[The value of laryngeal electromyography in the prognosis of vocal cord paralysis].

Objectives: We investigated the value of laryngeal electromyography (EMG) in monitoring patients with vocal cord paralysis.

Patients And Methods: Cricothyroid and thyroarytenoid muscles of 40 patients (10 females, 30 males; mean age 32 years; range 18 to 61 years) with vocal cord paralysis were monitored with laryngeal electromyography. The patients were divided into two groups according to time to presentation after symptom onset, i.e. within 1-3 months (group 1; n=14), and after at least 12 months (group 2; n=26). Electromyography was repeated every three months in group 1, and in the third and sixth months in group 2.

Results: Initial EMG examinations showed polyphasic reinnervation potentials and partial axonal degeneration in 21 laryngeal nerves in group 1. Recovery was expected in these patients. Repeat EMGs revealed normal findings in 17 laryngeal nerves, yielding a prognostic estimation of 80.9% (17/21). In group 2, none of the patients demonstrated polyphasic potentials or motor unit potentials suggesting reinnervation on admission. The earliest and latest recoveries were observed in the fourth and eleventh months (mean 6.4 months) in group 1, respectively. However, group 2 patients were followed-up for at least 18 months after the onset of their symptoms and none manifested clinical and electrophysiologic improvement.

Conclusion: Our data suggest that EMG is a useful technique in the estimation of prognosis of patients presenting in the early period of vocal cord paralysis.