Cortical reorganization of motor functional areas in cerebral arteriovenous malformations.

Cerebral arteriovenous malformations (AVM) are congenital malformations that may grow in functional areas such as the primary motor cortex, but do not lead to motor deficits unless they rupture. We attempted to determine whether cortical reorganization was present in patients with AVM. We identified 22 patients with AVM who undergone had motor functional MRI (fMRI) evaluation. Patients were categorized according to AVM location: Group 1-away from motor areas (13 patients, 59.1%); Group 2-adjacent to motor areas (3 patients, 13.6%); and Group 3-overlying motor areas (6 patients, 27.3%). Groups 2 and 3 were compared to Group 1. In Group 3, six of six patients demonstrated cortical reorganisation (p=0.00037), and the four who underwent AVM removal did not sustain new neurological deficits. In Groups 1 and 2 no patient showed cortical reorganisation. Evidence of cortical reorganisation in patients with AVM overlying eloquent areas suggests that resection of these AVM may be possible with acceptable neurological deficits.