What is Carpal Tunnel Syndrome?


Carpal tunnel Syndrome is an entrapment neuropathy. These are a group of conditions where nerves become squashed and stop working properly. Many people have experienced this, when sitting in a strange position. We often describe it as “the leg going to sleep”. Carpal tunnel syndrome is brought on by a pinched nerve at the wrist. Symptoms include numbness and tingling in the fingers. Some people may present with pain in the arm, hand, and fingers.
 

What causes Carpal Tunnel Syndrome?


There is a space in the wrist called the carpal tunnel where the median nerve and nine tendons pass from the forearm into the hand. Carpal tunnel syndrome occurs when the tunnel becomes tight and the pressure on the nerve increases. When the pressure becomes great enough to disturb the way the nerve works, numbness, tingling, and pain may be felt in the hand and fingers.
The median nerve supplies the thumb, index,middle and half the ring finger with sensation

The increased pressure may be due to two causes:
• The tunnel changes shape
• The contents of the tunnel swell
In some patients, notably those with Rheumatoid arthritis but also some other conditions the synovium (lining around the tendons) swells. We call this synovitis. Fortunately this is a rare cause of CTS.
The vast majority of patients fall into the first group, the tunnel changing shape. Some of this is due to wear and tear in the tissues and ligaments. We still do not fully understand the cause. There is some association with the shape of the hand long and thin versus short and broad.
A very few patients can develop ganglions and other lumps within the tunnel and develop symptoms.

 Who gets Carpal Tunnel Syndrome?


Predominantly ladies develop CTS, usually in a ratio of 6 women to one man. It has been suggested that this is because women work harder than men!! The commonest age range is 40-60 years but we are now seeing it in children and more frequently in the over 60s.
The condition is very prevalent in people with diabetes and also in those with renal failure requiring dialysis.
Pregnancy is another cause of CTS, but fortunately the symptoms resolve in the majority of patients after delivery, although I think the majority will turn up again in my clinic a few years later. Some authors have put the incidence as high as 18% in the last 3 months.
 

What are the symptoms?


Most people will complain of pins and needles affecting their whole hand. Further questioning may find that the thumb, index and middle are the worst affected with the ring finger slightly affected and the little finger spared. Some people will describe this as pain. 
Many people will describe waking up in the night with their hands feeling dead or numb, some people say that their fingers feel like sausages.
Initially the symptoms are intermittent. They will commonly occur at night or when driving. Holding the wrists bent will also bring on the problem.
As the problem becomes more severe then the symptoms will start to last longer during the day. If the numbness is present all the time then the condition is getting serious and we would recommend urgent surgery.
Patients often find that shaking the hand gives relief of symptoms as does hanging the hand out of bed at night.
 

What is the Anatomy?


The bones of the wrist at the base of the thumb form an arch opening at the palm. Joining the ends of the arch is the transverse carpal ligament or flexor retinaculum, two names for the same structure. This ligament is approximately 2.5cms square. 
In the tunnel so formed is the Median nerve and the tendons (guiders) to the fingers and thumb.

 

How doe we confirm the diagnosis?


The best way of making the diagnosis is on the history which is then confirmed by clinical testing. There are several tests we can use:
  • Phalens test. Here we maintain the wrist in a fully flexed position for upto a minute. The test like all of those listed here should reproduce the symptoms.
  • Reverse Phalens: as above but backwards
  • McMurtry’s test: here we apply pressure at the base of the palm over the median nerve.
  • Durkan’s test: similar to McMurtry’s but the pressure is applied somewhat more distally.
  • Tinels Test. Here we tap over the nerve at the wrist. If the test is positive an electric shock feeling should be felt in the fingers.

I now almost routinely do nerve conduction studies to check the diagnosis for several reasons.
  • To confirm the diagnosis
  • To assess the severity of the carpal tunnel syndrome. If you have severe damage on your nerve tests then you wont get a perfect result afterwards. I would rather explain that before the operation than try to explain it afterwards.
  • To exclude other problems. Many patients with carpal tunnel syndrome will also have cubital tunnel syndrome or neck problems. If these are missed before surgery and you don’t make a full recovery, it is embarrassing trying to explain why you need a second operation!

 

How do we treat it?


If the symptoms are mild or you are pregnant then we will start with a splint to be worn mainly at night time.
If the symptoms are slightly more severe or you do not want surgery then a steroid injection may be useful. The steroid injection is not particularly painful and will have a 50% chance of producing long term (>6months) benefit.
The majority of patients however will require surgery.
 

Will it get better on its own?


Probably no more than 5% of patients who consult a surgeon will see a spontaneous improvement.
 

Doesn’t surgery hurt?


Very little. Most patients will require no more than 3 or 4 doses of paracetamol after the operation.
 

Which type of surgery should I go for?


There are four types of surgery:
The blind push technique has many advocates but I wouldn’t have it done that way so I don’t offer it. 
I do both open and endoscopic techniques. The open technique is used for those patients who are suspected to have abnormal anatomy, have had previous surgery or in whom I think there are other reasons not to do endoscopic release. 
For all other patients I recommend endoscopic surgery.
The advantage of endoscopic is the small scar, rapid return to activities and reduced tenderness in the palm. From the surgeons point of view the big advantage is the better visibility and the knowledge of what you are dealing with.
 

Is this just another name for RSI?


No. You will notice that nowhere on the site do we suggest that work plays any part in the causation of carpal tunnel in the vast majority of patients.