Lumbar Plexus Block – Landmark Technique ( Psoas Compartment Block ) Anaesthesia Tutorial of the Week 263 18 Th June 2012

1. The following nerves arise from the lumbar plexus; a. Lateral Cutaneous Nerve of the Thigh b. Obturator nerve c. Tibial nerve d. Saphenous nerve e. Sural nerve 2. Stimulation of hamstrings or knee flexion are acceptable motor responses using the PNS prior to LA injection. 3. Complications of Lumbar Plexus block include; a. Epidural block b. Sub arachnoid/intrathecal injection c. Cardiovascular collapse d. Psoas muscle haematoma e. Renal capsular haematoma INTRODUCTION The Lumbar plexus describes the origins of 4 of the nerves supplying the lower limb (femoral, lateral cutaneous nerve of the thigh, obturator and genitofemoral) along with the ilioinguinal and illiohypogastric nerves. Blockade of the plexus has been described since the early 1970s and is a useful technique for providing analgesia of large parts of the leg. It is principally used for post-operative analgesia for major orthopaedic surgery of the hip, femur and knee. Since Winnie’s original description of the posterior approach to the lumbar plexus in 1974 there have been several alterative descriptions, which will be described and discussed in this article. Capdevilla’s description, essential a modification of Winnie’s original technique, developed from CT anatomic studies, is probably the current technique of choice. Although Winnie described an anterior approach (via the femoral nerve) to the “lumbar plexus block” (the so called 3 in 1) in 1973, subsequent studies have shown the plexus is not at all reliably blocked via injections at this site and therefore will not be discussed in this tutorial. Publication in 2002 of a large study from France raised concerns over the safety of lumbar plexus blocks as the incidence of serious complication was calculated as 80 per 10,000 compared to an overall incidence of 5 per 10,000 for regional anaesthetics. This was principally attributed to inadvertent epidural and intrathecal spread or administration of local anaesthetic drugs. However, with appropriate skills and training it remains a useful and safe technique for regional anaesthetists.