THE USE OF 4-AMINOPYRIDINE IN TWO COMMON FORMS OF CEREBELLAR NYSTAGMUS: CASE REPORTS

Abstract

Acquired jerk nystagmus in the course of neurological syndromes often causes visual disturbances through the process of oscillopsia. Due to the lack of causal treatment in certain diseases, clinicians use symptomatic drugs in order to reduce the involuntary eye movements.
In the present article we report on two cerebellar patients with nystagmus who received 4-aminopyridine as a symptomatic treatment. The first case was a typical downbeat nystagmus syndrome due to an anti-Yo mediated paraneoplastic cerebellar dysfunction. As shown in electronystagmographic recordings, nystagmic intensity was clearly reduced after drug intake and so did the oscillopsia. On the other side, the second case, a sporadic neurodegenerative cerebellar atrophy with gaze evoked nystagmus, did not respond to 4-aminopyridine.
This differential efficacy of 4-aminopyridine on two kinds of cerebellar nystagmus of different cause reflects the central role of floccular Purkinje neurons in downbeat nystagmus generation.