Carpal Tunnel Syndrome

Carpal tunnel syndrome happens when the median nerve — the nerve that gives your thumb, index, middle, and half of your ring finger their feeling and fine movement — gets squeezed where it passes through a narrow channel at the base of your palm (the carpal tunnel). It's the most common nerve-pinching condition in the upper limb, affecting roughly 3 to 4 percent of people at some point in life. Women get it two to three times more often than men, and it becomes more common with age.

In most people there's no single cause. Things that make it more likely include carrying extra weight, pregnancy, diabetes, an underactive thyroid, inflammatory arthritis, a previous wrist fracture, and work or hobbies that involve long stretches of gripping or vibration (assembly-line work, knitting for hours, motorcycles, power tools). The classic symptoms are numbness and tingling in the thumb, index, middle, and the thumb-side half of the ring finger — usually worse at night and with repetitive hand use.

The carpal tunnel is a small channel at the base of your palm — the wrist bones make the floor and walls, and a tough band of tissue called the transverse carpal ligament forms the roof. Inside, the median nerve shares that narrow space with nine tendons that bend your fingers. Anything that raises pressure inside the tunnel — swelling of the tendon linings, fluid retention, a cyst, or holding your wrist sharply bent for long stretches — can squeeze the nerve. Mild compression first irritates the nerve's outer insulation; long-standing severe compression damages the nerve fibers themselves. That's why mild cases often improve with non-surgical care, while advanced cases — especially when the muscle at the base of the thumb has visibly shrunk — may not fully recover even after a successful release.

The hallmark of carpal tunnel syndrome is numbness and tingling in your thumb, index finger, middle finger, and the thumb-side half of your ring finger — precisely the territory the median nerve supplies. Most people notice it first at night: you wake up with pins and needles in your hand, and shaking it out overhead (doctors call this the "flick sign") brings quick relief. The reason is positional — your wrist naturally curls inward as you sleep, which kinks the already-tight tunnel and raises the pressure on the nerve.

During the day the same pattern shows up whenever your wrist stays bent for a stretch — gripping a steering wheel, holding a phone to your ear, reading a book in bed. Over time the numbness creeps in more easily and takes longer to clear. You may start fumbling with buttons, dropping small objects, or struggling to pick up a coin from a flat surface — the nerve controls the fine pinch between your thumb and fingertips, and when its signal weakens, those precision tasks are the first to go.

In advanced cases the muscle pad at the base of your thumb (the thenar eminence) visibly flattens and shrinks — a sign that nerve fibers have been damaged, not just irritated. If numbness has become constant or you notice that flat spot forming, those are reasons to move evaluation up rather than wait.

Most of the time the diagnosis is made right in the exam room. Your surgeon will use a few standard moves designed to bring on your symptoms — Phalen's test (holding the wrists fully bent for about a minute), Tinel's sign (light tapping directly over the nerve), and the carpal compression test (gentle steady pressure on the wrist). They'll also check the fine sensation in your fingertips and the strength of the muscles at the base of your thumb to track how severe the compression is over time.

When the diagnosis isn't clear-cut, or when surgery is on the table, your surgeon may order electrodiagnostic studies — a combination of nerve conduction studies (small electrical pulses that measure how quickly the signal travels through the nerve) and EMG (a thin needle in the muscle to see how it's responding). Together these confirm carpal tunnel, grade how severe it is, and rule out other causes like a pinched nerve in the neck (cervical radiculopathy). Ultrasound can also show swelling of the median nerve right where it enters the tunnel and is useful in selected cases.

Non-surgical care is the first step for mild-to-moderate cases — especially when the thumb muscles still look and feel normal. Three things have solid evidence behind them: a wrist splint worn at night, an injection of corticosteroid into the tunnel, and a short course of oral anti-inflammatory pills. The strongest short-term combination is the splint plus the injection.

Carpal tunnel release — surgery to cut the band of tissue that forms the roof of the tunnel and create more space for the nerve — is considered when the case is already severe at the first visit (visible thumb-muscle wasting, constant numbness, or markedly abnormal nerve tests), when a real attempt at non-surgical care hasn't worked, or when symptoms come right back after a corticosteroid injection. Release very reliably relieves the tingling and night symptoms. Recovery of strength and full sensation in advanced cases is less predictable and depends on how healthy the nerve was going in.

Recovery after carpal tunnel release is usually straightforward. Night symptoms and tingling typically improve first, often early in recovery. Dressing changes and suture removal are handled at a brief follow-up, and most patients resume light hand use soon after. A deep ache at the base of the palm — “pillar pain” — is common for a period and gradually resolves. Grip strength returns more slowly and continues to improve as the hand is used normally.

Recovery of sensation and thumb strength tracks the severity of the nerve compression before surgery. Patients with long-standing, advanced disease and visible thenar atrophy may have residual deficits even after successful release. Your OSI provider advances activity based on the hand’s response, not a fixed calendar.

External patient-education references and related OSI pages for additional background:

• Britannica — Carpal tunnel syndrome
• Britannica — Hand (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language