Nerve identification and prevention of intraneural injection in regional anesthesia

This thesis deals with techniques to more reliably identify nervous structures and subsequently prevent intraneural injection in the practice of regional anesthesia. To identify nerves of the brachial plexus and sciatic nerve, both conventional techniques such as nerve stimulation, as well as ultrasound are described. The first chapters deal with nerve identification techniques using nerve stimulation and ultrasound. Nerve stimulation is used to reliably identify various nervous structures in the vertical infraclavicular brachial plexus block. Ultrasound is applied in the infragluteal region of the lower extremity to reliably detect sciatic nerve. The subsequent chapters concern identification and prevention of intraneural needle tip placement and outcome after intraneural injection in the practice of regional anesthesia. The aim of the individual chapters can be summarized as follows: in chapter 2, the authors provide a redirection protocol for the vertical infraclavicular block to effectively block all cords of the brachial plexus. Chapter 3 describes the identification of the infragluteal sciatic nerve using consistently visible and easy identifiable tendinous fibers in the proximal long head of biceps femoris. In chapter 4 and 5, an extensive overview is given about the sonoanatomy of the brachial plexus and the sciatic nerve. In these reviews, imaging modalities such as anatomy, histology and ultrasonography are optimally matched. In chapter 6, the authors conducted a systematic review of the relation between intraneural injection of local anesthetics and neurological sequelae. Chapters 7 and 8 describe the results of an extensive, quantitative analysis of the internal architecture of the brachial plexus and the sciatic nerve. In chapter 9, the hypothesis was tested whether nerve stimulation is reliable to distinguish between intraneural and extraneural environment in supraclavicular ultrasound-guided brachial plexus block. In chapter 10, the authors investigated the accuracy of ultrasound to detect intraneural injection after injection of small amount of dye in both brachial plexus and sciatic nerve blocks. Finally, in chapter 11, the findings of the studies presented in this thesis are discussed in light of the available data and some recommendations are given for future investigations.