Vascular Malformations of the Posterior Fossa: Clinical Features, Treatment, and Outcomes

Vascular malformations affecting the cerebral hemispheres are a relatively common clinical entity. In contrast, vascular malformations of the posterior fossa are rare, and there are few documented series involving a large number of patients. Our experience with 93 patients encountered at The Johns Hopkins Hospital is reported. The records of all patients admitted with a radiologically verified diagnosis of posterior circulation vascular malformation from January 1986 through December 2000 were retrospectively reviewed. There were a total of 712 cases of vascular malformations. Of these, 93 cases localized to the posterior fossa (13%). The pathologic findings were consistent with an arteriovenous malformation in 38 patients (41%), cavernous malformation in 20 patients (22%), venous malformation (VM) in 17 patients (18%), and dural arteriovenous fistula in 18 patients (19%). All patients, except for those with VMs, were treated by means of surgery, radiosurgery, or neuroradiologic intervention. Sixty-six percent of patients showed excellent recovery, with 18% more exhibiting only mild neurologic deficits. The overall morbidity in this series was 10.5%, with a mortality rate of 5.3%. Management of vascular malformations in the posterior fossa can pose significant problems. In our experience, patients who are symptomatic, have a prior history of hemorrhage, and are at increased risk for future bleeds are best treated by surgery ± preoperative embolization. On the other hand, patients who are asymptomatic or who harbor small lesions in relatively inaccessible areas benefit the most from radiosurgery. This approach has led to excellent clinical outcomes, with the majority of patients remaining neurologically intact.