Carpal Tunnel Syndrome

What is Carpal Tunnel Syndrome?

Carpal tunnel syndrome is a condition affecting one of the main nerves in the wrist area. The carpal tunnel is a space created by the natural arch of the wrist bones. A thick band called the transverse carpal ligament creates a roof to the tunnel. This means that the size of the tunnel cannot change, as the bones and ligament act like solid walls. Nine tendons that bend the fingers and thumb and the median nerve pass through the tunnel. The median nerve provides feeling (sensation) to the skin of the thumb, index and middle fingers, as well as half the ring finger. The nerve also provides the communication line to the muscles at the base of the thumb (thenar muscles). (See Below)

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The most likely cause of carpal tunnel syndrome is extra pressure on the median nerve at the wrist inside the tunnel. This extra pressure can come from swelling (inflammation) of the contents inside the tunnel. When pressure results in nerve symptoms, it is called a compressive neuropathy. While the exact carpal tunnel syndrome causes are usually unknown and due to the patient’s personal anatomy, there are many factors that can contribute to the increased pressure or inflammation, including:

  • Rheumatoid arthritis
  • Gout
  • Amyloidosis
  • Infections
  • Psoriatic arthritis
  • Arthritic spurs of the carpal bones
  • Tumors
  • Ganglion cysts
  • Wrist fracture or dislocation of the wrist
  • Repetitive motions performed at work or home

Even making a tight closed fist or holding the wrist in bent or extended positions can put increased pressure on the median nerve. A prolonged or constant fist or bend (like a fist during sleep, reading a book, or some other activities) may put enough pressure to cause the numbness/tingling. If the funny feeling in the fingers just began, this is easily resolved by moving the fingers back and forth and out of the position. If the pressure continues off and on for weeks to months, the symptoms may come on faster after the activity or wrist position is created. It may also take longer for the symptoms to go away after the activity stops. Eventually, symptoms can become constant.

Repetitive activities in the workplace with forceful or repetitive gripping or vibration can also increase symptoms. However, it is complicated to determine if the work activity is the main cause of the symptoms or if work is incidentally just aggravating a condition that is already present (unrelated to work). The determination of cause of symptoms requires experienced and specialized health care providers to provide an opinion, taking many factors into account.

There are some risk factors that increase the chances of getting carpal tunnel syndrome. For example, women are more likely than men to experience carpal tunnel syndrome. It is more likely to occur with aging. Each decade someone is alive, there are more people that experience carpal tunnel syndrome. Thus, it is rare in children and adolescents and more common in ages 40 and over. Carpal tunnel syndrome is more common in people with obesity, diabetes, alcohol addiction, fibromyalgia and hypothyroidism. If you have carpal tunnel syndrome, your children may be more likely to get it. Also, during pregnancy, hormonal changes and extra body fluid retention may add swelling and pressure into the tunnel.

While symptoms can sometimes be worse at night, sleep has not been shown to cause carpal tunnel. Some people get symptoms while driving a car. This is also not necessarily the primary cause of the problem. The wrist position during driving or sleep, for example, may simply aggravate the symptoms.