Gamma knife surgery shows promise for orbital apex cavernous malformations

This paper describes the use of multisession gamma knife radiosurgery to treat orbital apex cavernous malformations with optic neuropathy.

Study design

The authors performed a retrospective, interventional, noncomparative study of 12 patients with optic neuropathy stemming from presumed orbital apex cavernous malformations.  All patients underwent multi-fractionated gamma knife radiosurgery (GKRS) with 4 fractions and 12-hour intervals.

Outcomes

The average age was 40.2 years and 66.7% of patients were male. The median marginal dose delivered in a session was 5 Gy with a median cumulative dose of 20 Gy. Patients were followed for an average of 28.5 months.

Ten patients showed improvement in BCVA, and 6 of 10 patients with a preexisting relative afferent pupillary defect (RAPD) show resolution of the condition. All 12 patients had a preexisting visual field defects; of these, 7 had complete resolution, 3 had partial resolution and 2 remained unchanged. Tumor shrinkage was observed in all patients.

Limitations

This a retrospective study with a large variation in follow-up. Diagnosis of cavernous malformation was made clinically and radiologically. It is possible that some lesions were other masses (e.g., meningioma or schwannoma). This would only be able to be confirmed with biopsy.

Clinical significance

This is a valuable study demonstrating the nonsurgical treatment of orbital apex cavernous malformations. Surgical resection of these lesions can be challenging and carries significant risk. The use of gamma knife surgery in the treatment of these lesions appears to be promising.