AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy in the upper extremity. The condition is usually bilateral, although the dominant hand tends to be more severely affected.

Pathophysiology

The median nerve crosses from the distal forearm to the hand through the carpal tunnel. The floor of the carpal tunnel is formed by the carpal bones and the roof by the transverse carpal ligament. Compression of the median nerve by the transverse carpal ligament (flexor retinaculum) can occur.

The palmar cutaneous branch of the median nerve leaves the main trunk 5-8 cm proximal to the wrist crease. It provides sensation to the thenar eminence and does not traverse the carpal tunnel. Loss of sensation over the thenar eminence is not part of CTS but suggests a lesion proximal to the wrist.

Frequency

United States

In Rochester, Minnesota, prevalence was estimated to be 125 per 100,000 during the period from 1976-1980. Most cases are idiopathic.

Other studies estimated the prevalence rates for CTS to be 1-5% in the general population and 5-15% in the industrial setting, but the rate is dependent on how CTS is defined.

Epidemiologic studies have demonstrated that the highest incidence of CTS tends to be in poultry processors and meat packing workers, followed by garment workers and automobile assembly workers.

Race

Findings of the 1988 National Health Interview survey indicate that CTS is 1.8 times more prevalent in whites than nonwhites.

Sex

Women are affected more than men. Phalen's series (1970) included 280 women and 96 men (female-to-male ratio 3:1).

Age

Of the patients in Phalen's series (1970), 58% were adults aged 40-60 years.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

CTS patients describe diffuse, poorly localized aching that can involve the entire hand and forearm.

• Many patients report that the entire hand falls asleep; if they are asked to note whether the little finger is involved, they subsequently note that the little finger is spared.
• Some patients also describe weakness, clumsiness, dry skin, coldness, swelling, and/or color changes in the hand. Nocturnal paresthesias may awaken the patient from sleep.
• Provocative factors: Symptoms are more common during a flexed or extended wrist posture. Discomfort may be provoked by driving or by holding the phone, a book, or a newspaper.
• Alleviating factors: Symptoms are relieved partially by changes in hand posture or shaking the hand.

Physical

Examination may be normal.

• Provocative tests: The Tinel sign, Phalen maneuver, and direct compression test are sometimes useful.
• • Tinel sign: Paresthesias are provoked by tapping over the median nerve at the wrist in 26-73% of patients with CTS and 6-45% of controls.
  • Phalen test: While holding the wrist flexed, paresthesia occurs within 1-2 minutes in 74% of patients with CTS and 25% of controls.
• Motor examination
• • Inspect the hand and check for muscle atrophy.
  • Test the strength of thumb abduction and opposition.
    • Isolating the muscle action of abductor pollicis brevis is difficult, since thumb abduction also may be performed by the abductor pollicis longus (ie, radial nerve).
    • A similar situation occurs with opponens pollicis since thumb opposition also may be produced by a combination of the flexor pollicis brevis (ie, deep head - ulnar nerve) and the flexor pollicis longus (ie, anterior interosseous nerve).
• Sensory examination
• • Two-point discrimination may be affected before pain and temperature sensation.
  • Even in severe cases of CTS, sensation over the thenar area usually is spared, as it is innervated by the palmar cutaneous sensory branch (a median nerve branch that arises proximal to but does not pass through the carpal tunnel).
• Dry skin may be seen on digits I-III.

