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Effect of 4-aminopyridine on gravity dependence and neural integrator function in patients with idiopathic downbeat nystagmus


Sander, T; Sprenger, A; Marti, S; Naumann, T; Straumann, D; Helmchen, C (2011). Effect of 4-aminopyridine on gravity dependence and neural integrator function in patients with idiopathic downbeat nystagmus. Journal of Neurology, 258(4):618-22.

Abstract

Downbeat nystagmus (DBN) is a frequent sign in patients with cerebellar degeneration. It consists of an upward drift of the eye that does not depend on vertical head position (spontaneous drift, SD), a gravity-dependent component (GD), and a gaze-evoked drift reflecting gaze-holding impairment (deficient neural integrator function). The potassium-channel blocker 4-aminopyridine (4-AP) is reported to reduce DBN in patients with cerebellar atrophy but with little or no effect in patients with idiopathic DBN. We prospectively studied the effect of 4-AP on all three components in a large (n = 24) group of the clinically frequent idiopathic DBN. DBN was reduced by 22-31% when the head was off the head erect position. In contrast, there was no effect on vertical gaze-evoked drift. This indicates the therapeutic efficacy of 4-AP not only in patients with cerebellar atrophy but also in idiopathic DBN patients. This beneficial effect, which might be missed when gravity-dependent head positions are not tested, was not related to an improvement of gaze-holding deficit. We suggest it may be related to the restored inhibition of the overacting otolith-ocular reflex.

Abstract

Downbeat nystagmus (DBN) is a frequent sign in patients with cerebellar degeneration. It consists of an upward drift of the eye that does not depend on vertical head position (spontaneous drift, SD), a gravity-dependent component (GD), and a gaze-evoked drift reflecting gaze-holding impairment (deficient neural integrator function). The potassium-channel blocker 4-aminopyridine (4-AP) is reported to reduce DBN in patients with cerebellar atrophy but with little or no effect in patients with idiopathic DBN. We prospectively studied the effect of 4-AP on all three components in a large (n = 24) group of the clinically frequent idiopathic DBN. DBN was reduced by 22-31% when the head was off the head erect position. In contrast, there was no effect on vertical gaze-evoked drift. This indicates the therapeutic efficacy of 4-AP not only in patients with cerebellar atrophy but also in idiopathic DBN patients. This beneficial effect, which might be missed when gravity-dependent head positions are not tested, was not related to an improvement of gaze-holding deficit. We suggest it may be related to the restored inhibition of the overacting otolith-ocular reflex.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Neurology
04 Faculty of Medicine > Neuroscience Center Zurich
04 Faculty of Medicine > Center for Integrative Human Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Date:2011
Deposited On:26 May 2011 11:33
Last Modified:05 Apr 2016 14:55
Publisher:Springer
ISSN:0340-5354
Publisher DOI:https://doi.org/10.1007/s00415-010-5806-y
PubMed ID:21057959

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