Inter Scalene Block: Revisiting old technique

The technique of percutaneous brachial plexus block has persisted in many variations since first such block given by Hirsheli in 1911.[1] Both supraclavicular and infraclavicular approaches have been described. Consequent to perivascular technique (Winnie and Collins 1964), Winnie described interscalene block (ISB) in 1970.[23] Winnie's was a single deposit block which relied upon volume for its success. It is nearly 50 years that ISB has stood the test of time and has evolved from single to multiple deposits Block. In mid-90s, ultrasound guidance was first explored by anesthetists for regional anesthesia in University of Vienna.[3] As ultrasound guidance is becoming popular and is increasingly available to budding anesthetist, popularity of old technique has started waning. In this study, old technique of ISB was revisited with a view to assess its success rate with established drugs and examine if in light of ultrasound guidance, this technique has become irrelevant for anesthetist today.

A retrospective study, a survey with high response rate, was done on success rate of three variations of old technique of ISB in 100 patients. In variation-1, thirty patients received two deposits of local anesthetic in interscalene groove. In variation-2, thirty patients received four deposits of local anesthetic in interscalene groove. In variation-3, forty patients received six deposits of local anesthetic in interscalene groove along with infiltration of both scalene muscles. In none of the variations, paraesthesia was sought or peripheral nerve stimulator (PNS) or imaging gadget was used. Demographic data in three variations were compared statistically using Chi-square and one-way ANOVA test. Success rate among variations was analyzed by Fisher's exact test.

In variation-1, 17 out of 30, in variation-2, 23 out of 30, and in variation-3, 37 out of 40 blocks were successful.

Success of ISB given without PNS or ultrasound guidance is directly proportional to the number of deposits of local anesthetic made in interscalene groove.