Carpal Tunnel Syndrome (CTS)
Written by Ada’s Medical Knowledge Team
What is carpal tunnel syndrome (CTS)?
Carpal tunnel syndrome (CTS) is a painful medical condition in which the median nerve in the wrist becomes compressed inside the carpal tunnel. 1
- The median nerve is a nerve which passes through the arm to the hand, on each side of the body and which controls sensation and movement in the hand.
- The carpal tunnel is a narrow passageway in the wrist on the palm side of the hand, made up of bones and ligaments. The median nerve is the only nerve in the body which passes through the carpal tunnel.
When direct pressure is exerted on a nerve, as in CTS, this is, in medical terms, referred to as an entrapment neuropathy. CTS is the most common type of entrapment neuropathy. 2 When the nerve becomes entrapped, this causes symptoms including pain, tingling, numbness and hot-and-cold sensations. The hand may become difficult to move. The symptoms of CTS are often worst at night and absent during the day.
In most cases, the exact cause of CTS is unknown, but it usually develops in adulthood and is often attributed to work-related activities such as typing and other repetitive movements, such as mopping, sweeping or using vibrating tools. The risk of CTS is increased in people experiencing arthritis, thyroid conditions and pregnancy.
Around 60 percent of people affected by CTS experience the condition in both wrists (bilateral CTS). CTS which only affects one wrist is called unilateral CTS. In both bilateral and unilateral CTS, the dominant hand is usually first and/or more strongly, affected. 3
CTS caused by pregnancy often goes away on its own when the pregnancy concludes. Likewise, CTS that is caused by a medical condition usually goes away on its own when the condition is managed effectively.
To treat CTS, some people may find it helpful to wear a wrist splint at night to hold the wrist in a still position and use OTC or prescription medications to manage the pain and inflammation of CTS. For others, surgery may be necessary to alleviate the condition.
The symptoms of CTS are usually worse at night and may be absent during the day. They can be intensified or brought on by forceful activities involving the wrist, especially the use of vibrating tools and heavy lifting. The most common symptoms of carpal tunnel syndrome are: 4
- Numbness and tingling in the thumb, index finger, middle finger and the radial half of the ring finger (the half of the ring finger closest to the palm, which is supplied by the median nerve). This can result in atrophy of the affected muscles (which may appear flattened).
- Burning pain in the wrist
- Loss of grip strength and dexterity
Proximal radiation (the sensation that the pain has radiated to nearby areas) is a less common, but not unusual, symptom of CTS. People may experience pain related to CTS in other parts of the arm, namely:
- The volar forearm; the side of the forearm that is on the same side as the palm of the hand
- The medial arm; the skin on the side of the arm where the medial brachial cutaneous nerve is
- The shoulder
The symptoms of CTS worsen the longer the condition is left untreated. If a person is affected by CTS for several months, they may begin to feel numbness in the hand on a permanent basis and lose the ability to feel hot and cold sensations with the hand.
Seek medical attention promptly if any of the symptoms of CTS are present, in order to diagnose and begin treating the condition at an early stage.
Acute carpal tunnel syndrome (CTS)
Acute carpal tunnel syndrome is a version of CTS in which the median nerve is severely crushed, usually as the result of an injury or chronic health condition. Unlike regular CTS, acute CTS requires urgent surgical intervention to prevent serious health consequences, such as the permanent loss of sensation or movement in the affected area. 5
Factors which are associated with the development of acute CTS include: 5
- Fractures and fracture dislocations around the wrist
- Vascular disorders (diseases affecting the blood vessels)
- Hemorrhagic conditions (conditions relating to abnormal blood flow or clotting)
- Rheumatologic disorders (conditions relating to pain and stiffness in the body, such as arthritis and Crohn’s disease)
- Anomalous anatomy (atypical wrist or nerve structure)
Causes of CTS
Carpal tunnel syndrome is caused by the median nerve (the nerve which controls sensation and movement in the hands) becoming compressed. Any medical conditions and/or injuries which cause swelling in the wrist can reduce the amount of space inside the carpal tunnel, causing pressure to be exerted on the median nerve and activating the symptoms of CTS.
