Phalen sign

Phalen's maneuver is a diagnostic test for carpal tunnel syndrome discovered by an American orthopedist named George S. Phalen. Phalen's maneuver is a diagnostic test for carpal tunnel syndrome discovered by an American orthopedist named George S. Phalen. The patient is asked to hold their wrists in complete and forced flexion (pushing the dorsal surfaces of both hands together) for 30–60 seconds. The lumbricals attach in part to the flexor digitorum profundus tendons. As the wrists flex, the flexor digitorum profundus contracts in a proximal direction, drawing the lumbricals along with it. In some individuals, the lumbricals can be 'dragged' into the carpal tunnel with flexor digitorum profundus contraction. As such, Phalen's maneuver can moderately increase the pressure in the carpal tunnel via this mass effect, pinching the median nerve between the proximal edge of the transverse carpal ligament and the anterior border of the distal end of the radius. By compressing the median nerve within the carpal tunnel, characteristic symptoms (such as burning, tingling or numb sensation over the thumb, index, middle and ring fingers) conveys a positive test result and suggests carpal tunnel syndrome. Because not all individuals will draw the lumbricals into the carpal tunnel with this maneuver, this test cannot be perfectly sensitive or specific for carpal tunnel syndrome. In studies of diagnostic accuracy, the sensitivity of the Phalen's maneuver ranged from 51% to 91% and its specificity from 33% to 88%.