CARPAL TUNNEL SYNDROME from www.emedicine.com

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

Carpal tunnel syndrome (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.

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 carpal tunnel syndrome (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.⁵
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.⁵

• 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, such as waitperson, assembly packing, computer keyboard work, playing a musical instrument, or craftwork.
• Determine if any significant trauma has occurred.
• Inquire with regard to 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 determining which patients will have an electrodiagnosis of CTS.⁶
• 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.⁶
• Hyperflexion of the wrist for 60 seconds may elicit paresthesia in the median nerve distribution (ie, Phalen sign). A literature review showed the average sensitivity and specificity of the Phalen sign to be 68% and 73%, respectively.⁷
• 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.⁷
• 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%.⁷
• 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%).⁷

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 pregnancy⁸  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

Differential Diagnoses

Tendonitis
Tenosynovitis

Other Problems to Be Considered

Compressive neuropathies of the nerve roots and brachial plexus
Proximal median neuropathy
Polyneuropathy

Treatment

Emergency Department Care

• The mainstay of treatment for carpal tunnel syndrome (CTS) is rest, wrist immobilization with a splint, and nonsteroidal anti-inflammatory drugs (NSAIDs). Corticosteroid injections, oral steroids, and diuretics are other treatment modalities that have been used. 
  • A volar splint should be placed in neutral position because flexion and extension of the wrist increases carpal intracanal pressure. Splinting has been shown to have a statistically significant decrease in symptoms compared with controls. Studies comparing nocturnal only splinting to full-time splinting have not revealed a clear difference, although the studies may have been underpowered.^16,17  
  • No data support that NSAIDs are superior to placebo in the treatment of CTS.¹⁷ However, in absence of contraindications, a trial of NSAIDs may be appropriate.
  • Oral steroids have been shown to have an advantage in treating CTS over placebo. The benefit appears short lived, and the studies do not assess the long-term effectiveness or complications of oral steroids used in treating CTS.^16,17
  • Although not typically performed in the emergency department, corticosteroid injections have been shown to have a statistically significant benefit in CTS at 1 month compared with placebo. The effects of corticosteroid injection appear to be time limited, and the benefit beyond 1 month is unclear. Two steroid injections do not appear to add significant clinical benefit to one injection.¹⁸ Local injections have been shown to be superior to systemic corticosteroids.¹⁶ Steroid injection combined with splinting has been shown to be superior to splinting alone.¹⁹  
  • Diuretics have not been shown to be superior to placebo in the treatment of CTS.¹⁷
• Surgery
  • Definitive therapy consists of surgical release of the transverse carpal ligament.
  • The surgical approach may be open or endoscopic. Both approaches have similar efficacy. A randomized controlled trial showed that patients who underwent endoscopic surgery for carpal tunnel syndrome had less postoperative pain than patients who underwent open surgery; however, the difference was small.²⁰  The authors of this study extended the follow-up period to 5 years, and it demonstrated an equivalent improvement in CTS symptoms between an open and an endoscopic carpal tunnel release.²¹ An article in the Cochrane Database of Systematic Reviews states that endoscopic surgery allows an earlier return to work and fewer wound problems, but possible disadvantages may be higher complication rates and cost.²²
  • Surgery for CTS has a long-term success rate of greater than 75%.²³

Consultations

Referral to a hand specialist (plastic surgeon or orthopedic surgeon) for follow-up care is recommended.

Medication

The goal of therapy is to reduce inflammation and prevent complications.

Nonsteroidal anti-inflammatory agents

Most commonly are used for the relief of mild-to-moderate pain. Although the effects of NSAIDs in the treatment of pain tend to be patient specific, ibuprofen usually is the DOC for the initial therapy. Other options include flurbiprofen, ketoprofen, and naproxen.

Flurbiprofen (Ansaid)

May inhibit cyclo-oxygenase enzyme, which in turn inhibits prostaglandin biosynthesis. These effects may result in analgesic, antipyretic, and anti-inflammatory activities.

