Use of Evoked Potentials for Diagnosis of Multiple Sclerosis

Trigeminal somatosensory evoked potentials in multiple sclerosis: a case report

Somatosensory evoked potentials elicited by trigeminal nerve stimulation (TSEPs) allow the study of the trigeminal system, its peripheral to its central portion. As a routine clinical testing procedure, however, this method has not yet received greater attention and still has to wait to become a part of the diagnostic workup in multiple sclerosis (MS). A patient diagnosed as MS was presented with selective involvement of the left trigeminal nerve. Neurophysiologically, the most prominent and persistent abnormalities were found in the TSEPs. The presumed diagnosis of MS was subsequently confirmed by MRI showing evidence of demyelinating disease. There has been a scarcity of references on TSEP. Our study emphasizes its usefulness and a plea is being made for the inclusion of TSEP in protocols for the diagnostic workup in patients with MS.

Diagnostic criteria for multiple sclerosis: 2005 revisions to the "McDonald Criteria"

New diagnostic criteria for multiple sclerosis integrating magnetic resonance image assessment with clinical and other paraclinical methods were introduced in 2001. The "McDonald Criteria" have been extensively assessed and used since 2001. New evidence and consensus now strengthen the role of these criteria in the multiple sclerosis diagnostic workup to demonstrate dissemination of lesions in time, to clarify the use of spinal cord lesions, and to simplify diagnosis of primary progressive disease. The 2005 Revisions to the McDonald Diagnostic Criteria for MS should simplify and speed diagnosis, whereas maintaining adequate sensitivity and specificity.

A novel electroencephalographic analysis method discriminates alcohol effects from those of other sedative/hypnotics

Here we describe a mathematical and statistical signal processing strategy termed event resolution imaging (ERI). Our principal objective was to determine if the acute intoxicating effects of ethanol on spontaneous EEG activity could be discriminated from those of other sedative/hypnotics. We employed ERI to combine and integrate standard analysis methods to learn multiple signal features of time-varying EEG signals. We recorded cortical EEG, electromyographic activity, and motor activity during intravenous administration of saline, ethanol (1.0 g/kg), chlordiazepoxide (10 mg/kg), pentobarbital (6 mg/kg), heroin (0.3 mg/kg), and methamphetamine (2 mg/kg) administered on separate days in six rats. A blind treatment of one of the drugs was readministered to validate the efficacy of ERI analysis. Significant changes in spontaneous EEG activity produced by all five drugs were detected by ERI analysis with a time resolution of 5-10 s. ERI analysis of spontaneous EEG activity also discriminated, with 90-95% accuracy, an ataxic dose of ethanol versus equivalent ataxic doses of chlordiazepoxide or pentobarbital, as well as the effects of saline, a reinforcing dose of heroin, or a locomotor activating dose of methamphetamine. ERI correctly matched the 'blind drug' as ethanol. These findings indicate that ERI analysis can detect the central nervous system effects of various psychoactive drugs and accurately discriminate the electrocortical effects of select sedative/hypnotics, with similar behavioral endpoints, but with dissimilar mechanisms of action.

Definite and suspected multiple sclerosis in children: long-term follow-up and magnetic resonance imaging findings

Twenty-five children at the ages of 3 to 18 years with an initial diagnosis of acute disseminated encephalomyelitis were followed in the Clinic of Child Neurology for a period of 2 to 8 years. In 10 children, there were data for clinically definite or laboratory-supported definite multiple sclerosis. The other 15 children in our study were considered as having suspected multiple sclerosis. Brain magnetic resonance imaging (MRI) performed in 15 children disclosed multiple hyperintense lesions on T2-weighted imaging in 13 children: 10 with definite multiple sclerosis and 3 with suspected multiple sclerosis. The clinical manifestations did not always correspond to the size and location of the MRI lesions of demyelination. Follow-up revealed normalization of the neurologic examination in 18 patients (72%) and abnormal neurologic findings in 7 patients (28%) (6 children with definite multiple sclerosis and 1 with suspected multiple sclerosis). Magnetic resonance imaging follow-up in children with definite multiple sclerosis disclosed a reduction in the size of the lesions in 3; enlargement or new lesions were established in the other 7 cases, and 2 cases were without clinical signs of new attacks. Correlation was done concerning the findings of the cerebrospinal fluid examination, transcranial magnetic stimulation, evoked potentials, computed tomography, and MRI. The role of MRI for an early diagnosis of multiple sclerosis in children is discussed. The dynamic follow-up of the pathologic changes is of prognostic significance for the course of the disease that could be a definite cessation of the process in acute disseminated encephalomyelitis cases or transition to multiple sclerosis.

