(Morrison) Tension Muscular Laringea Extrinsica

INTRODUCTION

Patients with voice disorders are often classifiedinto groups having organic and nonorganic dyspho-nia. Most organic causes are easy to identify by his-

tory and laryngoscopic examination. Nonorganic, of-ten termed “functional,” dysphonia is frequently thediagnosis made by most general otolaryngologistswhen there is no demonstrable organic lesion.

Muscle misuse dysphonia (MMD) is probably themost common nonorganic cause of voice disordersdiagnosed in most voice clinics today and may be themost common cause of chronic dysphonia experi-enced by humans. Up to 60% to 70% of patients insome voice clinics have been identified as havingMMD.1 The diagnosis of MMD is based on case his-tory of vocal misuse or abuse and the videostrobo-laryngoscopic finding of normal vocal fold mucosa

Journal of VoiceVol. 16, No. 3, pp. 333–343© 2002 The Voice Foundation

Extrinsic Laryngeal Muscular Tension in Patients with Voice Disorders

*Thana Angsuwarangsee and †Murray Morrison

*Division of Otolaryngology and Department of Health Care and Epidemiology, University of British Columbia,Vancouver, Canada, and Department of Otolaryngology, Mahidol University, Bangkok, Thailand; †Division of

Otolaryngology, University of British Columbia, Vancouver, Canada

Summary: The objective of this study was to establish a standard clinical eval-uation tool for assessment by palpation of extrinsic laryngeal muscular tension(ELMT) and investigate the relationship between ELMT and different voice dis-order diagnosis categories, particularly muscle misuse dysphonia (MMD), andthe presence or absence of gastroesophageal reflux (GER). A palpation tech-nique and tension grading system for four separate muscle groups (suprahyoid,thyrohyoid, cricothyroid, and pharyngolaryngeal) were established. 465 pa-tients, 65% female and 35% male, were assessed sequentially and ELMT resultswere analyzed in relation to diagnosis and reflux status. A strong relationshipwas found between thyrohyoid muscle tension and both GER and MMD (p ≤0.01). Thyrohyoid muscle tension is the only group that demonstrated a signif-icant relationship with MMD. No significant difference in the ELMT scores wasfound between GER and non-GER patients, although a possible causal rela-tionship was found between MMD type 3 and reflux. It is postulated that pal-pation of extrinsic laryngeal muscles can yield important information about in-ternal laryngeal postures and diagnosis of muscle misuse voice disorders,particularly MMD type 3 (anteroposterior supraglottic compression). Integra-tion of this technique into routine laryngeal examination can be a significant aidto diagnostic accuracy. Key Words: Muscular tension dysphonia—Laryngealpalpation—Voice disorder diagnosis.

Accepted for publication December 10, 2001.Address correspondence and reprint requests to Dr. M.D.

Morrison, Division of Otolaryngology, Vancouver GeneralHospital, 805 West 12th Ave., Vancouver BC Canada V5Z1M9.

Presented to the Collegium Medicorum Theatri (COMET)Aspen, CO, June 26, 1999.

e-mail: [email protected]

333

and movement, usually with some specific abnormallaryngeal posture.2 Videostrobolaryngoscopy is es-sential in distinguishing MMD from subtle vocal foldlesions such as sulcus vocalis or submucosal scarring.

Treatment options for MMD consist of voice ther-apy, psychotherapy, manual therapy, and treatment ofassociated disorders. Voice therapy is the main thera-py for MMD, but manual therapy, if done correctly,can accelerate improvement and shorten the courseof therapy.3 Identifying specific extrinsic laryngealmuscle groups with abnormally high tension and ap-plying manual therapy to that specific group of mus-cles may reduce the number of visits for this therapy.Treatment of associated causes or aggravating factorssuch as gastroesophageal reflux disorders (GER) isalso an essential part of the treatment plan.

