CEREBRAL VENOUS ANGIOMAS - 12 CASES AND A REVIEW OF THE LITERATURE

Cerebral venous angiomas (CVAs) are made up of veins with abnormal structure : thick walls, lumens dilated of irregular calibre that converge radially towards a wide draining vein. The arteries are normal. The veins are separated by a normal nervous tissue. The malformation is thought to develop as a compensatory venous drainage consecutive to the occlusion, or lack of development, of one or several transcerebral veins during the formation of the mature venous system. Together with arteriovenous angiomas, capillary telangiectasias and cavernous angiomas, CVAs belong to the vascular angiomatous malformations, also called hamartomas. The present study is based on 12 cases collected between 1984 and 1989, all explored by CT and angiography, and by MRI in 2 cases. The diagnosis therefore was neuroradiological, except in 1 case where it was obtained by neuropathological examination. The malformation was supratentorial in 10 cases and cerebellar in 2 cases. Most CVAs were discovered in patients whose symptoms could hardly be attributed to these malformations and consequently were termed asymptomatic (6 cases). Two cases were found in subjects with generalized epileptic seizures without clear-cut relationship with the angioma ; 4 cases were revealed by haemorrhages : subarachnoidal haemorrhage in 2 cases and supratentorial intraparenchymatous haematoma in 1 case. These 3 cases had a spontaneously favourable outcome after a follow-up of several years. One patient with a cerebellar hematoma died postoperatively of edematous infarction of the cerebellum. One of these patients had two symmetrical CVAs, one in each cerebral hemispher (multiple venous angiomas), and in another patient the CVA was probably associated with a cavernous angioma. We have also reviewed 247 cases reported between 1961 and 1989. The frequency of CVA is diversely evaluated, and the results of series with autopsies are extremely varied, the proportion of CVAs among vascular angiomatous malformations ranging from 16 to 63 p. cent in recent studies. The first angiographic description dates back to 1967. Recent publications are more numerous, and because the CT image of the malformation is better and its detection easier the relative rarity of CVAs has become questionable. Sixty-nine percent of CVAs are supratentorial and mostly located in the frontal lobe ; 80 p. cent of infratentorial CVAs are located in the cerebellum. The malformations are detected in a wide variety of circumstances. In 40 p. cent of the cases they are found by chance while investigating for symptoms with doubtful clinico-pathological correlations (e.g. headaches and loss of consciousness); 24 p. cent are discovered in patients with epilepsy, but in 50 p. cent of these the cause-effect relationship with CVA can be questioned. In 20 p. cent of the cases the malformation is blamed for focal signs in the absence of haemorrhage. Finally, 16 p. cent of CVAs are complicated by an intracranial haemorrhage, usually an intraparenchymatous haematoma most frequently located in the posterior fossa. The diagnosis of CVA is generally based on neuroradiological findings. Contrast-enhanced CT images are suggestive in most cases, showing a continuous or dotted line corresponding to the draining vein, without mass effect or oedema. In 90 p. cent of the cases angiography shows a typical and pathognomonic << medusa head >> with a superficial or deep drainage and a normal arterial phase. Angiographically silent CVAs are always complicated by hemorrhage, thrombosis or calcifications. MRI is almost sensitive as angiography, with a stellar morphological image and a haemodynamic image of malformation with slow and lamellar blood flow. In the majority of cases, the CT and MRI results are sufficiently suggestive to assert the diagnosis, and in future, angiography will become an exceptional procedure. The classical benignity of CVA must be tempered by its globally fairly severe outcome, as shown by focal signs and by the fact that haemorrhages are not uncommon. However, these haemorrhages are usually circumscribed and of favourable prognosis. They seldom are recurrent. Surgery is indicated in cases where the hemorrhages, notably in the posterior fossa, are life-threatening. The standard procedure is to drain the haematoma and not to remove the CVA, as this would expose to the risk of postoperative venous infarction.