Carpal tunnel

Causes and
risk factors

Carpal tunnel:
it’s all in the wrist

The carpal tunnel is a passageway in your wrist, where your hand meets your forearm. The flexor tendons that bend your fingers and a major nerve called the median nerve pass through it. The median nerve is what provides your sense of touch and allows you to feel with your thumb, index finger, middle finger, and half of your ring finger.

Carpal tunnel doesn’t usually affect the pinkie because it’s connected to the ulnar nerve. If your pinkie (also called your little finger) is numb, it’s probably a sign of a different condition. The median nerve also connects to the palm muscles at the base of the thumb.

doigts qui se retractent

Are you at risk for developing carpal tunnel syndrome?

How does
carpal tunnel start?

The floor of the carpal tunnel is made up of small wrist bones and the roof is a strong, thick bank of tissue called the transverse carpal ligament, also known as the anterior annular ligament. In some cases, often due to swelling and inflammation of the tendons, pressure on the median nerve inside the tunnel increases.

This increase in pressure affects the flow of blood and oxygen to the nerve’s cells, which in turn affects nerve function and how quickly electric signals can travel through it, causing numbness. At more advanced stages, nerve signals might stop completely, which is known as a nerve conduction block. This can permanently damage nerve fibres and their cells, which are called axons.

When this happens, patients can lose their sense of touch in their thumb, index finger, middle finger, and ring finger, impairing hand function. Their hands lose their dexterity, and the muscles connected to the median nerve can even start to atrophy, or shrink. Without prompt treatment, these effects can be irreversible, which is why patients shouldn’t ignore this condition or delay taking action.

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What causes carpal
tunnel syndrome?

This disease affects not only healthy people but also people with risk factors that predispose them to carpal tunnel syndrome such as:

  • Diabetes: Hand problems are a common complication of diabetes. By some estimates, nearly one in five diabetics (types 1 and 2) will develop CTS in their lifetime. Their cases are also often more severe.
  • Smoking: Smoking, and even exposure to secondhand smoke, are risk or contributing factors for several neuropathies, including CTS. Nicotine may also slow down healing after surgery.
  • Obesity: Extra body weight can increase pressure on the median nerve by causing inflammation and fluid buildup in fascial spaces.
  • Arthritis: Any chronic inflammatory conditions can make pressure on the median nerve worse and lead to carpal tunnel. It is estimated that arthritis patients are twice as likely to develop carpal tunnel syndrome.
  • Occupational factors: Certain repetitive gripping movements, wrist flexion and extension, and the use of vibrating tools may be considered risk factors.
  • Hypothyroidism: Hypothyroidism can make the median nerve bigger, which increases the risk of compression. In fact, these conditions occur at the same time so frequently that CTS is a common sign that the thyroid isn’t working properly.
  • Pregnancy: Swelling, water retention, and hormonal imbalances during pregnancy can contribute to CTS. According to a variety of studies, CTS may affect up to 60% of pregnant people. Symptoms generally start to go away after the baby is born or has stopped nursing.
  • Menopause The hormonal changes associated with menopause or ovary removal can cause the carpal tunnel to shrink, which makes mechanical issues more likely.
  • Injury A sprain or incorrectly healed fracture might cause structural damage and create an environment that makes CTS likelier to develop.

Sometimes, doctors don’t find any underlying risk factors. In such cases, the condition is called idiopathic carpal tunnel syndrome.



What are the main causes of carpal tunnel?

Carpal tunnel syndrome is associated with several personal and occupational risk factors, but genetic predisposition or your job, hobbies, or lifestyle don’t always provide an explanation for why you get it. It’s often impossible to pinpoint the exact cause of CTS.

Can my job cause carpal tunnel?

Certain jobs that require repetitive, non-ergonomic movements can cause someone who is already predisposed to develop symptoms. In some cases, you might need to take time off.

Can CTS be prevented?

A healthy lifestyle, treating any underlying conditions, and ergonomic workstations and processes are the best ways to prevent carpal tunnel.

Practical and comprehensive
medical guide

Everything you need to know to identify and treat Carpal tunnel syndrome. Written in clear and simple language by hand surgeon Dr. Jean-Paul Brutus, this e-guide identifies the causes, symptoms, and different ways to treat CTS and offers recommendations on how to ease your symptoms at home.