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Interviews with Professionals

Contents

Dr Gareth Parry answers basic questions

Sports and HNPP

Miscellaneous questions form e-mail support group

Question about HNPP and eye surgery

My Pregnancy and HNPP (personal story)

Dr Parry responds to Pregnancy issues from story above

Fatigue and HNPP

Which symptoms are HNPP?


October, 1997

We asked Dr. Gareth Parry, of the University of Minnesota, USA, who is doing research on HNPP to answer some questions about HNPP to help us understand it.

CMTInt: Dr. Parry, Thank you for agreeing to answer our questions about HNPP. Can you first describe HNPP genetically and genetically how does it compare to CMT? How is it inherited?
Dr. Parry: HNPP, like CMT, is inherited as an autosomal dominant trait. That is,50% of the children of an affected individual will inherit the gene and if the gene is passed on the recipient is at risk for developing the disease. One type of CMT (CMT1 a) is caused by duplication of a portion of chromosome 17 which encodes for PMP-22, an essential peripheral nerve myelin protein. HNPP results from a deletion in exactly the same region. Thus, the genetic abnormalities of CMT1 a and HNPP are mirror images of each other.
 
CMTInt: How common is HNPP?
Dr. Parry: HNPP is a common neuropathy. It probably has about the same prevalence as CMT - about 40 cases/100,000 population. However, many cases are undiagnosed or incorrectly diagnosed. In fact, many cases are diagnosed as CMT.
 
CMTInt: What are the symptoms of HNPP?
Dr. Parry: The commonest manifestation of HNPP is the abnormal susceptibility to the effects of pressure on the nerves which has given rise to its name - Hereditary Neuropathy with liability to Pressure Palsy. This susceptibility results in injury to nerves as they pass through restricted anatomical spaces in the body such as through the carpal tunnel in the wrist, giving rise to carpal tunnel syndrome, and around the inside of the elbow, giving rise to an ulnar neuropathy. It also results in significant nerve injury due to compression from outside the body. Such everyday habits as sitting with crossed legs and leaning on one's elbows can result in symptoms of numbness, tingling and weakness which may last for anything from 15-30 minutes all the way up to several weeks. This is an exaggeration of a phenomenon with which we are all familiar, but while a normal individual whose arm or leg "goes to sleep" will recover within a few seconds the HNPP patient's symptoms will be more severe and more protracted. Recovery is usually excellent at first but after many episodes, recovery is incomplete and some permanent residual remains.
The next most common manifestation is acute paralysis of one arm. This may occur in response to trivial trauma but often appears spontaneous. The entire arm becomes weak or even completely paralyzed and there may be some numbness and tingling. Recovery occurs over several weeks and is usually complete or nearly complete. It is unusual for these episodes to recur.
A significant number of families are thought to have CMT because they develop a progressive neuropathy with weakness of the feet and legs and lack, or fail to recognize, susceptibility to pressure. Careful examination of these families, including the EMG, usually shows features that make a clear distinction. These days, the genetic test can reliably distinguish the two conditions. It is important to make a distinction since HNPP usually is more benign than CMT.
Finally, many patients are undiagnosed because their symptoms are so minimal. This results in one affected member of a family being diagnosed with an acquired neuropathy and the inherited nature of the disorder is not recognized because relatives are not overtly affected.
 
