Cubital Tunnel Syndrome

What happens in cubital tunnel syndrome

The ulnar nerve runs from the neck down the arm, behind the inner bony bump of the elbow (the medial epicondyle) through a narrow passage called the cubital tunnel, then into the forearm and hand. It supplies feeling to the little finger and half of the ring finger, and controls many of the small muscles of the hand.

Bending the elbow stretches the nerve and narrows the tunnel, raising pressure on the nerve many times over. Keeping the elbow bent for long periods, or leaning on the elbow, reduces blood flow to the nerve and causes symptoms.

Causes and risk factors

• prolonged or repeated elbow bending: sleeping with arms bent, holding a phone, desk work
• leaning on the elbow, such as on a car window or armrest
• the nerve slipping out of its groove (subluxation) when the elbow bends
• previous elbow fracture or dislocation, or arthritis and bone spurs
• cysts or swelling in the area
• diabetes and other conditions that make nerves vulnerable
• heavy manual work and throwing sports

Symptoms

• numbness and tingling in the ring and little fingers, often worse at night or with the elbow bent
• aching on the inner side of the elbow
• weak grip and pinch
• clumsiness, trouble with buttons, typing or playing instruments
• in advanced cases, wasting of the hand muscles, especially between the thumb and index finger, and clawing of the ring and little fingers

Cubital tunnel vs carpal tunnel and other causes

Diagnosis

A doctor will:

• map the numb area and test hand strength
• tap over the nerve at the elbow (Tinel's sign) to see if it causes tingling
• hold the elbow fully bent for a minute to reproduce symptoms
• check for nerve slipping, neck problems and other causes

Tests:

• nerve conduction studies and EMG: confirm the diagnosis, show where the nerve is compressed and how severe the damage is
• ultrasound or MRI: look for nerve swelling, cysts or bony problems
• X-rays: if there was an elbow injury or arthritis
• blood tests: for diabetes or thyroid problems if indicated

Treatment

Non-surgical treatment

Mild to moderate cases often improve within 6 to 12 weeks:

• avoid prolonged elbow bending: use a headset or speakerphone, adjust your workstation so your elbows are relatively straight
• avoid leaning on the elbow; use an elbow pad
• night splint or a towel wrapped around the elbow to keep it from bending more than about 45 degrees while sleeping
• nerve gliding exercises taught by a hand therapist
• anti-inflammatory medicines for elbow pain; follow the label dose

Steroid injections are generally not helpful for cubital tunnel syndrome.

Surgery

Surgery is considered when symptoms persist after about 3 months of non-surgical care, when there is muscle weakness or wasting, or when nerve studies show significant damage. Options:

• in situ decompression: releasing the tissue roof over the tunnel
• anterior transposition: moving the nerve to the front of the elbow so it is not stretched when bending
• medial epicondylectomy: removing part of the bony bump

Numbness often improves within weeks to months after surgery. Weakness and muscle wasting recover more slowly and sometimes incompletely, which is why surgery should not be delayed too long in severe cases.

Outlook

Most people with mild symptoms recover with simple measures. Long-standing compression with muscle wasting may leave some permanent weakness or numbness, even after surgery.

Frequently asked questions

What are the symptoms of cubital tunnel syndrome?

The main symptoms are numbness and tingling in the ring and little fingers, aching on the inside of the elbow, and in more advanced cases weak grip, clumsiness and thinning of hand muscles. Symptoms are often worse when the elbow is bent or at night.

What causes cubital tunnel syndrome?

It is caused by pressure on or stretching of the ulnar nerve at the elbow. Common triggers include keeping the elbow bent for long periods, leaning on the elbow, sleeping with bent arms, previous elbow injury, arthritis and the nerve slipping over the bony bump.

How do you sleep with cubital tunnel syndrome?

Keep your elbows straighter at night. A night splint or a towel loosely wrapped around the elbow stops it bending too much. Avoid sleeping with your hands under your pillow or head. This simple change helps many people within weeks.

Can cubital tunnel syndrome heal on its own?

Mild cases often improve over a few weeks to months by avoiding elbow bending and pressure. If numbness persists, or weakness and muscle thinning appear, see a doctor, because prolonged severe compression can cause permanent nerve damage.

When is surgery needed for cubital tunnel syndrome?

Surgery is usually recommended when symptoms last more than about 3 months despite splints and activity changes, or sooner if there is hand weakness, muscle wasting or significant nerve damage on testing. Surgery relieves pressure on the nerve or moves it.