RESUMEN
Background: Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment. One of the most devastating complications is complex regional pain syndrome. Objectivities: The aim of this study was to systematically analyze available evidence about complex regional pain syndrome after carpal tunnel syndrome surgery (CTSS), its risks, associated factors, and treatments. Material and Methods: Research conducted from 1962 through December 31, 2018, in the following databases: PubMed, Web of Science, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials. The quality assessment of the methodology followed the definitions by the Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence. The GRADE system (Grades of Recommendation, Assessment, Development, and Evaluation) was applied to evaluate the efficacy of the stellate ganglion block, one of the most cited and recurrent treatments. Results: Of the 246 studies retrieved, 44 articles were included. Concerning patients' gender, we identified a ratio of 5 females: 3 males. The mean age for women was 57.79, a standard deviation of 14.96, and for men 60.75, a standard deviation of 9.4. Considering the total of primary publications of CTSS outcomes, the accumulated incidence reached the maximum of 0.15 CRPS after CTSS patients/CTSS patients. The known risk factors for CRPS after CTSS: female gender, from the fifth decade of life, tourniquet time, immobilization and surgery on dominant hand. Conclusion: CRPS affects 2-5% of people undergoing CTSS. Its diagnosis is still a challenge and its risk factors are unclear, although it seems more likely to affect women, in the dominant hand. The most used treatments include physiotherapy and stellate ganglion block. Most patients show improvement of symptoms within one year. Further clinical trials comparing treatment modalities are required.