Optimal management in optic nerve sheath meningioma – A multicentre study and pooled data analysis

The treatment efficacy of radiotherapy for optic nerve sheath meningioma

OBJECTIVES

Optic nerve sheath meningioma (ONSM) is a rare benign tumour that accounts for approximately 2% of all orbital tumours. Radiotherapy has gradually become an important treatment for ONSM because of its good effect in preserving or improving vision. We aimed to explore the effect of radiotherapy on tumour control and vision preservation/improvement in patients with ONSM.

METHODS

Forty-three patients with primary ONSM treated in our institution from 2015 to 2021 were enrolled. The irradiation dose was from 50.4 to 54 Gy with 28-30 fractions. We evaluated the tumour volume on MRI or CT, and visual acuity before and after the radiotherapy.

RESULTS

Thirty-four patients (79%) experienced a vision decrease at diagnosis. The mean duration of follow-up was 54.1 months (ranges: 18-93, median: 56). Among 25 patients who had tumour evaluation using MRI, 16 patients (37.2%) showed stable tumours, 7 patients (16.3%) had tumour shrinkage, but 2 patients (4.7%) experienced tumour progression. Among the 39 patients performing vision acuity evaluation, 16 patients (37.2%) had vision improvement or recovery. 16 of the 23 patients without vision improvement demonstrated severe visual loss at diagnosis. Two patients had evidence of tumour progression during the follow-up. Additionally, 4 (10.2%) patients had dry eyes, 7 (17.9%) patients experienced watery eyes, and 3 (7.7%) patients had eye swelling. Patients with vision loss for more than 12 months had a lower possibility of vision recovery than those with vision loss for less than 12 months.

CONCLUSIONS

Radiotherapy such as IMRT, VMAT, and 3D-CRT plays an important role in the treatment of ONSM. The probability of vision recovery is lower in patients with severe vision loss at diagnosis or the duration of vision loss is more than 12 months.

Radiotherapy and Radiosurgery in the Management of Optic Nerve Sheath Meningiomas: An International Systematic Review and Meta-Analysis of Twenty Studies

BACKGROUND

Optic nerve sheath meningiomas (ONMs) are often managed with radiotherapy (RT) with the goal of achieving radiographic local control (LC) and preventing deterioration of visual acuity (VA). We aimed to perform a systematic review and meta-analysis of outcomes for patients with ONM treated with RT.

METHODS

The PICOS/PRISMA/MOOSE selection criteria were used to identify studies. Primary outcomes were stable or improved VA and radiographic LC at last follow-up. The secondary outcomes were incidences of radiation-induced retinopathy and xerophthalmia and stable or improved visual fields (VFs). Weighted random-effects meta-analyses using the DerSimonian and Laird methods were conducted to characterize effect sizes. Mixed-effects regression models were used to examine potential correlations between gross tumor volume (GTV) and outcomes.

RESULTS

In total, 444 patients with ONM across 20 published studies were included. The estimated LC rate was 99.8% (95% confidence interval [CI], 98.3%-100%), and the estimated proportion of patients with stable or improved VA or VF was 89.7% (95% CI, 86.2%-92.4%) and 93.3% (95% CI, 89.5%-95.8%), respectively. Estimated incidences of radiation-induced retinopathy and xerophthalmia were 7.2% and 10.1%, respectively. GTV was significantly associated with VA (P = 0.014) with estimated VA rates of 96.4%, 91.4%, and 80.5% for GTVs of 2.0, 3.0, and 4.0 cm³, respectively.

CONCLUSIONS

RT was well tolerated, with excellent LC achieved. Nearly 90% of patients noted either stability or improvement in VA and VF. Larger ONMs were associated with poorer VA.

Salvage Radiosurgery for Optic Nerve Sheath Meningioma

Optic nerve sheath meningiomas (ONSMs) are rare and benign tumors that affect the optic nerve. Although surgical decompression may be used for large tumors that cause mass effect on the surrounding structures, the mainstay of treatment is radiotherapy. We report the case of a 54-year-old female patient who presented with progressive vision loss due to a recurrent right ONSM despite fractionated radiotherapy eight years prior and the subsequent interval regression of the tumor. The optical coherence tomography at the time of recurrence revealed thinning of the right retinal nerve fiber layer. She underwent salvage stereotactic radiosurgery using a marginal dose of 15 Gy. At six months post-radiosurgery, the patient had a dramatic improvement in visual acuity and visual fields despite persistent thinning of the retinal nerve fiber layer. This case illustrates how salvage radiosurgery can be a useful treatment modality in these challenging situations. This tumor’s exophytic growth and the steep dose fall-off of Gamma Knife radiosurgery might favorably affect visual recovery. However, the outcomes of single-session radiosurgery for ONSMs should be further evaluated.

Approach to patient with unilateral optic disc edema and normal visual function

In patients with swollen optic nerve head and normal visual function, optic disc drusen (ODD) is the most common diagnosis. The best tests for detecting ODD are funds autofluorescence and enhanced-depth imaging ocular coherence tomography (EDIOCT). After ODD has been ruled out, asymmetric papilledema should be assumed to be the cause and MRI of the brain and orbits with contrast and venography should be performed in all patients. It allows one to look for indirect signs of increased inctracranial pressure (ICP), optic perineuritis, and other inflammatory or compressive processes affecting optic nerve or its sheath such as optic nerve sheath meningioma. If imaging signs of raised ICP are present, lumbar puncture should be performed with measurement of opening pressure and analysis of cerebrospinal fluid (CSF) contents in all patients with fever, meningismus or neurologic deficits as well as patients who are not in the typical demographic group for idiopathic intracranial hypertension (IIH). Optic nerve sheath enhancement on MRI should prompt work-up for causes of optic perineuritis. When the appropriate neuroimaging is normal, the differential diagnosis is limited and ophthalmological consultation is necessary to determine whether other subtle ocular abnormalities are present on biomicroscopic and dilated fundus examination.