TREATMENT OF CRANIAL BASE MENINGIOMAS WITH LINEAR-ACCELERATOR RADIOSURGERY

OBJECTIVE: Radiosurgery is increasingly being used to treat cranial ba se tumors. Since 1989, 55 patients with cranial base meningiomas were treated at Stanford University Medical Center with linear. accelerator radiosurgery. An analysis of the clinical and radiographic results of this patient population was the focus of this study. METHODS: The mea n patient age was 55.1 years (range, 28-82 yr). The mean tumor volume was 7.33 cm(3) (range, 0.45-27.65 cm(3)). The radiation dose averaged 18.3 Cy (range, 12-25 Gy), delivered with an average of 2.2 isocenters (range, 1-5). Patients were evaluated retrospectively through clinic notes from follow-up examinations, and residual tumor volume was measu red during follow-up imaging studies, The length of follow-up averaged 48.4 months (range, 17-81 mo). RESULTS: Tumor stabilization after rad iosurgery was noted in 38 patients (69%), shrinkage in 16 patients (29 %), and enlargement in only 1 patient (2%). The results of follow-up m agnetic resonance imaging demonstrated decreased central contrast upta ke in 11 meningiomas (20%), possibly indicating evidence of central tu mor necrosis or tumor vessel obliteration. Neurological status was imp roved in 15 patients in the series (27%) and unchanged in 34 patients (62%). Three patients (5%) died during the follow-up period, all as a result of causes other than tumor progression. Three patients (5%) dev eloped new permanent symptoms (one patient with seizures, one patient with mild right hemiparesis, and one patient with both vagal and hypog lossal nerve palsy). Ail other complications were transient, including partial trigeminal nerve palsy in seven patients and diplopia in thre e patients. The 2-year actuarial tumor control rate was 98%. CONCLUSIO N: Although our follow-up period is short, this experience corroborate s previous reports that radiosurgery can be used to ablate selected sm all cranial base meningiomas, with good clinical results and modest mo rbidity.