Ultrasound-guided lumbar central neuraxial block

Abstract

### Key points The practice of central neuraxial block (CNB) has traditionally relied on the palpation of bony anatomical landmarks, namely the iliac crests and spinous processes, together with tactile feedback during needle insertion. However, these landmarks may be difficult to identify accurately—a problem exacerbated by altered patient anatomy, including obesity, age-related changes, and previous spinal surgery. A 2008 guideline by the National Institute for Health and Care Excellence (NICE) recommended the routine use of neuraxial ultrasound for epidural catheterization, concluding that ultrasound might help achieve correct catheter placement.1 This ultrasound-assisted approach to CNB involves performing a pre-procedural scan which helps to identify relevant landmarks and thus guide subsequent needle insertion. Over the last decade, a large body of evidence has accumulated to support the benefit of this approach. Real-time ultrasound-guided CNB (where the needle is inserted under direct and continuous ultrasound visualization), on the other hand, remains an experimental and highly complex technique which will not be discussed further. This article describes the relevant anatomy of the adult lumbar spine, the key ultrasonographic views, and a systematic approach to neuraxial ultrasound to facilitate the performance of CNB. An overview of the current evidence is also presented. The lumbar spine comprises five vertebrae (L1–L5). Each vertebra has two functional parts: a vertebral …