Carpal Tunnel Syndrome

Mr Mike Hayton
FRCS(Trauma and Orth) FFSEM (UK)
Consultant Orthopaedic Hand Surgeon

Other common names

None

Who does it affect?

It can occur in any patient but is more common in females over the age of 40 years.

Why does it occur?

In the majority of patients, the cause is still unknown. However there are a number of medical conditions that predispose patients to Carpal Tunnel syndrome. These include pregnancy, thyroid disease, rheumatoid arthritis and wrist injuries. It is important to note that if you have one of these conditions it does not mean that you will definitely develop carpal tunnel syndrome, hwever may just be slightly more at risk.

Carpal tunnel syndrome occurs when the median nerve is compressed at the level of the wrist. The nerve and tendons that bend the fingers pass from the forearm into the hand through a narrow tunnel called the carpal tunnel. When there is a build up of pressure in this tunnel the nerve becomes squashed and causes symptoms of carpal tunnel syndrome.

Symptoms

Pins and needles in the thumb, index and middle fingers. This commonly occurs at night and the patient is often awakened from sleep and has to shake their hands to gain relief from these symptoms. Occasionally in severe cases, the muscles on the front of the palm next to the thumb can waste, causing hollowing. In such severe cases the thumb may become weak or clumsy.

As cycling is increasing in popularity we are seeing more patients develop carpal tunnel syndrome after 10 miles or so on a bike. There are some pretty easy initial techniques that can minimise these symptoms - see below

Clinical Examination

Modified Phalen's test - This is a test where we apply direct pressure over the carpal tunnel whilst bending the wrist forward, and when positive may reproduce the pins and needles in the thumb, index and middle fingers.

Tinel's test - This involved tapping the skin that lies over the nerve in the carpal tunnel may cause tingling in these fingers.

In advanced cases muscle wasting can be seen on the palm side of the thumb as shown in this photograph. 

 

Investigations

Nerve conduction studies are used to record the speed of the nerve across the wrist joint. This can be compared to the other hand, or in cases where both hands are affected, compared to normal population data. The test takes about 20 minutes and is slightly uncomfortable.

However if a patient has classical symptoms and physical examination of carpal tunnel syndrome, I do not routinely arrange these studies.

Non-operative treatment

Simple painkillers and resting splints can offer help. Occasionally a steroid injection into the carpal tunnel will improve symptoms.  The last trimester of pregnancy is notorious for causing carpal tunnel syndrome, in such cases a splint of steroid injection can help. However on the birth of the baby the symptoms usually resolve over the coming months.

However, most patients who do not want an injection or the injection only gives temporary benefit from surgery.

Advice for cycling induced carpal tunnel syndrome

The position of the hand and wrist during cycling does predispose to carpal tunnel syndrome. I know from personal experience a few top tips that can aid ease the symptoms and avoid surgery. If possible, every 1-2 miles on a long ride, make a fist and squeeze the hand 10-15 times. This will help "squeeze out" a build up of interstitial fluid in the hand and reduce the pressure in the carpal tunnel. Tri-bars can help by avoiding the prolonged position of extension and flexion that the wrist finds itself when on standard handle bars.

Operative treatment

Most patients who have troublesome carpal tunnel syndrome have surgery. The surgery is a day case procedure usually under local anaesthetic and takes about 10 minutes. A tourniquet is not required.

The surgery can be performed open (through a 4cm incision) or endoscopic techniques (Keyhole, through one or two 1cm incisions). The results are the same for both techniques, however I prefer to perform the surgery through the open technique as I can directly visualise the nerve throughout the operation.

Open technique

Local anaesthetic is infiltrated under the skin in line with the incision. Once numb, the skin is incised and then the underlying fat is retracted.

Care is taken not to injure sensory nerves to the palm. At the base of the wound is a thick band of tissue called the transverse carpal ligament. This structure needs to be released to allow the contents of the carpal tunnel to be decompressed.

Having released this ligament the contents of the carpal tunnel are inspected to ensure adequate release and no other conditions are present. 

The skin is sutured with fine absorbable sutures and a bulky dressing is applied.

Post-operative rehabilitation

The patient is fit to go home soon after the operation. The anaesthetic will wear off after approximately 6 hours. Simple analgesia usually controls the pain and should be started before the anaesthetic has worn off. The hand should be elevated as much as possible for the first 5 days to prevent the hand and fingers swelling. Gently bend and straighten the fingers from day 1. My preference is to remove the dressing at 2 days. The wound is cleaned and redressed with a simple dressing. Avoid forced gripping or lifting heavy objects for 2-3 weeks. The sutures dissolve at about 2-3 weeks.

You should notice an improvement in symptoms within a week but the final result may be realised at about 3 months.

Click here to download a pdf on post operative instructions

Return to activities of daily living

It is my advice to keep the wound dry until healed at about 7-10 days.

Return to driving : The hand needs to have full control of the steering wheel and left hand the gear stick. It is probable advisable to delay return to driving for a few days.

Return to work : Everyone has different work environments. Return to heavy manual labour should be prevented for approximately 4-6 weeks. Early return to heavy work may cause the tendons and nerve to scar into the released ligament. Please ask your surgeon for advice on this.

Complications

Overall, greater than 95% are happy with the result. However complications can occur.
There are complications specific to Carpal Tunnel Release and also general complications associated with hand surgery.

General complications:

 - Infection (Less than 1%),
 - Neuroma (Less than 1% coiled painful nerve bundle)
 - Numbness

Chronic regional pain syndrome  (1-2% rare reaction to surgery with painful stiff hands - this can occur with any hand surgery from a minor procedure to a complex reconstruction.)

Specific complications:

Failure to completely resolve the symptoms (approximately 5% - this may be due to chronic scarring of the nerve due to long duration of pre-operative pressure, symptoms suggesting this include muscle wasting and severe numbness.
Pillar pain (less than 2%), a poorly understood complication with pain on the front of the wrist,
Numbness in the palm (less than 1%, a small branch of the nerve passes across the skin incision, care must be taken too avoid injury to this).