What Is Charcot-Marie-Tooth Disease? Singer Alan Jackson Says He Has It

Charcot-Marie-Tooth disease (CMT) is an inherited neurological disorder. The illness affects the peripheral nervous system and affects over 126,000 people in the United States and 2.6 million people worldwide, according to the National Institute of Neurological Disorders and Stroke (NINDS).

There are ways to manage the symptoms of CMT, but there isn't a cure. Typically, the disease does not impact a person's life expectancy. However, it is common for CMT sufferers to have some sort of physical or mobility disability.

Country singer Alan Jackson was diagnosed with Charcot-Marie-Tooth disease in 2011, according to TODAY. "I have this neuropathy and neurological disease," said Jackson. "It's genetic that I inherited from my daddy. There's no cure for it, but it's been affecting me for years.

"And it's getting more and more obvious. And I know I'm stumbling around on stage," explained Jackson. "And now I'm having a little trouble balancing, even in front of the microphone, and so I just feel very uncomfortable."

What Is Charcot-Marie-Tooth Disease?

Charcot-Marie-Tooth disease is a group of disorders named after the three researchers who first described it in 1866. The disease causes damage to the peripheral nerves. According to the NINDS, the job of peripheral nerves is to send signals and information from the brain and spinal cord to the rest of the body. The disease can start at any age, according to the NINDS, but people with the condition tend to develop progressive muscle weakness in their adolescence or early adulthood.

"CMT is a genetic disease, which means it will get worse over time," noted Amit Sachdev, MD, medical director in the department of neurology at Michigan State University.

What Are the Symptoms?

Because CMT affects the peripheral nerves, which include sensory and motor nerves that trigger an impulse for muscle contractions, it can lead to various symptoms. "CMT will cause both issues of sensation and strength," noted Dr. Sachdev.

NINDS-reported symptoms include:

• Muscle weakness in your legs, ankles, and feet
• Muscle cramps
• Nerve pain
• Tremor
• Loss of muscle bulk (atrophy) in your arms, legs, hands, and feet
• Difficulty lifting your foot (foot drop)
• Frequent tripping or falling
• Balance issues
• Foot deformities (high foot arches and curled toes)
• Reduced ability to feel heat, cold, or touch
• Scoliosis (curvature of the spine)
• Hip displacement
• Problems with hearing and vision
• Breathing difficulties

There is a "broad range of severity" with CMT, added Paul Twydell, DO, a neurologist at Spectrum Health. "Some people develop it in childhood or adolescence. They typically have more weakness and need orthotics and equipment to help them walk, Other people don't get diagnosed until later in life—they tend to have a milder form of it."

What Causes CMT?

NINDS says that CMT is the result of genetic mutations that may damage the nerves or the myelin sheath—the protective coating surrounding the nerve. Such damage can cause weaker messages to travel between the limbs and the brain.

There are three different patterns of this gene mutation: autosomal dominant, autosomal recessive, and x-linked. The chances of inheriting CMT vary depending on what kind of gene mutation you have.

The autosomal dominant mutation means that only one parent with the CMT gene is needed to get the disease. So with that mutation, a child of an affected parent has a 50% chance of developing CMT.

The autosomal recessive mutation means that a person receives two mutated genes—one from each parent (the parents normally do not have CMT, just the gene for it.) A child of the affected parents would have a 25% chance of inheriting the disease.

The X-linked mutation is when the mother has the mutation on one of their X chromosomes, according to the NINDS. The chances of inheriting the disease with an x-linked mutation vary depending on the sex of the child.

Diagnosing

There are quite a few ways that a healthcare provider can diagnose CMT. NINDS tells us that a diagnosis can involve several tests, including some of the following techniques.

Nerve Conduction Studies

During nerve conduction studies, electrodes are placed on the skin over a muscle or a nerve. Those electrodes will create a small electrical impulse that stimulates the nerves. Information is then collected from this electrical activity.

Electromyography (EMG)

Electromyography (EMG) involves the insertion of a needle electrode through the skin to the muscle. THAT measures the bioelectrical activity of the muscles.

Physical Exam

A healthcare provider will perform a physical exam to look for any evidence of muscle weakness, atrophy, reduced tendon reflexes, sensory loss, or any other physical symptoms that may be present, said NINDS. One specific sign of CMT is nerve enlargement, called hypertrophic nerves. That can be felt or seen through the skin and is caused by a thickened myelin sheath on the nerve.

"The most common thing we look for when diagnosing CMT is a high arch," said Clifford Segil, DO, a neurologist at Providence Saint John's Health Center in California. CMT also tends to affect the nerves outside the foot, giving healthcare providers a good clue about what may be behind a patient's symptoms. 

"It's fairly easy to diagnose," added Dr. Segil.

Genetic Testing

Given that CMT is an inherited condition, your healthcare provider will also likely ask questions about your family history, said Dr. Sachdev. Genetic testing can also involve bloodwork.

Nerve Biopsy

Sometimes, healthcare providers may perform a nerve biopsy to confirm the diagnosis of CMT. Typically, a peripheral nerve sample will be taken from the calf and then analyzed under a microscope.

Treating CMT

There is no cure for CMT, but patients may be treated with medication to help with nerve pain, according to the NINDS. It's also important to maintain mobility, flexibility, and muscle strength. 

"A healthy body will carry the nerves a long way," noted Dr. Sachdev.

Ankle braces and other orthopedic devices can help people with CMT get around more easily, Dr. Twydell said. 

Some people with the condition may also have orthopedic surgery to treat severe foot pain and joint deformities, according to the NINDS.

A Quick Review

CMT is one of the most common inherited neurological disorders, said NINDS. The disease can affect your muscles and the way you walk and can even cause some deformities. Still, CMT doesn't typically affect someone's life expectancy.

 "It's not going to kill me. It's not deadly," said Jackson.  Even though there isn't a cure, there are treatment options available that can improve the symptoms.