CMTInt: Tell us about how HNPP is diagnosed. What symptoms should make a person or a doctor suspect that it's HNPP and not CMT or something else? And as a relatively rare disorder, what are the problems in getting it diagnosed?
Dr. Parry: Like all neuropathies, HNPP is diagnosed by careful clinical history and examination supplemented by electrodiagnostic studies (EMG). It is common for patients to present with symptoms and signs of carpal tunnel syndrome (pain, tingling and numbness in the forearm, wrist and hand). Transient episodes of numbness, tingling or weakness anywhere in the body, lasting for more than a few minutes should also raise suspicion of HNPP, particularly in a patient with evidence of a generalized neuropathy. In those individuals with HNPP who resemble CMT, these transient episodes may be the clue to the correct diagnosis. The EMG in HNPP is quite different from that in CMT. Both have conduction slowing which may be severe but in CMT it is diffuse, affecting all nerves to an almost identical degree while in HNPP the slowing is patchy and is particularly severe at sites prone to compression such as the carpal tunnel. The major problem in getting the condition diagnosed is lack of awareness of the evaluating physician. There needs to be a much wider awareness of HNPP amongst neurologists. At least one member of each family should have genetic testing to confirm the diagnosis. Some families (about 30% in some studies) have the characteristic clinical appearance of HNPP with a negative gene test. In such cases the diagnosis may need to be confirmed through nerve biopsy.
 
CMTInt: How is HNPP treated?
Dr. Parry: Unfortunately, there is no treatment for this neuropathy. Surgical nerve decompression may temporarily relieve symptoms of carpal tunnel syndrome but they frequently recur. Surgery is much less effective with other nerve compressions. Ulnar nerve transposition, which is commonly done for compression of this nerve at the elbow, is poorly tolerated and is contraindicated in these patients. Treatment of symptoms such as pain, and bracing for foot drop should not be neglected. In most respects the treatment of patients with HNPP is the same as CMT.
 

CMTInt: The last doctor I spoke with about HNPP said it is rarely as severe as CMT and yet I know people who's lives are significantly altered by HNPP. Is this common?

Dr. Parry: I agree that HNPP is usually much less disabling than CMT, particularly in terms of muscle weakness. However, HNPP does interfere with function to a significant extent. Some patients suffer significant pain. The need to avoid nerve injury from repetitive motion and to constantly change position can also make life quite difficult. Thus, although HNPP is generally less disabling some individuals are indeed significantly disabled by their disease.
 

CMTInt: Although it would seem genetically impossible, some people seem to have symptoms of CMT (muscle weakness, foot drop, hand problems) and HNPP (extensive numbness, tingling, etc.) As well. Could you explain this? Much of the literature seems to say that symptoms of CMT and HNPP can go together in person. I'm not clear on this.

Dr. Parry: As mentioned previously, some of our HNPP patients were identified because they superficially resembled CMT and yet had recurrent transient symptoms. I have never seen a true CMT patient develop these transient symptoms with such frequency as the HNPP patients. HNPP patients do develop a neuropathy eventually and in some people it may be the initial manifestation so the conditions occasionally resemble one another closely.
 
CMTInt: I have read in a few places that HNPP is also a Hereditary Motor Sensory Neuropathy (HMSN), yet we usually say that another name for CMT is HMSN. Can you explain this?
Dr. Parry: I do regard HNPP as one of the hereditary motor and sensory neuropathies since it is inherited and does have motor and sensory symptoms and signs.
 
CMTInt: Does the neurotoxic drug list also apply to people with HNPP?
Dr. Parry: We have less information about the effect of neurotoxic drugs on the nerves of patients with HNPP. However, I make the same recommendations that these drugs should be avoided if possible.
 
CMTInt: What kind of research is being done on HNPP? What are you doing?
Dr. Parry: I am studying several large HNPP families to try to better understand the phenotypic variability; that is the different ways the neuropathy affects different individuals despite having the same abnormality of the gene. We do not know why one member of a family should have recurrent pressure palsies while another a neuropathy resembling CMT and yet another have no symptoms. At the molecular level, people are trying to learn how the gene controls myelination of peripheral nerves and what happens when the gene is abnormal.
 
CMTInt: What do you see in the future for people who have HNPP?
Dr. Parry: As there is a wider appreciation of this curious neuropathy, I see patients being better understood when they complain of recurrent transient symptoms. They will be less likely to be ignored if there is a better appreciation of the disease. I would also hope to see less unnecessary and sometimes harmful surgery done on HNPP patients who are diagnosed with simple compressive neuropathies.
 
