Effect of 4-aminopyridine on upbeat and downbeat nystagmus elucidates the mechanism of downbeat nystagmus.
The potassium channel blocker 4-aminopyridine (4-AP) restored vertical smooth pursuit and gaze holding in light in one patient with upbeat (UBN) and in one with downbeat nystagmus (DBN). Without a visible target, however, 4-AP had no effect on UBN, but DBN vanished. We hypothesize that this difference in the effects of 4-AP, which is known to increase the excitability of cerebellar Purkinje cells, can be attributed to the different lesion sites involved in UBN and DBN.
Glasauer
Stefan
S
Center for Sensorimotor Research, Department of Neurology, Ludwig-Maximilian-University, Munich, Germany. sglasauer@nefo.med.uni-muenchen.de
Strupp
Michael
M
Kalla
Roger
R
Büttner
Ulrich
U
Brandt
Thomas
T
D015761:4-Aminopyridine / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D005133:Eye Movements / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008636:Mesencephalon / Q000293:injuries* / Q000473:pathology; D009760:Nystagmus, Physiologic / Q000187:drug effects / Q000502:physiology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D014786:Vision Disorders / Q000209:etiology* / Q000503:physiopathology
D026902:Potassium Channel Blockers; D015761:4-Aminopyridine