Parkinson disease and polyneuropathy

Abstract

In their article, “Neuropathy in Parkinson disease: Prevalence and determinants,” Rajabally and Martey1 take a closer look at a problem that has been discussed for several years.2,3 The problem is very specific. Some people with Parkinson disease (PD) develop something called a polyneuropathy. This is a problem of the nerves in the feet and hands. It starts gradually, and over a long period of time, gets worse. When it happens, it usually affects the feet first, and later, the hands. Both are affected equally. One concern is that the medication that is used most often for PD may be the cause of the nerve problem. This medication is called levodopa. In other words, the treatment of one illness may be the cause of a second illness. Because this association is unclear, the authors decided to look more closely at the relationship between levodopa and polyneuropathy. Between October 2010 and February 2011, Rajabally and Martey searched for 2 groups of patients. The first were people with PD. The second group included people who had other neurologic illnesses (like migraines or seizures). The reason they needed to select 2 groups was for comparison. There are many causes for polyneuropathy. The most common causes are diabetes and long-term alcohol use or abuse. In addition, vitamin deficiencies (especially vitamin B12) can cause a polyneuropathy. As the authors were searching for people to study, they excluded those who had diabetes, alcoholism, or a known vitamin (B12) deficiency. In this way, they were able to minimize other factors which might make the results more confusing. Rajabally and Martey identified 37 people with PD. They matched these people with 37 people who were the same age and gender. Both groups were studied in exactly the same way. The participants …