Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper extremities. CTS is caused by chronic and focal compression of the median nerve trunk through the carpal tunnel, causing demyelization. Patients typically present with paresthesias in the wrist and sometimes in the distribution of the median nerve (palmar aspect of the first, second, and third fingers; radial half of the fourth finger). Symptoms are typically worst upon arising in the morning or after repetitive use.
CTS is more common in women than in men and has a peak of prevalence after age 55 years. CTS has multiple etiologies and is related to any condition that acts as an "occupation space" in this limited anatomical area.
CTS may occur with the following:
Congenital disorders: anatomical anomalies, skeletal dysplasia
CTS may also be posttraumatic (eg, job or sports-related injuries) or occur concurrent with other nerve compression syndromes (especially ulnar tunnel syndrome).
The patient in this case has CTS due to a volar ganglion cyst that acted as an "occupation space" lesion from the distal aspect of the radius to the tubercle of scaphoid bone. Another volar ganglion originates from the scaphotrapezium capsule.
Diagnosis of CTS is clinical and should include the following:
Tinel test: A positive Tinel sign consists of triggering the symptoms (pain or paresthesias in the fingers innervated by the median nerve) after repeatedly tapping the volar surface of the patient's transverse carpal ligament. It has a sensitivity of 36%-50% and a specificity of 77% for CTS.
Phalen maneuver: With a positive Phalen maneuver, symptoms are triggered after flexing the patient's wrist 90°, with the elbow in full extension and maintaining this position for 60 seconds. The Phalen maneuver has a sensitivity of 57%-68% and a specificity of 58%-73% for CTS. When performed in combination with the median nerve compression test, the sensitivity increases to 80% and the specificity increases to 92%.
Median nerve compression test: The symptoms appear within 30 seconds of applying direct pressure over the transverse carpal ligament. A positive finding has a sensitivity of 64% and a specificity of 83% for CTS.
Hand elevation test: A positive test result consists of the appearance of symptoms after the patient raises his or her hands above the head for 1 minute. It has similar sensitivity and specificity to that of the Phalen maneuver and the Tinel test.
Flick sign: This sign is positive when the patient wakes with symptoms that are alleviated by shaking the hand. It has 93% sensitivity and 96% specificity for CTS.
Thumb abduction weakness test: If positive, the symptoms appear after raising the patient's thumb perpendicular to the palm, followed by downward pressure on the distal phalange while the patient resists. It has a sensitivity of 29%-65% and a specificity of 65%-80% for CTS.
Thenar atrophy assessment: The presence of thenar atrophy has a sensitivity of 12%-16% and a specificity of 90%-94% for CTS.
Hypoalgesia test: A positive result occurs with decreased sensation to pain on the palmar aspect of the second finger (compared with the fifth finger on the same hand). It has a sensitivity of 39% and a specificity of 88% for CTS.
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