[Totally thrombosed large arteriovenous malformation--a case report].

A totally thrombosed large arteriovenous malformation (AVM) which operated as an intracranial space occupying lesion was presented. The patient was a 24-year-old woman who had had frequent attacks of loss of consciousness since the age of 13 years and had been on anticonvulsant medication at the psychiatric department of our hospital. She was referred to our clinic with bitemporal girdle pain, nausea and vomiting. Neurological examination revealed right homonymous hemianopsia, sensory aphasia and choked discs in both ocular fundi. Computed tomogram demonstrated a well defined large high density area with mottled calcification in rostromedial part of the left occipital lobe. The midline structures were displaced to the right side with deformity of the lateral ventricles. Left carotid angiogram showed upward displacement of M2 portion of the left middle cerebral artery. Fine vessels were observed as a capillary blush at the distal part of the pericallosal artery. Teratoma or calcified glioma was suspected preoperatively. But surgery revealed that the large mass was a totally thrombosed AVM. Possible mechanisms for the spontaneous enlargement of the thrombosed AVM were discussed. Cases of totally thrombosed AVM causing displacement of the midline structures or deformity of the ventricles without massive hematoma or disturbance of cerebrospinal fluid circulation have not yet been reported.