Optic nerve sheath meningiomas: The role of stereotactic radiotherapy

Purpose: Primary orbital meningiomas are rare, the usual site of origin being the optic nerve sheath. These represent 1-2% of all meningiomas. This is a review of a single centre's experience. Materials and Methods: Between 1990 and February 2004 26 patients were referred and 16 patients were treated by radiotherapy (mean age 51 years). This retrospective study evaluated 16 patients - 18 tumours (I patient with NF2 had bilateral optic nerve tumours and I optic nerve was treated twice). Nine patients were treated with newly diagnosed lesions, and 7 recurrent after prior treatment including radiotherapy for I patient. The median duration of symptoms to onset was 2 months. Treatment consisted of stereotactic radiosurgery (median dose 20Gy) where vision was not a consideration, and fractionated SRT (median dose 5,040 Gy in 28 fx) for vision preservation. Results: Median follow up is 46.8 months. Recurrence after SRT occurred in I patient (a geographical miss) leading to progressive disease and blindness, this new lesion was treated with stereotactic radiosurgery, the tumour controlled with subsequently some vision improvement. Only one other patient had progressive disease, thus for an ultimate local of 94%. For fractionated patients only the above patient had worse vision after treatment. Conclusion: Radiotherapy provides high local control, utilising fractionated treatment provided it covers the full length of the nerve, is necessary to have the option of preserving vision. Copyright (c) 2006 S. Karger AG, Basel.