Bidirectional flow of contrast material in middle cerebral artery branches.

Abstract

In 9 out of 24 patients with occlusion or stenosis of the middle cerebral artery, anterograde as well as retrograde flow of contrast material within the same vessel was demonstrated angiographically in one or several branches of the artery. Retrograde filling always occurred via leptomeningeal anastomoses which also contributed to anterograde flow in cases of middle cerebral artery branch occlusion. In other cases with branch stenosis, delayed anterograde flow via the normal pathway, and retrograde flow via leptomeningeal anastomoses, met each other. The phenomenon of bidirectional flow in a cortical branch occurred, for instance, during recanalization and seems not be correlated with an especially unfavorable prognosis for the dependent cerebral tissue. The angiographic criteria for cerebral arterial branch occlusion become questionable in view of the phenomenon of bidirectional flow of contrast material.