Carpal tunnel syndrome - Causes 

Causes of carpal tunnel syndrome 

The symptoms of carpal tunnel syndrome (CTS) are caused by compression (squashing) of the median nerve at the wrist.

The median nerve is responsible for two main functions:

  • relaying physical sensations – such as your sense of touch from your hand to your brain
  • relaying nerve signals – from your brain to your hand, controlling movement

Any pressure on the median nerve can disrupt the nerve signals, affecting your sense of touch and hand movements. The median nerve can become compressed if the tissues inside the tunnel become swollen or the tunnel narrows over time.

Increased risk

In most cases, it is not known what causes the median nerve to become compressed, although a number of things increase the risk of developing CTS. These include:

  • family history
  • certain health conditions, such as diabetes, an underactive thyroid gland or rheumatoid arthritis
  • pregnancy
  • certain injuries to the wrist
  • certain activities

These risk factors are outlined below.

Family history

Research has shown that there is a genetic link to CTS. This means you may have an increased risk of developing CTS if other members of your family have the condition or have had it in the past.

About one in four people with CTS have a close relative, such as a parent, brother or sister, who also has the condition. It is not fully understood how and why the condition is passed on through families.

Health conditions

Certain health conditions appear to increase your risk of developing CTS. These include:

  • diabetes – a chronic (long-term) condition caused by having too much sugar (glucose) in the blood
  • any kind of arthritis – a condition where the joints become painful and inflamed as a result of the immune system attacking the body
  • hypothyroidism – an underactive thyroid gland
  • obesity in young people
  • some drugs used to treat breast cancer, such as exemestane

Less commonly, CTS develops when a person has an abnormal wrist structure, such as an unusually narrow carpal tunnel, or as a result of cysts, growths or swellings in the tendons or blood vessels that pass through the carpal tunnel.

Pregnancy

It is not clear exactly why, but CTS is common during pregnancy. However, many cases resolve after the baby is born. It is not known whether women who have carpal tunnel syndrome during pregnancy are at greater risk of developing the condition in later life.

CTS is also common in women around the time of the menopause.

Injuries

CTS can sometimes occur following a hand injury. Injuries such as sprainsfractures and crush injuries can cause swelling, placing pressure on the median nerve.

These types of injuries can also change the natural shape of the bones and ligaments in the hand, leading to increased pressure on the median nerve.

Certain activities

Certain activities may trigger the development of carpal tunnel syndrome. These tend to involve strenuous grip, repetitive wrist flexion (bending) and exposure to vibration. Examples include:

  • playing a musical instrument
  • assembly packing
  • work that involves manual labour 
  • work with vibrating tools, such as chainsaws

However, further research into the link between work-related hand use and CTS is required to determine whether these types of activities are a definite cause of the condition.

Although much attention is paid to typing as a possible cause of carpal tunnel syndrome, the condition is in fact less common in individuals who type all day than those who carry out more strenuous activities.


Page last reviewed: 18/09/2014

Next review due: 18/09/2016

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The 5 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Boogangles said on 29 May 2014

I have just started to have the symptoms of CTS there is a family history, my mother, my sister, and my niece recently had a operation, I do get cramps in my hands when operating a strimmer etc, but not CTS, when I get the problem I hang my arm down in the daytime, or over the side of the bed at night, it goes almost instantaneously, it does occur when I rest my head on my arm at night, but what I have been doing previously before any CTS was gripping those hand exercisers to strengthen my grip, I noticed that although the CTS happens to my left hand mostly, occasionally my right hand twinges a bit now and again, although its predominant in my family history, I am 76 now and have never had any problems, where as the younger members of my family tend to get it, so my self diagnosis, obviously just for me in this instance, it is the hand grippers that are responsible would anyone agree, I hope this helps someone.

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Ella1910 said on 12 April 2013

I've just been diagnosed with cts but I know nothing about what treatment I will be receiving as the doctor who did the tests said I had to see my own doctor. Trying to find out if its from my job that I do I am support worker in health care and have been working with the elderly who do need lots of care. I'm wandering if I did it when repositioning clients when in bed or is it something else as never noticed these symptoms before. Also I need to know if can continue with my job as love working in the care sector

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anita howarth said on 04 April 2012

hello QueenEsther

could it be repetitive strain and not carpal tunnel?

i`ve just been diagnosed with CTS and fingers if u touch the inside tingle and feel quiet numb.
i got mine through being a sewing machinist for over 20 years florist and using computer hasnt helped .
hope you get things sorted

x Anita

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anita howarth said on 04 April 2012

i`m 45 female and have been just diagnosed with carpal tunnel , i`ve had 3 injections over a period of 3 months.the
injections worked really well but pain came back so surgery it is
although i`m slightly over weight i used to be a machinist for over 20 years then a florist, i use a computer and this is the cause of my CTS
i`ve been told by Rochdale infirmary that i`m on a 2 day standby so i`m just waiting now , cant wait as it hurting just writing this.
all being well with the right hand the left will be next.
so i`ll report back thank you Anita

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QueenEsther said on 23 August 2011

I have recently been diagnosed with carpal tunnel syndrome, and the only thing I ever did regularly with left hand was changing gears in car I drove for 26 years and recently gave up through pain in armpit which I had for 2 years and recently coupled with tingling in first two fingers.
After reading causes here I fins that it can be caused by many things, but I don't see from driving. Has anyone else had same symptoms who drives right hand drive cars regularly?

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