Stereotactic radiosurgery for brainstem arteriovenous malformations: factors affecting outcome

Area of Science:

• Neurosurgery
• Radiation Oncology
• Vascular Neurology

Background:

• Management of brainstem arteriovenous malformations (AVMs) presents unique challenges due to limited therapeutic options.
• Long-term outcomes of stereotactic radiosurgery (SRS) for brainstem AVMs require further elucidation.

Purpose of the Study:

• To evaluate the long-term neurological and radiological outcomes of SRS for brainstem AVMs.
• To identify factors influencing treatment success and complication rates.

Main Methods:

• A retrospective review of 50 patients with brainstem AVMs treated with gamma knife surgery between 1987 and 2002.
• Analysis of treatment parameters, including radiation dose, isocenters, and dose planning techniques (pre- and post-1993).
• Assessment of angiographic obliteration rates and neurological complications during a mean follow-up of 72 months.

Main Results:

• An actuarial obliteration rate of 66% was achieved at final follow-up, with a low annual hemorrhage rate (1.7% in the first 3 years, 0% thereafter).
• Treatment with two or fewer isocenters and a spherical nidus shape correlated with higher obliteration rates (80% vs. 44%).
• Neurological complication rates decreased from 20% before 1993 to 7% after implementing MRI-based dose planning, with older age, tectal location, and higher radiosurgery scores associated with increased complications.

Conclusions:

• Stereotactic radiosurgery offers a viable treatment option for brainstem AVMs, achieving complete obliteration in approximately two-thirds of cases.
• Advancements in 3D imaging and conformal dose planning have significantly reduced the risk of adverse radiation effects.
• Optimal outcomes are observed in younger patients with spherical AVMs not involving the tectal plate.