Carpal Tunnel Syndrome

Overview

Definition

Carpal tunnel syndrome is the most common entrapment neuropathy of the upper extremity. The volar surfaces of the carpal bones on the dorsal side and the carpal ligament on the palmar surface form the carpal tunnel. The carpal tunnel is a rigid enclosure through which the median nerve and nine flexor tendons pass. Carpal tunnel syndrome occurs when, for a variety of reasons, the median nerve is compressed within or adjacent to the carpal canal. The prevalence rate is approximately 1 per 1,000 people a year.

Etiology

• Thickening of the transverse carpal ligament or synovial sheath hypertrophy causes median nerve compression
• Acromegaly
• Idiopathic causes
• Repetitive motion, repetitive minor trauma
• Trauma to area, Colles' fracture
• Infections—Lyme disease, rubella
• Retention of fluid in the soft tissue of the wrist may cause median nerve compression during pregnancy or menopause
• Palmar mass—ganglion, calcification, uric acid crystals, hypertrophic fat
• Carpal canal mass—neurofibroma, neurilemoma
• Dislocation of carpal bones

Risk Factors

• Women > men (3 to 6:1)
• Age—40 to 60 years
• Caffeine
• Tobacco
• Alcohol—especially former abuse

Signs and Symptoms

Paresthesia—80% of patients:

• Burning
• Prickling
• Tingling—in thenar aspect; aggravated by grasping from a flexed position or by repetitive rotary or repetitive flexion-extension movements
• Sensory loss/numbness—usually with gradual onset
• Cold intolerance
• "Volar hot dog" sign—swelling on the ulnar side of the palmaris longus tendon
• Phalen's sign
• Tinel's sign

Pain:

• Usually bilateral
• Worse at night, after strenuous activity
• Appears in thumb, index, and long fingers, and the radial half of the ring finger
• May radiate into forearm
• Hand weakness, clumsiness
• Symptoms improve with hand shaking or motion restriction

Differential Diagnosis

• Pregnancy
• Myxedema
• Turberculous wrist
• Gout
• Amyloidosis
• Myeloma
• Cervical disk syndrome
• Brachial plexus lesion
• Arthritis (osteo or rheumatoid)

Diagnosis

Physical Examination

Physical examination will reveal loss of sensibility in thumb and all or some of the digits. There may be weakness on abduction or opposition of the thumb. In serious cases the thenar muscle may be damaged to the point of atrophy.

Laboratory Tests

• Sedimentation rate
• Thyroid function studies
• Rheumatoid factor
• Uric acid

Pathological Findings

• Median nerve with momentary obliteration of vascular markings—indicates mild compression
• Median nerve with appearance of an isthmus and both proximal and distal bulging masses—indicates severe compression
• Prolonged nerve conduction across the carpal tunnel

Imaging

• Magnetic resonance imaging—may define cause
• X ray or CT scan—reveals heterotophic calcification

Other Diagnostic Procedures

• Phalen's test—forearms are vertical while the wrists are fully flexed for 60 seconds; paresthesia or numbness are positive for carpal tunnel syndrome; sensitivity 76%, specificity 80%
• Tinel's test—median nerve at the volar crease of the wrist is repeatedly tapped; paresthesia or pain are positive; sensitivity 64%, specificity 55%
• Venous tourniquet at 60 mm Hg causes tingle
• Nerve conduction study—shows presence and extent of peripheral nerve pathology; sensitivity 90%; uncomfortable, expensive, technically demanding
• Electromyography (EMG)—gold standard; needle electrode is inserted in muscle; reveals motor or sensory latency and the location of the nerve compression; abnormal 85% of cases

Treatment Options

Treatment Strategy

• Splinting wrist in slight dorsiflexion—full time for three to four weeks then slowly reduce to nighttime only
• Treat underlying metabolic disorder
• Weight reduction, if needed

Drug Therapies

• Nonsteroidal anti-inflammatory drugs—relieve symptoms; ibuprofen 400 mg tid; side effects—gastrointestinal
• Corticosteroid (e.g., 20 to 40 mg prednisolone) mixed with 1% lidocaine—inject into the tendon sheaths of the carpal tunnel canal to decrease synovitis and swelling, carefully avoiding both the median and ulnar nerves; two weeks' response time, relapse time—18 months; after three injections consider surgery
• Potassium-sparing diuretics, if needed
• Avoidance of habitual repetitive hand motions

Surgical Procedures

• For symptoms persisting beyond three months, for thenar atrophy, and for extremely prolonged sensory or motor latencies from nerve conduction or EMG tests; incision of the transverse carpal ligament at the wrist allows for medial nerve decompression; aids regeneration of the compressed sensory and motor fibers; improves thumb muscle strength and sensation in other digits; complete relief 95% of cases
• Endoscopic surgery—smaller incision, less postoperative pain, quicker recuperation, but limited visibility during procedure has inherent disadvantages

Complementary and Alternative Therapies

Many cases will respond to vitamin B₆ supplementation with partial to full recovery. It may take up to three months for the full effectiveness. Homeopathic treatment, especially arnica gel topically, and contrast hydrotherapy can be useful adjunctive therapies.

