Overview of Electrodiagnostic Evaluation of Brachial Plexopathies
Brachial Plexus injuries, also known as brachial plexopathies, are serious nerve injuries that can greatly affect a person’s quality of life. They can be caused by a number of different incidents, such as falls, sports injuries, and childbirth. Other causes include prolonged pressure on the nerves from using crutches or carrying heavy backpacks, accidents involving cuts or punctures, blood flow issues, and growth of abnormal cells or tumors.
Most people with this type of injury experience a combination of weakness and numbness or tingling in the arm, hand, or shoulder. These symptoms usually match the area served by the damaged nerves. Doctors start their assessment of this kind of injury through a detailed evaluation of the patient’s medical history and a thorough physical examination. This helps identify the exact location and extent of the damage.
Once the doctor has an idea of what might be causing the symptoms, they use tests like X-rays or scans to get a better look at the area. In addition, they may also use electromyography and nerve conduction studies, which are specialized tests that use small electric shocks to measure the activity and health of nerves and muscles. These tests are critical to diagnose the brachial plexopathy accurately and understand how severe the injury is. This article particularly focuses on how these last two tests can be used to identify and understand the progress of brachial plexopathies.
Anatomy and Physiology of Electrodiagnostic Evaluation of Brachial Plexopathies
The brachial plexus is a network of nerves, which originate from certain areas of the spinal cord and are responsible for sending signals from your spinal cord to your arm, shoulder, and hand. Imagining the brachial plexus is like looking at a tree: it starts with the “roots” from the spine, moving to “trunks”, then into “divisions”, then “cords”, and finally branching out into five key nerves: the axillary, musculocutaneous, median, radial, and ulnar nerves. Each of these nerves plays a crucial role in the sensation and movement of different parts of the upper body.
The brachial plexus can be damaged in various ways. Common injuries include being pulled or torn away, or getting pinched or compressed. The area most at risk is the part which is close to the collarbone, as it is exposed and can get injured with extreme movements of the neck or upper arms. Problems here can cause a condition called Erb’s palsy, leading to stiffness and lack of movement in the arm. Another condition called Klumpke’s palsy, which can cause a “claw hand deformity”, affects the nerves lower down the plexus. This is less common and often results from the arm being forcefully raised above the head.
Nerve damage to the brachial plexus can be caused by several factors. For example, using crutches improperly can damage the plexus beneath the collarbone, whereas carrying a heavy backpack can compress the area around the neck and shoulders. Penetrating injuries, like stab wounds, can also harm the nerves.
Understanding how these injuries happen and which nerves are affected can help doctors pinpoint the source of the problem. Here’s a quick summary for each key nerve:
The axillary nerve, coming from your spine and the back of the brachial plexus, controls the deltoid and teres minor muscles in your shoulders. If it’s damaged, you might experience difficulty in moving your arm, particularly in lifting it sideways, and a lack of sensation on the upper side of your arm.
The musculocutaneous nerve, coming from upper portions in the spinal cord and the side of the brachial plexus, affects the coracobrachialis, biceps brachii, and brachialis muscles. Damage to this nerve could lead to the arm not being able to bend at the elbow and a loss of feeling on the outer part of your forearm.
The median nerve, coming from various points along the brachial plexus, controls most of the muscles that bend your forearm as well as several muscles in your hand. Damage to this nerve can cause difficulty in bending your wrist and fingers, numbness in the palm and fingers, and will affect your grip (sometimes called an “ape hand” deformity).
The ulnar nerve, coming from the lower part of the spinal cord, affects muscles that bend your wrist and fingers. If damaged, it could cause numbness in your fingers, and weakness when attempting to grip (causing a “claw hand” deformity).
The radial nerve, coming from different parts of the plexus, controls muscles of your forearm that help in straightening out your arm and wrist. An injured radial nerve could lead to difficulty in straightening your arm and hand and lack of sensation on the back of your forearm and hand.
Doctors diagnose these issues by studying your symptoms and selecting tests accordingly. By tracing back the affected areas, they can identify the exact location of the damage.
Why do People Need Electrodiagnostic Evaluation of Brachial Plexopathies
Electrodiagnostic studies are medical tests used to diagnose and provide information about neurological injuries or diseases. These studies can help determine the location, potential future outcomes, timeframe, and severity of these medical conditions. They are also useful in distinguishing between different types of nerve damage, such as axonal (related to the long part of a nerve cell) or demyelinating lesions (damage to the protective layer around a nerve).
Furthermore, these studies can help identify if the issues are related to motor nerves (which control muscle movement), sensory nerves (which help you feel things), or autonomic nerves (that control internal body processes like heart rate and digestion). They can also demonstrate if the lesions or injuries are widespread, focused in one area, or present in multiple areas.
Electrodiagnostic studies can also be used to tell the difference between muscle diseases and disorders at the junction where the nerve communicates with the muscle, as well as injuries that are the result of trauma.
However, it’s important to note that some types of nerve damage might not show up in these studies. Damage that only affects A-delta and C fibers, which are specific types of nerve fibers, will typically produce normal results in these tests.
When a Person Should Avoid Electrodiagnostic Evaluation of Brachial Plexopathies
Electrodiagnostic studies, which are tests that help doctors understand and diagnose conditions related to the muscles and nerves, usually have no restrictions. These tests are even considered safe for pregnant women. However, not everyone tolerates these studies well. For example, some people are more sensitive to electricity and may find the procedure uncomfortable.
There are some instances when doctors might have to think twice before conducting an electrodiagnostic study. These instances include:
If a person has an infection where the needle for the EMG (a type of electrodiagnostic test) is to be inserted, it is usually best to avoid that area.
