Cerebral medullary venous malformations. Report of four cases and review of the literature.

Each type of cerebral vascular malformation has its own unique clinical, radiological and pathological features, and a different pattern of natural evolution. With greater awareness and advances in neuroimaging, there is increasing recognition of Cerebral Medullary Venous Malformations (MVM), angiographically characterised by an 'Umbrella' or 'Caput Medusae' appearance. The clinical and radiological features of four patients with angiographically demonstrable features of cerebral medullary venous malformations, seen in our departments are presented to illustrate the features of cerebral MVMs. Three patients have been managed conservatively and one has been treated with stereotactic radiosurgery. The literature on cerebral MVMs has been reviewed and presented in this paper. It appears that most are benign and even in those cases where there has been a haemorrhage the outcome seems to be much better than with arteriovenous malformations. The rationale behind radiosurgical treatment is discussed. Before embarking upon any form of interventional therapy the natural course of these lesions should be considered.