Caudal Epidural Injection

A caudal epidural injection places medicine — usually a local anaesthetic together with a steroid — into the epidural space, the layer that surrounds the sac containing the spinal nerves. What makes it "caudal" is the route: it is given at the very bottom of the spine, through a small natural opening in the sacrum called the sacral hiatus. It is used to reach the lower lumbar and sacral nerves, for example in sciatica or lower back and leg pain, and it can serve both to relieve symptoms and, at times, to help work out where pain is coming from.

The epidural space runs the length of the spine around the nerves. By entering it low down through the sacral hiatus, medicine can be delivered to bathe the lower nerve roots. The steroid works to calm inflammation around an irritated nerve, while the local anaesthetic provides more immediate, temporary relief. Because the sacral hiatus is a reliable, easily reached entry point that sits below the main nerve sac, the caudal route is often chosen when the lower nerves are the target, or when scarring from previous surgery makes higher approaches more difficult.

The injection is done in a clean, controlled setting, usually with X-ray screening (and often a little contrast dye) to confirm the needle is in the right place. You typically lie face down. The skin over the base of the spine is numbed, and you may feel pressure or a brief ache as the injection is given; the procedure itself takes only a few minutes. Afterwards you may notice temporary numbness or heaviness in the legs as the anaesthetic works, and any steroid benefit tends to build over the following days. You will be given after-care advice and may need someone to take you home.

A caudal epidural offers a dependable way to deliver medicine to the lower nerve roots, and it is particularly useful when higher approaches are difficult, such as after previous lumbar surgery. Alongside its role in relieving nerve-related leg and back pain, the pattern of response can add to the overall picture of where a person's symptoms are arising. As with all these procedures, it is one part of an assessment interpreted by the specialist alongside scans, symptoms and examination.

• —NICE — Low Back Pain and Sciatica in Over 16s (NG59)
• —Faculty of Pain Medicine, Royal College of Anaesthetists — Standards
• —British Association of Spine Surgeons (BASS)

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.