Validity of Late-Term Electroneurography in Bell's Palsy

Objective To evaluate the validity of early (within 3 wk) and late-term (after 3 wk) electroneurography (ENoG) findings in Bell's palsy (BP) to predict the prognosis. Study Design Retrospective case review. Setting Tertiary referral center. Patients Patients with peripheral facial paralysis with no identified cause. All patients were given the same treatment. Intervention(s) House Brackmann (HB) grading and ENoG. Main Outcome Measures The records of 38 patients with BP were retrospectively analyzed. This study included only those patients who had been followed up for at least 4 months on a regular basis or until complete recovery. ENoG was performed for orbicularis oculi and orbicularis oris muscles and degeneration ratio was calculated separately. Correlation between HB grading and ENoG findings, relationship between duration for maximum recovery and ENoG findings, and also initial HB grading and recovery rate were investigated. Results Complete recovery rate was significantly higher in patients with HB grades I to III at initial examination. A significant correlation was found between HB grading and degree of ENoG degeneration at the 7th and 14th days of FP. Patients with degeneration less than 80% for orbicularis oculi and less than 65% for orbicularis oris had significantly better and faster recovery than those with higher level of degeneration (p < 0.05). Conclusion ENoG and HB grading during first to fourth weeks of BP are useful prognostic indicators. Serial ENoG examinations are recommended to predict the status of neural degeneration and the prognosis of the palsy. However, ENoG in late term may not be compatible with clinical facial function.