I Have Tingling In My Leg After A Car Accident: What Can Cause This?
Tingling in the leg(s) after a car accident is one of the most commonly reported symptoms, right behind neck and low back pain. Unfortunately, the cause of these symptoms is not always cut and dry, and depending on the cause of the injury, these symptoms can range from serious to benign. In this article, I will not be discussing the specific causes of injury to the nerves. Instead, I will be discussing the 3 main types of nerve injuries that cause tingling in the legs, as well as which nerves are likely affected based on the location of the symptoms.
Anatomy of the Lower Extremity Nerves
Tingling indicates that there is damage or irritation of a nerve. This can be caused by bulging discs, tight muscles, etc., but these root causes will not cause tingling unless there is a nerve being affected.
All of the nerves that travel into the legs start in the low back and exit the spinal cord as nerve roots. These nerve roots then travel towards the legs, during which time they create branches and link up with other nerves, becoming what are known as peripheral nerves. These nerves then travel throughout the legs.
The main nerve roots we are concerned about that provide sensation in the legs are L2-S2. Each of these nerve roots has a specific section of the leg that is provides sensation to, although there is some variation between people. In addition, each of these nerve roots innervate specific muscles, which gives those muscles the ability to work; again, if certain muscles associated with a single (or multiple) nerve root are weaker than expected, it points toward that nerve root being the problem.
Nerve roots and peripheral nerves are connected but not the same. It can be difficult to differentiate injury to a nerve root vs. a peripheral nerve, and there is also a condition referred to as double crush syndrome, which involves injury to both the nerve root and an associated peripheral nerve. I will give an example under bullet point 3 below to better illustrate the relationship between nerve roots and peripheral nerves.
The 3 Main Causes of Tingling in the Legs
It is important to note that I am not talking about numbness in this section. Numbness is always a more severe symptom than tingling, although they commonly occur together.
1. Body’s Stress Response to the Accident
This is the most benign cause of numbness and tingling. When you are in an accident, your sympathetic nervous system is activated, which causes the release of stress hormones like epinephrine and cortisol. These hormones then circulate throughout the body and can interact with the nerves, causing them to start sending unneeded signals to the brain. Your brain then perceives these signals as tingling.
The most common location for these symptoms is in the feet and toes and can occur in either one leg or both. As your body begins to recover from the accident and becomes less stressed, the tingling will improve. Unfortunately, it is hard to tell if this tingling is just due to your stress response or actual injury to the nerves, so it is best to seek medical treatment to diagnose the cause of these symptoms.
2. Nerve Root Injury
Each of the nerve roots that exit your back correspond with specific sections of skin and specific muscles through the leg. If the nerve root is damaged or irritated, it is likely that you will have tingling over this section of your leg, as well as weakness in one or more of the associated muscles. I have attached a picture of the sections of skin related to each nerve root, which are called dermatomes.
3. Peripheral nerve Injury
Similar to the nerve roots, the peripheral nerves in the lower leg also have specific patterns that they innervate. In this area, there are a lot of nerves called cutaneous nerves, which mean they only provide sensation; there are also nerves called mixed nerves, which means they carry both sensation and stimuli for muscle contraction. Below you will see a map of the peripheral nerves in the legs.
This is a good point to provide an example of trying to diagnose whether the problem is with a peripheral nerve or a nerve root. Let’s say you have tingling over the front of your thigh. If one of your nerve roots is to blame, we would expect the tingling to be present in a band that travels diagonally across the thigh (for an example, take a look at L3 in the dermatome map above). In contrast, if the problem was in the femoral nerve – one of the peripheral nerves that provides sensation to the front of the thigh – the tingling should be present in the middle of the front of the thigh and extend from the knee to almost the groin. In both situations, we would expect to find weakness in the quadriceps, as well as a diminished patellar reflex.
Advanced Testing for Nerve Injuries
Even the most knowledgeable clinicians can struggle to determine the cause of a nerve injury. Thankfully, we have some more advanced tools to help determine what the problem is. The two most common are called a nerve conduction study (NCS) and an electromyography (EMG) study. Stay tuned for a post in the near future that explains what these are.
Summary
The three most common causes of tingling in the legs after a car accident are 1) the body’s stress response, 2) damage to a nerve root in the low back, or 3) damage to a peripheral nerve in the leg. These injuries typically have specific patterns that can help a trained provider to determine the specific cause of the tingling. However, this is not always possible, at which point, it may be time to perform nerve conduction and/or EMG studies to further diagnose the problem.
Western Slope Rehab and Performance is Here to Help
If you are struggling with injuries or have recently been in a motor vehicle accident, we can help. We are a physical therapy company that provides home-based orthopedic services in the Grand Junction, CO, area, as well as telehealth appointments throughout Colorado. If you would like to schedule a free consultation, you can call us as 970-462-9177, or fill out our contact form here.
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