gms | German Medical Science

Objective: Large arteriovenous malformations (AVM) of the brain pose a challenge for all treatment options - microsurgical resection, embolization and radiosurgery. Some may be treated using multimodal management. Radiosurgical volume staging and hypofractionated radiotherapy options are further published treatment modalities. The purpose of this work was to evaluate the efficacy of radiosurgery (RS) and hypofractionated stereotactic radiotherapy (hfSRT) in the treatment of large AVMs.

Methods: 20 patients (pts) with large brain AVMs (volume > 10 cm³⁾, treated from 2001 to 2012 with RS (n=13) or hfSRT (n=7), were retrospectively evaluated. 9 pts were male, and 11 were female. Patient age ranged from 14 to 65 years (mean, 39 years). 6 pts (30%) were initially symptomatic with an AVM bleeding, 5 pts (25%) with seizures, 7 pts with headaches or a mild focal neurological deficit (35%), only in 2 pts (10%) the AVM was an accidental diagnosis. 11 pts (55 %) had previously undergone partial embolization and 2 pts (10%) prior microsurgery. Clinical outcome was measured using the modified Rankin Scale (mRS). Adverse events were evaluated with the Common Terminology Criteria (CTC) scale 3.0.

Results: One patient was lost for follow-up (FU). The mean FU was 47 months (range, 5–108 months). The nidus volume (= target volume = TV) ranged from 10 to 26 cm³ (median, 15.4 cm³). The mean radiosurgical dose was 18.75 Gy (range, 16-20 Gy) at the isocenter of the TV encompassing the 80% isodose. For hfSRT, the median total dose was 35 Gy (range, 35-55 Gy) at the isocenter of the TV encompassing the 90-95% isodose. In 10 (50%) of these pts there was complete AVM obliteration proven by magnetic resonance angiography (MRA), in 6 cases additionally confirmed by conventional angiography. In the other 9 pts so far a reduced flow could be demonstrated by MRI/MRA. Only one patient experienced a worsening of the mRS (0 > 2), 4 pts were improved at FU (mRS 2 > 0, mRS 2 > 1, 2 x mRS 1 > 0). The rare complications included one temporary radionecrosis with transient visual field disorder after hfSRT and one deteriorated hemiparesis after RS. There was no AVM bleeding in the study period.

Conclusion: RS and hfSRT alone or combined with embolization or surgery provide a good treatment option with an acceptable rate of obliteration and side effects in those otherwise difficult to treat large brain AVMs. In some cases, hfSRT opens up the possibility of a definitive re-treatment with radiosurgery.