Rationale for extrinsic laryngeal musclepalpation in evaluation of voice disorders

There is little doubt that the external laryngealmuscles contribute significantly to voice production.In the course of more than 100 years of research anumber of theoretical explanations for the role of theextrinsic muscles and other external mechanisms inphonatory function have emerged. This topic was re-viewed by Vilkman et al in 1996.4 However, to thebest of our knowledge there have been no systematicgrading criteria established for clinical application,perhaps due to a lack of clinical data relating extrin-sic laryngeal muscle tension (ELMT) to the diagno-sis in voice disorders. If there are unique patterns ofELMT in different categories of voice disorders,measuring it will be a useful clinical tool. The voiceclinician will find ELMT helpful in the diagnosis ofMMD and speech-language pathologists, singingteachers, and the patients themselves can use ELMTfor monitoring clinical improvement, and as biofeed-back during therapy exercises.

Gastroesophageal reflux (GER) is a known causeand aggravating factor of laryngeal and voice disor-ders,5 and we feel that this is possibly due in part to re-flux-generated tense intrinsic and extrinsic laryngealmusculature. Patients assessed in our clinic are given aprimary diagnosis, and often a secondary diagnosis isassigned as well. All patients with proven or stronglysuspected GER are listed as having reflux as the sec-ondary diagnosis. Since esophageal stimulation isshown to produce a reflex laryngeal contraction,6 andglobus sensation is thought to be due to reflux-in-

duced pharyngeal muscle tension,5 it seems importantto question whether or not the pharyngeal constrictortension is palpably higher in reflux patients.

OBJECTIVE

The purpose of this study is to investigate the rela-tionship between extrinsic laryngeal muscle tension(ELMT) and different diagnosis voice disorder cate-gories, particularly muscle misuse dysphonia(MMD), and the relationship of gastroesophageal re-flux (GER) to ELMT and the diagnosis of MMD.

HypothesesNull hypothesis

Extrinsic laryngeal muscle tension (ELMT) pat-terns are the same in patients with muscle tensiondysphonia (MMD) and non-MMD patients. There isno difference in extrinsic laryngeal muscle tension(ELMT) patterns in patients with and without gas-troesophageal reflux.

Alternative hypothesisExtrinsic laryngeal muscle tension (ELMT) pat-

terns are not the same in patients with muscle tensiondysphonia (MMD) and non-MMD patients. Extrinsiclaryngeal muscle tension (ELMT) patterns are differ-ent in patients with gastroesophageal reflux disorders(GER) than those without GER.

MATERIAL AND METHODS

The study was conducted in the Pacific Voice Clin-ic at the Vancouver General Hospital during a 1-yearperiod from January 1 to December 31, 1999. Allnew patients who fit inclusion-exclusion criteria(Figure 1) were included in the study. Voice evalua-tions began with an interview followed by vocalfunction evaluation, extrinsic laryngeal muscle ten-sion (ELMT) palpation, standard otolaryngologicalexamination, and videostrobolaryngoscopy. A grad-ing system for four separate muscle groups aroundthe larynx was established, based on the originalwork of Lieberman.3 Our severity scale is 0 to 3, with0 indicating normal tone, 1 for mild, 2 for moderate,and 3 for severe increase in palpable muscle tension.

Figure 2 describes the technique of palpation of thesuprahyoid (S), thyrohyoid (T), cricothyroid (C) andpharyngolaryngeal (P) muscle groups. Figure 3 liststhe criteria used to assign a tension severity grade to

334 THANA ANGSUWARANGSEE AND MURRAY MORRISON

Journal of Voice, Vol. 16, No. 3, 2002

each. The criteria for the diagnosis of muscle misusedysphonia (MMD) and gastroesophageal reflux(GER) are summarized in Figure 4. Patients withborderline clinical GER were further investigated by24-hour ambulatory pH monitoring test.

A double-blinded method was used to compare in-terrater differences in ELMT assessment. Fifty-sevenpatients in succession were evaluated by two oto-laryngologists (the authors) during a 30-day period.One examiner evaluated the patient in the clinic dur-ing the routine sequence, and the other before the pa-tient entered the clinic. Intrarater reliability waschecked by evaluation of EMLT before and after theclinic visit by the laryngologist not doing the routineassessment. All immediate adverse reactions to thepalpation were recorded. Delayed adverse reactionswere to be reported by phone.

We included only new patients in the study to pre-vent possible bias from knowing the previously as-signed diagnosis. The palpation of ELMT was done

after the history to avoid possible adverse effectssuch as laryngospasm, and before videolaryn-goscopy to avoid possible alteration of ELMT fromthat procedure. The diagnoses were made by consen-sus of voice clinic team members to avoid examinerdiagnostic bias from knowing the ELMT result.

