OCULAR MOTOR ABNORMALITIES IN HUNTINGTONS-DISEASE

We review here the eye movements in patients with Huntington's disease (HD), concentrating upon saccades as they show the most prominent abn ormalities. Inability to suppress reflexive glances to suddenly appear ing novel visual stimuli and delayed initiation of voluntary saccades, including predictive saccades, are early and consistent findings, The se two abnormalities can be interpreted in the context of a model, bas ed upon the idea that the frontal lobes and basal ganglia contribute m ore to the control of voluntary than to reflexive types of saccades. M ost patients eventually also show slow saccades but they are most prom inent when the disease is early onset. Slowing of saccades may reflect involvement of both the higher-level cerebral centers that trigger sa ccades and the areas in the brain stem that produce premotor saccade c ommands. The study of eye movements in HD has led to a fruitful intera ction between basic science and clinical investigation, and has served as a paradigm for examining higher-level defects in saccadic eye move ment control in patients with various degenerative, neurological disea ses or with focal cerebral hemispheral lesions. (C) 1997 Elsevier Scie nce Ltd.