Teaching Case

A 17-year-old female patient, while in complete well-being, suddenly fell down to the ground unconscious and was transported to the emergency room. Physical examination was performed noting drowsiness, ataxia, vertigo and headache. These symptoms were suspicious for a stroke.

An emergency non-contrast CT documented an area of haemorrhage in the right cerebellum of 5 x 4 cm responsible of a mass effect on the brainstem and the fourth ventricle, associated with oedema and controlateral shift. After a CT angiography, we diagnosed a cerebellar AVM of 3.6 cm in the previous haemorrhagic area. Thus, an emergency craniectomy was performed to reduce the intracranial pressure through a CSF drainage. Non-contrast CTs after surgery showed a progressive reduction of the haemorrhagic and oedematous area, associated with a partial clinical resolution, despite the persisting AVM.

AVMs are an abnormal tangle of arteries directly connected to veins without an intervening capillary network, that typically appear as a jumble of enlarged vessels without mass effect, in 90% of the cases in the supratentorial region. AVMs of the posterior fossa are relatively rare comprising only between 10 and 15 % [2]. Patients with posterior fossa AVMs are at increased risk for severe morbidity, mortality due to bleeding or complications related to procedures. Moreover, the annual risk of bleeding (2-3%) may double or even triple in the first year after an initial bleed [1]. Contrast-enhanced CT is the initial diagnostic examination to detect an AVM. MRI can be used to monitor the evolution. Non-contrast CT shows a mixed attenuation lesion, sometimes with evidence of calcification. MR demonstrates flow voids or complex flow patterns, sometimes leading to artefacts in the phase-encoding direction. However, angiography remains the definitive method for evaluation of the vessel anatomy and dynamic flow patterns. At the moment, several treatments are feasible: surgery, radiotherapy or endovascular embolization.
In our case we treated the lesion with an endovascular embolization.
Through a right retrograde transfemoral artery access, the internal carotid arteries and the vertebral arteries were selectively catheterized showing that the right AICA was the main feeding artery. Moreover, PICA was not a collateral of the AVM.
Thus, 6 cc of Glubran were injected in the feeding arteries. Post-procedural control documented the AVM complete exclusion.
MR after 30 days confirmed the complete exclusion of the AVM, with complete shift resolution and reduction of the haemorrhagic component.