Facilitated pronociceptive pain mechanisms in radiating back pain compared with localized back pain

Facilitated pain mechanisms and impaired pain inhibition are often found in chronic pain patients. This study compared clinical pain profiles, pain sensitivity, as well as pro-nociceptive and anti-nociceptive mechanisms in patients with localized low back pain (n=18), localized neck pain (n=17), low back and radiating leg pain (n=18), or neck and radiating arm pain (n=17). It was hypothesized that patients with radiating pain had facilitated pain mechanisms and impaired pain inhibition compared with localized pain patients. Cuff algometry was performed on the non-painful lower leg to assess pressure pain threshold (cPPT), tolerance (cPTT), temporal summation of pain (TSP: increase in pain scores to ten repeated stimulations at cPTT intensity), and conditioning pain modulation (CPM: increase in cPPT during cuff pain conditioning on the contralateral leg). Heat detection (HDT) and heat pain threshold (HPT) at the non-painful hand were also assessed. Clinical pain intensity, psychological distress, and disability were assessed with questionnaires. TSP was increased in patients with radiating back pain compared with localized back pain (P<0.03). Patients with radiating arm pain or localized low back pain demonstrated hyperalgesia to heat and pressure in non-painful body areas (P<0.05), as well as well as a facilitated clinical pain profile compared with patients with localized neck pain (P=0.03). Patients with radiating pain patterns demonstrated facilitated temporal summation suggesting differences in the underlying pain mechanisms between patients with localized back pain and radiating pain.

PERSPECTIVE: These findings have clinical implications as the underlying mechanisms in different back pain conditions may require different treatment strategies.