Functional dysphonia Nelson Roy, PhD, CCC-SLP Functional dysphonia-a voice disturbance in the absence of structural or neurologic laryngeal pathology-is an enigmatic and controversial voice disorder that is frequently encountered in multidisciplinary voice clinics. Poorly regulated activity of the intrinsic and extrinsic laryngeal muscles is cited as the proximal cause of functional dysphonia, but the origin of this dyregulated laryngeal muscle activity' has not been fully elucidated. Several causes have been cited as contributing to this imbalanced muscle tension; however, recent research evidence points to specific personality traits as important contributors to its development and maintenance. Voice therapy by an experienced speech-language pathologist remains an effective short-term treatment for functional dysphonia in the majority of cases, but less is known regarding the long-term fate of such intervention. Further research is needed to better understand the pathogenesis of functional dysphonia, and factors contributing to its successful management. Curr Opin Otolaryngol Head Neck Surg 2003, 11: 144-148 © 2003 Lippincott Williams & Wilkins, Department of Communication Sciences & Disorders & Division of Otolaryngology-Head & Neck Surgery, The University of Utah, Salt Lake City, Utah, USA Correspondence to Nelson Roy, PhD, Department of Communication Sciences & Disorders, The University of Utah, 390 South, 1530 East, Room 1219, Salt Lake City, UT 84112, USA; e-mail: nelson.roy@health,utah.edu Current Opinion in Otolaryngology & Head and Neck Surgery 2003, 11 :144-148 Abbreviations FD functional dysphonia ISSN 1068-9508 © 2003 Lippincott Williams & Wilkins Functional dysphonia (FD) refers to a voice disturbance that occurs in the absence of structural or neurologic laryngeal pathological characteristics, and may account for 10 to 40% of cases referred to multidisciplinary voice clinics [1-3]. FD occurs predominantly in women, com monly follows upper respiratory infection symptoms, is frequently transient, and varies in its response to treat ment [1,4,5J. Functional dysphonia and aphonia are of ten regarded as disorders on a continuum of severity, and are believed by some to share a common cause. In apho nia, patients speak in a whisper, whereas dysphonia im plies phonation is preserved, but disordered in quality, pitch, or loudness [6-8]. The term "functional" implies a voice problem of physi ological function rather than anatomic structure [9-]. In clinical circles, "functional" is usually contrasted with "organic" and often carries the added meaning of psy chogenic [10J. Stress, emotion, and psychologic conflict are frequently presumed to cause or exacerbate func tional symptoms. Some confusion surrounds the diagnos tic category of "functional dysphonia," because it in cludes an assortment of medically unexplained voice disorders: psychogenic, conversion, hysterical, tension fatigue syndrome, hyperfunctional, muscle misuse, or muscle tension dysphonia [11-15]. Although each diag nostic label implies some degree of etiologic heteroge neity, whether these disorders are qualitatively different and etiologically distinct remains unclear. When applied clinically, these various diagnostic labels often reflect cli nician supposition, bias, or preference. However, at the purely phenomenological level, there may be few em pirically tractable differences that reliably distinguish these voice disorders. More recently, "muscle tension dysphonia" has become the preferred diagnostic label to describe functional voice problems presumably related to dysregulated or imbalanced laryngeal and paralaryngeal muscle activity [12,16,17J. A variety of glottic and supraglottic contrac tion patterns have been associated with muscle tension dysphonia/FD, and several classification systems have been offered to describe these laryngoscopic features [16,18,19J. Often-cited laryngeal manifestations of dys regulated laryngeal muscle tension include the follow ing: tight mediolateral glottic and/or supraglottic contrac tion, anteroposterior glottic and/or supraglottic compression, incomplete glottic closure, posterior glottic chink, and bowing [15,16,19]. However, researchers have recently challenged the existence of specific Iaryngo 144 Functional dysphonia Roy 145 scopic clusters/features that uniquely and reliably distin guish FD from nondysphonic speakers, and other voice disorder types including spasmodic dysphonia [9,20-,21]. Many of the laryngoscopic patterns used to classify FD are frequently observed in individuals with normal voices and spasmodic dysphonia, and thus fail to distin guish such individuals from patients with FD [9,21]. Given the likely involvement of a variety of intrinsic and extrinsic laryngeal muscles-in diverse states of relax ation and contraction-myriad laryngeal configurations may be present in FD [22]. Although poorly regulated activity of the intrinsic and extrinsic laryngeal muscles is cited as the proximal cause of muscle tension dysphonia, the origin of this muscle activity has not been fully elucidated. It has been attrib uted to a variety of