In this section of Ask the Expert, you will find many of the most frequently asked general questions about CMT.
    • How can a doctor differentiate between carpal tunnel syndrome and the problems inherent in the hands and arms of CMT patients?

      Carpal tunnel syndrome does not appear to occur with increased frequency in patients with Charcot-Marie-Tooth. In the cases where I have diagnosed the condition in patients with CMT, I have found that it has been a result of cumulative or repetitive trauma. The diagnosis is a clinical one based on the occurrence of wrist and hand pain and numbness and tingling in the hand, intermittently, with activities, and at night. These symptoms are identical to those in patients without CMT. Because CMT disease causes weakness and wasting of all the intrinsic hand muscles and sensory deficits in all the digits, it is not possible to use those findings to confirm the diagnosis. However, it is possible to look for median nerve irritability at the wrist with provocative maneuvers. Finally, nerve conduction studies may be helpful in confirming the diagnosis by examining for a relative prolongation of the median motor distal latency as compared to that of the ulnar motor distal latency.
    • Is there a connection between CMT and fibromyalgia?

      Fibromyalgia (FM) and CMT are most likely unrelated disorders, but the symptoms of the two can overlap. For example, people who have CMT can have fatigue, muscle aches, pains and cramps, and lack of energy, which are common symptoms in FM. I am not sure the diagnosis of FM can be made with confidence in many persons who have CMT, unless the FM symptoms are quite pronounced, particularly in view of the fact that there is no general agreement about what FM is or its cause.
    • I have CMT. Is it okay for me to use a hot tub?

      I know of no medical literature addressing the effect of ambient temperature on peripheral nerve function in patients with CMT. If you want to use the hot tub, please first discuss it with your neurologist and consider trying brief exposures at lower temperatures to determine whether perceptible changes occur.
    • Can swelling of the feet be caused by CMT?

      Normally, swelling of extremities or joints is not a direct result of CMT, unless there is trauma to a numb joint. An evaluation for arthritis or even a systemic cause of extremity swelling, such as heart failure, would be in order.
    • Why do many people with CMT complain about very cold and/or very hot feet? Is there any treatment or procedure I can use to alleviate this problem?

      Cold feet and cold legs are frequent complaints in individuals with CMT. The only treatment is to use leg warmers and decrease exposure of the affected areas to cold weather. Poor tolerance to cold weather is probably due to the loss of muscle mass in the feet and legs. The loss of muscle mass due to nerve fiber loss is the reason for the wasting of the legs and feet in individuals with CMT. Decreased muscle mass decreases the amount of blood that goes to the lower limbs. The circulating blood is what keeps the normal temperature in the tissues. Bones, tendons and joints require less blood. Hot or burning feet is a sign of axonal neuropathy (loss of wiring of the nerves). Involvement of the axons is frequent in CMT. Pain due to the nerve damage in CMT responds to Neurontin (gabapentin) an anticonvulsant. This is a medication that needs to be prescribed, preferably by a neurologist.
    • I have a problem with food sticking in my throat and being uncomfortable when I eat. Is this something that CMT can cause, or is it likely to be something else?

      Although not a problem commonly associated with CMT, there have been reports of people with the disease having issues with swallowing. It is certainly not the norm, but muscles other than the arms and legs can be weakened by the disorder. Please see an expert CMT neurologist for further evaluation.
    • I am a U.S. Army veteran and served in Vietnam while the chemical known as Agent Orange (dioxin) was widely sprayed to defoliate the jungle. Could this exposure be responsible for making the pain and symptoms of CMT worse?

      Although there is a possibility that the Agent Orange exposure played a role, I don’t know of any evidence to support this theory. Nonetheless, the Veterans Administration accepts that early onset neuropathy may have been caused by herbicides. We know that patients with CMT are probably more sensitive to neurotoxins such as chemotherapy meds and may have more severe neuropathy if they have diabetes. So there is some logic to this contention but no specific proof as far as I know.
    • Does stress make CMT worse?

      Stress does not make the nerve damage worse and does not make CMT worse, but may make some symptoms like sleep, discomfort, pain, tingling and even balance worse.
    • Just wondering if donating plasma twice a week is detrimental to my health since I have been diagnosed with CMT disease. Any precautions I should be aware of?

      I am not aware of any reason why plasma donation should have any effects on CMT or vice versa.
    • Can birth control pills affect CMT?

      There is no clear evidence that birth control pills affect CMT nerves one way or another. There is ongoing research that progesterone antagonists might be helpful but not that these hormones are harmful to nerves. Obviously, the drugs carry other risks and side effects unrelated to CMT.
    • Can CMT cause noises in the ears?

      The auditory nerves can be affected in many forms of CMT. Most of the literature mentions this in terms of hearing loss. The noises that are mentioned would be consistent with the term “tinnitus,” which can occur when the auditory nerves are disturbed. So it is certainly possible that these noises are related to CMT. I would suggest seeing an ENT physician and/or audiologist and determine if there are abnormalities of the auditory nerve or if the problem is caused by something else.
    • I need to have an MRI with gadolinium, a paramagnetic contrast medium. Will this affect my CMT?

