Marie Charcot Tooth Disease: A Genetic Problem

Even though the condition is called Marie Charcot Tooth disease, it actually has no connection with any type of tooth problem.

The name was derived from the three doctors who came across the problem. Marie Charcot Tooth disease or CMT disease is a rare genetic disorder that affects the peripheral nerves. As a result, individuals will display a number of traits and characteristics that will hinder their ability to perform usual tasks. The severity of the problem can range from mild to severe. Here is a general look on the condition.

Defining Marie Charcot Tooth Disease

Marie Charcot Tooth disease, even though considered rare in some aspects of medicine, is one of the most common inherited neurologic conditions. People who have the problem will show a number of traits and inherited neuropathies.

Dr. Jean Martin Charcot from France and Pierre Marie came upon the condition back in 1986 when they noticed muscle wasting and weakness in the legs. Their first published report described CMT as peroneal muscular atrophy. In the same year, Howard Henry Tooth also discovered the disease in the United States and called it peroneal progressive muscular atrophy. The symptoms were adequately presented by Tooth to neuropathy and not myelopathy.

Over a decade later, Hoffman also found a special case with the same symptoms and thickened nerves. This was referred to as Hoffman disease and is currently known as Charcot Marie Tooth Hoffman disease. Over five decades later, Marie Charcot Tooth disease was categorized into two types: CMT 1 and CMT 2. The division was based on the physiologic and pathologic features of the disease. The genetic cause of the disease also gave physicians a way to categorize it further. When genetic testing was introduced, many diseases under CMT syndrome were easily recognized.

Pathophysiology of Marie Charcot Tooth Disease

Marie Charcot Tooth disease is described as a heterogeneous collection of genetic problems with very close or associated signs and symptoms.

The disease has different subdivisions namely CMT Type 1 or CMT 1, CMT 2, CMT 3 and CMT 4 or CMT X. CMT type 1 is a special form of the disease which is a condition of peripheral myelination abnormality based on the mutation of the PMP22 or peripheral myelin protein-22 gene. Changes in the gene happen to about 5% of those afflicted with Marie Charcot Tooth disease. The changes are caused by an irregular myelin that will easily break down and demyelinate.

The transmission of signals as well as the interruptions in the proper conduction of sensory and motor nerves will lead to numbness and weakness of the muscles. Schwann cells will also spread and create remyelination groups. A thick layer of irregular myelin will form surrounding the peripheral axons due to the repetitive cycles of sheath formation and removal. This leads to the onion bulb appearance among those with Marie Charcot Tooth disease.

Other Types of Marie Charcot Tooth Disease

The CMT 2 is a neuronal condition and is different from the first type which is a demyelinating problem. The second type will lead to peripheral neuropathy via a direct death of the axon and degeneration. The third type or CMT 3 usually occurs during the infancy stages. It leads to severe demyelination with motor skills slowing down. It is more severe than the first type.

Some of the other things that doctors will notice up close include the thinning of the myelin surrounding the nerve and the marked segmental demyelination. This is seen well during tissue examination. The third type is also called Dejerine-Sottas disease. The fourth type or CMT 4 or CMT X is a demyelinating neuropathy.
Marie Charcot Tooth Disease Diagnosis and Assessment

Marie Charcot Tooth disease or CMT is first determined by having the patient go through the standard assessment. The doctor will ask the patient about his family background, medical history and other previous signs and symptoms. Neurological and related tests will also be done. The doctor will want to know the presentation, severity and time of the presentation of symptoms and if other members in the family also share the same condition or symptoms.

Muscle weakness will be observed in the legs and arms. The physician will also check for other common signs like muscle wasting, thinning of the legs, feet abnormalities, muscle weakness and loss of sensation. Orthopedic symptoms will also be checked like hip dysplasia and scoliosis. One of the common conditions that can be found among patients is nerve enlargement or hypertrophic nerves that are visible on the skin. This is due to the thickening of the myelin sheaths.

More Diagnostic Procedures for Marie Charcot Tooth Disease

As soon as the physician notices the presence of CMT, he may ask the patient to undergo electrodiagnostic examinations. The approach will cover two approaches namely electromyography or EMG and nerve conduction studies. During the nerve conduction studies, the electrodes will be positioned on the skin over a sensory or peripheral motor nerve.

Minor electric currents will be sent to determine how the nerves are functioning and how the patient responds to the current. The impulse actually stimulates the motor and sensory nerves and provides adequate information that will help physicians come up with the proper diagnosis. EMG will involve putting a needle electrode through the skin to check the bioelectrical muscle activity. Some changes in the readings will also indicate degeneration of the axon.

Genetic Counseling for Marie Charcot Tooth Disease Patients

Some people wish to undergo genetic testing if they believe that they have Marie Charcot Tooth disease or CMT of any type. Genetic testing will help determine where they acquired the condition and if they can also pass on the problem to their offspring. Genetic counseling is advised for patients who are expecting to have children in the future.

The doctor or counselor can provide risk assessments as well as indicate the proper methods that will hopefully reduce the risk and occurrence. Genetic counseling is also very helpful in helping families and patients cope with the debilitating effects of the disease. Marie Charcot Tooth disease can be prevented in some ways by staying prepared for the genetic tendencies.