Carpal tunnel syndrome
Carpal tunnel syndrome: Excerpt from Professional Guide to Diseases (Eighth Edition)
Carpal tunnel syndrome, a form of repetitive stress injury, is the most common of the nerve entrapment syndromes. It results from compression of the median nerve at the wrist, within the carpal tunnel. This compression neuropathy causes sensory and motor changes in the median distribution of the hand.
Causes and incidence
The carpal tunnel is formed by the carpal bones and the transverse carpal ligament. Inflammation or fibrosis of the tendon sheaths that pass through the carpal tunnel commonly causes edema and compression of the median nerve. Many conditions can cause the contents or structure of the carpal tunnel to swell and press the median nerve against the transverse carpal ligament. Such conditions include rheumatoid arthritis, flexor tenosynovitis (commonly associated with rheumatic disease), nerve compression, pregnancy, renal failure, menopause, diabetes mellitus, acromegaly, edema following Colles’fracture, hypothyroidism, amyloidosis, myxedema, benign tumors, tuberculosis, and other granulomatous diseases. Another source of damage to the median nerve is dislocation or acute sprain of the wrist.
Carpal tunnel injury is five times more common in women than in men. It usually occurs in women between ages 30 and 60 and poses a serious occupational health problem. Assembly-line workers and packers and people who repeatedly use poorly designed tools are most likely to develop this disorder. Any strenuous use of the hands — sustained grasping, twisting, or flexing — aggravates this condition.
Signs and symptoms
The patient with carpal tunnel syndrome usually complains of weakness, pain, burning, numbness, or tingling in one or both hands. This paresthesia affects the thumb, forefinger, middle finger, and half of the fourth finger. The patient is unable to clench his hand into a fist; the nails may be atrophic, the skin dry and shiny. (See The carpal tunnel.)
Because of vasodilatation and venous stasis, symptoms are typically worse at night and in the morning. The pain may spread to the forearm and, in severe cases, as far as the shoulder or neck. The patient can usually relieve such pain by shaking or rubbing his hands vigorously or dangling his arms at his side.
Diagnosis
Physical examination reveals decreased sensation to light touch or pinpricks in the affected fingers. Thenar muscle atrophy occurs in about half of all cases of carpal tunnel syndrome, but it’s usually a late sign. The patient exhibits a positive Tinel’s sign (tingling over the median nerve on light percussion) and responds positively to Phalen’s wrist-flexion test (holding the forearms vertically and allowing both hands to drop into complete flexion at the wrists for 1 minute reproduces symptoms of carpal tunnel syndrome). A compression test supports this diagnosis: A blood pressure cuff inflated above systolic pressure on the forearm for 1 to 2 minutes provokes pain and paresthesia along the distribution of the median nerve.
Electromyography and nerve conduction velocity detect a median nerve motor conduction delay of more than 5 milliseconds. Other laboratory tests may identify the underlying disease.
Treatment
Conservative treatment should be tried first, including resting the hands by splinting the wrist in neutral extension for 1 to 2 weeks. Nonsteroidal anti-inflammatory drugs usually provide symptomatic relief. Injection of the carpal tunnel with hydrocortisone and lidocaine may provide significant but temporary relief. If a definite link has been established between the patient’s occupation and the development of repetitive stress injury, he may have to seek other work. Effective treatment may also require correction of an underlying disorder. When conservative treatment fails, the only alternative is surgical decompression of the nerve by resecting the entire transverse carpal tunnel ligament or by using endoscopic surgical techniques. Neurolysis (freeing of the nerve fibers) may also be necessary.
Special considerations
Patient care for carpal tunnel syndrome includes the following:
❑ Administer mild analgesics as needed. Encourage the patient to use his hands as much as possible. If his dominant hand has been impaired, you may have to help with eating and bathing.
❑ Teach the patient how to apply a splint. Tell him not to make it too tight. Show him how to remove the splint to perform gentle range-of-motion exercises, which should be done daily. Make sure the patient knows how to do these exercises before he’s discharged.
❑ After surgery, monitor vital signs, and regularly check the color, sensation, and motion of the affected hand.
❑ Advise the patient who’s about to be discharged to occasionally exercise his hands in warm water. If the arm is in a sling, tell him to remove the sling several times a day to do exercises for his elbow and shoulder.
❑ Suggest occupational counseling for the patient who has to change jobs because of repetitive stress injury.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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