Moyamoya disease associated with Graves disease: special considerations regarding clinical significance and management

Object. In moyamoya disease (MMD), ischemic events are usually precipitated by activities associated with hyperventilation or physical strain. The authors report on four patients with a rare combination of Graves disease-associated thyrotoxicosis and MMD, whose cerebrovascular ischemic events occurred while in a thyrotoxic state. The clinical correlation between MMD and Graves' thyrotoxicosis, and outcome after surgical intervention are described. Methods. Four Young women, ages 22 to 25 years, presented with profound cerebrovascular ischemic accidents. They had clinical and radiological features consistent with the diagnosis of MMD and were in the active thyrotoxic state of Graves disease. To prevent a future ischemic event, patients underwent superficial temporal artery-middle cerebral artery anastomosis combined with encephalornyosynangiosis or encephaloduroarteriosynangiosis after normalization of their hormonal conditions. All patients have been neurologically stable since revascularization procedures and lead a normal daily life. In patients with MMD, cerebrovascular ischemic events may be precipitated by thyrotoxicosis. One possible pathomechanism of cerebrovascular ischemic aggravation in the thyrotoxic state may be a hemodynamic compromise induced by an excessive increase in the cerebral metabolism and oxygen demand over the compensation of the cerebral blood flow deficit through collateral supply in MMD. Conclusions. Surgical revascularization after optimal control of thyrotoxicosis is thought to be an appropriate treatment in patients with MMD concurrent with Graves disease for the prevention of further ischemic events, especially in those with impaired cerebral perfusion and cerebral ischemic symptoms.