Different cranial nerve schwannomas pose different management challenges.

     Our purpose was to evaluate the role of Gamma Knife radiosurgery (GKS) in the treatment of trigeminal schwannomas.

     From Feb 2004 to May 2010, 41 patients with trigeminal schwannomas treated with GKS were reviewed. GKS was the primary treatment modality in 28 cases and followed microsurgery in 13 cases.

       The mean diameter of the 41 tumors was 22 mm (ranged 10-43 mm) and the tumors ranged in volume from 1 to 37 cm3 (mean 9 cm3) . The maximum dose irradiated to tumor was 20 to 38 Gy (mean 29.2 Gy) , the tumor margin dose ranged from 10 to 15 Gy (mean 12.8 Gy).

     41 patients had been followed for 12 to 73 months (mean 38 months). Mild numbness or diplopia relieved completely in 8 patients after GKS treatment. Improvement of neurological deficits was seen in 18 , unchanged dysfunction or slightly worsening of trigeminal nerve deficits in 11. Four patients had mild worsened symptoms at different time because of tumor progression. Tumor growth control : tumor disappeared after GKS treatment was observed in 7 cases from 20 to 48 months after , a marked decrease in volume was observed in 22 cases , unchange in 8 cases and increase in 3 cases. The control rate of the 35 tumors was 90.2 % (37/ 41).

     This was a retrospective study.

     Small and middle-size trigeminal schwannomas are the best candidates for GKS.

     Stereotactic radiosurgery is an effective and minimally invasive management option in patients with residual or newly diagnosed trigeminal schwannomas.