Two-point discrimination and judgment of laterality in individuals with chronic unilateral non-traumatic shoulder pain.

BACKGROUND: Cortical representation of the painful body region may be disrupted in several chronic pain conditions. The two-point discrimination test (TPDT) and the Left/Right Judgement Task (LRJT) have been used to identify changes in the cortical body schema in several chronic pain conditions. However, it is unclear if these changes are present for all chronic pain mechanisms. OBJECTIVES: To investigate the integrity of the body schema of the painful shoulder in patients with chronic unilateral nociceptive shoulder pain. METHODS: The sample consisted of 52 individuals with chronic unilateral nociceptive shoulder pain. The TPDT was measured over the anterosuperior and lateral regions of both shoulders using a staircase method. Participants also performed judgment tests of shoulder and foot laterality. The comparison of the TPDT and LRJT was performed using the linear regression model with mixed effects. RESULTS: There was no difference in TPDT in the anterosuperior and lateral regions when comparing the symptomatic and asymptomatic shoulders. There was no difference in the LRJT accuracy and response time between the symptomatic and asymptomatic shoulders. No differences were observed when comparing LRJT variables from symptomatic shoulder and foot. CONCLUSION: Therefore, results do not provide clear evidence of altered body schema in chronic nociceptive unilateral shoulder pain. This suggest that alterations in body representations may depend on the primary pain mechanism.

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® 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.

From Paper to Digitalized Body Map: A Reliability Study of the Pain Area.

BACKGROUND: Computerized methods to analyze pain drawings (PDs) have been developed and may aid to measure the pain area more precisely. OBJECTIVE: The aim of this study was to verify whether examiners can reproduce the patient's PDs with acceptable reliability. METHODS: This was an intra-rater and inter-rater reliability study. The protocol consisted of 4 steps: (1) scanning of paper PDs; (2) sharing the digitalized PD images between examiners; (3) reproducing the PD images in the sketching application; and (4) calculating the pain area in pixels and percentages. We calculated intraclass correlation coefficients (ICCs; 2,1), the standard error of the measurement (SEM), and the smallest detectable difference (SDD). RESULTS: Reliability was tested using 31 PDs from 17 patients in our database (11 female [64.7%], mean age: 53.23 ± 11.57 years). Intra-rater reliability varied from ICC (2,1) = 0.991 (95% confidence interval [CI] = 0.982 to 0.996; SEM = 3,432.45; SDD = 162.39 pixels; P < 0.001) to ICC (2,1) = 0.992 (95% CI = 0.978 to 0.997; SEM = 3,412.96; SDD = 161.93 pixels; P < 0.001). Inter-rater reliability for the measurement between all examiners was considered excellent (ICC [2,1] = 0.976; 95% CI = 0.956 to 0.987; SEM =8,580.75; SDD = 256.76 pixels; P < 0.001), being higher between Examiners A and C (ICC [2,1] = 0.970; 95% CI = 0.936 to 0.986; SEM = 6,453.34; SDD = 222.67 pixels; P < 0.001). CONCLUSION: Our results show that intra- and inter-rater reliabilities were excellent when an examiner reproduced the paper PDs into digitalized PDs. This process gives clinicians and researchers the opportunity to analyze pain extent more precisely using a computerized method.