Pattern Reversal Visual Evoked Potentials As A Measure Of Visual Pathway Pathology In Multiple Sclerosis
Weinstock-Guttman B, Baier M, Stockton R, Weinstock A, Justinger T, Munschauer F, Brownscheidle C, Williams J, Fisher E, Miller D, Rudick R
Mult Scler 2003 Oct;9(5):529-34
The Jacobs Neurological Institute, Baird MS Center, Buffalo, NY 14203, USA
Pattern Reversal Visual Evoked Potentials (PRVEPs) have a well-documented role in diagnosis of Multiple Sclerosis (MS), but their value as a Visual function surrogate remains controversial.
We evaluated PRVEP in 37 patients with MS who were participating in a long-term follow-up study following a Phase III trial of Interferon-beta-1a (Avonex).
Patients were examined to determine the Kurtzke Extended Disability Status Score (EDSS), Multiple Sclerosis Functional Composite (MSFC), Contrast Letter Acuity (CLA), and had Cranial MRI scans to determine Whole Brain Atrophy (BPF).
PRVEP was evaluated for P100 Latency, Amplitude, and Waveform morphology.
Two summary scores were created:
- Score A - Abnormal Latencies, Morphologies, and Amplitudes of each individual eye were added
- Score B - Abnormal Latencies, Morphologies, and Amplitude Ratio between eyes was determined
Sixteen patients in this group also had PRVEP at the time they enrolled in the clinical trial, eight years previously.
At the follow-up exam, over 75% of patients had abnormal PVEP parameters while Visual Acuity (VA) was abnormal only in 59%.
Increased PRVEP latency over the eight-year period correlated with deterioration assessed by EDSS (P = 0.006), BPF (P = 0.0001), and MSFC (P = 0.0041).
Score A was significantly correlated with EDSS, BPF, CLA, Cognitive function, and quality of life assessed with the Sickness Impact profile. No correlation was seen with the MSFC.
The results indicate that PRVEP measures MS-related pathology, and can provide not only diagnostic but also prognostic information during evaluation of MS patients.
Visual And Motor Evoked Potentials In The Course Of Multiple Sclerosis
Fuhr P, Borggrefe-Chappuis A, Schindler C, Kappos L
Brain 2001 Nov;124(Pt 11):2162-8
University of Basel, Department of Neurology, Switzerland
While Evoked Potentials are sensitive tools for diagnosing Multiple Sclerosis, little is known about their prognostic value and their role in determining the course of the disease.
To validate the Visual and Motor Evoked Potentials (VEP and MEP) as measures for the course of Multiple Sclerosis, we examined prospectively 30 patients with Relapsing/Remitting or Secondary/Progressive Multiple Sclerosis.
The Expanded Disability Status Scale (EDSS), VEP and MEP were measured at entry and after 6, 12 and 24 months. The Spearman rank correlation was used for statistical analysis.
Applying multiple regression in 15 randomized patients allowed derivation of a formula for predicting changes in EDSS score based on changes in MEP and VEP.
Validation was done by comparing the predicted with the real changes in EDSS in the other 15 patients. The number of pathological VEP and MEP results correlated at all four measurement points with the EDSS (rho > or = 0.6, P < or = 0.01).
When the latencies of VEP and MEP were combined using the sum of their Z scores, correlation with the EDSS was even more significant (rho > or = 0.6, P < 0.001).
Changes over time of ElectroPhysiological data and EDSS were also correlated (rho = 0.43, P < 0.05). Moreover, VEP and MEP at baseline correlated with the EDSS after 2 years (rho = 0.43,P = 0.03).
Reliable prediction of the course of Multiple Sclerosis for individual patients is not possible from VEP and MEP data.
However, we conclude that, for groups of patients with Secondary/Progressive or Relapsing/Remitting Multiple Sclerosis the combined testing of VEP and MEP yields numerical data that allow objective estimation of the course and prognosis of the disease.