The biological cause of CTS within the carpal tunnel is the swelling of a protective lining of tendons called the tenosynovium. This sets off a chain of related changes within the carpal tunnel: 6
- The swelling of the tendons is understood to cause a buildup of synovial fluid; the fluid which normally protects and lubricates the tendons; within the carpal tunnel.
- In reaction to this buildup of fluid, a band across the top of the carpal tunnel called the transverse ligament becomes thicker and broader.
- The swelling and the enlarged transverse ligament exert pressure on the median nerve, depriving it of the blood supply and oxygen it needs in order to function normally. This causes the median nerve to become damaged and the symptoms of CTS to develop.
The medical or circumstantial basis for these developments occurring in the carpal tunnel is unknown in many cases, and there is no test available to identify a specific cause. However, the development of CTS may be caused by factors including: 1
In particular, CTS may be attributed to activities which involve repetitive movements, heavy lifting and using vibrating tools. Professional activities which are particularly associated with CTS include assembly work, farming, sewing, cleaning, and meat packing.
People born with smaller bone structures are more likely to have wrist and bone structures in which the median nerve is susceptible to the compression that causes CTS. A genetic predisposition to any of the many medical conditions which are linked to CTS may be described as the indirect cause of CTS in a person who develops CTS as a result of another medical condition. 7
Musculoskeletal disorders (conditions affecting the muscles and/or skeleton) and autoimmune diseases may trigger the development of CTS by causing inflammation in the hands and wrists. The main medical conditions which are linked to CTS are diseases of the thyroid gland, rheumatoid arthritis, chronic kidney insufficiency, Down syndrome, osteoarthritis and obesity. If CTS is caused by a medical condition, it may be alleviated by effectively treating the causal condition. 6 Feeling unwell? Get a free symptom assessment by downloading the Ada app.
Pregnant women sometimes develop CTS due to hormonal changes and fluid retention. If CTS is caused by pregnancy alone, it will often go away when the pregnancy ends. Rest, ice, elevation and exercise may all help to alleviate the symptoms of CTS during pregnancy. 8
The use of some medications has been linked to CTS, but more research is needed to understand the mechanisms by which these may cause CTS to develop. Medications which have been linked to CTS include: 6
- Medications which affect the immune system (such as interleukin-2)
- Medications which prevent blood clotting (such as warfarin)
Certain risk factors increase a person’s likelihood of developing CTS. These include occupational factors such as working in a role that necessitates intensive and/or repetitive use of one’s hands, and non-occupational factors, such as medical conditions like diabetes and hypothyroidism which may cause CTS.
Risk factors for CTS include: 2
CTS is a common complication of pregnancy, due to fluid retention, edema and hormonal changes within the body. One’s likelihood of developing CTS in pregnancy, and the severity of the condition, increases with age. Most people who develop CTS during pregnancy find that it alleviates on its own when the pregnancy concludes.
According to the National Institute of Neurological Disorders and Stroke, women are three times more likely than men to develop CTS. 1
The hormonal changes that accompany menopause can cause a buildup of fluid in the body, increasing the risk of developing CTS. Women, whose hormone levels alter excessively during pregnancy, are more likely to develop CTS in later life, after undergoing menopause, than those whose hormonal changes during pregnancy are within the normal range. 9
CTS is a common complication of arthritis, due to the swelling of joints and tendons associated with the condition. 10
Being middle-aged or elderly
The likelihood of developing CTS increases with age, particularly after 70. In part, this is due to the fact that most musculoskeletal disorders predominantly affect older people, and CTS is a common consequence of these conditions. 11
Between 15 and 20 percent of people with diabetes will develop CTS, which is believed to be due to having high blood sugar levels. Diabetes is often linked to the development of problems with the nerves, such as diabetic neuropathy. In people with diabetes, when blood sugar levels are high, glucose is believed to attach to the tendons. This causes compression within the carpal tunnel as the tendons enlarge, resulting in CTS. 12
Diseases of the thyroid
People with improperly-managed thyroid conditions may retain excess fluid in their connective tissues. This contributes to inflammation within the wrist, which can cause CTS, especially if left untreated. Hypothyroidism (an underactive thyroid) is particularly linked to CTS, but people with hyperthyroidism (an overactive thyroid) are also more likely to develop CTS than the general population. 13
People with a sibling or parent with CTS are more likely to be affected than those without. A person’s bone structure and overall size is largely determined by their genetic makeup, and those with smaller frames have less space in their carpal tunnels, which significantly increases the likelihood of the median nerve becoming trapped and their developing CTS. 7
Using tobacco products
A link has been found between the use of tobacco and developing CTS. Tobacco products negatively affects the body’s immune system and increases a person’s risk of developing inflammatory diseases which can cause a buildup of fluid in the carpal tunnel, which may result in CTS. 14
Injuries to the wrist
It is possible for the median nerve to become compressed due to changes in the structure of the bones and muscles in the wrist that result from injuries. People who play a lot of sports are particularly at risk of hand and wrist injuries that can result in CTS. In injury-related CTS, ensuring that the injury heals properly and that the median nerve ceases to be entrapped will alleviate the condition. 15
Working intensely with one’s hands
CTS is often linked to activities involving repetitive hand and wrist movements, in particular, the use of vibrating tools.
