Posterior fossa venous anomaly and ipsilateral acoustic neuroma: two cases.

The association of an acoustic neuroma with an ipsilateral venous anomaly or angioma is reported in two patients. In the first, the venous angioma was situated low in the posterior fossa, and was of no significance surgically. In the second, the angioma was strongly attached to the capsule of the tumour. On MRI and angiography the lesion appeared as a large draining vein, encircling the tumour. At operation, extensive dissection of the angioma from the neuroma appeared necessary to prevent venous infarction of the brain stem.