Abstract
A patient manifesting transcortical motor aphasia (TCMA) caused by a left frontal subcortical infarction is reported. A low density area was visualized by CT scanning in the white matter anterolateral to the left anterior horn of the lateral ventricle. This site contained fibers between the supplementary motor area (SMA) and the frontal perisylvian speech zone (Broca's area). Freedman et al. demonstrated that the involvement of these fibers was essential for patients with TCMA, and concluded that disconnection between the SMA and Broca's area was causing the TCMA. Recently, some studies for aphasic patients with subcortical lesions showed that cerebral blood flow (CBF) in the cortex is also decreased. These findings suggest that dysfunction of the cortex as well as the subcortical region is responsible for “subcortical aphasia”. In the present case, on the contrary, CBF in the frontal cortex was not so decreased. Therefore, primary dysfunction of the frontal cortex was thought to be negligible and disconnection seemed to be the cause of the TCMA. Our case suggests that a certain subcortical lesion causes aphasic symptoms.
