Carpal tunnel syndrome

At a glance

  • The carpal tunnel is a narrow passageway in the wrist. Tendons and the median nerve pass through it.
  • In carpal tunnel syndrome, the tissue inside the carpal tunnel is swollen.
  • If this tissue pushes against the median nerve, it can cause abnormal sensations and pain.
  • Overusing your hands or putting abnormal stress on them increases the risk of carpal tunnel syndrome.
  • Wrist splints and steroid injections can help. Surgery is sometimes an option too.

Introduction

Photo of a worker using a jackhammer
PantherMedia / Dmitry Kalinovsky

Most people's hands briefly "fall asleep" every now and then. The hand then feels numb or tingly. Although this is unpleasant, it's usually over very quickly. Carpal tunnel syndrome has similar symptoms – but they keep coming back again and are often painful.

The carpal tunnel is a passageway inside the wrist that is surrounded by bones and connective tissue. It is located on the inner side of the wrist at the base of the hand, and is covered by a strong, fibrous band made up of connective tissue, called the transverse carpal ligament. Tendons and the median nerve run through the carpal tunnel. This nerve is responsible for sensation and movement in the ball of the thumb and some parts of the hand. If the tissue inside the carpal tunnel swells up, it can push against the median nerve, which is what causes carpal tunnel syndrome. The symptoms often go away on their own, but they can sometimes last for quite a long time. Various treatments can provide relief.

Illustration: The carpal tunnel and the nerves in the hand

The carpal tunnel and the nerves in the hand

Symptoms

Symptoms arise if the tissue in the carpal tunnel becomes swollen, putting pressure on the median nerve.

Carpal tunnel syndrome can cause the following symptoms:

  • Abnormal sensations: Parts of the hand feel numb or may tingle (also called "pins and needles"). Usually, the thumb and the middle three fingers are affected (these appear red in the illustration). Your hand falling asleep at night could be a typical early sign of carpal tunnel syndrome.
  • Pain in your fingers: Sometimes the entire hand might also hurt, or the pain may radiate into your arm.

These symptoms are most common at night and in the morning. They usually affect both hands, but not necessarily at the same time. Shaking your hands often improves the symptoms.

Causes

It's often difficult to tell exactly what caused the tissue to swell. Overusing the hand and wrist sometimes plays a role. This may happen if you, for instance, put too much pressure on your wrist, or overstretch or bend it too far. Repetitive activities like using a jackhammer, which makes the wrist vibrate a lot, can also cause the tissue to swell.

The symptoms of carpal tunnel syndrome often get worse when the wrist is exposed to this kind of physical strain. It's not clear whether they can also cause the condition, though. It's commonly believed that working at a computer can increase your risk of carpal tunnel syndrome, but research suggests that any effect is minor.

Some conditions can make you more likely to develop carpal tunnel syndrome. These include rheumatism, diabetes, wrist injuries and repeated tendon sheath inflammations. Pregnant women are at greater risk because more fluid builds up in their body’s tissue.

The symptoms may suddenly become very severe, but this only rarely happens. Known as “acute carpal tunnel syndrome,” it is usually caused by an inflammation, injury or bleeding in the wrist.

Prevalence

Carpal tunnel syndrome is most common in people between the ages of 40 and 70 years. It is very rare in children. Women are more likely to be affected. People who do lots of physical labor are also more likely to have it. Every year, about 3 out of 1,000 people develop carpal tunnel syndrome.

Outlook

Some people may have only mild symptoms which come and go over many years. It is estimated that, left untreated, the symptoms go away within six months in about 1 out of 3 people. In others, the symptoms don't go away. If the condition worsens, the hand may feel numb all the time. In later stages, carpal tunnel syndrome can cause the muscles on the ball of the thumb to waste away (atrophy). If your hand becomes weaker and you can't feel it properly, it can be difficult to do everyday things like hold a teacup.

Diagnosis

Your doctor will first ask you about your symptoms and then examine your hand and wrist. There are specific tests to see how well the hand and fingers can move and feel things.