Informed consentSince the palpation of ELMT is a safe procedure

and part of our routine clinical evaluation in the Pa-cific Voice Clinic, there is no need for informed con-sent from the patients. However, all patients were in-formed about the palpation before the examinationand were told to inform the examiner if they felt un-comfortable or wanted the palpation terminated.

Biostatistical analysis methods The relationship between ELMT palpation scores

and the diagnosis were analyzed as follows:

EXTRINSIC LARYNGEAL MUSCULAR TENSION 335


FIGURE 1. Patient selection criteria.

Inclusion Criteria

1. New with voice disorders patients

2. Age 12 years old or older

3. Male, female, and transgender

Exclusion Criteria

1. Airway-compromised patients

2. Extensive scarring of anterior cervical skin and soft tissue around the

larynx from any causes (e.g. surgery, radiation therapy, trauma)

3. Abnormal laryngeal framework from congenital or acquired causes (e.g.,

laryngeal trauma, laryngeal framework surgery)

4. History of laryngospasm, stridor, or airway compromise initiated by

manipulation of the larynx or adjacent structure

5. Tracheotomized or laryngectomized patients

6. Cervical pathology that precludes complete evaluation of ELMT by the

palpation techniques, e.g., mass lesion around the larynx

7. Neurological conditions that preclude proper ELMT palpation

examination e.g. abnormal cervical posture, uncontrollable spontaneous

head and neck movement, unable to vocalize as instructed

8. Patient is not cooperative or is under emotional distress

9. Short, fatty neck: unable to identify laryngeal landmarks

1. The Mann-Whitney U nonparametric test wasused to compare ELMT scores between MMDand non-MMD, and between GER and non-GER patients.

2. Logistic regression methods were used to iden-tify explanatory variables that significantly af-fected the following outcome variables:

• The diagnosis of muscle misuse dysphonia(MMD) or nonmuscle misuse dysphonia(non-MMD).

• The diagnosis of gastroesophageal reflux(GER) disorder or non-GER.

3. The Wilcoxon signed ranks nonparametric testwas used to compare ELMT scores between



FIGURE 2. Technique of palpation.

Suprahyoid muscles (S)

� Midline upward palpation in submental space with middle finger

Observe : 1. tension at rest

2. contraction during low-pitched /a/ follow by high-pitch /u/ phonation

Thyrohyoid muscles (T)

� Palpate both thyrohyoid spaces with the thumb and forefinger

Observe : 1. tension at rest

2. contraction during connected speech (count 1 to 5), and with an easy hum

Cricothyroid muscles (C)

� Feel the cricothyroid space in midline with tip of the index finger

Observe : 1. position of the cricoid arch relative to the thyroid cartilage

2. size of the space at rest

3. closing and opening of the space during high-ptiched and low-pitched

Pharyngo-laryngeal muscles (inferior constrictor) (P)

� Rotate the larynx, hook posterior edge of thyroid cartilage with index finger and

draw forward, feel the posterior aspect of the cricoid cartilage with middle and ring

finger

Observe : 1. tension in pharyngeal muscles

2. associated arytenoid movement and posterior cricoarytenoid (PCA) muscle

contraction during sniffing

Important note:

� Laryngeal palpation should be done before any intraoral or laryngoscopic

examination to avoid changes in muscle tension due to the manipulation.

� Some tenderness may be found in these muscle groups, and should be noted.

� Examination is best done from the side, with the head, neck, and shoulders

in a neutral position.

phonation



FIGURE 3. Criteria for extralaryngeal muscular tension grading system.

