Abstract
Abstract: :
Purpose: To describe multifocal Visual Evoked Potential (mfVEP) findings in patients presenting with atypical optic neuritis (ON). Methods: Between Oct. 1998 and Nov. 2003, 46 patients with optic neuritis underwent mfVEP testing. Of these, 12 were classified as atypical optic neuritis. In 5 cases age was the primary criterion, with 3 being young (under 15 years) and 2 being old (72 and 78 years) for typical ON. In 4 cases, the clinical presentation suggested another etiology (ischemic optic neuropathy (ION), perineuritis, intracranial lesion, retinal origin). One patient had bilateral, simultaneous ON, one had neuroretinitis, one had chronic demyelinating optic neuropathy, and one patient reported loss of vision only upon exercising/hot showers (Uhthoff’s phenomenon). Monocular mfVEPs were obtained from each eye using VERIS (EDI). Four active electrode placements and 3 channels of recording were employed as previously described [1–3]. Latencies were measured via a computer program and checked by hand. All patients also were tested with static automated perimetry (24–2 program, Humphrey, Zeiss). Results: Eleven patients showed local delays in the mfVEP. Only the patient with Uhthoff’s had normal latencies in both eyes. Interestingly, the patient with bilateral simultaneous optic neuritis had delays in only one eye; the eye with the better visual field during the acute phase. The patient with neuroretinitis demonstrated substantial delay. The patient with chronic demyelinating neuropathy showed progressively diminished amplitudes and prolonged delays in the absence of any acute episode. The patient diagnosed with optic perineuritis showed large delays on mfVEP, and a subsequent MRI demonstrating multiple demyelinating plaques confirmed ON. The patient initially diagnosed with ION showed delays and subsequent recovery of the visual field. The patient with a junctional defect of Traquair demonstrated delays on mfVEP, which combined with MRI, confirmed inflammation of the junction of the optic nerve and the adjacent optic chiasm. Conclusion: All but one of the patients with atypical ON showed clearly delayed mfVEP responses, and these delays often aided the diagnosis of ON. In many cases these delays were very local and may not have appeared on a conventional VEP. 1. Hood & Zhang (2000); 2. Hood et al (2002) AO. 3. Hood & Greenstein (2003), Prog Ret Eye Res
Keywords: electrophysiology: clinical • neuro–ophthalmology: diagnosis • neuro–ophthalmology: optic nerve