Atrophy, peroneal muscular

Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease (CMT) is one of the most common inherited neurological disorders, affecting approximately 1 in 2,500 people in the United States. The disease is named for the three physicians who first identified it in 1886 — Jean-Martin Charcot and Pierre Marie in Paris, France, and Howard Henry Tooth in Cambridge, England. CMT, also known as hereditary motor and sensory neuropathy (HMSN) or peroneal muscular atrophy, comprises a group of disorders that affect peripheral nerves. The peripheral nerves lie outside the brain and spinal cord and supply the muscles and sensory organs in the limbs. Disorders that affect the peripheral nerves are called peripheral neuropathies.

Charcot-Marie-Tooth disease (CMT) facts medically edited on Oct. 28, 2015, by Charles Patrick Davis, MD, PhD

• Charcot-Marie-Tooth disease (CMT) is composed of types of inherited neurological disorders that affect motor and sensory peripheral nerves (neuropathy), resulting in weakness in the musculature; the disease may get progressively worse over time. It is one of the most common (1 in 2,500 people) inherited neurological disorders. CMT is also known as HMSM (hereditary motor and sensory neuropathy) and peroneal muscular atrophy.
• Symptoms of Charcot-Marie-Tooth disease often begin in adolescence or early adulthood (some may occur early in life) and may include difficulty with
  • walking,
  • swallowing,
  • breathing, and
  • loss of muscle bulk, especially in the lower legs.
• The cause of Charcot-Marie-Tooth disease is inherited mutations in genes (also termed a hereditary motor and sensory neuropathy) that produce proteins that are involved in the structure of peripheral nervous system, specifically, axons or their myelin sheaths (myelin insulates and protects nerve cells); infrequently, Charcot-Marie-Tooth disease can occur with spontaneous mutation of the person’s gene.
• There are many forms of CMT (for example, CMT 1-4, CMTX, or type 1 or type 2); these forms or types are related to the mutations in the genes that alter the peripheral nerves and/or their myelin sheaths.
• Charcot-Marie-Tooth disease is diagnosed with the patient’s medical history, family history, and neurological examination. The physical examination may reveal
  • muscle weakness,
  • decreased muscle bulk,
  • leg pain,
  • foot drop (inability to control position of the foot), and
  • foot deformities such as hammertoes, high arches in the feet, or inverted heels.
  • Other tests such as nerve conduction studies, nerve, biopsy electromyography, and/or genetic testing also are available.
• Charcot-Marie-Tooth disease has no cure, but individuals may be helped (treated) with exercise, stretching, plus physical and occupational therapy. Many patients may benefit from use of orthopedic items, such as ankle braces and other items (thumb splints to help hand weakness), to give support so the patient maintains mobility.
• The majority of patients have a normal life span, but a few do not and experience severe progressive disease.
• Diagnosis is done by the patient’s family history, their physical exam, and symptoms; other tests may include nerve conduction studies, electromyography, or nerve biopsy to help distinguish CMT from other diseases like muscular dystrophies.
• The prognosis (outcome) varies with the disease severity and usually ranges from fair to poor, as the disease is progressive.
• Research is ongoing for Charcot-Marie-Tooth disease and includes gene therapy experiments, the use of nerve growth factors, vitamin C, and the use of curcumin (a component of curry) in animal models of this disease.
• A list of government and private organizations that can provide more detailed information about Charcot-Marie-Tooth disease and research on Charcot-Marie-Tooth disease is provided in this article.

The neuropathy of CMT affects both motor and sensory nerves. (Motor nerves cause muscles to contract and control voluntary muscle activity such as speaking, walking, breathing, and swallowing.) A typical feature includes

• weakness of the foot and lower leg muscles, which may result in foot drop and a high-stepped gait with frequent tripping or falls.
• Foot deformities, such as high arches and hammertoes (a condition in which the middle joint of a toe bends upwards) are also characteristic due to weakness of the small muscles in the feet.
• In addition, the lower legs may take on an “inverted champagne bottle” appearance due to the loss of muscle bulk.
• Later in the disease, weakness and muscle atrophy may occur in the hands, resulting in difficulty with carrying out fine motor skills (the coordination of small movements usually in the fingers, hands, wrists, feet, and tongue).

Onset of symptoms is most often in adolescence or early adulthood, but some individuals develop symptoms in mid-adulthood. The severity of symptoms varies greatly among individuals and even among family members with the disease. Progression of symptoms is gradual. Pain can range from mild to severe, and some people may need to rely on foot or leg braces or other orthopedic devices to maintain mobility. Although in rare cases, individuals may have respiratory muscle weakness, CMT is not considered a fatal disease and people with most forms of CMT have a normal life expectancy.