Objective:

To highlight the potential delayed risk of radiation-induced optic neuropathy (RION) following photon radiotherapy of middle cranial fossa lesions and to provide a comprehensive review of its clinical presentation, diagnostic complexities, and potential early management strategies.

Background:

Middle cranial fossa lesions often present with a variety of symptoms including cranial neuropathies, headache, and visual disturbances. Radiotherapy is frequently employed as definitive or adjunctive treatment for tumors in this region but carries the risk of RION, a delayed complication marked by painless, often irreversible vision loss. The incidence of RION in patients receiving radiotherapy to the middle cranial fossa is estimated to be between 0.5-5%, depending on the dose, proximity to the optic pathways, and treatment technique. 

Design/Methods:

Case Report

Results:

A 57-year-old woman with a remote history of right cavernous sinus meningioma treated with radiation therapy and a recent admission for idiopathic left optic neuritis managed with intravenous (IV) steroids presented to the Emergency Room (ER) with acute, painless right eye vision loss. There were no motor or speech deficits noted on exam. Magnetic resonance imaging (MRI) showed enhancement of the right pre-chiasmatic optic nerve and atrophy with T2 hyperintensity of the left optic nerve. Cerebrospinal fluid (CSF) was negative for inflammatory or demyelinating markers and no other brain or spinal cord lesions were seen on imaging. Vision did not improve with IV methylprednisolone or plasma exchange (PLEX). Review of prior radiotherapy dose maps suggested findings were consistent with radiation-induced optic neuropathy (RION). The patient received IV bevacizumab without significant improvement in vision.

Conclusions:

We report a rare case of delayed bilateral RION as a result of conventional photon radiotherapy of a middle cranial-fossa lesion. Although uncommon, RION is associated with significant morbidity and presents ongoing diagnostic and therapeutic challenges due to its irreversible nature and nonspecific imaging findings.