Carpal Tunnel Syndrome

What the carpal tunnel is

The carpal tunnel is a narrow passage on the palm side of the wrist, formed by the small wrist bones and a tough band across the top (the transverse carpal ligament). Nine tendons that bend the fingers and the median nerve pass through it. The median nerve supplies feeling to the thumb, index, middle and the thumb side of the ring finger, and powers some thumb muscles.

Anything that swells the tissues or narrows the tunnel squeezes the nerve. At first, this reduces its blood supply and causes tingling. With longer pressure, the nerve's insulation and then the nerve fibers are damaged, causing constant numbness and weakness.

Carpal tunnel symptoms

• numbness, tingling or "pins and needles" in the thumb, index, middle and half of the ring finger; the little finger is spared
• symptoms at night or on waking; people often shake or flick their hand to relieve it
• symptoms triggered by holding a phone, book, steering wheel or bicycle handlebars
• aching or pain in the wrist and palm that can spread up the forearm
• clumsiness, dropping things, trouble with buttons or fine tasks
• in advanced cases, wasting of the thenar muscles at the base of the thumb and constant numbness

If the little finger is numb, consider cubital tunnel syndrome (ulnar nerve compression at the elbow) or a neck problem.

Causes and risk factors

Most cases have no single cause. Contributing factors:

• female sex: women are about three times more likely to be affected, possibly because of a smaller tunnel
• pregnancy: fluid retention causes CTS in many pregnant women, usually resolving after birth
• diabetes and other causes of nerve damage
• hypothyroidism
• obesity
• rheumatoid arthritis and other inflammatory arthritis causing tendon sheath swelling
• wrist fractures and arthritis that change the shape of the tunnel
• work involving forceful, repetitive gripping or vibrating tools; evidence linking ordinary keyboard use is weak
• kidney failure on dialysis, amyloidosis, acromegaly
• genetics: it often runs in families
• age: most common between 40 and 60

How carpal tunnel syndrome is diagnosed

Clinical tests

• Tinel's sign: tapping over the nerve at the wrist causes tingling in the fingers.
• Phalen's test: holding the wrists fully bent, backs of hands together, for 60 seconds reproduces symptoms.
• Carpal compression test: pressing over the tunnel for 30 seconds reproduces symptoms.
• Checking sensation, thumb strength and muscle bulk.

The hand diagram (marking where symptoms occur) and the pattern of night symptoms are among the most useful clues.

Tests

• Nerve conduction studies and electromyography (EMG): measure how fast signals travel through the median nerve; confirm the diagnosis, grade severity and rule out other nerve problems.
• Ultrasound: can show a swollen median nerve.
• Blood tests for diabetes and thyroid function if there are other clues.

Treatment

Non-surgical treatment

For mild to moderate symptoms:

• Night wrist splints that hold the wrist straight (neutral) reduce pressure during sleep. Wear them every night for at least 4 to 6 weeks.
• Activity changes: take breaks from repetitive gripping, keep the wrist straight, use padded tools and avoid leaning on the wrist.
• Steroid injection into the carpal tunnel can give relief for weeks to months and helps confirm the diagnosis.
• Oral steroids for a short course help some people.
• Treat underlying conditions such as hypothyroidism or diabetes.
• Nerve and tendon gliding exercises may help some people as part of a program with a hand therapist.

Over-the-counter painkillers such as ibuprofen do little for the nerve symptoms themselves. Diuretics, vitamin B6 and magnets have not been shown to help.

Surgery

Carpal tunnel release cuts the transverse carpal ligament to enlarge the tunnel. It is done under local anesthetic as an outpatient procedure, either through a small open incision in the palm or endoscopically. It is recommended for:

• constant numbness, weakness or thumb muscle wasting
• moderate to severe changes on nerve studies
• symptoms that persist despite splinting and injection

Surgery relieves symptoms in most people. Night tingling often improves within days. Grip strength returns over a few months, and scar tenderness in the palm can last a few months. Severe, long-standing numbness may not fully recover, which is why treating persistent symptoms promptly matters.

Carpal tunnel syndrome in pregnancy

CTS is common in the third trimester because of fluid retention. It usually improves within weeks to months after delivery. Night splints are the main treatment; steroid injections can be used if needed. Surgery is rarely necessary.

Prevention

There is no proven way to prevent CTS, but these may reduce strain:

• keep wrists in a neutral position when typing and using tools
• reduce force and take regular breaks during repetitive tasks
• keep hands warm
• manage weight, diabetes and thyroid conditions

Frequently asked questions

What are the first signs of carpal tunnel syndrome?

Early signs are tingling, numbness or burning in the thumb, index and middle fingers, especially at night or when holding a phone or steering wheel. Many people wake and shake their hand to get relief. The little finger is not affected.

Why is carpal tunnel worse at night?

Many people sleep with their wrists bent, which narrows the tunnel and increases pressure on the median nerve. Fluid also redistributes when lying down. A splint that keeps the wrist straight at night often relieves symptoms within weeks.

Can carpal tunnel go away on its own?

Mild cases, especially in pregnancy or after a temporary increase in hand use, can improve with time and splinting. Long-standing or severe carpal tunnel syndrome usually does not resolve without treatment, and untreated nerve compression can cause permanent numbness and weakness.

How long does it take to recover from carpal tunnel surgery?

Most people use the hand for light tasks within days. Night tingling often improves quickly. Grip and pinch strength usually return over 2 to 3 months, and palm tenderness can take a few months to settle. Severe numbness may improve slowly over a year.

Does typing cause carpal tunnel syndrome?

The evidence linking computer and keyboard use to carpal tunnel syndrome is weak. Forceful, repetitive gripping and vibrating tools carry a stronger link. Typing with bent wrists can worsen existing symptoms, so a neutral wrist position and breaks help.