Electroneurographic facial muscle pattern in Bell's palsy.

To study the electroneurographic facial muscle pattern in Bell's palsy over time, electroneurographic recordings in the frontalis, orbicularis oculi, nasalis, and mentalis muscle regions were performed early (mean, day 11) and 1 and 3 months after the onset of the condition in 30 consecutive patients. The correlation between facial muscle electroneurographic recordings over time was also calculated. An additional aim was to assess whether further prognostic information could be obtained by electroneurographic recordings in more than one facial region. The recovery pattern was similar in all 4 facial regions. Initially, the correlation between the facial recordings was weak (r = 0.20-0.27), but it was improved at follow-up examinations (r = 0.33-0.65). Favorable outcome in 23 of 24 patients (96%) could have been predicted by the initial nasalis and/or mentalis recordings. The gap between patients with favorable outcome and patients with unfavorable outcome increased when the average electroneurography values were calculated from 1, 2, and 4 muscle recordings (4%, 8%, and 15%, respectively). Our results indicate that in Bell's palsy, electroneurographic examination of more than one facial muscle region may add prognostic information and that the degree of degeneration is initially different in the nerve branches.

House-Brackmann and Yanagihara grading scores in relation to electroneurographic results in the time course of Bell's palsy.

The results of House Brackmann and Yanagihara grading were compared with electroneurographic (ENoG) data in 30 consecutive patients with Bell's palsy. The examinations were made on mean days 11, 36 and 99. Twenty-four patients had a favourable outcome (Yanagihara > or = 36 at three months). Based on our observations, 23 (96%) of these could have been predicted by ENoG, 18 (75%) by Yanagihara grading and 6 (25%) by House Brackmann grading. Initially, the relative House Brackmann scores showed a slightly milder palsy than the Yanagihara scores, but in the follow-up period the gradings were almost identical. The mild palsies, defined on the initial ENoG results, initially demonstrated relatively less nerve dysfunction on ENoG than the clinical grading; by the first follow-up, the ENoG and clinical grading had both returned to normal. The intermediate palsies had almost the same initial relative clinical and ENoG values, but at the first follow-up (mean day 36), the facial function had returned to normal despite abnormally reduced, but improved, ENoG values. In the severely affected patients, the follow-up studies showed an improved clinical function but ENoG values still demonstrated a high degree of degeneration (slightly improved at second follow-up). In this study, patients with a favourable outcome were best predicted with ENoG. Clinical identification of these patients was more accurate with Yanagihara than with House Brackmann. Furthermore, in all three groups a clinical improvement, due to the release of neurapraxia, was noted at the first follow-up. The slow ENoG improvement noted at follow-up was probably due to nerve regeneration by collateral sprouting. Based on the time course of our ENoG findings, it appears that patients with a high degree of degeneration at both the initial examination and first follow-up have a poorer prognosis.