[Unilateral development of moyamoya vessels after contralateral cervical internal carotid artery occlusion. Case report].

A 41-year-old female suffered transient ischemic attack. Cerebral angiography revealed occlusion of the left internal carotid artery at the cervical portion and collateral pathways consisting of transpial anastomosis and parenchymal anastomosis from the posterior circulation. Five years later, the second angiography was carried out. Left carotid angiography revealed appearance of transdural anastomosis from the middle meningeal artery and the anterior ethmoidal artery. Right carotid angiography revealed severe stenosis at the carotid fork with moyamoya vessels. Bilateral encephalomyo-arterio-synangiosis was performed for revascularization. Postoperative bilateral carotid angiograms revealed good neovascularization on both sides. In typical moyamoya disease, occlusive change of the carotid fork with moyamoya vessels appeared symmetrically and simultaneously on both sides. Although this case is not a typical moyamoya disease, its pathogenesis is quite similar to that of moyamoya disease.