Radiosurgical management of benign cavernous sinus tumors: Dose profiles and acute complications

OBJECTIVE: Radiosurgery has emerged as an alternative treatment modality fo r cranial base tumors in patients deemed not suited for primary surgical ex tirpation, patients with recurrent or residual tumor after open surgery, or patients who refuse surgical treatment. We review our short-term experienc e with radiosurgical management of cavernous sinus region tumors with the L eksell gamma knife. METHODS: From August 1994 to February 1999, 69 patients with cavernous sinu s lesions were treated in 72 separate treatment sessions. The tumor type di stribution was 29 pituitary adenomas, 35 meningiomas, 4 schwannomas, and 1 paraganglioma. The median follow-up was 122 weeks. Lesions were stratified according to a five-level surgical grade. The grade distribution of the tum ors was as follows: Grade I, 13; Grade II, 21; Grade III, 19; Grade IV, 12; Grade V, 4. Median tumor volume was 4.7 cm(3). The median radiation dose w as 15 Gy to the 50% isodose line. Median maximal radiation dose was 30 Gy. RESULTS: Analysis of tumor characteristics and radiation dose to optic nerv e and pontine structures revealed a significant correlation between distanc e and dose. Much lower correlation coefficients were found between tumor vo lume and dose. One lesion in this series had evidence of transient progress ion and later regression on follow-up radiographic studies. No other lesion s in this series were demonstrated to have exhibited progression. Complicat ions after radiosurgical treatment were uncommon. Two patients had cranial nerve deficits after treatment. One patient with a surgical Grade III pitui tary adenoma had VIth cranial nerve palsy 25 months after radiosurgical tre atment that spontaneously resolved 10 months later. A patient with a bilate ral pituitary adenoma experienced bilateral VIth cranial nerve palsy 3 mont hs after treatment that had not resolved at 35 months after treatment. Six patients with preoperative cranial nerve deficits experienced resolution or improvement of their deficits after treatment. One patient with a prolacti n-secreting adenoma experienced normalization of endocrine function with re turn of menses. CONCLUSION: Radiosurgical treatment represents an important advance in the management of cavernous sinus tumors, with low risk of neurological deficit in comparison with open surgical treatment, even in patients with high sur gical grades.