HSS Ultrasound of the Month Case 136

Clinical History 55 year old female with numbness of the thumb, index, and middle fingers

Ultrasound of the Month – Case 136

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Ultrasound of the Month – Case 136

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Ultrasound of the Month – Case 136

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Diagnosis: Carpal Tunnel Syndrome The carpal tunnel is a fibro-osseous tunnel in the wrist, partly defined by the transverse carpal ligament (flexor retinaculum), through which runs the median nerve as well as the flexor pollicis longus and flexor digitorum superficialis and profundus tendons.

Carpal tunnel syndrome is median nerve neuritis due to compression and irritation of the nerve within the carpal tunnel.

The cause of carpal tunnel syndrome is usually idiopathic, but anything that decreases the area of the carpal tunnel can potentially contribute to carpal tunnel syndrome.

Carpal tunnel syndrome is usually diagnosed by a combination of physical exam and electrodiagnostic tests.

Ultrasound can easily identify the median nerve and other structures within the carpal tunnel and thus has a role in assessing patients with suspected carpal tunnel syndrome.

Ultrasound of the Month – Case 136

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Diagnosis: Carpal Tunnel Syndrome Much has been published regarding the ultrasound findings that suggest carpal tunnel syndrome.

The most extensively studied is the size of the median nerve, expressed as the cross-sectional area.

Compression of the median nerve within the distal segment of the carpal tunnel results in enlargement of the nerve immediately proximal to the site of compression, and >12 mm2 is often quoted as being suggestive of carpal tunnel syndrome.

Thickening and palmar bowing of the transverse carpal ligament, abrupt caliber change to the nerve at the site of compression (“notch sign”), and flattening of the median nerve have also been described as being suggestive of carpal tunnel syndrome.

Ultrasound of the Month – Case 136

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