22: UNE

Question 1

At what level does the palmar cutaneous sensory branch come off? What does it supply?

Answer 1

Ulnar styloid;

proximal medial palm

Question 2

Most likely cause of UNE? Other causes?

Answer 2

External compression and repeated trauma;

tumor, ganglia, accessory muscles, fibrous bands

Question 3

What is the cubital tunnel known as?

Answer 3

Humero-ulnar aponeurosis (HUA)

Question 4

How does Benediction posture and Wartenberg’s sign come about?

Answer 4

Hyperextended MCP joints, proximal and distal IP joints flexed (3rd and 4th lumbrical weakness); with fingers and thumb abducted (weak adductor pollicis and interossei weakness);
Weakness of third palmar interosseous

Question 5

When performing ulnar conduction studies, what is a major concern?

Answer 5

Artifactual slowing of conduction velocity across the elbow due to underestimation of true nerve length

Question 6

With inching study, what increase in latency suggests demyelination?

Answer 6

.5 msec

Question 7

Theories as to why FCU can be spared in UNE?

Answer 7

Differential fascicular susceptibility or “dying back” concept of nerve lesions with most distal muscles affected

Question 8

Important ratio for ulnar nerve U/S? Above what CSA is typically considered abnormal?

Answer 8

Largest CSA at the elbow (cubital tunnel or retrocondylar groove) compared to CSA at mid-forearm or mid-arm, with above 1.5 abnormal;
10 mm2