Abstract
Confidence in the reliability of laryngeal electromyography (EMG) to predict recovery is critical if this tool is to be used to select the type and timing of surgical intervention. The characteristics of EMG of 14 patients with unilateral vocal fold paralysis were assessed to determine which factor or combination of factors would be most useful in determining prognosis. We examined the duration, amplitude, waveform morphology, root-mean-square, and time interval from onset to EMG recording. The results supported the concept that EMG recordings are valuable in determining prognosis if it is performed prior to 6 months and preferably within 6 weeks of onset of laryngeal paralysis. A positive prognosis for laryngeal recovery was indicated when the following EMG features were present in the immobile vocal fold: 1) normal motor unit waveform morphology, 2) overall EMG activity characterized by an RMS value greater than 40 uV in any one task, and 3) no electrical silence during voluntary tasks. Based on this criteria our overall correct prognostic rate was 89%.

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