The Charcot-Marie-Tooth disease (CMT) affects the peripheral nerves, which are the nerves outside of the brain and spinal cord. It is the most common form of inherited peripheral neuropathy, and affects one in 2,500 individuals worldwide. It causes muscle weakness, loss of sensation, foot deformities, and difficulty walking.
CMT is caused by genetic mutations that affect the structure or function of the peripheral nerves. Mutations can damage nerve fibers (axons) or protective coatings around them (myelin sheaths). CMT is inherited differently depending on the type of mutation and the gene involved:
Autosomal dominant: This means that only one copy of the mutated gene from either parent is enough to cause the disease. This is the most common inheritance pattern for CMT.
Autosomal recessive: This means that both copies of the mutated gene from both parents are needed to cause the disease. This is a less common inheritance pattern for CMT.
The most common inheritance pattern for CMT is autosomal dominant, which means that only one copy of the mutated gene is necessary to cause the disease. X chromosomes. Males who inherit the mutated gene from their mother will develop the disease, while females who inherit one copy of the mutated gene from either parent will be carriers and may or may not have symptoms.
The symptoms of CMT usually begin in childhood or early adulthood, but they can also appear later in life. The severity and progression of symptoms can vary greatly from person to person, even among family members. The most common symptoms of CMT include:
Muscle weakness in the legs, ankles, feet, hands, and arms
Muscle wasting or atrophy in the affected areas
High foot arches (pes cavus) or flat feet (pes planus)
Curled toes (hammer toes) or clawed fingers
Decreased or absent reflexes in the limbs
Decreased or lost sensation in the feet, legs, hands, and arms
Difficulty walking, running, or balancing
Frequent tripping or falling
Foot drop, which is the inability to lift the front part of the foot
Chronic pain, cramps, or fatigue in the muscles
Scoliosis, which is an abnormal curvature of the spine
Breathing problems, if the respiratory muscles are affected
Hearing loss or deafness, if the auditory nerve is affected
Vision problems, if the optic nerve is affected
The diagnosis of CMT is based on the following:
Medical history: The doctor will ask about the symptoms, family history, and any medications or other conditions that may affect the nerves.
Physical examination: The doctor will examine the muscles, reflexes, and sensation in the limbs, and look for any signs of foot deformities or scoliosis.
A nerve conduction study measures how well and how fast the nerves can send electrical signals. Patients with CMT usually have slower or weaker nerve signals than normal.
EMG: Electromyography measures the electrical activity of muscles. It involves inserting thin needles into the muscles and recording the signals they produce. People with CMT usually have abnormal or less muscle activity than normal.
It involves taking a blood sample and analyzing the DNA to identify the specific gene mutation that causes CMT. A genetic test can confirm a diagnosis, determine the type and inheritance pattern of CMT, and provide genetic counseling and information regarding family planning.
There is no cure for CMT, but treatments can help manage the symptoms and improve the quality of life. The treatment options for CMT include:
Some medications may relieve muscle pain, cramping, or fatigue, including nonsteroidal anti-inflammatory drugs (NSAIDs), anticonvulsants, antidepressants, or opioids. Some medications, however, can worsen nerve damage or cause side effects, so they should be taken with caution and under the doctor's supervision.
A physical therapist maintains or improves the strength, flexibility, and range of motion of the muscles and joints through exercises and stretches. Besides preventing or correcting foot deformities, physical therapy can also improve balance and coordination, and delay or prevent muscle atrophy.
Learning skills and techniques for performing daily activities more easily and independently is the goal of occupational therapy. To improve mobility and function, occupational therapy can also assist with the use of adaptive equipment or devices, such as braces, splints, orthotics, or wheelchairs.
A foot deformity or scoliosis caused by CMT may be corrected or repaired by orthopedic surgery. Surgery can alleviate pain, improve appearance, and prevent further complications. Surgery does, however, carry some risks and may not restore normal function or sensation.
A genetic counselor can help people with CMT and their families make informed decisions about family planning, testing, and treatment by discussing inheritance patterns, risk factors, and implications for CMT.
There is no way to prevent CMT, as it is a genetic condition that is present from birth. However, some measures can help prevent or reduce the complications and improve the prognosis of CMT. These include:
Avoiding or limiting the exposure to factors that can worsen the nerve damage, such as alcohol, smoking, toxins, infections, or certain medications
Following a healthy diet and lifestyle to maintain a normal weight and prevent diabetes, which can also affect the nerves
Seeking regular medical care and monitoring to detect and treat any problems early
Joining a support group or seeking psychological help to cope with the emotional and social challenges of living with CMT
