Carpal tunnel syndrome is a condition where the main nerve running through your wrist gets squeezed inside a narrow passageway, causing numbness, tingling, and weakness in your hand. It affects about 1 to 5% of the population at any given time, and roughly 10% of people will experience it at some point in their lives. It’s the most common nerve compression condition in the body.
What’s Happening Inside Your Wrist
The carpal tunnel is a small channel on the palm side of your wrist, formed by a U-shaped arrangement of small bones with a tough band of tissue (called a ligament) stretched across the top like a roof. Through this tunnel pass nine tendons that bend your fingers, plus the median nerve, which provides feeling to your thumb, index finger, middle finger, and the thumb side of your ring finger.
In a healthy wrist, the pressure inside this tunnel is very low, around 2.5 mmHg when your hand is relaxed in a neutral position. In people with carpal tunnel syndrome, that pressure climbs to anywhere between 30 and 110 mmHg. When the pressure reaches about 20 mmHg, blood flow through the tiny veins inside the nerve slows and fluid begins to build up. At higher pressures (60 to 80 mmHg), even the small arteries feeding the nerve get choked off. Over time, this starves the nerve of oxygen and nutrients, which is what produces the symptoms.
Who Gets It and Why
Carpal tunnel syndrome is more common in women than men, though studies differ on exactly how much more common. It peaks in people aged 50 to 54, with a second spike in those aged 75 to 84. That age pattern tells you something important: this isn’t just a repetitive strain injury from typing, even though that’s what most people assume. Anything that reduces the space inside the tunnel or increases swelling of the tissues within it can trigger the condition.
Common contributors include pregnancy (fluid retention swells the tissues), thyroid disorders, diabetes, rheumatoid arthritis, and wrist fractures that change the shape of the tunnel. Repetitive hand motions, especially with the wrist bent up or down, can play a role too, but they’re usually one factor among several rather than the sole cause.
What It Feels Like
The hallmark symptom is numbness and tingling in your thumb, index finger, middle finger, and part of your ring finger. Your little finger is not affected, because it’s served by a different nerve entirely. That detail is one of the easiest ways to distinguish carpal tunnel syndrome from other causes of hand numbness.
Most people first notice symptoms at night. You might wake up with your hand feeling “asleep” and need to shake it out to restore sensation. This happens because many people sleep with their wrists bent, which increases pressure in the tunnel. As the condition progresses, the numbness starts creeping into daytime activities: holding a phone, gripping a steering wheel, or buttoning a shirt. In advanced cases, the muscles at the base of your thumb can weaken and visibly shrink, making it harder to grip objects or pinch things between your thumb and fingers.
How It’s Diagnosed
A doctor can often identify carpal tunnel syndrome with two simple physical tests. In the first (Phalen’s test), you press the backs of your hands together with your wrists fully bent and hold for about a minute. If this reproduces your tingling or numbness, it’s a positive result. This test is fairly reliable, with a sensitivity of 85% and a specificity of 89%, meaning it correctly identifies most people who have the condition and rarely flags those who don’t.
The second test involves tapping over the nerve at the wrist to see if it triggers tingling in the fingers. This one is less reliable, correctly identifying only about 67% of cases. When the diagnosis is uncertain, or before surgery is considered, a nerve conduction study can measure how quickly electrical signals travel through the median nerve. Slowed conduction through the wrist confirms compression.
Starting With Conservative Treatment
For mild to moderate symptoms, the first step is usually a wrist splint worn at night. The splint holds your wrist in a neutral position so pressure in the tunnel stays low while you sleep. It should be worn every night for at least eight weeks before you judge whether it’s helping. Importantly, the splint is meant for nighttime only. Wearing it during the day can actually weaken your wrist and hand muscles over time.
Beyond splinting, making changes to how you use your hands during the day matters. When typing, keep your wrists straight rather than bending them up or down. Frequent breaks from repetitive hand tasks help, as does reducing the force you use when gripping tools or pressing keys. These adjustments won’t reverse nerve damage that’s already occurred, but they can slow progression and reduce flare-ups.
Steroid Injections: Short-Term Help
If splinting alone isn’t enough, a steroid injection into the carpal tunnel can reduce swelling and temporarily relieve pressure on the nerve. The relief can be significant, but it tends to be short-lived. A large randomized trial published in The Lancet found that only 16% of patients who started with a steroid injection had recovered after 18 months without eventually needing surgery. About half of the patients in the injection group went on to have surgery within that 18-month window. Injections work best as a bridge, buying time while you explore other options or wait for surgery scheduling.
When Surgery Makes Sense
Carpal tunnel release is one of the most commonly performed hand surgeries. The procedure involves cutting the ligament that forms the roof of the tunnel, which permanently opens up the space and takes pressure off the nerve. The same Lancet trial found that patients who started with surgery had a 16 percentage point higher chance of recovery at 18 months compared to those who started with an injection.
After surgery, your wrist will typically be bandaged or splinted for one to two weeks. You may need occasional splint use for about a month. The full recovery timeline varies widely. If the nerve was only mildly compressed, you might feel better within a few weeks. If the nerve was severely compressed for a long time, recovery can take several months, and some residual numbness or weakness may persist. Grip strength is usually the last thing to fully return.
Surgery is generally recommended when symptoms are severe, when there’s measurable muscle wasting at the base of the thumb, when nerve conduction studies show significant slowing, or when conservative treatments have failed after a reasonable trial period. For people with mild, intermittent symptoms, conservative treatment is a reasonable first approach. For those with constant numbness or weakness, waiting too long can lead to permanent nerve damage that surgery can’t fully reverse.