4-aminopyridine restores visual ocular motor function in upbeat nystagmus
- Correspondence to: Dr S Glasauer Department of Neurology, Klinikum Grosshadern, Marchioninistrasse 23, 81377 Munich, Germany; sglasauernefo.med.uni-muenchen.de
- Received 14 May 2004
- Accepted 7 July 2004
- Revised 6 July 2004
Abstract
The effect of the potassium channel blocker 4-aminopyridine (4-AP) on spontaneous upbeat nystagmus (UBN) was investigated with the search coil technique during fixation in different gaze positions and smooth pursuit in a patient before and after ingestion of 10 mg 4-AP. UBN was reduced from 8.6 deg/s to 2.0 deg/s by 4-AP causing subjective relief from distressing oscillopsia, and impaired upward smooth pursuit was restored (gains: before medication 0.38; after medication 0.86). In the dark, UBN was slightly stronger and not affected by 4-AP. We propose that 4-AP improved the function of cerebellar pathways that mediate gaze holding and smooth pursuit by intensifying the excitability of cerebellar Purkinje cells.
Footnotes
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↵* These authors contributed equally to the work.
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This work was supported by the Deutsche Forschungsgemeinschaft (GL 342/1-1) and the Fritz-Thyssen-Stiftung.
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Competing interests: none declared