Functional and neurophysiological evidence of the efficacy of trophic pharmacotherapy using an adrenocorticotrophic hormone4-9 analog in experimental allergic encephalomyelitis, an animal model of multiple sclerosis

Chronic experimental allergic encephalomyelitis (CEAE) is a well-established animal model for the human syndrome, multiple sclerosis. CEAE has striking histological, electrophysiological and clinical analogies with multiple sclerosis and is a valuable animal model for the preclinical pharmacotherapeutical development of new putative therapeutic agents. In this paper, we describe a neurotrophic repair approach in Lewis rats suffering from CEAE. The neurotrophic peptide used is a degradation resistant adrenocorticotrophic hormone4-9 analog. The development of CEAE was examined using a combination of clinical, functional and electrophysiological parameters including somatosensory and motor evoked potentials. The latencies and amplitudes of the various evoked potentials can provide quantitative, objective data regarding the involvement of different nerve tracts in CEAE and the effectiveness of the neurotrophic peptide. Repeated subcutaneous injections of the neurotrophic peptide suppressed the development of CEAE-related clinical symptoms, markedly improved motor performance and reduced the reaction time upon thermal stimulation as compared to saline-treated CEAE animals during a 17 week follow-up study. Prolonged onset latencies of corticomotor evoked potentials and peak latencies of somatosensory evoked potentials due to the demyelination were normalized upon peptide treatment. In addition, peptide treatment substantially prevented total blocking of the corticomotor pathway in CEAE-animals and reduced the attenuation of sensory evoked potentials-related peak amplitudes as compared to saline-treated animals. The functional and electrophysiological improvements observed in CEAE-animals treated with the adrenocorticotrophic hormone4-9 analog, suggest that a neurotrophic repair approach could be of great value to promote the restoration of function in a disabling demyelinating disorder.

Evoked potential findings in Behçet's disease. Brain-stem auditory, visual, and somatosensory evoked potentials in 44 patients

We studied 54 patients with Behçet's disease, 41 males and 13 females, mean age 28 years. Forty-four patients had auditory brain-stem evoked potential (BAEP) recordings, 39 had pattern reversal visual evoked potentials (VEP), 27 had median nerve somatosensory evoked potential (SEP) recordings, and 25 tibial nerve SEPs. BAEPs were abnormal in 16 patients (52%) with neurological manifestations and in 4 (31%) without, because of decreased amplitude of wave V, prolonged I-III or III-V interpeak latencies, or uncertain/absent waves III and/or V. Eleven patients (40%) with neurological symptoms and 3 patients (25%) without, had abnormal VEPs. Absent potentials, decreased amplitude, with or without prolonged P100 latency, were found in 75% of the cases, the rest had prolonged P100 latency only. Median SEPs were abnormal in 8 patients (38%) with neurological manifestations. Four patients (21%) had abnormal tibial SEPs. Decreased amplitude with or without mild slowing in central conduction was the predominant SEP abnormality. SEPs were normal in all patients without neurological symptoms. In total, 84% of patients with, and 38% of patients without, neurological symptoms had abnormalities of one or more EP modality. When used cautiously, EP studies in Behçet's disease might be helpful to separate neuro-Behçet from other disorders with similar symptomatology, to disclose subclinical CNS involvement, to evaluate and monitor CNS disease activity, and to provide objective measures of treatment response.

Conduction properties of central demyelinated and remyelinated axons, and their relation to symptom production in demyelinating disorders

The conduction properties of central demyelinated and remyelinated axons are discussed, and related to the expression of symptoms in central demyelinating disease. The mechanisms underlying the block and restoration of conduction in segmentally demyelinated axons are described, together with the range of deficits expressed by the conducting axons. These abnormalities are related to clinical relapses and remissions, and to the phenomena of weakness, fatigue, the temperature sensitivity of symptoms, and the generation of 'positive' symptoms (e.g. Uhthoff's and Lhermitte's symptoms). The potential role of circulating 'blocking factors' in the symptomatology of central demyelinating disease is examined, and some approaches are advanced for the symptomatic therapy of such diseases.

Visual evoked potentials and visual processing in stimulant drug-exposed infants

Prenatal exposure to cocaine and amphetamines has been associated with many adverse effects in infants, including neurological abnormalities. Recent evidence shows that the visual system may be useful in infancy to evaluate neurological functioning. Visual evoked potentials (VEPs) and visual recognition memory testing were carried out on eight infants with prenatal drug-exposure and eight controls, matched for ethnicity and socio-economic status. The drug-exposed infants performed significantly worse on the visual recognition test. However, there were no differences between groups on VEP testing and no correlations between tests. The results suggest that the difficulties found in visual recognition memory of drug-exposed infants are not related to neurological maturity, as measured by VEPs.

Evoked potentials in assessment and follow-up of patients with Wilson's disease

Treatment of 9 patients with Wilson's disease was prospectively studied with evoked potentials and magnetic resonance imaging (MRI). Oral penicillamine therapy led to a decrease in auditory brainstem (ABP) and somatosensory (SEP) conduction times in 6 and 4 neurologically symptomatic patients, respectively. ABP and SEP were normal in 3 other symptom-free patients. MRI showed cerebral lesions in 4 of 7 patients. Quantified indices of brain atrophy were unaffected by treatment. ABP and SEP may reveal a reversible component of the disease that cannot be detected by MRI, and may be a more sensitive measure of treatment efficacy.