Suprahyoid muscles (S)

0 = soft at rest, may slightly contract on phonation

1 = soft at rest, mild low-pitch and moderate high-pitch contraction

2 = some tension at rest, tense with jaw protrusion on phonation

3 = tense all the time, maximally tight on phonation

Thyrohyoid muscles (T)

0 = no muscular contraction at rest, mild on phonation

1 = soft thyrohyoid space at rest, some contraction on phonation

2 = tense, narrow thyrohyoid space at rest, moderate contraction on phonation

3 = very tense with closed thyrohyoid space all the time

Cricothyroid muscles (C)

0 = normal cricothyroid space and phonatory movement

1 = narrowing of cricothyroid space at rest, some movement on phonation

2 = anterior displacement of cricoid cartilage with narrowing of cricothyroid space at

rest, closing of the space on phonation

3 = closed cricothyroid space all the time

Pharyngolaryngeal muscles (inferior constrictor) (P)

0 = soft, easy to rotate the larynx for 90° and palpate posterior cricoarytenoid

(PCA) muscle and arytenoid movement on sniffing

1 = slightly tense, cannot palpate PCA muscle movement on sniffing

2 = moderately tense, difficult to rotate the larynx but still can palpate the posterior

edge of thyroid cartilage

3 = very tense, cannot rotate the larynx at all

FIGURE 4. Diagnostic criteria.

Diagnostic criteria for MMD

� Absence of organic lesion or cause of dysphonia

� History of vocal misuse or abuse

� Demonstration of typical laryngoscopic pattern of MMD

Diagnostic criteria for GERD

� History of GERD symptom(s)

� Chronic inflammation of the posterior part of the larynx demonstrated by

videostrobolaryngoscopy

� Positive result of 24-hour pH monitoring test

examiners (interrater) and pre-examination andpostexamination scores (intrarater).

RESULTS

In 1999, 1135 patients visited the Pacific VoiceClinic and 499 of these were new patients. Four hun-dred sixty-five patients, 303 (65%) female and 162(35%) male, were included in the study. Transgenderpatients were assigned their birth gender for thisstudy. Age ranged from 13 to 98 years (mean = 44.8,median = 44, SD = 17.3). Primary diagnoses werecategorized into two main groups, muscle misusedysphonia (MMD) and nonmuscle misuse dysphonia(non-MMD). All 19 subcategories of both groups aresummarized in Table 1, including the number andpercentage of cases with GER. There were 175(37.6%) patients with a clinical diagnosis of GER. Ofthe 141 patients with the diagnosis of MMD, 70

(49.6%) of them had GER compared to 105 (32.4 %)of the non-MMD patients. Thirty-four patients wereexcluded according to the exclusion criteria andthese are summarized in Table 2.

STATISTICAL ANALYSES

Nonparametric testsThe Mann-Whitney U test was used to study the

relationship between muscle tension scores in thefour groups and the diagnosis groups (non-MMDand MMD) as well as the relationship to GER. Theresults shown in Table 3 indicate a strong relation-ship between thyrohyoid muscle tension, GER, andMMD (p ≤ 0.01). Subgroup analysis, separatingMMD into MMD3 and other MMD, and comparingthese to the non-MMD, showed that the thyrohyoidmuscle tension and GER were significantly differentonly between MMD3 and non-MMD.



TABLE 1. Primary Diagnosis Categories

Primary Diagnosis No. of Cases Percent No. of GER % of GER

Muscle misuse dysphonia 141 30.3 70 49.65Muscle misuse type 1 14 3.0 8 57.14Muscle misuse type 2 19 4.1 9 47.37Muscle misuse type 3 70 15.1 41 58.57Muscle misuse type 4 8 1.7 1 12.50Muscle misuse type 5 5 1.1 0 0.00Muscle misuse—nonspecific 25 5.4 11 44.00

Non-muscle misuse dysphonia 324 69.7 105 32.41Congenital sulcus and cyst 9 1.9 2 22.22Functional miscellaneous* 16 3.4 2 12.50Irritable larynx syndrome 40 8.6 22 55.00Chronic laryngitis and granuloma 53 11.4 36 67.92Laryngeal trauma 18 3.9 5 27.78Normal 13 2.8 3 23.08Organic miscellaneous† 16 3.4 1 6.25Vocal fold paralysis 35 7.5 9 25.71Spasmodic dysphonia 25 5.4 4 16.00Tumor 19 4.1 0 0.00Vocal nodule 37 8.0 14 37.84Vocal polyp 14 3.0 3 21.43Neurological disorders 29 6.2 4 13.79

Total 465 100.0 175 37.63

†Organic miscellaneousincludes subglottic stenosis and cricopharyngeal muscle spasm.

*Functional miscellaneous includes articulation disorders, temporomandibular joint disorder, senileatrophic bowing, and gender dysphoria.

