Peripheral Nerve:
Trauma and Surgery for Peripheral Nerves
Transcript:
Guest: Dr.
Abhay Varma – Neurosurgery
Host: Dr.
Linda Austin – Psychiatry
Dr. Linda Austin:
I’m Dr. Linda Austin, talking, today, with Dr. Varma, who is Assistant
Professor of Neurosurgery here, at MUSC.
Dr. Varma, let’s talk about surgery of the peripheral nerves. Now, the peripheral nerves are those that go
from the spinal cord out to the arms and legs.
So, what are some examples, then, of some of the conditions of trauma
that you need to repair in a surgical practice?
Dr. Abhay Varma:
We see trauma of peripheral nerves in all age groups, starting from even
newborns. We sometimes see what is
called brachial plexus injury, or obstetrical brachial plexus injury that results
from pulling of the arm during delivery.
It can lead to injury to the nerves that run from the neck down into the
arm.
Dr. Linda Austin:
Where is the brachial plexus?
Dr. Abhay Varma:
The brachial plexus is located above the collar bone. I’m sure most people understand what the
collar bone is. In that small area just
above the collar bone, it runs from the neck down into the arm. During birth, if the arm is stretched excessively
for whatever reason, it can lead to pulling or tearing of the nerves running
from the neck to the arm, causing weakness in the baby’s arm.
Dr. Linda Austin:
How do you repair that in a baby?
Dr. Abhay Varma:
Initially, we like to wait and see if it improves on its own; in many
cases, it improves on its own. But, if by
three or five months we see that there is a persistent weakness, we recommend
exploration to see what’s going on.
Before that, we like to get nerve conduction studies done to see what
nerves are intact. But, ultimately, the
best is to explore if the baby is not showing signs of full and spontaneous
improvement. We can repair it by using
the baby’s own nerves from the legs, where small pieces of nerves are taken
from sensory nerves in the legs and they’re used to repair the injured nerves
in the brachial plexus.
Dr. Linda Austin:
Can there be brachial plexus injuries in adults as well?
Dr. Abhay Varma:
It can happen, definitely. It can
follow auto accidents or any kind of accident where there was stretching or
pulling of the arm. It can also follow
gunshot injuries, or stab injuries to that area on the body.
Dr. Linda Austin:
So then, basically, is the technique the same? You harvest a nerve from the leg and actually
move it up to where you have a problem and stitch it back into place?
Dr. Abhay Varma:
Yes. We would need to harvest a
nerve if the gap between the two ends of the injured nerve is so big that we
cannot bring the two ends together without any tension. So, if the gap is big, we would need to
harvest a nerve. But if, sometimes, like,
following a stab injury where there’s a sharp weapon used to produce a clean
cut in the nerve, the two ends can be brought together and we can repair the
nerve without having to harvest another nerve from the body.
Dr. Linda Austin:
That sounds like very delicate surgery.
Dr. Abhay Varma:
It’s done under microscope and good training.
Dr. Linda Austin:
What’s the longest that those procedures can take, let’s say, in a baby
with a brachial plexus injury?
Dr. Abhay Varma:
In some of the centers which are doing these surgeries on a regular
basis, they have reported their operative time as close to two hours. Otherwise, it can take anywhere from four to
six hours, depending on the severity of injury and the complexity of repair.
Dr. Linda Austin:
And I would guess that’s likewise in an adult, after a motor vehicle
injury or something like that.
Dr. Abhay Varma:
Yes. It also depends on how badly
scarred that area is. If there’s
extensive scarring in that area, one has to very meticulously and carefully cut
through the scar to identify the nerves and identify the cut ends of the nerves
before you can do any kind of repair.
Dr. Linda Austin:
Now, you mentioned that, in trauma, like an accident, sometimes there’s
stretching of the nerve while other times, actually, the nerve can be
torn. If there is just stretching, what
do you do? How do you repair that?
Dr. Abhay Varma:
It depends on what parts of the nerves are stretched and torn during the
accident. If there is stretching of just
axons and the outer layers are intact, it may be possible for the axon to grow
spontaneously. By axon, I mean, the
conducting part of the nerve through which the impulses are conducted. It may be possible for it to grow back on its
own without requiring any surgical intervention. However, if there’s severe stretching which
leads to not only disruption of the axon, or the conducting part of the nerve,
but also the outer layers, which kind of provide a sheath around the axons,
then the axons may not be able to repair or grow on their own. This may need surgical intervention with some
kind of repair, a primary repair, where you don’t need a graft, or a repair
using a graft.
Dr. Linda Austin:
How do you evaluate this before you take the patient to surgery?
Dr. Abhay Varma:
There are different ways of evaluating it. The most important is the clinical
evaluation. There’s no substitute for a
good clinical exam, where you carefully examine the patient. A careful clinical examination can tell you
the level of the injury and its severity.
We also have newer techniques, MRI imaging, for example, which can help
us diagnose a nerve injury and see if there’s any evulsion of the nerve from
this point where it’s coming off the spinal cord.
Dr. Linda Austin:
Evulsion, meaning?
Dr. Abhay Varma:
Tearing of the nerve as it comes off the spinal cord. We also have electrophysiological studies
where we study the conduction through the nerves and the condition of the
muscles that these nerves supply. That
helps us know the severity of the injury and what the prognosis is. If the muscle is completely destroyed because
it’s been a long standing injury, and even if you repair the nerve, it’s
unlikely that the muscle would recover, we can tell the patient beforehand.
Dr. Linda Austin:
Dr. Varma, thank you very much.
Dr. Abhay Varma:
You’re welcome.
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