• Dosing
• Interactions
• Contraindications
• Precautions

Adult

200-300 mg/d PO divided bid/qid

Pediatric

Not established

• Dosing
• Interactions
• Contraindications
• Precautions

Coadministration with aspirin increases risk of inducing serious NSAID-related adverse effects; probenecid may increase concentrations and, possibly, toxicity of NSAIDs; may decrease effect of hydralazine, captopril, and beta-blockers; may decrease diuretic effects of furosemide and thiazides; may increase PT when taking anticoagulants (instruct patients to watch for signs of bleeding); may increase risk of methotrexate toxicity; phenytoin levels may be increased when administered concurrently

• Dosing
• Interactions
• Contraindications
• Precautions

Documented hypersensitivity

• Dosing
• Interactions
• Contraindications
• Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Acute renal insufficiency, interstitial nephritis, hyperkalemia, hyponatremia, and renal papillary necrosis may occur; patients with preexisting renal disease or compromised renal perfusion, risk acute renal failure; leukopenia occurs rarely, is transient, and usually returns to normal during therapy; persistent leukopenia, granulocytopenia, or thrombocytopenia warrants further evaluation and may require discontinuation of drug

Ketoprofen (Actron, Orudis, Oruvail)

For relief of mild to moderate pain and inflammation. Small dosages initially are indicated in small and elderly patients and in those with renal or liver disease.
Doses over 75 mg do not increase therapeutic effects. Administer high doses with caution and closely observe patient for response.

• Dosing
• Interactions
• Contraindications
• Precautions

Adult

25-50 mg PO q6-8h prn; not to exceed 300 mg/d

Pediatric

<3 months: Not established
3 months to 12 years: 0.1-1 mg/kg PO q6-8h
>12 years: Administer as in adults

• Dosing
• Interactions
• Contraindications
• Precautions

Coadministration with aspirin increases risk of inducing serious NSAID-related adverse effects; probenecid may increase concentrations and, possibly, toxicity of NSAIDs; may decrease effect of hydralazine, captopril, and beta-blockers; may decrease diuretic effects of furosemide and thiazides; may increase PT when taking anticoagulants (instruct patients to watch for signs of bleeding); may increase risk of methotrexate toxicity; phenytoin levels may be increased when administered concurrently

• Dosing
• Interactions
• Contraindications
• Precautions

Documented hypersensitivity

• Dosing
• Interactions
• Contraindications
• Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Caution in congestive heart failure, hypertension, and decreased renal and hepatic function; caution in coagulation abnormalities or during anticoagulant therapy

Ibuprofen (Ibuprin, Advil, Motrin)

Usually the DOC for the treatment of mild-to-moderate pain if no contraindications exist.
Inhibits inflammatory reactions and pain, probably by decreasing the activity of cyclooxygenase enzyme, which results in the inhibition of prostaglandin synthesis.
Taking medication with at least 4 oz of water may minimize adverse effects.

• Dosing
• Interactions
• Contraindications
• Precautions

Adult

400 mg PO q4-6h; or 600 mg PO q6h; or 800 mg PO q8h; not to exceed 2400 mg/d

Pediatric

<6 months: Not established
6 months to 12 years: 20-40 mg/kg/d PO divided tid or qid
>12 years: Administer as in adults

• Dosing
• Interactions
• Contraindications
• Precautions

Coadministration with aspirin increases risk of inducing serious NSAID-related adverse effects; probenecid may increase concentrations and, possibly, toxicity of NSAIDs; may decrease effect of hydralazine, captopril, and beta-blockers; may decrease diuretic effects of furosemide and thiazides; monitor PT closely (instruct patients to watch for signs of bleeding); may increase risk of methotrexate toxicity; phenytoin levels may be increased when administered concurrently

• Dosing
• Interactions
• Contraindications
• Precautions

Documented hypersensitivity; peptic ulcer disease, recent GI bleeding or perforation, renal insufficiency, or high risk of bleeding

• Dosing
• Interactions
• Contraindications
• Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Caution in congestive heart failure, hypertension, and decreased renal and hepatic function; caution in anticoagulation abnormalities or during anticoagulant therapy

Naproxen (Anaprox, Naprelan, Naprosyn, Aleve)

Used for the relief of mild-to-moderate pain; inhibits inflammatory reactions and pain by decreasing activity of cyclooxygenase enzyme, which results in a decrease of prostaglandin synthesis. Inexpensive and effective.

