Cerebral blood flow in patients with various symptoms of hemispatial neglect following ischemic stroke

BACKGROUND AND PURPOSE: The most common cause of hemispatial neglect (HN) is cerebral infarction. It can be induced by lesions in many different regions of the right hemisphere. The purpose of this article was to determine the prevalence of post-stroke HN, its clinical picture, and neuroanatomical correlates. MATERIAL AND METHODS: Forty-six stroke patients with a focal right-hemisphere lesion were studied. Neglect in visual domain, assessed with a battery of drawing, line bisection and shape cancellation tests, was observed in 20 cases. The single-photon emission-computed tomography (SPECT) images of the brain were obtained with 740 MBq (20 mCi) of Tc-99m-labeled ECD on a triple-headed gamma camera. RESULTS: The most sensitive measure of HN was the cancellation test, which all neglect patients performed poorly. Twelve patients, classified as mildly impaired, showed no significant rightward deviation on line bisection, but they showed left visual neglect on the cancellation test. Reverse dissociation was not noted. Performance on a clock-drawing test revealed HN only in two patients, who showed also evidence of HN on other tests. Thereby, some of the tests seem to be more difficult or more sensitive to impairment. The critical area of perfusion abnormalities in all neglect patients were frontal lobe and striatum on the right. In severe HN, SPECT images evidenced the most extensive hypoperfusion throughout the perisylvian region and subcortical structures of the right hemisphere. Although parietal cortex was affected in patients with moderate to severe HN, it was spared in the rest. CONCLUSIONS: HN was a relatively common symptom of vascular right-hemisphere damage (43% of the patient population). HN was a complex disturbance in terms of its clinical manifestation and neuroimaging correlates. Our findings challenge the classical notion that damage to the parietal cortex is critically associated with HN. Instead, our results support the model attributing hemispatial neglect to a defect in a cortico-striato-thalamo-cortical loop. Also, the present study highlights the usefulness of cerebral blood flow SPECT imaging as a diagnostic aid in the post-stroke deficits of cognition following right-hemisphere damage.