Elbow Issues

Carpal Tunnel Syndrome

Causes
Any condition that makes the area inside the carpal tunnel smaller or increases the size of the tissues with in the tunnel can lead to symptoms of CTS. For example, a traumatic wrist injury may cause swelling and extra pressure within the carpal tunnel. The area inside the tunnel can also be reduced after a wrist fracture or dislocation if the bone pushes into the tunnel.

Any condition that causes abnormal pressure in the tunnel can produce symptoms of CTS. Various types of arthritis can cause swelling and pressure in the carpal tunnel. Fractured wrist bones may later cause CTS if the healed fragments result in abnormal irritation on the flexor tendons.

Other conditions in the body can produce symptoms of CTS. Pregnancy can cause fluid to be retained, leading to extra pressure in the carpal tunnel. Diabetics may report symptoms of CTS, which may be from a problem in the nerve (called neuropathy) or from actual pressure on the median nerve. People with low thyroid function (called hypothyroidism) are more prone to problems of CTS.

The way people do their tasks can put them at more risk for problems of CTS. Some of these risks include

  • force
  • posture
  • wrist alignment
  • repetition
  • temperature
  • vibration

One of these risks alone may not cause a problem. But doing a task that involves several factors may pose a greater risk. And the longer a person is exposed to one or more risks, the greater the possibility of having a problem with CTS. However, scientists believe that other factors such as smoking, obesity, and caffeine intake may actually be more important in determining whether a person is more likely to develop CTS.

In other instances, CTS can start when the tenosynovium thickens from irritation or inflammation. This thickening causes pressure to build inside the carpal tunnel. But the tunnel can’t stretch any larger in response to the added swelling, so the median nerve starts to squeeze against the transverse carpal ligament. If the pressure continues to build up, the nerve is eventually unable to function normally.

When pressure builds on the median nerve, the blood supply to the outer covering of the nerve slows down and may even be cut off. The medical term for this is ischemia. At first, only the outside covering of the nerve is affected. But if the pressure keeps building up, the inside of the nerve will start to become thickened. New cells (called fibroblasts) form within the nerve and create scar tissue. This is thought to produce the feelings of pain and numbness in the hand. If pressure is taken off right away, the symptoms will go away quickly. Pressure that isn’t eased right away can slow or even stop the chances for recovery.

Symptoms
One of the first symptoms of CTS is gradual tingling and numbness in the areas supplied by the median nerve. This is typically followed by dull, vague pain where the nerve gives sensation in the hand. The hand may begin to feel like it’s asleep, especially in the early morning hours after a night’s rest.

Sometimes pain may even spread up the arm to the shoulder. If the condition progresses, the thenar muscles of the thumb can weaken, causing the hand to be clumsy when picking up a glass or cup. If the pressure keeps building in the carpal tunnel, the thenar muscles may begin to shrink (atrophy).

Touching the pad of the thumb to the tips of the other fingers becomes difficult, making it hard to grasp items such as a steering wheel, newspaper, or telephone.