The cubital tunnel is located in the elbow and is a 4-millimeter passageway between the bones and tissue.
Cubital Tunnel Syndrome is a condition that involves pressure or stretching of the ulnar nerve (also known as the “funny bone” nerve), which can cause numbness or tingling in the ring and small fingers, pain in the forearm, and/or weakness in the hand. The ulnar nerve (Figure 1) runs in a groove on the inner side of the elbow.
Cubital Tunnel Syndrome is a condition characterized by compression of the ulnar nerve in an area of the elbow called the cubital tunnel.
The ulnar nerve travels down the back of the elbow behind the bony bump called the medial epicondyle, and through a passageway called the cubital tunnel. The cubital tunnel is a narrow passageway on the inside of the elbow formed by bone, muscle, and ligaments with the ulnar nerve passing through its center. The roof of the cubital tunnel is covered with a soft tissue called fascia.
When the elbow is bent, the ulnar nerve can stretch and catch on the bony bump. When the ulnar nerve is compressed or entrapped, the nerve can tear and become inflamed leading to a variety of symptoms, called cubital tunnel syndrome.
It encases the ulnar nerve, one of the nerves that supplies feeling and movement to the arm and hand. The ulnar nerve runs from the neck to the shoulder, down the back of the arm, around the inside of the elbow and ends at the hand in the fourth and fifth fingers. Due to the narrow opening of the cubital tunnel, it can be easily injured or compressed through repetitive activities or trauma.
What Is Cubital Tunnel Syndrome?
Cubital tunnel syndrome involves compression of the ulnar nerve between the two bones on the inside of your elbow. Compression of the ulnar nerve causes similar symptoms to when you hit your ‘funny bone’. To discover the exact cause of your cubital tunnel syndrome you will need a diagnostic ultrasound scan.
One common cause of cubital tunnel syndrome is due to the nerve ‘flicking’ over the bone, this can be sometimes be felt if you bend your elbow. Cubital tunnel syndrome is common in those with manual jobs, weight lifters and if you have hypermobility syndrome. Most cubital tunnel symptoms settle with rest, however if they do not reduce, an ultrasound guided steroid injection to bathe the nerve can significantly help your symptoms. Certainly, one injection should be carried out before considering surgery.
Cause
In many cases of cubital tunnel syndrome, the exact cause is not known. The ulnar nerve is especially vulnerable to compression at the elbow because it must travel through a narrow space with very little soft tissue to protect it.
Common Causes of Compression
There are several things that can cause pressure on the nerve at the elbow:
- When your bend your elbow, the ulnar nerve must stretch around the boney ridge of the medial epicondyle. Because this stretching can irritate the nerve, 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 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.”
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
What Are The Symptoms?
Numbness or tingling of the little and ring fingers are usually the earliest symptom. It is frequently intermittent, but may later become constant. Often the symptoms can be provoked by leaning on the elbow or holding the elbow in a bent position (e.g. on the telephone). Sleeping with the elbow habitually bent can also aggravate the symptoms.
In the later stages, the numbness is constant and the hand becomes weak. There may be visible loss of muscle bulk in severe cases, particularly noticeable on the back of the hand between the thumb and first finger, with loss of strength and dexterity.
Investigations may include x-rays of the elbow and nerve conduction studies.
Early symptoms of cubital tunnel syndrome include:
- Pain and numbness in the elbow
- Tingling, especially in the ring and little fingers
More severe symptoms of cubital tunnel syndrome include:
- Weakness affecting the ring and little fingers
- Decreased ability to pinch the thumb and little finger
- Decreased overall hand grip
- Muscle wasting in the hand
- Claw-like deformity of the hand
If you have any of these symptoms, your doctor may be able to diagnose cubital tunnel syndrome by physical examination alone. They also may order a nerve conduction study and a test called electromyography. Electromyography is a procedure in which electrodes placed into muscles and on the skin measure the health of muscles and the nerve cells that control them, to confirm the diagnosis, identify the area of nerve damage, and determine the severity of the condition.
How Is Cubital Tunnel Syndrome Diagnosed?
In addition to a complete medical history and physical exam, diagnostic tests for cubital tunnel syndrome may include:
Nerve conduction test. This test measures how fast signals travel down a nerve to find a compression or constriction of the nerve.
Electromyogram (EMG). This test checks nerve and muscle function and may be used to test the forearm muscles controlled by the ulnar nerve. If the muscles don’t work the way they should, it may be a sign that there is a problem with the ulnar nerve.
X-ray. This is done to look at the bones of the elbow and see if you have arthritis or bone spurs in your elbow.
How Is Cubital Tunnel Syndrome Treated?
Unless your nerve compression has caused a lot of muscle wasting, your doctor will most likely first recommend nonsurgical treatment.
Nonsurgical Treatment
Nonsteroidal anti-inflammatory medicines. If your symptoms have just started, your doctor may recommend an anti-inflammatory medicine, such as ibuprofen, to help reduce swelling around the nerve.
Although steroids, such as cortisone, are very effective anti-inflammatory medicines, steroid injections are generally not used because there is a risk of damage to 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.
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 most often done on an outpatient basis, but some patients do best with an overnight stay at the hospital.
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.
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.
Ulnar nerve anterior transposition. In many 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 prevents it from getting caught on the bony ridge and stretching 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), or within the muscle (intermuscular transposition), or under the muscle (submuscular transposition).
Medial epicondylectomy. Another option to release the nerve is to remove part of the medial epicondyle. Like ulnar nerve transposition, this technique also prevents the nerve from getting caught on the boney ridge and stretching when your elbow is bent.
The Best Exercises for Cubital Tunnel Syndrome
There is no consensus on this question. Some health experts believe certain exercises that encourage the ulnar nerve to glide gently through the cubital and Guyon’s canals may improve symptoms.
The cubital canal is the small channel that the ulnar nerve runs through along the inside of the elbow. Guyon’s canal is where the ulnar nerve runs into the hand through the wrist.
Examples of nerve gliding exercises include:
Exercise 1
- Extend the arm straight out in front of the body with a straightened elbow, as much as is comfortable, with the palm facing up.
- Slowly and gently curl the fingers towards the palms then slowly and gently bend them down, away from the body.
- Slowly and gently bend the elbow, as much as is comfortable, and then slowly release back.
Exercise 2
- Extend the arm straight out in front of the body with a straightened elbow, as much as is comfortable, with the palm facing up.
- Slowly and gently begin to bend the elbow towards the body while at the same time gently twisting the wrist backward, away from the body.
- If steps 1 and 2 are comfortable, then keeping the wrist bent back, slowly and gently bend the elbow, as much as is comfortable, then slowly release it.
Exercise 3
- Stand, sit, or lie down and extend the arm out straight alongside the body with a slightly clenched fist.
- Slowly and gently bend the elbow, bringing the fist towards the body, as far as comfortable, and then slowly release.
Exercise 4
- Stand with the elbow bent so that the forearm runs parallel to the body.
- Slowly and gently twist the palms upwards to face the ceiling and then downwards to face the floor.
People should never hold the positions in cubital tunnel syndrome stretches or exercises.
However, they can repeat nerve gliding and range of movement exercises for cubital tunnel syndrome 2 to 5 times each a few times each day.
Doctors can sometimes recommend some range of movement exercises for people recovering from cubital tunnel syndrome surgery.
