Caudal Epidural Injection

Introduction

Caudal epidural injections have been employed for the relief of back pain and sciatica since around 1903 although initial injections employed local anaesthetic on a sole basis. In 1950s steroid preparations such as hydrocortisone were added to the injectate and in 1970s newer preparations called “Depo steroids” were employed for their long duration of action and have continued to be used safely. The principal indication for a steroidal caudal epidural is that of prolapsed intervertebral disc causing nerve root pain i.e. sciatica.

Anatomy

An epidural injection involves the delivery of a volume of local anaesthetic, normal saline and steroid into the epidural space. This fluid can be delivered employing a variety of different approaches i.e. the caudal approach, the lumbar or thoracic approaches. Clearly the site of a disc herniation will determine the level at which the mixture of steroid and anaesthetic is delivered to maximise the effect of the steroid. Once in the epidural space the steroid has to reach the site of the pathological process to exert its anti-inflammatory effect.

Indications for an epidural injection

The principal indication for an epidural injection is sciatica. Sciatica is nerve pain perceived distal to the knee with associated signs of nerve root compression such as weakness of the muscles, loss of reflexes or signs of sensory deficit such as numbness. In most cases the site of nerve compression will be identified by magnetic resonance imaging (MRI) scanning.

A number of conditions preclude the use of an epidural injection. This technique is absolutely contraindicated if there is an infection near or at the site of proposed injection or if the patient has a systemic or generalised infection. If the patient suffers from a bleeding disorder or is on anticoagulant medication we recommend consultation with a Specialist in Haematology prior to consideration of this technique. Relative contraindications include previous spinal surgery, allergy to local anaesthetics and congestive cardiac failure.

The technique of injection

At Joint Reaction caudal epidural injections or lumbar epidural injections are usually performed with the benefit of sedation on a day case basis. The injection itself is usually simple and takes a matter of minutes but must be performed in a sterile environment such as an operating theatre to minimise the potential for infection. Occasionally where difficulty is anticipated in knee replacement such as might occur in a patient who has previously undergone surgery x-ray screening may also be employed to optimise needle placement.

Complications with this technique are extremely rare and approximately 40 million epidurals have been administered on a worldwide basis. Approximately 3% of patients endure a short-term complication such as headache or worsening of the pain. More serious complications such as sexual dysfunction and paralysis have been described in the literature but these complications are incredibly rare.

Studies of the efficacy (effectiveness) of caudal epidural injections indicate that approximately 60% of patients will undergo substantial short term benefit from epidural steroidal injections. Epidural injections are therefore ideal for providing alleviation of the severe nerve pain experienced by sciatica sufferers whilst the process of resolution of a disc prolapse occurs. They are not meant to act on a longer term basis or to “cure” the condition.

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