18: NM US of Mononeuropathies

Question 1

Some key examples of measurements for peripheral nerves on U/S, in addition to vascularity and mobility

Answer 1

CSA and AP diameter;
Flattening ratio (nerve width/height when visualized on short axis; normal for median nerve < 3:1);
wrist-to-forearm ratio (ratio greater than 1.4 for median nerve abnormal;
elbow to mid-arm and forearm ratio for ulnar nerve, with greater than 1.5 abnormal

Question 2

When can intraneural ganglia most frequently manifest?

Answer 2

Tear at articular branch of the common fibular nerve

Question 3

Most common benign tumor?

Answer 3

Lipoma

Question 4

What is a neurofibroma? What is a schwannoma?

Answer 4

Tumor of the actual nerve, and spindle-shaped;
Derived from Schwann cells, and slightly eccentric to long axis of the nerve

Question 5

What malignant neoplasm can invade nerves? Which nerve specifically?

Answer 5

Lymphoma (neurolymphomatosis); upper thigh sciatic nerve

Question 6

What is a varix and what can it possibly affect?

Answer 6

Engorged veins or a single large vein;
the distal tibial nerve in the tarsal tunnel