sources, including (1) technical mis uses of the vocal mechanism in the context of extraordi nary voice demands [11-13,15], (2) learned adaptations after upper respiratory tract infection [14,23], (3) in creased pharyngolaryngeal tone secondary to the laryn gopharyngeal reflux reflex [18], (4) extreme compensa tion for minor glottic insufficiency and/or underlying mucosal disease [24], and (5) psychologic and/or person ality factors that tend to induce elevated tension in the laryngeal region [7,25-28-]. Psychologic factors in functional dysphonia A wide array of psychopathologic processes contributing to voice symptom formation in FD has been proposed [27,29]. The exquisite sensitivity and prolonged hyper contraction of the intrinsic and extrinsic laryngeal muscles, in response to stress, conflict, anxiety, depres sion, or inhibited emotional expression, is frequently cited as the common denominator underlying the major ity of functional voice problems [7,30]. Other possible mechanisms include, but are not limited to, conversion reaction, hysteria, hypochondriasis, and various situ ational conflicts or personality dispositions that also in duce excess or dysregulated laryngeal musculoskeletal tension [6,25,26,28]. However, research evidence to sup port these various psychologic mechanisms has seldom been provided. The empirical literature evaluating the FD-psychology relationship is characterized by diver gent results regarding the frequency and degree of spe cific personality traits [6,31-34",35"], conversion reac tion [6,36], and psychopathologic symptoms such as depression and anxiety [6,31,34-,35-40]. Despite signifi cant methodologic differences among these studies, some interesting patterns do surface. These patterns suggest a general trend tmvard elevated levels of (1) state and trait anxiety, (2) depression, (3) somatic preoccu pation/complaints, and (4) introversion in the FD popu lation. Patients have been described as inhibited, stress reactive, socially anxious, and nonassertive, with a ten dency toward restraint [31,33,34,35",36]. The inter- ested reader is referred to Roy and Bless [28-] for a more complete exploration of the putative psychologic and personality processes involved in FD, as well as related research. Recently, a theory has been proposed to link specific personality traits to the development of FD [28-,41-]. The "Trait theory of FD" emphasized a theme of in hibitory laryngeal behavior, but attributed this muscu larly inhibited voice production to specific personality typologies. In brief, the authors speculated that the com bination of personality traits, such as introversion and neuroticism (trait anxiety), contributes to predictable and conditioned laryngeal inhibitory responses to certain environmental signals/cues. For instance, when undesir able punishing or frustrating outcomes have been paired with previous attempts to speak out, Roy and Bless pos tulated that this might lead to muscularly inhibited voice production in individuals predisposed by specific person ality characteristics. The authors contended that this conflict between laryngeal inhibition and activation (that has its origins in personality and nervous system func tioning), results in elevated laryngeal tension states and can give rise to incomplete or disordered vocalization in a structurally and neurologically intact larynx. In research designed to test the theory and assess wheth er personality factors play causal, concomitant, or conse quential roles in common voice disorders, Roy and col leagues [34",35"] compared a vocally normal control group and four groups with voice disorders-FD, vocal nodules, spasmodic dysphonia, and unilateral vocal fold paralysis-using The Eysenck Personality Question naire. The Eysenck Personality Questionnaire-a popu lar personality assessment tool-generates scores for the personality superfactors: extraversion and neuroticism. Extraversion involves the willingness to engage and con front the environment, including the social environment. Extraverts (high extraversion) tend to be dominant, so ciable, and active, whereas introverts (low extraversion) tend to be quiet, unsociable, passive, and careful. Neu roticism, the second personality dimension, can be lik ened to emotionality and is related to anxious, de pressed, tense, and emotional characteristics. High neuroticism individuals tend to be emotionally unstable, worried, and highly reactive to environmental stimuli [34"]. The results showed that distinct personali ty char acteristics were present \vithin the FD and vocal nodules groups, and were conspicuously absent in the other groups. Group comparisons revealed that the majority of FD and vocal nodules subjects were classified as intro verts and extraverts, respectively. As compared to the other groups, the FD group scored significantly higher on the neuroticism dimension, thereby providing robust evidence to support the role of elevated neuroticism in FD development. Comparisons involving the spasmodic dysphonia, unilateral vocal fold paralysis, and control ----------------_. 