Median nerve

About: Median nerve is a research topic. Over the lifetime, 6262 publications have been published within this topic receiving 129139 citations.

Carpal tunnel syndrome

Abstract: Carpal tunnel syndrome is the most common peripheral nerve compression syndrome. Compression of the median nerve in the carpal tunnel, disrupts the blood-nerve barrier causing edema, inflammation and fibrosis of its surrounding connective tissues. In the next stage of the syndrome there is a disruption of the myelin coverage of the nerve followed by damage to the axons. Most carpal tunnel syndromes are idiopathic. Other causes include intrinsic factors (which cause pressure within the tunnel), extrinsic factors (which cause pressure from outside the tunnel) and overuse/exertional factors. Patients usually report numbness and pain of the palmar aspect of their 1st, 2nd, 3rd and radial half of their 4th finger, night pain and gradual worsening of their symptoms. At a later stage, weakness and atrophy of the thenar muscles appears. The physical examination may show a decrease in sensibility, positive provocative tests and a decrease in thenar strength. The typical finding in the nerve conduction tests is a prolonged latency period. The conservative treatment for carpal tunnel syndrome includes ergonomic modifications, anti inflammatory medications and splintage and less frequently, special exercise and therapeutic ultrasound. The indications for operative treatment are failure of conservative treatment or severe carpal tunnel syndrome. The purpose of the operation is to relieve the pressure in the carpal tunnel by dissecting the transverse ligament. The operation can be done in an open approach, endoscopic approach or limited invasive approach.

The carpal-tunnel syndrome. Seventeen years' experience in diagnosis and treatment of six hundred fifty-four hands.

Abstract: At the Cleveland Clinic the diagnosis of carpal-tunnel syndrome has been made in 654 hands of 439 patients during the last seventeen years. The typical patient with this syndrome is a middle-aged housewife with numbness and tingling in the thumb and index, long, and ring fingers, which is worse at night and worse after excessive activity of the hands. The sensory disturbances, both objective and subjective, must be directly related to the sensory distribution of the median nerve distal to the wrist; but pain may be referred proximal to the wrist as high as the shoulder. There is usually a positive Tinel sign over the median nerve at the wrist, and the wrist-flexion test I described is also usually positive. About half of the patients also have some degree of thenar atrophy. If steroid injections into the carpal tunnel give only transient relief, treatment should be by complete section of the transverse carpal ligament. This procedure will almost always relieve the patient's pain and numbness in the hand, and in many cases will also cure the paralysis of the thenar muscles, which may be present.

The carpal tunnel syndrome: localization of conduction abnormalities within the distal segment of the median nerve.

Abstract: Palmar stimulation was used to assess median nerve conduction across the carpal tunnel in 61 control patients and 105 patients with the carpal tunnel syndrome. With serial stimulation from midpalm to distal forearm the sensory axons normally showed a predictable latency change of 0.16 to 0.21 ms/cm as the stimulus site was moved proximally in 1 cm increments. In 47 (52 per cent) of 91 affected nerves tested serially, there was a sharply localized latency increase across a 1 cm segment, most commonly 2 to 4 cm distally to the origin of the transverse carpal ligament. In these hands, the focal latency change across the affected 1 cm segment (mean +/- SD: 0.80 +/- 0.22 ms/cm) averaged more than four times that of the adjoining distal (0.19 +/- 0.09 ms/cm) or proximal 1 cm segments (0.19 +/- 0.08 ms/cm). In the remaining 44 (48 per cent) hands, the latency increase was distributed more evenly across the carpal tunnel. Unlike the sensory axons the motor axons were difficult to test serially because of the recurrent course of the thenar nerve, which may be contained in a separate tunnel. The wrist-to-palm latency was significantly greater in the patients with carpal tunnel syndromes than in the controls for sensory (2.18 +/- 0.48 ms v 1.41 +/- 0.18 ms) and motor axons (2.79 +/- 0.93 ms v 1.50 +/- 0.21 ms). Consequently, there was considerable difference between the carpal tunnel syndromes and controls in SNCV (38.5 +/- 7.5 m/s v 57.3 +/- 6.9 m/s), and MNCV (28.2 +/- 4.5 m/s v 49.0 +/- 5.7 m/s). In the remaining distal segment, however, there was only a small difference between the two groups in sensory (1.48 +/- 0.28 ms v 1.41 +/- 0.22 ms) and motor latency (2.15 +/- 0.34 ms v 2.10 +/- 0.31 ms). The exclusion of the relatively normal distal latency made it possible to demonstrate mild slowing across the carpal tunnel in 36 (21 per cent) sensory and 40 (23 per cent) motor axons of 172 affected nerves when the conventional terminal latencies were normal. Sensory or motor conduction abnormalities were found in all but 13 (8 per cent) hands. Without palmar stimulation, however, an additional 32 (19 per cent) hands would have been regarded as normal.

AAEE minimonograph #26: The electrodiagnosis of carpal tunnel syndrome

Abstract: The electrodiagnosis of carpal tunnel syndrome is reviewed, including discussions of old and new techniques of motor and sensory nerve conduction, anomalous innervation, needle electrode examination, and one method of examining a patient with suspected carpal tunnel syndrome. The results of electromyographic testing of 505 patients with carpal tunnel syndrome in Rochester, Minnesota, from 1961 to 1980 are compared with results from previous studies. In the appendixes, a method of performing median motor and sensory nerve conduction studies and Mayo Clinic normal values are provided.