Cubital tunnel syndrome describes when the ulnar nerve, or funny bone, becomes stretched, compressed, or irritated. It may cause a person to experience numbness in the wrist, hand, or fingers.
As this nerve covers the entire length of the arm, there are several areas where irritation may occur. One of the most common sites is at the elbow in the cubital tunnel. The cubital tunnel refers to a small passageway of muscle, ligament, and bone on the inside of the elbow through which the ulnar nerve passes.
Although the cause of cubital tunnel syndrome is not always known, it may be due to repetitive movements or putting too much pressure or tension on the nerve. Health experts may also refer to this condition under different names, such as ulnar nerve entrapment, Guyon’s canal syndrome, bicycler’s neuropathy, handlebar palsy, or tardy ulnar palsy.
In this article, we discuss the symptoms of cubital tunnel syndrome and the treatment options that may provide relief.
Sometimes, people also call the ulnar nerve the funny bone nerve. Where the ulnar nerve crosses the elbow, there is very little fat and subcutaneous tissue, meaning the nerve is closer to the surface of the skin and more sensitive. Hence, if a person hits their inner elbow, the sensation can resemble an electric shock.
Most people with cubital tunnel syndrome experience symptoms that may include:
- numbness, pain, and weakness in the arm, forearm, or fingers
- weakened or reduced grip
- waking at night from pain or numbness in the hands or fingers, especially the little and ring fingers
- difficulty bending and straightening the fingers
- difficulty manipulating things with the hands or fingers
- muscle loss at the base of the thumb and first finger
The symptoms of cubital tunnel syndrome usually get much worse when the elbow remains bent or compressed for a long time.
A direct cause may not always be obvious because many factors can contribute to this discomfort. Potential causes of cubital tunnel syndrome include:
- Pressure: The cubital tunnel is a very narrow space with little soft tissue covering it. As a result, the ulnar nerve is very susceptible to direct pressure, such as leaning on the arm on a firm surface. This pressure can compress the nerve and lead to numbness in the ring and little fingers.
- Stretching: Similarly, due to the way the nerve passes through the cubital tunnel, it is also vulnerable to stretching. If a person keeps their elbow bent for a long time, such as during sleep, this can stretch the nerve behind the elbow.
- Anatomy: The elbow joint is a junction for many nerves and blood vessels in the upper extremities of the body. As such, crowding in this area can put extra pressure on the ulnar nerve. Additionally, the ulnar nerve may not stay in place during movement and can instead snap back and forth over a bony lump in the elbow, causing irritation.
Certain activities or previous injuries may also put people at a higher risk of developing cubital tunnel syndrome. These may include:
- repetitive or prolonged movements that involve bending or flexing the elbow
- previous fracture or dislocation of the elbow
- swollen elbow joint
- cysts near the elbow joint
- bone spurs or arthritis of the elbow
For many people with cubital tunnel syndrome, a doctor will prescribe a splint or padded elbow brace to wear at night. Wearing a rigid brace will help a person keep their arm straight and prevent bending, which may cause discomfort. Additionally, a doctor may advise anti-inflammatory medications to help reduce swelling.
People whose symptoms are severe or last longer than 6 weeks should consult a doctor. If symptoms are extreme, chronic, or do not respond to other forms of treatment, surgery may be necessary. Doctors may recommend surgery for people experiencing muscle loss or weakness in their hand because of cubital tunnel syndrome.
A surgeon may recommend one of the following procedures:
- Cubital tunnel release: The surgeon opens the cubital tunnel to increase its size in order to relieve pressure to the affected nerve.
- Ulnar nerve anterior transposition: The surgeon moves the nerve from behind the bony bump, the medial epicondyle, in the elbow to in front of the bump. This procedure prevents the nerve from rubbing against the bump.
- Medial epicondylectomy: A surgeon removes part of the bony bump in the elbow preventing the nerve from rubbing against the bump.
It may take 3–6 weeks to recover fully from surgery for cubital tunnel syndrome, and most people require physical therapy afterward.
Several at-home treatments may provide some relief from the symptoms of cubital tunnel syndrome.
Initially, people may find relief by resting and avoiding actions that aggravate symptoms, such as:
- sleeping with the affected elbow bent
- holding a phone for a long time
- typing for extended periods
- holding a book or tablet up for a long time
- sitting with the arms on an armrest for a long while
- leaning on the elbow
- driving for a long time
- driving with the arm resting on an open window
Additional home treatments that may help include:
- resting the arm and elbow when possible
- wrapping the impacted arm loosely with padding, such as a cloth, towel, or pillow, or wearing an elbow splint at night to prevent the elbow from bending
- taking over-the-counter (OTC) anti-inflammatory medications, such as aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs)
- adjusting computer or writing workspaces so that the chair is not lower than the tabletop
- wearing an elbow pad during the day to provide protection
- avoiding clothing or sports equipment that compresses the elbow
- warming up thoroughly before exercising
Some health experts believe that certain exercises that encourage the ulnar nerve to glide gently through the cubital tunnel may improve symptoms.
People should never hold the positions in cubital tunnel syndrome stretches or exercises. However, they can repeat each nerve gliding and range-of-movement exercise for cubital tunnel syndrome 2–5 times and repeat the exercise a few times each day.
Examples of nerve gliding exercises include:
- Extend the arm straight out in front of the body as far as is comfortable with a straightened elbow and the palm facing up.
- Slowly and gently curl the fingers toward the palm, 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.
- Extend the arm straight out in front of the body with a straightened elbow and the palm facing up.
- Slowly and gently begin to bend the wrist backward, with the palm away from the body.
- If steps 1 and 2 are comfortable, keep the wrist bent back and slowly and gently bend the elbow toward the body, as much as is comfortable, then slowly release it.
- 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 toward the body, as far as is comfortable, and then slowly release the arm.
- Stand with the elbow bent so that the forearm runs parallel to the body.
- Slowly and gently twist the palm upward to face the ceiling and then downward to face the floor.
Doctors may also recommend some range-of-motion exercises for people recovering from cubital tunnel syndrome surgery.
Cubital tunnel syndrome occurs when there is pressure or strain on the ulnar nerve, also known as the funny bone nerve. The symptoms often include numbness, soreness, and weakness.
Treatment may be possible with home remedies and OTC medication, or surgery may be necessary. People with symptoms of cubital tunnel syndrome should consult a doctor if they persist for more than 6 weeks.