Posterior fossa arteriovenous malformations: Significance of higher incidence of bleeding and hydrocephalus

• More than half of patients with ruptured pfAVM presented hydrocephalus.
• PfAVM have statistically significant higher need of EVD and permanent shunt than spAVM.
• The usual hemorrhagic presentation and intraventricular invasion may be the cause.
• Despite initial high mortality, survivors have good outcome in 70% of cases.

ObjectiveHydrocephalus associated with different types of intracranial arteriovenous malformations (AVMs) has been scarcely studied. In the present report we investigate this association with posterior fossa AVMs (pfAVMs). We hypothesized that there is an increased risk of hydrocephalus and required permanent cerebrospinal fluid (CSF) shunt in patients with pfAVMs that may be linked to the increased risk of bleeding of these lesions. We also review the factors associated with this increased risk of hemorrhagic presentation and we assess how it affects management strategies and functional outcomes in these patients.MethodsOut of a prospective registry of 374 patients with brain AVMs diagnosed in our center from 1993 to 2013, 60 (16%) had a pfAVM. We described these patients’ demographics, their AVM characteristics, clinical presentation, and hydrocephalus incidence and compared the results with those of the supratentorial AVM (spAVM) patients recorded during the same period.ResultsOut of the 60 patients with pfAVMs, 10 (16.7%) presented AVMs located in the brainstem. Hemorrhagic presentation (49/60; 82%) was significantly higher in pfAVMs than in spAVMs (122/314; 38.8%; p < 0.05). Hydrocephalus was a common complication in pfAVM patients who had a statistically significant higher need for both temporary external ventricular drain (EVD) (6.7 vs. 20%; p < 0.05) and permanent CSF shunts (3.5 vs. 20%; p < 0.05). The initial mortality was high (12/60; 20.3%) and half of these patients died before any treatment option could be offered. However, out of those who survived, 70% (42/60) had already shown good clinical outcome at the 6-month follow-up.ConclusionsHemorrhagic presentation and hydrocephalus have a higher incidence in pfAVM patients, which initially results in more neurological deficits and an elevated mortality even before receiving any treatment. However, a large number of survivors present good functional outcomes at early follow-up, justifying an aggressive management strategy with microsurgery as the first treatment option in most cases, and radiosurgery as an alternative, especially in brainstem AVMs.