Stereotactic Radiation Therapy for Optic Nerve Sheath Meningioma; An Experience at Ramathibodi Hospital
Chomporn Sitathanee MD*, Mantana Dhanachai MD*, Anuchit Poonyathalang MD***, Lojana Tuntiyatorn MD**, Veerasak Theerapancharoen MD****
Affiliation : * Division of Radiation Oncology, Faculty of Medicine Ramathibodi Hospital, Mahidol University ** Division of Diagnostic Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University *** Department of Ophthalmology, Faculty of Medicine Ramathibodi Hospital, Mahidol University **** Division of Neurosurgery, Faculty of Medicine Ramathibodi Hospital, Mahidol University
Objective : To evaluate results of stereotactic radiotherapy for the treatment of optic nerve sheath meningioma
(OM) at Ramathibodi Hospital.
Materials and Methods : Twelve patients with primary OM were treated with stereotactic radiation between
1998 and 2005. Five patients underwent surgery and had no light perception before radiation. All patients
except one were treated with fractionated stereotactic radiotherapy (FSRT). Mean average dose of FSRT was
55.7 Gy; 180 cGy/fraction. One patient was treated with 15-Gy stereotactic radiosurgery.
Results : With a median follow-up of 34 months, there was no visual improvement in the five patients who were
completely blind before radiation. Visual acuity improved in four patients and remained stable in two patients.
Four of six patients had improved visual field, and five of six decreased in proptosis. Follow-up images were
available in six patients, showing minimal tumor regression in five and stable in one. No serious acute side
effect was observed. Vision became worse in one patient, who developed vitreous hemorrhage two years after
FSRT.
Conclusion : Stereotactic radiotherapy is an effective treatment for primary OM. It provides tumor control and
visual preservation with low risk of complications. However, more patients and further follow-up are needed
for long-term outcomes.
Keywords : Stereotactic radiotherapy, Optic nerve, Optic nerve sheath, Meningioma
