Features of Central Sensitisation in Patients with Shoulder Pain – A Feasibility Study

Design. A case-control feasibility study, comparing people with unilateral shoulder pain and pain free controls.
Background. Previous studies have suggested that central sensitisation (CS) may be present in people with shoulder pain, mostly based on testing of nociception rather than mechanosensitivity, both of which can change as part of CS. Changes in mechanosensitivity are important for physiotherapy, which often involves nonnoxious mechanoreceptor stimulation.
Objectives. This study tested sensitivity to a range of mechanical stimuli potentially associated with CS in people with shoulder pain, compared to asymptomatic individuals. It was hypothesised that if CS was present, the response to mechanoreceptor stimulation would be increased. Methods. Both shoulders in both groups were tested for sensitivity of static and dynamic touch, vibration and punctate stimulation, plus temporal summation and pressure pain threshold (PPT). Participants completed a demographic questionnaire, pain scales, PainDETECT for neuropathic pain, and QuickDASH for upper limb function.
Results. PPT was found to be significantly lower in the affected compared to the unaffected shoulders (p<0.003), but no other statistically significant between-group differences were found.
Conclusion. This study found a lowered PPT in people with unilateral shoulder pain compared with asymptomatic individuals, but no evidence of a heightened response to other forms of mechanoreceptor stimulation. The study protocol was suitable for future studies and the required participant numbers were established. The variation in findings between studies suggests that a larger longitudinal study may be warranted.