Does hemiplegic shoulder pain share clinical and sensory characteristics with central neuropathic pain? Acomparative study

BACKGROUND: Hemiplegic shoulder pain (HSP) is a common poststroke complication and is considered to be a chronic pain syndrome. It is negatively correlated with the functional recovery of the affected arm and the quality of life of the individual. It also leads to a longer length of stay in rehabilitation. Today, there is no consensus as to the underlying mechanism causing HSP, making the syndrome difficult to treat.AIM: The aim of this study was to compare the clinical and sensory profile of individuals with HSP to that of individuals with established central neuropathic pain (CNP) in order to identify common features and the presence of neuropathic components in HSP.DESIGN: Cross sectional controlled study.SETTINGS: Outpatient rehabilitation clinics.POPULATION: Sixteen chronic HSPpatients and 18 chronic CNPpatients with spinal cord injury (SCI-CNP).METHODS: The chronic pain characteristics, thresholds of thermal and tactile sensations and presence of pathological sensations were compared between groups, and between painful and pain free body regions within groups. Correlations were calculated between HSPintensity and sensory and musculoskeletal characteristics.RESULTS: Patients with HSPand patients with SCI-CNPhad similar decrease of thermal sensibility in the painful compared to intact body regions and both groups presented similar rates of pathological sensations in painful regions. HSPand SCI-CNPdiffered however, in the quality of pain and aggravating factors. Significant correlations were found between HSP intensity and heat-pain threshold, presence of subluxation and spasticity.CONCLUSIONS: The similarities between HSPand SCI-CNPand the altered spinothalamic function and sensitization suggest that HSPhas neuropathic components in its mechanism. Nevertheless, the unique features of HSPpoint towards additional possible mechanisms.