Median Nerve Palsy Test

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 Median Nerve Palsy Test


What are the Median Nerve Palsy Tests?

Median Nerve Palsy Tests include the following:

  1. Benediction Hand Sign
  2. Ochsner Test
  3. Carpal Tunnel Sign
  4. Phalen Test
  5. Reverse Phalen Test
  6. Nail Sign
  7. Bottle Test
  8. Pronation Test
See Also: Carpal Tunnel Syndrome

Benediction Hand Sign

The patient is asked to oppose the tip of the thum b and the tip of the little finger. In the next step, the patient is asked to make a fist. Finally, the patient palmar flexes the hand slightly with the fingers extended.

Paralysis of the opponens pollicis makes it impossible to bring the tips of the thumb and little finger into opposition.

Because of weakness of thumb opposition and flexion in the first three digits, the patient cannot make a fist. This produces a typical deformity (Benediction Hand) in which only the ring and little fingers are flexed while the other digits remain extended.

Paralysis of the opponens, abductor pollicis brevis, and flexor pollicis brevis muscles coupled with the antagonistic pull of the adductor pollicis causes the thumb to lie in the plane of the fingers. The thumbnail lies in the same plane as the fingernails, creating a deformity resembling an apes hand, and the patient is unable to oppose the thumb.

Ochsner Test

The patient is asked to join his or her hands with the fingers interlocked.

If median nerve palsy is present, the patient will be unable to flex the index and middle fingers due to partial paralysis of the flexor digitorum profundus.

Ochsner Test
Ochsner test. (a) Normal position. (b) The index and middle fingers extended due to weakness in the flexors

Carpal Tunnel Sign

The patient is asked to keep his or her wrists completely flexed for 1 to 2 minutes.

Paresthesia that occurs or worsens in the region supplied by the median nerve is a sign of carpal tunnel syndrome.

Carpal Tunnel Sign
Carpal Tunnel Sign

Nail Sign

The patient is asked to touch his or her thumb to the tip of the little finger.

Median nerve palsy will produce paralysis of the opponens pollicis. The thumb cannot be opposed but will only move along an arc in adduction toward the palm .

Nail Sign - Median Nerve palsy
Nail sign. (a) Normal. (b) Abnormal position due to weakened opposition of the thumb.

Bottle Test

The patient is asked to grasp a bottle in each hand between the thumb and index finger.

In paralysis of the abductor pollicis brevis, the web between the thumb and index finger will not be in contact with the surface of the bottle.

The patient will be unable to hold the bottle between the thumb and index finger in such a way that the hand is in continuous contact with the circumference of the bottle.

Bottle Test - Median nerve palsy
Bottle test. (a) Normal. (b) Abnormal

Pronation Test

Pronation Test is used in assessment of pronator teres and pronator quadratus pathology.

The patient is seated with both hands and forearms in supination on the examining table. The examiner asks the patient to pronate his or her forearms, initially normally and then against the resistance of the examiner’s hand.

Weakness in active pronation against resistance in one arm as compared with the contralateral side indicates a median nerve lesion. The lesion normally lies at the level of the elbow. In the presence of a median nerve lesion distal to the elbow, the patient may be able to actively pronate the forearm against resistance because the pronator teres is still largely functional.

Pronation Test
Pronation test. (a) Starting position. (b) Weakness in pronation of the right arm.

OK Sign (Pinch Sign)

The pinch mechanism is a combined motion involving several muscles. Normally the thumb and index finger form the shape of an “O.”

With normal function in the muscles involved, the examiner will be unable to change the shape of the “OK sign” by pulling with his or her own index finger inserted between the patient’s thumb and index finger.

In an anterior interosseous nerve syndrome with paralysis of the flexor digitorum profundus of the index finger and flexor pollicis longus, the thumb and index finger remain extended in the distal interphalangeal joints. The patient is then unable to form a proper “OK sign” with the thumb and index finger.

OK sign
(a) Normal. (b) Abnormal result with paralysis of the flexor digitorum profundus of the index finger and flexor pollicis longus.

Wrist Flexion Test

Wrist Flexion Test is used to assess the distal nerve lesion in the forearm.

The patient is seated with both forearm s supinated. The examiner asks the patient to ex his or her wrists, first normally and then against the resistance of the examiner’s hands.

Weakness in active flexion against resistance indicates paresis or paralysis of the flexors in the forearm , especially the flexor carpi radialis.

Weakness in this motion without resistance is a sign of complete paralysis.

Weakness in active flexion against resistance indicates a problem with the median nerve at the level of the elbow or further proximally.

Complete inability to flex the wrist against resistance could indicate a lesion involving both the median and ulnar nerves.

Wrist Flexion Test
Wrist Flexion Test

Phalen Test & Reverse Phalen Test

See also: Phalen Test & Reverse Phalen Test.

References

  1. Alsaffar RM, Hameed S. Benediction Sign. [Updated 2021 Apr 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554458/
  2. Dididze M, Tafti D, Sherman Al. Pronator Teres Syndrome. [Updated 2021 Aug 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526090/
  3. Clinical Tests for the Musculoskeletal System 3rd Edition.



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