The Analysis of Treatment with Acyclovir and Prognostic Factors on Idiopathic Facial Mononeuropathy Using Sunnybrook Scale

Kim, Ho Jung; Kim, Byung Jo; Koh, Seong Beom; Park, Kun Woo; Lee, Dae Hie; Lee, Seung Hwan

Abstract

BACKGROUND: Based on a recent study showing that the reactivation of HSV-1 may be one of the possible pathogenesis of idiopathic facial mononeuropathy, antiviral therapy has been suggested as a good treatment modality. However, the efficacy of antiviral therapy is still controversial. This argument may be caused by the absence of a reliable system of grading facial nerve paralysis. We performed this study to investigate the therapeutic effects of an antiviral agent and possible prognostic factors using the Sunnybrook scale.
METHODS
Patients with idiopathic facial mononeuropathy were divided as two groups according to the treatment regimens (Acyclovir & Steroid vs. Steroid only). Clinical efficacy was evaluated using the House-Brackmann grading system and Sunnybrook scale. Electrodiagnostic studies including the blink reflex, facial nerve conduction study, and facial nerve excitability test were performed. The clinical improvement rate between the two groups and the usefulness of the electrodiagnostic studies as prognostic factors were analyzed.
RESULTS
No significant differences of the clinical improvement rate was revealed with a 70% improvement rate for the Acyclovir treatment group and 84% for the steroid only group. Among electrodiagnostic studies, the compound muscle gamma action potential (CMAP) amplitude (=0.637, p=0.000) and nerve excitability =0.688, gamma test (p=0.000) on 2 weeks showed significant correlations to the final Sunnybrook score. There is good correlation between the two facial nerve grading systems.
CONCLUSIONS
Acyclovir may not be effective in the recovery of idiopathic facial mononeuropathy. CMAP amplitude and nerve excitability tests on 2 weeks may provide valuable prognostic factors. The Sunnybrook scale may be useful as a facial grading system.