Eighty-six stroke patients which was comprised of 63 cases of cerebral infarction and 23 cases of cerebral hemorrhage with speech disturbance and sign of dominant hemispheric lesion in chronic stage were investigated using the Standard Language Test for Aphasia, EEG including photic stimulation and cranial computed tomography (CCT). The purpose of this study was to demonstrate the differences between cerebral infarction and cerebral hemorrhage as seen in aphasic symptoms, EEG and CCT findings and also investigate the possible causes of those differences.
In cerebral infarction, aphasic symptoms were variable in each case according to its type and severity. Although in cerebral hemorrhage, mild aphasia such as amnestic aphasia and mild Broca's aphasia were more commonly observed.
In the cases of cerebral infarction, EEG findings were also variable and tended to show mild to moderate abnormality and low voltage in nature. Many of the cerebral hemorrhagics indicated severely abnormal EEG which consisted of high voltage slow wave and defective photic driving on both sides.
In cerebral infarction, CCT revealed that distribution of low density area was again variable and was located mainly in the cortex. Although in the cases of cerearal hemorrhage, the low density area had a tendency to be confined to the basal ganglia and /or to the internal capsule.
Some cases of cerebral infarction with wide spread low density area including more than three cerebral lobes showed normal to slightly abnormal EEG. In contrast with this, severely abnormal EEGs were rather common among the cases of cerebral hemorrhage with low density area which tended to be strictly confined to the basal ganglia and / or the internal capsule.
From these results, the common site of the lesion was considered to be a major factor in the difference between cerebral infarction and cerebral hemorrhage as seen in aphasic symptoms, EEG and CCT findings. Namely, many cases of cerebral infarction have lesions in the cerebral cortex which produce aphasic symptoms of various kinds and affected voltage generator which is manifested by a low voltage pattern of EEG. In the cases of cerebral hemorrhage, common lesions were found in the deep structure involving the thalamocortical projection, which bring deafferentiation effect on EEG which is characterized by a high voltage slow wave.