CMTInt: How can CMTInternational help?
Dr. Parry: There is a great need for wider dissemination of information about HNPP to both physicians and patients. CMTInternational can, through its newsletter and other means of communication, help in this important way. It can also serve as a conduit for providing information about the disease to patients who are often puzzled as to why they do not seem to be the same as other CMT patients.
 

CMTInt: And finally, what suggestions would you give to a person with HNPP who is seeing a doctor, such as an internist, who doesn't know anything about this neuropathy?

Dr. Parry: I think organizations like CMTInternational need to take the lead in providing patients and physicians with the information they need about this disorder. If a patient with HNPP has a physician unfamiliar with the disorder, he or she could provide the physician with educational material from CMTInternational. I think that material could contain names and addresses of neurologists who are expert in the disorder as well as information about its effects. In this way, individuals would not be deprived of information and appropriate management of HNPP.

CMTInt: Thank you for this, Dr. Parry, and please keep us updated on your work in HNPP research.

Linda Crabtree, Executive. Director, CMTInternational

 Reprinted with permission from Vol. 14, No. 5, 1997 CMT Newsletter, publication of CMT International,.


A question answered about sports and HNPP

Question: My son who is seven was diagnosed in October 1997 with HNPP. He had an episode of sudden onset foot drop in his left foot. It took about eight weeks to return to normal. We really aren't sure what caused it, but we think he slept on it wrong.

Since this occurred when he is so young, do you think he will have a severe case? And as this a progressive disease, does it happen easier each time? what about sports for him? He is currently on a soccer team that will resume play in the Spring. His doctor is at Children's hospital in Pitttsburgh and he said not to restrict him, but it is hard not to worry about it.

Dr. Gareth Parry, Professor and head of the Departmetn of Neruology at the University of Minneosta Medical School and our advisor on HNPP answers: "there is no evidence that indicates that early onset HNPP necessarily leads to more severe disease. Often, there is no obvious precipitating even although "sleeping funnny" may be an explanation for some of these episodes.

You say this is a progressive diseae and ask does it happen easier each time? Unfortunately, this is a progressive dsease over a lifetime but the disability is usually not severe. The episodes do not occur with progressively less severe prescipitating events. Eventually weakness and other neurological problems become permanent but they are usually mild. Affected individuals nearly always live active and productive lives with only minor restrictions.

You asked about sports for him. That is one of the the most difficult questiosn that I am asked. It is hard to deprive a child of an activity which he enjoys. On the other hand, he is more suseptible to developing episodes of weakness associated with minor trauma and any sport will subject him to episodes of minor trauma. I therefore recommend that contact sprots be avoided and since soccer inevitably results in some physical contact, I feel that it too should be avoided. However, I have many pateints who have ignored my advice, including one who played American football, and who suffered no ill-effects. It may be that I am too conservative. I recognize that my answer concerning sports is a bit wishy-washy but it is a very difficult area about which we have insufficient information to give definite guidelines.

Reprinted with permission from CMT International Volume 15, Number 1, Febraury 1998

 


For this issue of the newsletter, we had the HNPP e-mail support group pose questions to Dr. Parry. Dr Parry replied. "The questions are tough and I hope the replies are helpful."

 

Question: What should you do if you have symptoms and test negative?

Dr. Parry Replies: (Posted on website: We know that only about 80% (70% in some studies) of HNPP patients have the deletion in chromosome 17. A few of those negative cases have had identified point mutations of the gene. Thus it is certainly possible to have the disease with a negative gene test but it is unusual. The first thing to do is to establish a diagnosis which would require careful examination, EMG studiesand nerve biopsy. If all of these indicated the HNPP diagnosis and the family is large neough, a search could then be made for other genetic abnormalities.)

Dr. Parry Replies: I think that this is already covered about as well as I can at this stage. To perhaps slightly change the wording I would say that the first thing to do is to establish that the patient has a tomaculous neuropathy (one of the other terms for HNPP). This can only be done with nerve biopsy. If the nerve biopsy is normal and yet the patient has symptoms and signs That suggest HNPP then another explanation needs to be sought. For example, CNS demyelination may produce transient neurological symptoms that resemble HNPP. If the nerve biopsy is positive but the genetic testing is negative then a search can be made for other genetic abnormalities as outlined previously.

