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, however may just be slightly more at risk.

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

Symptoms

The classic symptoms of carpal tunnel syndrome are pins and needles in the hand, mainly affecting 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. Other provoking activities are driving a car, reading a newspaper or riding a bicycle or motorbike.

The pins and needles are often associated with sense of swelling in the fingers and patients report their fingers feel like sausages in the night.

Occasionally in severe cases, the muscles on the front of the palm at the base of the thumb (thenar eminence) can waste, causing hollowing, this is shown in the photograph below. 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 pressure over the carpal tunnel at the level of the wrist whilst bending the wrist forward. When positive, this reproduces 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 at the level of the wrist and 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

Patients that have classical symptoms and physical examination of carpal tunnel syndrome do not routinely arrange need any tests or investigations.

Nerve conduction studies are a special test that 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.

In rare cases, an MRI scan of the neck is arranged, to investigate if the problem is coming from the neck.

Non-operative treatment

We would always discuss non operative treatment before considering surgery.

Simple painkillers and resting splints can offer help. The resting splints can be of particular benefit at night. Occasionally an ultrasound guided 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 or 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 painful tourniquet is not usually required as we perform the procedure using an adrenaline / local anaesthetic mixture to reduce bleeding.

The surgery can be performed open (through a 4cm incision) or endoscopic techniques (Keyhole, through a single 1cm incisions). The results seem to be the same for both techniques.

Mini-open technique

Local anaesthetic mixed with adrenaline (a vasoconstrictor to reduce bleeding and avoid a tourniquet) is infiltrated under the skin in line with the incision. Once completely 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 inserted under the skin (subcuticular) and small knots are tied at each end of the wound. Some butterfly stitches and a small dressing are placed over the wound. A light bandage is applied.

Endoscopic "key hole" technique

Local anaesthetic mixed with adrenaline (a vasoconstrictor to reduce bleeding) ais infiltrated under the skin in line with the carpal tunnel. A rubber band tourniquet is applied to reduce bleeding and optimise visualisation. Once completely numb, a small 1.5cm transverse skin incision is made on the volar aspect (palm side) at very end of the forearm just before the hand.

The proximal edge of the transverse carpal ligament is identified) as seen above as a shiny white band) and incised. The camera and in built knife is introduced into the carpal tunnel and is released under direct vision to allow the contents of the carpal tunnel to be decompressed.

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 and the small knots are either end of the wound can be snipped at 10 days flush with the skin.

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 covered, clean and dry until healed at about 7-10 days.

Return to driving : At all times you need to be able to handle your car in an emergency such as swerve out of the way of a dog or avoid a collision. 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. Everyone is different and you will need to make an informed decision as to whether you can control the car.

Return to work : Everyone has different work environments and it may be wise to seek advice from your surgeon on this. Light desk based activities may resume immediately post surgery but a return to heavy manual labour should be prevented for approximately 4-6 weeks. Premature return to heavy work may cause the tendons and nerve to scar into the released ligament.

Complications

More than 95% of patients 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.

Please look at my general hand complications page by clicking here but also see below for some specific complications

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).
Endoscopic - risk of inadequate view and convert to mini open technique.