Equiluminant red-green and blue-yellow VEPs in multiple sclerosis.

Objective: To examine the association of visual evoked potential (VEP) latency and high-contrast visual acuity (VA) with cognitive function in MS patients using a standardized computerized battery. Background Cognition and vision are now recognized as important domains for clinical trials assessment in MS. The correlation of VEP conduction delay and VA with cognitive impairment has not been described. Design/Methods: Participants received a VEP evaluation as well as a Snellen vision test and completed a standardized, validated MindStreams battery designed to detect mild impairment (NeuroTrax Corp., NY) in their primary language. VEP latency categories were: normal =113 and =130 and =150 and 170 msec. Results: Among MS patients (n=435, 870 eyes), Accounting for age, disease duration, and within-patient, inter-eye correlations, abnormal VEP latency was associated with poorer overall battery performance (Global Cognitive Score, p Conclusions: Abnormal VEP latency and high-contrast VA in patients with MS may be associated with reduced cognitive function, particularly in domains related to executive function. Longer VEP latency may be particularly related to poorer visual spatial processing. Further studies will examine the role of afferent visual dysfunction and retinal axonal and neuronal loss in the relation of VEP latency to cognitive impairment and work disability in MS cohorts. Disclosure: Dr. Chahin has nothing to disclose. Dr. Balcer has received personal compensation for activities with Biogen Idec, Vaccinex and Bayer as a consultant and has received honoraria from Biogen Idec and Novartis. Dr. Zarif has received personal compensation for activities with Biogen Idec as a consultant. Ms. Bumstead has received personal compenstion for activities with Biogen Idec and Teva Neuroscience as a consultant. Dr. Fafard has nothing to disclose. Dr. Mebrahtu has nothing to disclose. Dr. Galetta has received personal compensation for activities with Biogen Idec Teva, and Novartis as a speaker.Dr. Galetta has received research support from Biogen Idec. Dr. Doniger has received personal compensation for activities with NeuroTrax Corporation as an employee. Dr. Gudesblatt has received personal compensation for activities with Biogen Idec, Teva Neuroscience, Lundbeck Research USA, Inc. and Medtronic as a consultant.

Prior studies have reported an association between visual evoked potentials (VEPs) and cognitive performance in people with multiple sclerosis (PwMS), but the specific mechanisms that account for this relationship remain unclear. We examined the relationship between VEP latency and cognitive performance in a large sample of PwMS, hypothesizing that VEP latency indexes not only visual system functioning but also general neural efficiency. Standardized performance index scores were obtained for the domains of memory, executive function, visual-spatial processing, verbal function, attention, information processing speed, and motor skills, as well as global cognitive performance (NeuroTrax battery). VEP P100 component latency was obtained using a standard checkerboard pattern-reversal paradigm. Prolonged VEP latency was significantly associated with poorer performance in multiple cognitive domains, and with the number of cognitive domains in which performance was ≥ 1 SD below the normative mean. Relationships between VEP latency and cognitive performance were significant for information processing speed, executive function, attention, motor skills, and global cognitive performance after controlling for disease duration, visual acuity, and inter-ocular latency differences. This study provides evidence that VEP latency delays index general neural inefficiency that is associated with cognitive disturbances in PwMS.

Optic neuritis (ON) is linked to multiple sclerosis (MS). The presence of white matter lesions on cerebral magnetic resonance imaging (MRI) predicts the risk of MS after ON with considerable accuracy. Oligoclonal bands (OCB) are present in 95 % of MS patients, and a lumbar puncture can also be valuable in the evaluation of patients with ON. We analyzed CSF findings in patients referred with ON in the context of MRI and visual evoked potential (VEP) pathology. We assessed the possible contributory role of a lumbar puncture and weigh this against disadvantages of the procedure. Between February 2003 and November 2011, 505 patients were referred by ophthalmologists to the Clinic of Optic Neuritis, Glostrup Hospital, University of Copenhagen. None had MS prior to referral. A total of 437 were included in the study, and all underwent MRI, a lumbar puncture and VEP. Patients with other organic causes of their symptoms and patients with >3 months between onset and tests were excluded. All files were reviewed retrospectively. CSF leukocytes and the IgG index were elevated in 33 and 41 %, respectively, and OCBs were detected in 61 % of patients. CSF abnormalities correlated strongly with VEP and MRI (p < 0.0001). Patients with normal VEP and MRI had a 96 % probability of a normal lumbar puncture. The contributory role of a lumbar puncture in the evaluation of ON seems negligible when patients have a normal VEP and MRI. We suggest that all patients should be evaluated with VEP and MRI before deciding on a lumbar puncture.

