The carpal tunnel is the name given to an anatomical space situated at the wrist which holds a bundle of tendons, blood vessels and the median nerve. Carpal tunnel syndrome refers to a condition whereby the pressure within the carpal tunnel increases and irritates or compresses the median nerve. This results in tingling and numbness in the hand, in the area supplied by the median nerve, as shown in the diagram.
There are various causes of carpal tunnel syndrome including:
- Degenerative or injury related changes to the wrist joint
- Systemic conditions causing inflammatory changes at the wrist joint including rheumatoid arthritis and certain metabolic disorders
- Workplace factors including using display screen equipment or manual work involving sustained pressure on the wrist and palm
The most common symptoms are tingling and numbness in the palm of the hand involving the thumb, index, middle and adjacent half of the neighbouring ring finger. Commonly initial symptoms are mild and intermittent with tingling after repetitive activities or when the wrist is flexed (bent forward in the same direction of the palm). It is common to experience symptoms at night and classically patients will shake their hand (‘a positive flick sign’) or drop the hand over the edge of the bed to obtain relief. Fortunately, in 30% of cases symptoms will resolve with no treatment. However, if symptoms do not settle they may progress and result in weakness of function or wasting of muscle strength around the thumb.
Carpal tunnel syndrome can often be reliably diagnosed by your doctor or physiotherapist by taking a history of your condition and by conducting a physical examination. The main feature on examination is often a reproduction of symptoms when holding the wrist in sustained flexion by moving the palm of the hand towards the wrist or when tapping or pressing over the median nerve in the carpal tunnel.
X-rays and scans are not routinely required but if surgery is being considered nerve conduction studies may be requested to confirm the severity of median nerve compression.
Many patients wish to know what they can do themselves to prevent or treat CTS. Unfortunately ,the options are rather limited but it is possible to make a few suggestions.
- Relative rest and change in aggravating activities – if you find that a particular activity reliably aggravates symptoms then it is probably worth trying to either do less of that activity or find an alternative way of doing it.
- Ergonomic changes – Carpal tunnel is often aggravated by repetitive activities or sitting with the wrist in flexion, for example when driving or at a computer. Try to find ways of changing your set up and take regular breaks from activity
- Splints – these can be obtained from your local pharmacist or on line at reasonable cost. The advice is to wear at night and when doing aggravating activities. If there is no improvement within 6 weeks it is unlikely to resolve the symptoms. Avoid wearing them all the time as the wrist may stiffen and muscles become weak
- Weight loss – If you are significantly overweight weight loss may help ease the symptoms
Corticosteroid injection therapy
If you have weakness or muscle wasting or persistent numbness then surgery is recommended. However for individuals with carpal tunnel syndrome who continue to suffer sensory (tingling and numbness) symptoms in spite a course of non-surgical management (outlined above) a corticosteroid injection can be offered as the next line of treatment. You can read more about local corticosteroid injections here.
Evidence for the effectiveness of a steroid injection is good for short term relief with evidence for more prolonged relief not as strong. A figure of 50% relief at 1 yr is a reasonable guide.
Carpal tunnel decompression surgery is an effective option for individuals who:
- Have constant sensory symptoms (numbness & tingling or pins and needles)
- Weakness or wasting of the thumb muscles
- Have significant pain or sensory symptoms which disturb sleep or daytime activities and have trialled non-surgical intervention for at least 3 months.
Carpal tunnel syndrome surgery is a treatment to relieve pressure, pain, numbness and tingling in the hand and arm caused by the nerve that crosses the front of your wrist (the median nerve) becoming trapped.
The median nerve is one of the two main nerves in the hand. It provides sensation to the thumb, index, middle and part of the ring fingers. It also supplies minor muscles in the hand.
On its way to the hand, it passes through a tunnel made by the wrist bones (the carpus) and a ligament which forms the roof (hence 'carpal' tunnel). The nerve shares this space with the flexor tendons which are the main gripping tendons of the fingers.
When the lining of the tunnel or the sheaths of the tendons thicken, the nerve, which is the softest structure, is compressed and symptoms are felt in the area it supplies.
This leads to tingling in the fingers, later loss of feeling, some pain and often night symptoms when the hand wakes the patient because of unpleasant tingling and numbness.
In the initial stages, the lining of the tunnel can be made to thin by injections. This increases the available space in the tunnel.
Splints can also be worn to relieve symptoms. The nerve is more pinched when the wrist is bent, therefore a splint prevents bending and thus relieves symptoms.
When these measures fail or if the condition is severe, surgery is the next option. This is called a carpal tunnel release and involves cutting of the ligament which is compressing the nerve. This is done through a small cut in the skin of the heel of the hand, close to the wrist. This has the effect of relaxing the tunnel.
Occasionally carpal tunnel surgery will need to be preceded by nerve conduction study, which is an investigation to map out the nerve and identify where, and how severely, it is being compressed.
This surgery is performed under local anaesthetic injection at the wrist, and is a short operation usually performed as an outpatient procedure, meaning you may not require an overnight stay.
The cut in the hand is stitched up using sutures which are removed within two weeks. After this, your hand can return to full use.
Following carpal tunnel syndrome surgery, it is important to elevate the hand at all times for two weeks. A sling is provided but it need not be worn all the time as long as the hand is kept above the level of the heart. You must keep the fingers moving through their full range, straightening them fully and rolling them into a fist fully, and you must not use, or dangle, the hand.
A carpal tunnel operation usually removes all related symptoms, particularly if these are of recent onset. Those who have had compression for a long time, or diabetic patients, may not resolve all symptoms.
The scar, in the heel of the palm, usually heals to a very fine, pale line but it may be tender for some weeks after surgery.
Recurrence of carpal tunnel syndrome, after effective surgery, is rare.