Eye and head torsion is affected in patients with midbrain lesions

The midbrain has been shown to contain crucial nuclei for the control of vertical and torsional eye movements. Recent studies in monkeys demonstrated that midbrain lesions also affect head movements during gaze saccades, but so far clinical reports on the matter have been missing. We measured 3D eye and head movements in two patients with oculomotor deficits due to unilateral midbrain lesions and in healthy control subjects. Subjects had (1) to perform head-free target directed gaze saccades (head-free task), and (2) to point to the target with a head-laser (head-only task). The patients had vertical eye movement deficits, which were not compensated by the head. Three-dimensional analysis revealed torsional deviations from the normal range of movements for both, the eye and the head movements.