Neurosurgical advances in the treatment of moyamoya disease.

BACKGROUND AND PURPOSE Moyamoya disease is characterized by chronic stenoocclusive vasculopathy involving the distal supraclinoid internal carotid arteries and presents with ischemic or hemorrhagic symptoms. We review advances in the understanding and management of moyamoya disease. SUMMARY OF REVIEW Cerebral revascularization, either direct or indirect, is the cornerstone of treatment for moyamoya disease. Recent advances have been made in understanding the molecular biology and pathophysiology of moyamoya disease, and new genetic mutations and deletions have been identified. Imaging for moyamoya disease is also rapidly improving with new sequences of MRI and better methods of assessing ischemia and cerebrovascular reserve. Positron emission tomography has emerged as an important tool to measure cerebrovascular reserve. Novel surgical techniques assess patency and ischemia during superficial temporal to middle cerebral artery bypass, including indocyanine green videoangiography to evaluate anastomosis patency, and various methods to monitor intraoperative blood flow. Newer methods of indirect revascularization have been described with placement of more tissues supplied by the external carotid artery on the brain surface. Postoperative hyperperfusion to the chronically ischemic brain tissue is a recently identified causative factor of complications. Interestingly, complications from hyperperfusion mimic those caused by ischemia, although they have different treatments, making the role of postoperative blood flow assessment important in distinguishing between the two. Awareness has also increased that even asymptomatic patients can experience significant cognitive decline attributable to chronic ischemia. Whether this reverts after successful revascularization requires investigation. CONCLUSIONS Surgical revascularization with direct, indirect, and combined methods remains the preferred procedure for patients with moyamoya disease.