Epidural steroid injections: What are they?
Epidural steroid injections are injections of medications including local anaesthetics, steroids and even opioids or hyalase (scar dissolving chemical) into the epidural space. This injection can help with the pain in your lower back, legs, and feet. You have nerves that run from the spinal cord all the way to the feet. When the disc or bony spur irritates the nerves, you can have back pain or pain that shoots to your buttocks, thighs, legs and feet. The epidural steroid injection can help in reducing the inflammation and the pain.
We can give the injection via the transforaminal, interlaminar or caudal route, depending on each patient. The target is the space between the spine and spinal cord, called the epidural space.
When should we do an epidural steroid injection?
Indications include chronic lower back pain (over 3 months in duration) and sciatica that has not improved with conservative management arising from:
- Disc herniation/Slipped disc
- Discogenic pain
- Central spinal stenosis
- Post-lumbar surgery syndrome
I rarely recommend epidural steroid injections in cases that are less than 3-6 months, as a majority of back pain and sciatica will improve by themselves. If pain is disabling and unbearable, an injection may speed up the recovery process. This allows a return to normal activities as soon as possible, thus avoiding problems of immobility such as infection, deep vein thrombosis and pressure ulcers. Do back exercises to strengthen the muscles that support the back to reduce the chance of the pain returning. Maintain a healthy weight and diet with fruits and vegetables.
How is an epidural steroid injection performed?
Before the procedure starts, you will have some sedation to calm and relax you and sometimes you may fall into a light sleep. You will then lie on your stomach on the procedure table. We will clean the skin on your back with an antiseptic solution, and you might feel a little cold. We will provide warming devices to make sure you are comfortable. I will give a local anaesthetic injection to numb the skin of the back before placing the needle.
We will use X-ray or an ultrasound to guide a thin needle through the numb area to the affected nerve root. We then inject local anaesthetic solution for immediate and short-term and a steroid injection injected for longer term pain relief. The complete process takes about 10-20 minutes depending on the number of levels. You can go home after a short period of monitoring that same day.
What approaches are there to do epidural steroid injections?
Interlaminar approach:
We insert the fine needle in between the spinous processes (those bony prominences in the middle of your back) and guided into the epidural space. This is the same approach that is used in labour epidurals for pregnant women who are about to deliver.
Transforaminal approach:
We insert a fine needle towards the opening in the spine (the foramina) where the nerves emerge out from the spinal cord. The nerve is pinched here by the disc or bony spur, making this an excellent target for treatment. This gives the best result for treating sciatica amongst the different approaches for epidural.
Caudal approach:
We can do a caudal epidural when you have had back surgery which sometimes distorts the anatomy. The disadvantage is that this method places the medication further away from the place the nerve is pinched. We can overcome this by using a catheter (a fine tubing). We target the caudal space which is an are near the tailbone. We inject local anaesthesia to numb the skin prior to placement of the larger needle; it is a sensitive area and some patients may still find it uncomfortable unless sedated.
How effective is are epidural steroid injections?
Many patients feel better about 30 minutes after the injection, but the pain may return once the local anaesthetic solution wears off. The pain relief will then improve again in 2-3 days once the steroid component of the injection starts to work. How long the pain relief lasts depends on each patient as everyone’s back pain, nerves and genetics are different, even if the problem on the MRI appears to be similar. The injection can last months to years. If the pain comes back but the injection has helped before, then the procedure can be repeated around twice a year.
What are the risks involved?
There is a very low risk of infection, bleeding and nerve damage. You may temporarily experience: numbness, weakness, delay in passing urine and nausea. Rarely the pain may worsen for a short period before improving.
What should I do after the procedure?
Continue with your normal diet and medications. If you are on blood thinners consult the pain specialist for specific advice. You can return to normal activities the next day as long as it does not involve strenuous work, jumping or anything that stresses the spine. Listen to your body and slowly increase your activity level.