Charcot-Marie-Tooth disease (CMT) and muscular dystrophy (MD) may seem similar at first glance, both are inherited conditions that affect the muscles and nerves—but they have some important differences. Let’s explore what sets them apart and how they impact individuals differently.
What is CMT?
Charcot-Marie-Tooth disease (CMT) is named after the three doctors who first described the disease in 1886: Jean-Martin Charcot (shar-coh), Pierre Marie, and Howard Henry Tooth. Today, CMT refers to any peripheral neuropathy with a genetic cause, whether or not the specific genetic mutation is known.
CMT is a rare multisystem, multiorgan disease that causes lifelong, progressive symptoms, including muscle weakness and atrophy in the arms and legs, sensory loss, and other complications. These symptoms often lead to challenges with balance, walking, hand use, and other daily activities.
What is Muscular Dystrophy?
Muscular dystrophy (MD) refers to a group of genetic muscle diseases that cause progressive weakness and degeneration of the muscles responsible for movement. Unlike CMT, which affects the nerves that control muscle movement, MD affects the muscles directly.
While both MD and CMT can cause muscle weakness, they have different underlying causes and progress at different rates.
Key Differences Between CMT and MD
While both CMT and MD affect muscles and mobility, their underlying causes and progression are different.
- Cause of Muscle Weakness
- CMT: Caused by nerve damage, leading to muscle weakness and atrophy over time.
- MD: Caused by genetic mutations in the muscles themselves, leading to progressive muscle degeneration.
- Age of Onset
- CMT: Can appear at any age, often in childhood or adolescence, and progresses slowly over time.
- MD: Typically begins earlier, often in childhood, and tends to progress more rapidly.
- Muscle Groups Affected
- CMT: Primarily affects the feet, legs, and hands. Because CMT is a disease of the peripheral nerves, both muscle function and sensation are impacted. Sensory loss can contribute to balance issues and difficulty sensing limb position (proprioception).
- MD: Primarily affects skeletal muscles and does not affect the nerves.
- Progression of Symptoms
- CMT: Slowly progressive. Severity varies—some individuals experience mild symptoms, while others develop significant weakness, balance difficulties, severe muscle degeneration, and mobility loss. In some cases, CMT can also affect breathing muscles, but it does not cause primary cardiac muscle disease.
- MD: Typically progresses faster and often leads to widespread muscle degeneration, including direct involvement of heart muscle (cardiomyopathy).
Why CMT is Not a Form of Muscular Dystrophy
Despite some similarities in muscle weakness, CMT and muscular dystrophy are entirely different conditions. CMT is a disease of the peripheral nerves, while MD is a disease of the muscles themselves.
- CMT is a peripheral neuropathy, meaning the problem starts with the nerves that control muscles, leading to muscle weakness and atrophy over time.
- MD is a primary muscle disease where the muscles degenerate due to disease processes in the muscles, often progressing more rapidly.
This distinction is key to ensuring individuals with CMT receive the most accurate diagnosis, care, and support.
Final Thoughts: Understanding and Managing Both Conditions
Misconceptions about CMT and MD are common, but understanding their fundamental differences is essential for accurate diagnosis and care. CMT is a disease of the peripheral nerves, not the muscles, and recognizing this distinction ensures individuals with CMT receive the right medical care and support.
Want to learn more? Take a deeper dive on our What is CMT page.
Accurate diagnosis and expert care are key to managing CMT. Each CMTA Center of Excellence provides comprehensive specialty care and can help navigate the genetic testing landscape.
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