Abstract
Abstract: :
Purpose: To assess whether latencies of the multifocal visual evoked potential (mfVEP) change over time in patients with recovered optic neuritis (ON)/multiple sclerosis (MS). Methods: The 12 patients in this study all had ON/MS in at least one eye as confirmed on standard clinical and radiological criteria and had a mfVEP test following recovery. At least 6 months after this initial test, repeat monocular mfVEPs (VERIS, EDI) and static automated perimetry (24–2 program, Humphrey, Zeiss) were obtained from each eye. For the mfVEP, a dartboard display of 60 sectors (VERIS software) and three channels of recording were used. Recordings were analyzed using Matlab software previously described [1]. Monocular and interocular latencies were obtained and expressed relative to a normative group of 100 individuals [2]. The repeat mfVEP data for the patients were compared to those of 50 normal subjects, who were tested approximately one year apart [3]. The median latency for a given eye was considered delayed when the repeat latency difference (day 2–day 1) exceeded that of the 95% confidence interval for the 50 normals. Results: The initial mfVEP tests were performed 3 weeks to 32 months (median = 2 mo.) after the acute ON episode. Repeat tests were done 6 to 56 months (median = 14.8 mo.) after the initial mfVEP tests. Fourteen of the 24 eyes were classified as affected by optic neuritis. Of the 14 affected eyes, the latency of 3 remained unchanged (median delays of –2.5, 0.8, 2.1 ms), 3 increased (2.5, 1.7, 11.7 ms) and 8 decreased (–2.5 to –12.5 ms). Of the 10 eyes originally unaffected, 7 eyes remained unchanged (–1.7 to 1.7 ms) and normal, while 3 developed prolonged latencies (3.3, 10.0, 19.2 ms). Conclusions: Consistent with earlier studies, 3 of the originally unaffected eyes developed prolonged latencies, suggestive of subclinical optic neuritis episodes. Interestingly, 8 of the 14 eyes known to be affected by ON showed decreased latencies and, thus, evidence of optic nerve recovery. 1. Hood & Greenstein (2003) PRER. 2. Hood et al. in press. DOOP. 3. Fortune et al. in press DOOP.
Keywords: electrophysiology: clinical • neuro-ophthalmology: optic nerve