What is carpal tunnel syndrome?
Carpal tunnel syndrome is a very common condition that causes numbness, pain and pins and needles in the hand. Very often the symptoms are worse at night and people tend to hang their arm over the side of the bed and shake the hand to try to relieve the tingling. Certain positions of the hand (e.g. driving) or repetitive use of the hand (e.g. sewing, typing) may aggravate carpal tunnel syndrome. Often carpal tunnel syndrome affects both hands at the same time.
What causes carpal tunnel syndrome?
Carpal tunnel syndrome is caused by pressure on the median nerve at the wrist. This nerve supplies feeling to the thumb, index, middle and half of the ring finger. The little finger and adjacent part of the ring finger are supplied by a different nerve (ulnar) and are therefore not affected in carpal tunnel syndrome. The nerve also supplies muscles in the hand so there may be a feeling of weakness of hand grip.
The median nerve passes across the wrist into the hand through the carpal tunnel. In cross-section, the bones of the wrist form a concavity which is bridged by a thick ligament. The median nerve and some tendons pass through this tunnel. In some people the ligament thickens and puts pressure on the median nerve causing carpal tunnel syndrome.
Why does it happen?
Most of the time there is no particular reason. In some people it can be due to activities such as using a jackhammer or repeated pressure on the wrist. Rarely it can be caused by a fractured wrist or an arthritic wrist. Some rare diseases such as acromegaly can also cause carpal tunnel syndrome. Pregnancy is a common cause of carpal tunnel syndrome due to fluid retention and the symptoms usually resolve after delivery.
How is it treated?
If there is an obvious general cause, this is treated or avoided as appropriate. Occasionally night splints may help if the symptoms only occur at night. Some people use steroid injections, but repetitive injections can cause damage to the nerve or underlying tendons.
Very often the symptoms are only mild and no treatment is necessary.
If the symptoms are severe enough, carpal tunnel syndrome can be treated surgically.
Carpal tunnel release
Prior to surgery, the diagnosis will be confirmed with nerve conduction studies. This is a simple test that measures how well the nerve is working. If there is compression of the nerve it will not conduct an electrical impulse as well across that point. Occasionally an ultrasound will be used to confirm the pressure on the nerve or to look for other causes such as a cyst from an arthritic joint.
Except in unusual circumstances, the operation is done as a day patient (ie admitted in the morning and go home the same day after the operation). If both hands are affected, the worse one would usually be done first and the other delayed until the first has healed. Having one hand out of action is fairly easy to cope with but both at once is much more difficult, even for a short period of time.
The operation can be done under general or local anaesthetic with a little sedation. In most cases this can be your choice but this should be discussed with the anaesthetist first. The skin incision is about 2.5 centimetres long and extends from the wrist crease into the palm, close to the midline.
Directly beneath the skin is the thick ligament. This is carefully divided in the middle portion until the nerve is seen. The rest of the ligament is then divided in both directions with scissors, with the median nerve under direct vision. The tightness in the ligament causes it to spring apart when it is divided and the pressure on the nerve is released. The skin is then closed with several (5 or 6) stitches. An adhesive dressing is applied and covered with a larger cotton wool and gauze dressing.
What to do postoperatively
It is good to keep the hand a little elevated at first to reduce any swelling. It does not need a sling (it is better to keep it moving) but it will help to hold the hand above waist level for the first day or so. During the first night the arm can be elevated on a pillow at your side. Simple analgesics such as Panadeine or Nurofen are usually sufficient for any postoperative discomfort. The outer dressings can be removed the morning after surgery and the adhesive dressing on day 3. The wound should be kept dry until after the adhesive dressing is removed. It can then be left open to the air but try not to expose it to obvious sources of infection in the first week (eg wear gloves if doing gardening etc). You should return to the Neurosurgery Ward one week after surgery to have the sutures removed and you will be given an appointment to see me again in 4 to 6 weeks. If you do not have an appointment, please call my secretary on the next working day to make one. It should be possible to do most fine things with the hand immediately but it will be painful to do things requiring strength (eg cutting up your food) for a few days. Time off work will depend on your job but usually should not exceed two weeks.
What to expect from the surgery
Usually the pins and needles and pain are relieved or improved immediately, but occasionally may take a little longer. Numbness and weakness may take several months to go away and it is common to be left with mild permanent sensory changes in the tips of the fingers if there was severe numbness preoperatively. The wound will be lumpy and tender to start with but will gradually settle down. The part over the heel of the hand will take the longest and it will be painful to do things like push yourself up from a chair for a few weeks. Over a few months the wound will flatten right out and the redness will disappear, leaving a thin line just like the normal lines on your hand. Some people develop more prominent scars but this is uncommon.
Are there risks involved?
There are risks involved with anything in life and surgery is no different. Some of these risks are common to most or all operations and some are specific to the particular procedure.
The following are the most common or most serious complications. Other problems may occur rarely and it is impossible to list every one of them. Just try to list all of the possible things that could happen on your drive to work-a car crash is obvious; an aeroplane crashing onto the road in front of you is also possible but extremely unlikely and would not normally be considered common enough to affect your decision to drive. If there is anything in particular that you are concerned about, please ask me.
General risks of any operation
Anaesthetic complications such as heart attack, drug allergy or even death are possible but very rare.
Blood clots in the leg (DVT) or lung (pulmonary embolus) may occur unexpectedly but are very uncommon in otherwise healthy people.
Infections such as pneumonia, wound infection or urinary tract infection may occur after any operation.
Bleeding may occur especially in people taking aspirin. It is therefore recommended to cease aspirin (also called Cartia or Disprin) two weeks before elective surgery.
The most common complication would be a superficial wound infection that resolves with antibiotics. Damage to the nerve is the most serious local complication and if it does occur it may cause numbness, weakness and pain in the hand. Fortunately it is very uncommon.
Coming into hospital for surgery
These days, most operations are done on the same day as admission. You will need to come to the hospital admissions area and will be admitted to the day surgery unit. We will notify you of the admission time. If you have not already sent in the hospital admission forms, bring them with you.
You will need to fast for 6 hours which means nothing to eat or drink after the time notified.
You will usually be able to take your normal tablets but medications that affect your bleeding will usually be stopped preoperatively. Aspirin, (also called Disprin or Cartia),and Plavix (also called clopidogrel) should be stopped for two weeks if possible before an elective operation. Fish oil should be stopped for a week. Anti-inflammatories should be stopped for 48 hours. Warfarin will need to be discussed with me and your GP.
I will see you in hospital before you go to the operating room and the anaesthetist will also see you preoperatively and will want to know about your general health and any medications you are on. Please bring your usual tablets with you.