Jacobsen 1996.

Methods	Single‐centre RCT
Participants	32 hands in 29 consecutive patients with idiopathic CTS (21 women, eight men, mean age 46 (24 to 59) years). 16 hands treated with ECTR, 16 hands with conventional OCTR
Interventions	2‐portal ECTR (transbursal ‐ Chow) vs OCTR
Outcomes	Follow‐up at 2 and 6 weeks and 6 months Symptom relief, total number of analgesics, 2‐point discrimination, nerve conduction test, sick leave
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information given in the manuscript
Allocation concealment (selection bias)	Unclear risk	No information given in the manuscript
Blinding of participants and personnel (performance bias) All outcomes	High risk	No information given. Participants and personnel could not be blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	No information given. Participants and personnel could not be blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	No attrition/exclusions or missing data regarding the outcomes presented
Selective reporting (reporting bias)	Unclear risk	Some of the outcomes (electrophysiological findings) were given in a narrative way, with no numbers
Other bias	Unclear risk	No information for baseline differences of the arms or financial support of the authors