title: Refractory Dysphonia Due to Isolated Cricothyroid Muscle Dystonia.
abstract: OBJECTIVE
  To demonstrate the utility of electromyography (EMG) in the evaluation and management of treatment-resistant dysphonia.
  
  
  METHODS
  We report a case of refractory dysphonia in which EMG was used to identify and treat isolated cricothyroid (CT) dystonia.
  
  
  RESULTS
  The patient, a healthy 43-year-old woman, presented with 9 months of progressive hoarseness. Her symptoms were present across vocal tasks but were particularly bothersome while dictating. On presentation, her voice was rated grade 3, roughness 3, breathiness 1, asthenia 0, and strain 3 (G3R3B1A0S3). Videostroboscopy was remarkable for hyperfunction. Voice therapy was not beneficial despite appropriate effort. Microdirect laryngoscopy revealed no evidence of structural pathology. The patient was referred for EMG because of her normal examination and failure to improve with therapy. The CT muscle demonstrated an increased latency of 750 ms in all vocal tasks. One month after CT injection with 3 units of botulinum toxin (BTX), her voice was improved. Perceptual voice evaluation was rated G1R1B0A0S1. Voice Handicap Index improved from 87 to 35.
  
  
  CONCLUSIONS
  In the absence of structural pathology, EMG can be a useful adjunct in the diagnosis of dysphonia that persists despite adequate trials of voice therapy. To our knowledge, this is the only report of laryngeal dystonia due to isolated CT dysfunction successfully treated with BTX.
authors.affiliation: Department of Otolaryngology, University of Kansas Medical Center, Kansas City, Kansas. Electronic address: skraft3@kumc.edu.
authors.forename: Shannon
authors.initials: S
authors.lastname: Kraft
authors.affiliation: Department of Otolaryngology, Oregon Health and Science University, Portland, Oregon.
authors.forename: Jana
authors.initials: J
authors.lastname: Childes
authors.affiliation: Department of Otolaryngology, University of Washington, Seattle, Washington.
authors.forename: Allen
authors.initials: A
authors.lastname: Hillel
authors.affiliation: Department of Otolaryngology, Oregon Health and Science University, Portland, Oregon.
authors.forename: Joshua
authors.initials: J
authors.lastname: Schindler
mesh_terms: D065087:Acetylcholine Release Inhibitors / Q000008:administration & dosage; D000328:Adult; D001905:Botulinum Toxins / Q000008:administration & dosage; D004185:Disability Evaluation; D055154:Dysphonia / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D004421:Dystonia / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D007821:Laryngeal Muscles / Q000187:drug effects / Q000503:physiopathology*; D011237:Predictive Value of Tests; D020127:Recovery of Function; D016896:Treatment Outcome; D014833:Voice Quality
chemical_list: D065087:Acetylcholine Release Inhibitors; D001905:Botulinum Toxins
keywords: Cricothyroid muscle; Laryngeal dystonia; Laryngeal electromyography; Spasmodic dysphonia