To diagnose CTS, a doctor will usually perform a physical exam on the hand(s) and wrist(s) and ask about the symptoms a person has been experiencing. The purpose of the physical exam is to find out whether a person is experiencing physical sensations that typically relate to the median nerve being compressed.
If these sensations are not present, this can rule out a diagnosis of CTS and the possibility that a person is affected by another condition can be investigated. During the physical exam, doctors look out for:
- Weak muscles surrounding the thumb (which can happen in cases of CTS due to underusing these muscles in order to avoid the pain that often accompanies movement)
- Tinel’s sign which involves tingling and numbness in the fingers when the wrist is tapped at the palm side of the hand (this alone is insufficient for a CTS diagnosis, as it is also a possible symptom of many other conditions)
- A positive Phalen’s maneuver which invilves pain, numbness or tingling in the wrist and fingers when the wrist is flexed to the hand’s maximum ability
Further testing is usually needed, even if all of these symptoms are present, in order to confirm a diagnosis of CTS. This may involve:
Nerve conduction test
Damaged nerves cannot transmit signals to the body parts in order to bring about certain actions as quickly as healthy nerves can. Nerve damage is a common result of CTS. To detect it, the doctor will attach electrodes to the hand and wrist to stimulate the nerves in the fingers and wrist with an electric current.
The speed with which the signal can travel through the nerves will be indicative of the extent of any nerve damage, and can support or discredit a diagnosis of CTS. This test usually takes around 10 minutes to perform, and can be moderately uncomfortable because it produces an unfamiliar tapping/tingling sensation.
Doctors may perform an ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) scan in order to visualize the median nerve and carpal tunnel and determine their exact positions and the extent of the nerve entrapment.
To rule out other conditions which also have symptoms of pain, numbness and tingling in the hand/wrist, including diabetes, diseases of the thyroid and arthritis, doctors may perform a blood test.
Other conditions which may be misdiagnosed as CTS
Carpal tunnel syndrome is frequently misdiagnosed due to the fact that it shares symptoms with several other conditions, including arthritis, wrist tendonitis, repetitive strain injury (RSI) and thoracic outlet syndrome. Symptoms which CTS shares with other conditions include:
- Hot-and-cold sensations
- Difficulty grasping or using one’s hand
It is important to be aware of the key differences between CTS and some other conditions which share its symptoms, in order to avoid a misdiagnosis. Other conditions which are commonly misdiagnosed as CTS include:
Arthritis can affect all the fingers in the hand, whereas CTS cannot affect the little (pinky) finger. Whereas CTS is worse at night, arthritis is not affected by the time of day. The symptoms of CTS can be absent and then suddenly become triggered by a particular activity, whereas the pain associated with arthritis is usually constantly present but alters in intensity during activities which put strain on the hands and wrists. 16
Nerve compression due to conditions affecting the spine
Conditions such as spinal disc herniation (a slipped disc) and cervical stenosis (a condition characterised by weakness and numbness that may affect areas including the spine, neck, shoulders, hands, arms and legs) can cause nerve compression that may result in similar sensations to those of CTS.
In wrist tendonitis, the area affected by symptoms may be different to that of CTS. The pain, numbness and tingling may affect the tendons in any part of the hand or wrist, whereas in CTS the symptoms are limited to the thumb, index and middle fingers, the palm side of the wrist and the radial half of the ring finger.
