What is Ulnar Neuropathy?
The ulnar nerve, one of the main nerves in your arm, can be pinched or compressed at various points, like the elbow, wrist, forearm, and upper arm. The elbow is the most common spot for this to occur. It’s crucial to stop this compression from happening and to diagnose and treat it quickly if it does, as the results can be disappointing if the nerve gets damaged.
This nerve is formed by the merging of two spinal nerves, C8 and T1, in your lower neck. It then travels down the inside of your upper arm, looping around the inner part of your elbow and then passing through the middle of your forearm muscles. At the wrist, it branches off to supply sensation to the skin on the little finger side of your hand and the half of the ring finger that’s closest to your little finger.
The ulnar nerve travels through a tunnel in your wrist formed by bones and muscles, known as Guyon’s canal. It goes on to divide into two branches. One branch continues to supply sensation to the mentioned parts of your hand, and the other branch controls some small muscles in your hand that help with fine movements.
It’s vital to protect this nerve from injury and to receive prompt treatment if damage occurs since it plays a crucial role in the functioning of the hand.
What Causes Ulnar Neuropathy?
The ulnar nerve can often get pinched or trapped in the elbow. This is the second most common nerve entrapment problem in the upper body. The ulnar nerve is more exposed in the elbow area, which makes it more vulnerable to external pressure. Regular activities that involve frequent bending and straightening of the elbow, arthritis, and deformities in the elbow can all contribute to this issue. In some people, the ulnar nerve can shift from its normal position on the inner side of the elbow upon bending the elbow.
One study found that the amount of pressure on the ulnar nerve increased to more than 200 mm Hg when the elbow was bent or when a certain forearm muscle contracted. But when the elbow was extended, the pressure dropped to less than 19 mm Hg.
Motion that puts pressure on the wrist and the muscles at the base of the little finger also increases the risk of ulnar nerve issues. This is particularly true for the ulnar nerve at the wrist. Factors like wrist fractures or growths that apply pressure on the affected area can also cause this problem.
Risk Factors and Frequency for Ulnar Neuropathy
Research on ulnar neuropathy, a type of nerve damage, is limited. One study from Italy showed that nearly 21% of people were affected, with more men than women facing the issue. Another survey in Egypt indicated that it was the second most common type of nerve entrapment.
Signs and Symptoms of Ulnar Neuropathy
Ulnar neuropathy at the elbow often begins gradually, unless it is connected to an injury. The initial symptoms include numbness and a sensation of pins and needles in the hand, especially affecting the side closest to the little finger and the little finger itself. The symptoms usually become noticeable when the elbow is bent, often at night. Although pain is not typically a primary symptom, some patients may experience it due to overuse injuries of the forearm muscles.
People might experience numbness in their little and ring fingers. Still, these symptoms could be a sign of ulnar neuropathy either at the elbow or the wrist. The fibers that connect to certain muscles in the forearm are located deep within the elbow, which makes them less likely to get injured. However, it can be difficult to differentiate between ulnar neuropathy at the elbow and at the wrist because both can present similar symptoms. If the entire ring finger is affected or remains unaffected, the diagnosis might lean more towards a nerve disorder in the neck or shoulder.
As the condition worsens, the feeling of numbness and pins and needles becomes more persistent and is accompanied by weakness in the muscles controlled by the affected nerve. The first signs of this weakness can be clumsiness and reduced dexterity in the hand, gradually leading to a decrease in grip and pinch strength. In severe cases, one may notice muscle wasting in the hand and a claw-like deformity of the ring and little fingers.
Ulnar neuropathy at the wrist and hand can present a variety of symptoms, from solely sensory to purely motor deficits. The most prevalent kind of ulnar neuropathy at the wrist results from compression of a branch of the ulnar nerve. This condition is classified into three types according to the location and nature of the nerve damage:
- Type I involves nerve damage just before or within a canal in the wrist affecting both deep and superficial branches, which causes a mix of motor and sensory deficits and results in weakness of all hand muscles receiving supply from the ulnar nerve.
