Evaluation of peripheral vocal cord paralysis by electromyography.

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.