Vascular malformations of the posterior fossa including the tentorial hiatus

Arteriovenous malformations of the brain: a teratologic challenge

Congenital arteriovenous malformations of the brain are lesions which are well-known to neurologists and neurosurgeons but are puzzling to teratologists because they occur sporadically and are unassociated with congenital malformations outside the central nervous system. They are recommended to teratologists as a field of etiologic and pathogenetic research.

Venous hemodynamics of arteriovenous meningeal fistulas in the posterior cranial fossa

The etiology of arteriovenous meningeal fistulas (AVMFs) of the posterior fossa often remains unclear. Analyses of three personal cases, however, suggest a change in venous hemodynamics due to a primary lesion, the cases being of sinus thrombosis, intracerebral abscess with oedema and arteriovenous malformation. It is suggested that increase of venous pressure in the posterior fossa leads to increased drainage and, consequently, to dilatation of infratentorial veins and of meningeal branches of the external carotid and vertebral artery. Clinical findings and anatomical facts underlying AVMF lesions tend to confirm the view that the concept of a congenital malformation decompensating with age cannot be upheld for all AVMFs, especially when located in the posterior fossa and when clinical symptoms arise in middle age. It is proposed that a pressure activated mechanism of growth results in widening of normally insignificantly small dural vessels.

Varied CT appearance of aneurysms of the vein of Galen in infancy

An aneurysm of the vein of Galen can have a varied CT appearance in infancy. The classical picture is a spherical posterior third ventricular mass with the density of circulating blood contiguous with a dilated straight sinus and with uniform contrast enhancement. With varying degrees of thrombosis of the aneurysm which may occur in late infancy, the mass can change in density and the dilated straight sinus disappear. With total thrombosis, a precontrast hyperdense rim develops with a low density. The rim enhances but the low density center does not change with contrast infusion. Our experience in three patients with this spectrum of CT findings will be demonstrated and correlated with clinical findings and angiography.

Hypervascular cavernous angioma at angiography

Arteriovenous malformations usually do not present any diagnostic difficulty on the angiograms. However, small cryptic and cavernous angiomas cannot be demonstrated directly by arteriography because of either sluggish circulation or thrombosis. The present communication documents a relatively rare case of histologically proven cavernous angioma with a hypervascular pattern on the arteriogram.

Persistent embryonic veins in arteriovenous malformations of the posterior fossa

In the arteriovenous malformations of the posterior fossa the arterial feeders and the dural venous sinuses can be identified in anatomical terminology. The arterialised veins which do not conform to adult anatomical descriptions represent the persistent embryonic veins of the metencephalic and myelencephalic segments of the developing brain. These can be identified and described when related to the embryo.