Moya-moya disease: clinical and pathological report of a case with associated myopathy.

A British born white man, age 51 years, presented with cerebrovascular insuffciency, and was found radiologically to have moya-moya disease. He also suffered from a let onset type of progressive myopathy. Five months after the first signs of cerebrovascular disease he died of massive cerebellar infarction. At necropsy the brain showed multiple old and recent infarctions. The anterior cerebral, middle cerebral, and posterior communicating arteries showed segments of narrowing and occlusion by delicate connective tissue, with marked thickening and folding of the elastic lamina. Many dilated thin-walled vessels without a muscle layer and with a poorly formed elastic lamina were present in the subarachnoid space, these probably being newly formed collateral vessels. The cause of the occlusive lesions affecting the cerebral arteries is not known but the morphological appearances do not fall within any known aetiology. It seems that moya-moya disease could be regarded as a distinct entity.