Shoulder pain after stroke: prevalence, contributing factors and consequences in daily life

Abstract: Post stroke shoulder pain, PSSP, is a common type of pain after stroke, but still further knowledge of this condition is needed. An increased knowledge of prevalence, contributing factors and impact on the individual’s life could enhance the possibility to find more effective treatments and therefore more studies are needed. The overall aim of this thesis was to evaluate PSSP with a special focus on prevalence, contributing factors and consequences in daily life. In an unselected stroke population of 327 individuals, the prevalence of PSSP was 22% four months post stroke. Predictors of PSSP (paper I) were shown to be severely affected arm motor function and severe impairments according to the National Institutes of Health Stroke Scale, (NIHSS). About 70% of the individuals with impaired sensorimotor function at stroke onset and PSSP at four months had still pain one year later. Predictors for long-lasting PSSP were left-sided hemiparesis, pain frequency and decreased passive shoulder abduction (paper II). In a group of 49 individuals with mild to moderate sensorimotor impairments post stroke (24 with and 25 without PSSP) and 11 healthy controls, somatosensory abnormalities were assessed with thermal and mechanical thresholds using the Quantitative Sensory Testing (QST) method. No significant difference in QST measurements were found between the groups with and without PSSP, but both stroke groups had generally higher thermal thresholds and more extreme low or high mechanical thresholds than the healthy controls (paper III). The association between PSSP, sensorimotor function, ability to perform daily hand activities, perceived participation and life satisfaction were evaluated in 24 individuals with and 25 individuals without PSSP, all with mild to moderate sensorimotor impairments. PSSP was associated with reduced motor function, but the PSSP had a weak association with daily hand activities, perceived participation and life satisfaction (paper IV). In conclusion, this thesis has shown that PSSP is common in individuals with decreased upper extremity motor function. Left-sided hemiparesis, pain frequency and decreased passive shoulder abduction seem to predict long-lasting PSSP. In individuals with mild to moderate upper extremity paresis, somatosensory impairments seem to have only a small impact on the pain and the PSSP appears to have a small impact on their life situation.