Abstract
A 59-year-old woman with untreated hypertension, dyslipidemia and diabetes was examined for weakness affecting the left side of the body. Cerebral infarction due to occlusion of the right distal middle cerebral artery branch was diagnosed and she was thus hospitalized. At the initial visit, her symptoms had shown improvement, and there were no neurological deficits. After admission, however, she experienced gradual progression of paralysis of the left upper and lower extremities, and magnetic resonance imaging revealed infarction in the entire territory of the perforating branch at the M1 segment of the right middle cerebral artery. Magnetic resonance angiography on the 14th hospital day showed the presence of a right accessory middle cerebral artery for the first time, and severe stenosis at the origin of the middle cerebral artery main stem. An accessory middle cerebral artery is a rare vascular variation with an incidence of 0.3% to 4%. In the present case, as the accessory middle cerebral artery was judged to be occluded at the distal branch of the middle cerebral artery main stem due to occlusion of the middle cerebral artery main stem, the occluded vessel was not consistent with the infarcted region, making the pathological condition difficult to diagnose. If occluded vessels are not consistent with infarcted regions, it is important to diagnose and treat them while keeping the possible presence of vascular variations in mind.
