Effect of mouth opening on bypass function after combined revascularization for Moyamoya disease.

Moyamoya disease represents a rare steno-occlusive disease of the internal carotid artery (ICA) with a reactive and pathological basal network of collateral vessels. It may lead to ischemic stroke or intracerebral hemorrhage. Treatment options are either direct or indirect revascularization procedures or a combination thereof. Specialized centers report sufficient revascularization in most patients and low complication rates.Between 2005 and 2008, direct extra-intracranial bypass surgery in combination with encephalomyosynangiosis (EMS) was performed in 71 Moyamoya patients at the Mannheim University Medical Center.Following one case of reversible neurological deficits associated with mouth opening, we prospectively evaluated the effect of mouth opening on bypass function in this patient and four further consecutive patients by digital subtraction angiography.Three out of five patients showed alterations in bypass patency upon mouth opening. The obstruction was located at the junction of the bypass and the temporal muscle. Two temporary occlusions and one case of decreased flow were observed. One patient demonstrated reversible hemiparesis and aphasia.