Altered sensory nerve excitability in fibromyalgia

Abstract

Background/purpose: To investigate nerve excitability changes in patients with fibromyalgia and the correlation with clinical severity.

Methods: We enrolled 20 subjects with fibromyalgia and 22 sex and age-matched healthy subjects to receive nerve excitability test and nerve conduction study to evaluate the peripheral axonal function.

Results: In the fibromyalgia cohort, the sensory axonal excitability test revealed increased superexcitability (%) (P = 0.029) compared to healthy control. Correlational study showed a negative correlation between increased subexcitability (%) (r = -0.534, P = 0.022) with fibromyalgia impact questionnaire (FIQ) score. Computer modeling confirmed that the sensory axon excitability pattern we observed in fibromyalgia cohort was best explained by increased Barrett-Barrett conductance, which was thought to be attributed to paranodal fast K⁺ channel dysfunction.

Conclusion: The present study revealed that paranodal sensory K⁺ conductance was altered in patients with fibromyalgia. The altered conductance indicated dysfunction of paranodal fast K⁺ channels, which is known to be associated with the generation of pain.

Keywords: Fibromyalgia; Nerve excitability; Pain; Potassium channel; Superexcitability.