運動失調性構音障害における右第３前頭回脚部（右Ｂｒｏｃａ中枢）病変の役割

Abstract

We observed ataxic dysarthria in one of two right-handed patients who had a localized lesion due to cerebral infarction in the posterior part of the inferior frontal gyrus in the right hemisphere (right Broca's area). Patient 1, a forty-two-year-old right handed female suddenly started having dysarthria. Eval uation of her speech revealed that she had typical ataxic dysarthria. CT scan and NMR showed separate lesions in the right Broca's area and in the right upper cerebellum. Patient 2, a sixty-one-year-old right-handed male suddenly started having left hemiparseis. He showed no speech disturbance in clinical examination. CT scan and NMR showed independent lesions in the right Broca's area and in the left middle frontal gyrus. As observed in patient 2, a lesion localized in the right Broca's area doesn't always cause dysarthria, while combined lesions in the right Broca's area and in the right upper cerebellum appear to cause ataxic speech, as seen in patient 1. These findings suggest that the right Broca's area plays a certain role in articulatory function. This assumption is supported by the anatomical fact that the frontal lobe and cerebellum have firm connections.