Abstract
Purpose: :
By delivering a single fraction of high dose radiation, stereotactic radiosurgery (SRS) theoretically minimizes damage to surrounding structures and is increasingly used as either an adjunctive or alternative therapy for a variety of intracranial lesions. We sought to evaluate the visual findings in individuals treated by SRS for intracranial pathology.
Methods: :
Retrospective chart review with particular emphasis on ophthalmic manifestations of patients undergoing SRS who were seen in the neuro–ophthalmology clinic at one institution.
Results: :
A total of 263 patients who underwent SRS were evaluated in the neuro–ophthalmology clinic over a 20–year period. Women comprised 59.7% of patients and men 40.3% with an average age of 43.5 years (range 3–78 years). Pituitary tumors comprised the majority (60.5%) of intracranial lesions (ACTH–secreting: 21.7%, GH–secreting: 13.7%, non–secretory 18.3%, prolactinoma 6.1%, and FSH/TSH 1%) followed by meningiomas (12.9%). The remaining 25.9% of lesions included craniopharyngiomas, AVMs, seizure disorders, metastatic tumors, etc. Neuro–ophthalmic examinations were done prior to SRS in 81% of the cases analyzed. Of all patients seen prior to SRS, 16% had one or more cranial nerve palsies (CNP) and 10.4% had decreased central visual acuity (Va), while 36.3% had a visual field (VF) defect. It is important to note that 69.6% of patients had surgical or medical intervention (other than SRS) prior to their neuro–ophthalmic exam. 35% of all charts had visual examination data after SRS treatment. Information from return–patient visits ranged from 0 to 168 months (average: 13.8 months). Of the post–SRS patients, 36.0% had one or more CNP, Va was decreased in 22.0%, and VF defects existed in 46.2%.
Conclusions: :
Most candidates for SRS have intracranial lesions that are in close proximity to the afferent or efferent visual pathways. As a result, SRS may induce cranial nerve palsies or produce radionecrosis, which may affect the visual pathways by damaging the optic nerve and chiasm. Since the primary pathology or previous surgical intervention often leads to persistent neuro–ophthalmic deficits, quantitative evaluation prior to each intervention, including SRS, is essential. Until then, a conservative approach to lesions near the visual pathways is currently the best recommendation to minimize collateral damage.
Keywords: radiation therapy • clinical (human) or epidemiologic studies: outcomes/complications • visual impairment: neuro-ophthalmological disease