Staged radiosurgery for extra-large cerebral arteriovenous malformations: method, implementation, and results

Area of Science:

• Neurosurgery
• Radiology
• Neurology

Background:

• Management of large cerebral arteriovenous malformations (AVMs) presents significant challenges.
• Small- to medium-sized AVMs are effectively treated with radiosurgery.
• Extra-large AVMs require innovative treatment strategies.

Purpose of the Study:

• To evaluate the effectiveness and safety of preplanned staged radiosurgery for extra-large cerebral AVMs.
• To assess clinical outcomes and AVM obliteration rates.
• To determine the feasibility of staged radiosurgery for AVMs exceeding 40 ml in volume.

Main Methods:

• Six patients with extra-large AVMs (>40 ml nidus volume) were treated with preplanned staged Gamma Knife radiosurgery (GKS).
• Staged radiosurgery involved two sessions with a mean interval of 6.9 months.
• Prescribed marginal doses ranged from 16 to 18.6 Gy per stage, with an expected total dose of 17-19 Gy.

Main Results:

• Patients experienced clinical improvement, including headache relief and reduced seizure frequency.
• Significant nidus regression was observed on follow-up MR imaging in all patients.
• Complete nidus obliteration was confirmed by angiography in two patients at 45 and 60 months post-treatment.

Conclusions:

• Staged radiosurgery is a viable strategy for treating extra-large cerebral AVMs.
• Longer obliteration times are expected compared to smaller AVMs.
• Preliminary findings suggest clinical insignificance of post-radiosurgery T2 changes, warranting longer follow-up for safety confirmation.