Peripheral Nervous System: An Overview of the Peripheral Nerves

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Peripheral Nervous System:  An Overview of the Peripheral Nerves




Guest:  Dr. Abhay Varma - Neurosurgery

Host:  Dr. Linda Austin – Psychiatry


Dr. Linda Austin:  I’m Dr. Linda Austin.  I’m interviewing Dr. Abhay Varma, who is Assistant Professor of Neurosurgery here at the Medical University of South Carolina.  We’re going to be talking, today, about surgical treatment of the peripheral nerves.  And, first, just the basics, Dr. Varma, the peripheral nerves are, what?  How would you explain the difference between the central nervous system and the peripheral nerves?


Dr. Abhay Varma:  The peripheral nerves are the projections, basically, of the central nervous system into the peripheral parts of the body, carrying signals from the nervous system to the peripheral parts of the body and, also, signals from the peripheral parts of the body to the nervous system.


Dr. Linda Austin:  So, just to put it in really sort of simple language then, the nerves that go from the spinal column out through the torso, out through the chest, to the arms and the legs?


Dr. Abhay Varma:  And back from these organs into the spinal column.


Dr. Linda Austin:  Now, one of the types of surgery, I understand, that you do, so- called entrapment, or to relieve entrapment situations, what are some common examples of that?


Dr. Abhay Varma:  The most common is what we call carpal tunnel syndrome, where the median nerve is trapped by a fibrous band in the wrist and leads to numbness and, later stages, even weakness in the hands.  Less common ones being the ulnar nerve entrapment of the elbow, or even things like hemorrhagic parastatic, where there’s a nerve going into the thigh that gets entrapped in the upper part of the thigh, causing numbness in the front of the thigh.  Or rare ones like the thoracic outlet syndromes and suprascapular syndromes, etc.


Dr. Linda Austin:  So, then, basically, the nerve is getting entrapped in a band of fiber and that can happen in the wrist, in the thigh, in the elbow, sometimes up by the shoulder.  Okay, let’s take, maybe, one of the most common ones, the carpal tunnel syndrome.  What causes that?


Dr. Abhay Varma:  It’s a usually a band called the flexor retinaculum, which is present at the wrist.  This band runs from one wrist bone to the other, kind of creating a little canal through which the median nerve passes.  The median nerve supplies the outer part of the hand, the thumb and the first two digits, and, also, some muscles of the hand.  If this fibrous band gets thick, it narrows down the space in the canal through which the median nerve passes, causing pressure on the median nerve.  The person can, then, experience sensory symptoms with numbness or pins and needles sensations in the distribution of the nerve involving the thumb and the index and middle finger.  Symptoms are generally worse at night and sometimes can wake the person from sleep.  In later stages, if the muscles are also involved, it can cause thinning of the hand or even weakness of the hand.

Dr. Linda Austin:  Sometimes that happens because of overuse, is that right?


Dr. Abhay Varma:  That’s right.


Dr. Linda Austin:  Because of typing and so forth?


Dr. Abhay Varma:  Typing, or people who are involved in professions where there’s repetitive and forceful movement at the wrist joint, also, in certain medical conditions, like hypothyroidism, acromegaly, obesity, can even flare up during pregnancy.  But, usually, most commonly, now, we are seeing in folks who are using keyboards for very extended periods of time.  


Dr. Linda Austin:  Now, if someone who did experience in pregnancy, I know that sometimes you can treat it conservatively, to begin with, with just a hand brace, if it’s likely to be a temporary sort of thing.


Dr. Abhay Varma:  Yeah.


Dr. Linda Austin:  But, obviously, that doesn’t always work.  What’s the next level of treatment?


Dr. Abhay Varma:  Well, as you said, first, we have to look for an underlying cause that can be treated.  For example, if we know it’s a pregnant lady, then we, obviously, wait for the pregnancy to be over.  And, in most cases, it resolves on its own.  We also want to make sure that any underlying causes are identified and treated, like hypothyroidism, which is a problem with the hormones, or acromegaly, which is a condition where there’s an excess of hormones of a certain type in the body.  We have to look for those conditions, treat them and, also, while we are waiting for those conditions to be treated, symptomatically treat this condition by using a brace, like you mentioned. 


But if it doesn’t help and we have ruled out any underlying conditions and conservative treatment with a brace is not helping, the next step is, depending on a patient’s degree of discomfort, we pursue a full investigation with nerve conduction studies.  And if it is established and is not seen to be improving with conservative treatment, we will do surgery.


Dr. Linda Austin:  So, talk a little bit about that surgery.  First of all, the anesthesia, is it general or local?


Dr. Abhay Varma:  Most of the time, it is done under local anesthesia, unless the patient prefers to have general anesthesia.


Dr. Linda Austin:  And, how long does it take?


Dr. Abhay Varma:  The surgery itself doesn’t take more than 10 to 15 minutes.


Dr. Linda Austin:  Oh, that’s quick.  It must be a fairly simple surgery then.  What are you actually doing during the surgery?


Dr. Abhay Varma:  What we do is, depending on what kind of incision the surgeon is comfortable with, we make a small incision on the wrist that extends from the crease of the wrist into the hand.  Then we go down through the fat under the skin and identify the band that I was talking about and open that band and release the median nerve.  Once that is done, we make sure all the bleeding is controlled and we close the skin over it, without closing the band again.


Dr. Linda Austin:  And then I’m sure the patient goes home that day?


Dr. Abhay Varma:  Most of the time, patients go home the same day.  We observe them for a small period of time, maybe for about one hour or so, to make sure there is not bleeding and that they’re comfortable, the effects of local anesthesia have worn off, and then we send them home.


Dr. Linda Austin:  How long is the recovery period, until they can really fully use that hand again?


Dr. Abhay Varma:  Usually, it’s about, I would say, anywhere from three to six weeks, depending on the patient’s pain threshold and if there are any other issues.  Some patients tend to have a more inflammatory response following any kind of surgery.  Their incisions can be more swollen and painful.  In other patients, the healing is faster.  But, most of the time, from what I’ve seen, patients are able to go back to their activities by about six weeks. 


Dr. Linda Austin:  Now, if the carpal tunnel syndrome has been caused by something like too much keyboard use, too much typing, is it likely to recur?


Dr. Abhay Austin:  You mean, after surgery?


Dr. Linda Austin:  After surgery, yeah.


Dr. Abhay Varma:  If you’ve done a complete release of the flexor of the band, it’s unlikely to recur, unless there’s excessive scar formation in that area, or if the surgeon, for some reason, was not able to completely divide the band.


Dr. Linda Austin:  But, in most cases, the patient can go on, do well, play tennis, or whatever.


Dr. Abhay Varma:  Yes.  Once the pain and swelling of the surgery settles down, they can go back to their usual activity.


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


Dr. Abhay Varma:  You’re welcome.


If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection:  (843) 792-1414.


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