Multimodality evoked potentials and neurological phenomenology in patients with multiple sclerosis and potentially related conditions

A comparative study of evoked potential recordings and neurological phenomenology was performed in 151 patients. The material included 95 subjects with MS, myelopathy of unverifiable etiology or optic neuritis. Multimodality evoked potentials (VEP, BAEP, median and tibial nerve SEP) and clinical data were evaluated independently. The highest rates (86-98%) of evoked potential abnormalities were found in patients with MS (clinically definite or probable) and myelopathies. More than one pathological evoked potential modality occurred in 47-69% of these subjects. Tibial nerve SEP yielded the highest frequency of abnormalities. The occurrences of silent lesions and missed lesions (i.e. normal evoked potentials in spite of clinical manifestations) were investigated for the various evoked potential modalities. Silent lesions were detected in 50-68% of the MS and myelopathy patients; SEP and VEP exhibited similar abnormality rates for clinically unaffected pathways. Missed lesions most often occurred for BAEPs but were not uncommon for the other modalities. Further evaluation of the SEP data revealed significant differences of amplitudes between patients with missed lesion and controls.