Funda GOK, Ismail Hakkı KORUCU, Asiye OZKAN, Resul YILMAZ, Alper KILICASLAN

Anatomical variations detected during ultrasound-guided interscalene brachial plexus block and clinical implications

Objective: Our aim was to evaluate the anatomic variations detected during ultrasound-guided interscalene brachial plexus block(US-ISB) and present their clinical implications.Materials and Methods: After the ethical approval for the study was obtained from the local ethics committee, the files and US recordsof patients who underwent US-ISB for anesthesia of the shoulder surgery were retrospectively analyzed.Results: Anatomical variations which were considered to affect the block technique were detected in 13 (11.8%) of 110 patients. C5cervical root pierced the anterior scalene muscle (ASM) in 4.5%, and ventral rami of C5 and/or C6 were located in ASM in 3.6% ofpatients. There was a muscle bridge between C5 to C6 and C5 to C7 roots in 1.8% of the patients. The brachial plexus was locatedmedial to ASM and missing from interscalene groove in 1.8% of patients. In one case (C5 root was located in ASM), US-ISB resultedin incomplete brachial plexus anesthesia, and so general anesthesia (GA) was performed.Conclusion: Some of the brachial plexus variations in the interscalene area may be associated with further needle manipulation/redirection and block failure. We consider that prospective studies including more populations are needed to elucidate the effects ofthese variations on block parameters.

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