• Dosing
• Interactions
• Contraindications
• Precautions

Adult

250 mg PO q6-8h; or 500 mg PO q12h; not to exceed 1 g/d

Pediatric

<2 years: Not established
>2 years: 2.5 mg/kg/dose PO; not to exceed 10 mg/kg/d

Follow-up

Further Outpatient Care

• Perform EMG and nerve conduction studies to help confirm diagnosis of carpal tunnel syndrome.

Complications

• Chronic hand pain
• Chronic hand weakness and numbness
• Chronic disability

Prognosis

• Prognosis is excellent with definitive therapy.
• CTS during pregnancy seems to be less severe than idiopathic CTS and has milder course with fewer cases requiring surgical treatment.
• Risks factors for poorer-than-average prognosis include the following:
  • Advanced disease
  • Atypical symptoms (normal nerve conduction studies, symptoms in fifth digit)
  • Longer symptom duration
  • Older age
  • Coexisting disease (diabetes, other peripheral neuropathy)
  • Heavy manual occupation
• Despite treatment, some patients may have residual fingertip numbness.

Patient Education

• For excellent patient education resources, visit eMedicine's Hand, Wrist, Elbow, and Shoulder Center and Arthritis Center. Also, see eMedicine's patient education article Carpal Tunnel Syndrome.

Miscellaneous

Medicolegal Pitfalls

• Median nerve injury following steroid injection has been reported.

Carpal tunnel syndrome

A painful progressive condition caused by compression of a key nerve in the wrist. Carpal tunnel syndrome occurs when the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. The median nerve controls sensations to the palm side of the thumb and fingers (although not the little finger), as well as impulses to some small muscles in the hand that allow the fingers and thumb to move. The carpal tunnel – a narrow, rigid passageway of ligament and bones at the base of the hand – houses the median nerve and tendons. Sometimes, thickening from irritated tendons or other swelling narrows the tunnel and causes the median nerve to be compressed. The result may be pain, weakness, or numbness in the hand and wrist, radiating up the arm. Although painful sensations may indicate other conditions, carpal tunnel syndrome is the most common and widely known of the entrapment neuropathies in which the body's peripheral nerves are compressed or traumatized.


What are the symptoms of carpal tunnel syndrome?

Symptoms usually start gradually, with frequent burning, tingling, or itching numbness in the palm of the hand and the fingers, especially the thumb and the index and middle fingers. Some carpal tunnel sufferers say their fingers feel useless and swollen, even though little or no swelling is apparent. The symptoms often first appear in one or both hands during the night, since many people sleep with flexed wrists. A person with carpal tunnel syndrome may wake up feeling the need to "shake out" the hand or wrist. As symptoms worsen, people might feel tingling during the day. Decreased grip strength may make it difficult to form a fist, grasp small objects, or perform other manual tasks. In chronic and/or untreated cases, the muscles at the base of the thumb may waste away. Some people are unable to tell between hot and cold by touch. 



What are the causes of carpal tunnel syndrome?

Carpal tunnel syndrome is often the result of a combination of factors that increase pressure on the median nerve and tendons in the carpal tunnel, rather than a problem with the nerve itself. Most likely the disorder is due to a congenital predisposition – the carpal tunnel is simply smaller in some people than in others. Other contributing factors include trauma or injury to the wrist that cause swelling, such as sprain or fracture; overactivity of the pituitary gland; hypothyroidism; rheumatoid arthritis; mechanical problems in the wrist joint; work stress; repeated use of vibrating hand tools; fluid retention during pregnancy or menopause; or the development of a cyst or tumor in the canal. In some cases no cause can be identified.