Logistic regressionLogistic regression was used to identify the ex-

planatory variables of interest (ELMT scores) thatsignificantly affect the outcome variables of inter-

est (diagnosis of MMD and GER) while control-ling for age and sex. The analysis results of the sig-nificant variables in each model are summarized inTable 4.



TABLE 2. Excluded Cases

Exclusion Criteria Number of Cases

Airway-compromised patients 3

Neck scarring from surgery, radiation therapy, or trauma 5

Age less than 12 years old 1

History of laryngospasm, stridor, or airway compromise 3

Tracheotomized patients 2

Cervical pathology: mass lesion around the larynx 1

Neurological conditions that preclude ELMT assessment 8

Patients who were not cooperative or who were under emotional distress 10

Short, fatty neck: unable to identify laryngeal landmarks 1

Total 34

TABLE 3. Nonparametric Tests (Test Statistics: Mann-Whitney U Test)

Comparing Test Groups (n) statistics Age Sex Suprahyoid Thyrohyoid Cricothyroid Pharyngolaryngeus GERD

Non-MM (324) Z -4.421 -5.525 -1.026 -4.708 -2.808 -2.118 -3.523vsMM (141) Asymp. Sig. 0.000* 0.000* 0.305 0.000* 0.005* 0.034* 0.000*

(two-tailed)

Non-MM (324) Z -4.035 -4.243 -.054 -5.901 -2.172 -2.276 -4.105vsMM3 (70) Asymp. Sig. 0.000* 0.000* 0.957 0.000* 0.030* 0.023* 0.000*

(two-tailed)

Non-MM (324) Z -2.757 -4.078 -1.515 -1.338 -2.126 -.984 -1.358VsOther-MM (71) Asymp. Sig. 0.006* 0.000* 0.130 0.181 0.034* 0.325 0.174

(two-tailed)

Other-MM (71) Z -.897 -.190 -1.124 -3.927 -.009 -1.007 -2.097vsMM3 (70) Asymp. Sig. 0.370 0.849 0.261 0.000* 0.993 0.314 0.036*

(two-tailed)

GERD (290) Z -1.068 -3.204 -1.603 -2.928 -2.849 -1.897vs.non-GERD (175) Asymp. Sig. 0.286 0.001* 0.109* 0.003* 0.004* 0.058

(two-tailed)

*p < 0.05.

Abbreviations: Non-MM, non-muscle misuse dysphonia; MM, muscle misuse dysphonia; MM3, muscle misuse dysphonia type 3; oth-er-MM, muscle misuse dysphonia except MMD3; GERD, gastroesophageal reflux disorders; (n) = number of patients in the group

GER 24-hour pH monitoring resultOf 39 patients with borderline clinical GER sent for

24-hour pH monitoring, 35 underwent the test and 24(68.6 %) demonstrated significant pathological GER.Pearson correlation showed no significant correlationbetween any of the ELMT scores and DeMeester(GER standard test) scores. The ELMT scoresshowed no statistical difference between patients withpositive and negative 24-hour pH monitoring tests.Tables 5, 6, and 7 present EMLT and GER results.

Interrater reliabilityDouble-blinded evaluation of ELMT was performed

in 57 successive patients during a 30-day period. Theresults of paired sample Wilcoxon signed-ranks testshowed significant difference (p< 0.05) in the pharyn-golaryngeal muscle. There is no significant differencebetween examiners in other groups of ELMT scores.Table 6 presents data on interrater reliability.

Intrarater reliabilitySince the examiner still may remember the first pal-

pation scores while doing the second palpation it isprobably better to interpret this result as pre and postvideostrobolaryngoscopy ELMT changes, rather thanas intrarater reliability. The pharyngolaryngeal mus-cle tension is the only score that shows a statisticallysignificant difference between two examinations.Table 7 presents data on intrarater reliability.

Adverse reactionsNo immediate or delayed adverse effect from the

palpation was observed, recorded in the clinic, or re-ported by the patients during the study period. Mosttolerated the palpation without complaint.

