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• Porphyria (a group of genetic disorders caused by problems with how the body makes a substance called heme, a component of hemoglobin)
• Diphtheria
• Vasculitis
• Tumor
• Certain medications

Chronic Polyneuropathy

Chronic polyneuropathy, sometimes called chronic distal neuropathy is the most common type of polyneuropathy and may develop over a period of months or years. It can involve large and/or small fibers and can affect sensory, motor, and/or autonomic pathways. There are several subtypes of chronic polyneuropathy including:

• Chronic Demyelinating Polyneuropathy - demyelination refers to the destruction and loss of myelin from the sheath surrounding the axon and affects both near and far segments of the nerve. It is characterized by progressive weakness and impaired sensory function in the legs and arms. It is more common in males than females and in young adults. This condition is either genetic or may be acquired (inflammatory or immunological conditions).

  • Genetic etiology reflects a duplication of the PMP22 gene which is highly associated with Charcot-Marie-Tooth (CMT) disease.
  • Acquired etiology is related to immunological conditions - most commonly to chronic inflammatory demyelinating polyneuropathy (CIDP) which is thought to affect 2 out of 100,000 people, or multifocal motor neuropathy.

• Chronic Axonal Polyneuropathy - This is the most common of the polyneuropathy conditions. It is more common than demyelinating polyneuropathy and is characterized by ascending nerve damage, meaning that the nerve fibers most distant from the brain and spinal cord are affected first. Pain or other symptoms may appear in both feet and gradually progress up the legs and then appear in the fingers, hands, and arms. It is associated with many conditions including:

  • diabetes (most common)
  • nutritional deficiencies (e.g. vitamin B12)
  • cancer
  • renal failure
  • medication toxicity
  • alcohol abuse

While acute neuropathies tend to appear suddenly, progress rapidly, be potentially life threatening, and resolve slowly, chronic neuropathies progress slowly and worsen over time but are typically not fatal. Some patients find that symptoms plateau at a given point while for other patients, symptoms relapse and remit.

In approximately 20-25% of cases, no cause can be found for chronic polyneuropathy and these patients are said to have idiopathic peripheral neuropathy. Most cases of idiopathic peripheral neuropathy involve sensory nerves. Symptoms are symmetrical and typically start distally, (usually in the feet) with pain, numbness, or burning. Idiopathic peripheral neuropathy affects primarily older patients. Progression of symptoms is slow and usually does not result in serious physical disability although quality of life can be significantly impacted due especially to pain and dysesthesia (distorted sensation where light touch is perceived as painful).

For more in-depth information regarding various types of peripheral neuropathy, please click on the following link: http://www.medifocus.com/abstracts.php?gid=NR021&ID=15220040

Underlying medical conditions that may cause specific types neuropathy include:

• Acute motor paralysis with minimal sensory disturbance

  • Guillan-Barre syndrome
  • diphteritic polyneuropathy (muscles of swallowing and speech are also involved)

• Mononeuropathy multiplex

  • diabetes mellitus
  • sarcoidosis
  • polyarteritis nodosa

• Subacute sensorimotor polyneuropathy

  • nutritional deficiencies - thiamine, niacin, or vitamin B12 deficiency
  • poisoning with heavy metals and solvents