Carpal tunnel syndrome (CTS) is a collection of characteristic symptoms and signs that occurs following compression of the median nerve within the carpal tunnel. Usual symptoms include numbness, paresthesias, and pain in the median nerve distribution. These symptoms may or may not be accompanied by objective changes in sensation and strength of median-innervated structures in the hand.
See image below.
The hands of an 80-year-old woman with a several-year history of numbness and weakness are shown in this photo. Note severe thenar muscle (abductor pollicis brevis, opponens pollicis) wasting of the right hand, with preservation of hypothenar eminence.
including electromyography (EMG) and nerve conductions studies (NCS), are the first-line investigations in suggested carpal tunnel syndrome (CTS).
Abnormalities on electrophysiologic testing, in association with specific symptoms and signs, are considered the criterion standard for CTS diagnosis. In addition, other neurologic diagnoses can be excluded with these test results.
Electrophysiologic testing also can provide an accurate assessment of how severe the damage to the nerve is, thereby directing management and providing objective criteria for the determination of prognosis.
Many clinical neurophysiology laboratories are now using ultrasonography as an adjunct to electrodiagnostic studies. Ultrasonography potentially can identify space-occupying lesions in and around the median nerve, confirm abnormalities in the median nerve (eg, increased cross-sectional area) that can be diagnostic of CTS, and help to guide steroid injections into the carpal tunnel.
Magnetic resonance imaging (MRI) of the carpal tunnel is particularly useful preoperatively if a space-occupying lesion in the carpal tunnel is suggested.
Given that CTS is associated with low aerobic fitness and increased body mass index (BMI), it makes some inherent sense to provide the patient with an aerobic fitness and weight-loss program. Stationary biking, cycling, or any other exercise that puts strain on the wrists probably should be avoided. The use of modalities (in particular therapeutic ultrasound) may provide short-term relief in some patients.
Most individuals with mild to moderate CTS (according to electrophysiologic data) respond to conservative management, usually consisting of splinting the wrist at nighttime for a minimum of 3 weeks.
Steroid injection into the carpal tunnel has been shown to be of long-term benefit and can be tried if more conservative treatments have failed.
Patients whose condition does not improve following conservative treatment and patients who initially are in the severe CTS category should be considered for surgery.
Surgical release of the transverse ligament provides high initial success rates (greater than 90%), with low rates of complication; however, it has been suggested that the long-term success rate may be much lower than previously thought (approximately 60% at 5 y). Success rates also are considerably lower for individuals with normal electrophysiologic studies.
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