Why carry out this study?

Pain in ankylosing spondylitis (AS) is currently considered an inflammatory pain (IP). However, it was found that some patients still had the sensation of pain even without inflammation.

Our study was to evaluate the prevalence and characteristics of neuropathic pain (NeP) in AS patients, and to investigate the difference between NeP and IP, especially in the outcome of anti-TNF treatment and the serum concentration of neurotransmitters.

What was learned from the study?

Our study showed that 37.91% of AS patients had likely or uncertain NeP. Principal component analysis (PCA) of AS pain revealed that the weight of NeP was greater than peripheral pain (PP) in the first principal component (0.703 vs. 0.639). pain-DETECT Questionnaire (PDQ) was not significantly improved after etanercept treatment (10.60 ± 6.85 vs. 9.98 ± 6.40, P = 0.0671). Serum norepinephrine concentrations in patients with positive PDQ were higher than those in patients with negative PDQ and healthy controls (HC).

NeP is an important component of AS pain. TNF inhibitors do not appear to be as effective as expected in improving AS-associated NeP. Our result suggested that interference with neurotransmitter activity may be a promising new treatment for AS-associated NeP.