Internal cerebral veins varix due to midline arteriovenous malformation: how much is the risk of bleeding?

Abstract

We report a case of 40-year-old sportsman admitted to our department for a generalized seizure associated with bladder and bowel incontinence occurred during exercise. The patient quickly regained consciousness without postcritical deficits. Neurological examination appeared completely normal. A head computer tomography (CT) scan showed a midline arteriovenous malformation (AVM) without the evidence of bleeding (Fig. 1a, b). A digital subtraction angiography revealed a dysplastic nidus fed by branches of bilateral internal–external carotid and vertebrobasilar arteries, and draining both in the superficial and deep venous system, which showed varicose dilatation with Galen’s vein stenosis (Fig. 1c–g). Cerebral varix is defined as an ectasia which doubles vein diameter. It can be due to an arteriovenous shunt and appears more common in patients with direct fistulas, than in cerebral AVM with dysplastic nidi [1]. Differently from those associated with Galen’s vein fistulae, huge intracranial varix associated with cerebral AVMs were seldom reported. Headache, bruit, focal mass effect and hydrocephalus are common presentation symptoms [2]. Intracranial haemorrhage has been instead less often reported at clinical onset [3]. In the most of the cases of giant varix, direct arteriovenous communications in the context of nidus were observed, especially between feeding arteries and the varicose veins [4]. This discrete angiographic finding separate these vascular malformations from the classical and more common AVMs in which an abnormal vascular network is identified between the arterial feeders and draining veins [4]. Venous hypertension with retrograde drainage often results in focal neurological deficits and seizures [1]. Although it is commonly assumed that venous ectasia increases the bleeding risk, varix haemorrhagic presentation has been rarely reported [4]. It is may be due to the progressive thickening of the arterialized veins wall, with intimal proliferation of synthetic smoothmuscle cells and disappearance of the internal elastic lamina, that make arterialized veins not greatly prone to rupture [1, 4]. On the other hand, instead, the presence of venous varix on the draining veins has been recognized as a factor increasing the risk of haemorrhage in dural arteriovenous fistulae [5]. In the case reported here, the presence of multiple feeders causing high flow shunt rate, direct drainage in a cisternal venous system, and an impaired venous outlet due to the Galen’s vein stenosis, may have contributed to the varix formation. Prolonged sporting activity, instead, has not been a factor influencing AVM rupture.