Chronic pain often has spinal level sources. The problems may be as subtle as an overly sensitive spinal level, disc degeneration, disc herniation, vertebral bone fracture, and muscle or nearby nerve irritation. Determining the exact cause may be difficult, and often a combination of factors contribute to the symptoms perceived by the patient. Structures in the spine, especially the discs and joints, can directly or indirectly irritate spinal nerves and refer pain to spinal segments. MRI scans may have small changes that look insignificant, but they are often contributing factors to pain.
Epidural injections are implemented in chronic pain management to treat conditions that may be related to the irritation of nerves controlled at the spinal level. The spine travels from the head to the pelvis, and the nerves of the spine are the wiring that connects the brain to the rest of the body. The spinal nerves and spine itself can be overly sensitive; calming them down by injection is sometimes very useful to control pain. The two most common uses for epidural injections are for surgery and pregnancy. These use only local anesthetics and sometimes opioids to control pain for hours during these short periods of time. In pain management, epidural injections are direct procedures used to control pain for long periods of time.
How It Works
Epidural injections for pain can be done at practically at any region of the spine. The exact level of intervention is determined by the problem being treated. Injections are done by many different specialists, but perhaps best practiced by a Physical Pain Specialist. The more experienced the specialist, the better the quality and success of the injection, and hopefully with the least amount of pain. Technique and skill improves over time, and some interventionalists are superior in their ability to make a scary experience comfortable.
The epidural space is a very small region of insulation consisting of fatty tissue surrounding the spinal cord and spinal nerves. It is located inside the spinal column, and the space can be approached centrally, know as an intralaminar, or from the side where the nerves exit, known as a transforaminal route. The technique used depends on the specific patient, previous surgeries, and the problem being addressed. All these procedures are done sterilely, under real time X-ray guidance, and of course, require a special needle to deliver the medication to the right place.
Depending on exactly what is being done, it usually only takes a few minutes to complete the injection. At the start of injection, the patient is usually laying face down on a special X-ray table. The skin is then cleaned with an antiseptic solution and draped sterilely to prevent infections. Using real time fluoroscopy, the correct location is identified and the skin is locally anesthetized with short-acting lidocaine. Then, using a special needle and fluoroscopy, the specialist guides the needle into the correct position for the injection. Next, a special X-ray contrast is injected to confirm needle location, followed by the injection of a long acting steroid and possibly a longer acting local anesthetic to immediately reduce pain in the region. Sometimes more than one injection several weeks apart is needed to control symptoms since only so much steroid is safe to use at any one time. For some patients, periodic injections, once every several months, is the best way to manage a chronic problem.
Every injection has risks when performed. There are generally four risks for any injection. They are:
- Risk of infection
- Risk of bleeding
- Risk of allergic reaction
- Risk of needle damage
The first risk is an infection from sticking the needle through the skin. This is controlled by cleaning off the skin. The risk of a contaminated medication now is extremely low since the Food and Drug Administration has started controlling all producers of injectable medications. The second risk is bleeding. As long as the patient is not on blood thinners, this risk is very low – About 1 in 50,000 or less. If it does occur, it can be treated surgically. The third risk is an allergy to a medication, and this usually just causes itchiness, which is also easily treated. The last risk is the needle damaging a structure around the spine or the spine itself. By doing the injection with real time X-ray, and by an experienced physician (not a NP or Physician Assistant, some practices are using these providers, ask the person) this risk can be minimized. Spinal headaches are also a risk, but again, with an experienced provider it should not occur and can be easily treated if necessary.
Epidural injections can be a very successful management strategy for pain. When done well, they are quick, effective and almost painless for most patients. Physical Medicine Pain Specialists are often some of the best physicians to see help determine the cause of pain and initiate treatment, especially when spine injections would be beneficial.
Thomas Cohn, MD
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