Chapter 56 D. Peripheral Nerve Trauma

Question 1

Question 56D-1: 
Which of the following types of peripheral nerves are most sensitive to traumatic injury? 
A.  Large-diameter myelinated axons 
B.  Small-diameter myelinated axons 
C.  Unmyelinated axons 
D.  There is no substantial difference

Answer 1

Answer 56D-1: A ..
Large-diameter mvelinated a’wos are the most
sensitive to trauma, although penetrating
injuries will damage all. These are motor and
sensory nerves, although clinical fwdings
show more prominent motor involvement.
(p1182)

Question 2

Question 56D-2: 
Segmental demyelination of a peripheral nerve suggests which type of injury? 
A.  Compression 
B.  Penetrating injury 
C.  Ischemic damage
D.  Toxic damage

Answer 2

Answer 56D-2: A.
Compression of peripheral nerves can damage
the myelin sheath with the axons being
relatively tntact. This results in segmental
demyelination. Mild damage can result in
slowing of conduction, whereas more severe
lesion results in blockade of conduction.
(p1182)

Question 3

Question 56D-3:
An infant presents to you with Erb’s palsy with damage to the upper brachial plexus. How would you advise the parents of the injury and prognosis?
A. The damage is from stretch and damage to the myelin sheath, and prognosis is excellent
B. The damage is mainly to the axons from stretch, and prognosis is variable and too soon to predict
C. The damage is to both the axons and myelin sheath, and prognosis for recovery is poor

Answer 3

Answer 56D-3: B,
Stretch of the brachial plexus results in
damage mainly to the axons, although the
myelin sheath can be affected, depending on
the severity of the injury. Prognosis is
variable, and depends on the rate of recovery
- some improvement within the first two
weeks indicates a good prognosis, whereas
lack of substantial improvement within 4
months suggests a poor prognosis. (p1187,
2527)

Question 4

Question 56D-4:
A heroin addict presents with left median neuropathy secondary to repeated injection into the fore&rm. He never bad an injection directly into the nerve that he remembers, but has had gradual progressive loss of left median nerve function. Examination shows the proximal forearm near the antecubital fossa to be fibrotic. Which is appropriate treatment?
A. Analgesics
B. Corticosteroids
C. Surgical intervention in the foreann
D. Surgery at the carpal tunnel

Answer 4

Answer 56D-4: C.
Fibrotic changes in the nerve can develop due
to repeated injections, even if there was no
direct injection into the nerve. Surgery can be
helpful, providing there is no further injection
into the area. (p 1188)