146 Speech therapy and rehabilitation subjects did not identify any consistent personality dif ferences. On the whole, these differences in personality were compatible with the predictions of the Trait Theory of the dispositional bases of FD. In contrast, the disability hypothesis, which suggests that personality features and emotional maladjustment are solely a nega tive consequence of vocal disability, was not supported. The investigators concluded that the results largely sup port the contention that individuals with certain person ality traits may be susceptible to developing FD [34",35"]. Management of functional dysphonia Despite considerable controversy surrounding causal mechanisms, the clinical voice literature is replete with evidence that symptomatic voice therapy for functional voice disorders can often result in rapid and dramatic voice improvement [4,7,10,15,21,42-46-,47-50]. Because excess or dysregulatedlaryngeal muscle tension is frequently offered as the cause of FD, many voice therapies including yawn-sigh, resonant voice therapy, visual and electromyographic biofeedback, progressive relaxation, and circumlaryngeal massage aim to reduce or rebalance such tension [7,48]. Prolonged hypercontrac tion of laryngeal muscles is often associated with eleva tion of the larynx and hyoid bone, with associated pain and discomfort when the circumlaryngeal region is pal pated [5,22,51]. Several voice clinicians have described manual/digital techniques to determine the presence and degree of laryngeal musculoskeletal tension, as well as methods to relieve such tension during the diagnostic assessment and management session [7,22,51-53]. Aron son [7] speculated that therapy failure for muscle tension voice disorders may be caused, at least in part, by tech niques that do not yield sufficient laryngeal tension re duction. He offered that indirect (ie, nonmanual) tension reduction techniques often fail because of the stubborn nature of excess larvngeal musculoskeletal tension. In stead, Aronson offered circumlaryngeal massage as a di rect method to induce laryngeal tension reduction. Skill fully applied, systematic kneading of the extralaryngeal region is believed to stretch muscle tissue and fascia, promote local circulation with removal of metabolic wastes, relax tense muscles, and relieve pain and discom fort associated with muscle spasms [22]. In a series of investigations, Roy and colleagues have evaluated the clinical utility of manual techniques with a variety of functional voice disorders [4,5,17,24]. Roy {'f al. [5] reported the immediate and long-term effects of manual circumlaryngeal therapy for 25 female patients with FD. Perceptual, acoustic, and interview techniques were used to assess vocal function before and after treat ment. Subjects demonstrated consistent improvement across perceptual and acoustic indices of vocal function immediately after treatment and during the follow-up period. Based on perceptual ratings, 96% of patients were rated as improved, with almost two thirds of all patients achieving normal voice return after the single treatment session. The hypothesized physical effect of such circumlaryn geal massage is reduced laryngeal height and stiffness and increased mobility. Once the larynx is "re leased/lowered" and range of motion is normalized, an improvement in vocal effort, quality, and dynamic range should follow. Roy and Ferguson [46-] combined knowl edge of the source-filter theory of vowel production with formant frequency analysis to indirectly assess changes in vocal tract length after successful manual circumlaryn geal therapy with 75 subjects with FD. The "length rule" of the source-filter theorv states that the average frequencies of the vowel formants (local resonances in the vocal tract) are inversely proportional to the length of the pharyngeal-oral tract. In short, as the vocal tract in creases in length, the average formant frequencies lower. Therefore, laryngeal elevation should shorten the verti cal dimension of the pharynx, whereas lowering of the larynx should result in lengthening of the pharyngeal oral tract. Therefore, a shorter vocal tract creates el evated formant frequencies; alternatively, a longer tract produces lmver formants. These investigators reported significant lowering of the first three formant frequencies of the vowel /a/ after voice improvement. These findings were compatible with a decrease in laryngeal height and lengthening of the vocal tract as predicted by the source filter theory, and provide corroborating evidence for Aronson's [7] contention that voice improvement after manual circumlaryngeal therapy for FD may be associ ated with lowered laryngeal position. Certainly, direct symptomatic therapy for FD can pro duce rapid voice changes; however, in some cases, voice therapy can be a frustrating and protracted experience for both clinician and patient [1,53,54]. Because there are few studies directly comparing the effectiveness of spe cific therapy techniques, not much is known about whether one therapy approach for FD is superior to an other. According to most sources, signs of voice improve ment should typically be observed within the first