What is a Hereditary Neuropathy?
The term “hereditary neuropathy” is a mouthful, but it simply refers to a group of debilitating genetic diseases, which currently has no cure. In many cases, these diseases lie dormant, exhibiting no symptoms. In other cases, these diseases can impair the motor, sensory, and peripheral nerves of the hands and feet. Hereditary neuropathies can cause either the loss or disturbance of sensation in hands, feet, and limbs, and, over time may cause a wasting of the muscles, especially in the extremities.

There are many types of hereditary neuropathies. Symptom onset and severity differ, even within the same family. Nonetheless, hereditary neuropathies are all progressive; patients report losing strength, agility, dexterity, and even the ability to walk without assistance, making the diseases hard to accept on a psychological basis as well as a physical one.


What Is CMT?
Charcot-Marie-Tooth disease (CMT) is the most common hereditary neuropathy in the world, affecting millions worldwide; it is named after the three doctors who discovered it. There are four types of CMT; types 1 and 2 also have subtypes. CMT1A is the most common form of CMT, representing seventy-five percent of CMT patients. In some types of CMT, the myelin sheath that transmits nerve impulses to and from the brain is damaged, causing nerve impulses to be conducted more slowly. In other types of CMT, the axon itself is damaged and, although the conduction is nearly normal, the strength of the nerve impulses is reduced. All forms of CMT can result in muscle wasting and a decrease in motor and sensory function.


What Causes CMT?
CMT is usually genetic, affecting sixty to seventy percent of family members. However, recent testing has found the rate of spontaneous mutation to be at thirty percent. In all cases of CMT, a gene malfunctions and the result is CMT. In most types of CMT, the malfunctioning gene has been identified; however, the cause of the malfunction is unknown.


What are the symptoms of CMT?
CMT presents differently in each person and the severity of symptoms can vary greatly, even between members of the same family. However, here is a list of some common symptoms of CMT.
Very high arches
Hammertoes
Foot drop
Fatigue
Clumsiness
Awkward gait
Burning sensation in hands and feet
Pins and needles and numbness
Hand cramps & leg cramps
Loss of balance
Tripping and Falling
Weak ankles and other weaknesses in extremities
Decreased ability to stoop, squat, kneel, jump, climb, or run
Difficulty grasping and holding objects and opening jars and bottles


Who is affected by CMT?
CMT strikes millions of people worldwide, regardless of ethnic background or gender. It is estimated that at least 125,000 people in the United States suffer from Charcot-Marie-Tooth, although experts in the field think that number is much, much higher. The discrepancy stems from ignorance about Charcot-Marie-Tooth and hereditary neuropathies, not only on the part of the public, but also on the part of the medical community itself. Shockingly, many people suffering from Charcot-Marie-Tooth undergo years of testing before being diagnosed with the disease because most doctors cannot recognize the symptoms and accurately diagnose it.


What does CMT do?
With all types of CMT, the nerve signals are disrupted or weakened, resulting in severe muscle wasting and pain. Often, the muscle wasting happens unevenly, which causes deformity as opposing muscles atrophy at different rates. In many cases, the symptoms are mild and an altered gait can be corrected with a properly fitting orthodic. In more severe cases, people with CMT must wear braces or use a wheelchair to get around. In the worst cases, CMT can impair breathing and cause death.


Are there any treatments for CMT?
While there are no drug treatments for CMT, regular moderate exercise can help CMT patients preserve the form and function of their affected muscles. In addition, it is believed that early surgical intervention can help prevent deformity, greatly improving quality of life and mobility. Anyone with CMT or a genetic history of CMT should be vigilant about avoiding contraindicated drugs. As with any exercise or treatment program, people with CMT should consult their physician before embarking on any course of action.


How is CMT diagnosed?
Besides a genetic predisposition, there are a variety of physical indicators, such as foot deformities, fatigue, muscle weakness, and hammertoes that lead a patient to suspect that he or she may have CMT. Many forms of CMT can be diagnosed through a simple DNA blood test analysis. This is by far the least invasive way to learn this important information. CMT can also be diagnosed with an Electromyogram or EMG. This is a two-part test and can be slightly uncomfortable.


Can CMT ever be misdiagnosed?
CMT patients are often misdiagnosed with other neuromuscular diseases or told that they are crazy and that the symptoms are psychosomatic. This leaves them in medical limbo, unable to get the care and treatment they desperately need. This is extremely dangerous because many medications are contra-indicated and thus, very dangerous for people with Charcot-Marie-Tooth. Taking the wrong medication or supplement can accelerate or even initiate the progression of the disease, causing acute onset. For a list of contraindicated medications, please visit HNF’s website at 0000.


Where can I receive treatment?
In September 2006, HNF opened the Cedars-Sinai/HNF CMT Center at the Cedars-Sinai Medical Center in Los Angeles, CA. At the CMT Center, patients can explore treatment options and participate in relevant studies.