Question: Since this is such a newly discovered disease, how can anyone be sure that we will always be able to take care of all of our personal needs? When I had drop shoulder, taking care of personal needs was a challenge.

Dr. Parry Replies: This is not a newly discovered disease. We have known about for about 50 years. What is new is the realization that it is far from rare. However, we do have a lot of information about the course of the disease from those patients who were diagnosed many years ago. It is certainly very difficult for patients to take care of their personal needs when they are in the midst of an attack, particularly if there is severe weakness of an arm. Also, since the disorder is overall progressive we know that some patients develop progressively increasing difficulties. However, we can say that for most patients the course is one of very slow progression with interspersed episodes of more severe disability from which recovery (complete or partial) almost always occurs. Clearly there are both severe and mild cases but the disease is usually a nuisance but not a major disability.

Question: If HNPP affects all of the nerves in the body except for the central nervous system, why should we not assume that our internal organs will be affected?

Dr. Parry Replies: The nerves that are affected are those that are insulated with myelin. The nerves that control our internal organs are mainly unmylenated and therefore are unaffected by HNPP.

Question: What does 'low amplitudes' mean on the EMG? For both the sensory and motor parts

Dr. Parry Replies: Low amplitude simply means of small size. When the nerve is electrically stimulated we can record a response from the nerve itself (sensory) or from the muscle it supplies (motor). The response we record has a certain size, that should fall within a well defined range. If the size of the recorded response falls below that range we refer to the response as "low amplitude".

 Question: You have explained what low amplitude 'means', now what is the 'significance' of the low amplitudes on the EMG? Or can you not pick out one part of the EMG and say anything about it?

Dr. Parry Replies: It is important to view the EMG like a physical examination. There is no one part that can be interpreted without knowledge of all the parts. In simple terms, low amplitude means loss of axons while demyelination causes slowing of conduction. Loss of axons is more serious because it indicates more severe damage with reduced capacity for recovery.

 

Note: This question has been taken from the HNPP website and is referenced in the question following this one.

Question: Should Hnpp patients have annual checkups...I mean, I wonder what they would do...just tell me my hands are the way they are because of HNPP and smile and then I go home? I just never made any more appointments because I figured everything was useless....

Dr. Parry Replies: This is a very fair question and one for which there is no definite answer. I believe that the doctor-patient relationship is a partnership and it is important that the doctor knows how each individual patient responds to his/her disease. I ask all of my neuropathy patients to see me at least annually so that we can both keep in touch so that when I really do need to do something I know the person as an individual and I also know what the status of their disease has been. We as physicians cannot learn about how "untreatable" diseases such as HNPP affect our patients unless we see them from time to time. Then we are criticized for not being understanding when our patients tell us of there complaints because we often do not understand. It is only by seeing patients on a regular, though usually infrequent, basis that I have learned what I now know of this annoying and occasionally disabling disease.

Question: What possible events are you thinking about when you suggest that a person be followed by a neurologist in case things come up?

Dr. Parry Replies: I am thinking about things like acute brachial paralysis or subacute generalized neuropathy as has been described. If a patient has one of these less common but more serious and definitely scary complications of HNPP it is useful for the doctor to know what the status had been. However, another big part of it is maintaining the doctor-patient relationship. I like to know my patients and if I don't see them at least once and preferably twice a year I cannot really know them. They come to the office as strangers and my ability to serve them is therefore reduced.

Question: What kind of follow up test should be done to test the progression of HNPP, if any test and how often? example EMG's. OR do we just do normal neuro follow-ups every year?