Nutrition

• Vitamin B₆ (50 to 200 mg/day) may be deficient, up to 85% of patients improve in pain relief and increased function. Pyridoxal phosphate supplementation should reduce risk of sensory neuropathy with doses of 200 mg/day of other forms of B₆.
• B-complex to prevent imbalance of other B vitamins and for optimum functioning of B₆ pathways.
• Essential fatty acids (1,500 to 3,000 mg/day) for at least one month; anti-inflammatory and reduce symptoms
• Modify diet to reduce or eliminate saturated fats and fried foods, which increase inflammation.
• Curcumin (250 to 500 mg), and bromelain (250 to 500 mg), both between meals. Anti-inflammatory without the side effects of cortisone treatments. May also reduce post operative edema, swelling, and pain.
• Lipoic acid (100 mg bid) is an antioxidant and anti-inflammatory.

Herbs

Herbs may be used as dried extracts (pills, capsules, or tablets), teas, or tinctures (alcohol extraction, unless otherwise noted). Dose for teas is 1 heaping tsp. herb/cup water steeped for 10 minutes (roots need 20 minutes). Antispasmodic and diuretic herbs may help symptoms by relaxing muscle spasm and decreasing swelling.

• Cramp bark (Viburnum opulus): spasmolytic
• St. John's wort (Hypericum perforatum): anti-inflammatory, historically used specifically for nerve pain
• Wild yam (Dioscorea villosa): anti-inflammatory, anti-spasmodic

A combination of the above herbs, equal parts, may decrease inflammation, provide some pain relief, and enhance healing. Dose is 1 to 3 cups of tea/day or 30 drops tincture tid.

Homeopathy

An experienced homeopath would consider an individual's constitutional type to prescribe a more specific remedy and potency. Some of the most common acute remedies are listed below. Acute dose is three to five pellets of 12X to 30C every one to four hours until symptoms resolve.

• Apis mellifica for joints that are red, hot, swollen, especially with irritability
• Arnica montana qid, for a bruised, beat-up feeling, soreness, achy muscles after trauma or overuse; may be especially effective if arnica gel or cream is used topically
• Guaiacum for carpal tunnel syndrome that is improved by cold applications

Physical Medicine

Contrast hydrotherapy: Alternating hot and cold applications brings nutrients to the site and diffuses metabolic waste from inflammation. The overall effect is decreased inflammation, pain relief, and enhanced healing. Immerse the wrists fully. Alternate three minutes hot with one minute cold and repeat three times. This is one set. Do two to three sets/day. Some relief of symptoms may be achieved by washing hands in hot water and rinsing them in cold throughout the day.

Acupuncture

May provide pain relief and decrease inflammation

Massage

May help symptomatically and preventatively, especially with rosemary and/or St. John's wort oil.

Patient Monitoring

Evaluation of treatment during use of splints and corticosteroids needs to be ongoing. Patient may need to be referred for surgery. Without complication, a single follow-up visit is all that is required following surgery.

Other Considerations

Prevention

Avoid repetitive motion for long periods of time.

Complications/Sequelae

Recurrent symptoms may result from any of the following.

• Damaged median nerve from injection of corticosteroids directly into the nerve
• Compression resulting from perineural fibrosis, tenosynovitis, or prior trauma to the palmar cutaneous branch of the median nerve
• Incomplete neurolysis
• Incomplete lesions of the median nerve between the wrist and the axilla may result in causalgia (severe burning pain)

Prognosis

Most patients' symptoms resolve within several months. If not treated, carpal tunnel syndrome in advanced stages can become quite serious, involving sensory deficit, muscle atrophy, and permanent loss of function.

Pregnancy

While hand symptoms are common during pregnancy and the median nerve is at greater risk for compression, as few as 2.3% women have carpal tunnel syndrome. Others more likely have median and ulnar nerve traction or peripheral edema. Corticosteroid injections reduce symptoms well during pregnancy. For most women, the symptoms will completely resolve post partum.

References

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