Progressive lacunar infarction with demonstrated patency of the middle cerebral artery.

Two cases of progressive hemiplegia were closely followed by daily clinical examination. In both, the CT scan and CSF were normal on admission. In both, objective aggravation occurred in three or more steps over four days, progressing from minor finger clumsiness to total paralysis of the arm. In both cases a second CT scan a day after appearance of hemiplegia demonstrated a lacune in the corona radiata just above the internal capsule. In one case an intravenous digital subtraction angiogram demonstrated patency of the middle cerebral artery during the course of the progression. In the other case, serial study with transcranial Doppler ultrasound documented the continued patency of the middle cerebral artery. These two cases demonstrate that it is not necessary to postulate transient occlusion of the middle cerebral artery as an essential mechanism for progressive lacunar infarction.