Causes

• Most cases are idiopathic, but some cases may be caused by excessive and repetitive hand movements.
• • Highly repetitive wrist and finger use is a greater risk factor than forceful hand use.
  • The combination of finger flexion with repetitive wrist motion is probably the most provocative stressor.
  • The classic concept of repetitive motion-induced chronic tenosynovitis resulting in CTS has been questioned.
  • Keyboard data entry has not been established as a cause of CTS.
  • The relationship between carpal canal size and CTS risk remains controversial.
• The following list includes some underlying diseases and conditions associated with CTS:
• • Congenital - Persistent median artery, congenital small carpal tunnel, anomalous muscles (palmaris longus, flexor digitorum sublimis)
  • Connective tissue disease - Rheumatoid arthritis
  • Endocrine - Acromegaly, diabetes, hypothyroidism
  • Infectious/inflammatory - Histoplasmosis, Lyme disease, sarcoid, septic arthritis
  • Miscellaneous - Spasticity, especially with persistent wrist flexion, renal disease, hemodialysis, amyloidosis (familial and acquired), pregnancy, any other condition that increases edema or total body fluid
  • Trauma - Wrist fracture (particularly Colles fracture), hemorrhage (including anticoagulation)
  • Tumors - Ganglion, hemangioma, lipoma, neurofibroma, schwannoma
• Other diagnostic considerations
• • CTS versus C6 radiculopathy
    • The 2 conditions can coexist.
    • C6 radiculopathy usually causes neck and shoulder pain, weakness in C6 innervated muscles, and sensory loss restricted to the thumb.
    • Absence of nocturnal paresthesias and reproduction of the paresthesias with root compression maneuvers help to differentiate these 2 conditions.
  • CTS versus proximal median nerve problem
    • Flexor pollicis longus is innervated by the anterior interosseus nerve.
    • This muscle flexes the distal phalanx of the thumb and is not involved in CTS.
    • Even in severe CTS, sensation over the thenar area is spared, as it is innervated by the palmar cutaneous sensory branch (which arises proximal to and does not pass through the carpal tunnel).
  • CTS versus de Quervain tenosynovitis syndrome
    • Tenosynovitis develops in the abductor pollicis longus and extensor pollicis brevis tendons, which are held in a groove of the radius by a firm segment of the extensor retinaculum.
    • Signs and symptoms include the following: (1) pain in the radial aspect of the wrist and thumb that is aggravated by movement of the wrist and thumb; (2) pain and paresthesias radiating into the thumb, dorsum of the hand, and index finger due to irritation of the radial nerve by severe inflammation; and (3) pain when the thumb is flexed into the palm while the examiner deviates the wrist in the ulnar direction (ie, Finkelstein test).
  • CTS versus median neuropathy at the elbow and brachial plexopathy
    • Both median neuropathy and brachial plexopathy are rare.
    • The following findings may suggest a more proximal involvement of the median nerve: (1) sensory loss or paresthesia over the thenar eminence, in addition to the usual distribution of sensory disturbance in the fingers; (2) weakness of median innervated muscles proximal to the wrist, especially distal thumb flexion (flexor pollicis longus), arm pronation (pronator teres and pronator quadratus), and wrist flexion (flexor carpi radialis).
• Other risk factors for the development of CTS include ergonomic stressors, history of a median mononeuropathy, higher body mass index (BMI), history of diabetes, and rheumatoid arthritis.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Brachial plexopathy
C6 radiculopathy
Cervical disk syndromes
De Quervain tenosynovitis syndrome
Interosseous syndrome
Proximal median neuropathy (eg, at the elbow)

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Blood tests should be ordered if underlying rheumatologic or inflammatory disease or diabetes is suspected; these include fasting blood glucose, erythrocyte sedimentation rate, and rheumatoid factor.

Imaging Studies

• Wrist x-ray may be helpful if an old or recent fracture is suspected.
• Magnetic resonance imaging (MRI) of the cervical spine may be needed if cervical radiculopathy is suspected. Some reports on the usefulness of MRI scan of the wrist have been recorded.
• CT scan of the chest or chest x-ray should be ordered if brachial plexopathy is suspected.