DISCUSSION

Since Morrison et al coined the term muscle ten-sion dysphonia (MTD) in 1983,7 some changes have



TABLE 4. Logistic Regression Results

ModelLikelihood Ratio

Comparing Groups (degree freedom) Significant Explanatory Variables*

in the model(n) (Significance) Variables B Wald Sig. Exp (B)

Non-MM (324) 76.017 Age -0.0224 9.9672 0.0016 0.9779vs (7) Sex -1.2254 19.4819 0.0000 0.2937MM (141) (0.0000) T 0.6594 13.3284 0.0003 1.9337

GERD 0.5622 6.2020 0.0128 1.7545

Non-MM (324) 84.376 Age -0.0235 5.4247 0.0199 0.9768vs (7) Sex -1.3910 12.0651 0.0005 0.2488MM3 (70) (0.0000) T 1.4680 26.5443 0.0000 4.3403

GERD 0.8964 8.4386 0.0037 2.4508

Non-MM (324) 28.345 Age -0.0217 6.3150 0.0120 0.9785vs (7) Sex -1.1106 9.8908 0.0017 0.3293Other-MM (71) (0.0002)

Other-MM (71) 30.891 S -0.5253 5.0259 0.0250 0.5914vs (7) T 1.5850 18.9107 0.0000 4.8759MM3 (70) (0.0001) GERD 0.7830 4.0790 0.0434 2.1880

GERD (290) 23.095 Age 0.0112 3.4038 0.0650 1.0112vs. (6) Sex -0.7283 10.4620 0.0012 0.4827non-GERD (175)` (0.0008)

*p < 0.05.

Abbreviations: Non-MM, non-muscle misuse dysphonia; MM, muscle misuse dysphonia; MM3, musclemisuse dysphonia type 3; other-MM, muscle misuse dysphonia except MM3; S, Suprahyoid; T, Thyrohy-oid; GERD, gastroesophageal reflux disorders; (n), number of patients in the group; classification cut-offvalue = 0.5; B, estimated logit coefficient; Wald = [B/S.E.]2; Sig., significant level of the coefficient; Exp(B), “odds ratio” of the individual coefficient.

been made to refine the classification. In 1993, wemade a major change and began to use the termmus-cle misuse dysphonia(MMD) instead of MTD.2 Weclassified these nonorganic voice disorders into mus-cle misuse types 1–6 according to different laryngo-scopic laryngeal postures. After using this new classi-fication for some time, we found that there were somepatients with muscle misuse disorders that did not fitwell into any category so their disorder was termednonspecific muscle misuse. We also observed that ex-tralaryngeal muscle tension was more prominent in

people with some types of muscle misuse dysphoniathan in patients with other voice disorder diagnoses.

A diagnosis of muscle misuse voice disorder im-plies abnormal laryngeal posture, which may resultfrom a variety of causes. For example, hyperlordosisof the cervical spine with an extended head andkyphotic hump in the upper thoracic vertebrae cancause poor laryngeal posture, increased vocal effort,and muscular tension in and around the larynx duringphonation.8 If not corrected, habitual misuse of la-ryngeal muscles during phonation may slowly



TABLE 5. EMLT and GER

Test statistics Age Sex Suprahyoid Thyrohyoid Cricothyroid Pharyngolaryngeus

Mann-Whitney U 117.5 98.50 88.000 104.500 130.500 92.500

Wilcoxon W 417.5 398.50 154.000 170.500 196.500 158.500

Z -0.515 -1.422 -1.634 -1.040 -0.057 -1.470

Asymp. Sig. 0.606 0.155 0.102 0.298 0.955 0.142(two-tailed)

Exact Sig. 0.612 0.238 0.123 0.334 0.958 0.163[2*(one-tailed Sig.)]

Grouping: Reflux vs nonreflux defined by 24-hour pH monitoring. There was no significant difference between the groups.

TABLE 7. Intrarater Reliability(Wilcoxon Signed-Ranks Test)

S3 - S2 T3 - T2 C3 - C2 P3 - P2

Z -0.333A 0.000B -1.000C -2.333c

Asymp. Sig. (two-tailed) 0.739 1.000 0.317 0.020

ABased on positive ranks.

BThe sum of negative ranks equals the sum of positive ranks.

CBased on negative ranks.

