Significance and clinical suggestions for the Somatosensory Evoked Potentials increased in amplitude revealed by a large sample of neurological patients

ABSTRACT Objectives To investigate the relationship between N20-P25 peak-to-peak amplitude (N20p-P25p) of Somatosensory Evoked Potentials (SEPs) and the occurrence of abnormalities of the peripheral and/or central sensory pathways and of myoclonus/epilepsy, in 308 patients with increased SEPs amplitude from upper limbs stimulation Methods We compared cortical response (N20p-P25p) in different groups of patients identified by demographic, clinical and neurophysiological factors and performed a cluster analysis for classifying the natural occurrence of subgroups of patients. Results No significant differences of N20p-P25p were found among different age-dependent groups, and in patients with or without PNS/CNS abnormalities of sensory pathways, while myoclonic/epileptic patients showed higher N20p-P25p than other groups. Cluster analysis identified four clusters including patients with myoclonus/epilepsy, patients with central sensory abnormalities, patients with peripheral sensory abnormalities, patients with neither myoclonus nor sensory abnormalities. Conclusions Increased N20p-P25p correlated to different pathophysiological conditions: strong cortical hyperexcitability in patients with cortical myoclonus and/or epilepsy and enlarged N20p-P25p, while milder increase of N20p-P25p could be underpinned by plastic cortical changes following abnormalities of sensory pathways, or degenerative process involving the cortex. SEPs increased in amplitude cannot be considered a specific correlated for myoclonus/epilepsy, but it in several neurological disorders may represent a sign of adaptive, plastic and/or degenerative cortical changes.