If you are unlucky enough to suffer from a “pinched nerve,” you know it can be a painful and debilitating condition. If you have never endured an episode of back pain, perhaps you are wondering how to avoid it. This post will discuss pinched nerves, the anatomy of the spine and nervous system, and whether muscle relaxants can help recovery.
What is a pinched nerve?
A “pinched nerve” means different things to different people; therefore, it is important to define the term. Colloquially, “pinched nerve” is usually what people say when they have radiating back pain. This is usually caused by the nerves getting pinched as they exit the vertebral column.
However, nerves can become pinched in numerous locations throughout the body. For example, carpal tunnel syndrome refers to compression of the median nerve on the inside of the wrist. Likewise, the term “piriformis syndrome” describes sciatic nerve compression near the piriformis muscle near the buttocks. Though these two examples are both pinched nerves, they are not the type of pinched nerve that most people are referring to when they use the term.
For this discussion, we will consider a pinched nerve to be one that is pinched shortly after it leaves the vertebral column. Oftentimes (but not always!), a herniated disc is what puts pressure on the nerve. When this happens, it can cause radiating pain, numbness, and tingling; in severe cases, it can cause bowel and bladder dysfunction. If that happens, you want to get to the doctor ASAP to avoid long-term damage to your bowel and bladder systems.
As seen in the diagram below, nerves exit our spinal column and travel past the intervertebral disc. At the risk of oversimplifying the nervous system, it contains two parts. The central nervous system (CNS) is composed of the brain and spinal cord. This controls our movement, vital functions like breathing and controlling our heart rate, and our reflexes. The peripheral nervous system is what you see in the diagram. It consists of nerves that exit the spinal cord and are found throughout the rest of the body. The PNS has two main jobs. The first is to carry sensory information from our skin, muscles, joints, and other organs to our CNS. The second job is to control our muscles so we can move.
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An intervertebral disc separates our bony vertebrae, allowing our spines to bend, rotate, and flex. Contrary to the common myth, these discs are not much like a jelly donut at all. The outer layer of the disc is comprised of dense, fibrous connective tissue that is built to withstand the demands of high-impact activities and loading throughout a lifetime. The inner layer is composed mainly of water and provides nutrients and lubrication to the joint. The intervertebral discs are strongly connected to the adjacent verebrae by the vertebral end plate. When a disc herniation occurs, rarely does the inner layer, called the nucleus puplosus, herniate through the fibrous wall. Additionally, minor disc herniations are quite common in the general population, and many people have them without having any symptoms.
Effects of a Pinched Nerve
Unfortunately, sometimes our nerves become pinched by the disc or other nearby structures. A pinched nerve can cause radiating pain, numbness, and tingling along the pathway of that nerve. Sometimes, these symptoms are mild and they resolve quickly. Other times, they persist for a frustratingly long time.
Immediately following any injury, such as a disc herniation or a strain, the initial inflammation response can exacerbate symptoms. Over time, the inflammation decreases, and the body begins to heal; the nerve becomes less irritated. Sometimes this is enough, and the pain will disappear on its own.
First, there is an immediate signal sent to the brain that is interpreted as pain. Second, there is an invasion of different types of blood and immune cells that surround the injured site. These cells clear the area of debris and dead tissue while bringing oxygen-rich red blood cells to the area to facilitate healing. Despite the fact that this inflammation process is necessary, it can further irritate the area. Meanwhile
Meanwhile, nerve cells within the muscles surrounding the area sense danger. Because of this, they transform into a hyper-vigilant state of mild contraction. This is a protective response. The muscles are protecting the injured area while it can heal, and the body can undergo the inflammation response. Issues can arise, however, if this process goes on too long. One possibility is that the inflammation can linger longer than it is supposed to. This can cause ongoing tissue irritation and increased symptoms.
The Good News
Most disc herniations heal by themselves without surgery. However, the healing process can take a long time. We already discussed how the inflammatory response is a large cause of symptoms, and when the inflammation subsides, there is a good chance of symptom improvement. Oftentimes, an acute bout of back pain can clear up with a round of anti-inflammatories and a good stretching/strengthening program.
Muscle relaxers can help with back pain in the acute phase, but only if there are associated muscle spasms that are exacerbating the patient’s symptoms. If there aren’t any signs of spasm or muscle guarding, they are unlikely to help. As a physical therapist, I am biased towards non-pharmacological interventions. That being said, using muscle relaxers as a short-term treatment option to reduce pain and improve function can be a good idea if that is part of your plan with your primary care provider.
If you have back pain without associated muscle spasms and guarding, muscle relaxers are unlikely to help. Muscle relaxers work on the central nervous system and reduce the activity of the nervous system that is causing the muscle spasms. However, this is not a targeted approach to the issue. Meaning, the whole CNS is affected by taking these medications. Side effects include drowsiness, dizziness, fatigue, and other symptoms associated with the CNS.
As always, it is important to talk to your doctor about the best plan of care if you are suffering from radiating low back pain, and none of this information is intended to be medical advice. Until next time!
Sources:
[1] https://www.mayoclinic.org/diseases-conditions/pinched-nerve/symptoms-causes/syc-20354746