Ulnar Nerve Entrapment

What Is It, Symptoms, Causes, Treatment, and More

Author: Lahav Constantini

Editors: Antonella Melani, MD, Lisa Miklush, PhD, RN, CNS

Illustrator: Jillian Dunbar


What is ulnar nerve entrapment?

Ulnar nerve entrapment is a compressive neuropathy that occurs when the ulnar nerve is trapped or compressed, and can lead to progressive damage. The ulnar nerve is one of the three main branches of the brachial plexus, which is a network of nerves originating from the spinal cord in the neck and travelling down the arm. After leaving the spinal cord, the brachial plexus runs along the axilla, and then the inner side of the arm and forearm down to the hand. Ulnar nerve entrapment can occur anywhere along the nerve’s length through the elbow and arms, or even distally in the hand or wrist at Guyon’s canal. The most frequent location is nerve entrapment at the elbow, which is usually caused by cubital tunnel syndrome.

Ulnar nerve entrapment is the second most common peripheral compression neuropathy. The first, occurring much more frequently, is carpal tunnel syndrome. Carpal tunnel syndrome should not, however, be confused with cubital tunnel syndrome. The syndromes are similar, both involving nerve compression at the arm, however cubital tunnel syndrome affects the ulnar nerve, while carpal tunnel syndrome affects the median nerve.

What causes ulnar nerve entrapment?

A common type of ulnar nerve entrapment at the elbow is cubital tunnel syndrome, which can be caused by elbow injuries (e.g. fractures and dislocations), bone and joint disease (e.g. arthritis and bone spurs), repeated bending of the elbow (which is more common in some occupational settings requiring heavier work), or excessive leaning on it—especially on hard surfaces. Moreover, some conditions can increase susceptibility to nerve compression, such as diabetes and hereditary neuropathy with pressure palsies (HNPP). Occasionally, there is no clear cause leading to ulnar nerve entrapment at the elbow. 

Ulnar nerve entrapment at the wrist can be caused by direct trauma, laceration, ganglion cysts and ulnar tunnel syndrome (AKA Guyon's canal syndrome). Additionally, distal vascular anomalies or some joint conditions—such as rheumatoid arthritis and other disorders—may also contribute to nerve compression. Lastly, cycling and doing excessive push-ups, as well as any other usual causes of chronic and repeated external pressure by hand tools or cane handles, may also contribute to ulnar nerve entrapment at the wrist. 

What are the symptoms of ulnar nerve damage?

Symptoms of ulnar nerve entrapment may vary depending on the location, extent, and severity of the pressure on the nerve, as well as the ulnar nerve branches that are involved. Typical symptoms can include muscle weakness, decreased grip strength, and clumsiness. Some cases could also lead to muscle wasting. Moreover, ulnar nerve entrapment can lead to numbness, tingling (paresthesia), and pain involving the little finger, ring finger, and the palmar aspect of the hand (hypothenar eminence). Severe cases of ulnar nerve damage at the elbow could result in clawing of the fourth and fifth fingers. Over time, ulnar nerve damage may potentially worsen up to the point of permanent disability.

Many people often experience a characteristic tingling sensation when hitting their funny bone. The funny bone, known anatomically as the medial epicondyle of the elbow, is a protuberance in the lower inner part of the humerus. Striking the funny bone can be not so funny, and can actually hurt in some instances, as the ulnar nerve is exposed in that area and vulnerable to transient trauma.

How long does ulnar nerve entrapment last?

When you hit your “funny bone” in the elbow, tingling sensations will probably pass within seconds or minutes. On the other hand, symptoms of ulnar nerve entrapment can be chronic, lasting for long periods of time. If symptoms worsen or persist for more than 2–3 months before or after non-surgical treatment, you should schedule an appointment to see a physician.

How do you diagnose ulnar nerve entrapment?

Diagnosis of ulnar nerve entrapment starts by taking a medical history, followed by physical examination of the arm, elbow, and hand to test for motor and sensory performance, as well as to find the source of injury. Additional tests, including ultrasound, electromyography, and nerve conduction studies can be performed to confirm diagnosis and help determine the location and extent of nerve damage. The two latter techniques are non-invasive electrodiagnostic methods that can be used to evaluate the electrical activity of muscles or neurons, respectively.

How do you treat ulnar nerve entrapment?

Mild cases of ulnar nerve entrapment may resolve spontaneously without treatment. In some cases, pain and inflammation can be treated with medications such as nonsteroidal anti inflammatory drugs (NSAIDs). Other pain medications that may be prescribed include tricyclic antidepressants, especially for individuals who cannot take NSAIDs

Specific movements and positions should be avoided. For example, physicians may instruct to try not to bend your elbow for a long period of time, and you may even wear a splint to help with joint immobilization. In addition, your doctor may recommend physical therapy, such as nerve gliding exercises. 

If symptoms don’t resolve, or they worsen or persist for more than three months, surgical decompression and various surgical approaches can be performed. 

What kind of doctor treats ulnar nerve entrapment?

Many nerve injuries and disorders are first recognized and treated by neurologists, neuromuscular specialists, orthopedists, or physical therapists. If surgery is needed for treatment, it is generally performed by a neurosurgeon who specializes in peripheral nerve surgery.

What are the most important facts to know about ulnar nerve entrapment?

Ulnar nerve entrapment is a compressive neuropathy that occurs when the ulnar nerve is trapped or compressed, and can lead to progressive damage. Ulnar nerve entrapment can present symptoms like pain, weakness, numbness, and tingling sensations involving the little finger, ring finger, and hypothenar eminence. Mild cases may resolve spontaneously. Treatment options include pain medications, physical therapy, and immobilization. If symptoms aren’t resolved, worsen, or persist for more than three months, ulnar nerve entrapment can be treated with surgery.

Related links

Brachial plexus
Klumpke paralysis
Carpal tunnel syndrome
Anatomy clinical correlates: Upper limb

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