Mechanisms-based classifications of musculoskeletal pain: part 3 of 3: symptoms and signs of nociceptive pain in patients with low back (± leg) pain.

Abstract

As a mechanisms-based classification of pain 'nociceptive pain' (NP) refers to pain attributable to the activation of the peripheral receptive terminals of primary afferent neurones in response to noxious chemical, mechanical or thermal stimuli. The symptoms and signs associated with clinical classifications of NP have not been extensively studied. The purpose of this study was to identify symptoms and signs associated with a clinical classification of NP in patients with low back (± leg) pain. Using a cross-sectional, between-subjects design; four hundred and sixty-four patients with low back (± leg) pain were assessed using a standardised assessment protocol after which their pain was assigned a mechanisms-based classification based on experienced clinical judgement. Clinicians then completed a clinical criteria checklist indicating the presence/absence of various symptoms and signs. A regression analysis identified a cluster of seven clinical criteria predictive of NP, including: 'Pain localised to the area of injury/dysfunction', 'Clear, proportionate mechanical/anatomical nature to aggravating and easing factors', 'Usually intermittent and sharp with movement/mechanical provocation; may be a more constant dull ache or throb at rest', and the absence of 'Pain in association with other dysesthesias', 'Night pain/disturbed sleep', 'Antalgic postures/movement patterns' and 'Pain variously described as burning, shooting, sharp or electric-shock-like'. This cluster was found to have high levels of classification accuracy (sensitivity 90.9%, 95% CI: 86.6-94.1; specificity 91.0%, 95% CI: 86.1-94.6). Pattern recognition of this empirically-derived cluster of symptoms and signs may help clinicians identify an assumed dominance of NP mechanisms in patients with low back pain disorders.