eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics
Carpal Tunnel Syndrome
Updated: Jul 15, 2008
Introduction
Background
Carpal tunnel syndrome (CTS) is a compressive neuropathy of the median nerve at the wrist. The carpal tunnel is located at the base of the palm and is bounded on 3 sides by carpal bones and anteriorly by the transverse carpal ligament. Inside run the median nerve, flexor tendons, and their synovial sheaths.
Pathophysiology
CTS is caused predominantly by compression of the median nerve at the wrist because of hypertrophy or edema of the flexor synovium. Pain is thought to be secondary to nerve ischemia rather than direct physical damage of the nerve.
Frequency
United States
CTS is the most frequently encountered peripheral compressive neuropathy. The estimated lifetime risk of acquiring CTS is 10%, the annual incidence is 0.1% among adults, and overall prevalence of CTS is 2.7%.
Mortality/Morbidity
Early in the course of CTS, the neurologic findings are reversible. If untreated, CTS can result in thenar atrophy, chronic hand weakness, and numbness in the median nerve distribution of the hand.
Sex
CTS is more prevalent in females than in males.
Age
CTS is most common in middle-aged persons.
Clinical
History
Patients typically complain of an intermittent "pins-and-needles" paresthesia in the median nerve distribution of the hand. Pain is generally worse at night than during the day. Patients may awaken with a burning pain or tingling that may be relieved with shaking their hands. Classic CTS is associated with symptoms that affect at least 2 of the first through third digits; symptoms affecting the fourth and fifth digits, wrist pain, and radiation of pain proximal to the wrist may also occur, but classic CTS is not associated with symptoms on the palm or dorsum of the hand.
Symptoms of probable CTS are the same as classic CTS except palmar symptoms may be present, unless confined solely to the ulnar aspect. Possible CTS involves symptoms in at least one of the first 3 digits. The sensitivity of classic or probable CTS symptoms for diagnosing CTS is 80%. CTS is unlikely if no symptoms are present in any of the first 3 digits.
- Symptoms are most often bilateral, insidious in onset, and progressive in nature.
- With advanced nerve compression, an aching sensation is persistent and static and may radiate to the forearm and elbow.
- Inquire with regard to repetitive strain risk, eg, waitperson, assembly packing, computer keyboard work, playing a musical instrument, craftwork.
- Determine if there has been any significant trauma.
- Inquire with regard presence of any other predisposing factors listed below under causes.
Physical
- Weakness of resisted thumb abduction (ie, movement of the thumb at right angles to the palm) is helpful in establishing the electrodiagnosis of CTS.
- Sensory hypalgesia as demonstrated by diminished ability to perceive painful stimuli applied along the palmar aspect of the index finger when compared with the ipsilateral little finger also is associated with the electrodiagnosis of CTS.
- Hyperflexion of the wrist for 60 seconds may elicit paresthesia in the median nerve distribution (ie, Phalen sign). A recent review showed the average sensitivity and specificity of the Phalen sign to be 68% and 73%, respectively.
- Tapping the volar wrist over the median nerve (ie, Tinel sign) may produce paresthesia in the median distribution of the hand. Pooled data show the sensitivity and specificity of the Tinel sign to be 50% and 77%, respectively.
- Shaking or flicking one's hands for relief during maximal symptoms (ie, Flick sign) has been shown to have a sensitivity of 47% and specificity of 62%.
- The loss of 2-point discrimination in the median nerve distribution or abductor pollicis brevis atrophy has a high specificity (>90%) but low sensitivity (<25%).
Causes
- Inflammation of the flexor tendon sheath caused by activities involving repetitive wrist flexion (eg, assembly packing, computer keyboard work, playing a musical instrument, craftwork)
- Edema from trauma of any type (eg, fractures), which can compress the median nerve
- Compression of the median nerve from pregnancy or oral contraceptive-related edema
- Strong association between being overweight or obese and the presence of CTS
- Acromegaly
- Rheumatoid arthritis
- Gout or pseudogout
- Tuberculosis
- Renal failure and hemodialysis
- Hypothyroidism
- Amyloidosis
- Has been associated with diabetes mellitus
More on Carpal Tunnel Syndrome |
Overview: Carpal Tunnel Syndrome |
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| Treatment & Medication: Carpal Tunnel Syndrome |
| Follow-up: Carpal Tunnel Syndrome |
| References |
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References
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Further Reading
Keywords
CTS, median nerve compression at the wrist, carpal tunnel syndrome, compressive neuropathy, median nerve, peripheral compressive neuropathy, hand weakness, numbness in the hand, thenar atrophy, hand pain, wrist pain
Overview: Carpal Tunnel Syndrome