There are many causes of peripheral neuropathy and in about 30% of cases; the cause is unknown and referred to as idiopathic neuropathy. Common causes include:
- Diabetes – The longer the duration of diabetes, the greater the chance of developing neuropathy. It is estimated that half of all people who have been living with diabetes for 25 years or more have diabetic neuropathy.
- Vitamin deficiencies – especially vitamin B12, but also other B vitamins such as B1, B6, B3, and vitamin E
- Alcoholism – due to nutritional deficiencies and many think as a direct effect of the alcohol
- Trauma – physical injury to a nerve; may be seen with repetitive stress and with any condition that traps, compresses, or damages a nerve (e.g., carpal tunnel syndrome).
Other causes include:
- Kidney, liver and lung disease, or other chronic illness
- Hypothyroidism and pituitary disorders
- Autoimmune disorders such as Guillain-Barré syndrome, rheumatoid arthritis, and systemic lupus erythematosus (SLE).
- Some cancers, either through production of substances that damage peripheral nerves (paraneoplastic syndrome) e.g. lymphoma, multiple myeloma or lung cancer, or through direct compression of the nerve itself.
- A wide range of infections, including: shingles (varicella zoster virus), Lyme disease, HIV/AIDS, cytomegalovirus (CMV), Epstein-Barr virus, syphilis, leprosy, diphtheria, and parasites
- Exposure to toxins, such as the heavy metals lead, arsenic, and mercury, or to other environmental toxins.
- Some medications can cause peripheral neuropathy as a side effect. These include: antiretrovirals (for treatment of HIV infections), microtubule inhibitors (a type of chemotherapy), metronidazole, thalidomide (used in treatment of multiple myeloma), phenytoin and disulfiram (for treatment of alcohol dependence).
- Other rare, inherited disorders such as Charcot-Marie-Tooth disease