Noncoplanar volumetric modulated arc therapy for patient with optic nerve sheath meningioma: a case report and literature review

A 74-year-old female presented with progressive oculus dexter (OD) visual deterioration caused by optic nerve sheath meningioma (ONSM). The Farnsworth D-15 Dichotomous Color Blindness Test progressed from 3/15 to 1/15 in OD. The visual acuity with correction (VACC) changed from 0.4 to 0.3 in OD after 1 month of medication therapy. A total dose of 54 Gy in 30 fractions was delivered to the ONSM with the noncoplanar volumetric modulated arc therapy (VMAT) technique (Versa HD, Elekta, Crawley, West Sussex, UK). Color discrimination was improved from 1/15 to 13/15 after the patient received 27 Gy in 15 fractions. The VACC of the right eye treated with 54 Gy was improved from 0.3 to 0.6 at 9 months and to 1.0 at 15 months after radiotherapy (RT). There was no neuropathy, visual impairment, cognitive problem or retinopathy upon ophthalmologic examination during or after RT. The size of the tumor was stable, which was confirmed by radiographic studies. The fractionated noncoplanar VMAT technique provides delicate balance between dose coverage and normal tissues protection with well tumor control and improvement in visual function without treatment-induced morbidity.