The Epidural Injection (ESI) is a procedure that anesthetizes the space around the spinal sac (dural sac). This procedure may be performed at any level of the spine, although is most commonly performed in the lumbar spine or cervical spine. As opposed to a selective nerve root block, or a facet injection, which target a specific nerve or joint on one side of the spine, the ESI treats several consecutive levels on both sides of the spine. The ESI procedure delivers a low volume of concentrated medication directly into a portion of the epidural space. The ESI typically covers the epidural space of about 3 vertebral body levels.
Back pain affects nearly everyone at some point in their adult life. Often times the exact cause of pain is not readily apparent, as there are many factors which may contribute to a patient’s back pain, including disc disease, referred pain, as well as psychological factors. This can make the exact site and level responsible for the back pain more challenging to localize and diagnose. Unfortunately, while imaging studies (X-RAYs, MRI and CT scans) are helpful in screening the spine for potential causes of back pain, sometimes they don’t demonstrate an exact cause for a patient’s pain.
Back pain may arise from any anatomic structure within or around the spine which has nerve endings and is capable of transmitting pain. These structures include discs, facet joints, muscle, nerves, ligaments and dura (the membrane lining of spinal canal). All of these structures are either directly touching or in close proximity to the epidural space. Pain may be either within the spine itself (‘axial’), or radiating from the spine (‘radicular’). Both of these types of pain are ideally alleviated with the ESI.
What is the epidural space?
The membrane that covers the spinal cord and nerve roots in your spine is called the dura membrane. The space surrounding the dura is the epidural space. Nerves travel through the epidural space to your back and into your legs. Inflammation of these nerve roots may cause pain in these regions due to irritation from a damaged disc or from contact in some way with the bony structure of the spine.
What is an epidural and why is it helpful?
An epidural injection places anti-inflammatory medicine into the epidural space to decrease inflammation of the nerve roots, hopefully reducing the pain in your back or legs. The epidural injection may help the injury to heal by reducing inflammation. It may provide permanent relief or provide a period of pain relief for several months while the injury/cause of your pain is healing. Depending on the location of your pain, the epidural steroid injection can be given in the neck (cervical), middle back (thoracic) or lower back (lumbar).
What will happen to me during the procedure?
An IV may be started so that relaxation medication can be given. You will be placed lying on your stomach on the x-ray table and positioned in such a way that your doctor can best visualize your back using x-ray guidance. The skin on your back will be scrubbed using 2 types of sterile scrub (soap). Next, the physician will numb a small area of skin on your low back with numbing medicine. This medicine stings for several seconds. After the numbing medicine has been given time to be effective, your doctor will direct a small needle using x-ray guidance into the tiny bony opening (sacral hiatus) just above the crease in your buttocks. A small amount of contrast (dye) is then injected to insure proper needle position in the epidural space. If the medicine does not travel high enough to reach the affected area, a small catheter will be placed into the epidural space and advance up to the area of abnormality. Then, a mixture of numbing medicine (anesthetic) and anti-inflammatory (cortisone/steroid) will be injected.
What will happen after the procedure?
You will go back to a recovery area or may be recovered in the procedure room where you will be monitored for 15-30 minutes. You will then record the relief you experience during the next week. You will also be given a follow-up appointment for a repeat block if indicated. These injections are usually done in a series of three(3), about one to three weeks apart. You may not be able to drive the day of your procedure. Your legs may feel weak or numb for a few hours, but your weakness should quickly resolve. If it does not, please go to the nearest ER.
General Pre/Post Instructions
You should eat a light meal within a few hours before your procedure. If you are an insulin dependent diabetic, do not change your normal eating pattern prior to the procedure. Please take your routine medications (i.e. high blood pressure and diabetic medications). If you are on Coumadin, Heparin, Plavix or any other blood thinners (including Aspirin), or the diabetic medication Glucophage you must notify this office so the timing of these medications can be explained. You may need to bring a driver with you. You may return to your normal activities the day after the procedure, including returning to work. Drink plenty of clear liquids after the procedure to help remove the dye from the kidneys.
The discomfort generated during the epidural procedure may take several days to subside, and your physician may prescribe pain medication. During the healing process it is important to treat your back with care. Your physician will provide you with activity and physical rehabilitation guidelines. You will be required to do a special physical therapy and rehabilitation program for several weeks after your procedure. A special back support may be necessary as well as electrical stimulation to lessen spasms. You should be able to resume regular activity four hours after your procedure. You may have to undergo a nerve conduction study and EMG to help determine the severity and duration of back injury.
You may experience an increase in your usual pain including muscle soreness in your back where the needles were inserted. Use ice packs three or four times a day and take your usual pain medications. Do not apply heat or soak in water (i.e. tub, pool, jacuzzi, etc.) for the remainder of the day.
Duration of Relief
Most patients will have 2-3 months of relief of some of their complaints. This can range from no relief to near absolute relief with the duration being from days to many months. Some patients may not get any relief with the first injection but after one or two more done over the following weeks. Many physicians will do these injections in cycles (series) where they will do one, two or three epidural injections over a couple of weeks. The interval between these cycles should be somewhere between two to three months. More frequent administration of steroids could lead to more serious side effects. Transforaminal epidural steroid injection series will often last for 4-6 months or even longer.