- Type II primarily involves the deep branch and can lead to different patterns of weakness depending on where the nerve is compressed and is characterized by motor deficits.
- Type III affects only the superficial branch, leading to sensory deficits primarily in the palm side of the ring and little fingers. Sensory loss in Type I and Type III does not affect the back of the hand and fingers or the muscles under the little finger due to the supply from other nerve branches.
Testing for Ulnar Neuropathy
The process of diagnosing diseases traditionally depends on your medical history, a physical exam, and special tests that study the nerves and muscles. To better identify any issues with the ulnar nerve located in your arm, a combination of two tests – an electromyography (EMG) and nerve conduction velocity (NCV) – can be used. These tests help identify the exact spot where the ulnar nerve might be compressed or damaged. Early diagnosis is easier when these tests are used in patients showing signs of ulnar nerve damage.
An ultrasound is recommended as another test for patients who may have ulnar nerve damage at the elbow. It is beneficial because it can reveal the shape changes and the degree of damage suffered by the ulnar nerve at the elbow. A recent research review indicated that in healthy participants, the ulnar nerve’s size at different points around the elbow is typically no more than 10 mm. Any measurement above this could indicate ulnar nerve entrapment, a condition where the nerve is compressed at the elbow region.
Another study suggested that by measuring the ulnar nerve’s size with an MRI or ultrasound scan 1 cm above the inner side of the elbow bone, we could identify patients with or without ulnar nerve entrapment using a size of 11.0 mm as a dividing point.
Other suggestions include the ratio of the swollen ulnar nerve, the presence of blood vessels inside the nerve, an increased squishing ratio, and an enlarged area within the nerve that is darker on ultrasound (intra-neural hypoechoic fraction). However, more research must be done to confirm these indicators.
Treatment Options for Ulnar Neuropathy
There are two main non-surgical treatments for ulnar nerve pressure at the elbow. These aim to reduce any stress on the ulnar nerve by limiting the elbow joint’s frequent bending and pressure. This can be achieved through the use of elbow splints, elbow pads or sleeves, and physical therapy. These treatments are generally suitable for people with mild to moderate symptoms.
Studies have shown that non-surgical methods can be very beneficial for about 90% of the people with mild symptoms. However, for people with moderate symptoms, these methods seem to have a lower success rate, with only 38% finding relief through them.
Another treatment option suggested involves injection procedures at the elbow. However, there are conflicting results with this method, especially when performed with ultrasound-guided corticosteroid injections.
If the symptoms persist, if there are changes in sensation, or if muscle wasting is observed, surgical treatment may be considered. Numerous surgical methods have been suggested, including decompression (relieving pressure), anterior transposition techniques (moving the nerve to a different position), and medial epicondylectomy (removing part of the bone). However, according to a detailed review of many studies, simple decompression and decompression with transposition were found to be equally effective for people with ulnar nerve entrapment or pressure where there is no apparent cause. It was noted, though, that the decompression surgery that involved moving the nerve was linked with more infections in the wound than simple decompression.
What else can Ulnar Neuropathy be?
The following are some health conditions that can cause symptoms similar to carpal tunnel syndrome:
- Alcohol-related neuropathy (nerve damage due to excessive alcohol use)
- Amyotrophic lateral sclerosis (ALS, a degenerative nerve disease)
- Brachial plexus abnormalities (issues with the nerve network sending signals from your spine to your shoulder, arm, and hand)
- Cervical disc disease (damage to the discs in your neck)
- Epicondylitis (an inflammation of areas where tendons in the elbow are attached to bone)
- Pancoast tumour (lung cancer)
- Thoracic outlet syndrome (group of disorders that occur when blood vessels or nerves in the space between your collarbone and your first rib are compressed)
- Traumatic peripheral nerve lesions (nerve damage in the limbs due to injury)
