[A case of cerebral infarction due to dissection in a branch of the middle cerebral artery].

A 65-year-old man developed left drop hand, dysarthria and emotional incontinence. Brain CT and MRI revealed multiple cerebral infarctions in the cortex and subcortical white matter of the right temporal and parietal lobes which were in the distribution of the right middle cerebral artery. Cerebral angiography disclosed segmental narrowing (string sign) and two pseudoaneurysms in the right angular artery which were diagnosed as dissecting aneurysm of a branch of the middle cerebral artery. In this case, cerebral angiography was more useful than MRI in diagnosis of dissecting aneurysm of a branch of the middle cerebral artery. This was a very rare case of dissecting aneurysm of the middle cerebral artery localized in one of its branches.