Generalized deep‐tissue hyperalgesia in patients with chronic low‐back pain

TLDR

Chronic painful conditions such as fibromyalgia, whiplash, endometriosis, and irritable bowel syndrome are associated with generalized musculoskeletal hyperalgesia. This study aimed to determine whether patients with chronic low‑back pain and MRI‑confirmed intervertebral disc herniation exhibit generalized deep‑tissue hyperalgesia. Twelve disc‑herniation patients and twelve matched controls underwent quantitative nociceptive testing of the infraspinatus and anterior tibialis muscles using mechanical pressure thresholds and hypertonic saline injections, with pain intensity recorded on a visual analogue scale. Disc‑herniation patients showed significantly higher pain intensity, longer duration, larger referral areas after saline injection, higher pain to supra‑threshold pressure, and lower pressure pain thresholds, confirming generalized deep‑tissue hyperalgesia and indicating central sensitization should be addressed in treatment.

Abstract

Abstract Some chronic painful conditions including e.g. fibromyalgia, whiplash associated disorders, endometriosis, and irritable bowel syndrome are associated with generalized musculoskeletal hyperalgesia. The aim of the present study was to determine whether generalized deep‐tissue hyperalgesia could be demonstrated in a group of patients with chronic low‐back pain with intervertebral disc herniation. Twelve patients with MRI confirmed lumbar intervertebral disc herniation and 12 age and sex matched controls were included. Subjects were exposed to quantitative nociceptive stimuli to the infraspinatus and anterior tibialis muscles. Mechanical pressure (thresholds and supra‐threshold) and injection of hypertonic saline (pain intensity, duration, distribution) were used. Pain intensity to experimental stimuli was assessed on a visual analogue scale (VAS). Patients demonstrated significantly higher pain intensity (VAS), duration, and larger areas of pain referral following saline injection in both infraspinatus and tibialis anterior. The patients rated significantly higher pain intensity to supra‐threshold mechanical pressure stimulation in both muscles. In patients, the pressure pain‐threshold was lower in the anterior tibialis muscle compared to controls. In conclusion, generalized deep‐tissue hyperalgesia was demonstrated in chronic low‐back pain patients with radiating pain and MRI confirmed intervertebral disc herniation, suggesting that this central sensitization should also be addressed in the pain management regimes.