Neuro-ophthalmologic outcomes of standard versus hypo-fractionated stereotactic radiotherapy of AVPM

Role of hypofractionated stereotactic radiotherapy for primary optic nerve sheath meningioma

Background

Optic nerve sheath meningiomas (ONSM) are rare tumors potentially causing visual deficits. This study aims to report the anatomic and visual outcomes of patients with primary ONSM treated with hypofractionated stereotactic radiotherapy (HF-SRT).

Methods

Data of 36 patients treated with HF-SRT between 2008 and 2019 were retrospectively collected. The clinical target volume (CTV) was equal to the gross tumor volume and a 2 mm was added for the planning target volume. All responses other than progression were accepted as local control (LC). The VA grading was performed under 3 groups to provide an even distribution; 20/400 or worse, 20/40-20/400, and 20/40 or better.

Results

Median HF-SRT dose was 25 Gy and the median CTV was 1.94 cc. After a median of 106 months of follow-up, the tumor regressed in 23 (64%), was stable in 9 (25%), and progressed in 4 (11%) eyes. The overall rate of LC was 89% with 2-, 5-, 10-, and 15-year rate of 100%, 94%, 84%, and 84%, respectively. Treatment-related late toxicity rate was 11%. The VA was stable in 27 (75%) eyes, improved in 5 (14%) eyes, and worsened in 4 (11%) eyes, respectively, after HF-SRT. Female gender was the only independent predictor of an improved VA.

Conclusions

Hypofractionated stereotactic radiotherapy is a safe and satisfactory treatment option for primary ONSM without severe toxicity. It may be advisable to commence treatment before an established visual deficit of 20/400 or worse occurs, to make the most of the functional benefit.

Stereotactic radiotherapy of radiation-induced meningioma previously irradiated retrobulbar for Graves' ophthalmopathy: A case report

A 69-year-old woman was diagnosed with an asymptomatic intracranial tumor nine years ago and has been followed with annual MR imaging studies. Two years ago, the tumor had grown in size, requiring treatment. She experienced ophthalmopathy due to hyperthyroidism 27 years ago and was treated with 20 Gy in 10 fractions using parallel opposed beams to her bilateral posterior eyeballs, supplemented with steroid pulse therapy. The tumor originated in the medial aspect of the right sphenoid border and compressed the temporal lobe, while bone infiltration was observed, partially extending to the soft tissue outside the maxillary sinus. The tumor was removed by craniotomy. The pathological diagnosis was atypical meningioma (WHO grade II). Four months postsurgery, the resection cavity's tumor exhibited growth inclination, necessitating Gamma Knife radiosurgery. Radiation planning was executed at a marginal tumor dose of 30 Gy in 5 fractions. Since the optic nerve had been previously exposed to radiation, a plan was devised to minimize radiation exposure. The dose on the optic nerve was limited to 6.9 Gy in 5 fractions. She did not experience any visual or visual field disruptions postradiation. This is a case of radiation-induced meningioma resulting from radiation therapy for Graves' ophthalmopathy and is the first reported case of a grade II meningioma. The patient's condition calls for adjuvant radiation therapy following surgical removal. Accordingly, a radiation treatment plan that safeguards the optic nerve, which was previously exposed to radiation, was deemed indispensable.