Carpal Tunnel Syndrome
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- Symptomatic compression neuropathy of the median nerve
- Increased pressure within the carpal tunnel leads to compression of the median nerve and characteristic motor-sensory findings.
- The dorsal aspect of the carpal tunnel is composed of the carpal bones. The transverse carpal ligament defines the palmar boundary:
- The carpal tunnel contains nine flexor tendons and the median nerve.
- Symptoms most commonly affect the dominant hand; >50% of patients will experience bilateral symptoms.
- System(s) affected: musculoskeletal, nervous
Increased incidence during pregnancy (up to 20–45%)
- Predominant age: 40 to 60 years
- Predominant sex: female > male (3:1 to 10:1)
- Two peaks: late 50s (women), late 70s (both genders)
- Incidence up to 276/100,000 has been reported.
- Incidence increases with age.
- 9% in women and 6% in men; 50 cases per 1,000 individuals per year in United States
- 14% in diabetics without neuropathy and 30% in patients with diabetic neuropathy
- Rising prevalence may be the result of increasing lifespan and increasing prevalence of diabetes.
- Most expensive upper extremity musculoskeletal disorder; >$2 billion per year
- Median time lost by U.S. workers with carpal tunnel syndrome (CTS) = 28 days
Etiology and Pathophysiology
- Combination of mechanical trauma, inflammation, increased pressure, and ischemic injury to the median nerve within the carpal tunnel
- Acute CTS caused by rapid and sustained pressure in carpal tunnel, usually secondary to trauma, may require urgent surgical decompression.
- Distal radius fractures and volar lunate dislocations increase risk.
- Chronic CTS divided into four categories:
- Idiopathic: combination of edema and fibrous hypertrophy without inflammation
- Anatomic: persistent median artery, ganglion cyst, infection, space-occupying lesion in carpal tunnel
- Systemic: associated with conditions such as obesity, diabetes, hypothyroidism, rheumatoid arthritis, amyloidosis, scleroderma, renal failure, and drug toxicity
- Exertional: repetitive use of hands and wrists, repeated palmar impact, use of vibratory tools. Repetitive use is an objective cause of CTS.
Unknown; however, a familial type has been reported.
- Prolonged postures in extremes of wrist flexion and extension including activities such as gardening, cycling, or tennis; repetitive exposure to vibration
- Typing is NOT a risk factor.
- Alterations of fluid balance: pregnancy, rheumatoid arthritis, obesity, renal failure, hypothyroidism, congestive heart failure
- CTS is the most common neuropathy in patients with rheumatoid arthritis.
- Neuropathic factors: diabetes, alcoholism, vitamin deficiency, or exposure to toxins
There is no known prevention for CTS. It is recommended to take occasional (e.g., hourly) breaks when doing repetitive work involving hands or if prolonged occupational exposure to vibratory tools.
Commonly Associated Conditions
- Diabetes, obesity; pregnancy; hypothyroidism
- Osteoarthritis of small joints of hand and wrist
- Hyperparathyroidism, hypocalcemia