Cubital Tunnel Syndrome

Cubital tunnel syndrome is compression of the ulnar nerve at the elbow, where it passes through a narrow channel on the inner side just behind the spot people call the funny bone. The tunnel is tightest when the elbow is bent, so prolonged bending, direct pressure on the inner elbow, or narrowing of the space can squeeze the nerve. When the nerve cannot carry signals well, it shows up as tingling and numbness in the ring and small fingers, aching along the inner elbow, and, in more advanced cases, weakening of the small hand muscles. How well it responds depends on how long and how severely the nerve has been under pressure.

Common symptoms include:

• Numbness and tingling in the ring and small fingers, worst when the elbow stays bent
• Symptoms that wake you at night when the arm is folded
• Aching or tenderness along the inner side of the elbow
• Weaker grip and pinch, with trouble opening jars or turning keys
• In advanced cases, visible muscle wasting in the hand, with the ring and small fingers beginning to claw into a bent position

Cubital tunnel syndrome is usually diagnosed from your symptoms and a focused exam that checks tenderness over the nerve, sensation in the ring and small fingers, and grip and pinch strength. When the diagnosis is unclear or surgery is being considered, nerve conduction studies and EMG confirm the compression and grade its severity. X-ray or MRI is sometimes added if a bone spur, cyst, or prior injury may be contributing.

Most people improve with nonsurgical measures that take pressure off the nerve:

• An elbow extension splint worn at night to keep the elbow straight, often the most effective single change
• Activity changes to avoid prolonged bent-elbow positions and leaning on the inner elbow
• A padded sleeve over the inner elbow during the day to cushion the nerve
• Anti-inflammatory medication for short-term relief during a flare

Surgery is considered when symptoms persist despite a real trial of these measures, when nerve studies show moderate to severe compression, or when the hand muscles start to weaken. The goal is to give the nerve more room, and in some cases the nerve is moved to the front of the elbow so it no longer catches.

For a fuller explanation, including anatomy, diagnosis, and the full range of treatment:

• Ulnar Nerve Entrapment at the Elbow — AAOS OrthoInfo