Relationship Between Sensory Dysfunction and Walking Speed in Patients With Clinically Isolated Syndrome.

Abstract

The aim of this study was to investigate a relationship between sensory dysfunction examined with somatosensory-evoked potentials of the posterior tibial nerve (tSSEP) and walking speed in patients with clinically isolated syndrome. In 120 patients (mean age 32.2 ± 8.7 years, 84 females), Expanded Disability Status Scale (EDSS), timed 25-foot walk test (T25FW), brain and spinal cord MRI, and tSSEP were performed. P40 latencies and N22a-P40 interlatencies were analyzed, and the z-score for each latency was calculated and combined into total tSSEP z-score. T25FW significantly correlated with total tSSEP z-score (rs = 0.211; P = 0.021). When looking at each component of the tSSEP separately, T25FW significantly correlated with z-scores of P40 wave latencies (rs = 0.223; P = 0.014) and N22a-P40 interlatencies (rs = 0.241; P = 0.008) of the left side. There were no significant correlations with N22a wave latencies. Patients who presented with transverse myelitis (N = 41) and patients who had spinal cord lesions on MRI (N = 53) had significantly higher total tSSEP z-score compared with other patients (0.07 vs. -0.28, P = 0.019 and -0.02 vs. -0.38 P = 0.023; respectively). Somatosensory-evoked potentials of the posterior tibial nerve z-score corrected for age, sex, cervical spinal cord MRI lesions, and total number of supratentorial T2 lesions was a statistically significant predictor for T25FW (B = 0.267, P = 0.023). Spinal somatosensory dysfunction is one of the factors associated with reduction in walking speed in early patients with multiple sclerosis. Somatosensory-evoked potentials of the posterior tibial nerve may potentially be useful in identifying patients at higher risk for the development of walking impairment in the future.