Sensitivity of eye movement registration and visual evoked potentials in evaluation of therapy in patients with multiple sclerosis

Bedside tested ocular motor disorders in multiple sclerosis patients

Background/Aims. Ocular motor disorders (OMDs) are a common feature of multiple sclerosis (MS). In clinical practice, if not reported by patients, OMDs are often underdiagnosed and their prevalence is underestimated. Methods. We studied 163 patients (125 women, 76.7%, 38 men, 23.3%; median age 45.0 years; median disease duration 10 years; median EDSS 3.5) with definite MS (n = 150, 92%) or clinically isolated syndrome (n = 13, 8%) who underwent a thorough clinical examination of eye movements. Data on localization of previous relapses, MS subtype, and MRI findings were collected and analyzed. Results. Overall, 111/163 (68.1%) patients showed at least one abnormality of eye movement. Most frequent OMDs were impaired smooth pursuit (42.3%), saccadic dysmetria (41.7%), unilateral internuclear ophthalmoplegia (14.7%), slowing of saccades (14.7%), skew deviation (13.5%), and gaze evoked nystagmus (13.5%). Patients with OMDs had more severe disability (P = 0.0005) and showed more frequently infratentorial MRI lesions (P = 0.004). Localization of previous relapses was not associated with presence of OMDs. Conclusion. OMDs are frequent in patients with stable (no relapses) MS. A precise bedside examination of eye motility can disclose abnormalities that imply the presence of subclinical MS lesions and may have a substantial impact on definition of the diagnosis and on management of MS patients.

Pursuit ocular movements in multiple sclerosis: a video-based eye-tracking study

Multiple sclerosis (MS) patients frequently develop some form of ocular motor dysfunction during the disease. In previous studies, ocular motor abnormalities were found to correlate with clinical disability and with impaired cognitive performance. The objective of this study was to assess the pursuit ocular movement (POM) frequency in relapsing-remitting (RR) and secondary progressive (SP) MS patients by using a vision-based non-intrusive eye tracker. POM frequency was significantly lower (p < 0.001) in MS patients compared to normal controls. No differences between RR and SP-MS patients and no correlation between POM and expanded disability status scale (EDSS) score were found. This exploratory study suggests that our vision-based system is a new simple non-intrusive method showing impairment of POM values in MS patients, even in the absence of association with clinical disability (EDSS). Future works on larger cohorts of MS patients might validate this eye tracking in MS clinical practice.

Sinais e sintomas associados a alterações otoneurológicas diagnoticadas ao exame vestibular computadorizado em pacientes com esclerose múltipla

OBJETIVO: Descrever os principais sintomas e sinais ao exame vestibular computadorizado em pacientes com diagnóstico de esclerose múltipla. MÉTODO:Foram examinados 30 pacientes com diagnóstico de esclerose múltipla. Analisaram-se os dados relativos à sintomatologia e achados ao exame vestibular computadorizado realizado no ambulatório de otoneurologia da Irmandade Santa Casa de Misericórdia de São Paulo, em 2003. RESULTADOS: Em relação aos sintomas relatados, observamos desequilíbrio (60%), formigamento de extremidades (43,3%), vertigem (40%), cefaléia e ansiedade (36,7%), zumbido (30%), depressão (26,7%). Ao exame vestibular encontramos alterações do nistagmo de posicionamento (6,7%), nistagmo espontâneo de olhos fechados (30%), nistagmo semi-espontâneo (13,3%), rastreio pendular (3,3%) e prova calórica (63,3%). Na conclusão do exame tivemos prevalência de síndrome vestibular periférica irritativa (60%) e síndrome central (13,4%). CONCLUÇÃO: Concluimos que a realização do exame otoneurológico torna-se imprescindível nos pacientes com esclerose múltipla devido a elevada prevalência de alterações à vectonistagmografia computadorizada e elevada prevalência de sintomas otoneurológicos.

