title: Treatment of spasmodic dysphonia with a neuromodulating electrical implant.
abstract: OBJECTIVE
  To investigate the feasibility of an implantable electrical stimulation device to treat spasmodic dysphonia (SD) by neuromodulation of the muscle spindle gamma loop.
  
  
  METHODS
  Prospective case series.
  
  
  METHODS
  Five subjects underwent daily stimulation of the left thyroarytenoid muscle (TA) below the level of α-motor neuron activation (AMNA) for 5 consecutive days. Professional and patient voice evaluations were performed. Transcartilagenous placement of an implantable stimulation device lead was investigated in anesthetized porcine and cadaveric human models.
  
  
  RESULTS
  Three of 5 subjects improved in all categories of evaluation. One subject improved in three of four categories. These four subjects described significant carryover of effect after treatment. The fifth subject evidenced improvement until contracting an upper respiratory infection on day 3. Transcartilagenous electrode placement into the porcine TA with muscle stimulation was successful. The electrode lead was passed from the cadaveric larynx to the mastoid tip in the subplatysma layer with an absence of tension.
  
  
  CONCLUSIONS
  The symptoms of SD improve after electrical stimulation of the TA at levels below AMNA. This is likely through neuromodulation of the muscle spindle gamma loop. Implantation of an electrode into the TA with a postauricular implanted stimulator is feasible with modifications of an already existing device. With further investigation, such a device has the potential to deliver an alternative treatment for SD.
  
  
  METHODS
  4.
authors.affiliation: New York Eye and Ear Infirmary of Mount Sinai, New York, New York, U.S.A.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pitman
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D055154:Dysphonia / Q000175:diagnosis* / Q000628:therapy*; D004599:Electric Stimulation Therapy / Q000295:instrumentation* / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants; D011474:Prosthesis Design; D020127:Recovery of Function; D018570:Risk Assessment; D012494:Sampling Studies; D057566:Self Report; D034421:Sus scrofa; D016896:Treatment Outcome; D014833:Voice Quality
keywords: Spasmodic dysphonia; botulinum toxin; dystonia; electrical stimulation; gamma loop; muscle spindle; neuromodulation