[A successful removal of huge confluence meningioma].

A rare case of huge confluence meningioma with many kinds of venous collaterals is presented. A 58-year-old female was admitted because of severe headache and gait disturbance. An enhanced CT (computerized tomography) scan demonstrated a homogeneous spherical high density mass in the region of the posterior falco-tentorial junction adjacent to the internal occipital crest. Cerebral angiograms showed (1) the occluded confluence sinuum and compensatory venous collaterals, (2) venous drainage through the persistent falcial sinus, which was rare in an adult, from the straight sinus into the superior sagittal sinus (SSS), (3) venous drainage through diploic veins and emissary veins into scalp veins. The tumor including the confluence sinuum was totally removed via a combined bioccipital and suboccipital craniectomy. The confluence sinuum was invaded and occluded by the tumor. The tumor was histologically diagnosed as a fibroblastic meningioma. Post-operative angiogram showed a formation of the new venous channel which is located between the posterior part of the SSS and the lateral part of right transverse sinus. The origin of this new venous pathway was thought to be congenital presence of a "latent" dural venous channel. After ventriculoperitoneal shunting, the patient was discharged without any neurological deficits. A follow-up angiogram one year and two months after discharge showed that the channel become dilated and the venous collaterals seen before surgery disappeared probably due to the change of balance of venous pressure. The venous drainage pattern seemed to become resembling the normal variant type in which the SSS drains into the right transverse sinus, and left sinus was hypoplastic.(ABSTRACT TRUNCATED AT 250 WORDS)