Overview of Electrodiagnostic Evaluation of Lumbosacral Radiculopathy
Lumbosacral radiculopathy is a medical term that refers to a disorder affecting the nerves in the lower back and hip area of your spine. This condition is typically caused by nerves being squeezed by structural changes in your spine, such as a herniated disc, stiffened joint, or bone spur. However, it can also be caused by irritation from an infection, tumor, or inflammation in the tissues surrounding the nerves.
If you have this condition, you might feel several symptoms, like numbness or prickling sensations, weakness, and shooting pain, like an electric shock. These symptoms usually affect just one side of your body. During a physical check-up, your doctor might find that certain muscles are weaker, your sensitivity to touch has diminished in certain areas of skin, or reflex tests do not work as expected. All of these findings help them pinpoint what specific nerve root is affected.
Since patient symptoms can vary greatly, your doctor might require an electrodiagnostic evaluation for an accurate diagnosis. This type of test helps doctors understand the location, type and severity of the disruption on the nerves. This includes a nerve conduction study, which tests how well electrical signals move along a nerve, and a needle electromyography study, which measures the electrical activity among muscles and nerves. Both of these steps provide comprehensive insights and assists in providing a more focused diagnosis.
Anatomy and Physiology of Electrodiagnostic Evaluation of Lumbosacral Radiculopathy
In the lower part of your spine, known as the lumbosacral region, there are eleven pairs of spinal nerves. These nerves come out from your spinal cord and are responsible for carrying signals for feelings (sensory) and movement (motor) to different body parts. Some nerves in the lower part of your spine split into two parts: one part carries sensory information and the other part carries motor information.
This complex network of nerves divides and merges again as it travels down your body. The roots of these nerves meet to form a mixed nerve which carries both feeling and movement information. This combined nerve then splits again to form two separate nerves. One is responsible for muscle support around the spine and the other is involved in your body movements.
These nerve processes help doctors understand certain medical conditions. For instance, in a condition known as lumbosacral radiculopathy which affects the nerves in your lower back, certain findings in medical tests can help doctors determine the root cause of the condition. If an issue is found within the spinal cord, it often affects the movement related nerve more than the sensory nerve.
Different types of lumbosacral radiculopathy are associated with different symptoms. For example, for the L2 radiculopathy, a patient may experience a loss of sensation in the front and side parts of the thigh. For the L3 radiculopathy, the patient may have weakness in the hip and thigh, and sensory loss on the inner part of the thigh. Some conditions can have similar symptoms with these radiculopathies, such as femoral neuropathy.
The most common condition involving these lower spine nerves is the herniation of the L4 disc. The patient may experience numbness and a tingling feeling in the inner part of their lower leg, and may have weaker knee-jerk reflexes.
L5 radiculopathy affects a nerve in the lower back and can lead to diminished sensation in the front and side of your lower leg, as well as the top of your foot, which can in-turn result in foot drop and difficulty walking.
S1 radiculopathy affects another nerve in the lower back, and can manifest as difficulty in walking on toes, weakness in bending the foot downward, or diminished Achilles reflex. Some conditions can present symptoms similar to S1 radiculopathy, like sciatic neuropathy, but certain specific tests like an H-reflex test can help identify S1 radiculopathy.
Why do People Need Electrodiagnostic Evaluation of Lumbosacral Radiculopathy
If a patient is experiencing things like numbness, pain, or a pins-and-needles feeling (known as paresthesia) in a particular area of the skin, or weakness in certain groups of muscles, or they have reduced or missing natural reflex reactions, and there isn’t a clear cause identified by imaging tests like X-rays or MRIs, they may be recommended to take a special type of test known as electrodiagnostic testing. This test is used to reveal any issues related to the nerve roots, which are the points where nerves branch out from the spine to the rest of the body. Therefore, these symptoms corresponding to a specific nerve root might need further investigation through electrodiagnostic testing.
When a Person Should Avoid Electrodiagnostic Evaluation of Lumbosacral Radiculopathy
Nerve conduction studies and needle electromyography are tests used to study the electrical activity of muscles and nerves. Even though these tests have been proven to be safe, there are certain precautions that need to be taken before conducting them. It is very important for doctors to know about all the medications their patients are taking. For example, if a patient is taking a medication known as an anticoagulant, which prevents blood from clotting, it might not be safe to perform needle electromyography.
Needle electromyography should also not be performed on patients with uncontrolled bleeding disorders. Additionally, this test should be avoided if a patient has an active skin infection like cellulitis, or if they have a condition called lymphedema (which causes swelling in the limbs) as it increases the risk of developing another infection.
In the case of nerve conduction studies, these should not be conducted in patients who have a device called a cardiac defibrillator implanted in their bodies. And for those with a cardiac pacemaker, while it’s generally safe to do nerve conduction studies, the electrical stimulation used in the test should not be applied directly over where the pacemaker is implanted.
Finally, it is always recommended to fully discuss the potential risks of these tests with each patient and also involve their primary doctor. This ensures the tests are carried out in the safest manner possible.
What Else Should I Know About Electrodiagnostic Evaluation of Lumbosacral Radiculopathy?
Nerve conduction studies are tests that measure how quickly your nerves send signals. These tests can help identify nerve damage. They can be particularly useful in diagnosing disorders such as lumbosacral radiculopathy, a condition that causes back pain and weakness in the legs. To understand these tests, here’s a breakdown of some of the key terms and components:
– Sensory: Sensory nerve action potentials (SNAPs) are signals that travel along sensory nerves. In a condition like radiculopathy, these signals are usually normal because the problem is closer to the spine than to the nerve ending itself – meaning the nerve and the cell it’s attached to are still intact. If the SNAP isn’t normal, it might be because of a different condition.
– Motor: Motor nerves control your muscles, and often, the muscles in your arms and legs are controlled by more than one motor nerve. So, if you have radiculopathy, a test that measures the signals traveling to your muscles (a compound muscle action potential or CMAP) might still look normal.
The significant point here is that nerve conduction studies can help rule out other conditions that might look like radiculopathy. It helps confirm a diagnosis of radiculopathy, especially if the tests are used in combination with the needle electromyography, which is a more detailed study about individual muscle activity.
Needle electromyography involves placing small needles in your muscles to record their electrical activity. The presence of abnormal wave patterns or spasms in the muscles can support a diagnosis of lumbosacral radiculopathy. This test involves checking at least three different muscles- one back muscle and two limb muscles associated with the same nerve root but controlled by different peripheral nerves.
It’s also essential to differentiate between radiculopathy and a similar condition called lumbar plexopathy. The electromyography of the back muscles normally remains unaffected in lumbar plexopathy; thus, evaluating the back muscles can help differentiate between these two conditions.
