Clinical evaluation of somatosensory integrity in people with chronic shoulder pain

Purpose: Indirect evaluation tests of somatosensory integrity, such as the left/right judgment task and two-point discrimination thresholds, are used to complement a clinical evaluation facilitating tailored rehabilitation programs for patients with chronic pain. This study aimed to compare performance on the left/right judgment task and two-point shoulder discrimination thresholds between people with chronic shoulder pain and asymptomatic controls. The study's secondary objective was to investigate whether there is a relationship between pain intensity and the painful area with TPDT and LRJT. Materials and methods: It is a cross-sectional study with a control group. Volunteers participated in the left/right judgment task using the Recognise ShoulderTM app, and two-point discrimination thresholds were performed using a Mitutoyo (R) digital caliper. The extent of the painful area, affectivity, and functionality were also determined to characterize the sample. Results: We assessed 52 symptomatic and 50 asymptomatic individuals. A between-group difference was observed in time response for the left/right judgment task (p = 0.025) and the two-point discrimination thresholds when tested over the shoulder's lateral region (p = 0.012). There was a significant positive weak correlation between pain intensity and TPDT test performance over the anterior shoulder (rs = 0.35; p = 0.01) and a positive weak correlation between pain area and LRJT response time (rs = 0.26; p = 0.04). Conclusions: This study demonstrates a difference of small magnitude in the response time of the LRJT for the shoulder segment and TPDT in the lateral shoulder region between individuals with chronic shoulder pain and asymptomatic controls.