Widespread pain hypersensitivity and facilitated temporal summation of deep tissue pain in whiplash associated disorder: An explorative study of women

Abstract

Widespread deep tissue pain hyperalgesia was evaluated in women with chronic whiplash associated disorder (n = 25) and controls (n = 10) using computerized cuff pressure algometry and hypertonic saline infusion. A pneumatic double-chamber cuff was placed around: (i) the arm and (ii) the leg. Cuff inflation rate was constant and the pain intensity was registered continuously on a visual analogue scale (VAS); thresholds of detection and tolerance were extracted. For assessment of spatial summation the protocol was repeated with a single-chamber cuff inflated around the leg. Temporal summation of pain was assessed from the leg with constant cuff pressure stimulation at 2 different pressure intensities for 10 min. Hypertonic saline was infused in the tibialis anterior muscle. Cuff pressure pain thresholds were lower in subjects with whiplash associated disorder compared with controls (p < 0.05). Tonic pressure stimulation evoked higher maximal VAS and larger areas under the VAS curve in subjects with whiplash associated disorder compared with controls (p < 0.05). The pain threshold and tolerance were higher during single cuff than double cuff stimulation. The area under the VAS curve after intramuscular saline infusion was larger in whiplash associated disorder (p < 0.05). The results indicated widespread hyperalgesia in chronic whiplash associated disorder and facilitated temporal summation outside the primary pain area, suggesting involvement of central sensitization.