Distal median nerve dysfunction and carpal tunnel syndrome in people with multiple sclerosis treated with teriflunomide: an electrodiagnostic study

Abstract

BACKGROUND: Trials demonstrated an increased risk of distal median nerve dysfunction (DMND) and carpal tunnel syndrome (CTS) associated with teriflunomide in people with multiple (pwMS). OBJECTIVE: To estimate the real-world prevalence of clinical CTS and electrodiagnostic DMND in teriflunomide-treated pwMS. METHODS: Cross-sectional study on selected teriflunomide (WHOATC code: L04AK02)-treated, risk factor-free pwMS at the Isfahan MS clinic in 2022. CTS was diagnosed through history and physical examination, and DMND was diagnosed by nerve conduction studies (NCS). Outcome consisted of an ordinal scale of DMND as follows: no DMND, all values within normal limits; mild, sensory conduction velocity < 40 m/s with motor onset latency < 4.5ms; moderate, motor onset latency between 4.5-6.5ms; severe, motor onset latency > 6.5ms with amplitude > 0.2mV; and very severe, motor amplitude < 0.2mV. RESULTS: 52 participants were included (median range duration of teriflunomide treatment: 3 18 years); 5.8% were diagnosed with CTS, yet, 51.9% showed at least some evidence of DMND; of the 104 hands, 25% showed mild, 11.5% moderate, 2.9% severe, and none showed very severe DMND. Right hand side (abeta SE: 0.67 0.26; p = 0.01), duration of MS (abeta SE: -0.14 0.05; p = 0.01) and age (abeta SE: 0.06 0.03; p = 0.05) were associated with a worse grade of DMND, while the association of DMND grade with sex, EDSS score, duration of teriflunomide treatment, and prior DMT, were not confirmed (all p values > 0.05). CONCLUSION: A considerable proportion of teriflunomide-treated pwMS had DMND in at least one hand. The etiology, along its optimal management strategy, remains to be explored.