Late-onset acid maltase deficiency associated with intracranial aneurysm.

The autopsy findings in a patient with late-onset acid maltase deficiency who died following rupture of a basilar artery aneurysm are reported. The patient developed muscular weakness and wasting at the age of 20 years and died 9 years later after suddenly falling into a coma. At autopsy a giant fusiform aneurysm was found in the basilar artery which had ruptured at the base of the pons, leading to a large haematoma in the pons. The cerebral arteries and arterioles showed extensive vacuolar degeneration of smooth muscle cells in the media. It is suggested that the aneurysm was induced by fragility of the arterial wall due to this smooth muscle change.