Effects of vagal nerve stimulation on vocal functions

Purpose: This study aims to describe the subjective and objective effects of Vagal Nerve Stimulation (VNS) on vocal functions Method: We studied 14 patients (7 males/ 7 females) affectred by drug resistant epilepsythat underwent VNS implantation. Mean patients agewas 41 years. Latency from implantation ranged from 1 to 8 years. Patients subjecticve disturbs have been investigated performing an unstructured colloquium and by self administered questioner. Vocal functions have been studied by means of larygeal fibroscopy (LF) and vocal analysis (MultiDimensionalVoiceProgram Kay Pentax TM) both at rest and dring VNS stimulation. Result: (a) immediatly after implantation patients (n 4) referred chronic dysphonia +/) dysphagia, that could periodically and intermittently worsen, in relation to VNS discharge. Chronic disturbs gradually recovered 2–3 months after surgery, whilst in most cases intermittent dysphonia was also present for 3–10 days after each following increment of the VNS amperage. LF and VA documented unilateral hypomobility of vocal cord and phonological alteration while the stimulator was switched off; disturbs worsened during VNS discharges. (b) patients studied (n 10) after 1–8 years from implantation, occasionally referred vocal disturbs (2 patients presented sporadically intermittent dysphonia). LF and VA documented in 9/10 cases a residual hypomobility of the vocal cord, functionally compensated from the contralateral vocal cord hyperadduction. Conclusion: We documented that both surgergical procedure and electrical stimulation of the vagal nerve can perturb the motility of the vocal cord homolateral t the side of implantation. This incostantly produces negative effects on vocal productions and occasionally is referred by patients as a chronic disturb.