Motor Evoked Potentials and Disability In Secondary/Progressive Multiple Sclerosis
Facchetti D, Mai R, Micheli A, Marciano N, Capra R, Gasparotti R, Poloni M
Can J Neurol Sci 1997 Nov;24(4):332-7
Salvatore Maugeri Foundation, NeuroPhysiology Service, IRCCS, Gussago, Italy
PMID# 9398981; UI# 98061331
To investigate the mechanisms underlying disability in Multiple Sclerosis (MS), 40 patients with the Relapsing/Remitting form of the disease and 13 patients with Secondary/Progressive MS underwent multimodal Evoked Potentials (EP), Motor Evoked Potential (MEP), and Spinal Motor Conduction Time evaluation.
Clinical disability was evaluated by the Expanded Disability Status Scale (EDSS) and Functional System Scales.
In Secondary/Progressive MS patients, Magnetic Resonance Imaging (MRI) was used to obtain a SemiQuantitative estimate of the total lesion load of the Brain.
Spinal Motor Conduction Time was significantly longer in:
- Secondary/Progressive MS patients than controls (p < 0.001) and
- Relapsing/Remitting MS patients (p < 0.05), but
- did not differ between Relapsing/Remitting patients and controls.
Spinal Motor Conduction Times also correlated directly with EDSS scores (p < 0.001) and Pyramidal Functional System scores (p < 0.001).
Brain Lesion Load (4960.3 +/- 3719.0 mm2) and the total number of lesions (67.7 +/- 37.0) in Secondary/Progressive MS did not correlate with disability scores.
For the following EPs, the frequencies of abnormalities were significantly higher in Secondary/Progressive MS patients than Relapsing/Remitting patients:
- Visual Evoked Potential (p < 0.05)
- SomatoSensory Evoked Potentials and Upper Limb Motor Evoked Potentials (p < 0.01)
- BrainStem Auditory Evoked Potentials, Lower Limb SomatoSensory Evoked Potentials and Lower Limb Motor Evoked Potentials (p < 0.001).
These findings suggest that Disability in Secondary/Progressive MS patients is mainly due to progressive involvement of CorticoSpinal Tract in the Spinal Cord.
Quantification Of Uhthoff's Phenomenon In Multiple Sclerosis: A Magnetic Stimulation Study
Humm AM, Beer S, Kool J, Magistris MR, Kesselring J, Rosler KM
Clin NeuroPhysiol 2004 Nov;115(11):2493-501
University of Berne, Department of Neurology, Inselspital, Freiburgstrasse, CH-3010 Bern, Switzerland
To quantify Temperature induced changes (Uhthoff's Phenomenon) in Central Motor Conduction and their relation to clinical motor deficits in 20 Multiple Sclerosis (MS) patients.
Self-assessment of vulnerability to Temperature and clinical examination were performed.
We used Motor Evoked Potentials to measure Central Motor Conduction Time (CMCT) and applied the Triple Stimulation Technique (TST) to assess Conduction Failure.
The TST allows an accurate quantification of the proportion of conducting Central Motor Neurons, expressed by the TST Amplitude Ratio (TST-AR).
Temperature induced changes of TST-AR were significantly more marked in patients with prolonged CMCT (P=0.037). There was a significant linear correlation between changes of TST-AR and Walking Velocity (P=0.0002).
Relationships were found between pronounced subjective vulnerability to temperature and:
- Abnormal CMCT (P=0.02)
- Temperature induced changes in TST-AR (P=0.04)
- Temperature induced changes in walking velocity (P=0.04)
- CMCT remained virtually unchanged by Temperature modification
Uhthoff Phenomena in the Motor System are due to varying degrees of Conduction Block and associated with prolonged CMCT. In contrast to Conduction Block, CMCT is not importantly affected by Temperature.
This is the first study quantifying the Uhthoff's Phenomenon in the Pyramidal Tract of MS patients.
The results suggest that patients with Central Conduction slowing are particularly vulnerable to develop Temperature-dependent Central Motor Conduction Blocks.