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Common Causes of Compression

There are several things that can cause pressure on the nerve at the elbow:

• When you bend your elbow, the ulnar nerve must stretch around the bony ridge of the medial epicondyle. Because this stretching can irritate the nerve and decrease its blood supply, keeping your elbow bent for long periods or repeatedly bending your elbow can cause painful symptoms. For example, many people sleep with their elbows bent, which can aggravate symptoms of ulnar nerve compression and cause you to wake up at night or in the morning with your fingers asleep.
• In some people, the nerve slides out from behind the medial epicondyle when the elbow is bent. Over time, this sliding back and forth may irritate the nerve.
• Leaning on your elbow for long periods of time can put pressure on the nerve.
• Fluid buildup in the elbow can cause swelling that may compress the nerve.
• A direct blow to the inside of the elbow can cause pain, electric shock sensation, and numbness in the little and ring fingers. This is commonly called "hitting your funny bone."
• Throwing a baseball puts a large amount of stress on the inside of the elbow and can sometimes lead to ulnar nerve irritation.

Risk Factors

Some factors put you more at risk for developing cubital tunnel syndrome. These include:

• Prior fracture or dislocation of the elbow
• Bone spurs/arthritis of the elbow
• Swelling of the elbow joint
• Cysts near the elbow joint
• Repetitive or prolonged activities that require the elbow to be bent or flexed
• Baseball pitching

Medical History and Physical Examination

Your doctor will discuss your medical history and general health. They may also ask about your work, your activities, and what medications you are taking.

After discussing your symptoms and medical history, your doctor will examine your elbow and hand to determine which nerve is compressed and where it is compressed. The doctor may also do a neck exam, as pinched nerves in the neck can cause similar symptoms.

Some of the physical examination tests your doctor may do include:

• Tap over the nerve at the funny bone. If the nerve is irritated, tapping can cause a shock into the little finger and ring finger (Tinel's sign) — although this can happen when the nerve is normal as well.
• Check whether the ulnar nerve slides out of normal position when you bend your elbow.
• Move your neck, shoulder, elbow, and wrist to see if different positions cause symptoms.
• Check for feeling and strength in your hand and fingers.

To perform Tinel's test for nerve damage, your doctor will lightly tap along the inside of the elbow joint, directly over the ulnar nerve.

Tests

X-rays. X-rays provide detailed pictures of bone. Most causes of compression of the ulnar nerve cannot be seen on an X-ray. However, your doctor may take X-rays of your elbow or wrist to look for bone spurs, arthritis, or other places that the bone may be compressing the nerve.

Nerve conduction studies. These tests can determine how well the nerve is working and help identify where it is being compressed. The test sends an electric current down the arm and looks to see if the current gets slowed along its path. If the current gets slowed down, this is likely an area of nerve compression. This can also help the doctor determine whether the pinched nerve is at the elbow, wrist, or neck. 

Nerves are like electrical cables that travel through your body carrying messages between your brain and muscles. When a nerve is not working well, it takes longer for it to conduct.

Nerve conduction studies can also determine whether the compression is causing muscle damage. During the test, small needles are put into some of the muscles that the ulnar nerve controls. Muscle damage (especially with wasting) is a sign of more severe nerve compression.

Nerve conduction studies measure the signals travelling in the nerves of your arm and hand.

Nonsurgical Treatment

Nonsteroidal anti-inflammatory drugs (NSAIDs). If your symptoms have just started, your doctor may recommend an anti-inflammatory medicine, such as ibuprofen or naproxen, to help reduce swelling around the nerve.

Although steroids, such as cortisone, are very effective anti-inflammatory medicines, steroid injections are generally not used to treat cubital tunnel syndrome because there is a risk of damage to the nerve. However, sometimes your doctor will prescribe a short course of oral steroids (taken by mouth) to help relieve the inflammation around the nerve.

Bracing or splinting. Your doctor may prescribe a padded brace or splint to wear at night to keep your elbow in a straight position. 

Nerve gliding exercises. Some doctors think that exercises to help the ulnar nerve slide through the cubital tunnel at the elbow and the Guyon's canal at the wrist can improve symptoms. These exercises may also help prevent stiffness in the arm and wrist.

Examples of nerve gliding exercises. With your arm in front of you and the elbow straight, curl your wrist and fingers toward your body, then extend them away from you, and then bend your elbow.

Surgical Treatment

Your doctor may recommend surgery to take pressure off of the nerve if:

• Nonsurgical methods have not improved your condition
• The ulnar nerve is very compressed
• Nerve compression has caused muscle weakness or damage

There are a few surgical procedures that will relieve pressure on the ulnar nerve at the elbow. Your orthopaedic surgeon will talk with you about the option that would be best for you.

These procedures are generally done on an outpatient basis (where you go home the same day as your surgery).

Cubital tunnel release. In this operation, the ligament roof of the cubital tunnel is cut and divided. This increases the size of the tunnel and decreases pressure on the nerve.

This illustration shows the path of the ulnar nerve through the cubital tunnel. Structures that may compress the nerve — such as the medial epicondyle and ulnar collateral ligament — are also shown.

Reproduced from J Bernstein, ed: Musculoskeletal Medicine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2003.

After the procedure, the ligament begins to heal, and new tissue grows across the division. The new growth heals the ligament and allows more space for the ulnar nerve to slide through.

Cubital tunnel release tends to work best when the nerve compression is mild or moderate and the nerve does not slide out from behind the bony ridge of the medial epicondyle when the elbow is bent.

In this surgical photo, a cubital tunnel release has been performed to decompress, or relieve pressure on, the ulnar nerve. The arrow shows the portion of the nerve that has become narrowed over time due to compression.

Ulnar nerve anterior transposition. In most cases, the nerve is moved from its place behind the medial epicondyle to a new place in front of it. Moving the nerve to the front of the medial epicondyle keeps it from getting caught on the bony ridge and stretching when you bend your elbow. It allows a more direct path for the nerve and removes the compression on the nerve when you bend your elbow. This procedure is called an anterior transposition of the ulnar nerve.

The nerve can be moved to lie:

• Under the skin and fat but on top of the muscle (subcutaneous transposition)
• Within the muscle (intermuscular transposition)
• Under the muscle (submuscular transposition)

For anterior transposition of the ulnar nerve, an incision is made along the inside of the elbow (pictured) or along the back side of the elbow.

Surgical Recovery

• Depending on the type of surgery you have, you may need to wear a splint for a few days to weeks after the operation. A submuscular transposition usually requires a longer time (3 to 6 weeks) in a splint.
• Most patients are allowed to move their elbow right away to prevent any scarring of the nerve.
• While motion often starts immediately, you will avoid any heavy lifting with the arm for a few weeks.
• Your surgeon may recommend physical therapy exercises to help you regain strength and motion in your arm. They will also talk with you about when it will be safe to return to all your normal activities.

Surgical Outcome

The results of surgery are generally good. Each method of surgery has a similar success rate for routine cases of nerve compression.

If the nerve is very badly compressed or if there is muscle wasting, the nerve may not be able to return to normal, and some symptoms may remain even after the surgery. Nerves recover slowly, and it may take a long time to know how well the nerve will do after surgery.