Tehran University Medical Journal

Background: Visual, brain stem auditory and somatosensory evoked potentials (EPs) have been traditional paraclinical tests to evaluate the competency of sensory tracts in multiple sclerosis (MS) patients. It seems that only one of these EPs could be sufficient, at least as a screening test. The objective of this paper is to evaluate the frequency of these three evoked potentials in definite MS patients.

Methods: This descriptive cross-sectional study involved was 25 definite relapsing remitting MS patients who referred to our university hospital. Twenty five individuals from normal population without any neurologic, visual, auditory or sensory disorders have been evaluated as well to determine the standard values in our electrophysiology lab. Values more than mean+2.5SD for latencies and less than mean-2.5SD for amplitudes were considered as abnormal.

Results: Fifteen (60%), 13 (52%), and 13 (52%) had abnormal visual, auditory and somatosensory EPs respectively. The latency of P100 in visual EP (VEP) had the most sensitivity among all of the parameters. It was determined that the possibility of abnormality in each of auditory and somatosensory EPs in the presence of normal VEP could be 30.8%. In other words 30.8% of patients with negative VEP could have a positive auditory brain stem or somatosensory EPs.

Conclusion: In our study, a VEP abnormality was more frequent than auditory brain stem and somatosensory EPs. Thus it is not logical to perform triple EP tests in all suspected MS patients, but auditory and somatosensory EPs could be considered in patients with normal VEP.