      The main risk is for patients with kidney insufficiency. I know of no relation to neuropathy unless they have mild kidney failure.
    • What is the difference between tomaculous neuropathy and HNPP (Hereditary Neuropathy with liability to Pressure Palsies)?

      Tomaculous neuropathy and HNPP are the same thing. Tomaculi are pathological features of some neuropathies, HNPP being the most common kind. Having one copy of the PMP22 gene, instead of two copies, is the typical cause of HNPP.
    • Are service dogs available to people with CMT?

      Yes, service dogs are available for those with CMT. Here is one site you can check out: www.cci.org/site/c.cdKGIRNqEmG/b.4010981/k.87A7/Apply_For_A_Dog.htm
    • Can radiation therapy cause a worsening of my CMT?

      I do not know of any well documented cases of radiation therapy causing worsening of CMT.
    • What’s the difference between CMT, MS and MD?

      CMT, multiple sclerosis, and muscular dystrophy are three completely separate and distinct diseases. Remember that our neuromuscular system really starts at the brain, which is the master computer, and sends signals to the motor (muscles) via the spinal cord (an intermediate connecting cable), which hooks up to the peripheral nerves (the connecting lines between brain and muscle). CMT is primarily a disease of the peripheral nerves (the connecting lines between brain and muscle). CMT causes weakness and impaired sensory perception because the signal can’t get to and from the brain to muscle and skin, among other things. The muscles shrink because they aren’t getting the proper signals, but the muscles themselves are not directly diseased per se. Muscular dystrophy is a disease of the muscle itself, which causes weakness of varying degrees (there are many forms of MD). Sometimes the heart is involved because it is a muscle too. The lungs can also be affected because the breathing muscles are weak (similar to CMT, although in CMT it is because the phrenic nerves are affected, which in turn weakens the diaphragm, our main breathing muscle). Multiple sclerosis is a disease of the brain and spinal cord. It can affect both movement and sensory perception and sometimes thinking processes..
    • Are there growth charts available for CMT?

      No, there are no growth charts for CMT. Children at neuromuscular or pediatric clinics routinely get standardized growth charts to determine whether head growth as a sign of brain growth is appropriate. These are not disease-specific.
    • Is trigger finger a common problem with CMT?

      Trigger finger is a common problem and probably not related to CMT.
    • Why and how does CMT skip generations?

      No, CMT does not skip generations. For some people, symptoms may be so mild that they go unnoticed. In some families, the type of CMT may present differently in different sexes. For example, with CMT1X females often have less severe symptoms than the males in the family, or be completely asymptomatic. Therefore, it may seem that the CMT is skipping a generation, but it is not. If a parent has CMT that has been genetically confirmed, any children can be tested when they are least 18 years of age and with appropriate genetic counseling. Testing children who do not have any symptoms for CMT is not recommended, as they might be stigmatized or treated differently. If a person does not inherit the condition from a parent, it cannot be passed on in the future. If your kids do not have CMT, your grandkids will not have CMT. There is one situation where CMT can seem to skip a generation. Recall that a person needs to have two copies of the gene with a mutation in order to have CMT and that all children of a person who has an autosomal recessive form of CMT will be carriers of the condition (one gene has the mutation, and one does not). If that child’s partner is a person who is also a carrier for the same condition, there is a one in four or 25 percent chance of having a child who is affected with the condition. In this situation, the grandparent and grandchild are affected, but the parent is not. Thus the CMT symptoms have skipped a generation, but the genetics behind the condition have not skipped. This is more likely to occur in relationships where family members marry each other, as it is more likely in these groups that the mutation in the gene has been passed on through carriers than in the general population.
    • Are CMT kids more susceptible to patella femoral syndrome?

      Patients with CMT are more likely to have joint pain, including knee pain, due to their abnormal gaits. Whether the knee pain is due to patella femoral syndrome is unclear. There is no consensus on the cause of patellofemoral syndrome. Contributing factors are thought to include overuse and overload of the patellofemoral joint, biomechanical problems and muscular dysfunction. Therefore, it is possible that patients with CMT may be prone to patellofemoral syndrome, but this will need to be investigated further before any association between the two is established.
    • Is the progression of CMT signified by neuropathic pain, as opposed to foot deformities?

      Dr. Scherer writes, “I think that these are quite unrelated. Neuropathic pain probably results from the spontaneous activity of injured pain fibers in the nerves; most foot deformities result from imbalances in weakened muscles.”
    • How common is CMT4?

      CMT Prevalence

      * For CMT4, the prevalence gets up to 40 percent in North Africa, where consanguinity is more frequent. The prevalence is about 20 percent in Spain because CMT 4A has a founder effect there.
    • Is fatigue common with CMT?

      Yes, fatigue is very common in people who have CMT, who expend far more energy to walk, stand, balance and do normal, everyday things than those who don’t
    • Is there a relationship between spasmodic dysphonia and CMT?

      As far as we know there is no link. However, if there is vocal cord paralysis related to CMT, then there can be dysphonia, which usually looks different than spasmodic dysphonia.
    • How does a person sign up for a CMT4 trial?

