Causes and Risk Factors
Anything that crowds, swells, or irritates the tissues inside the carpal tunnel can compress the nerve:- Repetitive hand and wrist use: Prolonged or forceful gripping, typing, and vibrating-tool work can aggravate the tendons that share the tunnel.
- Wrist anatomy: Smaller carpal tunnels — more common in women — and prior wrist fractures leave less room for the nerve.
- Medical conditions: Diabetes, hypothyroidism, and inflammatory arthritis that involves the wrist all increase risk.
- Fluid retention: Pregnancy and other causes of swelling can temporarily compress the nerve; symptoms often resolve after delivery.
Symptoms
Symptoms usually start gradually and are often worse at night. Many people first notice them while holding a phone, gripping a steering wheel, or reading in bed:- Numbness and tingling: "Pins and needles" or burning in the thumb, index, and middle fingers — characteristically sparing the little finger.
- Night waking: Many people wake with a numb hand and shake or hang it to restore feeling.
- Weak grip and clumsiness: Dropping objects, difficulty buttoning clothes, or trouble holding a phone or steering wheel.
- Advanced signs: Constant numbness or visible wasting of the muscle at the base of the thumb indicates prolonged compression and needs prompt attention.
Diagnosis
Diagnosis begins with the history and an examination of hand strength and sensation, often including simple provocative tests that tap or flex the wrist to reproduce symptoms. When the picture is unclear or surgery is being considered, nerve conduction studies and electromyography measure how well signals travel through the median nerve and grade the severity. These brief office tests also help rule out look-alike problems, such as a pinched nerve in the neck, which can cause similar tingling in the hand and arm. Your physician may also check for underlying contributors such as thyroid disease or diabetes.Treatment
Treatment depends on severity, and mild-to-moderate cases often respond well without surgery:- Night splinting: A wrist brace worn during sleep keeps the wrist in a neutral position and is the first-line treatment for most people; improvement is often noticeable within a few weeks of consistent use.
- Activity modification: Adjusting workstation ergonomics, taking micro-breaks, and reducing forceful or vibrating tasks lowers daily strain on the nerve.
- Corticosteroid injection: An injection into the carpal tunnel can reduce swelling around the nerve and relieve symptoms, sometimes for months.
- Treating underlying conditions: Better control of diabetes, thyroid disease, or arthritis helps the nerve recover.
- Surgery: Carpal tunnel release — cutting the ligament that roofs the tunnel — is a brief, highly effective outpatient procedure for severe or persistent cases.
What to Expect With Carpal Tunnel Syndrome
Carpal tunnel syndrome is compression of the median nerve as it passes through a narrow channel at the wrist. The symptoms follow that anatomy precisely: numbness and tingling in the thumb, index, middle, and half the ring finger, characteristically worst at night and often relieved by shaking the hand. Symptoms outside that distribution, or involving the little finger, point somewhere else.
Why it wakes you at night
Most people sleep with their wrists flexed, which narrows the tunnel further, and fluid redistributes when lying flat. That combination is why night-time symptoms are the classic presentation and why a neutral wrist splint worn at night is often the single most effective first treatment. It is also the reason people describe hanging the hand out of bed or shaking it awake — both temporarily relieve the pressure.
Treatment usually starts conservatively
Night splinting, activity modification, and treating contributing conditions resolve or substantially improve a meaningful proportion of cases, particularly when symptoms are intermittent and there is no weakness. Corticosteroid injection provides temporary relief and helps confirm the diagnosis. Surgical release is highly effective and is considered when symptoms persist despite conservative measures, when there is constant numbness, or when there is weakness or wasting of the thumb muscles — the last of these should not be watched and waited on, because nerve recovery is less complete once muscle loss has occurred.
Look for what is contributing
Several conditions predispose to carpal tunnel syndrome and are worth identifying, because treating them changes the outcome: hypothyroidism, diabetes, rheumatoid arthritis, pregnancy, and obesity among them. Our musculoskeletal team assesses both the nerve and the contributors. The NINDS carpal tunnel resource and NIAMS cover diagnosis and treatment in more depth.
What the splint should actually look like
A wrist splint for carpal tunnel needs to hold the wrist in a neutral position, not in extension. Many off-the-shelf braces sold for wrist support hold the wrist cocked back, which narrows the tunnel further and makes symptoms worse. A splint with a removable metal stay that can be bent flat, worn at night rather than during the day, is what the evidence supports.
If numbness has become constant, if you are dropping things, or if splinting has not helped after several weeks, schedule a visit rather than waiting — timing affects how completely the nerve recovers.