Nerve: Tumors of the Peripheral Nerve
Guest: Dr. Abhay Varma - Neurosurgery
Host: Dr. Linda Austin – Psychiatry
Linda Austin: I’m Dr. Linda Austin. I’m talking, today, with Dr. Varma who is
Assistant Professor of Neurosurgery here at Medical University of South
Carolina. Dr. Varma, let’s turn our
attention now to tumors of the peripheral nerves. Now, these are the nerves that are extending
out from the spinal cord. What are the
most common nerve tumors that you see?
Abhay Varma: The two most common nerve
tumors that we see are what are call neurofibromas and trinomas. Neurofibromas are tumors that tend to engulf
the entire nerve and trinomas are tumors which are more discreet and easier to
dissect from the nerves. The less common
ones are the malignant tumors coming from the peripheral nerves.
Linda Austin: So, first, to talk about
the neurofibromas, these can be multiple tumors, correct?
Abhay Varma: These can be multiple
tumors in certain conditions, yes.
Linda Austin: And, are they usually
multiple, are there usually lots and lots of them?
Abhay Varma: Yes. In certain genetic conditions, like
neurofibromatosis, they can be multiple and they can afflict the entire
body. They can be in the arms and the
legs or the abdomen and even the face and the scalp.
Linda Austin: And these can be visible,
so they can be unsightly.
Abhay Varma: They can definitely be visible
and they can be unsightly as well as uncomfortable for the patient.
Linda Austin: What is the discomfort and
what is the loss of function for people with neurofibromatosis?
Abhay Varma: The discomfort is, if it is
on a pressure point, it can be painful, and, again, if the tumor is involving a
motor nerve or a major sensory nerve, or one the plexus, where multiple nerves
make a network in the body, that can lead to loss of function. Also, if a tumor develops in a small space,
it can lead to pressure on the nerve and, again, loss of function, depending on
what kind of nerve it is.
Linda Austin: Now, you mentioned
earlier, in passing, that these are tumors that affect the entire nerve. It’s not just they wrap around the nerve, but
go through and through. So, what does a
surgery consist of?
Abhay Varma: Well, these tumors and
neurofibromas, like I said, tend to grow and engulf the entire nerve. Surgery in these cases is difficult. It can require excising the whole tumor and
then putting a graft between the two cut ends of the nerve. In some cases we may be able to do what is
called debulk the tumor or partially remove the tumor if complete excision is
not possible. But, between the
neurofibromas and trinomas, neurofibromas offer a bigger challenge.
Linda Austin: You mentioned using a
graft. And I think, in an earlier
podcast, you described how grafts can be taken from certain areas of the body. I would imagine, though, if there are
multiple tumors, you can only do that so many times, is that right?
Abhay Varma: That’s right.
Linda Austin: Don’t you run out of graft
material to use?
Abhay Varma: You will. If there are multiple tumors, you don’t
really go after each tumor. The
indications for tumors are, you know, if it is causing loss of function, for
example, as I mentioned, small spaces in the body where there’s not enough room
for the tumor to grow, so as it grows, it presses on the nerve, leading to loss
of function; or, if it’s in an area where it’s uncomfortable or painful for the
patient; or, as you mentioned earlier, if it is unsightly and, cosmetically,
the patient wants it removed. But, in
patients with neurofibromatosis, there’s really no indication for removing each
and every tumor because new ones can keep appearing.
Linda Austin: Are there any medications
that are useful for this illness?
Abhay Varma: I’m, personally, not aware
of any medication that can control nerve tumors or make one that is already
there go away.
Linda Austin: Anything on the horizon?
Abhay Varma: I’m not aware of anything
right now. But we do have, now,
procedures where we can diagnose it early.
But even if you diagnose, I’m not sure if we have anything available
right now that can make it go away or prevent development of these tumors.
Linda Austin: Is this genetic?
Abhay Varma: It is genetic, yes.
Linda Austin: So, if one parent has this
disorder, what are the odds that a child will have it?
Abhay Varma: It depends on how it is
transmitted. Usually, it’s out of some
dominance. If one parent has it then
there’s a 50 percent chance. But there’s
also something called sporadic cases where the chain in the gene develops
spontaneously in the growing fetus and leads to development of this disease, in
absence of the disease in either of the parents.
Linda Austin: I see. So, it just happens randomly?
Abhay Varma: Yes.
Linda Austin: But, just to reassure
family members, let’s imagine a grandparent has it, their adult child does not
have it, it’s unlikely, then, that it would skip a generation because you would
have expected to have seen it in the parent.
Is that right?
Abhay Varma: Yes. It also depends on the degree of
penetration. If there’s not enough
penetration in one generation but it gets transmitted to the next with some
degree of penetration, it may manifest, yes.
Linda Austin: Now, an easier situation
for you, and, I’m sure, for the patient too, is a schwannoma. What is a schwannoma?
Abhay Varma: A schwannoma is a tumor
arising from the cells of the peripheral nerve, called Schwann cells. This kind of tumor, rather than engulfing the
whole nerve, tends to grow eccentrically from part of the nerve and doesn’t
involve the rest of the nerve. So, under
the microscope, it is possible to dissect it out and remove the tumor without
having to sacrifice or damage the rest of the nerve.
Linda Austin: What do you mean when you
Abhay Varma: It means that it is growing
away from the nerve, rather than wrapping around the nerve.
Linda Austin: How long can those
procedures take, to dissect that?
Abhay Varma: Again, depending on the
complexity of the tumor, how deep it is, what the surrounding critical structures,
many times, you know, you have important blood vessels and other nerves around
it, it can take anywhere from less than an hour to maybe two or three hours.
Linda Austin: Where do these tumors
Abhay Varma: They can arise all over the
body, but most often, I would say, in the upper and lower extremities. That is the most common site where we would
need to operate on them because it can lead to loss of function. Over the torso, we may have to operate if
there’s any doubt about the diagnosis or there’s suspicion of malignancy.
Linda Austin: If a person has one
schwannoma, are they likely to get a second or a third?
Abhay Varma: Yes. One has to be careful. If we do see a patient with a schwannoma, we
first have to make sure that it’s not part of a genetic disorder that the
patient may have. If a person has one
known schwannoma then the odds of him/her developing more schwannomas is higher
than somebody who does not have a schwannoma.
Linda Austin: Dr. Varma, thank you very
Abhay Varma: You’re welcome.
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