7. Neurophysiology in diagnosis and prognosis of multiple sclerosis in age of magnetic resonance imaging

Abstract

Objective The advent of magnetic resonance imaging techniques has greatly reduced the diagnostic value of neurophysiological tests in MS, particularly evoked potentials. In disease progression, most of MS patients accumulate inflammatory lesions, axonal damage, and progressive brain atrophy, along with an increasing degree of disability. More promising is the utilization of neurophysiological tests to quantify the severity of white matter involvement. Methods Evoked potentials (EP) have been still used in multiple sclerosis (MS) especially in its early diagnosis. Recently, multimodal EPs appears to be a prognostic factor for disease progression ( Schlaeger et al., 2012 , Invernizzi et al., 2011 , Schlaeger et al., 2012 ). Deeper insights about causal and functional relationships in plasticity of the motor system in patients with MS were gained by neurophysiological techniques, predominantly by transcranial magnetic stimulation. Results Visual evoked potential (VEP) are preferentially used in early diagnosis of MS for detection of subclinical optic neuritis. Somatosensory (SEP) and motor (MEP) evoked potentials reveal subclinical lesions in the CNS and could be a supplementary diagnostic tests for sensory and motor system disturbances. MEP abnormalities correlate with the degree of motor impairment and disability. A number of functional imaging studies have assessed patterns of brain activation during simple motor tasks in MS patients and their relationship with CNS damage and motor function. Conclusion Evoked potentials are functional neurophysiological methods highly sensitive in revealing ,,silent lesions“ especially at the beginning of MS. Multimodal evoked potentials have indisputable benefit of prognostic value to determine non-responders, ,,benign“ course of the disease and identification of patients with significant disease progression. A battery of neurophysiological tests could be useful in monitoring the disease progression in individual patient and as surrogate endpoints in clinical trials. Supported by Research Project of Charles University PRVOUK P34, Czech Republic.