There is little clinical data to prove whether repetitive and forceful movements of the hand and wrist during work or leisure activities can cause carpal tunnel syndrome. Repeated motions performed in the course of normal work or other daily activities can result in repetitive motion disorders such as bursitis and tendinitis. Writer's cramp – a condition in which a lack of fine motor skill coordination and ache and pressure in the fingers, wrist, or forearm is brought on by repetitive activity – is not a symptom of carpal tunnel syndrome.


Who is at risk of developing carpal tunnel syndrome?

Women are three times more likely than men to develop carpal tunnel syndrome, perhaps because the carpal tunnel itself may be smaller in women than in men. The dominant hand is usually affected first and produces the most severe pain. Persons with diabetes or other metabolic disorders that directly affect the body's nerves and make them more susceptible to compression are also at high risk. Carpal tunnel syndrome usually occurs only in adults.

The risk of developing carpal tunnel syndrome is not confined to people in a single industry or job, but is especially common in those performing assembly line work – manufacturing, sewing, finishing, cleaning, and meat, poultry, or fish packing. In fact, carpal tunnel syndrome is three times more common among assemblers than among data-entry personnel. A 2001 study by the Mayo Clinic found heavy computer use (up to 7 hours a day) did not increase a person's risk of developing carpal tunnel syndrome.

During 1998, an estimated three of every 10,000 workers lost time from work because of carpal tunnel syndrome. Half of these workers missed more than 10 days of work. The average lifetime cost of carpal tunnel syndrome, including medical bills and lost time from work, is estimated to be about $30,000 for each injured worker.


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 wrist is examined for tenderness, swelling, warmth, and discoloration. Each finger should be tested for sensation, and the muscles at the base of the hand should be examined for strength and signs of atrophy. Routine laboratory tests and X-rays can reveal diabetes, arthritis, and fractures.

Physicians can use specific tests to try to produce the symptoms of carpal tunnel syndrome. In the Tinel test, the doctor taps on or presses on the median nerve in the patient's wrist. The test is positive when tingling in the fingers or a resultant shock-like sensation occurs. The Phalen, or wrist-flexion, test involves having the patient hold his or her forearms upright by pointing the fingers down and pressing the backs of the hands together. 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. Doctors may also ask patients to try to make a movement that brings on symptoms.

Often it is necessary to confirm the diagnosis by use of electrodiagnostic tests. 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 can show impaired movement of the median nerve. Magnetic resonance imaging (MRI) can show the anatomy of the wrist but to date has not been especially useful in diagnosing carpal tunnel syndrome.


How is carpal tunnel syndrome treated?

Treatments for carpal tunnel syndrome should begin as early as possible, under a doctor's direction. Underlying causes such as diabetes or arthritis should be treated first. Initial treatment generally involves resting the affected hand and wrist for at least 2 weeks, avoiding activities that may worsen symptoms, and immobilizing the wrist in a splint to avoid further damage from twisting or bending. If there is inflammation, applying cool packs can help reduce swelling.


Non-surgical treatments

Drugs. In special circumstances, various drugs can ease the pain and swelling associated with carpal tunnel syndrome. Nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen, and other nonprescription pain relievers, may ease symptoms that have been present for a short time or have been caused by strenuous activity. Orally administered diuretics ("water pills") can decrease swelling. Corticosteroids (such as prednisone) or the drug lidocaine can be injected directly into the wrist or taken by mouth (in the case of prednisone) to relieve pressure on the median nerve and provide immediate, temporary relief to persons with mild or intermittent symptoms. (Caution: persons with diabetes and those who may be predisposed to diabetes should note that prolonged use of corticosteroids can make it difficult to regulate insulin levels. Corticosterioids should not be taken without a doctor's prescription.) Additionally, some studies show that vitamin B⁶ (pyridoxine) supplements may ease the symptoms of carpal tunnel syndrome.