Other Tests

• Electrodiagnosis
• • Distal motor latency: Stimulate the median nerve at the wrist and record at the abductor pollicis brevis muscle. A markedly prolonged distal latency may be measured. However, in over 50% of patients with CTS, distal median motor latency is within the normal limit.
  • Distal sensory latency: Orthodromic or antidromic sensory studies are performed by stimulating or recording the second (index) or third (middle) fingers. Another method is to stimulate or record at the palm (8 cm from the wrist). To increase sensitivity, the following internal comparison can be used:
    • Compare the median and ulnar nerves from palm to wrist at a distance of 8 cm. Distal latency difference of >0.4 millisecond is a significant finding.
    • Compare the median and ulnar nerve distal sensory latencies by stimulating at the ring finger and recording at the wrist for each nerve. A difference of >0.5 millisecond is significant.
    • Compare median and radial nerves by stimulating the thumb and recording at the wrist at a distance of 10 cm. Distal latency difference >0.5 millisecond is a significant finding.
• The benefits of the following diagnostic techniques have yet to be fully established:
• • Carpal tunnel pressure measurements
  • Current perception threshold
  • MRI quantitation of the carpal tunnel
  • Sensory quantitation, including vibrometry
  • Ultrasound of the carpal tunnel
  • Semmes-Weinstein pressure esthesiometer

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

Conservative treatment is usually recommended.

• Wrist splint: A lightweight plastic/Velcro splint in a neutral position that allows semifree finger movement is recommended. Precautions should be taken to prevent a persistently stiff wrist, sometimes called the "frozen wrist" syndrome, that is caused by prolonged immobilization.
• Modify activity: Reduce wrist flexion, extension, rotation, finger flexion, and forceful gripping.
• A local steroid injection may be considered. Local injection may have a distinctive role as a predictor of response to surgical release.
• • Corticosteroids (usually DepoMedrol 40-80 mg) are injected adjacent to the carpal tunnel.
  • Care must be taken not to inject the carpal tunnel, any tendon, or the nerve itself. Such an injection may increase the intracarpal tunnel pressure and cause additional nerve injury.
  • The effect of steroid injections may be seen within a few days and often lasts for several weeks or months.
    • The main disadvantage of this treatment is that the effect is often temporary.
    • Unfortunately, repeated use (more than 2 or 3 injections) is not advised because of the possibility of local tendon damage.
  • Local injection may not be advisable for CTS in the presence of systemic disease, mass lesions (at the wrist), or a major bony deformity. Early surgery may be needed in these cases.
  • Complications include increased median nerve deficit, local infection, reflex sympathetic dystrophy, and tendon rupture.

Surgical Care

• Surgical decompression may be indicated in the following situations:
• • Patient is older than 50 years.
  • Symptoms persist (eg, >10 mo) despite conservative therapy.
  • The distal median neuropathy is severe and associated with axonal loss, with reduced compound motor action potential.
    • Evidence of thenar atrophy and persistent hypesthesia
    • Low median motor and sensory amplitudes from axonal loss seen on nerve conduction studies
    • Evidence of denervation in distal median innervated muscles on electromyography (EMG)
  • Mass lesion is noted (eg, nerve tumor, ganglion cyst).
• Urgent surgery may be needed in acute CTS following local trauma, especially if the wrist and hand are swollen with sensory changes shortly after trauma.
• Open carpal tunnel release was compared with steroid injection in a study reported in 2005. According to the study, surgery resulted in better symptomatic and neurophysiologic outcome but not grip strength in patients with idiopathic carpal tunnel syndrome over a 20-week period.
• Surgical release may provide satisfactory relief in 75-90% of these cases.
• Causes of incomplete relief from surgery include incomplete section of flexor retinaculum, multifactorial hand symptoms, and an incorrect preoperative diagnosis.
• Recurrent postsurgical symptoms after initial success may be caused by perineural fibrosis, progressive tenosynovitis, or recurrent fibrosis of flexor retinaculum.
• New symptom patterns after surgery include joint stiffness, nerve branch injury, reflex sympathetic dystrophy, and infection.
• Endoscopic release: This procedure is currently investigational. It carries an increased risk of injury to the digital branches of the median nerve.

Consultations

If CTS surgery is required, an experienced neurosurgeon, plastic surgeon, or hand surgeon should be consulted.

Diet

No specific diet is indicated for patients with CTS. A low-salt diet may be indicated if fluid retention is a contributing factor.

Activity

Prolonged, repetitive use of the wrist (especially with force) may aggravate this condition.

