The somatosensory evoked potentials of the tibial nerve could help differentiate between neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS), according to a new study published in the journal Multiple Sclerosis and Related Disorders

Somatosensory evoked potentials are commonly used to diagnose and follow the progression of MS and NMOSD, but it was so far not known whether somatosensory evoked potential parameters of the tibial nerve could help distinguish between the 2 conditions.

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Here, a team of researchers from Japan led by Masahiro Sonoo, MD, PhD, analyzed data from 33 patients treated in the Department of Neurology, Teikyo University School of Medicine, in Kaga, Japan, between 2005 and 2021. Of these 33 patients, 20 had NMOSD, and the remaining 13 had MS.

The researchers analyzed the z-scores of the N21–P38 interval and the P38 latency in tibial nerve somatosensory evoked potentials and found that both were significantly higher in patients with MS compared to those with NMOSD. However, when they looked into the z-scores of the P38 amplitude, the researchers saw no difference between the 2 groups of patients.

Moreover, the researchers reported that the N21–P38 interval and the P38 latency were significantly correlated with the severity of the disease only in patients with MS, while none of the tibial nerve somatosensory evoked potential parameters were associated with disease severity in patients with NMOSD.

The authors concluded that evaluating the central sensory conduction time and P38 latency in tibial nerve somatosensory evoked potentials could help differentiate between MS and NMOSD with a prolonged central sensory conduction time and P38 latency suggesting a diagnosis of MS and not NMOSD.

NMOSD is a rare chronic inflammatory disease of the central nervous system. The disease shares many features with MS but is a different entity.

Reference

Kanbayashi T, Ogawa G, Ito T, et al. Utility of the tibial nerve somatosensory evoked potentials in differentiating between neuromyelitis optica spectrum disorders and multiple sclerosis. Mult Scler Relat Disord. Published online January 5, 2023. doi:10.1016/j.msard.2023.104503