What is Carpal Tunnel?
Carpal tunnel syndrome is caused by pressure on the median nerve.
The median nerve runs from your forearm through a passageway in your wrist (carpal tunnel) to your hand. It provides sensation to the palm side of your thumb and fingers, except the little finger. It also provides nerve signals to move the muscles around the base of your thumb.
Anything that squeezes or irritates the median nerve in the carpal tunnel space may lead to carpal tunnel syndrome.
A wrist fracture can narrow the carpal tunnel and irritate the nerve, as can the swelling and inflammation resulting from rheumatoid arthritis.
There is no single cause in many cases. It may be that a combination of risk factors contributes to the development of the condition.
Carpal tunnel syndrome risk factors
A number of factors have been associated with carpal tunnel syndrome.
Although they may not directly cause carpal tunnel syndrome, they may increase your chances of developing or aggravating median nerve damage. These include:
- Anatomic factors A wrist fracture or dislocation, or arthritis that deforms the small bones in the wrist, can alter the space within the carpal tunnel and put pressure on the median nerve.
- Nerve-damaging conditions Some chronic illnesses, such as diabetes, increase your risk of nerve damage, including damage to your median nerve.
- Inflammatory conditions Illnesses that are characterized by inflammation, such as rheumatoid arthritis, can affect the lining around the tendons in your wrist and put pressure on your median nerve.
- Sex Carpal tunnel syndrome is generally more common in women. This may be because the carpal tunnel area is relatively smaller in women than in men.
- Alterations in the balance of body fluids Fluid retention may increase the pressure within your carpal tunnel, irritating the median nerve. This is common during pregnancy and menopause. Carpal tunnel syndrome associated with pregnancy generally resolves on its own after pregnancy.
- Other medical conditions Certain conditions, such as menopause, obesity, thyroid disorders and kidney failure, may increase your chances of carpal tunnel syndrome.
- Workplace factors It’s possible that working with vibrating tools or on an assembly line that requires prolonged or repetitive flexing of the wrist may create harmful pressure on the median nerve or worsen existing nerve damage.
What are carpal tunnel symptoms, and how to tell if you have carpal tunnel
- Tingling or numbness You may experience tingling and numbness in your fingers or hand. Usually the thumb and index, middle or ring fingers are affected, but not your little finger. Sometimes there is a sensation like an electric shock in these fingers.
- The sensation may travel from your wrist up your arm. These symptoms often occur while holding a steering wheel, phone or newspaper. The sensation may wake you from sleep, where symptoms are relieved by “ wringing” the hand.
- The numb feeling may become constant over time.
- Weakness You may experience weakness in your hand and a tendency to drop objects. This may be due to the numbness in your hand or weakness of the thumb’s pinching muscles, which are also controlled by the median nerve.
Carpal tunnel treatment and surgery
Initially a non-operative approach is used which includes the use of a night splint and avoidance of movements that aggravate symptoms. As symptoms progress over time, surgery can be considered especially if electrophysiological nerve tests confirm the diagnosis.
The surgery is performed by a hand surgeon in the operating room, and generally a full anaesthetic is not required: that is, a combination of local anaesthesia injected near the site of the cut, and sleep inducing medication is used.
A small cut near the junction of the wrist and hand is used and the nerve is identified and the tight structures overlying it are cut. The cut usually needs 2-3 stitches and a padded dressing and patients can go home the same day and carpal tunnel surgery aftercare instructions are given. You’ll follow-up with your hand surgeon at the 2 week mark for physiotherapy and wound checks.
This surgery is very successful in improving symptoms and is a routine surgery with a short surgery recovery time.