TABLE 6. Interrater Reliability(Test Statistics Wilcoxon Signed-Ranks Test)

S2 - S1 T2 - T1 C2 - C1 P2 - P1

Z -0.921* -0.349† -0.474† -2.232†

Asymp. Sig. (two-tailed) 0.357 0.727 0.636 0.026

*Based on positive ranks.

†Based on negative ranks.

S1,T1,C1,P1 = main examiner’s scores. S2,T2,C2,P2 = preclinical evalua-tion examiner’s scores

change the resting tone of laryngeal muscles so thatthey are persistently tense. In time, this may lead todistortion of the laryngeal skeletal complex and per-sistent closure of thyrohyoid or cricothyroid spaces,or anterior displacement of the cricoid cartilage rela-tive to the thyroid cartilage.9 Vocal fold lesions suchas vocal nodules, polyps, or sulcus vocalis may pro-mote secondary laryngeal muscle misuse, makingthe voice sound worse than would be expected fromthe appearance of the lesion.

Each of the four muscle groups evaluated in thisstudy plays a specific role in determining externaland internal laryngeal posture, at rest and duringphonation. In our experience, high tension in thesuprahyoid muscles, usually found in untrained per-formers, results in excessive elevation of the larynx.Contraction of the thyrohyoid muscles pulls the hy-oid bone and thyroid cartilage together and, in severecases, closes the thyrohyoid space. This consequent-ly produces anteroposterior supraglottic contraction,a typical laryngoscopic posture found in muscle mis-use dysphonia type 3 (MMD3). The cricothyroidmuscles increase pitch by lengthening the vocal cord,and also help to stabilize the cricoid-thyroid archi-tecture against the opposing pull of the thyroary-tenoid muscles.9 Therefore tension in cricothyroidmuscles will increase with thyroarytenoid muscletension. If the tension persists for long enough, theoblique belly of the cricothyroid muscles may fatigueand relax, resulting in subluxation of the cricothyroidjoints and palpable anterior displacement of thecricoid cartilage.

As noted above, our study showed that, after con-trolling for age and sex, there is a strong relationshipbetween thyrohyoid muscle tension, GER, andMMD (p ≤ 0.01). But subgroup analysis showed thatthe thyrohyoid muscle tension and GER were signif-icantly different only between MMD3 and non-MMD patients. Muscle misuse dysphonia type 3 in-volves inappropriate anteroposterior contraction ofthe supraglottic larynx during voicing. The arytenoidarea and epiglottis may be drawn almost together inthis form of abnormal laryngeal posture. From ananatomical point of view, it makes sense that excesscontraction of the thyrohyoid muscles and closure ofthe space between the hyoid bone and the thyroidcartilage would enhance this posture. The relation-ship of GER to MMD3 might imply a causal rela-

tionship between them. The unique anteroposteriorcontraction observed in MMD3 might be a protectivemechanism to shield the airway from acid reflux.From this point of view, longstanding GER might bethe cause of MMD3, or in other words MMD3 mightbe one of the laryngeal manifestations of reflux.

Gastroesophageal reflux (GER) is commonly asso-ciated with voice disorders. When gastric acid regur-gitates through the esophagus into the laryngophar-ynx, airway protective mechanisms are triggered thatresult in closure of the glottis, increased salivationand swallowing, coughing or choking, and tighteningof laryngopharyngeal constrictor muscles, especiallythe cricopharyngeus. Our previous porcine animalstudy demonstrated a direct reflex relationship be-tween stimulation of the lower esophagus and thy-roarytenoid muscle activity.6 Voice patients with re-flux may have symptoms ranging from minor throatirritation, globus pharyngeus, frequent throat clear-ing, heartburn, chronic cough, morning hoarseness orsore throat, nocturnal choking, or episodic laryn-gospasm. Interestingly, comparison of reflux andnonreflux groups in the logistic model did not showa statistically significant difference in tension in anyof the muscle groups (p > 0.05). A potential source oferror is that not all patients had pH testing. Patientsthat seemed to have obvious laryngopharyngeal re-flux by history and examination frequently did notundergo pH testing, but were treated empirically.Thus the patients studied might have been those inwhom the diagnosis of reflux was equivical.

