Angiographic and embryologic considerations in five cases of middle cerebral artery fenestration.

Five cases of unilateral middle cerebral artery fenestration were observed during the prospective evaluation of 1466 consecutive cerebral angiograms (0.43% of 1170 patients) between January 1999 and July 2001. In each case, an early branching temporopolar artery was seen to arise from the inferior limb of the fenestrated segment. This finding suggests that early branching temporopolar arteries may participate in the formation of middle cerebral artery fenestration by interfering with the normal fetal development of the middle cerebral artery.