Carpal tunnel syndrome
Carpal tunnel syndrome occurs because the median nerve is compressed in a narrow tunnel on the palm side of the wrist. Besides the nerve, the flexor tendons also run through this tunnel, and there is not much room to spare.
The most recognisable sign is night-time tingling and numbness of the fingers that wakes you up. The thumb, index finger, middle finger and half of the ring finger are affected. The little finger is usually spared, which is typical of this condition.
People often describe shaking their hand after waking, hanging it over the edge of the bed or holding it under running water until the feeling eases. This is not a minor detail, but one of the more reliable descriptions a doctor hears.
How it shows during the day
During the day, numbness appears during tasks where the wrist stays in the same position for a long time: while driving, or when holding a phone, a hairdryer or a book.
As the condition progresses, clumsiness and a weaker grip follow. Things fall out of your hands, buttons and keys become fiddly, and the feeling in your fingertips is duller.
With long-standing compression, the muscle pad at the base of the thumb visibly wastes. This is a sign that the nerve has been suffering for some time, and a reason for quicker care.
What increases the risk
Work involving repetitive wrist movements, a strong grip or vibrating tools increases the strain. The keyboard and mouse are often blamed, but the evidence for them is considerably weaker than for physical work.
Other factors are often more important: pregnancy, an underactive thyroid, diabetes, rheumatoid arthritis, a previous fracture or injury of the wrist and increased body weight.
In pregnancy it is often a temporary form that settles after the birth. This does not mean it does not need to be treated during pregnancy.
When it is not the carpal tunnel
If weakness or numbness of the whole arm appears suddenly, especially together with a drooping corner of the mouth, slurred speech or weakness of the leg on the same side, call 112. These are signs of a stroke and have nothing to do with the wrist.
Sudden severe pain, swelling, or a pale or cold hand after an injury or after a plaster cast has been fitted requires immediate assessment.
When the tingling affects both hands and also the legs, when it spreads along the neck and shoulder blade or when it progresses quickly, it may be a problem in the cervical spine or a disease of the nerves. A neurological examination is then needed, not a procedure on the wrist.
How it is confirmed and how it is treated
Care begins with a conversation and a clinical examination, in which the doctor assesses the feeling in your fingers, grip strength and the muscle pad at the base of the thumb, and carries out tests that provoke the compression. Electromyography with measurement of nerve conduction is used to confirm the diagnosis and to assess the degree of damage. Whether you need it and where to have it done is agreed at the examination.
For milder forms, a night splint that holds the wrist in a neutral position, adjusting physical demands at work and treating any underlying disease, if there is one, are often enough. Some people are helped by an injection of an anti-inflammatory medicine into the tunnel, whose effect is often temporary.
When symptoms persist, when strength is declining or when electromyography shows advanced damage, surgical release of the tunnel makes sense. The procedure is done under local anaesthesia and relieves the nerve by cutting the ligament above it.
Compression of peripheral nerves is treated by the neurosurgery clinic. Care is self-pay, you do not need a referral, and appointments are booked with the clinic that runs the service. Bring the results of previous tests, especially electromyography if you already have it.