UNILATERAL SACCADIC PURSUIT IN PATIENTS WITH SENSORY STROKE - SIGN OFA PONTINE TEGMENTUM LESION

Background and Purpose-Pure hemisensory syndrome can be caused by smal l strokes occurring in a number of regions, including the thalamus and pens. Differentiation of the pontine sensory syndrome from the thalam ic sensory syndrome has generally been made on the basis of distributi on of sensory loss and involvement of specific sensory modalities but not without uncertainties and difficulties. Because the pontine tegmen tum plays a pivotal role in generating horizontal eye movement, we att empted to discriminate these 2 syndromes by analyzing horizontal eye m ovements in stroke patients with pure hemisensory syndrome. Methods-Ho rizontal saccade, pursuit, vestibule-ocular reflex (VOR), and VOR canc ellation (VORC) were evaluated using electro-oculography in 6 patients with hemisensory syndromes, 3 due to pontine stroke and 3 due to thal amic stroke, and all were verified by MRI or CT. In addition, somatose nsory evoked potentials (SEPs) were recorded. Results-Smooth pursuit a nd VORC directed toward the side of the lesion were impaired unilatera lly in patients with pontine sensory stroke, whereas those 2 movements were intact bilaterally in patients with thalamic sensory stroke. Sac cade and VOR were preserved in all patients. SEPs were normal in all p atients with pontine and thalamic sensory strokes. No difference was f ound in the pattern of sensory disturbance between the 2 types of stro ke patients. Conclusions-Ipsilateral impairment of the smooth pursuit system may be a sign of a pontine lesion in patients with hemisensory stroke.