CTS most often occurs after age 30 and women are affected three times as often as men.⁴ Repetitive strain injury (RSI) from light duty work as a cause of CTS is not well supported by the current literature.⁵ However, a study of 501 participants, 156 of whom were diagnosed with CTS, showed the following risk factors: repetitive activities with a flexed or extended wrist, hysterectomy without oophorectomy, and menopausal women who had their last menstrual period 6 to 12 months earlier.⁶ Others report increased the incidence of CTS due to pregnancy, hypothyroidism, diabetes, and recent menopause.⁷

Diagnostic Considerations

There is no single reference standard for diagnosis of the syndrome; a combination of symptoms, signs, and tests should be used to characterize the disorder.¹

History

CTS typically has an insidious onset of intermittent tingling or numbness, often bilaterally, of the first three fingers and the lateral one half of the fourth digit. Symptoms are frequently worse at night, often waking the patient. As the condition progresses, loss of fine motor skills and loss of grip strength with “things slipping from my fingers” are commonly reported. Relief is gained from shaking the affected hand or hands. Katz and Stirrat ⁸ developed a self-administered hand diagram test that has an 80% sensitivity and a 90% specificity for CTS. Loss of finger dexterity and atrophy are late complaints.

Physical Examination

Examination may show decreased sensation over the distribution of the median nerve to sharp, light touch and vibration (128-Hz tuning fork). Surprisingly, many patients are not able to localize the symptoms to the median distribution and feel that the whole hand is involved, which may be due to autonomic nerve involvement. Tingling in the distribution of the median nerve produced by tapping on the wrist crease (positive Tinel’s sign), tingling in the distribution of the median nerve produced by holding the wrist in forced flexion for 60 to 90 seconds (Phalen’s test), or tingling produced by forcibly extending the wrist and applying pressure over the median nerve (reverse Phalen’s test) are signs of CTS. Early on, the perceived loss of strength may be due to loss of sensory feedback, not loss of strength. Manual muscle tests may elicit weakness of the LOAF muscles (muscles innervated by the median nerve in the hand; Lubricals first and second, Opponens pollicus, Abductor pollicus, Flexor pollicis brevis). As CTS advances, atrophy of the thenar eminence and weakness of the thumb abductor muscle may develop.

Other Diagnostic Tests

The carpal compression test, when the examiner exerts direct compression with the thumbs over the patient’s carpal tunnel for 30 seconds and reproduces the symptoms, was reported as having 89% sensitivity and 96% specificity when performed with the Durkan guage.⁹ Other studies have not reproduced these findings but have reported “Tinel’s, Phalen’s, Reverse Phalen’s, and carpal tunnel compression tests are more sensitive, as well as being specific tests for the diagnosis of tenosynovitis of the flexor muscles of the hand, rather than being specific tests for CTS.”^34,³⁵ Weakness of the thumb abductor muscle is a strong indication to order neurophysiologic testing (nerve conduction studies [NCS] and/or electromyography). In CTS, NCS may show motor and sensory latencies across the wrist.

Magnetic resonance imaging (MRI) and high-definition ultrasound imaging can measure the dimensions of the carpal tunnel and size of the median nerve, but these tests are expensive and not needed in uncomplicated CTS.

Differential Diagnosis

When the clinical picture is not clear, other sources of paresthesia should be considered, such as compression of the brachial plexus in the thoracic outlet, impingement of the median nerve under the pronator teres muscle, entrapment of either the radial or ulnar nerves. The initial presentation of complex regional pain syndrome (reflex sympathetic dystrophy) may appear to be CTS.

Therapeutic Considerations

Many patients report spontaneous recovery from CTS. CTS from pregnancy most often is self-resolving. The waxing and waning symptoms of CTS can give a false sense of success from conservative treatment. The cost of conservative care in persistent CTS may be greater than a carpal tunnel release when performed as an office procedure.¹¹ In cases of progressive neurologic deficit and pain, an open release procedure may be the best choice of treatment.³⁶ In The Netherlands, only open procedures are compensated by the state plan owing to their high rate of success and low rate of complications. Unless the surgeon has good skills, the more expensive endoscopic procedures have poorer outcomes.¹⁰

Physical Medicine

In 1993, Sucher ¹⁹ described the treatment of four patients with myofascial release and self-stretching techniques performed three to five times daily. Post-treatment comparison magnetic resonance imaging demonstrated increased dimensions in the carpal tunnel, and nerve conduction studies showed reduction in distal latencies or increase in motor response amplitudes. Nerve and tendon gliding exercise produced no changes in Phalen’s test, Tinel’s test, or NCS but reduced the number of reported surgeries.²⁰

Low-Level Laser Therapy

One small (N=11) randomized double-blind placebo-controlled crossover trial of low-level laser therapy (LLLT) combined with microcurrent transcutaneous electrical nerve stimulation.²¹ Eleven patients with mild to moderate symptoms of CTS who had failed to improve with standard medical or surgical treatment were treated with real or sham local applications of LLLT and microcurrent for 3 to 4 weeks. Following treatment there was significant improvement in scores on the McGill Pain Questionnaire; sensory and motor latency scores with EMG; and Tinel’s and Phalen’s tests but not after sham treatment.

Hydrotherapy

An anecdotal naturopathic treatment to relieve CTS pain is immersing the wrist and hand in hot water for 3 minutes, then immersing in cold water for 30 seconds, repeated three to five times once or twice a day. It is important to ensure that the hot water immersion is deeper than the cold.

Acupuncture

A randomized controlled study comparing prednisolone (20 mg for 2 weeks, then 10 mg for 2 weeks) to eight sessions of acupuncture over 4 weeks showed acupuncture to be effective in symptom control, but acupuncture decreased distal motor latency and prednisolone did not.²²

One acupuncture study with puncture of PC-7 and PC-6 on the affected side demonstrated a positive response in 35 of 36 patients (14 of whom were previously treated unsuccessfully with surgery).²³

Erognomics

There is insufficient epidemiologic evidence that computer work causes CTS.⁴ Other studies have not demonstrated that work practices (other than high-force work, like that done by meat packers) has a direct influence on CTS.²⁴

Nutrition

Vitamin B Supplementation

The increased incidence of CTS since its initial description by Phalen in 1950 parallels the increased presence of pyridoxine antimetabolites (hydrazine dyes, isoniazid, hydralazine, dopamine, penicillamine, and oral contraceptives) in the environment as well as the intake of excessive protein.

Ellis and coworkers ²⁵^–²⁷ demonstrated the efficacy of vitamin B₆ supplementation for CTS with 50 mg initially and increased to 200 to 300 mg. Even greater effect was seen when vitamins B₆ and B₂ were given together, possibly owing to riboflavin-dependent enzymes, which convert pyridoxine to pyridoxal 5’-phosphate. Two randomized controlled trials suggest that vitamin B₆ is no better than placebo; however, given its safety profile, vitamin B₆ can be considered in the treatment of CTS.^28,²⁹ Failure of vitamin B₆ supplementation to relieve CTS could be due to a lack of riboflavin or a genetic defect that does not allow sufficient levels of vitamin B₆ to be converted to the active P5P form.