Traumatic Carpal Tunnel Syndrome
Carpal tunnel syndrome is a disease where the median nerve, which passes from the forearm onto the palm of the person’s hand is crushed or squeezed following repetitive injury or acute traumatic injury to the wrist. The median nerve must pass through the carpal tunnel which is made of ligaments supporting the wrist and hand and some of the bones of the wrist. The median nerve affects the sensation and movement of the thumb, the palm of the hand and the second through fourth finger, although the ulnar aspect of the fourth finger is often spared.
Whenever the area becomes irritated or injured and swelling occurs in the wrist, the median nerve will become compressed, causing paresthesias, numbness and weakness of the affected hand so that the patient will often drop things and be clumsier in the involved hand. Carpal tunnel syndrome is one of the most common nerve entrapment syndromes of the body.
Major Symptoms of Carpal Tunnel Syndrome
The symptoms will come on gradually if it is due to repetitive trauma but comes on more suddenly if acute trauma such as a fall or motor vehicle accident has contributed to the injury. People will experience burning, itching, tingling, numbness or pain in the palmar surface of the hand and in the thumb and second through fourth fingers. The patient may complain of a sensation of swelling of the hand, although no visible swelling can be seen.
The symptoms tend to be worse with repetitive motion of the wrist or when the patient is sleeping at night. When a person sleeps, there is a tendency to flex the wrists, which contributes to the symptoms. As the symptoms get worse, they occur more and more often during the day and become more severe. There can be atrophy of the muscles between the metacarpals when the syndrome has lasted several months. The muscles of the thenar eminence at the base of the thumb can also be atrophied. The patient will often try to “shake out” the symptoms without relief. Manual labor using the small muscles of the hand become very difficult to do. The sensation of heat and cold can be disrupted.
Causes of Carpal Tunnel Syndrome
Even in acute injuries, carpal tunnel syndrome tends to happen more often in people who have a congenital narrowing of the carpal tunnel so that, at the time of injury, there is less room for the median nerve to fit when there is swelling of the wrist. This has been borne out by studies of traumatic carpal tunnel syndrome in which it was found that patients who suffer traumatic carpal tunnel syndrome are at a higher risk of carpal tunnel syndrome on the uninjured side as well.
Non-traumatic causes of carpal tunnel syndrome include rheumatoid arthritis, hypothyroidism, pituitary gland hyperactivity, and the repeated use of hand tools that vibrate. Sometimes, carpal tunnel can be caused by diffuse swelling from fluid retention or by the development of a tumor or cyst in the carpal tunnel. Rarely, carpal tunnel syndrome can be completely idiopathic, with no known cause found.
Risk Factors for Carpal Tunnel Syndrome
Carpal tunnel syndrome is more common in women by a factor of 3:1 over men. This may be due to the fact that women naturally have narrower carpal tunnels than men have. It is more common in the dominant hand unless it is due to trauma to the non-dominant wrist. Diabetics and people with certain metabolic conditions affecting the ligaments and nerves have a higher chance of having compression of the median nerve. Besides direct trauma, the syndrome is more common in people working in industrial fields such as sewing, manufacturing and cleaning. Those who do repetitive assembly work are three times more likely to have carpal tunnel syndrome than people who type on a computer for a living.
Diagnosis of Carpal Tunnel Syndrome
In many cases, the diagnosis of carpal tunnel syndrome can be a clinical one in which the patient presents with the classical symptoms associated with the condition. The clinical work up should include inspection of the hand and wrist as well as evaluation of the sensation in the hand and the strength of the hand. Atrophy of the thenar eminence and of the hand muscles can be seen in severe cases.
The Tinel test is usually positive. This is a test where the physician taps on the median nerve, looking for shock-like feeling in the areas affected by the median nerve. The Phalen test is usually positive as well. In this test, the backs of the hands are pressed against one another forming a 90 degree angle at the wrist. The symptoms worsen when this maneuver is performed.
Nerve conduction studies can be undertaken to evaluate the nerve conduction through the median nerve. If this is abnormal, carpal tunnel syndrome can be diagnosed accurately. An ultrasound of the carpal tunnel can be done showing an increase in swelling of the median nerve. MRI has been attempted in diagnosing this condition but it hasn’t been found to be particularly helpful in diagnosing carpal tunnel syndrome.
Treatment of Carpal Tunnel Syndrome
The treatment of carpal tunnel syndrome can be surgical or non-surgical. The earlier the treatment is started, the greater is the chance than non-surgical treatment will work. Any underlying problems such as arthritis or diabetes need to be treated and the affected hand should be rested in a splint for about two weeks. Cold packs can be applied to the volar aspect of the wrist to reduce the swelling of the carpal tunnel and median nerve. NSAIDs can be helpful in reducing inflammation in some cases. Diuretics can be used to reduce local swelling and injections of lidocaine and injectable corticosteroids into the carpal tunnel can provide immediate but temporary resolution of symptoms. Vitamin B6 can help in some cases. Physical therapy can be done which will help to strengthen the hand and stretch the affected area. An occupational therapist can help sufferers who need alternative methods of performing fine motor activities.
Surgery is reserved for those cases that do not get better with conservative treatment. If the symptoms have been present for at least six months and conservative measures have failed, surgery is done which cuts into the band of tissue that surrounds the wrist so that the carpal tunnel is opened up, allowing for a decrease in the pressure on the median nerve. Symptoms of numbness, etc. are usually relieved right away after surgery but it can take months for the muscles to build back up and the arm to be fully functional again. Physical therapy is often required after surgery because cutting the carpal ligament can decrease the strength of the affected wrist. In the meantime, job restrictions may be needed. After surgery, most patients will recover full functionality of the hand and arm.
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