Dr. Parry Replies: My feeling is that repeat EMG's are sometimes needed when there is an acute episode but even then not usually. If I have someone who is stable generally perform a semiquantitiative neurological examination (strength in a standard group of muscles, sensation and reflexes) and ask a series of questions about things like tripping, turning ankles, difficulty with stairs, difficulty using keys or opening tight screwcaps as indicators of progressive neurological problems. I also ask about the frequency of episodes, were they sensory, motor or both, is there pain. Finally, I have learned to ask whether the patient has any observations or questions. I need to continue to learn about this disease and I can do that in part by listening to my patients.

Question: Would you add anything to your answer if the patient seems to be steadily progressing (as much of the group is)?

Dr. Parry Replies: No I don't think that progression or absence thereof would make a difference to my approach. I do tend to see progressive patients more often but the approach is pretty much the same. Of course, with some patients I spend more time listening and talking than examining. It all depends on individual needs.

Question: Talk about the elbow surgery and the ulnar nerve at length (Transposition or moving of the ulnar nerve). We are getting many different opinions from doctors. Don't have surgery, it's too late, have to watch it, we may be forced to do it, it is not time yet. What makes it too soon, too late or just right for surgery? Is it symptoms or the EMG and if the EMG then what specifically? Some have had the surgery with success and others have had same or increased problems. You have stated your opposition to moving the nerve. Can you explain why? Just what is the thinking and the controversy about surgery?

Dr. Parry Replies: There is very little data on these issues in the literature to provide us with guidance. Therefore I am relying on my experience with dozens of patients and conversations with many more, both directly and through the questions posed by the group on the internet. I have had several patients who have had disastrous outcomes from ulnar nerve transposition. The nerves in HNPP patients seem to be sensitive to stretch injury and manipulation during surgery. It is not possible to move the ulnar nerve to the front of the elbow without doing some damage and it is occasionally severe. Even in non-HNPP patients there is very little evidence that ulnar nerve transposition is any better than simple decompression unless there is a major elbow deformity. Thus, I am not vehemently opposed to simple ulnar decompression at the elbow but my experience has lead me to be extremely wary of transposition. Even with something as simple as carpal tunnel decompression, the benefit may be only short lived - symptoms tend to return in 2-3 years. I do recommend carpal tunnel decompression if there are significant symptoms because it is very safe surgery but I warn people that the symptoms may return. I have seen one patient who had bad outcome from CTS surgery, probably because the surgeon was inexperienced. I would not allow any of my patients to have surgery unless the surgeon was aware that the patient had HNPP and the surgeon was very experienced. I would not allow my HNPP patients to have arthroscopic CTS surgery.

Question: My question for Dr. Parry is: Is there any way that HNPP can be the cause of my constant head pain for the last 25 years?

Dr. Parry Replies: I think it is unlikely although I am learning that there may be more manifestations of the disease than any of us has been aware. There are nerves coming up the back of the skull from the neck and I guess it is possible that the increased susceptibility to compression may affect these nerves and lead to headache.

Question: What is known if anything, about HNPP and head pain, such as my glasses hurting my head, and nose...a rubber band in my hair, pain upon brushing hair, pain from hair curlers. And is anything known about the eyes and HNPP?, this is a problem in my family. Along with some members having headaches. Also I have pain in the nerves of my teeth, even tho they are perfect, I do suffer when I floss. Neurontin seems to help.

Dr. Parry Replies: As mentioned above there is not much known about head pain and HNPP. It is quite surprising how seldom the cranial nerves are affected. I have had patients complain that they get numbness from a head band or a tight cap. One of the problems is that headaches are so common - 85% of people suffer from some headaches. Thus it is difficult to know whether headache in an HNPP patient is related to their disease or to some other condition such as stress. The eyes are not directly affected; or at least not the vision. I was not aware of problems with the teeth until Maureen brought it to my attention from discussions on the internet. It seems that tooth pain is more common in HNPP patients than in the general population. I do not know what its basis might be. Perhaps we need to be more sensitive to the possibility that various cranial nerves may be involved and look harder for it.

