Tactile acuity, left/right judgment performance, motor imagery ability, and pressure-pain threshold in patients with...

Chronic pain can alter cortical pain representation, and tests like Two-Point Discrimination Test (TPDT), Left/Right Judgment Task (LRJT), motor imagery, and Pressure-Pain Threshold (PPT) can assess these changes. However, their applicability to all pain mechanisms is uncertain.

To compare the TPDT, LRJT, motor imagery ability, and PPT of chronic rotator cuff-related shoulder pain (C-RCRSP) patients with asymptomatic and pain-free controls.

Forty-eight C-RCRSP patients and 45 pain-free controls were assessed using a caliper for TPDT and the Recognize® application for LRJT. Motor ability, PPT, physical function, fear avoidance, pain catastrophizing, and Central Sensitization Inventory (CSI) were also evaluated. As part of the subgroup analysis, C-RCRSP patients were divided into two groups based on their CSI (≥40, n = 19; <40, n = 29).

C-RCRSP patients demonstrated higher TPDT thresholds [acromion (F = 5.41, p = 0.001) and deltoid (F = 26.67, p < 0.001)] but no significant differences in LRJT performance [recognition accuracy (F = 2.47, p = 0.063) and response time (F = 0.98, p = 0.414)] than pain-free controls in both shoulder joints. C-RCRSP patients had poorer motor imagery abilities (p < 0.001). The deltoid region PPT differed significantly between the groups (F = 17.45, p < 0.001), but it was not significant for the tibialis anterior region (F = 1.16, p = 0.33). C-RCRSP patients with a CSI≥40 reported higher night pain, reduced shoulder range of motion, slower response times, poorer motor imagery ability, and higher scores on pain-related questionnaires compared to those with a CSI<40 (p = 0.043-<0.001).

C-RCRSP patients demonstrated poorer tactile acuity, mechanical sensitivity, and motor imagery ability especially in those with central sensitization, which should be considered in treatment planning.