• Provide an optimal work environment.
• Ergonomic changes in the workplace can be helpful.
• • Work should be placed 10-12 inches in front of the eyes.
  • Elbows should be postured at an angle of 85-100°.
  • Shoulder should be in the vertical position, with abduction no greater than 20°.
  • Wrist should be in the neutral position, without ulnar or radial deviation, with minimal flexion or extension.
  • Environmental conditions such as temperature extremes and vibration should be minimized.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Nonsteroidal anti-inflammatory medications (NSAIDs) frequently are prescribed for this condition; caution patients to watch for the usual adverse effects. Short-term diuretic treatment may be helpful in patients with limb swelling. One study reported better symptomatic relief with short-term, low-dose steroid (20 mg qd x 2 wk, then 10 mg qd x 2 wk).

Drug Category: Nonsteroidal anti-inflammatory drugs (NSAIDs)

These agents have analgesic and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell-membrane functions. Various NSAIDs may be used.

Drug Category: Corticosteroid agents

A recent report suggested that short-term oral steroids may be beneficial in CTS.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• Inpatient care usually is not indicated.

Further Outpatient Care

• Monitor motor and sensory function and subjective symptoms.

In/Out Patient Meds

• NSAIDs may be beneficial.

Prognosis

• For mild cases, conservative treatment is usually adequate.
• Surgical decompression usually produces good results. Patients with advanced thenar muscle atrophy usually do not recover fully after surgical decompression.
• CTS that is caused by or aggravated by an underlying disease (eg, diabetes) has a worse prognosis.

Patient Education

• Modifying occupation or ergonomic conditions (eg, tools) may be beneficial.
• For excellent patient education resources, visit eMedicine's Hand, Wrist, Elbow, and Shoulder Center. Also, see eMedicine's patient education article Carpal Tunnel Syndrome.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Repeated steroid injections may cause tendon rupture.
• Direct injection into the nerve may cause irreversible damage.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Altrocchi PH, Daube JR, Frishberg BM. Practice parameter: carpal tunnel syndrome. Neurology. 1993;43(11):2406-9.
• Campbell WW. Diagnosis and management of common compression and entrapment neuropathies. Neurol Clin. Aug 1997;15(3):549-67. [Medline].
• Chang MH, Chiang HT, Lee SS, et al. Oral drug of choice in carpal tunnel syndrome. Neurology. Aug 1998;51(2):390-3. [Medline].
• Fleckenstein JL, Wolfe GI. MRI vs EMG: which has the upper hand in carpal tunnel syndrome?. Neurology. Jun 11 2002;58(11):1583-4. [Medline].
• Gooch CL, Mitten DJ. Treatment of carpal tunnel syndrome: is there a role for local corticosteroidinjection?. Neurology. Jun 28 2005;64(12):2006-7. [Medline].
• Gross PT, Tolomeo EA. Proximal median neuropathies. Neurol Clin. Aug 1999;17(3):425-45, v. [Medline].
• Hui AC, Wong S, Leung CH, et al. A randomized controlled trial of surgery vs steroid injection for carpal tunnelsyndrome. Neurology. Jun 28 2005;64(12):2074-8. [Medline].
• Levine BP, Jones JA, Burton RI. Nerve entrapments of the upper extremity: A surgical perspective. Neurol Clin. Aug 1999;17(3):549-65, vii. [Medline].
• Morgan G, Wilbourn AJ. Cervical radiculopathy and coexisting distal entrapment neuropathies: double-crush syndromes?. Neurology. Jan 1998;50(1):78-83. [Medline].
• Nuber GW, Assenmacher J, Bowen MK. Neurovascular problems in the forearm, wrist, and hand. Clin Sports Med. Jul 1998;17(3):585-610. [Medline].
• Preston DC, Shefner JM, Rutkove SB. Electrodiagnosis of carpal tunnel syndrome: too many and too few tests. American Academy of Neurology Annual Meeting. 1999;2PC003.
• Preston DC. Distal median neuropathies. Neurol Clin. Aug 1999;17(3):407-24, v. [Medline].
• Verdon ME. Overuse syndromes of the hand and wrist. Prim Care. Jun 1996;23(2):305-19. [Medline].

Article Last Updated: Mar 27, 2007