Neurogenic Pain: Can it be treated with Epidural Steroid Injections?
Most people who experience "sciatica" are really experiencing the shooting, searing sensation of neurogenic pain (pain coming from a nerve) as discussed in the previous article, "Sciatica: What is it?" As mentioned, nerve pain can affect both the arms and legs depending on whether the pinched nerve is in the neck or low back. When a nerve is pinched by a herniated disc, the nerve becomes inflamed. Thus, the most potent anti-inflammatory medications, steroids, are used to control the inflammation around the nerve and stop the nerve pain. These steroids are placed next to the nerve by a procedure called an epidural steroid injection (ESI). For the past 50 years, millions of dollars have been spent on epidurals despite the fact that these injections do not cure the problem. ESI's only temporarily provide symptom relief for nerve pain.
Sally, a young woman who has just herniated a disc, still has burning pain that goes all the way down her leg. Relentlessly, the pain has not responded to the oral anti-inflammatory medications recommended by her doctor. She is unable to sleep and unable to walk. Now, she returns to her doctor because she needs more relief. After ordering an MRI, the doctor confirms that her disc herniation is at L4-5. He recommends an epidural steroid injection to help control the inflammation and pain from the pinched nerve. She says, "Whoa doc, before you start placing needles in my back, tell me what the risks are?"
Epidural steroid injections are not without risks. Infection is the biggest risk anytime a needle is involved. The actual procedure can also cause headaches, increased pain (usually temporary) or a drop in blood pressure (dizziness). The lumbar injections have less chance of complications than the cervical injections. This fact is due to the smaller, confined space in the neck that places critical things like the spinal cord and blood vessels in close proximity to the sharp tip of the needle. Because a steroid is used, this medication has its own side effects like nausea, blood sugar abnormalities, insomnia, or flushing. So, Sally needs to weigh these risks against the potential benefits. In fact, the short term benefits of pain relief can be expected to last up to 60 days in 75% of people like Sally who have a lumbar ESI. The chances for success start to decline for people who have lumbar stenosis, have had pain longer than six months, or have had prior surgery.
Sally agrees to have the spinal injection and schedules an appointment. Because she will be mildly sedated, she needs to have her friend drive her to and from the appointment. She is at the out-patient surgery center for about two hours. Since the doctor used X-ray guidance, he is confident that the medication got in the right spot. He injected a combination of a local anesthetic (for immediate effect) and a steroid (for long term relief). She was told to take it easy for the remainder of the day and refrain from driving for the next couple of days. Within the week, she notices substantially less pain in her leg. Finally, she can get some sleep.
Can Sally expect some long-term benefits? Typically, the pain relief from an epidural steroid injection last a matter of weeks. Hopefully with the temporary relief, Sally can start a physical therapy program and modify her life enough so that the pain does not come back with such intensity. Sometimes, this temporary relief is all that is needed to start the recovery process. Because ESI's jump start the rehabilitation process, they are done despite the risks and great financial costs. However, looking beyond the temporary symptom relief is the prospect of preventing chronic pain.
Although unproven, the science behind the harmful effects of inflammation is a compelling argument to aggressively control inflammation. This chemical reaction, called inflammation, can spread like a fire and can cause permanent changes in the nervous system. These changes can lead to a sensitized, irritated nerve that will not stop sending pain signals to the brain. Like any fire, it is best to extinguish the flames before a wildfire erupts and gets out of control. Because epidural steroid injections hose the area around the nerve off with cooling medications, the inflammation is quickly contained. Catching a fire early is probably why steroid injections work best when done within the first six months from an injury. This is also why epidural steroid injections are not typically used for chronic pain. By that time, the fire is already out of control and more permanent, long-term solutions need to be implemented.
Sally returns to her doctor six weeks after her first ESI. The leg pain is back, although with a little less intensity. She would like another shot. Her doctor agrees but warns her that she can only have three injections within a six month period of time.
Unfortunately, steroid medications also have an ugly side that limits their use. Too many injections with steroids can lead to serious problems in the surrounding tissues. Ligaments and muscles become weakened by long-term exposure to steroids. Additionally, steroids can cause some serious hormonal problems in the body. Because of the temporary and limited benefits of epidural steroid injections, other types of treatments are necessary in conjunction with this quick-fix for neurogenic pain. Even with an injection, one cannot avoid the necessity for regular exercise, good nutrition, and good health. But, those things take time to relieve pain. With spinal injections, a person can buy enough time to get the slower-acting treatments in place. For now, epidural steroids will continue to be a mainstay treatment for neurogenic pain because the realized and potential benefits continue to outweigh the costs and risks.