Carpal Tunnel Syndrome

Carpal tunnel syndrome occurs when the median nerve is compressed where it passes through a narrow channel at the wrist, the carpal tunnel. The tunnel is rigid and cannot expand, so anything that raises pressure inside it, such as swelling, fluid retention, or holding the wrist bent for long stretches, presses on the nerve. At first the pressure irritates the nerve's outer insulation; with sustained pressure the nerve fibers themselves can be damaged. It is a common condition, more often affecting women than men, and most people do well with treatment, though long-standing or severe cases may not fully recover.

Common symptoms include:

• Numbness and tingling in the thumb, index, middle, and thumb side of the ring finger
• Symptoms worst at night, often waking you, with shaking the hand bringing relief
• Tingling during the day when the wrist stays bent, such as driving or holding a phone
• Fumbling with buttons, dropping small objects, or trouble with fine pinch tasks
• In advanced cases, flattening of the muscle pad at the base of the thumb

Most of the time the diagnosis is made in the exam room, checking sensation in the fingertips and the strength of the muscles at the base of the thumb. When the picture is unclear or surgery is being considered, nerve conduction studies and EMG confirm the diagnosis, grade its severity, and rule out other causes such as a pinched nerve in the neck. Ultrasound can show swelling of the nerve in selected cases.

Nonsurgical care is the starting point for mild-to-moderate cases:

• A night splint that holds the wrist straight to prevent the bend that drives nighttime numbness
• Activity and ergonomic changes to keyboard, mouse, and grip habits
• A corticosteroid injection into the tunnel for temporary relief, which can be repeated
• A short course of anti-inflammatory medication during a flare

Carpal tunnel release is considered when the case is already severe, when nonsurgical care has not worked, or when symptoms return promptly after an injection. The procedure cuts the ligament forming the roof of the tunnel to create more room for the nerve and reliably relieves tingling and nighttime symptoms.

• Carpal tunnel releaseHand & Wrist

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

• Carpal Tunnel Syndrome — AAOS OrthoInfo