Charcot-Marie-Tooth (CMT) disease is a hereditary neurological condition that affects the peripheral nerves—those responsible for movement and sensation in the limbs. It is one of the most common inherited neurological disorders. Charcot-Marie-Tooth causes progressive muscle weakness, foot deformities, balance difficulties, and sensory loss, particularly in the feet and lower legs. Most patients begin experiencing symptoms in childhood or early adulthood, and the condition typically progresses slowly over time. Although it is not life-threatening, CMT can significantly impact mobility and quality of life.
What is Charcot-Marie-Tooth Disease?
Causes and Risk Factors
Charcot-Marie-Tooth is a genetic disorder, meaning it is caused by inherited mutations in genes that affect the structure and function of peripheral nerves. These mutations may disrupt the nerve’s ability to transmit signals effectively, either by damaging the nerve fibers (axons) or the protective myelin sheath around them.
Key causes and risk factors include:
- Family History: The most significant risk factor is having a parent with CMT.
- Genetic Mutation: Mutations in over 100 genes have been linked to CMT, with CMT1A (caused by PMP22 gene duplication) being the most common subtype.
Unlike many foot and ankle disorders, CMT is not caused by injury or lifestyle and cannot be prevented. However, early diagnosis and management can help slow progression and reduce complications.
Symptoms
The symptoms of CMT typically begin in the feet and legs and may progress to the hands and arms over time. Common symptoms include:
- Foot Drop: A condition where the front part of the foot cannot be lifted properly, causing the toes to drag while walking. To compensate, patients often develop a high-stepping gait to avoid tripping.
- Muscle Weakness: Especially in the lower legs and feet, resulting in frequent tripping or difficulty with balance.
- Foot Deformities: High arches (pes cavus), hammertoes, and ankle instability are common due to muscle imbalances.
- Loss of Sensation: Numbness or reduced ability to feel pain and temperature in the feet and lower legs.
- Balance and Coordination Issues: Because of weakness and sensory loss, patients often struggle with uneven terrain .
Symptoms and severity can vary widely—even among family members with the same genetic form of CMT.
Diagnosis
Diagnosing Charcot-Marie-Tooth disease typically involves a combination of:
- Clinical Examination: A neurologic and musculoskeletal assessment to evaluate muscle strength, reflexes, and foot deformities.
- Family History: Understanding genetic background is important in identifying inherited neuropathies.
- Nerve and Muscle Testing: This includes two separate tests. Nerve conduction studies (NCS) measure how quickly and effectively electrical signals travel through your nerves. Electromyography (EMG) evaluates the electrical activity of muscles to assess for signs of nerve or muscle damage. Together, these tests help determine the type and severity of neuropathy.
- Genetic Testing: Can confirm the diagnosis by identifying specific gene mutations associated with CMT.
- Imaging: While not typically used to diagnose CMT, foot and ankle X-rays, CTs, or MRIs may be helpful when planning surgical treatment for deformities.
Early and accurate diagnosis is important for managing symptoms and preventing complications like ulcers or joint degeneration.
Treatment
There is currently no cure for CMT, but treatment focuses on maintaining mobility, preventing complications, and improving quality of life. A multidisciplinary approach often provides the best outcomes.
Conservative Treatments:
- Physical Therapy: Targeted exercises can help maintain strength, flexibility, and balance.
- Occupational Therapy: Helps improve fine motor function and daily activities.
- Bracing: Ankle-foot orthoses (AFOs) can help correct foot drop and provide stability.
- Custom Orthotics: Shoe inserts can support foot alignment and relieve pressure points.
- Pain Management: Neuropathic pain, if present, can be managed with medications like gabapentin or amitriptyline.
Surgical Treatments:
- Foot Reconstruction: Surgery may be recommended to correct high arches, hammertoes, or other deformities that cause pain or impair function.
- Tendon Transfers: Can help rebalance muscles and improve foot position.
- Osteotomy: Bone-cutting procedures may be used to realign the foot or ankle.
- Joint Fusion: In severe deformities, fusing a joint can stabilize the foot and relieve pain.
Treatment is highly individualized based on the patient’s symptoms, functional limitations, and goals.
