ABSTRACT
<p><b>OBJECTIVE</b>To investigate the characteristics of laryngeal electromyography and evoked electromyography in vocal fold immobility.</p><p><b>METHODS</b>108 cases of vocal fold immobility were analyzed by clinical manifestation and laryngeal electromyography characteristics, including spontaneous potential activity, motor unit potential (MUP) measurement, recruitment pattern analysis and evoked electromyography evaluation.</p><p><b>RESULTS</b>Neurogenic vocal fold immobility showed a wide variety of abnormal activity. Fibrillation potentials and positive sharp waves were found in patients with laryngeal nerve injuries. For laryngeal paralysis, there was no reaction with LEMG and evoked LEMG. For laryngeal paresis, it showed decreased MUP and decreased recruitment activities with simple pattern recruitment or mixed pattern recruitment, and decreased evoked muscle response potentials were also shown with delayed latency than normal (P < 0.05) in the TA (2.2 +/- 1.0) ms(x +/- s), PCA (2.4 +/- 1.0) ms and lower amplitude in the TA (0.9 +/- 0.7) mV and PCA (1.2 +/- 1.0) mV (P < 0.05). Patients with vocal fold mechanical limitations generally yielded normal LEMG and Evoked LEMG. Patients with neoplastic infiltration of the laryngeal muscles demonstrated decreased LEMG and nearly normal Evoked LEMG with normal latency and lower amplitude.</p><p><b>CONCLUSIONS</b>General EMG and evoked EMG play a crucial role in the diagnosis of vocal fold immobility.</p>