What is Charcot-Marie-Tooth Disease?
Charcot-Marie-Tooth Disease (CMT) is a genetic condition that is characterized by mutations that cause damage to the peripheral nerves that run outside of the brain and spinal cord. CMT was named after Drs. Jean-Martin Charcot and Pierre Marie of France, and Dr. Henry Tooth of the U.K. who jointly discovered it in 1886.
CMT is one of the most commonly occurring hereditary neurological disorders. It affects approximately 2.8 million people worldwide. According to the Hereditary Neuropathy Foundation, the disease is typically passed from parent to child, however there have been instances where a patient develops CMT due to a random mutation in their own genes, rather than inheriting it from a parent. Symptoms of the disease usually start presenting in adolescence or early adulthood. The condition (in most cases) develops gradually form there.
What are the types of CMT?
There are multiple sub-types of CMT, categorized primarily by whether the axon or the myelin sheath of the nerve is affected. (The axon acts as a transmitter, sending electrical information and impulses between the brain and the limbs. The myelin sheath acts as a protective insulating layer around the axon, that helps to make sure that the integrity of the electrical impulses is maintained.)
CMT types are further categorized based on inheritance pattern, how the genes are affected, age of onset, and predominant symptoms. Some of these sub-types have been given their own names. For example, Dejerine-Sottas Syndrome is a severe form of CMT that starts in early childhood, and Roussy-Lévy Syndrome is a form of the disease typified by tremors. CMT has also been known as HMSN (Hereditary Motor and Sensory Neuropathy), or as Peroneal Muscular Atrophy. The table below provides an at-a-glance comparison of the major forms of the disease:
(aka Dejerine-Sottas disease or Early-onset CMT)
|Cause(s)||Damage to the myelin sheath covering the affected nerve(s)||Damage directly to the nerve axon||Defects in the myelin sheath that protects the axon||Defects in the myelin sheath that protects the axon||Mutations in the connexin 32 gene on the X chromosome cause damage to the myelin sheath surrounding the nerve|
(Inherited from one parent. One copy of a mutated gene causes the condition.)
(Inherited from two parents. Two copies of a mutated gene cause the condition)
|Autosomal- recessive (or in fewer cases autosomal-dominant)||Autosomal- recessive||X linked-dominant
(Mutated gene is located on the X chromosome and passed from mother to son
|Occurrence||Common||Less common than type 1||Extremely Rare||Rare||More common in men|
|Onset||Childhood to adolescence||Generally during adolescence, but age of onset varies more than with CMT1||Infancy: by or before the age of 3||Infancy or childhood||Late childhood or adolescence|
|Weakness, atrophy, and loss of sensation in the lower legs, feet, forearms, and hands||Weakness, atrophy, and loss of sensation in the lower legs, feet, forearms, and hands
Restless Legs Syndrome in some cases
|General muscle weakness, scoliosis, loss of (or reduced) sensation
Mild hearing loss in some cases
|Weakness, atrophy, and loss of sensation in the lower legs, feet, forearms, and hands; loss of ability to walk in some cases
Restless Legs Syndrome in some cases
|Muscle weakness both at the center of the body, and the extremities
Low muscle tone (in cases that start in infancy)
Cataracts, deafness, reduced touch sensitivity, and reduced ability to perceive temperature
What are the signs and symptoms of Charcot-Marie-Tooth Disease?
As alluded to in the table above, people who suffer from Charcot-Marie-Tooth Disease typically experience problems with their feet, muscle wasting, and weakness in their extremities. More specifically, CMT patients experience/exhibit:
- Breathing difficulties (rare)
- Burning sensation in hands and feet
- Clumsiness and loss of balance
- Cramping in legs and arms
- Decreased sensitivity to touch and temperature
- High arches (pes cavus)
- Flat feet (pes planus)
- Foot drop (inability to lift the foot at the ankle)
- Gait issues
- Loss of vision and/or hearing (rare)
- Numbness & loss of sensitivity in hands and feet
- Reduced fine motor skills
- Weak ankles
- Weakness in the arms and hands
How is CHARCOT-MARIE-TOOTH DISEASE Diagnosed?
There is an initial three-part diagnosis protocol for CMT. Doctors assess the patient’s medical history (partially to rule out other conditions), evaluate their family history (to determine if anyone else in their family is affected by the condition), and conduct a neurological exam (to see if symptoms typical of the conditions are present). Doctors also look for signs or characteristic anomalies, including hammertoes, high foot arches, muscle atrophy, mild scoliosis, or hip dysplasia.
If CMT is strongly suspected of being present, a neurologist will conduct the following tests to help confirm diagnosis:
- Nerve conduction test to measure the strength and speed of the electrical signals transmitted by the nerves
- EMG (electromyography) to measure the electrical signals received by the muscles in the arms and legs
- Nerve biopsy: a sample of a nerve is removed (usually from the patient’s calf), and analyzed for the appearance of CMT
- MRI to assess nerve size and fat to muscle ratio in affected areas
- Genetic test: a blood sample is analyzed to see if there are gene defects present that are associated with CMT
What is the treatment protocol for CHARCOT-MARIE-TOOTH DISEASE?
Although it is not a fatal condition, CMT can have a significant adverse impact on a patient’s ability to live independently and carry out basic activities of daily living such as getting dressed, walking, driving, or working. It can also have an impact on a patient’s emotional health. Most doctors recommend a combination strategy of treatment including:
- Occupational Therapy
- Fall-prevention strategies
- Fatigue-management strategies
- Workplace modifications
- Physical Therapy
- Exercise, such as swimming and biking
- Low-impact aerobics
- Stretching of the heel cord to reduce Achilles tendon tightening
- Strength training (moderate)
- TENS (transcutaneous electrical nerve stimulator)
- Talk Therapy
- Cognitive Behavioral Therapy (CBT)
- Orthoses and Assistive Devices
- AFOs (Ankle-foot orthoses)
- Ankle braces
- Custom-made shoes
- High-top shoes
- Orthotic inserts
- Thumb splints
- Zipper pullers
- Pain Management
- Anti-convulsants and TCAs for nerve pain
- Ibuprofen and NSAIDs for muscle and joint pain
- Orthopedic surgery to correct foot deformities, improve alignment, relieve pain, and increase strength
In addition to the interventions above, CMT sufferers should
- avoid alcohol and caffeine
- maintain a healthy weight and eat a healthy diet
- avoid exhaustion
- monitor their feet for injuries and/or sores.
Some patients have found complementary modalities such as acupuncture and meditation to be helpful.
Charcot-Marie-Tooth Disease progresses slowly in most cases, so most patients are able to lead full, active lives.
Lisa Hurley is a writer, Reiki practitioner, and certified sun-seeker. She is originally from Barbados, and now lives in Jersey City, New Jersey with her Jack Russell terrier King. She also happens to have an invisible illness (uveitis), and a chronic pain condition. She is passionate about helping other chronic pain warriors find the information they need to navigate their struggles, and feel stronger, more supported, and less alone. Lisa’s educational background includes a Bachelor’s in French, Spanish & Linguistics from the University of the West Indies, a Master’s in Music Business from New York University, and a Mini-MBA™ in Social Media from Rutgers University.
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