[Remote effect in patients with thalamic stroke. A study using positron emission tomography]

The purpose of this study was to investigate the functional relation between the thalamus and other cortical regions in patients with thalamic stroke from the view of cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO2) using positron emission tomography (PET). Twenty patients with thalamic stroke (right lesion = 8, left lesion = 12) and 7 normal controls were studied. Five patients were diagnosed as having thalamic infarction, and 15 (patients were diagnosed) as having thalamic hemorrhage by X-CT and/or MRI scan. Regional cerebral blood flow and cerebral metabolic rate of oxygen were measured by PET using C15O2 and 15O2 steady state inhalation technique. In the left thalamic stroke group, CMRO2 was significantly decreased in the left cingulate, superior frontal, superior temporal, middle temporal, medial occipital, and thalamic regions, compared with the normal control group. In the right thalamic stroke group, CMRO2 was decreased in the left cingulate, medial occipital, right hippocampal, thalamic, and the bilateral cerebellar regions, compared with the normal control group. In the left thalamic stroke group. CBF was decreased significantly in the left cingulate, middle temporal, hippocampal, thalamic, and right cerebellar regions, compared with the normal control group. In the right thalamic stroke group, CBF was significantly decreased in the right hippocampal, thalamic and left cerebellar regions compared with the normal control group. These results indicate that CBF and CMRO2 decrease in some distant regions from thalamic lesions, perhaps due to a disconnection of neuronal fiber. Especially in the left thalamic stroke group, CMRO2 was decreased in the ipsilateral temporal regions. This result suggests that there are more intimate functional fiber connections between the thalamus and temporal cortex in the left hemisphere than in the right hemisphere.