Developmental venous anomalies of the posterior fossa with transpontine drainage: report of 3 cases.

Developmental venous anomalies (DVA) are considered as variant patterns of cerebral venous drainage. Although generally not rare in the cerebellum, DVA of the brain stem or of the cerebellum with drainage through the brain stem are exceptional findings. Because it is not clear whether DVA may sometimes be of clinical significance, we try to correlate the clinical findings of the patients with the course of the variant vessels. We reviewed the literature and report three additional cases. All patients were examined by MRI and digital subtraction angiography. In particular, we discuss the drainage route as compared with the established patterns of posterior fossa blood drainage, which is directed to the dural sinuses, the petrosal vein or the vein of Galen. In one of our patients suffering from trigeminal neuralgia, the close topical relation of the DVA and the trigeminal nucleus and trigeminal nerve entry zone suggests a causal relationship. In a second case the brain stem symptoms were due to haemorrhage of a concomitant cavernoma. It remains unclear if the occurrence of dysarthria and dysaesthesia in the third patient with brain stem DVA was purely coincidental. The only clinical symptom directly attributable to a DVA with transpontine drainage in our series was trigeminal neuralgia.