Fascial plane blocks: from microanatomy to clinical applications

Purpose of review: In the last 20 years, advancements in the understanding of fasciae have significantly transformed anaesthesia and surgery. Fascial plane blocks (FPBs) have gained popularity due to their validated safety profile and relative ease. They are used in various clinical settings for surgical and nonsurgical indications. Growing evidence suggests a link between the microscopic anatomy of fasciae and their mechanism of action. As a result, knowledge of these aspects is urgently needed to better optimise pain management. The purpose of this review is to summarise the different microscopic aspects of deep/muscular fascia to expand our understanding in the performance of FPBs. Recent findings: There is ample evidence to support the role of FPBs in pain management. However, the exact mechanism of action remains unclear. Fasciae are composed of various structural elements and display complex anatomical characteristics at the microscopic level. They include various cell types embedded within an extracellular matrix abundant in collagens and hyaluronan. Increasingly, numerous studies demonstrated their innervation that contributes to their sensory functions and their role in proprioception, motor coordination and pain perception. Lastly, the diversity of the cellular and extracellular matrix, with their viscoelastic properties, is essential to understanding the FPBs' mechanism of action. Summary: Physicians must be aware of the role of fascial microscopic anatomy and better understand their properties to perform FPBs in a conscious manner and enhance pain management.