Variability of central conduction in the course of multiple sclerosis. Serial recordings of evoked potentials in the evaluation of therapy

In 27 normal subjects evoked potentials (EPs) were serially measured across an interval of 3.5 months. The variation in latencies of the P100 component of the VEP and of the components N13 and N20 of the SEP did not exceed 12% of the absolute values of these latencies on the first recording. The VEP and SEP were also serially recorded over the same interval in 35 patients with 'clinically definite' multiple sclerosis. Changes of the latencies exceeding those of normal subjects were noted in 30% of the cases. The changes in the EPs showed no correlation with the variations in the overall clinical disability. It is argued that EPs are probably more sensitive to changes in function of parts of the white matter than the clinical examination and are useful in the quantification of these changes. As a model for future studies, EPs were used in the 'evaluation' of ACTH therapy. It appeared, that therapy did not have effect on the EPs.