The effects of high-dose intravenous methylprednisolone on event-related potentials in patients with multiple sclerosis

The aim of this study was to assess the effects of high-dose (i.e. 1000 mg per day) intravenous methylprednisolone (HDMP) on event-related potentials (ERPs), elicited by a standard auditory 'oddball' paradigm, in patients with clinically active multiple sclerosis. In a double-blind study design, forty-four consecutive inpatients were randomly assigned in two clinically similar groups of 22 subjects each; one treated with HDMP for five days, and other with placebo. ERPs were recorded before and after the treatment. After HDMP therapy the P3 peak latency was significantly shortened (P=0.006), while peak latencies of other waves (i.e. N1, P2, and N2) remained unchanged. On the other hand, ERPs were uninfluenced by placebo treatment. Our results suggest the beneficial effect of intravenous HDMP therapy on, at least some aspects of, cognitive processing capabilities (as assessed by the auditory ERPs) in patients with multiple sclerosis.

Weak electromagnetic fields increase the amplitude of the pattern reversal VEP response in patients with multiple sclerosis

Visual evoked potential (VEP) studies are widely used for the diagnosis of multiple sclerosis (MS) and are also useful in monitoring the effects of various therapeutic modalities in the disease. Brief, extracerebral applications of picotesla (pT) range flux intensity electromagnetic fields (EMFs) of low frequency have been shown efficacious in the treatment of motor and cognitive symptoms in MS implying that this treatment modality improves action potential transmission in demyelinating pathways. This report documents three MS patients with a remitting-progressive course in whom two successive brief extracerebral applications of pT range EMFs caused an immediate increase (and normalization) of the amplitudes of the visual evoked response in the eye previously affected by optic neuritis. However, the pretreatment prolonged latencies of the evoked responses remained essentially unchanged after the administration of EMFs. Since the latency of the VEP reflects the degree of conduction velocity and the amplitude the degree of conduction block in demyelinating optic pathways, the report demonstrates that extracerebral applications of these EMFs may rapidly reverse conduction block in demyelinating fibers. Reversal of the conduction block, which is though to be related to changes in axonal Na+ and K+ channels and synaptic neurotransmitter release, accounts for the immediate improvement of vision and other neurological deficits observed in MS patients following exposure to these EMFs.

4-Aminopyridine induces functional improvement in multiple sclerosis patients: a neurophysiological study

This study reports on the neurophysiological measurements that were performed in the context of a randomized, double-blind, placebo-controlled, cross-over study with intravenously administered 4-aminopyridine (4-AP) in 70 patients with definite multiple sclerosis (MS). A beneficial effect of 4-AP was found for both visual evoked response and eye movement registration parameters. This study extends the experimental data obtained on animal nerve fibers, showing that 4-AP can improve impulse conduction in demyelinated nerve, to clinical data which indicate that 4-AP induces an objective improvement in the central nervous system function in MS-patients. It thereby also provides a theoretical basis for clinical efficacy of 4-AP in MS.

The effect of 4-aminopyridine on clinical signs in multiple sclerosis: a randomized, placebo-controlled, double-blind, cross-over study

To find out whether treatment with 4-aminopyridine is beneficial in multiple sclerosis (MS), 70 patients with definite MS entered into a randomized, double-blind, placebo-controlled, cross-over trial in which they were treated with 4-aminopyridine and placebo for 12 weeks each (maximum dose, 0.5 mg/kg of body weight). The estimated effect of the treatment as measured with the Kurtzke expanded disability status scale, which was the main evaluation parameter, was 0.28 point (p = 0.001). A significant decrease in the scale score (1.0 point or more) was encountered in 10 patients (16.4%) during oral treatment with 4-aminopyridine whereas it was not seen during placebo treatment (p less than 0.05). A significant subjective improvement (defined as an improvement that significantly affected the activities of normal daily life) was indicated by 18 patients (29.5%) during 4-aminopyridine treatment and by 1 patient (1.6%) during placebo treatment (p less than 0.05). Significant improvements related to 4-aminopyridine occurred in a number of neurophysiological parameters. No serious side effects were encountered. However, subjective side effects such as paresthesias, dizziness, and light-headedness were frequently reported during 4-aminopyridine treatment. Analysis of subgroups revealed that there was no difference in efficacy between those patients randomized to receive 4-aminopyridine and then placebo and those randomized to receive placebo and then 4-aminopyridine or between patients with and those without subjective side effects. Especially patients with temperature-sensitive symptoms and patients characterized by having a longer duration of the disease and being in a progressive phase of the disease were likely to show clear clinical benefit.