Multisession Gamma Knife Radiosurgery For Benign Perioptic Lesions: Outcome In 39 Patients

Keywords: meningioma, optic chiasm, vision, gamma knife, fractionated stereotactic radiotherapy

Interactive Manuscript

Ask Questions of this Manuscript:



     Radiosurgery is a well established treatment for variety of intracranial pathology. However, it may not be safe for the lesions adjacent to the optic pathway.
     The purpose of this study is to evaluate efficacy and safety of multisession Gamma knife radiosurgery (GKS) for benign perioptic lesions in which single session GKS is not feasible due to the substantial risk of visual complication.
     Thirty nine patients (18 male and 21 female, mean age 45 years old ranged from 26 to 77) were treated with multisession GKS from May 2004 to December 2008.
     Inclusion criteria were benign pathology, small to moderate size adequate for single session GKS, and close contact of the lesion with optic apparatus (< 2 mm) which prohibit optimal dose delivery in single session GKS. Twenty four patients among them underwent microsurgery before multisession GKS. Pathological diagnoses were meningioma (22), pituitary adenoma (6), craniopharyngioma(6), orbital cavernous hemangioma (3) and schwannoma(2). GKS was performed in the same method as in single session GKS except irradiation was done in 4 fractions with 12 hrs of interfractional interval. Stereotactic frame fixation was maintained during the treatment course. Mean tumor volume was 3.98 cc (0.3-16.8 cc) and median cumulated marginal dose was 20 Gy (i.e. 5 Gy / fraction). Pre- and post-GKS follow up included MRI scan with volumetry and examination of visual acuity / field.
     Mean follow up period was 35 months (9 - 64 months). Follow up MRI was available in 37 patients and tumor growth control was confirmed in 35patients (94.6%). One patient with craniopharyngioma revealed tumor progression with deterioration of vision and underwent subsequent microsurgery. The other patient with meningioma underwent additional fractionated radiotherapy. Preservation of visual function was possible in 36 patients (92%; improved in 18%, unchanged in 74%). Two patients complained subjective worsening of vision and one patient revealed progressive deterioration related to tumor progression.
     This is a retrospective study.
     Multisession GKS is a tolerable procedure without serious complication.
     It is effective and safe for the benign perioptic lesions which is not adequate candidate for single session GKS. It may be more preferable choice than radiotherapy with conventional fractionation.


Project Roles: