Thalamocortical diaschisis: Single-photon emission tomographic study of cortical blood flow changes after focal thalamic infarction

Seven patients with nonhemorrhagic thalamic infarctions were studied with regional cerebral blood flow (rCBF) measurement, neuroimaging, and neuropsychologic testing to investigate the following relationships: (a) location of thalamic infarction and site of abnormal cortical blood flow; (b) neuropsychologic deficits and abnormal rCBF; and (c) recovery from neuropsychologic deficits and rCBF. In three patients with unilateral lesions and three with asymmetric bilateral lesions, cortical rCBF decreased ipsilateral to the unilateral or larger lesion. Acutely, neuropsychologic deficits and cortical rCBF abnormalities correlated in laterality—e.g., aphasic patients had left-sided diaschisis. In one patient, cognitive improvement was accompanied by a decrease in size of the thalamic lesion on magnetic resonance imaging but rCBF did not improve. We conclude that thalamic deafterentation of cerebral cortex may cause focal reduction of rCBF and cognitive dysfunction but that clinical recovery can occur despite persistence of cortical diaschisis.