Neurophysiological evaluation of acute facial paralysis in children

Abstract

Objective evaluation of facial nerve paralysis represents a unique challenge to the clinician. Electroneurography (ENoG) and the acoustic reflex (AR) have been widely used as neurophysiological tests in an assessment of facial nerve function. However, ENoG or AR alone does not suffice diagnostic and prognostic purposes of facial function evaluation in children. To further investigate the diagnostic aspects of facial nerve paralysis, the prognostic value of AR and ENoG, and the time course of the disease in pediatric population, a series of 30 children with acute facial paralysis were investigated by correlation of findings from video-taped House-Brackmann facial grading system, AR and ENoG. The results showed that AR was absent or abnormal for thresholds in 68.2% of patients with Bell's palsy and normal middle ear function. Shorter duration and higher percentage of recovery were found in the children with a normal AR than those with an abnormal AR. Three children showed an abnormal tympanogram and hearing loss associated with acute facial paralysis. These findings should alert the clinician to the presence of a specific, treatable disease in the evaluation of Bell's palsy. The percentage of electroneurographic response varied with different days after onset. ENoG showed minimal responses at weeks 1–3 after onset of Bell's palsy in most patients. The study of the time-course in the children with Bell's palsy demonstrated a functional gap in the early (< 1 week) and late clinical stage (after 6 weeks) of the disease, suggesting that ENoG predicted well only during weeks 1–4 after onset. In general, ENoG showed a good recovery in children, however, recurrent Bell's palsy becomes a concern. The need for neurophysiological follow-up for possible incomplete recovery of the facial nerve is emphasized. It is recommended that AR and ENoG should be included in the diagnostic workup when evaluating pediatric facial function.