23: Ulnar Neuropathy at Wrist

Question 1

Which branch of the ulnar nerve gives off the branch to the palmaris brevis?

Answer 1

Superficial

Question 2

What branch of ulnar nerve innervates ADM, FDM, ODM?

Answer 2

Deep branch (deep palmar motor)

Question 3

What does the deep palmar motor branch innervate more distally?

Answer 3

Lumbricals 3 and 4; the dorsal and palmar interossei, adductor pollicis, and deep head of FPB

Question 4

What sign can be seen with severe lesion of the deep palmar motor branch?

Answer 4

Palmaris brevis sign

Question 5

Most common cause of ulnar neuropathy at wrist? Other common causes?

Answer 5

Ganglion cyst within Guyon’s canal;

trauma and wrist fx

Question 6

What would be expected with FDI latency and CMAP amplitude with lesions of distal deep palmar motor branch?

Answer 6

Prolonged; decreased

Question 7

Why could the dorsal ulnar cutaneous sensory potential be spared with UNE?

Answer 7

Again, preferential fascicular sparing of the DUC sensory fibers

Question 8

Supposedly, what are the most sensitive and specific studies for localizing ulnar lesion to the wrist?

Answer 8

Conduction block across the wrist and a slowed wrist-to-palm conduction velocity recording the FDI

Question 9

What muscle can affect the ulnar nerve at the wrist?

Answer 9

Accessory ADM