Evaluation of peripheral vocal cord paralysis by electromyography

Abstract

Objective: To analyze the predictive value of electromyography (EMG) after peripheral vocal cord paralysis and to estimate regeneration time.

Study design: Retrospective study based on electromyographic data and medical chart review of university based ENT hospitals.

Methods: EMG results of 448 patients were classified into neuropraxia, axonotmesis/neurotmesis, or not classifiable and followed until final outcome. Final outcome was classified electromyographically into restitutio ad integrum, defective healing, or not classifiable.

Results: The etiology of the paralysis was thyroid gland surgery in 42.9% and other iatrogenic lesions in 11.8%. Idiopathic paralysis was found in 20.3%. Mean follow-up time was 4.8 months. Initial EMG findings were neuropraxia in 31.0%, axonotmesis/neurotmesis in 40.8%, and not classifiable in 28.1%. Restitutio ad integrum was detected by EMG in 17.6% and defective healing in 43.3%. In 39.1%, the outcome could not be classified. The positive predictive value of EMG was 97% and the negative predictive value 60%. The outcome depended significantly on the initial EMG result (P < .0001) but not on the etiology (P = .737) of the paresis. Regeneration time after neuropraxia was 4.0 months and after axonotmesis/neurotmesis 5.6 months.

Conclusion: Laryngeal EMG has a high predictive value for acute peripheral vocal cord paralysis. The outcome can be predicted more reliably by means of EMG than by analysis of the etiology of the lesion.