The ultrasound-guided selective nerve block in the upper arm: an approach of retaining the motor function in elbow

Proximal brachial plexus blocks can lead to an extended period of motor paralysis and delay the return of motor function. This could influence patient satisfaction, and extend hospitalizations. The aim of the study is to compare a selective distal nerve block of the arm to a proximal axillary block, both ultrasound-guided, in terms of their motor block intensity of the elbow. Our hypothesis is that a selective nerve block of the arm would result in a different motor block of the elbow, compared to the axillary block.

A sample size of 24 patients who were undergoing elective surgery (ASA I-III) of the wrist, hand or forearm was randomly divided into two groups: Arm Group (n = 12) and Axillary Group (n = 12). The Arm Group received ultrasound-guided block of the median, ulnar, and medial antebrachial cutaneous nerves at the level of upper-median 1/3 of the arm, and a block of the radial and musculocutaneous nerves at the level of low-median 1/3 of the arm, while the Axillary Group received ultrasound-guided axillary brachial plexus blocks. Both blocks used in combination with general anesthesia.

Our results demonstrated that the incidence of motor block at the elbow in the Arm Group was lower than in the Axillary Group. Compared with the Axillary Group, the duration of motor block at the elbow and the onset time of sensory block in the Arm Group were shortened. The patient satisfaction was increased in the Arm Group. There were no differences in the duration of the sensory block, the effect on postoperative analgesia, or in the duration of the motor block at the shoulder between both groups.

Our study showed that ultrasound-guided selective nerve block in the upper arm allowed improved retention of motor function at the elbow compared to axillary block. Secondarily, the ultrasound-guided selective nerve block seemed to provide similar analgesia after surgery of the hand or forearm with an enhanced patient satisfaction.

Chinese Clinical Trial Registry, ChiCTR-IOR-16008769 . Registered 3 July 2016.