EDSS correlated analysis of median nerve somatosensory evoked potentials in multiple sclerosis

Median nerve somatosensory evoked potentials (SEP) were recorded in 30 pati ents with multiple sclerosis. The examined patients had an expanded disabil ity status scale (EDSS) between 0 and 6. The primary cortical potential N20 , the subcortical potentials P14, N13b, N13a and the peripheral potential P 9 were recorded simultaneously. In 5 patients normal SEP were observed (gro up 1), and in 6 patients there were consecutive disturbances of the somatos ensory pathway (group 3). In 19 patients subcortical potentials were abnorm al or absent while the following potentials were normal or identified which pattern corresponds to amplification within CNS structures (group 2). The EDSS of groups 1 and 2 were similar and lower than the EDSS of group 3, whi ch indicates that amplification mechanisms could represent a positive progn ostic factor in SEP diagnosis of multiple sclerosis.