Background and objectives Circumferential (C) spread of local anesthetic around the nerve is recommended for a successful nerve block. We tested the hypothesis that C spread produces a more complete block than non-circumferential (NC) spread.
Methods We randomized 124 patients undergoing open carpal tunnel syndrome surgery to receive C or NC spread ultrasound-guided median and ulnar nerve blocks. The primary outcome was the proportion of patients who developed complete sensory block measured at 5, 15 and 30 min. The loss of cold sensation was graded as: 0 (complete block), 1 (incomplete block), or 2 (no block). Secondary outcomes included motor block, nerve swelling and adverse events.
Results In group C, complete sensory block at 5 min was 2.4 (95% CI 1.0 to 5.7; p=0.04) times more frequent in the median nerve and 3.0 (95% CI 1.2 to 7.2; p=0.01) times more frequent in the ulnar nerve compared with group C. However, at 15 and 30 min, it was similar between groups. Complete motor block was more frequent in group C than in group NC for both the median nerve: 1.5 (95% CI 1.1 to 2.2; p<0.01) at 15 min, 1.1 (95% CI 1.0 to 1.2; p=0.02) at 30 min, and the ulnar nerve: 1.7 (95% CI 1.2 to 2.6; p<0.01) at 15 min, 1.2 (95% CI 1.0 to 1.4; p<0.01) at 30 min. The incidence of nerve swelling and adverse effects was similar between groups.
Conclusions C spread around the median and ulnar nerves at the level of the antecubital fossa generates more complete sensory and motor blocks compared with NC spread.
Trial registration number EudraCT 2011-002608-34 and NCT01603680
- brachial plexus
- pharmacology: local anesthetics
- nerve injury
- ultrasound in pain medicine
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Contributors PDG was responsible for the study design, data collection, execution of all regional blocks and drafting the manuscript. SL and JJ evaluated all regional blocks and supervised the manuscript. AML and XSB supervised the manuscript. All authors read and approved the final manuscript.
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 Galician Institutional Review Board, Spain (No 2011/234) and the Spanish Agency for Medicine and Health Products (reference MUH/CLIN).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. Repository name: Complexo Hospitalario Universitario A Coruña. Promoter and main researcher of this clinical trial is: Paula Diéguez García. Study code: ArAL 11.1. There is additional information available (eg, protocol, data collection notebook, informed consents, and so on).