Keywords:
Neuroradiology peripheral nerve, Extremities, Trauma, Ultrasound, Diagnostic procedure
Authors:
O. K. Nwawka, Y. Endo, T. Miller; New York City, NY/US
DOI:
10.1594/essr2017/P-0280
Imaging findings OR Procedure Details
ULTRASOUND IMAGING TECHNIQUE
For successful upper extremity peripheral nerve imaging,
high-resolution transducers are recommended.
At our institution,
12-18 MHz transducers are routinely employed.
NORMAL SONOGRAPHIC APPEARANCE OF THE RADIAL NERVE
The easiest way to identify the radial nerve is at the level of the distal humerus.
With the arm supinated,
the transducer is placed at the radial aspect of the distal upper arm,
just above the antecubital fossa (Figure 1).
The resultant image will be one of the brachioradialis at the level of the capitellum.
The radial nerve is seen as an echogenic bundle of fascicles (Figures 2,
3) deep to the brachioradialis and above the brachialis muscle.
The radial nerve can be tracked proximally from the level of the brachioradialis to the spiral groove (Figure 3),
along the posterior aspect of the arm,
and then towards the axilla.
When tracked distally from the capitellum,
the radial nerve will bifurcate into the deep and superficial branches,
just distal to the antecubital fossa.
The superficial radial nerve is easily tracked distally down the forearm,
visualized deep to the brachioradialis muscle (Figure 4),
through the radial wrist.
The deep branch of the radial nerve is traced distally around the radial aspect of the proximal forearm towards the posterior elbow (Figure 5).
Under sonography,
the DBRN is visualized entering into the supinator tunnel and then in fascia between the two supinator heads (Figure 5).
The DBRN can then be followed as it exits the supinator fascia into the extensor compartment at the proximal posterior forearm where it becomes the posterior interosseous nerve (Figure 6).
CASE ONE (Figure 7):
62 y/o man with right triceps and wrist extensor weakness following ORIF of mid-humerus fracture performed at an outside hospital 1 month prior.
CASE TWO (Figure 8):
56 y/o man with left triceps and wrist extensor weakness following a mid-humerus fracture 2 months prior.
CASE THREE (Figure 9):
35 y/o woman with right triceps,
wrist and hand extensor weakness following ORIF for mid-humerus fracture 5 months prior.
CASE FOUR (Figure 10):
36 y/o man with dorsal right hand and forearm sensory loss following repair of distal biceps tear at an outside hospital.
CASE FIVE (Figure 11):
45 y/o woman with right wrist extension weakness following a deep branch radial nerve schwannoma resection performed at an outside institution.
CASE SIX (Figure 12):
51 y/o man with right wrist extensor weakness following a distal bicep repair performed at an outside institution.