A Large Middle Cerebral Aneurysm presenting as a Bizarre Vascular Malformation

Abstract

Aneurysms of the cerebral vessels usually remain asymptomatic until rupture, but some may become very large and present as a mass lesion (Case Records of Massachusetts General Hospital, 1963; Anderson, 1885; Garvey, 1934; Guidetti, 1964; Sadik, 1965; Stenvers, 1963). This case, an extremely large (8·0×5·5×5·5 cm) aneurysm arising at the bifurcation of the left middle cerebral artery, presented as a mass lesion and is reported because of an unusual radiographic appearance which resembled an arteriovenous malformation. A 58-year-old male high-school teacher was well until three months prior to admission when he began experiencing increasingly severe generalised headaches. Two weeks before admission he suddenly developed difficulty in naming objects and mild confusion which initially improved and remained static. On examination the positive physical findings were confined to the nervous system and consisted of a marked dysnomia, mild dyspraxia, dyscalculia, and finger agnosia. There was no motor or sensory deficit and reflexes were symmetrically active. There were no pathological reflexes. A lumbar puncture revealed an elevated pressure of 230 mm of CSF with a protein of 200 mg per cent. Both a 203Hg brain scan and an EEG showed evidence of a left fronto-parietal lesion and a Wada test demonstrated left cerebral dominance for speech. Skull films showed the pineal to be shifted 5 mm to the right of the midline and there was slight demineralisation of the dorsum suggesting increased intracranial pressure.