What Is Cubital Tunnel Syndrome?
The ulnar nerve is one of three main nerves in the arm. It starts at the neck and ends in the hand. The nerve can be compressed at several places on its path, but the most common place is at the elbow. When the ulnar nerve is compressed or entrapped at the elbow, the condition is known as cubital tunnel syndrome. Cubital tunnel syndrome is the second most common type of nerve compression (neuropathy) in the upper extremities, after carpal tunnel syndrome.
The elbow is a meeting of three bones: the upper arm bone, called the humerus, and the two forearm bones, the radius and ulna. The ulnar nerve starts in the neck, runs down the inside of the arm and elbow and begins to branch below the elbow while continuing down to the fingers.
At the elbow, the nerve runs through a space called the cubital tunnel, which sits just below the medial epicondyle, a bony outcropping on the humerus. That electric feeling of hitting the “funny bone” occurs after injury to or compression of the ulnar nerve close to the medial epicondyle.
Cubital tunnel syndrome occurs when the cubital tunnel becomes tight or compressed and presses on the ulnar nerve. It can also happen if the nerve slides over the medial epicondyle repeatedly, which irritates the nerve.
Symptoms of cubital tunnel syndrome include:
- Numbness and tingling in the ring and pinky fingers
- Pain on the inside of the elbow
- Weak grip and difficulty with fine motor movements
- Muscle atrophy in the hand, if the nerve has been compressed for a long time
Causes and Risk Factors
Often, it is difficult to pinpoint the exact cause of cubital tunnel syndrome. Factors that increase the risk of cubital tunnel syndrome include:
- Bone spurs in the elbow
- Fluid buildup in the elbow
- Holding the elbow in a flexed position for long periods
- Injury to the elbow
- Occupations that require heavy manual labor, repetitive use of the arms or leaning on the elbow
A medical history and physical examination are typically the first steps in diagnosing cubital tunnel syndrome. The doctor may:
- Tap the funny bone to see if there is a nerve reaction
- Check if the nerve slides around when the elbow is bent
- Move the neck, shoulder, elbow and wrist to see if symptoms appear
- Check the feeling and strength in the hand and fingers
An X-ray, which does not show nerves or soft tissue, may be useful in ruling out conditions like bone spurs or arthritis as the reason for pain. A nerve conduction study can determine how well the nerve is performing by stimulating the nerve in one place and seeing how long it takes for the stimulation to reach farther down the nerve. However, nerve conduction studies can be negative in some people with cubital tunnel syndrome. The longer the duration of the symptoms, the more nerve damage is present.
Conservative methods of treatment are usually tried before surgery in the case of cubital tunnel syndrome. These nonsurgical treatments can include:
- Elbow brace, including night splinting to help avoid excess movement of the elbow
- Exercises to help the nerve slide through the cubital tunnel
- Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen
If these more conservative methods of treatment do not reduce symptoms, surgery may be necessary. There are a number of different surgical options, such as:
- Cubital tunnel release, which aims to widen the cubital tunnel and give the ulnar nerve more room to move. The ligament at the top of the tunnel is cut and divided. The ligament will heal with more room to spare in the tunnel.
- Medial epicondylectomy, where part of the medial epicondyle is removed in order to prevent the nerve from getting caught on it.
- Ulnar nerve anterior transposition, in which the nerve is moved from behind the medial epicondyle to in front of it. This should prevent the nerve from getting stuck on or rubbing against the funny bone. In some patients, the nerve is moved deep to the muscle in front of the medial epicondyle.
The surgeon and the patient will discuss the best approach.
Recovery can occur over weeks or months, with nerve transposition generally having the longest recovery. Outcomes are good, with each form of surgery curing the condition at about the same rate for cases that are not severe. In severe cases with much nerve damage, surgery may not be wholly effective.
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