Peripheral Nerve: Tumors of the Peripheral Nerve

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Peripheral Nerve: Tumors of the Peripheral Nerve




Guest:  Dr. Abhay Varma - Neurosurgery

Host:  Dr. Linda Austin – Psychiatry


Dr. 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?


Dr. 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.


Dr. Linda Austin:  So, first, to talk about the neurofibromas, these can be multiple tumors, correct?


Dr. Abhay Varma:  These can be multiple tumors in certain conditions, yes.


Dr. Linda Austin:  And, are they usually multiple, are there usually lots and lots of them?


Dr. 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.


Dr. Linda Austin:  And these can be visible, so they can be unsightly.


Dr. Abhay Varma:  They can definitely be visible and they can be unsightly as well as uncomfortable for the patient.


Dr. Linda Austin:  What is the discomfort and what is the loss of function for people with neurofibromatosis?


Dr. 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.


Dr. 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?


Dr. 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.


Dr. 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?


Dr. Abhay Varma:  That’s right.


Dr. Linda Austin:  Don’t you run out of graft material to use?


Dr. 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.


Dr. Linda Austin:  Are there any medications that are useful for this illness?


Dr. Abhay Varma:  I’m, personally, not aware of any medication that can control nerve tumors or make one that is already there go away.


Dr. Linda Austin:  Anything on the horizon?


Dr. 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.


Dr. Linda Austin:  Is this genetic?


Dr. Abhay Varma:  It is genetic, yes.


Dr. Linda Austin:  So, if one parent has this disorder, what are the odds that a child will have it?


Dr. 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.


Dr. Linda Austin:  I see.  So, it just happens randomly?


Dr. Abhay Varma:  Yes.


Dr. 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?


Dr. 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.


Dr. Linda Austin:  Now, an easier situation for you, and, I’m sure, for the patient too, is a schwannoma.  What is a schwannoma?


Dr. 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.


Dr. Linda Austin:  What do you mean when you say eccentric?


Dr. Abhay Varma:  It means that it is growing away from the nerve, rather than wrapping around the nerve.


Dr. Linda Austin:  How long can those procedures take, to dissect that?


Dr. 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.


Dr. Linda Austin:  Where do these tumors typically arise?


Dr. 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.


Dr. Linda Austin:  If a person has one schwannoma, are they likely to get a second or a third?


Dr. 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.


Dr. Linda Austin:  Dr. Varma, thank you very much.


Dr. Abhay Varma:  You’re welcome.

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