Case 5

30 y/o male came to the ED s/p sustaining a laceration across the palmar aspect of his non-dominant left hand. The posture in the picture below was elicited during the full neurovascular exam of his hand. What is the name of the sign & what is its significance?

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Answer: Claw hand from ulnar nerve injury.

Discussion: OK. This was a little unfair since I did not tell you what the patient was attempting to do when this sign was elicited. However, you have a whopping clue from the blood stain on the ulnar aspect of the hand. The emergency physician should know the full neurovascular exam of the hand. Not only is it useful in caring for patients, it also come in handy on the boards (no pun intended).

	Radial	Ulnar	Median
motor	wrist extension	spread fingers	thumb opposition
sensory	dorsum 1^st web space	ring & little fingers	tip of index finger
deficit	wrist drop	claw hand	ape hand

Ulnar neuropathy is of particular interest and requires urgent follow-up to an orthopedic hand specialist. The sensation of the ulnar aspect gives a warning whenever we foolishly lay our hand on something hot or cold.

Pearl: Motor functions can be tested by the thumb alone. If the thumb can go through a full ROM from full extension (extensor pollicis), to thumb parallel against the hand (interossei), to opposition against the palm (oppenens pollicis). The mnemonic RUM demonstrates the nerve tested – Radial, Ulnar, Median.

Other nerve injuries from orthopedic problems of interests on the boards include:

shoulder dislocation - axillary (shoulder abduction)

humeral shaft - radial (wrist extension)

elbow, supracondylar - median (thumb opposition)

elbow, lateral epicondyle - ulnar (finger abduction)

hip dislocation - sciatic (knee flexion, foot & toe flexion)

knee dislocation - tibial (foot flexion)

fibular neck - peroneal (foot extension)