[Encapsulated chronic intracerebral hematoma caused by venous angioma of the basal ganglia: a case report].

A case is reported of venous angioma at the right basal ganglia simulating the encapsulated chronic intracerebral hematoma. A 29-year-old man was admitted to our hospital on July 14, 1988 with a two-month history of headache. Neurological examination revealed left homonymous lower quadrantic anopsia. CT scans showed a mosaic high density lesion at the right basal ganglia with extensive adjacent edema. MRI revealed that the high density lesion on CT scans was the combination of a reticulated core of mixed signal intensity with a surrounding rim of decreased signal intensity. The lesion was accompanied with extensive edema. Followed up CT scans showed the transformation of the lesion and ring-shaped enhancement. A right frontotemporal craniotomy was performed on August 9, 1988. After thorough dissection of the sylvian fissure and small corticotomy to the insula, a tough capsule was seen. There was blood in various stages of organization in the capsule. A histological examination gave a diagnosis of venous angioma in the membrane similar to the outer membrane of chronic subdural hematomas. Postoperatively, the patient showed slight left motor weakness, but it gradually improved and he was discharged on foot, on October 19, 1988. There have been a lot of reports about angiographically occult intracranial vascular malformation (AOIVM). But AOIVM at the basal ganglia is rare, and to our knowledge, only 8 cases have been reported. In our case, the presence of adjacent extensive edema, and ring-shaped enhancement on CT scans confused the preoperative diagnosis. Those findings might have been caused by encapsulation. By using CT scans and MRI, a complete and accurate diagnosis was impossible.(ABSTRACT TRUNCATED AT 250 WORDS)