Ahead of Print: Safe Resection of Arteriovenous Malformations in Eloquent Motor Areas Aided by Functional Imaging and Intraoperative Monitoring
BACKGROUND: Arteriovenous malformations (AVMs) proximal to motor cortical areas or motor projection systems are challenging to manage due to the risk of severe sensory and motor impairment. Surgical indication in these cases therefore remains controversial.
OBJECTIVE: To propose a standardized approach for centrally situated AVMs, based on functional imaging and intraoperative electrophysiological evaluation.
METHODS: We conducted a retrospective analysis of 15 patients who underwent surgical treatment for AVMs in motor cortical areas or proximal to motor projections. Preoperative assessment included fMRI and 3D-tractography. Operations were performed under continuous electrophysiological monitoring aided by direct brain stimulation. We identified critical bloody supply to the motor areas by temporary occluding the feeding vessels under electrophysiological monitorization. Clinical outcome was evaluated using the modified Rankin Scale.
RESULTS: Total resection was achieved in 12 cases, while electrophysiology limited total extirpation in 3 subjects. A significant reduction of motor evoked potentials (MEPs) by up to 15% of the initial values was associated with good recovery of motor function; by contrast, the disappearance of potentials correlated with long-term impairment. The mean follow-up time was 13 months, and clinical assessments revealed overall functional improvement (p<0.05). After surgery, 11 patients were asymptomatic or presented only with minor neurological deficits.
CONCLUSION: Surgical resection of AVMs in eloquent motor areas can be considered a safe option for selected cases when performed in conjunction with a detailed functional assessment. Possible selection criteria for surgical treatment are discussed in light of the presented clinical data.