Comparative anatomical study of digital block with the WALANT, interdigital, and transthecal techniques.

Introduction: Interdigital block and transthecal block through the flexor sheath are commonly used techniques for the anesthesia of isolated fingers. The wide-awake local anesthetic no-tourniquet technique is a relatively new approach for local anesthesia during finger procedures. The anatomical spread of local anesthetics with the wide-awake local anesthetic no tourniquet technique has not been described adequately.This anatomical study aimed to assess the distribution of a local anesthetic dye solution to the digital nerves. The study was designed to compare the nerve staining effect using the wide-awake local anesthetic no tourniquet and the transthecal and interdigital techniques in cadavers. We hypothesized that the wide-awake local anesthetic no tourniquet technique stains digital nerves more effectively than the interdigital and transthecal digital injection techniques.

Methods: 14 blocks were performed using anatomical landmarks. 2 mL of a mixture of local anesthetic, methylene blue, and contrast medium were injected. Before dissection, the specimens were passed through an X-ray scanner to assess the spread of the mixture. Finally, anatomical dissections were performed to evaluate the specific hand nerve implications.

Results: In the wide-awake local anesthetic no tourniquet group, the local anesthetics spread to the nerves of each finger but not the common nerve. In the transthecal and interdigital groups, the spread extended from the common nerve to the lateral aspect of the adjacent fingers.

Conclusion: The wide-awake local anesthetic no tourniquet technique was as effective as conventional techniques in the digital blockade, achieving specific spread on the targeted nerves.