Background:Multiple sclerosis (MS) is a demyelinating disease of the central nervous system which has no any known definitive treatment. Studies have shown that thyroid hormones (THs) in addition to their roles in the development of the nervous system and the production of myelin have important roles in the adult's brain function. Since the only way to treat MS is the restoration of myelin, the aim of this study was to evaluate the effects of levothyroxine on visual evoked potential (VEP) impairment following local injections of lysolecithin into the rat optic chiasm.Methods:To induce demyelination, lysolecithin was injected into the optic chiasm of male Wistar rats. VEP recording was used to evaluate demyelination and remyelination before and 10, 17, and 24 days after the lysolecithin injection. The rats received an intraperitoneal injection of levothyroxine with doses 20, 50, and 100 μg/kg in different experimental groups.Results:VEP latency and amplitude showed demyelination at 10 and 17 days after an induced lesion in MS group which was reversed at day 24. Levothyroxine prevented these impairments, especially in high doses.Conclusions:According to the results, lysolecithin-induced demyelination at optic chiasm and VEP impairments can be restored by administration of levothyroxine. Therefore, THs probably have positive effects in demyelinating diseases.

Visual evoked potential — a tool in the diagnosis of hepatic encephalopathy?

Influence of Cataract Surgery on Optical Coherence Tomography and Neurophysiology Measurements in Patients With Retinitis Pigmentosa

The diagnostic application of averaged visual evoked potentials (VEPs) is illustrated in the investigation of hysterical amblyopia and multiple sclerosis. Averaged VEPs elicited either by a flash of light or a presentation of a grating lasting 100 ms were recorded from the occiput of patients. All the VEPs in hysterical amblyopia were normal. In multiple sclerosis the flash VEPs looked normal for both eyes, whereas the VEPs elicited by grating (2 and 5 c/deg) showed an increase in the latency of the first positive wave, again for both eyes. After physical exercise the VEPs from the right eye were dramatically reduced in amplitude (Uhthoff's sign).

Background: The aim was to compare the retinal nerve fibre layer (RNFL) thickness and visual evoked potentials (VEP) among eyes with multiple sclerosis (MS)‐associated optic neuritis, unaffected eyes of the same patients and eyes of disease‐free controls. Changes in RNFL thickness, visual acuity (VA) and VEP over time are evaluated in MS‐associated optic neuritis.Methods: Forty‐six eyes of 23 patients (six male and 17 female), who suffer from MS and were diagnosed with unilateral or bilateral optic neuritis, participated in the study. Forty eyes of 20 age‐ and gender‐matched controls were tested. VA measurement, optical coherence tomography and VEP were performed in all patients at presentation and at one, three and six months thereafter.Results: There was a statistically significant difference in VA between MS eyes with optic neuritis and controls (p < 0.0001), as well as between MS eyes with and without optic neuritis (p < 0.005). VA improved over time. Average RNFL thickness was reduced in MS eyes with or without optic neuritis in comparison to control eyes. This reduction in RNFL thickness was more marked over time. The amplitude of P100 was significantly decreased in MS eyes with optic neuritis in comparison to controls (p < 0.0001) and there was a statistically significant delay in peak time of P100 in MS eyes with optic neuritis versus the eyes of normal subjects (p < 0.0001), which improved over time.Conclusion: The present study suggests that there is a progressive decrease in RNFL over time in eyes with optic neuritis associated with MS. The amplitude and latency of P100 in VEP examination returned to normal ranges over time.

Normalisation of the visual evoked potential (VEP) in patients with optic neuritis (ON) appears to be a rare phenomenon. However, although several workers have indicated that it can happen, they have not followed up with subsequent VEP tests to confirm how long the VEP latency of the affected eye remains in the normal range. To resolve this, 18 patients with a clinical diagnosis of acute unilateral ON were followed for 5 years with repeated VEP tests to determine if the latency of the P2 wave from affected eye could return to the normal range. Furthermore, in cases where the latency returned to normal, the length of time that it remained so was also assessed. The normal range for the latency of the P2 wave was determined by measuring VEPs from a group of 18 healthy control subjects with a similar age distribution to the patients. This established an upper limit of 115.9 ms. At presentation the mean P2 latency of the affected eyes of the patients was 140 ms with a standard deviation of 16 ms. In general, the VEP latencies remained constant over the period of the investigation. However two patients demonstrated a return to normal latencies but this was only temporary. Their latencies become prolonged again within 2 years. These results provide evidence that the delayed P2 latency observed in patients with ON can return to the normal range in a small percentage of cases. However, this improvement may spontaneously deteriorateonce more as a result of further episodes of subacute demyelination.