voice therapy session; however some patients may require an extended, intensive treatment session or several ses sions, depending on a number of variables including the therapy technique(s) selected, clinician experience and confidence in administering the approach, and patient motivation and tolerance. In cases of FD that are unre sponsive or resistant to standard voice therapy, Dworkin et al. [55-] recently reported the use of transcricothyroid membrane lidocaine injection to successfully interrupt hyperactive glottal and supraglottal muscle contraction patterns observed in three patients with refractory muscle tension dysphonia/FD. When the lidocaine in jection was followed by several minutes of voice therapy, Functional dysphonia Roy 147 all three previously unresponsive patients experienced prompt and sustained voice improvement. The exact mechanism underlying the positive result remains uncer tain; however, the authors h'ypothesize that the topical lidocaine bath acts on the mucosal mechanoreceptors of the laryngeal inlet, interrupting sensorv feedback during phonation, and breaking the cycle of hyperfunctional vo cal fold contraction that contributes to the dysphonia. Whether this procedure is best administered after tradi tional voice therapy has failed, or before voice therapy is offered, requires further investigation. The long-term effectiveness of direct voice therapy for functional voice disorders also has not been rigorously evaluated [48,49]. Of the few investigations that exist, the results regarding the durability of voice improvement after direct therapy for FD are mixed [5,10,42,44]. It should be acknowledged that after direct voice therapy, only the voice symptom has been removed, not the un derlying cause of the disturbance itself [26,32,37]. Therefore, the nature of precipitating and perpetuating factors, including possible psychologic dysfunction, needs to be better understood. If the situational, emo tional, or personality features that contributed to the de velopment of the voice disorder remain unchanged after behavioral treatment, it would be logical to expect that such persistent factors would increase the probabil ity/risk of future recurrences [35",42,56]. Therefore, in some cases, posttreatment referral to a psychiatrist or psychologist may be necessary to achieve more enduring improvements in the patient's emotional/life adjustment and voice function [26,54,56]. This is especially appro priate in cases where dysphonic relapses are frequent and protracted. References and recommended reading Papers of particular interest, published with the annual period of review. have been highlighted as: Of special interest Of outstanding interest Bridger MM, Epstein R: Functional voice disorders: a review of 109 patients. J Laryngol Otol 1983.97:1145-1148. 2 Koufman JA, Blalock PO: Functional voice disorders. Otolaryngol Clin North Am 1991,4:1059-1073. 3 Schalen L. Andersson K: Differential diagnosis and treatment of psychogenic voice disorder. Clin Otolaryngol 1992, 17:225-230. 4 Roy N, Leeper HA: Effects of the manual laryngeal musculoskeletal tension reduction technique as a treatment for functional voice disorders: perceptual and acoustic measures. J Voice 1993, 7:242-249. 5 Roy N, Bless OM, Heisey 0, et al.: Manual circum laryngeal therapy for func tional dysphonia: an evaluation of short- and long-term treatment outcomes. J Voice 1997, 11 :321-331. 6 Aronson AE, Peterson HW, Litin EM: Psychiatric symptomatology in func tional dysphonia and aphonia. J Speech Hear Dis 1966,31 :115-127. 7 Aronson AE: Clinical Voice Disorders: An Interdisciplinary Approach, edn 3. New York: Thieme, 1990. 8 Boone DR, McFarlane SC: The Voice and Voice Therapy, edn 6. Englewood Cliffs, NJ: Prentice Hall, 2000. 9 Sama A, Carding PN, Price S, et al.: The clinical features of functional dys phonia. Laryngoscope 2001. 111 :458-463. This well-designed research article questions the clinical utility and validity of laryn goscopic classification systems of FD. The laryngoscopic features commonly as sociated with FD are frequently prevalent in nondysphonic controls and fail to dis tinguish subjects with FD from normal subjects. 10 Carding P, Horsley I, Docherty G: A study of the effectiveness of voice therapy in the treatment of 45 patients with non organic dysphonia. J Voice 1999,13:72-104. 11 Morrison MD, Nichol H, Rammage LA: Diagnostic criteria in functional dys phonia. Laryngoscope 1986, 94:1-8. 12 Morrison MD, Rammage LA, Gilles MB, et al.: Muscular tension dysphonia. J Otolaryngol 1983, 12:302-306. 13 Morrison MD, Rammage L: Muscle misuse voice disorders: description and classification. Acta Otolaryngol (Stockh) 1993, 113:428-434. 14 Koufman JA, Blalock PO: Classification and approach to patients with func tional voice disorders. Ann Otol Rhinol Laryngol1982, 91 :372-377. 15 Koufman JA, Blalock PO: Vocal fatigue and dysphonia in the professional voice user: Bogart-Bacall syndrome. Laryngoscope 1988, 98:493-499. 