Name

Œdème papillaire et radiothérapie pour méningiome de la gaine du nerf optique

We report the cases of 4 female patients who developed, or worsened, optic disc swelling after undergoing radiation therapy for the management of sight-threatening optic nerve sheath meningioma (ONSM).

All 4 patients presented with optic disc swelling related to anterior ONSM. Three patients were treated with proton beam therapy (PrT, total dose 51 CGE) and 1 patient with fractionated intensity modulated photon radiation therapy (PhT, total dose 50.6 CGE). Two of them (1 treated with PrT and 1 treated with PhT) experienced worsening of optic disc swelling immediately after treatment. The other 2 patients, treated with PrT, had initial resolution of optic disc swelling at 1 and 3 months after treatment, before it recurred at 3 months and 9 months, respectively. In all cases, clinical examination showed decreased visual acuity and visual field at the time of worsening of optic disc swelling. Magnetic resonance imaging (MRI) revealed optic nerve enhancement indicative of radiation optic neuropathy in only one patient treated with PrT. Said patient had the worse visual function, and no improvement was observed after treatment. In all cases, optic disc margins were elevated and there was hyperemia related to capillary dilation. However, no hemorrages or cotton wool spots were observed. 

Oral corticosteroids alone allowed recovery for 1 PhT patient. The other three patients treated with PrT required 1 sub-tenon injection of Kenacort, which was enough to allow resolution of the optic disc swelling only in 1 patient. The other 2 PrT patients had 3 intravitreous injections of anti-VEGF, which was efficient in one patient. Finally, the last PrT patient had to undergo 2 additional injections of intravitreal implant of dexamethasone to obtain sustained resolution of the optic disc swelling until her last followup, 6 months after the second injection.

Optic disc swelling in the setting of ONSM and radiotherapy is a poorly understood sight-threatening disease. It is possible that radiation therapy triggers an inflammatory response that maintains and worsens an already existing optic disc swelling. Whether this should be considered radiation optic neuropathy is unclear, since the MRIs did not show the specific optic nerve hypersignal seen in this condition. Because of its rarity, there is no consensus on how to treat patients. In our 4 cases, we chose an escalation therapy approach, which was successful at resolving optic disc edema, but did not allow conservation of visual acuity in one PrT patient, who might have benefited from ealier intravitreal steroids injections. 

Secondary optic disc swelling causing visual decline is a poorly documented adverse event of PhT and PrT for ONSM. Patients with optic disc edema should be advised regarding this complication. Radiation therapy should be used in these cases only if there is a risk of permanent vision loss. Patients should be closely followed up for at least 3 to 6 months after radiation therapy to screen for worsening or recurrence of optic disc swelling. Preventive anti-inflammatory treatment, such as oral steroids, might also be considered.