It is generally conceded that cerebral vascular disease reaches its peak incidence in the later decades of life. Although cerebral embolism and primary subarachnoid hemorrhage are more evenly distributed among the various age groups, cerebral thrombosis and intracerebral hemorrhage occur most frequently in the fifth to eighth decades. In a tabulation of age incidence in 245 necropsied cases of cerebral vascular lesions, Aring and Merritt1 indicate that 4% of the cases of intracerebral hemorrhage and only 1% of the cases of cerebral thrombosis occurred in persons under the age of 40. It must be remembered that these figures relate to necropsied cases and are probably lower than those which might obtain in a clinical series.
Accordingly, when the apoplectic onset of a neurologic disorder occurs in a normotensive person under the age of 40, the etiologic diagnosis becomes a matter of more than ordinary interest to the neurologist. The