantages
Same as autograft
Allograft A variety of synthetic materials have
been used to manufacture a variety of prostheses.
These allografts are the most commonly used materials for ossicular reconstruction today.
Disadvantages More expensive Higher extrusion rate (controversial)
Advantages Readily available Presculpted
Plastipore and Polycel In the late 1970s, a high-density polyethylene
sponge (HDPS) that had nonreactive properties was developed. HDPS has sufficient porosity to encourage tissue ingrowth.
The original form was a machined-tooled prosthesis (Plasti-Pore); a more versatile manufactured thermal-fused HDPS (Polycel) arrived later. This latter form permitted coupling with other materials, such as stainless steel, thus lending itself to a wide variety of prosthetic designs.
Clinical experience has shown the necessity of covering these HDPS alloplasts with cartilage to minimize the incidence of extrusion. Extrusion rates have averaged 3-5% in large series with 5-10 years of follow-up monitoring.
Hydroxyapatite Hydroxylapatite is another bioactive material used for
middle ear reconstruction. The nonporous and homogenous nature of dense hydroxylapatite resists penetration by granulation tissue.
Hydroxylapatite is a polycrystalline calcium phosphate ceramic that has the same chemical composition as bone.
It forms a direct bond with bone at the hydroxylapatite/tissue interface- If placed next to the scutum, osseointegration can occur, with subsequent conductive hearing loss.
With time, hydroxylapatite implants gradually become completely covered by an epithelial layer. The final epithelial layer contains all cell types characteristic for the middle ear. indicating good biocompatibility of the implant material.
Titanium Titanium is another common alloplastic material. Studies
in rabbits have shown that within 28 days after implantation, a thin, noninflamed, even layer of epithelium forms over the inserted implant. Similar results in human studies have shown the same type of reactivity. Titanium forms a biostable titanium oxide layer when combined with oxygen.
The properties of titanium make it possible to manufacture an extremely fine and light prosthesis with substantial rigidity in the shaft.
Furthermore, differential processing of the material surfaces triggers various tissue reactions. For example, rough-milled surfaces are most appropriate in areas that contact cartilage or the stapes head or footplate.
Conversely, the smoother the surface, the less connective tissue reaction occurs, and the epithelial covering is minimized.
Titanium As far back as 1993, a group of surgeons
designed the total (Arial) prosthesis and the partial (Bell) prosthesis.
These are available commercially from Kurz.
In 1996, Spiggle and Theis introduced new titanium prostheses that can be trimmed intraoperatively to the appropriate length
Which Prosthesis? An otologic surgeon must choose his
prosthesis based on the best chance of successful hearing restoration and the lowest chance of complications.
Defining Success Attempts have been made to standardize
reporting 1995 guidelines of the AAO-CHE Pre and postoperative air-conduction and
bone-conduction thresholds are measured at 4 designated frequencies (0.5, 1, 2, and 3 kHz), then averaged
Success is defined as a mean postoperative air-bone gap of less than 20 dB and is the main outcome considered for this talk
Prognostic Factors It is clear that optimal results depend not
only on the qualities of the prosthesis, but also on the environment in which it is placed and the surgical techniques used.
Prognostic Factors Austin (1972) defined four groups in
which the incus had been partially or completely eroded:
A, malleus handle present, stapes superstructure present (60% occurrence)
B, malleus handle present, stapes superstructure absent (23%)
C, malleus handle absent, stapes superstructure present (8%)
D, malleus handle absent, stapes superstructure absent (8%)
Prognostic Factors Kartush (1994) proposed a scoring
system called the middle ear risk index (MERI) to form an index score to determine the probability of success in hearing restoration surgery.
MERI is used to describe the preoperative middle ear environment at the time of ossiculoplasty
It incorporates different classifications of middle ear disease and ossicular status, including Austin’s
Prognostic Factors Dornhoffer 2001, unsatisfied with the clinical
correlation of the MERI, further analyzed clinical data.
200 ears, reconstructed with HAPEX PORP or TORP, were analyzed.
Ossicular chain status, mucosal status, otorrhea, +/- mastoidectomy, and revision surgery were all significant prognosticators.
Of note, presence of the stapes superstructure was not influential.
Dornhoffer proposed the Ossicular Outcomes Parameters Staging (OOPS)
Prognostic Factors De Vos (2007) reported on 149 ears Multivariate statistical analysis identified the
predictive value of the presence or absence of the malleus handle and the mucosal status of the middle ear mucosa in the prognosis of ossiculoplasties.
They did not show predictive value in CWU mastoidectomy, otorrhea, myringitis, or length of the prosthesis.
Best results were obtained in the Austin A (S+M+) and B (S-M+) classifications, with no difference between the two.
This contrasts with previous thoughts on the importance of the stapes superstructure.
All three studies of prognostic factors identify middle ear mucosal status and presence of malleus handle as important predictors of successful hearing restoration.
Options for POR and TOR With such a variety of options and materials
available for reconstructing the ossicular chain, the otologic surgeon must consider using the method that provides the best hearing result with the least chance of complications.
The ideal study for comparison of techniques would be a single surgeon directly comparing techniques or materials on patients who had been risk stratified by a validated prognostic index, with reporting of complication rates and long-term follow up.
This study does not exist. This talk will review studies published in the
past decade in order to assist the otologic surgeon in making an informed decision about which technique to use.
Pasha Pasha (2000) studied 33 consecutive
cases of OCR with HA PORP, TORP, or Kartush incus strut.
Hearing results, based on postoperative mean ABG, were best when incus struts were used.
Patients receiving incus struts had lower MERI scores in general, and, of course, had malleus handle present.
3 PORPs extruded; no incus struts or TORPs extruded.
Cartilage caps were not placed over the prostheses.
POR TOR
Interposition Titanium PORP Non-titanium PORP
Titanium TORP Non-titaium TORP
Pasha (2000)
House (2001) 63% 58%Iurato review (2001) 84% 82%Iurato study (2001) 85%Dalchow (2001) 76% 76%Ho (2003) 64% 45%Neff (2003) 89%
POR TORInterposition Titanium PORP Non-titanium
PORPTitanium TORP Non-titaium
TORP
Rondini-Gilli (2003)
Hillman (2003) 45% 60%Gardner (2004) 70% 48% 44% 21%Martin (2004) 68% 40%O’Reilly (2005) 66%Schmerber (2006) 77% 52%Truy (2007) 72% 67%
Success RatesPOR TOR
Interposition Titanium PORP Non-titanium PORP
Titanium TORP Non-titaium TORP
Vassbotn (2007) 77% 89%Siddiq (2007) 85% 46%DeVos (2007) 60% 60%Coffey (2008) 82% 50% 74% 50%Emir (2008) 58% 56%Neudert (2009) 66% 66%Mean 72% 70% 61% 62% 43%
Conclusions A standardized prognostic classification
must be adopted in order to compare future results across multiple studies
A cartilage cap must be used when an allograft PORP or TORP is used.
Extrusion/ diplacement rates of allograft prostheses are between 0.5-10% and are lower when a cartilage cap is used.
Conclusions Across the past 10 years of published
reports, based on anecdotal data, titanium PORP yields approximately equivalent hearing results to incus interposition.
TORP reconstruction most probably yields a poorer hearing result than PORP when all cases are considered.
Considering the technical skill needed to successfully perform incus interposition, a general otolaryngolist should opt for titanium reconstruction prosthesis for OCR.
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