RESUMO
Intracranial vascular malformations have been classically divided into four groups: arterio-venous malformations (AVMs), cavernous angiomas, venous angiomas and capillary telangiectasias. The AVMs are the best documented of these lesions and are readily characterized with cerebral angiography. The other malformations have previously been rarely diagnosed during life as they are usually not seen on cerebral angiograms. Recently, however, with the use of advanced neuro-imaging techniques these lesions have been increasingly recognized in association with intracranial haemorrhage and epilepsy. Cavernous angiomas, in particular, have a characteristic appearance on MRI scans. This paper will define these "occult" vascular malformations of the brain, their incidence, clinical presentation, natural history and issues related to management. The experience of the Department of Neurosurgery and the Division of Neuro-Radiology at the Victoria General Hospital in Halifax during 1990 will be summarized. Of over 1,200 consecutive cranial MRI scans, 18 cases of cavernous angiomas were encountered. Some of these caused intracerebral haemorrhage and others were seen in patients with complex countered. Some of these caused intracerebral haemorrhage and others were seen in patients with complex partial seizures. A surprising number were multiple and familial in occurrence. These lesions can present in the brain stem or spinal cord thus mimicking multiple sclerosis. The majority of them are asymptomatic and are incidental findings. Venous angiomas are, in fact, hamartomas and rarely lead to symptoms; because they drain normal neural tissue they cannot be sacrificed without risk of significant neurological sequelae. The emerging literature on angiographically occult vascular malformations of the brain will be reviewed (AU)
