A reliable septum exists between the lateral cord and medial and posterior cords in the costoclavicular region: Clinical and microanatomical considerations in brachial plexus anesthetic blockade

Abstract

Background and Objectives The ultrasound‐guided proximal infraclavicular costoclavicular block (PICB) appears popular but its results are inconsistent. We sought an accurate demonstration of septae formed between the brachial plexus cords. Methods We performed in‐plane, lateral‐to‐medial PICBs on 120 patients and recorded images. Once the most superficial lateral cord component was entered, a 0.4–0.6 mA current was applied to confirm needle placement; 5 ml of local anesthetic (LA) solution was then injected and its spread was observed and recorded. As the needle was advanced, the presence or absence of a hyperechoic linear structure was noted before the deeper compartment was reached, specifically looking for the possible displacement of such a septum. Results Upon initial scanning, a septum was observed in 67 of the 120 patients (46.2%). However, there was clear displacement of a linear septum between the lateral cord compartment and the medial and posterior cord compartments that prevented spread between the compartments in 94.16% of patients. Piercing the septum evoked motor responses from the medial or posterior cord. The same anatomical regions were studied microanatomically by analyzing cross‐sections obtained with the same approach angle as the ultrasound probe. Conclusions Intraplexus fascial septae that bundled the medial and posterior cords into one compartment and separated them from the lateral cord were demonstrated and confirmed microanatomically. This suggests the need for two separate injections (or two separate catheter placements for continuous peripheral nerve blockade) into the superficial and deep compartments to ensure LA spread around all three cords of the brachial plexus at this level.

Effects of double vs triple injection on block dynamics for ultrasound-guided intertruncal approach to the supraclavicular brachial plexus block in patients undergoing upper limb arteriovenous access surgery: study protocol for a double-blinded, randomized controlled trial

“…Based on the findings in Reina’s study [ 14 ], the LA is probably deposited between the epineurium of the trunks for the DI technique, which was described as the “investing adipose layers” in Siddiqui’s study [ 5 ]. However, the epineurium is usually reinforced by a closed paraneurium layer, which acts as an important tissue barrier to obstruct the spread of LA, thus delaying its block effects; similar findings have been reported in the costoclavicular space [ 15 , 16 ]. Several studies comparing sub-epineurium vs extra-epineurium injection for brachial plexus blocks have demonstrated that deliberately penetrating the epineurium rather than the internal epineurium layer is more successful, resulting in faster onset times and higher success rates with no increased incidence in complications [ 11 , 17 ].…”

Effects of the costoclavicular block versus interscalene block in patients undergoing arthroscopic shoulder surgery under monitored anesthesia care: a randomized, prospective, non-inferiority study

“…The existence of the paraneural sheath and intraplexus septum between the three cords has been reported in both cadavers and in vivo [29,30], which are believed to reduce injectate spread to the surrounding cords and toward the proximal trajectory of the brachial plexus. The paraneural sheath, visualized as a hyperechoic fascial layer surrounding the cords of the brachial plexus, may serve as part of the "axillary tunnel" for the conduit of LA spread to the supraclavicular space during CCB [31].…”

Comparison of the anesthesia effect of ultrasound-guided middle and low interscalene brachial plexus block: a randomized, controlled, non-inferiority trial

“…Two patients (5.4%) in the MISB group and three patients (7.7%) in the LISB group underwent trachea intubation and general anesthesia. The reasons may be the long distance for extending, the "compartment effect" of trunks or cords separated by blood vessels or muscle slip, the septum between the lateral cord and medial and posterior cords, and additional communicating branches between the components of the brachial plexus [24][25][26][27][28][29]. Most patients in the two groups had satisfied pain relief within 12 h. However, after that, the tramadol requirement gradually increased, which was consistent with previous studies in arthroscopic shoulder surgery of ISB because ropivacaine was absorbed and metabolized gradually after 12 h followup [30,31].…”