Thoracic outlet syndrome
In thoracic outlet syndrome, blood vessels or nerves in the space between the collarbone and the first rib become compressed. The pain can affect the shoulders and neck, as well as the fingers. The fingers which are usually affected are the little (pinky) finger and the non-radial half of the ring finger. These are the two areas that cannot be affected by the symptoms of CTS. 17
Repetitive strain injury (RSI)
This is a general term to describe symptoms including pain, throbbing and stiffness in the muscles and tendons as a result of overuse and repetitive movements. 18
Repetitive strain injury can occur anywhere in the body, but most often affects the neck, shoulders, forearms, elbows, hands and wrists. When it occurs in the hand and wrists, RSI may be mistaken for CTS, but unlike CTS, RSI is capable of affecting any part of the overall area.
Treatment of Carpal Tunnel Syndrome
Carpal tunnel syndrome may disappear on its own without treatment. If CTS is caused by another condition such as arthritis or an underactive thyroid, its symptoms may alleviate on their own when the causal condition is treated.
If one’s carpal tunnel syndrome is not caused by another treatable medical condition, it is best to begin treatment as soon as possible to prevent the symptoms worsening and to reduce the level of damage to the median nerve associated with continuous pressure.
For those with mild symptoms, and/or who have been affected for a short time, non-surgical treatments such as wrist splinting and medications may be sufficient. In more severe cases, or where the symptoms of carpal tunnel syndrome cannot be alleviated by non-surgical means, surgery to relieve pressure on the median nerve may be recommended.
In pregnant women, the symptoms of carpal tunnel syndrome often abate in the weeks after the pregnancy ends, with no need for treatment. Those who are still experiencing symptoms of CTS three months after the conclusion of the pregnancy should seek medical attention to devise a treatment plan. 19
Wrist splinting is a common first-line treatment for mild to moderate CTS. It involves wearing a splint at night for a few weeks in order to hold the joint in a neutral position. This helps to prevent the symptoms of CTS from developing overnight, when the pain is usually worse.
Wrist splints come in many different shapes and sizes and a doctor can recommend a suitable one. A wrist splint works by preventing the hand from bending in way which brings on the symptoms of CTS during the night. However, because the wrist is kept in a fixed position by the splint, it is important to exercise the hand and wrist during the day to prevent the muscles from weakening due to underuse.
The effects of wrist splinting usually become noticeable after a few weeks of wearing the splint. In some cases, this is a sufficient treatment for CTS and symptoms will disappear.
However, for many people, splinting is a temporary solution rather than an effective treatment for CTS, and symptoms may return. In this case, other treatment options such as medications or surgery may be recommended. 20
Medications for CTS
Medications that are prescribed in the management of CTS can provide temporary relief from the pain and inflammation associated with the condition. The medications most commonly prescribed for CTS are nonsteroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen and, in more severe cases of CTS, corticosteroids, which are taken as tablets or injected into the carpal tunnel.
NSAIDs are available as over-the-counter or prescription medication, and can temporarily minimize joint and muscle pain. Naproxen and ibuprofen are the NSAIDs most commonly used for pain management in CTS. Long-term use of NSAIDs carries multiple health risks, including impaired gastroenteric function and increased likelihood of peptic ulcer disease. NSAIDs should be taken for a limited period of time only, in consultation with a medical professional.
Corticosteroids can be taken orally as tablets or injected into the carpal tunnel. Local injections are considered to be more effective than oral corticosteroids at reducing the pain and inflammation associated with CTS. Corticosteroids may be prescribed in cases of severe CTS, and/or when wrist splinting has not provided long-term relief. 21
Short-term use of corticosteroids (for example, for a few weeks or a month) is associated with a variety of side effects, including stomach problems, skin problems and weight gain, which may render them an unsuitable treatment option for some people.
Continuous (longer-term) use of corticosteroids is never recommended for the treatment of CTS as it is associated with increased risk of the development or worsening of a variety of health conditions such as diabetes and osteoporosis.
Medications help manage the painful symptoms of CTS, rather than treating the cause. Neither NSAIDs nor corticosteroids can relieve the pressure on the median nerve and these medications can therefore only provide temporary relief from the symptoms of CTS. Medications should be used as part of a wider treatment strategy which focuses on releasing the entrapped median nerve.
