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Diseases of the Peripheral Nerve

The peripheral nervous system is composed of all of the nerves not located in the central nervous system; these are nerves in the face, arms, legs, torso and some cranial nerves. Nerves have the extremely important role of providing communication between the brain and muscles, skin, internal organs and blood vessels. If they are damaged, this communication is blocked. Consequently, this miscommunication causes symptoms such as pain or numbness.

Charcot-Marie-Tooth Disease (CMT) is now included in a group of disorders known as Hereditary Motor and Sensory Neuropathy (HMSN) or Peroneal Muscular Atrophy (PMA).

Charcot-Marie-Tooth Disease (CMT) is a neurological disorder that causes damages to the peripheral nerves. CMT is caused by defects in the genes for proteins found in axons, fibers that carry electrical signals between the brain and spinal cord and the rest of the body. Defects in genes for proteins found in myelin, a coating on axons that insulates and nourishes them, can also cause CMT. Usually diagnosed anywhere from birth to adulthood, common symptoms include muscle weakness and wasting as well as some loss of sensation in the feet, lower legs, hands and forearms. CMT patients often have contractures (stiffened joints) and sometimes develop scoliosis. The disease usually progresses slowly and is inheritable through a faulty gene contributed by each parent (autosomal dominant). CMT can also be X-linked, meaning it is inheritable through a gene on the X chromosome contributed by either parent.

Dejerine-Sottas Disease (DS) (also known as CMT Type 3 or Progressive Hypertrophic Interstitial Neuropathy)

Dejerine-Sottas disease is an inherited neurological disorder that progressively affects mobility. Peripheral nerves become enlarged or thickened leading to muscle weakness. Progress of the disorder is irregular and often accompanied by pain, weakness, numbness, and a tingling, prickling or burning sensation in the legs. Many people with Dejerine-Sottas disease continue to lead active lives. Most neurologists now consider this disorder to be one of 5 types of hereditary motor sensory neuropathy (HMSN) which simply means genetically transmitted disorder of the nerves associated with movement. Dejerine-Sottas disease is one of several that comprise Type III and in which the protective sheath around the long nerves breaks down (demyelination) for unknown reasons exposing and endangering the nerve. The nerves are enlarged due to an accumulation of connective tissue that may present in the form of "onion-bulbs".

Friedreich's Ataxia (FA) is a neurological disorder caused by defects in the gene that carries instructions for frataxin, a protein found in cellular structures called mitochondria. This results in diminished energy production in cells, including those of the nervous system and heart. Inheritance is brought on through a faulty gene contributed by each parent. Symptoms include ataxia (loss of balance and coordination), difficulty with speech and swallowing, muscle spasms, loss of sensation, skeletal and cardiac abnormalities, and possible diabetes or glucose intolerance. Typically FA is diagnosed between 10 and 15 years old.