Spontaneous occlusion of an intracranial arteriovenous malformation.

The case of a 2-month-old girl is described in whom an arteriovenous malformation (AVM) was observed in the paramedial region of the right cerebral hemisphere associated with an arachnoid cyst in the right fronto-parieto-temporo-occipital region. The only treatment was evacuation of the arachnoid cyst by trephination. When the child was 3 years old, images of the AVM were not found although all the intracranial vessels were angiographically explored. It is considered that the reduced pressure in the right cranial cavity due to the drainage of the arachnoid cyst may contribute to the occlusion of the AVM by causing a slight displacement of the intracranial structures towards the side of the drained cyst.