Sympatholytic Effects of High Thoracic Erector Spinae Plane Block: A Prospective Observational Study on Changes in Optic Nerve Sheath Diameter

The thoracic erector spinae plane (ESP) block is a regional anesthesia technique. This technique involves the injection of local anesthetics into the deep layers of the erector spinae muscles, blocking both somatic and visceral pain pathways. Although various studies have been conducted on the effectiveness of this technique in different clinical situations over the years, further research is needed to understand the precise mechanisms behind its neuroanatomical effects.

The stellate ganglion, an important component of the sympathetic nervous system, plays a crucial role in the regulation of several autonomic functions. It has been suggested that the ESP block may affect the stellate ganglion through its injection at the upper thoracic levels. Changes in the optic nerve sheath diameter (ONSD) have been used as an important indicator of intracranial pressure changes. Any potential changes in ONSD following stellate ganglion blockade could help elucidate the effects of the ESP block, thus aiding in the understanding of its safety and potential benefits for analgesia.

The aim of this study is to investigate the changes in optic nerve sheath diameter in patients undergoing the thoracic ESP block, which could provide more information on the impact of the ESP block on the stellate ganglion. By doing so, we aim to gain further insights into the potential analgesic effects and safety of the ESP block.