Surgery for CTS will not usually be considered as a first-line treatment, and is usually recommended only when CTS is at a late stage and/or has not been alleviated by non-surgical treatments. Urgent surgery for CTS is usually only needed as a treatment for acute CTS.
Surgery for CTS involves cutting a part of the carpal tunnel in order to reduce pressure on the median nerve. The part of the carpal tunnel which is cut during surgery is known as the flexor retinaculum. There are two possible surgical procedures for CTS: endoscopic carpal tunnel release and open carpal tunnel release. 22
Both types of surgery can be performed as an outpatient procedure and usually only require a local anesthetic to numb the hand or arm.
Endoscopic carpal tunnel release involves making a small incision in the palm and/or the wrist, and a small camera called an endoscope is inserted into one of the incisions to monitor the procedure. The flexor retinaculum is then cut with an instrument inserted into the second incision. It is also possible to perform the procedure by making only one incision in the wrist, and inserting both the surgical instrument and the endoscope into the same incision.
Open carpal tunnel release involves cuting the inside of the wrist to reveal the carpal tunnel. The surgeon will then cut through the flexor retinaculum.
The recovery time may be slightly shorter for an endoscopic procedure, but most people can return to work less than three weeks after either procedure. 23
Self-care for managing CTS
If a person is diagnosed with CTS, they can help to prevent the condition getting worse by making certain adaptations to their lifestyle. The two principal lifestyle changes which are recommended for people who have been diagnosed with CTS are:
Exercising the hands and wrists
There are many possible hand exercises that can be incorporated into a person’s daily routine in order to ease the pain associated with CTS and prevent future injuries. 24 When a person is diagnosed with CTS, doctors will be able to recommend and demonstrate exercises, and provide guidelines on how often these should be carried out.
CTS can be aggravated by overuse of the hands and wrists, in particular through repetitive activities such as working in an assembly line or using vibrating tools. People with CTS whose work involves activities that may increase their symptoms are often advised to stay home when they are undergoing treatment to ensure its effectiveness. Wearing a wrist splint at night can help to reduce strain. 20
It is not always possible to prevent CTS, particularly if it is caused by pregnancy or another health condition. However, there are some lifestyle changes that people can make to reduce the likelihood of developing CTS. These preventative measures are particularly recommended for people whose daily activities are associated with a higher risk of CTS.
Preventative measures against developing CTS include:
- Ensuring that any other health conditions a person may have that could contribute to developing CTS (such as diabetes are treated or managed effectively
- Maintaining a healthy weight, diet and exercise regime
- Avoiding the use of tobacco products, which weaken the immune system and increases the likelihood of developing inflammatory conditions that can cause CTS
- Regularly assessing one’s day-to-day routine in order to minimize activities involving repetitive or intense movements that might contribute to an increased risk of CTS
- Following ergonomic guidelines (recommendations on how to position and use equipment for efficiency and comfort) at home and at work, in order to ensure that all activities are carried out in the most comfortable, appropriate way for the body
- Taking regular breaks from any activities that contribute to CTS, especially when using vibrating tools, in order to reduce the impact of activities which put pressure on the wrists and hands
Carpal tunnel syndrome FAQs
Q: Does typing cause CTS?
A: Typing is associated with an increased likelihood of developing repetitive strain injury (RSI). If RSI affects the tendons or ligaments in the carpal tunnel, this can cause compression on the median nerve and the development of CTS. However, research has shown that there is at most a very small direct link between computer work and CTS. Activities which involve using the hands and wrists with a greater intensity, such as using vibrating tools, are significantly more likely to cause CTS than typing. The use of ergonomic computer keyboards is, however, sometimes recommended as a preventative measure against developing CTS. 20
Q: Can children be affected by CTS?
A: CTS in children is rare. When it develops, it is most commonly related to having a genetically inherited condition associated with inflammation, such as lysosomal storage disease, which can cause swelling in the joints and pressure to build up in the carpal tunnel. The symptoms of CTS and its treatment options are the same for children as for adults. 25 If you are concerned that your child, or a child that you know, may be affected by CTS, you can get a free symptom assessment by downloading the Ada app.