Facial electroneurography on the contralateral side in unilateral Bell's palsy.

In this study, ten patients who exhibited severe unilateral Bell's palsy of the House-Brackmann grade V underwent facial electroneurography (ENoG) on the contralateral, healthy side. Serial ENoG was conducted in seven consecutive sessions within 6 months at a given current intensity level of stimulation. According to our results, all the patients presented a rise in the maximum compound-action potential (MCAP) amplitude on the healthy side within 20 to 45 days from the onset of the palsy and shortly after the onset of the recovery of the facial function. This was attributed to the central contralateral compensatory process, which restores balanced facial function. Based on our data, a hypothetical model is shown, which demonstrates the clinical course of the contralateral MCAP values and reflects the plasticity effect of the central nervous system after the onset of Bell's palsy.