Does moyamoya disease cause subarachnoid hemorrhage?

The majority of patients with intracranial hemorrhage associated with moyamoya disease have been described as having subarachnoid hemorrhage (SAH), but it seems doubtful that moyamoya disease causes primary SAH. Computerized tomography (CT) has revealed that most of the hemorrhage found in cases of moyamoya disease is intracerebral or intraventricular. The authors have reviewed 54 cases of intracranial hemorrhage confirmed by CT, including nine of their own, and found that in all but one the bleeding was intracerebral or intraventricular. The single case of SAH was due to rupture of a saccular aneurysm associated with moyamoya disease. It may be concluded from these results that moyamoya disease does not cause primary SAH per se.