Annals of Oioliigy, Rhinohgy & Laryngology 116(1); 11-1 ©2007 Annals Publishing Company, All righis reserved. Transoral Approach to Laser Thyroarytenoid Myoneurectomy for Treatment of Adductor Spasmodic Dysphonia: Short-Term Results Chih-Ying Su. MD: Hui-Ching Chuang. MD; Shang-Shyue Tsai. PhD: Jeng-FenChiu,PhD Objectives: The surgical technique for the resection of the recurrent larvngeal nerve for adductor spasmodic dysphonia (ASD) ha.s high late failure rates. During the pa.st decade, botulinum toxin has emerged as the treatment of choice for ASD. Although effective, it also has significant disadvantages, including a temporary effect and an unpredictable dose- response relationship. In this study we investigated the effectiveness of a new transoral approach to laser thyroarytenoid mynneurectomy for treatment of ASD. Methods: Fourteen patients with ASD underwent transoral laser myoneurectomy of bilateral thyroarytenoid muscles. Under general anesthesia, an operating miLTOscope and a carbon dioxide laser were used to pertorm myectomy of the mid-posterior belly of bilateral thyroarytenoid muscles together with neurectomy ofthe terminal nerve fibers among the deep muscle bundles. Care was taken not to damage ihe vocal is ligaments, arytenoid cartilages, and lateral cricoarytenoid muscles. Preoperative and postoperative videolaryngostroboscopy and vocal assessments were studied, Results: The 13 patients who completed more than 6 months follow-up were enrolled in this study. Moderate and marked vocal improvement was achieved in 92^;? of the patient.s (12 of 13) after laser surgery during an average tbllow-up period of !7 months (range. 6 to 31 months). No vocaifoldatrophy or paralysis was observed in any patient. None of the patients had a recurrence during the foilow-up period. I Conclusions: Transoral laser myoneurectomy of bilateral thyroarytenoid muscles is a relatively simple, effective, and valuable technique for the treatment ot ASD. The durability ot outcome achieved with this procedure is encouraging. Key Words: adductor spasmodic dysphonia, recurrent laryngeal nerve, thyroarytenoid muscle, transoral laser myoneu- rectomy. ventricular fold hypertunction. INTRODUCTION ynx. However, its exact cause remains unknown. Spasmodic dysphonia most often presents as Adductor spasmodic dysphonia tends to be resis- the adductor type. Adductor spasmodic dysphonia tant to voice therapy. Surgical procedures that have (ASD) is a focal form of adult-onset taryngeal dys- been used to treat this disorder include recurrent tonia. and is related to excessive adduction or ad- laryngeal nerve section and type II thyroplasty.^'^ ductor spasm ofthe vocal folds.' It is characterized However, the.se procedures have the disadvantages by a strain-strangled voice pattern that is husky, of- of high late failure rates and a tendency to leave the ten with tretnors and involuntary pitch breaks in patient with a persistent breathy voice.-^-''Therefore, voicing. The voice quality often deteriorates further botulinum toxin (Botox) chemodenervation remains during stressful speaking situations. This can have a the standard of care for ASD in most tertiary spe- negative impact on the patient's quality of life and cialty centers.' Botox injection in the thyroarytenoid may lead to social isolation. As a type of dystonia. muscles provides substantial though variable relief spasmodic dysphonia has been considered a chron- of symptoms with few or no side effects. Howev- ic tieurologic disorder of central motor processing er, the vocal improvement lasts for a limited time, causing action-itiduced muscular spasms of the lar- from several v^'eeks to several months, and then the From the Department of Otolaryngology and the Voice Center. Chang Gung Memorial Hospital. Kaohsiung Medical Center. Chang Giing Universily College of Medicine (Su. Chuang). the Department of Health Care Adniinistralion. I-Shou Universily (Tsai). and [he Department of Medical Technology. Foo Yin Insiitnle of Technology (Chiu). Kaohsiung. Taiwan. Supported in part by grants from the National Science Council. Taiwan (NSC94-2314-B-182-05.1). and Chang Gung Memorial Hospital (NMRPDI40711). " Presented in part ai the XVIII IFOS World Congress. Rome. Italy. June 25-30. 2^)5. Correspondence: Chih-Ying Su. MD. Dept of Otolaryngology. Chang Gung Memorial Hospital. No. 123. Ta-Pei Rd. Niao-Sung Hsiang, Kao.<;hiung Hsien.Taiwan. II 12 Su el al. Liser Myoneurectomy for Spasmodic Dysphonia Fig 1. Inlraopenilive endoscopie \ icws uf (ransoni! kiser thyroarylenoid mynneurectumy. A) Endolaryiigciil apixMritnce prior to operation. B) Laser partial resection of left ventricular fold to expo.se whole line v(Kal fold. C) Reseclion of mid- posterior belly of left thyroarytenoid muscle. D) Completion of bilateral thyroar>'tenoid myoneurectomy. effect gradually subsides. Despite efforts to refine stitutional Review Board) included 14 consecutive both surgical and Botox treatments, symptom re- patients who had the presumptive diagnosis of ASD lief in ASD with tremor remains suboptimal.