Caudal Epidural Injection
Who might benefit from an epidural injection?
If you are experiencing acute or persistent back and leg pain due to spinal nerve irritation, your consultant at Sportswise may advise that you would benefit from a caudal epidural injection alongside the other therapies mentioned in the Back Pain information page.
Several common conditions that cause severe acute or chronic low back pain and/or leg pain (sciatica) from nerve irritation can be treated by steroid injections.
These conditions include:
Lumbar disc herniation, where the nucleus of the disc pushes through the outer ring and into the spinal canal where it pressures the spinal cord and nerves.
Degenerative disc disease, where the collapse of the disc space may impinge on nerves in the lower back.
Lumbar spinal stenosis, a narrowing of the spinal canal that squeezes nerves and the spinal cord, causing significant pain.
Cysts which are in the facet joint or the nerve root and can expand to squeeze spine structures.
Annular tear, a painful condition where a tear is present in the outer layer of the disc.
For these and many other conditions that can cause low back pain and/or leg pain (sciatica), an epidural steroid injection may be an effective non-surgical treatment option.
Athletes with recurrent calf and hamstring strains may also be helped by caudal epidurals as it reduces the sensitivity of the nerves supplying these muscles.
What is an epidural injection?
An epidural injection involves injecting local anaesthetic mixed with steroid into the epidural space which encircles the dural sac. The dural sac surrounds the spinal cord, nerve roots, and cerebrospinal fluid (the fluid that the nerve roots are bathed in).
Epidural injections are considered very safe as this type of injection is given routinely to pregnant women in labour for pain relief. This is given into the low back and called a lumbar epidural.
When delivered to the base of your spine, this is called a caudal epidural injection (Caudal: from the Latin for tail). This route is less painful.
Epidural injections can be given under x-ray or CT guidance, ultrasound guidance or clinically guided. At Sportswise we use ultrasound guidance as it avoids the use of any radiation or x-ray contrast dye and is very accurate and no sedation is required for the procedure.
Who Should Not Have an Epidural Steroid Injection?
Several conditions could preclude a patient from having an injection:
Local infection around the injection site
Systemic infection – if you are unwell with a fever then the procedure should be postponed
Bleeding problems - patient taking anticoagulant medication or patients with a bleeding problem (e.g. haemophilia)
Patients who use high dose aspirin or other anti-platelet drugs which can cause bleeding should stop these medications prior to having an injection.
What does the procedure involve?
The injection is carried out in the Procedure Clinic at Sportswise. It is performed under sterile conditions. For the procedure, you will need to remove clothing down to your underwear and lie on your front with your hips overlying two pillows. Your legs and upper body will be covered for warmth. Your blood pressure will be checked and your heart rate and oxygen levels monitored throughout with a finger probe.
At the base of the Sacrum bone in the spine there is a small ‘window’ to the bony canal which allows easy access for injection through a ligament overlying this. We can see this space on ultrasound and guide a fine needle into the epidural space which lies just a few millimetres below the skin.
The skin is cleaned with antiseptic fluid and local anaesthetic is injected into the skin at the base of the spine to numb the area. Using an ultrasound scanner to guide the position of the needle (so that the needle can be seen on the screen), a thin needle is inserted at the base of the spine into the epidural space.
Once in the correct place a mixture of diluted local anaesthetic and corticosteroid are injected. We can see that the fluid is being contained within the epidural space by monitoring the flow of fluid with ultrasound Power Doppler (see video).
A feeling of pressure can sometimes be felt as the fluid is injected. Just let the doctor know and we can slow down the rate of injection and the feeling will soon pass.
Because the epidural space is confined at the bottom the fluid mixture flows upwards to bathe the nerve roots exiting from the spine.
We do not use x-ray contrast material but studies using contrast have shown that the fluid from caudal epidural injections can go up as far as the 2nd lumbar vertebra (L2).
After the procedure is completed there is a short period of observation and checks of your blood pressure. After a further 20 minutes wait you will be able to go home.
What are the potential benefits?
The injection is aimed at reducing your symptoms of pain for a period of time. The exact response to the injection varies between different patients. If the injection does help to reduce pain, it may become easier to perform rehabilitation exercises and to progress with daily activities.
The injection may be repeated if there is an improvement but incomplete resolution of symptoms, usually at 6-8 weeks after the initial injection. For some people repeated injections over the course of years can help to control their pain but each case is individual.
What are the risks?
Short term side effects include dizziness, low blood pressure, temporary leg weakness/numbness (due to local anaesthetic) and pain in the back/legs which may temporarily increase before improving. On some occasions patients do not get pain relief from the injection but we have an approximate 85% success rate for improvement.
Although the pain may improve after the injection there is still potential for it to return and caution about doing too much too soon is advised.
Potential complications of the injection include bleeding, infection, loss of feeling in the leg, allergic reaction and headache. These are not common, especially when using the caudal route of injection but it is important to be aware of these and report any ill-effects to your doctor.
The risk of infection is reported to be less than 1 in 20,000 but we have not had a problem with infection at Sportswise at all.
Some people develop facial flushing for a few days after the injection but this is harmless and soon passes.
After the injection
You should not drive for 24 hours and it is advised you should be accompanied home.If you develop a high temperature or severe pain, you should seek medical advice.
Tenderness at the needle insertion site can occur for a few hours after the procedure and can be treated by applying an ice pack for 10 to 15 minutes once or twice an hour or taking simple pain-killers like Paracetamol. In addition, patients are usually asked to rest for the remainder of the day on which they have the epidural steroid injection.
Normal activities (those that were done the week prior to the epidural injection) may typically be resumed the following day. A temporary increase in the pain can occur for several days after the injection due to the pressure of the fluid injected or due to local chemical irritation.
You will be advised at the injection clinic regarding the plan for your follow-up appointment but usually a physiotherapy review at 7-10 days.