Overview of Electrodiagnostic Evaluation of Cervical Radiculopathy
Cervical radiculopathy is a condition caused mostly when a nerve root gets compressed. Diagnosing this condition involves understanding the patient’s symptoms, conducting physical examinations of sensory and motor responses, and if needed, electrodiagnostic tests. Electrodiagnostic tests are often used for confirmation and to determine the future outlook of the health condition. Though these tests might not always be necessary if the condition is clearly evident through symptoms alone.
The most common reason for nerve compression, leading to radiculopathy, is disc herniation. Disc herniation is when one of the rubbery discs that cushion the bones in the spine slips out of place. However, other factors can also cause nerve compression. These include bone spurs (osteophytes), an overgrowth of the joints in the spine (facet hypertrophy), and thickening of the ligaments in the spine (ligamentous hypertrophy).
There are also non-compressive causes of radiculopathy. These include trauma, tumors, infections, the loss of insulating covers of nerve cells (demyelination), stroke (infarction), and damage from radiation therapy. However, these can’t be told apart from compressive causes through electrodiagnostic testing unless they affect multiple muscle groups and sensory zones (also known as multiple myotomes and dermatomes).
Anatomy and Physiology of Electrodiagnostic Evaluation of Cervical Radiculopathy
People with a condition called cervical radiculopathy often have neck pain that spreads to their arm. This pain can be accompanied by a numb or tingling feeling, which is due to a pinched nerve. Additionally, if a nerve responsible for muscle movement is affected, patients may experience weakness in the corresponding area.
During a check-up, doctors need to examine the patient’s muscle strength, sensation, and reflexes on both sides of the body. They also look for any signs of muscle shrinking. Symptoms can vary among patients, but common ones include decreased reflexes, weakness in muscles connected to the affected nerve, and sensory problems in a certain pattern. A significant sign is a reduced triceps reflex, particularly due to a nerve involvement in an area called C7. However, not all these signs can be caught during a physical exam because patients may experience them differently. To help with this, a technique called electromyography (EMG) can be used to detect even small loss of motor nerve fibers, which might not be found during a physical check-up.
To properly examine someone for cervical radiculopathy, it’s important to understand the anatomy of this area. Spinal nerves, which comprise of sensory and motor nerves mixed together, form various parts of the nerves around the spinal area. After the nerve leaves the gap between the vertebrae (bones), it divides into two parts – one goes towards the front and forms the cervical and brachial plexuses (networks of nerves), and the other one goes towards the back to supply the muscles and skin of the neck and back. Each nerve related to the cervical area departs from a hole on top of each corresponding bone till an area called the C8 nerve root.
Why do People Need Electrodiagnostic Evaluation of Cervical Radiculopathy
Cervical radiculopathy is a condition that can be recognized by understanding a patient’s medical history and carrying out a thorough physical examination. In some cases, we use an electrodiagnostic evaluation. This is a method used to confirm the condition and differentiate it from other disorders which have similar symptoms. It’s especially helpful when patients display unusual symptoms, have weakness triggered by pain, or when the imaging tests don’t show a specific problematic area.[4]
Before getting any diagnostic exams, doctors must know your past medical history, your current symptoms, and perform a complete physical examination.
During the physical exam, doctors look for muscle shrinkage, check the strength and sensation of upper limbs, and the reflexes of both sides of the body. Additional tests like the Spurling test might be done. During this test, your neck is stretched and bent sideways to put pressure on the nerve that’s exiting the spinal cord. This test helps in diagnosis if it triggers the radiating sensations related to nerve damage.[4] The Spurling test is precise in its identification, but its sensitivity isn’t so high for cervical radiculopathy. However, when it is combined with other tests like axial traction, a positive result can significantly suggest the presence of cervical radiculopathy.[4][6]
Tests such as the Hoffman sign and Babinski response can indicate an upper motor neuron disorder. Electrodiagnostic studies in cervical radiculopathy can only assess the C4-C8 and T1 nerve roots, as these are the only ones represented in the upper limbs. It’s common to see radiculopathy, a condition where a nerve root in the spine is compressed, affecting the C7 nerve root, followed by the C6 nerve root.
When a Person Should Avoid Electrodiagnostic Evaluation of Cervical Radiculopathy
There are certain situations where conducting electrodiagnostic studies, which are tests to measure the electrical activity of your muscles and nerves, may not be safe for patients with cervical radiculopathy, a condition where nerve roots in the neck are compressed or irritated. Here are a few of them:
Firstly, a test called Needle Electromyography (EMG), which involves inserting fine needles into muscles to record their electrical activities, cannot be done on patients who have severe bleeding disorders. This would make it difficult for the patient’s blood to clot and stop any bleeding that might occur during the test.
Additionally, these needles should never be used on areas of the body with active soft tissue infections, as it could potentially spread the infection.
Another kind of electrodiagnostic study, Nerve Conduction Studies (NCS), which also test the electrical activity of your nerves, is not recommended for patients who have implanted cardiac defibrillators or are connected to external defibrillators. These are devices that can monitor and correct irregular heartbeats. The electrical stimulation from the NCS could interfere with these devices, so the test should not be performed directly on or near them.
Equipment used for Electrodiagnostic Evaluation of Cervical Radiculopathy
When doctors perform electrical tests to diagnose neck-related nerve problems (known as cervical radiculopathy), they use the following equipment:
- An EMG/NCS machine: This is a special machine that measures the electrical activity of your muscles and nerves.
