Anomalous Innervation

Question 1

What are the combination patterns that can be seen in anomalous innervation

Answer 1

• CTS and GBA.
• UNE and GBA.
• Peroneal neuropathy at the fibular head and accessory peroneal (small, large, small)

Question 2

CTS and MGA pattern

Answer 2

• Prolonged DL of median at wrist.
• Proximal stimulation with positive dip.
• Factisiously fast CV across the forearm.
• If CTS is severe, DL might be shorter at the proximal stim site compared to the wrist.

Question 3

UNE and MGA pattern

Answer 3

• Slow CV of CB at the elbow ( bet BE and AE)
• Drop in amplitude across the forearm (between wrist and AF_
• Sensory ulnar involvement can occur.
• small CMAP when stimulating median at AF.

Question 4

Peroneal neuropathy at the fibular head and accessory peroneal nerve

Answer 4

Can have small, large, small from distal to proximal.
- CV slowing or CB between below and above fibular sites. (CMAP drop at above fib stim)
- Small CMAP at ankle stim.
- Higher amplitude at below fib compared to ankle and above elbow.
- Stim posterior lateral mal –> small CMAP

Question 5

Riche-Cannieu anastomosis.What is it and EDX findings

Answer 5

Communication between deep palmar bracnh of ulnar and either main motor or recurrent thenar branch in the palm.
- no response median thenar stimulation.
- Normal CMAP with ulnar stimulation recording at the thenar muscle.
-EMG of APB normal.

Question 6

When to suspect Riche-Cannieu anastamosis in a patient with CTS. Other DDx

Answer 6

• Present abnormal sensory median.
• Absent median motor repsonse.
• stim at ulnar recording over thenar: normall CMAP
• Needle EMG normal or mildly abnrmal./
  Other DDX: C8-T1 radiculopathy & lower trunk plexopathy.

Question 7

normal sensory/ or abnormal snesory median (small amplitudes, slow CV.
Absent median motor APB
DDX

Answer 7

• CTS and Riche-Cannieu.
• C8-T1 radiculopathy ( normal SNAPs) & abnormal EMG.
• Lower trunk plexopathy.

Question 8

Severe hand intrinsics weakness DDX

Answer 8

• Median and ulnar neuropathies.
• Lower trunk plexopathy.
• C8-T1 radiculopathy.
• Severe ulnar neuropathy at the elbow with Riche-Cannieu

Question 9

How to test for superficial radial and DUC anomalous anastamosis

Answer 9

Stimulate superfical radial over the radius in the llateral forearm and record over the DUC distribution.

Question 10

What is the LAC anomalous innervation.

Answer 10

• supply motor: median innervated forearm muscles.
  In some cases: thenar muscesl and base of the thumb sensation (palmar cutaneous branch of median)