Electrophysiologic Pattern of Facial Muscles in Bell's Palsy

얼굴마비에서 얼굴근육의 전기생리학적 양상

Backgrounds: Electrodiagnostic tests have been developed to estimate the degree of facial nerve injury during the acute phase. Side-to-side amplitude comparison with the affected side expressed as a percentage of the nonaffected side has been one of the most valuable electrophysiologic methods of assessing facial nerve functioning. This study was designed to know whether there is any difference in the side-to-side comparison of amplitudes and terminal latencies of the compound muscle action potentials (CMAP) of the facial muscles in the patients with Bell's palsy. Methods: Electroneurographic recordings with surface electrodes on the frontalis, orbicularis oculi, nasalis, and orbicularis oris muscles were made within 2 weeks post-onset (mean, day 7) in 39 patients. Results: Of the 39 Bell's palsy patients, 38 patients (97.4%) recovered satisfactorily within 6 months. The amplitude of CMAP in all patients was not reduced to 10% or less of that of the contralateral healthy muscle. The correlation of amplitude change between four facial muscles was relatively strong, but the correlation of latency change was weak. When the electroneurographic values were compared in the four muscle groups, the general linear models procedure did not show any significant difference for CMAP amplitude and latency changes (p=0.62-0.63). Conclusions: This study did not show any significant clinical advantage of electroneurographic recordings in more than one facial muscle at the early stage of Bell's palsy.