- Needle electrodes: These are tiny needles that the doctor inserts into your muscles to record their electrical activity.
- Surface electrodes: These are sticky patches that the doctor puts on your skin. They can pick up the electrical signals from your nerves and muscles. There are three types – active, reference, and ground.
- Amplifiers: These devices amplify (or increase) the small electrical signals from your nerves and muscles, allowing them to be more easily measured.
- Filters: These help to clear up the signal by removing unwanted noise or interference.
These tools help your doctor to better understand how your nerves and muscles are working, which can provide important information in diagnosing your condition.
How is Electrodiagnostic Evaluation of Cervical Radiculopathy performed
If you’re getting tested for cervical radiculopathy, which is a condition that causes neck pain and numbness because of pressure on the spinal nerve roots, the physiatrist (a doctor specializing in physical medicine and rehabilitation) or technician will first explain the procedure to you. They will talk about why the test is necessary, what will be done during the test, and what complications might occur.
The physician will then use Electrodiagnostic tests such as needle electromyography (EMG) and nerve conduction studies (NCS) which are used to evaluate the health of your muscles and the nerves controlling them. These tests will be performed on both sides of your body, so the results can be compared. It’s important to note that these tests should be performed in a room where the temperature is at or above 32 degrees Celsius (or about 90 degrees Fahrenheit). If the room is too cold, it can cause inaccurate results.
A piece of advice is to reduce any electrical interference from other devices around you during the test. These can interfere with the electrical signals in your body and affect the accuracy of the test.
Three electrodes (small devices that conduct electricity) will be used during the test. The “active” electrode is placed on the relevant muscle, the “reference” electrode is placed on a nearby tendon or bone, and the “ground” electrode is placed somewhere between the stimulant and recorded electrode to minimize any disturbances during recording.
When a needle exam is being performed, a needle is quickly inserted into the muscle. You might feel a small amount of discomfort. The needles are used to send electrical signals into your muscle, and these signals are then recorded. The physician will look at these recordings to get information about your muscle and nerve health.
When testing for cervical radiculopathy, six muscle groups are tested, including one in the neck called the paraspinal muscle. The doctor will be looking at several things in these readings, such as the size of the electrical signal (amplitude) and how quickly the signal begins (onset latency). Remember, this test is designed to help diagnose your condition correctly and guide the best treatment for you.
Possible Complications of Electrodiagnostic Evaluation of Cervical Radiculopathy
Procedures that involve using electricity to diagnose medical conditions usually have low risks. But like all medical procedures, there could be a few complications:
* There’s a slight chance of getting an infection because of the needle used during the test.
* A small amount of bleeding might occur at the place where the needle was inserted.
* The test could cause discomfort. If this discomfort is too severe, then the test may need to be stopped.
What Else Should I Know About Electrodiagnostic Evaluation of Cervical Radiculopathy?
Patients with cervical radiculopathy, a condition where one or more nerves in the neck are compressed, often feel pain, numbness, or tingling in their arms. To diagnose this condition, doctors often use different types of nerve tests.
In most cases of cervical radiculopathy, the nerve tests will be normal. This is because the problem occurs at the nerve root, which is the area where the nerve is compressed. If the tests show anything unusual, it may be a sign of another condition, like carpal tunnel syndrome or an ulnar nerve entrapment, which put pressure on a nerve in your wrist or elbow, respectively.
When checking your nerves, doctors usually examine the following areas: Median Thumb C6, Median Index C6-C7, Radial Thumb C6-C7, and Ulnar Little Finger C8.
If the nerve compression is severe enough that it’s stopping nerve fibers from connecting to their cells, a condition called Wallerian degeneration can occur. This is where the part of the nerve cell that’s far away from the cell body begins to break down. If this happens to more than half the motor axons (nerve fibers that transmit signals to muscle cells), the signal strength compared to the other limb may decrease.
Removing or testing a small amount of muscle tissue, often through a needle, can also help in diagnosing cervical radiculopathy. This process is known as electromyography. This is helpful for determining potential future outcomes for the patient. However, it may not detect early cases of radiculopathy.
When severe radiculopathy happens, it can cause a condition known as Wallerian degeneration. Electromyography can detect this by showing signals from muscle fibers that are firing on their own. These appear and sound a specific way.
Sometimes, these signals can appear in people without cervical radiculopathy. Also, after spinal surgery, this doesn’t always signify a problem as these can remain abnormal for years.
Finally, it’s crucial to test specific muscles to diagnose cervical radiculopathy accurately. The doctor will decide what muscles to test based on a physical exam and the patient’s symptoms. The testing will help the doctor figure out if the problem is with the nerve roots, plexus, which is a network of intersecting nerves, or peripheral nerve entrapment, which is the compression of a nerve at other locations, and not at the root. To confirm the diagnosis, both nerve pathway tests and muscle tests must show positive results. Still, keep in mind that a negative result doesn’t rule out the condition.
In such tests, doctors often focus on specific muscles, including the Brachioradialis C5, Deltoid C5-6, Biceps C5-6, Flexor Carpi Radialis C6, Triceps C6-7, First Dorsal Interosseous C8-T1, Flexor Pollicis Longus C8, and Abductor Digiti Minimi C8-T1.
Each of these muscles reflects different nerves, meaning different potential sites for the compression responsible for the patient’s symptoms. This helps the doctor identify precisely which nerves are affected so they can come up with the best treatment plan.
