IPSILATERAL THALAMIC DIASCHISIS AFTER MIDDLE CEREBRAL-ARTERY INFARCTION

The significance of ipsilateral thalamic diaschisis (ITD) among patien ts with chronic, stable middle cerebral artery (MCA) infarcts was inve stigated. Twenty eight subjects with chronic MCA infarction and twenty two normal controls were studied with positron emission tomography (P ET), using the steady state technique with O-15. Stroke patients were subdivided into a group with ITD (n = 12) and a group without ITD (n = 16). Patients with ITD had greater decreases of regional blood flow ( rCBF) and oxygen consumption (rCMRO(2)) in the infarcted MCA territory , compared to MCA infarction without ITD. The neurological deficits at the time of PET scanning were similar between both groups. Extent of infarction by CT brain scan appeared more predominant in peri-insular regions of patients with ITD, while in non diaschisis patients infarct s were more widely distributed throughout the MCA territories. Occurre nce of ITD and of crossed cerebellar diaschisis (CCD) did not correlat e. Occurrence of ITD seems to be linked to diffuse reductions of blood now and oxygen metabolism in cortical territories of the MCA. Mechani sms of ITD were different from those of CCD.