 Reprinted with permission from CMT International Vol. 14, No. 5, 1997


HNPP and eye surgery

Linda here - An HNPP reader asked if anesthetics given during eye surgery could harm her. I suggested pressure during the operation would be of more concern than the actual anesthetics as during my cataract surgery it seemed as though there was a great deal of pressure during the anesthetizing period. Make sure the surgeon knows that pressure can be a problem.

Dr. Gareth Parry replies: "I agree that there is absolutely no risk from the drugs that would be used in eye surgery. There is a negligible risk to the surgery itself. Eye surgery is done with microscopic instruments and there is no pressure on the face or surrounding areas."


My pregnancy and HNPP

Lori Brown, CA, U.S.A.

Being diagnosed with HNPP was a real blow. So far, doctors don't have any answers as to its progression. There is no cure for HNPP and there is a good chance my children will have HNPP. The uncertainty of that possibility drove me to have my five- year-old son and two-and-a-half year-old daughter tested for HNPP and make arrangements to have my unborn baby boy tested using his cord blood at birth. I am worried about the future of my children's health because right now there is no cure or good treatment being offered to HNPP patients.

I had to stop taking all the medications that were helping me to deal with the nerve pain and numbness due to my pregnancy. As a result of this and the weight and pressure from the baby, it is causing my HNPP to flair up. I decided after getting brushed off by numerous doctors that I need to take charge of my health care. I started getting on the Internet and looking up anything and everything I could find on HNPP but I learned there is not a lot out there. I joined an e-mail support group that has given me the best advice and support that I was needing. I am able to get "real life" information on HNPP, not the "pain-free no big deal" disease I was told about by the doctor who diagnosed me after two muscle and nerve biopsies and DNA testing.

Pregnancy is a big unknown with HNPP. The doctors I am seeing have no idea how to treat me and seem to be afraid of me. They are afraid of the unknown. I am having a lot of nerve pain that shoots up my legs into my back and hips. I am having a lot of virtually continuous episodes of numbness and weakness in all four extremities. I am also having numbness in my face which is causing my mouth to drop on one side. My ankles are giving away and I am falling quite a bit, hurting my ankles and endangering the baby, so the doctors gave me a walker and ankle support braces. The only problem with that was the walker caused my arms to go numb. I now have a wheelchair and am dependent on others to take me to the stores and doctors.

At 24 weeks pregnancy, I started having contractions and dilating and was put on bed rest. The doctors are in conflict over this issue as well. One doctor says that my HNPP nerve irritation could be causing the uterine irritability which in turn causes cervix changes. Another doctor states that can't be the case. Who is right? Since there is no real research on HNPP out there, no one knows for sure. This disease needs to be researched in great length to try to get us some answers. I do not want my children to have the same uncertainty that each day brings. Will I be able to walk today or will I be able to hug my children today or hold them. It is hard!

I am only 26 years old. I showed signs of this disease when I was a child but nothing was ever pieced together until after the birth of my daughter over two years ago. My "pregnancy carpal tunnel" did not go away after pregnancy so I went for some nerve conduction studies which showed problems in all four extremities. Needless to say, the doctors were stumped for a while and just wanted me to go on pain pills and steroids for the rest of my life. I did not accept this answer. I pushed to get a new doctor, and he did a lot of testing until finally the DNA test came back HNPP. It was a relief to have an answer but just not the answer I wanted to hear after learning of no treatment or cure.

I am having a hard time adjusting to the difference in quality of life that I have now. I want to be able to go shopping all day with my mom like I used to be able to do. I want to be able to walk my son the mile to school like his other friends' moms do. I want to be able to hold and carry my daughter when she is crying. I just can't do it anymore and that hurts more than the HNPP does.

I was always so independent and did not back down from challenges. I am not backing down from this one. I am just going about it differently by telling my story to whoever will listen, trying to educate doctors on what HNPP is like, and answering any questions thrown my way about HNPP. I feel it is my responsibility to my children to do anything and everything in my power to try to get doctors to listen and learn about HNPP.

