Background We aimed to investigate the prevalence of dysautonomia in complex regional pain syndrome (CRPS) via the combined autonomic nervous system (ANS) function tests, including the deep breathing test (DBT), orthostatic test (OST) and sympathetic skin response (SSR).
Method We retrospectively examined 263 patients who underwent the combined ANS tests to evaluate CRPS between August 2013 and December 2016. Based on the Budapest clinical criteria, patients were stratified into confirmed-CRPS or suspected-CRPS groups. We performed binary logistic regression analysis using the inverse probability of treatment weighting to investigate the association between the tests and CRPS. Sensitivity and specificity were calculated to assess the diagnostic performance of the ANS tests for CRPS. We compared the results of these tests between the outcomes of sympathetic nerve blocks (SNBs).
Results Among 247 patients, finally included in this study, 199 patients (80.6%) were diagnosed with CRPS. Abnormal results of overall or each ANS function test showed significant associations with CRPS, excluding OST (overall abnormality: OR 2.44, 95% CI 1.51 to 3.95; p<0.001; DBT: OR 2.57, 95% CI 1.23 to 5.38, p=0.013; OST: OR 1.88, 95% CI 0.92 to 3.84, p=0.085; SSR: OR 2.71, 95% CI 1.38 to 5.32, p=0.004). However, their prevalence in CRPS and their sensitivities for CRPS were low (overall abnormality: 26.1%; each test: <15%). No significant association existed between dysautonomia and SNB outcomes.
Conclusion Dysautonomia, as evaluated using the combined ANS tests, were observed in a small portion of patients with CRPS. The diagnostic performances of these tests for CRPS were inadequate for clinical purposes.
- complex regional pain syndromes
- diagnostic techniques and procedures
- autonomic nerve block
- chronic pain
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Contributors HL—manuscript preparation, revision and statistical analysis. KHL—data collection. JYM—study design, statistical analysis, manuscript preparation and manuscript revision. Y-CK—manuscript revision.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This retrospective study was approved by the Institutional Review Board of Seoul National University Hospital (IRB No. 2004-005-1114). The requirement for informed consent from patients was waived due to the retrospective study design.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. Data will be provided on reasonable request.