Procedure 12 Open Carpal Tunnel Release
See Video 10: Open Carpal Tunnel Release
Indications
Diagnosis of carpal tunnel syndrome with one of the following:
Examination/Imaging
Clinical Examination
Phalen test (Fig. 12-1): The patient’s wrist is held in a flexed position for up to 1 minute or until onset of symptoms. A positive test consists of the onset of numbness or paraesthesia in the median nerve distribution. Care must be taken to avoid direct pressure or flexion at the elbow when performing this examination, in order to avoid inducing ulnar nerve symptoms.
Carpal tunnel compression test (Fig. 12-2): The examiner applies direct pressure to the carpal tunnel with his or her thumb for up to 1 minute or until onset of symptoms. A positive test consists of the onset of numbness or paresthesia in the median nerve distribution. As with Phalen test, care is taken to avoid direct pressure or flexion at the elbow when performing this examination.
Tinel sign (Fig. 12-3): The examiner taps directly over the carpal tunnel with his or her long and index fingers. A positive test consists of paresthesia or pain in a median nerve distribution.
Two-point discrimination (tests innervation density; abnormal test is a late finding)
Semmes-Weinstein monofilament test (tests pressure threshold; more sensitive)
Surgical Anatomy
The superficial palmar fascia is a fanlike palmar fascial extension into which the palmaris longus inserts.
The palmar cutaneous branch of the median nerve (PCN) lies between the flexor carpi radialis and palmaris longus tendons in the distal forearm, but its branches may be found up to 6 mm ulnar to the thenar crease in the palm (Fig. 12-4).
The transverse carpal ligament (flexor retinaculum) forms the roof of the carpal tunnel.
The median nerve lies in the volar and radial quadrant of the carpal tunnel.
