Stereotactic Gamma Knife Radiosurgery for the Treatment of Angiographically Occult Vascular Malformations(AOVMs)

Kwon, Yang; Lee, Jung Kyo; Kwun, Byung Duk; Lee, Dong Joon; Whang, Chung Jin

Abstract

In recent years, an increasing number of patient with AOVMs have been recognized using MRI. When an AOVM is located in a region associated with an unacceptable surgical risk, stereotactic radiosurgery offers an alternative treatment. We treated 21 patients with AOVM using gamma knife radiosurgery from June, 1990 to December, 1993 at Asan Medical Center. The indications for radiosurgery were as follows:1) Patients who had episodes of hemorrhage from a lesion that had the characteristic images of AOVM in MRI. 2) Patients who had seizures and the focus of these seizures corresponded to the lesions. 3) Patients were excluded if the lesions were located superficially or were accessible to microsurgery. Nine patients presented with hemorrhages and twelve with seizures. The marginal dose was ranged from 10 to 25 Gy at or above the 50% isodose line. Of eight patients followed 12 months or less after radiosurgery, two patients had improved neurologic deficits and one had decreased the seizure frequency with mediciation. Among seven patients followed 12-24 months, MRI showed a reduction of the lesion in one patient and no change in five patients. One patient had perifocal edema. In two patients with seizures, one patient was seizure free without medication and one patient was controlled with medication. In six patients between 24 and 44 months, two patients had smaller lesions and three patients had perifocal edema. Among four patients who had seizures, one patient was seizure free without medication and three had decreased the seizure frequency with medication. Postoperative complications developed two patients, but one patient showed improvement of neurologic deficits after a short period of steroid medication. Stereotactic radiosurgery offers a treatment to a selective patients with intracranial AOVMs.