Background and Aims Ultrasound guided interscalene block (ISB) is a commonly performed block for shoulder and humerus surgery. Though it provides excellent analgesia, it is associated with hemidiaphragmatic paralysis and dyspnoea. Superior trunk block (ST) has been described wherein the local anaesthetic is deposited around the superior trunk (formed by fusion of C5, C6 nerve roots). The aim of this study was to determine if ST block provides similar analgesic efficacy with lesser incidence of diaphragmatic paresis in patients undergoing proximal humerus surgeries.

Methods A total of 65 patients scheduled to undergo proximal or mid shaft humerus surgery were randomised into 2 groups. Patients in group I received Superior Trunk (ST) block while those in group II received ISB block. Both the groups received 15 ml of 0.5% bupivacaine. Diaphragmatic excursion was noted at baseline and after 30 minutes after the block. Postoperatively numerical rating scale (NRS) and requirement of opioids was documented.

Results The incidence of paresis was statistically less in ST group. No patient in ST group had complete paresis, while 11 patients in ISB group suffered the same. Partial paresis was seen in 62% patient in ISB and 19% in ST block. The percentage reduction of movement was higher in ISB group vs ST group.( 0.72 +/- 0.091 vs 0.21 +/- 0.094) . There was no difference in pain scores or the amount of opioid consumption in both groups.

Conclusions Superior trunk block provides similar analgesia comparable to the interscalene block for proximal/mid humerus surgery with preservation of diaphragmatic function.