[The prognostic role of electromyography in vocal cord paralysis].

OBJECTIVE

To predict the recovery of vocal cord paralysis (VCP) by using electromyography (EMG).

METHOD: The characteristics of EMG of 46 patients with unilateral VCP were assessed to determine the most useful factors in determining prognosis. The factors include the duration, amplitude, waveform morphology, root-mean-square, and time interval.

RESULT: A positive prognosis for laryngeal recovery was indicated when the following EMG features were present in the immobile vocal fold during voluntary tasks if EMG was performed during 6 months of the onset of VCP: normal motor unit waveform morphology; no electrical silence. This predictive rate is 76%. When the root-mean-square value is greater than 26 microV, the predictive rate is 80%. On the basis of the criteria, all the prognostic rate is 84%.

CONCLUSION

The results support the concept that EMG record is valuable in determining prognosis performed during 6 months of the onset of VCP.