      Everyone with any type of CMT should join the Inherited Neuropathies Patient Registry, which will send alerts about current and future CMT studies and clinical trials: https://www.rarediseasesnetwork.org/cms/inc/registry
    • Is the progression of CMT signified by neuropathic pain, as opposed to foot deformities?

      What exercises can I do with CMT?
      Exercise is a very unique and personal experience. We recommend that you see a physical therapist for a personalized physical therapy program right for you. Our CMT physicians often recommend low-impact activities like swimming, yoga, biking, etc. The CMTA has an online series of articles and videos on exercise and CMT: https://www.cmtausa.org/living-with-cmt/managing-cmt/exercise/
    • I have two male grandchildren, both of whom have CMT. Both exhibit severe behavioral problems. Can CMT cause mental/behavioral problems?

      Generally speaking, the answer is “no” because CMT affects the peripheral nerves and not the central nerves.
    • Can CMT affect the internal organs?

      >Most cases of CMT do not affect the internal organs. While some rarer forms may include organ involvement, this is very uncommon. Breathing can be affected from muscle weakness but the lung tissue is not involved. Bowel function can be affected by weakness of sphincters, but that’s very uncommon.
    • Can CMT cause diaphragmatic weakness?

      >Peripheral nerves going to the diaphragm are affected in various types of CMT as these are large myelinated nerves. Abnormalities can be detected by nerve conduction studies, but they are not typically performed because many CMTers are not used to the technique and it is uncomfortable. In most people, nerve abnormalities do not result in weak or paralyzed diaphragms. Typically this occurs only in more severely affected patients. A few types of CMT, typically those that are axonal forms and severe, are more likely to result in paralyzed diaphragms. Remember that clinical abnormalities in CMT are usually length-dependent, causing problems at the far ends of the longest nerves, which are usually the hands and feet. In more severe forms, shorter nerves have problems at their far ends. This includes the phrenic nerve, which goes to the diaphragm.
    • Is CMT a type of Muscular Dystrophy?

      >No, CMT is not a type of muscular dystrophy. CMT is primarily a disease of the peripheral nerves, whereas muscular dystrophy is a group of diseases of the muscle itself. CMT causes weakness and impaired sensory perception because signals can’t get to and from the brain to muscle and skin, among other things. In the case of CMT, muscles atrophy because they aren’t getting the proper signals. When CMT affects breathing, it’s because CMT is affecting the phrenic nerves, which in turn weakens the diaphragm (our main breathing muscle). With muscular dystrophy, disease in the muscle itself causes weakness of varying degrees. Sometimes the heart is involved because the heart is a muscle. The lungs can also be affected by muscular dystrophy, causing breathing muscles to be weak.
    • Is it possible to have 2 different types of CMT?

      Please see a licensed genetic counselor (www.nsgc.org) to better understand your genetic testing results. The statistic is that about 1.5 percent of people will have two types of CMT. Not all variants are disease-causing. In many cases, the results of the genetic tests are often very difficult to decipher and seeing a trained CMT expert who also performs a physical exam is key for an accurate diagnosis.
    • Does CMT affect the autonomic nervous system?

      Not typically, but there are 2 exceptions: 1) In the case of Hereditary Sensory Neuropathies (HSN) also known as Hereditary Sensory and Autonomic neuropathies (HSAN), which fall under the CMT umbrella. 2) In the case of genetic neuropathies that have known autonomic abnormalities, such as Familial Amyloid Polyneuropathies (FAP). Patients with genetic neuropathies also typically have liver, kidney, and eye problems. We include these neuropathies loosely under the CMT umbrella because they are genetic. Note that FAP, a fatal disorder, is now being successfully treated by ASOs (from IONIS) and RNAi (from Alnylam).
    • What is CMT5?

      A diagnosis of CMT 5 can mean: 1) In most cases, CMT 5 is another name for Hereditary Motor and Sensory Neuropathy (HMSN) 5. A diagnosis of HMSN 5 used to be the common way to say that a patient had CMT and displayed upper motor neuron signs such as brisk reflexes. Upper motor neuron signs can occur in patients with several types of CMT, including some patients with CMT2A. It can even happen in patients with CMT1X. 2) There are rare forms of X-linked CMT, defined as CMTX5 with mutations in the PRPS1 gene. 3) Some patients with CMT2D (mutations in the GARS gene) have weakness, but not sensory loss. These patients are sometimes classified as having Distal Hereditary Motor Neuropathy type V (dHMNV).
    • >How does CMT1A affect hearing?

      There can be some effects of CMT-1A on hearing loss. To quote an abstract by Dr. Shy and his colleagues from 2015, “Audiologic results were consistent with hearing loss that is partly cochlear and partly neural in nature, particularly those with CMT1A.” An audiologist can test to determine the nature of the hearing loss, but there will be some overlap of age-related changes and effects of CMT.
    • Can CMT ever be listed as the cause of death on a death certificate?

      We know there are rare forms of CMT that are fatal. However, the cause of death would most likely not be CMT, because people die from breathing-related issues and cardiac arrest. The latter would most likely be listed as the cause of death.