Transtentorial herniation with posterior cerebral artery territory infarction. A new mechanism of the syndrome of alexia without agraphia.

A 39-year-old male developed a right homonymous hemianopsia and alexia without agraphia following emergency surgery for hemorrhage into a left frontal tumor. A computerized tomographic (CT) scan demonstrated low density areas in the left frontal region and in the territory of the left posterior cerebral artery. The alexia without agraphia syndrome appeared to result from compression of the left posterior cerebral artery by a transtentorial pressure cone, a mechanism not previously reported in this syndrome. The behavioral investigation confirmed the diagnosis and replicated recent findings related to the syndrome of alexia without agraphia.