Pre- and postnatal MRI of the fetus with complex intracranial vascular malformation

Intracranial vascular malformations (IVM) on the whole occur in neonates very rarely. In such cases of IVM two different kinds can and must be discerned: (1) dural arteriovenous shunts (DAVS) and (2) vein of Galen aneurysmal malformations (VGAM). The latter seem to represent the majority of IVM of newborns. Several classifications are known for both types. Mortality of neonates and babies due to DAVS exceeds the average mortality from DAVS in adults. VGAM and DAVS can be diagnosed by prenatal ultrasonography only when the vessels behind the shunt are vasodilated because of the increasing flow stress. For that reason VGAM and DAVS are generally not recognized before the last trimenon or even postnatally. The prognosis of an IVM is influenced by the shunt capacity and its resulting cardiac stress as well as by the child's age. To plan the mostly interventional therapy, postnatal angiography (DSA) and MRI are employed and to an increasing extent also prenatal MRI examinations. We describe the case of a very complex IVM, the full dimensions of which could only be discerned by using pre- and postnatal MRI supplementary to the ultrasonography. Besides DAVS, flows from the pericallosal arteries as well as from the thalamic branches had to be considered. As a consequence DAVS and in addition VGAM existed in parallel. (orig.)