Eye-head co-ordination in patients with Parkinsonism and cerebellar ataxia.

Eye-head co-ordination of patients with Parkinsonism and cerebellar ataxia was investigated and compared with that of normal subjects. In Parkinsonian patients eye-head co-ordination was of the same pattern as normals, with an accurate and stable gaze. Reaction times for both eyes and head, however, were prolonged. It was also noted that the contribution of head movements to gaze shift was abnormally large and that the gaze accuracy was decreased when the head was immobilised. In patients with cerebellar ataxia, gaze was dysmetric, often hypermetric, and was unstable during head movements. The contribution of head movements to gaze was also large. It is concluded that Parkinsonism and cerebellar diseases influence eye-head co-ordination differently.