My husband and I are anxiously awaiting the DNA test results on my children. The unknown is the worst part of this disease. If you take nothing else from my story, please take this with you. Please educate yourself, take control of your own medical care, get second opinions, and find a good support group you can depend on.

 Linda here - We'll print Dr. Parry's reply to Lori here and then update you on the baby.

 

Dr. Gareth J. Parry, Neurologist, Auckland Hospital, Professor of Neurology, University of Minnesota answers: Lori has experienced many problems with which HNPP sufferers can surely empathize. These include delayed diagnosis, lack of knowledge about the disease on the part of most doctors, the tendency of neurologists to make light of the disorder, and the uncertainty about the future. I will comment on each of these issues briefly.

1. The diagnosis is difficult to make because the early symptoms are often so non-specific. It is easy once you think of the diagnosis because the DNA testing is now so reliable. However, that testing is often delayed, as happened to Lori. One of the curious features of this disease is that a family history is often lacking even though it is inherited in an autosomal dominant pattern, and therefore, statistically, 50% of the members of large families should inherit the gene for the disease. In many cases we have found that there is indeed a family history but symptoms have been attributed to other conditions such as carpal tunnel syndrome. This lack of an obvious family history of the disorder contributes in a major way to the delay in diagnosis.

2. HNPP is widely considered to be a rare disorder. However, evidence is emerging that it is one of the commonest of the inherited neurologic diseases. Many cases are undiagnosed while others are misdiag nosed. The great majority of non-neurologists have never heard of the disorder and even neurologists are very vague about it. One of the most effective ways to educate the doctors is through the patients who suffer the effects of HNPP. To do this, we have made use of CMT International and CMTA to disseminate knowledge to patients who can then take it along to their doctors. There is also a very good Website (www.hnpp.org) that has been set up by one of my patients, Maureen Horton, that allows patients to get more information on the disease. Hopefully we will be able to get a better appreciation of the disorder through this mechanism. I also agree with Lori that more research needs to be done. Up until now, most of the work has focused on determining the genetic basis for the disorder. Now we need to try to understand how the abnormality in the genetic code leads to the symptoms and, most importantly, come up with a way of treating the problem.

3. It is true that HNPP is usually a mild disease that is a nuisance but not much of a disability. However, as Lori clearly illustrates, it can result in true disability. Pain is one of the most under-recognized features, and some of my patients have had the same experience as Lori, being told that this is a "pain free, no big deal disease." The effects of the disease on each patient are as unique as the individuals themselves. Once again, the way to reverse this common misconception is through education of both patients (so they can tell there doctor) and of the doctors themselves.

4. The uncertainty about the future is one of the most difficult issues to deal with for any patient with an inherited disorder. As for Lori, most patients have as much concern about their children as they do about themselves. I have no simple answer. I can only give the reassurance that the great majority of patients live long and productive lives with their disorder causing only minor annoyance. This does not help the minority for whom this is not true. I would say that I've never seen a patient die of the disease or even end up in a wheelchair. The other attempt at reassurance is that the disease affects different family members very differently, and just because Lori is having so many problems, it may not affect her children in the same way.

While I would not criticize her decision to have her children tested, it is not what I would have recommended. This is a very personal decision, but from my perspective, I would be concerned about parents being overprotective of their children if they knew that a child carried the gene. Furthermore, while there is no treatment for the disease, there is little to be gained from knowing the diagnosis. I generally recommend testing in the late teens, at a time when people are making life decisions. I would reiterate that this is a very personal and individual decision and one that should be made after careful discussion within the family and with a knowledgeable neurologist.

 Reprinted with Permission from CMT International


Fatigue and HNPP

Question: Dr. Parry, I have read much about you and by you. I have also learned a lot from Maureen Horton, her Website, and the support group which I recently joined. My reason for contacting you today is to ask you your opinion on something.