For people who have devices like a pacemaker wires or central lines (tubes inserted into large veins for long-term treatment), these tests should be conducted with caution. The electrical impulses during the tests could potentially interfere with these devices and cause irregular heartbeat.
If a person has swollen areas on their body (edema or lymphedema), doctors may avoid doing tests in those areas, as there may be a higher risk of infection.
The most common problem people usually face after an EMG is pain where the needle is inserted. Some people find this pain too much to bear.
People who are regularly taking blood thinners or those who have bleeding disorders may bleed excessively. For these people, the needle should only be inserted into the muscles near the skin’s surface.
Equipment used for Electrodiagnostic Evaluation of Brachial Plexopathies
You can find equipment used for EMG (Electromyography) and NCS (Nerve Conduction Study) tests in the market. These machines typically include several parts:
The first is a computer, which processes and graphs electrical signals. This is the brains of the operation, turning raw data into something we can understand.
Next, we have speakers, which give out sounds based on the electrical activity levels. This helps doctors understand what’s happening in real-time.
Then, there is a printer, which provides a visual representation of the electric impulses, essentially showing what’s happening under your skin.
One of the key components is an amplifier; it makes the tiny electrical activity in your body strong enough to be recorded and analysed. This is essential as our natural electrical signals are very faint.
Another important part is the stimulator, which creates an electric shock used for the tests. Don’t worry, it’s not harmful and doesn’t hurt!
Then, surface electrodes get attached to your skin. They stimulate and record the electrical pulses for the Nerve Conduction Study.
Lastly, there are disposable needle electrodes. These are used for recording electrical rush during the EMG test. You might feel a little prick, but they’re generally not painful.
How is Electrodiagnostic Evaluation of Brachial Plexopathies performed
When a doctor wants to check how well your nerves and muscles are working, they might use an electrodiagnostic evaluation. This usually involves three parts: nerve conduction studies, electromyography, and somatosensory evoked potentials.
For nerve conduction studies, they’ll place two tiny sensors on your skin. One sends out a small electric pulse and the other records how that pulse moves along your nerve. This gives the doctor a way to see how well your nerves can send and receive signals. They can do this for both your motor nerves, which control muscles, and sensory nerves, which help you sense things like touch and temperature. The doctor will look at both the size of the response (like how loud it is) and how long it takes your nerves to respond.
Next up is electromyography or “EMG”. For this, the doctor uses a small needle to record the electrical activity inside your muscle. This is a more subjective test, meaning its interpretation depends more on the doctor’s judgement. They’ll check the activity when the muscle is resting, then have you tighten the muscle to different levels and measure what happens. If your muscles give off certain electrical patterns, it can suggest different problems with your nerves or muscles.
The third part of the evaluation is a little more complicated. With somatosensory evoked potential measurement, the doctor can test the whole nerve pathway from your skin all the way up to the brain. This can help them figure out whether the problem is with your peripheral nerves (the ones in your arms and legs) or with your central nervous system (your brain and spinal cord).
They’ll stimulate a nerve in your arm or leg, then check the electrical response in different parts of your nervous system. This can help find exactly where the problem is.
When the doctor does these tests they are looking for certain signs of damage to your nerves or muscles. These include lower than normal responses, slow responses, or problems with the speed at which your nerves carry signals. They start by checking your nerves one by one and comparing the results with what’s normal.
If these tests show something unusual, this can give the doctor clues about what’s causing your symptoms. This can help them determine the best treatment for you. Even if the tests don’t find a problem, they can still be helpful by ruling out certain conditions.
Possible Complications of Electrodiagnostic Evaluation of Brachial Plexopathies
After a medical examination involving needles, the most common side effect is slight discomfort, tenderness, or bruising where the needle was inserted. In rare instances, this site might get infected. Instances of serious bleeding and formation of a blood clot under the skin, known as a hematoma, are exceedingly rare. However, patients who take blood thinners should get tests to check their blood’s ability to clot.
If you’re pregnant, there seems to be no risk of complications from these types of tests. And, to the best of our knowledge, there have been no reported cases of nerve injury caused directly by these types of tests.
One of the more severe but extremely rare complications when testing the muscles of the trunk (that’s the part of the body excluding limbs and the head) is a collapsed lung, or pneumothorax.
For those with deep brain stimulators or vagal nerve stimulators, these devices can interfere with the test results as they also produce electrical activity. In such cases, it’s necessary to communicate and plan with your treating doctors to temporarily turn these devices off during the medical test.
What Else Should I Know About Electrodiagnostic Evaluation of Brachial Plexopathies?
Electrodiagnostic studies, which include tests like nerve conduction studies and electromyography (EMG), are an important tool for doctors in understanding and treating neurological conditions. These conditions can sometimes be hard to diagnose, because their signs and symptoms can be vague or similar to other diseases.
These studies help doctors in several ways. Firstly, they confirm the presence of a neurological issue. Secondly, they help to pinpoint where in the body this issue is happening. Thirdly, they provide helpful information about the progress of the disease, including how old it is and how severe it has become.
For example, if a patient is suspected to have an issue with their brachial plexus (the network of nerves that send signals from your spine to your shoulder, arm, and hand), these tests can help the doctor confirm this and find the exact location of the problem.
These studies can also be done more than once over a period of time, which allows the doctor to see how the patient’s condition is changing and whether they are recovering after an injury. Additionally, these studies can be used together with imaging tests (like X-rays or MRIs) to provide more information. This all helps the doctor in making decisions about treatment – for example, in deciding whether a patient needs a surgical procedure or not.
In short, electrodiagnostic studies are a valuable tool in a doctor’s toolkit for diagnosing and managing neurological conditions.