While there was no interrater difference in tensionratings for the suprahyoid, thyrohyoid, and cricothy-roid groups, the significant difference between ex-aminers in the pharyngolaryngeal palpation scoresmight be the result of difficulty in this muscle palpa-tion technique. It requires rotation of the larynx tofeel the movement of the arytenoid cartilage or con-traction of the posterior cricoarytenoid muscles. Toaccurately perform this palpation requires more prac-tical experience than the other three muscle groups,which do not require manipulation of the larynx.

Since the time between the two examinations isquite short, i.e., less than 1 hour, the intrarater relia-bility might not be valid due to examiner bias. The re-sult of this comparison might better be interpreted asELMT change after videostrobolaryngoscopy. Onlythe pharyngolaryngeal muscle tension showed signif-icant change after the videostrobolaryngoscopy.



In our experience, there are no adverse effects oflaryngeal palpation performed by qualified practi-tioners. Except for the pharyngolaryngeal palpation,our technique and scoring criteria are simple, andeasy to learn. It provides another clinical tool for as-sessment of patients with voice disorders. In additionto helping the clinician form a diagnostic profile foreach patient, the palpation skills naturally extend tolaryngeal manipulation as an adjuvant to voice thera-py. In some patients, the palpation of suprahyoid andthyrohyoid muscles can be used as biofeedback or asa self-monitoring tool during and after voice therapy.The disadvantages of this diagnostic tool are the sub-jective nature of the method and the limited ability topalpate some patients, such as those with a short fat-ty neck, previous trauma, surgery, or radiation.

CONCLUSION

This study showed that, based on our extrinsic la-ryngeal muscle tension (ELMT) palpation and grad-ing criteria, thyrohyoid tension is the only musclegroup that demonstrated a statistically significant re-lationship with muscle misuse dysphonia (MMD),specifically MMD type 3. No significant difference inthe ELMT scores was found between GER and non-GER patients although it is postulated that a causal re-lationship was found between MMD3 and GER.

Palpation of extrinsic laryngeal muscles can yieldinformation about laryngeal posture at rest and dur-ing phonation. Integration of this examination tech-nique into routine laryngeal examinations, particular-ly in patients with voice disorders, can help theclinician make a more accurate diagnosis and planappropriate management.

The palpation technique and grading system crite-ria used in our clinic are easy to use with good inter-

rater reliability except for the pharyngolaryngealmuscle tension. The technique used to palpate thismuscle group is more difficult than that of other mus-cle groups and might stimulate the muscle to increasetension after the first examination. Like other physi-cal examinations, practice and experience, plus theuse of standard criteria, can increase reliabilityamong examiners. We encourage clinicians to addthis palpation technique to their routine clinical prac-tice, as further information gained through practice iscrucial to refining and standardizing the palpationtechnique as a useful clinical tool.

REFERENCES

1. Harris T, Harris S, Rubin JS, Howard DM. The Voice ClinicHandbook.London: Whurr; 1998: Preface xvi–xvii.

2. Morrison MD, Rammage LA. Muscle misuse voice disor-ders: description and classification. Acta Otolaryngol1993;113:428–434.

3. Lieberman J. Principles and techniques of manual therapy:applications in the management of dysphonia. In: Harris T,Harris S, Rubin JS, Howard DM, eds. The Voice Clinic Hand-book.London: Whurr; 1998: 91–138.

4. Vilkman E, Sonninen A, Hurme P, Korkko P. External laryn-geal frame function in voice production revisited: a review. JVoice.1996;10:78–92.

6. Gill C, Morrison MD. Esophagolaryngeal reflex in a porcineanimal model. J Otolaryng.1997; 27:76–80.

5. Koufman JA. The otolaryngologic manifestations of gastro-esophageal reflux disease (GERD). Laryngoscope.1991;101(supp53):1–78.

7. Morrison MD, Rammage LA, Belisle G, Nichol H, Pullan B.Muscular tension dysphonia.J Otolaryngol. 1983;12:302–306.

8. Morrison MD, Rammage LA, Nichol H. Management of theVoice and Its Disorders.2nd ed. San Diego, Calif: Singular,2001:28–35.

9. Harris T, Lieberman J. The cricothyroid mechanism, its rela-tion to vocal fatigue and vocal dysfunction.Voice Forum.1993;2:89–96.



Documents

(Morrison) Tension Muscular Laringea Extrinsica