Electrophysiological tests like electroneurography (ENG) may also be needed to find out whether carpal tunnel syndrome is in fact causing the symptoms. This test can measure how effectively the electrical signals are being carried by the nerves, and how well the nerves are working. The results are considered together with the described symptoms, the physical exam, your life circumstances and medical history.

It's also important to rule out other possible medical causes. For example, changes in the cervical spine (the bones in your neck) may irritate the nerve roots, causing similar symptoms. Other nervous system diseases such as polyneuropathy can also have this effect.

Treatment

Mild to moderate carpal tunnel syndrome can usually be treated with a splint at first. The splint is worn at night to prevent the wrist from bending. Doctors may also advise you to avoid activities thought to be related to this condition.

Injecting steroids into the carpal tunnel can temporarily relieve the symptoms. They aren't effective in the long term, though.

If the carpal tunnel syndrome doesn't go away, surgery may be considered. This involves cutting the flexor retinaculum that arches across the base of the hand The aim is to reduce pressure on the median nerve. This procedure can make the symptoms go away for good, but it's not always necessary. Other treatments are usually tried out first, especially if the condition is still in an early stage. Urgent surgery is usually only needed for treating a rare condition called acute carpal tunnel syndrome.

Some early research results suggest that extracorporeal shock wave therapy (ESWT) can relieve the symptoms somewhat. In shock wave therapy, a device is used to send high-pressure sound waves through the skin. In Germany, the costs of this treatment are usually not covered by statutory health insurers.

Other treatments such as , ultrasound therapy, laser therapy or magnetic field therapy may also be recommended. But there is no that they are effective in the treatment of carpal tunnel syndrome.

Many people take painkillers to relieve their symptoms – particularly non-steroidal (NSAIDs), which are available over the counter at pharmacies and drugstores. Taking vitamin B6 products is sometimes recommended too. They are claimed to strengthen the nerves. So far, though, research suggests that neither NSAIDs nor vitamin B6 can provide enough pain relief.

Further Information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.

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Deutsche Gesellschaft für Handchirurgie (DGH), Deutsche Gesellschaft für Neurochirurgie (DGNC). S3-Leitlinie: Diagnostik und Therapie des Karpaltunnelsyndroms. AWMF-Registernr.: 005-003. June 2012.

Huisstede BM, Hoogvliet P, Franke TP et al. Carpal Tunnel Syndrome: Effectiveness of Physical Therapy and Electrophysical Modalities. An Updated Systematic Review of Randomized Controlled Trials. Arch Phys Med Rehabil 2018; 99(8): 1623-1634.

Huisstede BM, Randsdorp MS, van den Brink J et al. Effectiveness of Oral Pain Medication and Corticosteroid Injections for Carpal Tunnel Syndrome: A Systematic Review. Arch Phys Med Rehabil 2018; 99(8): 1609-1622.

Kim JC, Jung SH, Lee SU et al. Effect of extracorporeal shockwave therapy on carpal tunnel syndrome: A systematic review and meta-analysis of randomized controlled trials. Medicine (Baltimore) 2019; 98(33): e16870.

Kozak A, Schedlbauer G, Wirth T, Euler U, Westermann C, Nienhaus A. Association between work-related biomechanical risk factors and the occurrence of carpal tunnel syndrome: an overview of systematic reviews and a meta-analysis of current research. BMC Musculoskelet Disord 2015; 16: 231.

Mediouni Z, de Roquemaurel A, Dumontier C, Becour B, Garrabe H, Roquelaure Y et al. Is carpal tunnel syndrome related to computer exposure at work? A review and meta-analysis. J Occup Environ Med 2014; 56(2): 204-208.

Middleton SD, Anakwe RE. Carpal tunnel syndrome. BMJ 2014; 349: g6437.

Shiri R, Falah-Hassani K. Computer use and carpal tunnel syndrome: A meta-analysis. J Neurol Sci 2015; 349(1-2): 15-19.

Xie Y, Zhang C, Liang B et al. Effects of shock wave therapy in patients with carpal tunnel syndrome: a systematic review and meta-analysis. Disabil Rehabil 2020 [Epub ahead of print]: 1-12.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Updated on May 20, 2021
Next planned update: 2024

Authors/Publishers:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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