Carpal Tunnel Syndrome

What it is

Carpal tunnel syndrome is pressure on the median nerve as it passes through the carpal tunnel, a narrow, rigid space at the wrist formed by the wrist bones and a thick ligament across the palm side. The nerve shares the tunnel with nine tendons that bend the fingers and thumb. It provides feeling to the thumb, index, middle, and half of the ring finger, and powers muscles at the base of the thumb.

What causes it

Anything that raises pressure inside the tunnel, most often swelling, can squeeze the nerve. The exact cause is usually unknown. Contributing factors include inflammatory arthritis, a previous wrist fracture, cysts, and repetitive activities. It is more common in women, becomes more common with age, and is associated with diabetes, thyroid disease, obesity, and pregnancy.

Symptoms

• Numbness or tingling in the thumb, index, middle, and part of the ring finger
• Symptoms that are worse at night, or waking up to shake the hand out
• Numbness while driving, reading, or holding a phone
• Dropping things or a weak pinch
• In advanced cases, constant numbness and shrinking of the muscles at the base of the thumb

Diagnosis

Carpal tunnel syndrome can usually be diagnosed from your history and a careful examination, including tests that press on or position the nerve. A nerve conduction study (EMG) or ultrasound may be used to confirm the diagnosis, gauge severity, or rule out other causes of numbness such as a pinched nerve in the neck.

Treatment

Without surgery: a night splint that keeps the wrist straight, avoiding positions that bring on symptoms, anti-inflammatory medication, and a corticosteroid injection. These work best when symptoms are mild or recent.

Surgery: carpal tunnel release divides the ligament over the tunnel to take pressure off the nerve. It is a reliable outpatient procedure.

Recovery

Moving the fingers right after surgery helps limit stiffness, swelling, and scar tissue. People with less physically demanding jobs often return to work within days; heavier work can take weeks. The scar may change in color, firmness, and tenderness over the first several months, which is normal.

Results are best when carpal tunnel is treated early, when symptoms first start. When numbness is already severe and constant, results are less predictable, but treatment can keep the problem from getting worse.