Exercise. Stretching and strengthening exercises can be helpful in people whose symptoms have abated. These exercises may be supervised by a physical therapist, who is trained to use exercises to treat physical impairments, or an occupational therapist, who is trained in evaluating people with physical impairments and helping them build skills to improve their health and well-being.

Alternative therapies. Acupuncture and chiropractic care have benefited some patients but their effectiveness remains unproved. An exception is yoga, which has been shown to reduce pain and improve grip strength among patients with carpal tunnel syndrome.


Surgery

Carpal tunnel release is one of the most common surgical procedures in the United States. Generally recommended if symptoms last for 6 months, surgery involves severing the band of tissue around the wrist to reduce pressure on the median nerve. Surgery is done under local anesthesia and does not require an overnight hospital stay. Many patients require surgery on both hands. The following are types of carpal tunnel release surgery:

Open release surgery, the traditional procedure used to correct carpal tunnel syndrome, consists of making an incision up to 2 inches in the wrist and then cutting the carpal ligament to enlarge the carpal tunnel. The procedure is generally done under local anesthesia on an outpatient basis, unless there are unusual medical considerations.

Endoscopic surgery may allow faster functional recovery and less postoperative discomfort than traditional open release surgery. The surgeon makes two incisions (about ½" each) in the wrist and palm, inserts a camera attached to a tube (see endoscopes and endoscopy), observes the tissue on a screen, and cuts the carpal ligament (the tissue that holds joints together). This two-portal endoscopic surgery, generally performed under local anesthesia, is effective and minimizes scarring and scar tenderness, if any. One-portal endoscopic surgery for carpal tunnel syndrome is also available.

Although symptoms may be relieved immediately after surgery, full recovery from carpal tunnel surgery can take months. Some patients may have infection, nerve damage, stiffness, and pain at the scar. Occasionally the wrist loses strength because the carpal ligament is cut. Patients should undergo physical therapy after surgery to restore wrist strength. Some patients may need to adjust job duties or even change jobs after recovery from surgery.

Recurrence of carpal tunnel syndrome following treatment is rare. The majority of patients recover completely.


How can carpal tunnel syndrome be prevented?

At the workplace, workers can do on-the-job conditioning, perform stretching exercises, take frequent rest breaks, wear splints to keep wrists straight, and use correct posture and wrist position. Wearing fingerless gloves can help keep hands warm and flexible. Workstations, tools and tool handles, and tasks can be redesigned to enable the worker's wrist to maintain a natural position during work. Jobs can be rotated among workers. Employers can develop programs in ergonomics, the process of adapting workplace conditions and job demands to the capabilities of workers. However, research has not conclusively shown that these workplace changes prevent the occurrence of carpal tunnel syndrome.


What research is being done?

The National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health, is the federal government's leading supporter of biomedical research on neuropathy, including carpal tunnel syndrome. Scientists are studying the chronology of events that occur with carpal tunnel syndrome in order to better understand, treat, and prevent this ailment. By determining distinct biomechanical factors related to pain, such as specific joint angles, motions, force, and progression over time, researchers are finding new ways to limit or prevent carpal tunnel syndrome in the workplace and decrease other costly and disabling occupational illnesses.

Randomized clinical trials are being designed to evaluate the effectiveness of educational interventions in reducing the incidence of carpal tunnel syndrome and upper extremity cumulative trauma disorders. Data to be collected from an NINDS-sponsored clinical study of carpal tunnel syndrome among construction apprentices will provide a better understanding of the specific work factors associated with the disorder, furnish pilot data for planning future projects to study its natural history, and assist in developing strategies to prevent its occurrence among construction and other workers. Other research will discern differences between the relatively new carpal compression test (in which the examiner applies moderate pressure with both thumbs directly on the carpal tunnel and underlying median nerve, at the transverse carpal ligament) and the pressure provocative test (in which a cuff placed at the anterior of the carpal tunnel is inflated, followed by direct pressure on the median nerve) in predicting carpal tunnel syndrome. Scientists are also investigating the use of alternative therapies, such as acupuncture, to prevent and treat this disorder.

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