Abstract
Carpal tunnel syndrome is the most common entrapment neuropathy encountered in clinical practice. It is caused by compression of the median nerve as it passes through the carpal canal at the wrist. The most common causes of compression of the median nerve at this location include flexor tenosynovitis, rheumatoid arthritis, pregnancy, amyloidosis, and other space-occupying lesions that compromise the median nerve as it passes through this closed space. It occurs more commonly in women. This entrapment neuropathy presents as pain, numbness, paresthesias, and associated weakness in the hand and wrist that radiate to the thumb, index finger, middle finger, and radial half of the ring finger. These symptoms may also radiate proximal to the entrapment into the forearm. Untreated, progressive motor deficit and, ultimately, flexion contracture of the affected fingers can result. Symptoms usually begin after repetitive wrist motions or repeated pressure on the wrist, such as resting the wrists on the edge of a computer keyboard. Direct trauma to the median nerve as it enters the carpal tunnel may result in a similar clinical presentation. Recent studies have suggested a higher incidence of abnormalities of connective tissue coding genes in patients suffering from carpal tunnel syndrome when compared with normal controls.
Keywords
carpal tunnel syndrome, entrapment neuropathy, median nerve entrapment, wrist pain, persistent median artery, carpal tunnel injection, ultrasound guided carpal tunnel injection, diagnostic ultrasonography, Phalen test, Tinel sign
ICD-10 CODE G56.00
Keywords
carpal tunnel syndrome, entrapment neuropathy, median nerve entrapment, wrist pain, persistent median artery, carpal tunnel injection, ultrasound guided carpal tunnel injection, diagnostic ultrasonography, Phalen test, Tinel sign
ICD-10 CODE G56.00
The Clinical Syndrome
Carpal tunnel syndrome is the most common entrapment neuropathy encountered in clinical practice. It is caused by compression of the median nerve as it passes through the carpal canal at the wrist. The most common causes of compression of the median nerve at this location include flexor tenosynovitis, rheumatoid arthritis, pregnancy, amyloidosis, and other space-occupying lesions that compromise the median nerve as it passes through this closed space. It occurs more commonly in women. This entrapment neuropathy presents as pain, numbness, paresthesias, and associated weakness in the hand and wrist that radiate to the thumb, index finger, middle finger, and radial half of the ring finger. These symptoms may also radiate proximal to the entrapment into the forearm. Untreated, progressive motor deficit and, ultimately, flexion contracture of the affected fingers can result. Symptoms usually begin after repetitive wrist motions or repeated pressure on the wrist, such as resting the wrists on the edge of a computer keyboard ( Fig. 50.1 , Box 50.1 ). Direct trauma to the median nerve as it enters the carpal tunnel may result in a similar clinical presentation. Recent studies have suggested a higher incidence of abnormalities of connective tissue coding genes in patients suffering from carpal tunnel syndrome when compared with normal controls.
Structural/Anatomic
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Persistent median artery
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Aneurysm
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Lipoma
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Ganglion
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Neuroma
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Acromegaly
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Fracture
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Inflammatory
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Tenosynovitis
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Collagen vascular disease
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Rheumatoid arthritis
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Scleroderma
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Gout
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Crystal deposition disease
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Neuropathic/Ischemic
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Diabetes
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Alcoholism
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Vitamin abnormalities
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Ischemic neuropathies
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Peripheral neuropathies
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Amyloidosis
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Shifts in Fluid Balance
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Pregnancy
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Hypothyroidism
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Obesity
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Kidney failure
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Menopause
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Repetitive Stress Related
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Abnormal hand and wrist position
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Excessive flexion
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Microtrauma
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Vibration
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Signs and Symptoms
Physical findings include tenderness over the median nerve at the wrist. A positive Tinel sign is usually present over the median nerve as it passes beneath the flexor retinaculum ( Fig. 50.2 ). A positive Phalen maneuver is highly suggestive of carpal tunnel syndrome. The Phalen maneuver is performed by having the patient place the wrists in complete unforced flexion for at least 30 seconds ( Fig. 50.3 ). If the median nerve is entrapped at the wrist, this maneuver reproduces the symptoms of carpal tunnel syndrome. Weakness of thumb opposition and wasting of the thenar eminence are often seen in advanced cases of carpal tunnel syndrome; however, because of the complex motion of the thumb, subtle motor deficits can easily be missed ( Fig. 50.4 ). Early in the course of carpal tunnel syndrome, the only physical finding other than tenderness over the median nerve may be the loss of sensation in the foregoing fingers.
