There are three major nerves that supply sensation to the upper limbs and hand and these are the radial, the median and the ulnar nerves. Damage to any of these nerves can lead to altered sensation or altered muscle power distal (or further away) to where the injury occurs. The classic example of this is when you hit your funny bone at the elbow - which for most people is decidedly un-funny. The result being an often excruciating pain followed by pins and needles down the inside of your forearm and affecting the little and ring fingers too – the bit coloured green in the illustration above.
The median nerve, irritation to which is the underlying cause of carpal tunnel syndrome, is vulnerable at the level of the wrist. The reason is because of the tight and tough surrounding structures that make up our wrists and the median nerve being the softest structure within the wrist.
The carpal tunnel gets its name from the small, square carpal bones that make up the back half of the wrist, and tunnel because the carpal bones form a tunnel. Lying within the carpal tunnel are the long, solid flexor tendons and the median nerve, a relatively soft and vulnerable structure.
In conditions where there is increased pressure within the carpal tunnel, it’s the median nerve that suffers, warning you that there is a problem with pins and needles in the thumb and first two digits. This is often worse at night and is enough to wake sufferers up with pain and tingling. If the pressure was to increase then further damage could be done and sensation can be lost, resulting in numbness to the affected fingers - and this can be permanent. Fluid retention within the tunnel can precipitate the problem, and women who are susceptible to carpal tunnel syndrome can often get their first symptoms when they become pregnant as fluid retention is more likely to occur. Further along the time scale, people who suffer from arthritis, where thickening can occur not only around joints but around tendons too, may also become victims to carpal tunnel syndrome.
Thankfully treatment is often very efficient and effective. A small steroid injection into the carpal tunnel can rapidly remove inflammation and swelling and take the pressure of the afflicted nerve. If that fails then a simple surgical procedure will physically remove the pressure from the nerve and cure the problem.
However, numbness may not always be as simple as carpal tunnel syndrome. My other friend was sent for surgery on both his affected hands but sadly the results were not good and he still has the problem. But he also has a far more challenging problem that I suspect is also playing a major role in his situation: he has diabetes.
Poorly controlled diabetes is notorious for producing serious consequences, the more common ones being heart disease, kidney disease and eye disease. But it can also affect the circulation and the peripheral nerves. Diabetic peripheral neuropathy differs from carpal tunnel syndrome in that it doesn’t limit itself to one nerve - it affects all peripheral nerves and more commonly will start in the feet, often described as a “sock like” distribution. The sad thing is that once the nerve is damaged, currently we have no way of resurrecting its function. Patients with peripheral neuropathy usually complain first of a burning sensation which progresses to numbness and it will take the expertise of a doctor or specialist to determine the extent, type and severity of the problem.
If you do suffer from altered sensation in your fingers or toes and it’s not going away, you must get it checked out. If you are a diabetic, it is so important to keep your blood sugars under good control and do everything you can to maximise your health and minimise the risks that diabetes can pose. And if you bang your funny bone you’ll know exactly what a neuropathy is, and you’ll have my complete sympathy!