Discordance Between Ultrasonographic and Clinical Outcomes After Corticosteroid Injection in Sjögren’s Disease-Associated Carpal Tunnel Syndrome

Peripheral neuropathy constitutes a prevalent, albeit underrecognized, extraglandular manifestation of Sjögren’s disease (SjD). Carpal tunnel syndrome (CTS) commonly coexists with SjD; however, the efficacy of standard CTS treatments in this population remains insufficiently characterized. This study evaluated the clinical and biological response to local corticosteroid injection in CTS patients with and without SjD and explored factors potentially associated with treatment outcomes. Twenty patients with SjD and CTS diagnosed based on typical clinical symptoms and supportive ultrasonographic findings and 19 control subjects with idiopathic CTS underwent ultrasound-guided corticosteroid injection. Median nerve cross-sectional area (CSA), the Boston Carpal Tunnel Questionnaire (BCTQ), and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire were assessed before treatment and 4 weeks after injection. Patients with SjD additionally underwent comprehensive clinical, laboratory, neurophysiological, and patient-reported outcome assessments. Patients with SjD appeared to demonstrate a significantly greater reduction in median nerve CSA following corticosteroid injection compared with controls (mean reduction: 0.46 vs. 0.31 mm2; p = 0.006, Cohen’s d = 0.96, CI90% [0.51, 1.49]). Despite this favorable biological response, clinical improvement was significantly smaller in the SjD group. Patients without SjD exhibited greater improvement in both the BCTQ Symptom Severity Scale (p = 0.021) and Functional Status Scale (p = 0.033), whereas changes in DASH scores did not differ significantly between groups. Patients with concomitant peripheral neuropathies experienced significantly poorer BCTQ improvement than those with isolated CTS, suggesting that neurological comorbidity may contribute to treatment resistance. No significant associations were identified between treatment response and fibromyalgia status or ESSPRI domains. Among quality-of-life measures, only the SF-36 General Health domain differed significantly between neuropathy types. Patients with SjD and CTS exhibit a dissociation between structural improvement of the median nerve and subjective symptom relief after corticosteroid injection. These findings suggest that mechanisms beyond local nerve compression, including coexisting peripheral neuropathy and potentially altered pain processing, may contribute to persistent symptoms. Comprehensive neurological assessment and multidimensional outcome evaluation may improve identification of SjD patients at risk of suboptimal response to conventional CTS therapies.