16 Morrison MD, Rammage LA: The Management of Voice Disorders. San Diego: Singular Publishing Group, 1994. Conclusions Functional dysphonia-a VOIce disturbance in the ab sence of structural or neurologic laryngeal pathological factors-is an enigmatic and controversial voice disorder that is frequently encountered in multidisciplinary voice clinics. Recently, the term FD has been replaced in some clinical circles by the diagnostic label "muscle ten sion dysphonia," which serves to highlight excess, dvs regulated, or imbalanced activity of the intrinsic and ex trinsic laryngeal muscles as the proximal cause of the observed dysphonia. Although many sources have been cited as contributing to this muscle tension, specific per sonality traits have been identified as important to its development and maintenance. Voice therapy by an ex perienced speech-language pathologist remains an efIec tive short-term treatment for FD in the majority of cases, but little is known regarding the long-term fate of such treatment. Further research is needed to better under stand the pathogenesis of FD, and factors contributing to its successful management. 17 Roy N, Ford CN, Bless OM: Muscle tension dysphonia and spasmodic dys phonia: the role of manual laryngeal tension reduction in diagnosis and treat ment. Ann Otol Rhinol Laryngol1996, 105:851-856. 18 Morrison MO: Pattern recognition in muscle misuse voice disorders: how I do it. J Voice 1997, 11:108-114. 19 Lawrence VL: Suggested criteria for fibre-optic diagnosis of vocal hyperfunc tion. In Care of the Professional Voice Symposium. London: The British Voice Association; 1987. 20 Schneider B, Wendler J, Seidner W: The relevance of stroboscopy in func tional dysphonias. Folia Phoniatr Logop 2002,54:44-54. These researchers failed to find stroboscopic evidence (correlates) of subtypes of FD (ie, hyperfunctional vs. hypofunctional), nor did they identify any separate laryn gostroboscopic clusters to warrant subtyping of FD. 21 Leonard R, Kendall R: Differentiation of spasmodic and psychogenic dyspho nlas with phonoscopic evaluation. Laryngoscope 1999, 109:295-300. 22 Roy N, Bless OM: Manual circum laryngeal techniques in the assessment and treatment of voice disorders. Curr Opin Otolaryngol Head Neck Surg 1998, 6:151-155. 23 Milutinovic Z: Inflammatory changes as a risk factor in the development of phononeurosis. Folia Phoniatr 1991,43:177-180. 24 Roy N: Ventricular dysphonia following long-term endotracheal intubation: a case study. 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Roy N, Bless OM, Heisey 0: Personality and voice disorders: a superfactor trait analysis. J Speech Lang Hear Res 2000, 43:749-768. Personality superfactors and emotional adjustment are compared across a number of voice disorders and a non-voice-disordered control in this well·controlled study. The results are discussed within the context of the Trait theory of FD. 48 Ramig La, Verdolini K: Treatment efficacy: voice disorders. J Speech Lang Hear Res 1998, 41 :S1 01-S11 6. 49 Pannbacker M: Voice treatment techniques: a review and recommendations for outcome studies. Am J Speech Lang Pathol 1998, 7:49-64. 34 35 Roy N, Bless OM, Heisey 0: Personality and voice disorders: a multitrait multidisorder analysis. J Voice 2000, 14:521-548. The investigators compared personality factors in the identical groups as in the previous article [34], but used a personality test that permitted a more precise analysis of personality traits. The results revealed important differences in person ality traits between the FD and vocal nodules group, which were obscured at the superfactor trait level of analysis. 36 Roy N, McGrory JJ, Tasko SM, et al: Psychological correlates of functional dysphonia: an evaluation using the Minnesota Multiphasic Personality Inven tory. J Voice 1997, 11 :443-451. 37 Deary IJ, Scott S, Wilson 1M, et al.: Personality and psychological distress in dysphonia. Br J Health Psychol 1998, 2:333-341. 38 Pfau EM: Psychological factors underlying the etiology of psychogenic dys phonia. Folia Phoniatr 1975, 25:298-306. 39 White A, Deary IJ, Wilson JA: Psychiatric disturbance and personality traits in dysphonic patients. Eur J Dis Commun 1997, 32:121-128. 40 Friedl W, Friedrich G, Egger J, et al.: Psychogenic aspects of functional dys phonia. Folia Phoniatr 1993, 45:10-13. Roy N, Ferguson NA: Formant frequency changes following manual circum laryngeal therapy for functional dysphonia: evidence of laryngeal lowering? J Med Speech Lang Pathol 2001,9:169-175. These investigators used acoustic theory and analysis to assess the "laryngeal lowering hypothesis" to explain voice improvement in FD after successful manual circumlaryngeal therapy. Results from formant frequency analysis provided indirect support for Aronson's contention that the larynx lowers after circumlaryngeal mas sage. 50 Lieberman J: Principles and techniques of manual therapy: application in the management of dysphonia. In The Voice Clinical Handbook. Edited by Harris T, Harris S, Rubin JS.London, England: Whurr Publishers; 1998:91-138. 51 Rubin JS, Lieberman J, Harris TM: Laryngeal manipulation. Otolaryngol Clin North Am 2000, 33:1017-1034. 52 Peifang C: Massage for the treatment of voice ailments. 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