EFFECT OF DIGITALIS ON CONDUCTION DYSFUNCTION IN PELIZAEUS-MERZBACHERDISEASE

We studied the effect of digitalis on nerve conduction dysfunction in Pelizaeus-Merzbacher disease (PMD). The patients were three Japanese b oys with PMD, aged 7-10 years. Digitalis was administered orally in a daily dose of 0.06 mg/kg for 2 consecutive months, and the obtained se rum concentrations ranged from 0.33 to 0.55 ng/ml. The digitalis thera py induced slight improvement of severe dysarthria and cognitive dysfu nction in the two older patients. Electrophysiological examinations re vealed the following results: In brainstem auditory evoked potentials (BAEPs), while waves II (or III) to V were absent before treatment, on treatment all waves of BAEPs except a wave IV were restored in all pa tients. While visual evoked potentials (VEPs) in response to transient flash stimulation showed markedly prolonged latencies before treatmen t, digitalis produced a mild, although not statistically significant, shortening of the latency of N160. There were also no significant chan ges in inter-peak amplitudes of VEPs. Transcranial cortical magnetic s timulation continued to fail to elicit motor evoked potentials of the first dorsal interosseous muscles in all patients. Thus, although the serum concentrations were insufficient to elicit favorable therapeutic effects, digitalis therapy provided slight relief of clinical symptom s with evidence of improvement of conduction dysfunction. It is sugges ted that patients with PMD may respond to symptomatic treatment modula ting nerve conduction.