Stability of lumbosacral somatosensory evoked potentials in a long-term follow-up

Variability of the lumbosacral somatosensory evoked potential (LSEP) in test/retest situations was assessed in 49 patients with nonprogressive neurological disorder and 20 healthy subjects. The average time of LSEP follow-up in the patients was 16.2 months. The first group of healthy subjects had a short test/retest period of between 2 days and 2 weeks, and the second group had a long period between tests, with a mean of 35.7 months. The R and S waves of the LSEP were analyzed separately for latency and amplitude. Test/retest differences were statistically compared. The average correlation coefficient for healthy subjects was 0.84 and for patients was 0.78. These results suggested a remarkable stability of LSEPs in both healthy subjects and patients with nonprogressive neurological disorders. Therefore, we propose that LSEPs can be used in follow-up both to screen for initial dysfunction of the sensory system and to detect any changes in present dysfunction.