4-aminopyridine restores visual ocular motor function in upbeat nystagmus.
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.
Glasauer
S
S
Department of Neurology, Klinikum Grosshadern, Marchioninistrasse 23, 81377 Munich, Germany. sglasauer@nefo.med.uni-muenchen.de
Kalla
R
R
Büttner
U
U
Strupp
M
M
Brandt
T
T
D015761:4-Aminopyridine / Q000494:pharmacology* / Q000627:therapeutic use*; D000328:Adult; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D009759:Nystagmus, Pathologic / Q000188:drug therapy*; D026902:Potassium Channel Blockers / Q000494:pharmacology* / Q000627:therapeutic use*; D011689:Purkinje Cells / Q000502:physiology; D016896:Treatment Outcome
D026902:Potassium Channel Blockers; D015761:4-Aminopyridine