Journal Article

Vergence deficits in patients with cerebellar lesions

T. Sander, A. Sprenger, G. Neumann, B. Machner, S. Gottschalk, H. Rambold and C. Helmchen

in Brain

Published on behalf of The Guarantors of Brain

Volume 132, issue 1, pages 103-115
Published in print January 2009 | ISSN: 0006-8950
Published online November 2008 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awn306
Vergence deficits in patients with cerebellar lesions

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The cerebellum is part of the cortico–ponto–cerebellar circuit for conjugate eye movements. Recent animal data suggest an additional role of the cerebellum for the control of binocular alignment and disconjugate, i.e. vergence eye movements. The latter is separated into two different components: fast vergence (to step targets) and slow vergence (to ramp and sinusoidal targets). The aim of this study was to investigate whether circumscribed cerebellar lesions affect these dynamic vergence eye movements. Disconjugate fast and slow vergence, conjugate smooth pursuit and saccades were binocularly recorded by a scleral search coil system in 20 patients with acute cerebellar lesions (all ischemic strokes except for one) and 20 age-matched healthy controls. Patients showed impairment of slow vergence while fast vergence was unaffected. Slow vergence gain to sinusoidal targets was significantly reduced, both in convergence and divergence direction. Divergence but not convergence velocity to ramp targets was reduced. Conjugate smooth pursuit eye movements to sinusoidal and to step-ramp targets were impaired. Patients had saccadic hypometria. All defects were particularly expressed in patients with vermis lesions. In contrast to recent animal data fast vergence was not impaired in any of our patient subgroups. We conclude that (i) the human cerebellum, in particular the vermis, is involved in the processing of dynamic vergence eye movements and (ii) cerebellar lesions elicit dissociable effects on fast and slow vergence.

Keywords: fast vergence; slow vergence; divergence; vermis

Journal Article.  8219 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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