^' None when referred. Informed consent was obtained from of the available interventions at the nerve and end all patients before surgery. Detailed history-taking organ offer a definitive cure. As the outcome after and physical examinations were performed before all of these procedures is less than optimal, new ap- operation, including subjective and objective vocal proaches to the treatment of ASD that may offer a function assessments and videolaryngostroboscopy. long-term solution need to be developed. Surgical Procedure. All 14 patients underwent The ideal treatment for ASD would improve both transoral laser partial resection of the ventricular sound production and voice quality without interfer- folds, followed by myoneurectomy of bilateral thy- ence with the sphincter function of the glottis, and roarytenoid muscles. Under general anesthesia, a would provide long-lasting benefit. In an attempt to direct laryngoscope was inserted to expose the true achieve this goal, we designed a transoral approach vocal folds and ventricular folds (Fig IA). An op- to laser partial resection of ventricular folds fol- erating microscope and a carbon dioxide laser (10 lowed by myoneurectomy of bilateral thyroaryte- W, continuous mode, and slightly defocused) were noid muscles. This procedure has not been fully ad- used to perform partial resection of the ventricular dressed in the literature. fold to expose the entire true vocal fold (Fig IB). PATIENTS AND METHODS Then the middle and posterior thirds of bilateral thy- Clinical Data. This study (approved by our In- roarytenoid muscles were vaporized or resected (Fig Su el al. La.ser Myoncurcctoiny for Spasmodic Dxsphonhi 13 Fig 2. A) Diagrani demonslrates ihiit left veiuricular fold ;itid middle belly of thyroarytenoid muscle are partially resecled by laser. Terminal fibers of recurrent laryngeal nerve among muscle bundles are also vaporized. B) Terminal neurovascular bundle (arrow) among deep muscle bundles was visualized during laser surgery. Laser vaporization of nerve fibers usually elicited strong twitching of muscle. IC.D). Care was taken not to damage the vocalis Laboratory (core model CSL4300B. KayPENTAX, ligaments, arytenoid cartilages, or lateral cricoary- Lincoln Park, New Jersey). The aerodynamic pa- tenoid muscles {Figs ID and 2A). During laser sur- rameters of mean airflow rate and maximal phona- gery on the deep muscle bundles, terminal nerve fi- tion time were measured with the circumferential- bers were frequently found among the musele bun- ly vented pncumotachograph mask and differential dles. The nerve fibers, if any. were vaporized as well transducers of the Aerophone system (Aerophone 11. (Fig 2B. arrow). Laser vaporization of the nerve fi- model 6800. KayPENTAX). bers usually elicited a strong twitching of the mus- cles. In some cases, bleeding from the small vessels Perceptual assessments were determined by con- occurred, which could be readily stopped by cauter- sensus of a speech pathologi.st and a senior laryngol- ization. Fibrin glue or suture material was not ap- ogist who listened to the recorded speech samples. plied to the surgical wound in any patient. The pro- Judgments of voice quality and ability to commu- cedure was usually accomplished within 1 hour. Tbe nicate were made on the basis of overall grade (G). patients were requested to maintain voice rest for roughness (R), breathiness (B). interruption or break several days to 1 week after the operation. (I), .strain (S). and tremor (T). Clinical severity be- fore and after surgery was evaluated with a 3-point Vocal Function Studies. Vocal function studies ordinal scale on which "()"" indicated normal. "1" and videolaryngostroboscopy were performed as mild dysfunction. "2" moderate dysfunction. "3" previously described.^""^ The patients were assessed severe dysfunction, and "4" profound dysfunction. 1 or 2 weeks after operation and again approximate- Clinical subjective judgment of the improvement of ly 1.3.6. 12. 18, and 24 months after operation. All voice quality and communication after surgery was data were prospectively recorded in a database, in- assessed by a patient self-rating scale. The findings cluding associated symptoms, surgical procedures, were classified into categories of normal, markedly complications, vocal function test results, and surgi- improved, moderately improved, slightly improved, cal outcomes. The vocal assessments involved per- not changed, and worse. ceptual judgment of voice quality,