Carpal tunnel syndrome is the most common nerve compression we see, and the most common cause of numbness and tingling in the hand. It is also one of the more satisfying problems in neurology: the diagnosis is usually clear, the testing is straightforward, and most people get better without surgery.
What is carpal tunnel syndrome?
The carpal tunnel is a narrow passage on the palm side of the wrist, bounded by bone and a thick ligament. It carries the finger tendons and the median nerve. Anything that swells the tendons or narrows the space presses on the nerve. Median nerve compression at the wrist is the textbook name for the result.
That nerve supplies feeling to the thumb, index, middle, and half of the ring finger, and powers the muscles at the base of the thumb. The symptoms fall exactly there, which is what makes the pattern so recognizable. The little finger is spared, because a different nerve supplies it.
Visual guide
The median nerve at the wrist
- Location: The median nerve passes through a narrow space at the wrist.
- Sensation: Tingling often affects the thumb, index, and middle fingers.
- Pattern: Symptoms are commonly worse at night.
Carpal tunnel symptoms
- Numbness, tingling, or burning in the thumb, index, middle, and half the ring finger
- Symptoms that wake you at night, or appear while driving or holding a phone
- Aching in the hand, wrist, or forearm, sometimes reaching the shoulder
- A feeling that the fingers are swollen when they are not
- Later: weakness gripping or pinching, and dropping things
Forearm pain is common, because an irritated nerve sends pain up its own length as well as down it. Forearm pain on its own, with no numbness in the fingers, is usually not carpal tunnel syndrome and more often a tendon or neck problem.
How it progresses
Early carpal tunnel syndrome is intermittent: numbness at night or after a long drive that shaking the hand clears. Next it appears during the day with ordinary tasks. Later the numbness becomes constant, grip weakens, and the muscle at the base of the thumb thins. Nerve conduction studies grade the compression as mild, moderate, or severe, which is what most people mean by the stages of carpal tunnel.
Signs the nerve is being damaged
Numbness that is constant rather than coming and going, visible thinning of the muscle at the base of the thumb, or dropping objects means the nerve is already losing fibers. That moves things from "try a splint" to "get tested now", because recovery is less complete once muscle is lost.
Causes and risk factors
| Factor | Why it matters |
|---|---|
| Repetitive gripping, wrist flexing, or vibration | Swells the tendons that share the tunnel |
| Diabetes, thyroid disease, rheumatoid arthritis, kidney disease | Make the nerve more vulnerable and the tunnel tighter |
| Pregnancy | Fluid retention raises pressure in the tunnel; usually resolves after delivery |
| Prior wrist fracture or arthritis | Narrows the tunnel structurally |
| A naturally narrow tunnel | Partly inherited, which is why it often runs in families |
New carpal tunnel syndrome in both hands is worth a second look. It is sometimes the first sign of thyroid disease, diabetes, or an inflammatory arthritis.
Anatomy at a glanceThe wrist and hand
Inside the carpal tunnel
A nerve and finger tendons share a narrow passage at the wrist.
Ligament roof
A strong band of tissue forms the roof. Wrist bones form the floor and sides of the tunnel.
Median nerve
Pressure on this nerve can cause tingling, numbness, or weakness in the hand.
Flexor tendons
Nine tendons pass through the tunnel alongside the nerve. They help bend the fingers and thumb.
Pressure at the wrist can cause symptoms in the hand.
Simplified cross-section at the wrist. Selected structures are shown to explain the space around the median nerve.
How carpal tunnel is diagnosed
Most of the diagnosis is the history and the examination: which fingers, when, and whether the thumb muscles are weak or wasted. Two bedside tests help. Tapping over the nerve at the wrist may send tingling into the fingers, and holding the wrists bent for a minute may reproduce the symptoms.
Nerve conduction studies measure how well the median nerve carries a signal across the wrist and grade the compression as mild, moderate, or severe. They are worth doing when the diagnosis is uncertain, when surgery is being considered, or when more than one problem may be present.
Carpal tunnel or something else?
The other half of the job is making sure the wrist is actually the source. The nearest look-alike is the ulnar nerve at the elbow, sometimes called cubital tunnel syndrome.
| If the numbness is | The likely source is | Clue |
|---|---|---|
| Thumb, index, middle fingers; worse at night | Carpal tunnel (median nerve at the wrist) | Little finger spared; shaking the hand helps |
| The little and ring fingers | Ulnar nerve at the elbow (cubital tunnel) | Worse when the elbow is bent or leaned on |
A stripe of numbness from the neck into the arm, or numbness in both hands and both feet, has other sources. Our hand numbness page maps every pattern finger by finger, including the pinched nerve in the neck and peripheral neuropathy that are most often confused with carpal tunnel. More than one can be true at the same time.
Treatment
Almost everyone starts conservatively, and for most people that is enough.
- A night splint keeps the wrist straight while you sleep, which is when pressure in the tunnel peaks. Worn nightly over several weeks, it relieves many mild and moderate cases on its own.
- Activity changes to the specific tasks and positions that provoke it, including keyboard and phone habits.
- Hand therapy, including nerve-gliding and tendon-gliding exercises taught by a therapist. Exercises on their own rarely settle carpal tunnel syndrome. Combined with a splint they do better than a splint alone, and they are the part of treatment people can keep doing.
- A corticosteroid injection into the tunnel reduces swelling around the nerve and can give months of relief. A good response also helps confirm the diagnosis.
If those fail, or if testing shows severe compression or the thumb muscle is thinning, carpal tunnel release surgery is the definitive fix. The surgeon divides the ligament forming the roof of the tunnel. It is a short outpatient procedure that relieves symptoms in most people, and we refer to a hand surgeon when it is the right step.
Visual guide
Supporting the wrist
- Splint: A night splint can keep the wrist in a neutral position.
- Activity: Adjustments may reduce pressure that aggravates symptoms.
- Severity: Persistent numbness or weakness can change treatment choices.
When to see a neurologist
People often ask whether carpal tunnel is a neurologist's problem or an orthopedic one. Both treat it. A neurologist's part is localization: confirming the wrist is the problem, and not the neck or the nerves generally, before anyone injects or operates. A hand surgeon's part is the release when it is needed. See a neurologist if the numbness has lasted more than a few weeks, wakes you at night, comes with weakness, or does not stay in the fingers the median nerve supplies.
Dr. Achillefs Ntranos, MD sees carpal tunnel patients in Beverly Hills and Los Angeles. A first visit is 60 minutes and is mostly history and examination. We do not perform nerve conduction studies in our office; when they are needed we arrange them nearby and review the results with you. No referral is needed, and you can request a visit in Beverly Hills or Los Angeles, or by video anywhere in California.
Frequently asked questions
References
- National Institute of Neurological Disorders and Stroke. Carpal tunnel syndrome.
- American Academy of Orthopaedic Surgeons, OrthoInfo. Carpal tunnel syndrome.
- American Academy of Orthopaedic Surgeons, OrthoInfo. Carpal tunnel syndrome therapeutic exercise program.
- Mayo Clinic. Carpal tunnel exercises: can they relieve symptoms?
- Cleveland Clinic. Carpal tunnel syndrome: symptoms, causes and treatment.