Lingua/Sprache/Language          -   Last updated 08 May 2008

How is carpal tunnel syndrome diagnosed?

Early diagnosis and treatment are important to avoid permanent damage to the median nerve. A physical examination of the hands, arms, shoulders, and neck can help determine if the patient's complaints are related to daily activities or to an underlying disorder, and can rule out other painful conditions that mimic carpal tunnel syndrome. The differential diagnosis of pathologies of the hand and wrist includes entrapments of the nerve, carpal tunnel syndrome,Guyons'syndrome, cervical radiculopathy, tendon disorders, etc. Physicians can use specific tests to try to produce the symptoms of carpal tunnel syndrome. Loss of two- point discrimination in the median nerve distribution has low sensitivity and high specificity, tests of the patient's ability to perceive degrees of vibratory stimulation and direct pressure on the pulp of the finger in the median nerve distribution are technically demanding and have moderate sensitivity and specificity. In the Tinel test the physician taps the median nerve at the wrist. A tingling response in one or more fingers can toindicate damage to the median nerve. In the Phalen, or wrist-flexion, the patient puts the backs of the hands together and bends the wrists for one minute. Tingling of the fingers can to indicate damage to the median nerve. The presence of carpal tunnel syndrome is suggested if one or more symptoms, such as tingling or increasing numbness, is felt in the fingers within 1 minute. Phalen's test report a range of values for sensitivity and specificity, from 40 to 80 percent. The sensitivity of tinel's sign ranges from 25 to 60 percent, specificity from 67 to 87 percent. The history and physical examination have poor predictive value when the likelihood of carpal tunnel syndrome is low, they are most useful when there is a reasonable clinical suspicion of carpal tunnel syndrome.
Electrodiagnostic examinations (nerve conduction studies and electromyography) and knowledge of the location and type of symptoms permits the most accurate diagnosis of carpal tunnel syndrome.
Both symptoms and electrodiagnostic studies must be interpreted carefully.
Electrodiagnostic studies are most useful for confirm the diagnosis in suspected cases and ruling out neuropathy and other nerve entrapments.
In a nerve conduction study, electrodes are placed on the hand and wrist. Small electric shocks are applied and the speed with which nerves transmit impulses is measured. In electromyography, a fine needle is inserted into a muscle; electrical activity viewed on a screen can determine the severity of damage to the median nerve. Ultrasound imaging and magnetic resonance imaging (MRI) can show the anatomy of the wrist but to date has not been especially useful in diagnosing carpal tunnel syndrome.

TABLE OF CONTENTS

• What is Carpal Tunnel Syndrome?
• What are the symptoms of carpal tunnel syndrome?
• Who is at risk of developing carpal tunnel syndrome?
• What are the causes of carpal tunnel syndrome?
• How is carpal tunnel syndrome diagnosed?
• How can carpal tunnel syndrome be prevented?
• How is carpal tunnel syndrome treated?

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