Ulnar Nerve Palsy (OSCE Guide)

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1/03/2020

Ulnar Nerve Palsy (OSCE Guide)

The examination of hand for neuropathies is commonly encountered at OSCE stations. Ulnar Claw-hand is a very characteristic finding in Ulnar nerve palsy.

Firstly, introduce yourself and get consent before you proceed to examine the patient.


ULNAR NERVE PALSY – EXAMINATION

Given below is a targeted examination for Ulnar nerve palsy. But remember to examine other nerves (Median & Radial) to exclude multiple nerve involvement.

  1. Ask the patient to spread out the hands for you and try to spot diagnose the “Ulnar claw hand” (Clawing of the medial two fingers of the hand).
  2. Inspect carefully both the palmar and dorsal aspect of the hands and look for,
    • Wasting of hypothenar eminence (compare with the other side).
    • Dorsal guttering (due to wasted Interossei muscles) – Palpate the 1st finger web where the wasting is often obvious.
  3. Examine the functions of the muscles supplied by the Ulnar nerve.
    • Palmar Interossei – Ask the patient hold a card between two fingers while you attempt to pull it away using the same two fingers.
    • Dorsal Interossei – Ask the patient to keep the hand on a flat surface and spread out the fingers against resistance.
    • Adductor Pollicis – Ask the patient hold a paper between the thumb and the radial aspect of the index fingers while you attempting to pull it away. Flexion of the terminal phalanx of the thumb to hold the paper indicates a positive Froment’s sign.
  4. Examine the sensory distribution.
    • High lesions – There is an area of sensory loss over both palmar & dorsal aspects of the medial side of the hand and medial one and half fingers.
    • Low lesions – There is an area of sensory loss only over the palmar aspect of the medial side of the hand and medial one and half fingers.
  5. Try to identify a probable aetiology.
    • Look for depigmented anaesthetic patches and Ulnar nerve thickening at the elbow (Leprosy).
    • Look for scars on the forearm (trauma).
  6. Offer to assess the patient’s quality of life.

PRESENTATION

There is marked clawing of the ring and little fingers of the right hand and there is wasting of hypothenar eminence with dorsal guttering, but the thenar eminence is not affected. The actions of palmar and dorsal interossei are impaired and Froment’s sign is positive.

The opposition of the thumb and finger extension is intact. There is an area of sensory loss over the palmar aspect of the medial side of the hand and medial one and half fingers. There is no hypopigmented patches or ulnar nerve thickening and there are no visible scars on the forearm.

So my tentative diagnosis is right-sided Ulnar nerve palsy, probably a lower lesion.



FREQUENTLY ASKED QUESTIONS

1. What is “Clawing”?

It is the hyperextension of the metacarpophalangeal joints and flexion of proximal and distal interphalangeal joints.

2. Why does it occur?

It is due to paralyzed Interossei and Lumbricals with unopposed action of long flexors and extensors.

3. What is “Ulnar claw hand”?

The clawing is only obvious in medial two fingers (Because lateral two Lumbricals which are supplied by the median nerve are spared).

4. What is the “Ulnar paradox”?

Surprisingly, high division of the ulnar nerve (anywhere hand’s breadth above the wrist) causes less clawing than the lower lesions.

5. What is the anatomical basis of the Ulnar paradox?

In higher lesions the innervation to the medial half of Flexor Digitorum Profundus is also lost, causing less intense flexion of the fingers.

6. How do you differentiate?

From the degree of clawing and the area of sensory involvement (see examination).

7. What are the muscles that are innervated by the Ulnar nerve?

1. Flexor Carpi Ulnaris.
2. Medial half of Flexor Digitorum Profundus.
3. All Palmar Interossei.
4. All dorsal Interossei.
5. 3rd & 4th Lumbricals.
6. Adductor Pollicis

8. What is the basis of Forment’s sign?

The patient tries to compensate for the ‘lost’ adduction of the thumb by flexion of it (with Flexor Pollicis Longus which is supplied by the Median nerve).

9. What are the causes of Ulnar nerve palsy?

1. Leprosy (often bilateral).
2. Laceration over the wrist or anywhere along its course.
3. Fracture medial epicondyle.
4. Dislocation of elbow.
5. Cubital tunnel syndrome.
6. Degenerative arthritis.
7. Malunion of fractures of the lower end of the humerus (Tardae Ulna nerve palsy).

10. What are the surgical options for Ulnar nerve palsy you know of?

1. Ulnar nerve decompression.
2. Ulnar nerve anterior transposition.
3. Medial epicondylectomy.

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