I recently had an appointment with my neurologist and I was less than enthused with his responses and attitude. He told me that my fatigue is NOT a symptom of my HNPP and not to blame all my problems on my HNPP. I realize that you know nothing about my particular circumstances or symptoms, but I wonder if I could get your reaction to his remarks in general? I have read a lot about people with HNPP and CMT who do struggle with fatigue, and I was shocked at his comments.

Thank you for your time, and thank you for everything you have done so far for people with HNPP.

Dr. Gareth J. Parry, Neurologist, Auckland Hospital, Professor of Neurology, University of Minnesota, answers: Let me start by saying that I do agree with your neurologist up to a point. That is, it is important not to attribute all of your complaints to HNPP. There is a great tendency in any chronic disease to ascribe any complaint to that disease and not to sufficiently consider other possible explanations. However, it has been my experience that all patients with neuromuscular disease suffer from fatigue to some extent. Even if there is no obvious weakness of the muscles, the chronic nerve damage that results from conditions such as HNPP and CMT may mean that the patient needs to work harder to achieve normal strength than someone with the full complement of nerves. I tell my patients that it is important to pace oneself to minimize this fatigue but it is difficult to avoid it entirely. Of course, there may be other reasons that your doctor is reluctant to attribute your fatigue to the HNPP but it certainly is both possible and common for HNPP patients to suffer from fatigue. I hope this helps.

 Reprinted with Permission from CMT International


Which symptoms are HNPP?

A question for Dr. Gareth Parry from Maureen Horton, Minnesota:

Question: In the last issue of the CMT Newsletter, you talked about educating patients so they could educate their doctors and spread the word about HNPP that way. You also replied to a person with HNPP that "it is important not to contribute all of your complaints to HNPP. There is a great tendency in any chronic disease to ascribe any complaint to that disease and not sufficiently consider other possible explanations". This is an important lesson for not only the patient but all health care providers as well. I don't know about others, but when I see any doctor who doesn't know about HNPP - a neurologist or not - they are so freaked by this unknown disease, that I feel like I am in the drivers seat. I feel I could tell them about anything I wanted to and they would believe me. If I thought my gastrointestinal problems or a tooth ache or an ingrown toe nail were related to HNPP, they would believe me. I think they would give me anything I asked for. It can be a scary position to be in where I know more than the doctors I am going to for advice. How do you get the doctors to understand the basics of the disease so they know how to help you? And what would you say about the all too frequent times when the doctors don't want to have anything to do with the HNPP, always deferring to the neurologist? There have been several instances in the e-mail support group of people reporting that their doctor/ neurologist/ specialist said that their blood pressure, eye, digestive, etc problem was due to the HNPP. So it is not only the person with HNPP thinking everything is related to HNPP, but their doctors as well. It is my understanding that we really don't know yet if HNPP causes problems outside the peripheral nervous system. When is it okay to think maybe it IS related to the HNPP and when is it not? Since all of us with HNPP need to be the ones spreading the HNPP story, how do we handle this situation? When do we push for more testing to find other causes and when do we go along with them?

Dr. Parry answers:

Several difficult but very important issues are raised. The simplest answer would be to ensure that all HNPP patients are regularly followed by a neurologist with a special interest in neuropathies but obviously this is not realistic. I would take the position that unless a problem clearly has a neurological basis then it should not be attributed to HNPP. The only symptoms that I would attribute to HNPP largely without question would be numbness, paresthesias (pins and needles, tingling, etc) and weakness. Pain is more common that has been generally recognized but even pain I would not automatically attribute to HNPP.

This does not mean that a variety of other symptoms cannot be caused by HNPP. We are learning, through listening to our patients, that many symptoms seem to be more common in HNPP patients than in the general population or even in patients with other neuropathies. However, we do not yet know whether this is just coincidental. Therefore, I would still regard any symptom other than those listed above as probably unrelated to HNPP and therefore needing of investigation into alternative explanations.

Gareth J. Parry, Neurologist, Auckland Hospital, Professor of Neurology, University of Minnesota

Reprinted with Permission from CMT International, Vol 17 Number 5, Novemeer 2000


Last Updated 12/01

 

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