The presentation of a patient’s hand may provide insight to whichnerve is damaged and the approximate location of the damage. When presentingwith ulnar n. damage, a patient may show a claw hand, Wartenberg’s sign, orFroment’s sign. Claw hand will present with clawing of the fourth and fifthdigits due to the inability to extend the fingers specifically at theinterphalangeal joints. This presentation is due to the lack of innervation tothe intrinsic muscles of the hands, and the unopposed action of the flexor digitorum profundus m. (Moore et al.,2018).This indicates damage near the distal end of the ulnar n., below the elbow, and potentially near the wrist. Wartenberg’s sign will be seen as the inability to adduct the fifth digit when extended as well as an inability to cross the second and third digit. This is due to ulnar n. injury leading to wasting of the fifth interosseous m. This causes the fifth digit to rest in a more abducted position due to the unbalanced action of the extensor digiti minimi m. (Ebraheim, 2021). There willalso be loss of function of the lumbrical m. in the fourth and fifth digits. A Froment’s test will detect palsy of the ulnar n. resulting from compression in the cubital tunnel. When asking the patient to pinch a piece of paper between their thumb and second digit, a positive Froment’s Sign will show as the patient flexing their thumb’s interphalangeal joint to grip the paper as the paper is pulled away (Attum, 2021). This will result from a weak adductor pollicis m. due to ulnar n. palsy.
Depending on the location of a lesion to the median n., thepatient will present with one of three signs. A positive Benedictine sign willbe caused by proximal median n. damage. It will be seen as paralysis of thefirst and second digit, with weakness to the third digit. A proximal lesionwould lead to paralysis of several muscles (FDS, FPL, FPB, and the radial halfof FDP), leaving the ulnar half of the flexor digitorum profundus m. as theonly remaining flexor (Ebraheim, 2021). When the patient is asked to make a fist, the hand will resemble the similar position taken during a blessing. A positive Benedict sign will also resemble the ulnar claw hand. However, the Benedict sign will present when the patient is flexing, not extending the fingers (Ebraheim, 2021). A mediann. injury affecting the anterior interosseous n. branch will present as an inability to do the OK sign. This occurs due to paralysis of the flexor pollicus longus m. and the lateral part of the flexor digitorum m. (Moore et al., 2018). A positive Ape hand(Simian hand) is caused by paralysis of only the thenar m. from damage tothe recurrent branch of the median n. to the thenar m. The thumb will be seen in the same plane as the other digits due the thumb being pulled more dorsal by the action of the adductor pollicis m., which is innervated by the ulnar n. (Moore et al., 2018).
Finally, proximal radial n. damage will be seen as wrist drop.This is usually caused by fractures of the distal third of the humeral shaft(Holstein-Lewis Fracture) and caused paralysis of the wrist and fingersextensors (Ebraheim, 2010). Lowerradial n. injury will present in the patient as the ability to extend thewrist, but the loss of finger extension. There will be no wrist drop, but thepatient would not be able to make a hitchhiking sign.
Reference List
Attum B. Physical exam of the hand [Internet].Orthobullets. Lineage Medical, Inc.; 2021 [cited 2021Oct21]. Available from:https://www.orthobullets.com/hand/6008/physical-exam-of-the-hand
Ebraheim N. Anterior Interosseous Nerve Injury -Everything You Need To Know - Dr. Nabil Ebraheim [Internet]. YouTube. 2021[cited 2021Oct21]. Available from: https://www.youtube.com/watch?v=M9y-iDKLDPE
Ebraheim N. Claw Hand, Ulnar Claw Hand - Everything YouNeed To Know - Dr. Nabil Ebraheim [Internet]. YouTube. 2017 [cited 2021Oct21].Available from: https://www.youtube.com/watch?v=GyqaKGg3HmM
Ebraheim N. Nerve Injury Position of the Hand &Fingers - Everything You Need To Know - Dr. Nabil Ebraheim [Internet]. YouTube.2021 [cited 2021Oct21]. Available from:https://www.youtube.com/watch?v=nwd1h0Dfo5o
Ebraheim N. Radial Nerve Palsy, injury - WRIST DROP .Everything You Need To Know - Dr. Nabil Ebraheim [Internet]. YouTube. 2010 [cited2021Oct21]. Available from: https://www.youtube.com/watch?v=_Cu6ttAhe8Y
Moore KL, Dalley AF, Agur A. Clinically Oriented Anatomy.8th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2018.
