What is Radial Nerve Injury?
The radial nerve is a nerve that starts from the back part of a network of nerves in your shoulder, called the brachial plexus, and supplies the upper arm. It’s also responsible for controlling the muscle that extends the arm – the triceps brachii – and the muscles at the back of your forearm, which help to extend your wrist and fingers. In addition, it provides sensation to the back area of your forearm and hand.
The radial nerve connects to various muscles including the triceps, anconeus, and several others that help with the movement of your wrist and fingers. This nerve also branches out into a deeper one, which helps move other muscles like the extensor digitorum, supinator muscle and several others that control the movement and dexterity of your fingers and thumb.
The radial nerve also provides sensation to certain parts of your arm and forearm, as well as the back of your hand and fingers.
To check the health and functionality of the radial nerve, doctors perform certain tests. For instance, they may ask you to extend your thumb against resistance to assess motor function, and to differentiate between two points on the back of your thumb to assess sensory function.
Despite these quick tests, a detailed physical exam is always essential to diagnose any potential problems. Injuries to the radial nerve can produce various signs and symptoms, depending on where and how the nerve has been injured.
What Causes Radial Nerve Injury?
The radial nerve can get damaged in various ways, often after a traumatic event. The radial nerve is one we use quite a lot – it controls movement in the upper arm, forearm, hand, and fingers. So injuries to the radial nerve can happen in various ways like:
- Breaking the upper arm bone, especially in a spiral pattern near the bottom of this bone. This is known as a Holstein-Lewis fracture and is associated with 15 to 25% chance of causing some damage to the radial nerve.
- Using crutches incorrectly.
- Overusing the arm from too much physical work or playing a lot of sports.
- Work-related accidents.
How a radial nerve injury shows up depends on the location and type of injury on the nerve. For example, if the nerve gets injured near the armpit, it would present differently than if it were injured near the bottom of the arm.
Risk Factors and Frequency for Radial Nerve Injury
Radial mononeuropathies, or specific types of nerve damage, are common but determining the exact number of radial nerve injuries that cause them is tricky. Currently, there isn’t a lot of data or widespread studies available. One older study from the late 80s did suggest that the radial nerve, located in your upper body, is the most frequently injured, but this point is up for debate.
Signs and Symptoms of Radial Nerve Injury
Radial neuropathy is a condition that affects the nerves in your arm. People with this issue often feel like they have to support the affected arm with their healthy one. They may also notice they have less feeling or no feeling at all on the top, thumb-side of their hand and wrist. They can’t extend their wrist, thumb, and fingers as they usually could. They might not notice the problem when their hand is palm-up because gravity helps with movement. But when they turn their hand palm-down, their wrist and hand may suddenly droop, causing what is known as “wrist drop”.
If the nerve is damaged at the armpit, a person can lose the ability to extend their forearm, hand, and fingers. The result is typically a “wrist drop” seen during a physical examination. Sensations might be lost in the side of the arm and the backside of the forearm, spreading to the thumb-side top part of the hand and fingers. These symptoms are common in “Saturday night palsy” and the incorrect use of crutches (known as “crutch palsy”). Whenever harmful forces are used or there is too much pressure in the armpit, it could potentially affect the radial nerve, which is connected to the network of nerves in our arms called the brachial plexus.
Damage to the radial nerve below the elbow joint can occur due to:
- Elbow dislocations
- Elbow fractures
- Wearing a cast or wrap that is too tight
- Rheumatoid or inflammatory arthritis diseases
These conditions cause a weakness in extending the hand and fingers, leading to finger drop and a partial wrist drop.
The posterior interosseous nerve syndrome can also occur if the radial nerve below the elbow is damaged. This nerve branch controls muscle movement of the extensor compartment. When it is affected, it causes pain in the forearm and wrist, as well as weakness when extending the fingers and wrist.
Lastly, it is possible to damage the nerve at the end of the forearm due to Wartenberg syndrome, an entrapment of the nerve between two muscles, often caused by wearing tight jewelry or watches. You might feel numbness and tingling in the thumb-half side of the top of the hand and the same half of the fingers, but motor function remains intact.
Testing for Radial Nerve Injury
If you have a traumatic injury, likely, x-ray images are a good enough test for your doctor to see what’s going on. This is particularly true for injuries like broken bones. If there’s a need to rule out or investigate nerve-related problems, such as compressed nerves, more advanced imaging tests, such as magnetic resonance imaging (MRI), can give more detailed visual information.
Tests like electromyograms or nerve conduction studies (EMG/NCS) can also be helpful. These tests measure how fast nerve impulses travel and can help doctors figure out whether the problem is with a nerve or a muscle. EMG/NCS is also used to monitor changes and observe nerve recovery over time. On a positive note, more than 90% of radial nerve palsies recover naturally over 3 to 4 months, typically only requiring observation during this time.
There’s also another test that could be used if available called an ultrasound. This was recently found to help diagnose radial entrapment neuropathy at spiral groove quickly. It’s another tool for evaluating nerve-related issues.
If you’ve been diagnosed with radial nerve palsy, the return of function follows a particular pattern. Certain muscles like the brachioradialis and ECRL are the first to recover, while others like the EPL and EIP are usually the last.
Treatment Options for Radial Nerve Injury
Treatment options range based on how severe the injury is and what symptoms you’re experiencing. These methods may include:
* Pain relief medications, which can be taken orally or applied to the skin. These are called non-steroidal anti-inflammatory drugs (NSAIDs)
* Corticosteroid injections are a type of medicine that is used to reduce inflammation (swelling)
* Physical therapy, which uses exercises and other methods to help improve movement and strength
* Wearing a splint on the injured area for at least 2 to 4 weeks, or until you no longer feel any symptoms.
Treatment usually helps patients to recover within about 4 months, provided the nerve isn’t torn or sharply cut. For short-term injuries where the radial nerve (the nerve that runs along the arm) is squeezed, the outlook is generally promising.
Some radial nerve injuries may need a more serious form of treatment. If the radial nerve is trapped or squeezed and symptoms persist for several months, you may require surgery to relieve the pressure on the nerve. Surgery is always considered as a last resort.
What else can Radial Nerve Injury be?
At times, it can be challenging to tell the difference between nerve damage in the arm (known as radial neuropathies) and damage to the central nervous system. Both can lead to a condition called wrist drop, which results in weakness when trying to extend the wrist. To differentiate between these two conditions, there is a simple test doctors can use; they examine a muscle in your forearm called the brachioradialis muscle. If this muscle is weak, it’s likely an issue with the radial nerve in your arm. However, if this muscle is less affected, it could point to a problem in your central nervous system.
What to expect with Radial Nerve Injury
Most injuries or fractures to the upper arm bone, also known as the humerus, can get better on their own. In fact, statistics show that up to 92% of these cases improve just with monitoring over the course of about 3 to 4 months.
Possible Complications When Diagnosed with Radial Nerve Injury
Injuries to the radial nerve are typically managed with non-invasive methods like physical therapy and the use of a splint. However, if surgery becomes necessary, there may be a risk of complications after the procedure. Here are some potential complications:
- Stretching of the nerve
- Nerve getting cut
- Incomplete release
- Decrease in muscle mass due to disuse
Preventing Radial Nerve Injury
For the most effective health outcomes, patients need to stay consistent with their personalized treatment plans. Regular check-ups with their doctors are also crucial for monitoring progress. Equally important is the role of the doctors to explain the available treatment options, discuss the likely course of recovery, and potential complications to the patient. This helps the patients to understand their treatment better, enhancing their compliance and overall well-being.