Abstract
This study was designed to investigate the responsible region and the symptomatic flow and metabolism threshold for Broca's aphasia. The cerebral glucose metabolism in three patients with Broca's aphasia was examined by positron emission tomography (PET) using 11C-glucose, and the images of PET were compared with the images of X-CT on the responsible region for aphasia. In two patients, both X-CT and PET demonstrated abnormal findings in the region which is generally thought to be responsible for Broca's aphasia, that was Broca's area, including cortex and subcortex in the anterior region to Sylvian fissure. In one patient, PET images demonstrated low 11C accumulated area in the above mentioned region, and this region was isodensity on the images of X-CT.
Regional cerebral blood flow (rCBF) and oxygen metabolic rate (rCMRO2) were measured by PET using 150 steady state method in eight patients with Broca's aphasia and thirty patients without aphasia. During scanning, patients closed their eyes and were kept free from any stimulation. X-CT revealed abnormal low density in Broca's area, including cortex and subcortex in the anterior region to Sylvian fissure in three patients with aphasia. In the other five patients with aphasia X-CT showed no abnormal low density in Broca's area, but showed abnormal findings in the basal ganglionic region and subcortex. PET study revealed reduction of rCBF and rCMRO2 in Broca's area in all cases with Broca's aphasia.
CBF and CMRO2 of Broca's area of aphasic patients were compared to those of non aphasic patients to obtain the symptomatic threshold in rCBF and rCMRO2. The values of symptomatic threshold were 20-27m1/l00g/min in rCBF and 2.0ml/100g/min in rCMRO2. The symptomatic threshold differs from the threshold for development of abnormal low density on X-CT, therefore, the measurements of cerebral blood flow and metabolism were useful to study responsible region for aphasia.
