Multiple myeloma is a type of cancer that originates in the bone marrow and produces an abnormal protein that causes neuropathy. Researchers aren't sure why, but there's a particular type of monoclonal protein that causes neuropathy. The abnormal production and deposition of the protein complex amyloid leads to a disorder called amyloidosis, which in turn leads to peripheral neuropathy among other problems. It is usually a severe and painfully progressive disease. There are many substances known as neurotoxins that can cause severe damage to the peripheral nerves.
Neurotoxins can be drugs, heavy metals, or chemicals.
The heavy metals lead, mercury, arsenic and gold are all neurotoxins. Many industrial chemicals, including organophosphates and acrylamide, are neurotoxins. The most common cause of neuropathy worldwide is leprosy, a contagious disease caused by a bacterial infection. Patients usually have significant sensory loss and suffer injuires and other infections without realizing it. Treatment involves a potent schedule of antibiotics.