Effect of long-term electrical stimulation on motor recovery and improvement of clinical residuals in patients with unresolved facial nerve palsy

PURPOSE: This study investigated the efficacy of a pulsatile electrical cur rent to shorten neuromuscular conduction latencies and minimize clinical re siduals in patients with chronic facial nerve damage caused by Bell's palsy or acoustic neuroma excision. SUBJECTS: The study group included 12 patients (mean age 50.4 +/- 12.3 year s) with idiopathic Bell's palsy and 5 patients (mean age 45.6 +/- 10.7 year s) whose facial nerves were surgically sacrificed. The mean time since the onset of paresis/paralysis was 3.7 years (range 1 - 7 years) and 7.2 years (range 69 years) for the Bell's and neuroma excision groups, respectively. METHOD AND PROCEDURES: Motor nerve conduction latencies, House-Brackmann fa cial recovery scores, and a 12-item clinical assessment of residuals were o btained 3 months before the onset of treatment, at the beginning of treatme nt, and after 6 months of stimulation. Patients were treated at home for pe riods of up to 6 hours daily for 6 months with a battery-powered stimulator . Stimulation intensity was kept at a submotor level throughout the study. Surface electrodes were secured over the most affected muscles. Groups and time factors were used in the analyses of the 3 outcome measures. RESULTS: No statistical differences were found between the two diagnostic g roups with respect to any of the 3 outcome measures. Mean motor nerve laten cies decreased by 1.13 ms (analysis of variance test, significant P = 0.000 1). House-Brackmann scores were also significantly lower (Wilcoxon signed r ank test, P = 0.0003) otter treatment. Collective scores on the 12 clinical impairment measures decreased 28.7 +/- 8.1 points after 6 months (analysis of variance test, significant P = 0.0005). Eight patients showed more than 40% improvement, 4 better than 30%, and 5 less than 10% improvement in res iduals score. CONCLUSION: These data are consistent with the notion that long-term electr ical stimulation may facilitate partial reinnervation in patients with chro nic facial paresis/paralysis. Additionally, residual clinical impairments a re likely to improve even if motor recovery is not evident.