Epidural Steroid Injection
What is epidural steroid injection?
Injection of steroid in the epidural space is called epidural steroid injection.
What is the location of epidural space?
The spine is made up of small pieces of bones and there is a canal within the bones. This canal is called the spinal canal. The spinal cord runs from the brain towards the tail bone through this canal. The spinal cord has 3 thin layers of coverings called meninges. The outermost covering is called the dura. The space between the bony canal of the spine and dura is called epidural space. All nerves that start from the spinal cord, run through this epidural space and come out of the spine through the neural foramina of the spine.
Are epidural anesthesia and epidural steroid injection the same?
When a local anesthetic agent is injected inside the epidural space for giving anesthesia of cesarian section, or painless labor, or during other surgeries, it is called spinal anesthesia. When steroid and local anesthetic mixture is injected for managing different painful conditions, it is an epidural steroid injection.
How is epidural steroid injection done?
Epidural steroid injection is not like a simple intramuscular, subcutaneous or intravenous injection. In fact, epidural space is a very narrow space and the spinal cord is situated very close. So, all precautions are taken not to injure the spinal cord. Also, it must be done in operation theater maintaining all aseptic precautions. Anesthesiologists are well trained to do epidural injections.
Usually, this procedure is done under fluoroscopy or C-arm guidance. This machine is like a video X-ray. The advancement of a needle is done under direct visualization of a needle under X-ray guidance or sometimes under ultrasonography guidance.
Once we reach the target, different tests like the loss of resistance test are done to be sure that the needle is in proper position. After the physician is sure about the needle position, he or she first inject a radio-opaque contrast agent and look for the proper spread of dye. If the dye spread is not typical, the physician repositions the needle till he/she gets the typical spread of dye. After all these confirmatory tests he or she injects a mixture of medicines.
What are the complications? Is it a serious procedure?
Usually, anesthesiologists perform thousands of epidurals and it is a very safe procedure in an anesthesiologist’s hand. But there is a number of side effects or complications of epidural steroid injection. These are:
- Punture of blood vessels and formation of hematoma
- Accidental injection of medicines in a blood vessel
- Injury of spinal cord
- Injury of nerve roots
- Puncture of dura or other meningeal layers
- HPA suppression
- Rise of blood sugar
- Moon face
All these complications are rare particularly in hands of anesthesiologists.
What are the indications of an epidural steroid injection?
Epidural steroid injection is done in several painful conditions. These are:
- Slipped disc or disc prolapse or herniation of disc
- Spinal canal stenosis
- Vertebral fracture for pain reduction
- Discogenic back pain
- Complex regional pain syndrome
- Acute herpes zoster or post-herpetic pain
- Phantom limb pain
- Painless labor or painless normal delivery- here only local anesthetic is injected, the steroid is not added.
Which steroid is injected?
Most commonly depo preparation of triamcinolone or methyl prednisolone in particulate form is injected, but other non-particulate staroids like dexamethasone, betamethasone are also injected.
What are the differences between particulate and non-particulate steroid injection?
Particulate steroids have long-term effects. So benefits may be long lasting, but side effects too may last longer, if doses are exceeded. Also if a particulate steroid is injected accidentally into a blood vessel, it may occlude it and may cause ischemic damage of the nerve root or spinal cord leading to paralysis.
Whereas non-particulate steroid may have shorter duration of benefits, but is safer and chances of ischemic spinal cord or nerve injury is not there. Interventional pain physician is the best judge to decide the type of steroid needed in a particular patient.
Is there dose limitations of epidural steroid?
Earlier there were no dose limilations. Physicians used to inject 80 mg to 120 mg each times and injections were given several times. Nowadays there is recommendations that to dose should not exceed 3 mg per kg of body weight in a year and 6 mg per kg of body weight in life time.
What is the success rate of an epidural steroid injection?
Success rate depends on the indications and it goes upto 90% in disc prolapse.
What are the limitations of an epidural steroid injection?
Epidural steroid injection may not cure the condition and there might be recurrence of pain unless there is spontaneous recovery of the primary disease condition.
How long can one expect pain relief after epidural steroid injection?
After particulate steroid injection, one can expect about 2 months of pain relief. Actually, this can vary from 3 weeks to 6 months. If the disease is cured spontaneously, the pain might not recur again. In some patients, the breaking of the pain cycle can give very long-duration pain relief.
How early can an epidural steroid injection be repeated?
Repeated epidural steroid injection with particulate steroid is not recommended as it can produce a cumulative effects and may cause serious side effects like adreno-cortical axis suppression. Normally it is not repeated before 1 month unless there is severe pain and no other less risky alternative procedure is applicable.