The pain threshold in juvenile chronic arthritis.

An algometer was used to study the pain threshold (PT) on pressure at the joint capsules of the wrists, elbows, knees, ankles and at paravertebral soft tissues in 57 patients with juvenile chronic arthritis (JCA) and 69 healthy controls, aged 6-17 yr. The PTs were correlated to visual analogue scales (VAS) and values of articular disease activity, to define their relation with pain perception and joint inflammation. The PTs in JCA patients were significantly lower than in their healthy peers, both in children with active inflammation as well as in children without detectable inflammation. The JCA group with active inflammation showed significant lower PTs than without detectable inflammation. Disease activity and VAS correlated significantly with PT (r = -0.5). There is an enhanced sensitivity to noxious stimuli in all measured body areas, suggesting a change in the pain processing system in JCA. The sensitivity endures in JCA patients without clinically active disease, probably due to prolonged central sensitization after periods of active disease.