Abstract: Objective A retrospective analysis assessed the efficiency of gamma knife radiosurgery for nonfunctioning pituitary adenoma involving visual pathway.Methods Imaging and endocrinological evaluations following gamma knife radiosurgery were performed in 295 patients with nonfunctioning pituitary adenoma,and the patients were divided into two groups according to the tumor involving visual pathway or not,followed up from 6 to 106 months(average 35 months).The mean margin dose of 82 cases of visual pathway involved patients was 13.4 Gy and the visual pathway suffered an average radiation dose of 8.6 Gy(7 to 10 Gy).To the 213 cases of visual pathway non-involved patients,the average margin dose was 14.7 Gy and the visual pathway suffered 6.2 Gy(3 to 9 Gy).Results 47 cases(57.3%) of tumor volume decreasing,30 cases(36.6%) of remaining unchanged,and 5 cases(6.1%) of increasing were found in the group of 82 visual pathway involved patients,2 cases presenting visual impairment.149 cases(70.0%) of tumor volume decreasing,61 cases(28.6%) of remaining unchanged,and 3 cases(1.4%) were found in the group of 213 visual pathway non-involved.The overall tumor control rate was 97.3%.7 patients suffered new hormone deficits following gamma surgery.Conclusion Gamma knife radiosurgery is efficient and safe for nonfunctioning pituitary adenomas,especially for visual pathway non-involved patients with few complications.But serious consideration should be taken for patients with obvious visual pathway compression.An intensive dose plan is essential to reduce the incidence of optic neuropathy.

Key words: gamma knife radiosurgery, nonfunctioning, pituitary adenoma