Adjunctive transcranial direct current stimulation after ultrasound-guided injection is associated with improved post-stroke shoulder pain outcomes

Post-stroke shoulder pain can interfere with upper-limb rehabilitation and daily functioning. This single-center retrospective cohort study evaluated whether initiation of adjunctive transcranial direct current stimulation (tDCS) within 48 h after ultrasound-guided shoulder injection was associated with greater improvement during inpatient rehabilitation. Patients receiving adjunctive tDCS were compared with contemporaneous patients receiving injection and conventional rehabilitation without tDCS. Propensity score matching and linear mixed-effects models were used. Among 212 eligible patients, 68 received adjunctive tDCS and 144 received comparator care; matching generated 47 pairs. From T0 to T1, the model-estimated between-group difference in Visual Analog Scale change was − 1.28 points (95% CI, − 1.86 to − 0.70; p < 0.001; Hedges g, − 0.89). Corresponding differences were 2.70 points for the Upper Extremity Fugl-Meyer Assessment (95% CI, 1.78–3.62; p < 0.001) and 2.00 points for the Modified Barthel Index (95% CI, 0.45–3.55; p = 0.012). No additional between-group differences were identified in exploratory ultrasound effusion measures. Recorded events were predominantly mild; no puncture-site infection or severe allergic reaction was documented. Adjunctive tDCS exposure was associated with greater improvement in pain and function during the inpatient observation period, but sham-controlled prospective trials are required to determine treatment-specific efficacy.