Cubital tunnel syndrome

Cubital tunnel syndrome is pressure on, or stretching of, the ulnar nerve where it passes behind the inner side of the elbow, the spot often called the funny bone. This nerve supplies sensation to the little finger and the neighboring half of the ring finger, and it powers many of the small muscles inside the hand that handle grip and fine motor tasks. It is a common nerve compression problem of the arm.

• Numbness and tingling in the ring and little fingers, which may come and go
• Symptoms that are worse when the elbow stays bent, such as while holding a phone or sleeping with the arm bent
• Waking at night with numb fingers
• Aching on the inner side of the elbow
• Clumsiness, a weaker grip or pinch, and trouble with tasks such as buttoning or typing
• In long-standing cases, thinning of the hand muscles, especially between the thumb and index finger, and fingers that begin to curl

The ulnar nerve has little padding at the elbow, and bending the elbow stretches the nerve and narrows the space it runs through. Often no single cause is found.

Things that can contribute include:

• Keeping the elbow bent for long periods, including during sleep
• Leaning on the elbow, such as on a desk, armrest, or car window ledge
• A nerve that slips out of its groove when the elbow bends
• A previous elbow fracture or dislocation, arthritis, bone spurs, or swelling around the elbow
• A cyst near the nerve
• Repeated throwing or other activities with frequent elbow bending
• Diabetes, which can make nerves more sensitive to pressure

A clinician checks feeling and strength in the hand, taps along the nerve at the elbow, and watches whether the nerve moves out of place as the elbow bends. The neck, shoulder, and wrist are examined as well, because the ulnar nerve can also be pinched at other points along its path, including the wrist.

Nerve conduction studies and electromyography (EMG) show where the nerve is compressed, how severely, and whether the hand muscles are affected. X-rays may be taken to look for arthritis or bone spurs at the elbow.

Mild or intermittent symptoms are usually treated without surgery first.

Non-surgical options:

• Avoiding long periods with the elbow bent, and not leaning on the inner elbow
• Keeping the elbow straighter at night with a splint, an elbow pad worn backward, or a towel wrapped loosely around the arm
• Padding hard surfaces at work or in the car
• Anti-inflammatory medication when appropriate
• Nerve gliding exercises, often taught by a hand therapist

Surgery may be recommended when symptoms continue despite these measures, when testing shows significant compression, or when there is weakness or muscle loss in the hand. Common procedures are:

• Cubital tunnel release: the tissue roof over the nerve is divided to give it more room
• Ulnar nerve transposition: the nerve is moved from behind the elbow to the front of the bony bump on the inner elbow, so it is no longer stretched when the elbow bends

The surgeon chooses an approach based on the examination, how the nerve behaves when the elbow bends, and other findings. These are usually outpatient procedures.

After surgery, the arm may be protected in a dressing or splint for a short time, usually longer after a transposition. Gentle elbow motion generally starts early, and heavier lifting waits several weeks; therapy may help restore strength and motion.

Nerves recover slowly. Tingling may ease sooner, while weakness or long-standing numbness can take many months to change and may not recover fully, particularly when the nerve was severely compressed before treatment.

Avoiding long periods with the elbow sharply bent and not resting your weight on the inner elbow may lower pressure on the nerve, especially if you have had symptoms before.