Visual evoked potentials in children prenatally exposed to methylmercury

ABSTRACT.We present a case in which pupillary asymmetry produced latency changes in the visual evoked potential (VEP), leading to an erroneous diagnosis of a demyelinating optic nerve lesion. The latency asymmetry disappeared when the small pupil was iatrogenically dilated. This finding underscores the importance of pupil size on the VEP latency. Increased awareness of the inverse relationship between pupillary diameter and VEP latency will help to avoid diagnostic pitfalls and potentially unnecessary procedures.

2100-MHz electromagnetic fields have different effects on visual evoked potentials and oxidant/antioxidant status depending on exposure duration

Chapter 34 - Visually evoked potentials

The aim is to study chromatic visual evoked potentials (VEP) to isoluminant red-green (R-G) stimulus in schoolchildren. Sixty children (7-19 years) with normal color vision were examined, 30 binocularly and 30 monocularly. The isoluminant point was determined for each child subjectively by using heterochromatic flicker photometry, and objectively from recordings. The stimulus was a 7 degrees circle composed of horizontal sinusoidal gratings, with spatial frequency 2 cycles/degrees and 90% contrast, presented in onset-offset mode. VEP were recorded from Oz (mid-occipital) position. Age-dependent waveform changes and changes of the positive and negative wave were studied to both binocular and monocular R-G stimulation. Age-dependent waveform changes were observed to binocular and monocular R-G stimulation. In younger children the positive wave was prominent, whereas in older children also the negative wave became more evident. The latency of the positive wave decreased linearly with age to R-G binocular stimulation. To monocular stimulation no significant changes of the latency were observed. The amplitude of the positive wave dropped exponentially with age to binocular and monocular stimulation. The latency of the negative wave increased linearly with age to binocular and monocular stimulation, whereas the amplitude did not show age-dependent changes. These findings suggest that the chromatic VEP response undergoes evident age-dependent changes during the school-age period.

Background: Over the last few years there has been growing interest in use of visual measures as useful tools for multiple sclerosis (MS) prognosis and tracking. Optic neuritis (ON) being a prevalent and often-presenting symptom of the disease, as well as the high occurrence rate of posterior visual system damage independent of ON (optic radiation lesions), make the visual system a prime candidate for such endeavors. However, while the visual system makes for a convenient model in early stages of MS, processes which may be true in those stages may drastically change as the disease progresses, due to accumulated disease load. Here, we examine whether vision-related tools reflect demyelinative and axonal damage of the visual pathways and may be used for assessment in the clinical setup in progressive multiple sclerosis (MS) patients, in whom disease load may alter the early stage picture.Methods: Forty-eight progressive MS patients, with and without prior optic neuritis (ON), underwent a battery of behavioral tests, visual evoked potential (VEP) tests, optical coherence tomography (OCT), and structural MRI scans, at two time-points. Data were analyzed for stability between visits and for correlation between behavioral and electrophysiological data.Results: All measures were stable between visits. Significant differences were found in all measures between the affected and fellow eyes of ON patients and in VEP latencies between the affected and non-ON eyes. Motion perception differentially correlated with latencies of both ON eyes and with the non-ON eyes. Retinal nerve fiber layer thickness correlated with the latencies of non-ON eyes but not of either ON eye. No difference in lesion load was found between the ON and non-ON patients.Conclusions: ON still leaves its mark in the patient's visual system over time, with all visual measures of the affected eyes notably reduced compared to fellow eyes. Motion perception, reflecting myelination level along the visual pathway, shows its usefulness also in progressive MS. In the non-ON eyes, axonal loss appears to explain prolonged latencies, unlike in ON eyes, where demyelination appears to be the main mechanism. Lastly, the visual measures assessed herein are applicable as valid assessment tools in therapeutic studies.