Cubital Tunnel Syndrome

What it is

Cubital tunnel syndrome is compression or stretching of the ulnar nerve, the “funny bone” nerve, where it runs in a groove on the inner side of the elbow.

What causes it

• Pressure: the nerve has little padding, so leaning on the elbow can compress it
• Stretching: keeping the elbow bent for long periods, such as holding a phone or sleeping with the arm bent
• Anatomy: a nerve that snaps in and out of its groove, thickened tissue, a cyst, or bone spurs
• Injury and medical conditions: fractures, a direct blow, diabetes, or rheumatoid arthritis

Symptoms

• Numbness and tingling in the small finger, the neighboring half of the ring finger, and that side of the hand
• Aching on the inner side of the elbow or forearm
• Clumsiness or weakness of grip and pinch
• In advanced cases, shrinking of the small muscles of the hand

Diagnosis

The diagnosis is based on your history and a detailed examination of sensation and strength. Nerve studies (NCS/EMG) may be ordered to confirm it and rule out other causes, such as a pinched nerve in the neck.

Treatment

Without surgery: avoid leaning on the elbow and long periods with the elbow bent, keep the elbow straighter at night with a splint or a pillow or towel wrapped around it, and therapy. These measures are most effective in mild to moderate cases.

Surgery: a simple decompression releases the tunnel over the nerve, through an incision or with a scope. In some cases the nerve is also moved to the front of the elbow (transposition) to relieve both pressure and stretch. Removing part of the bone at the inner elbow (medial epicondylectomy) is the least common option.

Recovery

Outcomes vary. Complete recovery is most common when numbness came and went before treatment. Constant numbness, with or without weakness, is more likely to remain. Hand therapy with nerve and tendon gliding exercises and workstation changes can help. Even with successful treatment, improvement can take months.