Cubital Tunnel Syndrome
Cubital Tunnel Syndrome is a condition that involves compression or stretching of the ulnar nerve (also known as the “funny bone” nerve) at the elbow. Compression or stretching of the nerve can cause numbness or tingling in the ring and little finger side of the hand. Forearm pain and hand weakness may also happen. The ulnar nerve (Figure 1) runs in a groove on the inner side of the elbow, closest to the body.
Causes
There are different causes of this problem. These include:
- Compression: This nerve specifically has little padding or protection over it. Direct pressure (like leaning the arm on an arm rest) can press the nerve. This can result in tingling, numbness, or dullness of feeling. Usually if you move your arm to a better position, it goes away, but in some people, it stays and causes long lasting discomfort, especially while they are sleeping.
- Stretching: Keeping the elbow bent for a long time can stretch the nerve behind the elbow. This can happen when holding a book or phone, or when sleeping with the elbow bent.
- Anatomy: In some cases, the nerve snaps back and forth (out of the groove) during elbow motion. This can irritate the nerve. Sometimes, the soft tissues over the nerve become thicker. Or there is an “extra” muscle over the nerve that can keep the nerve from working correctly. A cyst (ganglion) in the groove can put pressure on the nerve. Sometimes, bone spurs from elbow arthritis put pressure on the nerve. The swelling of joint tissue in rheumatoid arthritis can also apply pressure. Pressure from ligaments on the nerve before or after the tunnel can be a cause.
- Trauma: Direct blow, fractures, puncture, bleeding into the tunnel
- Other medical conditions: Rheumatoid arthritis, diabetes
Signs and Symptoms
The most common symptoms of cubital tunnel or ulnar nerve disorders are long-lasting pain, dullness of sensation, numbness, tingling and/or weakness. Pain is usually in the medial forearm or elbow. There is not numbness/tingling in the forearm or elbow since those are different nerves. For the ulnar nerve, there is numbness/tingling in the front (palm) and back of the hand but only on the little finger side. It does not involve the thumb side of the hand because those are different nerves. It also affects the front and back of the little finger. The side of the ring finger next to the little finger is also commonly affected. If the numbness/tingling involves the forearm, thumb, index, or long fingers, a different condition is likely.
Frequently, the symptoms are mild at first, with only tingling/numbness. When the pressure is more severe, then the motor fibers of the nerve may be affected. Clumsiness can result from poor sensation. It can also be from weakness of the small hand muscles (intrinsic muscles) supplied by the ulnar nerve.
Diagnosis
The diagnosis is often suspected from getting a history and physical exam. Symptoms from leaning on the elbow or from flexing the elbow are often a clue. Having an accurate description of where the numbness/tingling is located is helpful. This is because there are other conditions which may produce similar areas of numbness/tingling. For example:
- A pinched nerve in the neck can cause numbness/tingling in the little finger, both sides of the ring finger, and the ulnar side of the hand. However, there may also be numbness along the medial forearm.
- Diabetes is often associated with ulnar nerve compression at the elbow. But there may be numbness in other areas from a diabetic neuropathy.
- Patients with fibromyalgia often complain of numbness/tingling in the upper limb. This is usually not due to nerve pressure in the upper limb. There may be simply dullness rather than true numbness. The sensory loss area is often not typical of that served by a nerve in the elbow/forearm/hand.
A detailed physical exam is recommended for making the clinical diagnosis. Ideally, this would include:
- A detailed sensory exam, often requiring only a light touch. Identifying the exact area of abnormal sensation helps to tell the difference between an ulnar nerve compression versus other conditions causing numbness/tingling. The exam may include testing the whole hand, all digits, and the front and back of the hand and the forearm.
- The muscles supplied by the ulnar nerve may be affected. Testing may reveal weakness of:
- The muscles that flex the small joints of the ring and little fingers (forearm muscles).
- The hand muscles that spread the fingers or bring them together (intrinsic muscles). Weakness of these may also cause a “clawing” posture of the ring and small fingers. And the posture of your thumb and finger when you pinch them together may be abnormal (Froment’s test).
- Tests that result in repoducting numbness/tingling include:
- Bending the elbow while your surgeon puts pressure on the ulnar nerve just above the elbow (elbow flexion test).
- Tapping over the ulnar nerve at the elbow causing symptoms in the ring and little fingers (Tinel’s test). This may be tested on the opposite elbow.
Sometimes nerve tests are also ordered. These may include testing only the nerves (NCS). Another common test exams muscle function (EMG). These can help to find out if other conditions may be causing the symptoms in the hand. After treatments for ulnar nerve compression, these tests can be repeated to monitor improvement.
Treatment
There are many and varied ways of treating cubital tunnel syndrome. These involve surgery or no surgery.
Examples of non-surgical treatment include:
- Avoiding activities which cause numbness/tingling, such as:
- Leaning on the elbow
- Bent elbow activities, like holding a phone or book
- Splinting, especially at night to avoid a bent elbow. This can be done with a pillow or towel wrapped about the elbow.
- Physiotherapy of different types
- Simple decompression is a release of the tunnel over the nerve. This is to relieve pressure. This can be done with an open surgery or through a scope (endoscope).
- Moving the nerve to a place in front of the elbow is called transposition. It takes care of relieving pressure and stretching. Examples include:
- The least commonly used surgery is called medial epicondylectomy. It removes the bone at the elbow over which the nerve passes in the tunnel. This is a pressure releasing surgery. It has a higher rate of complications than other surgeries.
The outcome of your treatment may vary depending on your condition and your treatment. Your outcome could include:
- Complete recovery with no further symptoms. This is most common when the numbness before treatment was intermittent (coming and going).
- Improvement of symptoms, but with some remaining numbness/tingling and/or weakness.
- The condition remains the same despite treatment. This is more common when the numbness before treatment was constant, with or without weakness.
- The condition becomes worse, even with treatment (often called “recurrent”).
Hand Therapy
Specialized hand therapy can be beneficial with cubical tunnel syndrome. Gentle, specific ulnar nerve and tendon gliding exercises are used to promote mobility conservatively or following surgery.Patients are educated on gentle range of motion exercises to decrease pressure on nerve and promote healing.Activity modifications, including work station evaluations, will be taught, which candecrease positions that add compression to the ulnar nerve at the elbow. Hand therapists also fabricate custom orthoses to promote mobility of the fingers in the case of severe nerve damage, which maximizes healing following surgery.
Even with the most appropriate and successful treatments, improvement may take months to get the best results. Consult your hand surgeon for the best treatment plan for you.
© 2023 American Society for Surgery of the Hand.This content is written, edited and updated by hand surgeon members of the American Society for Surgery of the Hand. Find a hand surgeon near you.