Non-organic back pain signs in children with amplified musculoskeletal pain involving the back.

Abstract

Background: Traditionally, back pain in childhood was presumed to be organic. However, children with amplified musculoskeletal pain syndrome (AMPS) commonly experience back pain. Our objective was to assess the frequency of non-organic back pain signs in children with amplified pain experiencing back pain and to determine if a difference existed between those with diffuse AMPS and those with localized AMPS.

Methods: Retrospective cross-sectional cohort study of children ≤ 18 years old with AMPS and back pain presenting for an initial consultation to a pediatric rheumatology subspecialty pain clinic from 2009 to 2021. Data from an existing patient registry was combined with abstracted data from the electronic medical record including demographics, clinical characteristics, and physical exam findings. We used Fisher's exact test or Wilcoxon rank-sum test, as appropriate, to compare clinical findings among patients with localized versus diffuse AMPS.

Results: At total of 334 patients with AMPS had back pain. The majority (62%) had diffuse AMPS. The most common non-organic back pain signs were failure to guard back when going from supine to sitting, presence of allodynia, and an incongruent affect. Positive straight leg raising test, and overreaction were rare. Patients with localized AMPS were more likely to have a positive straight leg raising test (P = 0.01). Patients with diffuse AMPS were more likely to have allodynia and an incongruent affect (both P < 0.01).

Conclusions: The most common non-organic back pain signs in children with AMPS involving the back include incongruent affect, allodynia, and failure to guard the back when sitting up. Almost a third had a positive passive rotation and axial loading test. A positive straight leg raising test was rare and disappeared with distraction. These tests may help establish a diagnosis of amplified pain in children with back pain.