Carpal tunnel syndrome

Carpal tunnel syndrome is a common condition that results from compression of the median nerve at the wrist, where the median nerve passes through the "carpal tunnel". At Melbourne Hand Surgery we offer both the open and endoscopic surgery techniques to treat this condition. 

Anatomy

The carpal tunnel is located at the base of the hand where the median nerve and nine flexor tendons pass from the forearm to the hand. It is a tight, inexpansile passageway with a floor and walls made of bone (the 8 carpal bones) and a roof made of a tough tendon (the transverse carpal ligament).

The median nerve supplies sensation to the thumb, index, middle and half of the ring finger, plus most of the palm. It also supplies the muscles at the base of the thumb (the "thenar" muscles).

Symptoms

The most common symptoms are pain and numbness or tingling of the fingers and hand. People often complain that their affected hand feels clumsy and that they have trouble picking up things. They may wake at night with pain in the hands, wrist or up the arm. People commonly describe that when they wake up with pain they shake their hands to try to get rid of the pain. The symptoms may also be exacerbated by activities where the wrist is flexed, such as driving. In severe, longstanding cases there may be wasting (shrinkage) of the muscles at the base of the thumb, although this is rare (see photo above right).

Diagnosis

The condition may be diagnosed on the basis on your symptoms and examination findings. The presence and severity of the condition can be diagnosed with nerve conduction studies, which may be recommended by your GP or surgeon, especially if your symptoms are not "classical".

Causes

All of the causes of carpal tunnel syndrome result in the same problem: median nerve compression at the wrist. The most common cause is "idiopathic", which means that there's no particular reason for it to have occurred. Carpal tunnel syndrome can be related to pregnancy, diabetes, rheumatoid arthritis, osteoarthritis, broken wrist bones, hypothyroidism, obesity, acromegaly and (very rarely) tumours. Whether it can be caused by repetitive movements at work is controversial. Certainly if you have carpal tunnel syndrome you may find that certain work activities aggravate your condition.

Non surgical options

Splinting, anti-inflammatory medications, injections of corticosteroids and exercises can be successful in mild and moderate cases of carpal tunnel syndrome, especially when the condition has been present for less than 3 months. This is particularly so for women who develop carpal tunnel syndrome during pregnancy. The photo on the left shows an example of a thermoplastic splint made to treat carpal tunnel syndrome [photo credit].

There is limited evidence (see articles here and here) implicating vitamin D deficiency in carpal tunnel syndrome. We do not routinely check vitamin D levels in individuals who have carpal tunnel syndrome but if you have vitamin D deficiency (which can be diagnosed with a blood test through your general practitioner) it is not unreasonable to treat this. 

The following educational video on the technique of corticosteroid injection in carpal tunnel syndrome was created by NSW Hand Surgeon Dr Stuart Myers for general practitioners. It describes the anatomy of the wrist and shows what you can expect from a corticosteroid injection. Please note: contains a medical procedure (injection of the carpal tunnel).

Surgical options

Surgery involves division of the transverse carpal ligament, which is the ligament that runs over the top of the median nerve, forming the "roof" of the carpal tunnel.

The surgery can be performed as day case surgery through the open or endoscopic (keyhole) methods. Open carpal tunnel release surgery can be performed as wide awake hand surgery, so you don't necessarily have to have a general anaesthetic or sedation for the procedure. Endoscopic surgery is felt to provide a quicker recovery which may be particularly relevant for people who have both hands treated simultaneously. At Melbourne Hand Surgery we perform carpal tunnel surgery using both the open and endoscopic methods so we will discuss with you the benefits and risks of each method.

If you take anticoagulant medications for serious medical conditions it may be possible to continue these medications throughout the time of surgery, in consultation with your surgeon.

What can go wrong (complications)?

Major complications are rare with carpal tunnel surgery. These include damage to the median nerve during the surgery and complex regional pain syndrome. Other possible but unusual complications include wound infection, excessive swelling and stiffness, pain and discomfort, haematoma (a collection of blood in the area of surgery, which may require reoperation), keloid scars, delayed wound healing, or an allergy to any of the substances used during the surgery (antiseptic  solutions, anaesthetic agents, suture material or tapes).

Immediately after surgery

The local anaesthetic that is administered at the time of surgery will generally last for 6-8 hours. During this time you will not have pain but you will have numbness of your hand and fingers. The local anaesthetic may cause temporary numbness of your thumb and fingers. Occasionally the local anaesthetic lasts for 1-3 days. 

It is important to keep your hand elevated for 48 hours to reduce the risk of internal bleeding and to prevent post operative swelling. Keep the dressings dry and intact until your post operative review, or as directed by your surgeon. You may use your hand for light activities after 5 days, but do not perform any activity that causes pain. 

Recovery

Most people are not able to drive for at least one week after surgery and we recommend planning not to drive for two weeks. It is common to have sensitivity of the scar and pain when performing heavy lifting for the first few weeks. The duration of your anticipated recovery period relates to what you use your hand for - if you are a motor mechanic you will need to be able to put heavy loads through your hand before you feel fully recovered, so your recovery period may seem longer than someone who mostly uses their hand for typing. If you are able to take 10-14 days off work this is recommended. If your work involves heavy manual labour you may need to be on light or alternative duties for up to 12 weeks.

The pain of nerve compression can be expected to disappear quickly after surgery (providing that the carpal tunnel syndrome was the cause of your pain), because the blood flow to the nerve is restored by the surgery. If you have had numbness for a long time before your surgery it may take some weeks to months before you notice an improvement in this. In cases of severe carpal tunnel syndrome the nerve may not completely recover function. 

Your surgeon will commonly recommend that you see a hand therapist after the surgery, particularly if you are having difficulties with hand swelling, scar sensitivity, reduced mobility and pain. Sensory re-education may also be provided. You will be advised to perform finger and wrist extension and flexion exercises to ensure that the tendons glide smoothly past the site of surgery and do not develop adhesions that limit your range of movement or make your hand feel stiffer than it should.

It may take several months before you recover full grip strength. It is common to have some pain with deep pressure on the wound for a number of months. Regeneration of the nerve and the completion of the healing process will occur over 6-12 months.