Visual function assessed by visually evoked potentials in adults with orbital and other primary intracranial tumors

Purpose: The purpose of this study was to assess visual function by visually evoked potentials in adults with orbital and other primary brain tumors affecting the optic pathway.Methods: In this retrospective case–control series, patients with orbital (intraconal and extraconal) or midline/chiasmatic tumors were included. Visually evoked potentials using pattern-reversal visually evoked potential and flash visually evoked potential stimuli were performed according to the international standards. Outcome measures were visually evoked potential parameters of amplitude (µV) and peak times (ms) measured both for the P100 component (pattern-reversal visually evoked potentials) and the N2P2 complex (flash visually evoked potential). Individual results were also compared with gender-based normative values.Results: A group of 21 adult patients (17 females) and age- and sex-matched controls were evaluated. Tumor location was intraconal (6 meningiomas, 3 hemangiomas, 1 glioma), extraconal (6 meningiomas), and midline (3 pituitary adenomas, 2 hypothalamic/chiasmatic low-grade gliomas). Abnormal fundus (76%), abnormal pupillary reflexes (71%), reduced visual acuity (62%), strabismus (48%), and proptosis (38%) were present. Visually evoked potential abnormalities were found in at least one eye of all cases. Affected eyes had significantly reduced amplitudes and prolonged peak times for pattern-reversal visually evoked potentials (p< .001) and significantly reduced amplitudes for flash visually evoked potential (p< .001). In unilateral orbital tumors, abnormally prolonged pattern-reversal visually evoked potential peak times were also detected in some contralateral eyes (n= 6/16).Conclusion: Visually evoked potential abnormalities were found in all adult patients with orbital and other intracranial primary tumors, even in eyes with normal exam and good visual acuity. Visually evoked potential can be used as a non-invasive ancillary test to characterize and monitor visual function in subjects with these neoplastic lesions.