Peripheral neuropathy in Parkinson's disease.

BACKGROUND Recent studies suggest an increased frequency of peripheral neuropathy (PN) in Parkinson's disease patients (PD) (Toth et al. 2010). The aim of our study is to verify the increased frequency of PN in our group of PD patients compared to an age-matched control group. We sorted patients according to the duration of L-DOPA treatment, L-DOPA dosage, and age below or over 50 years. METHODS AND RESULTS We conducted electromyography examinations (using conduction studies and needle electromyography) of 49 PD patients with asymptomatic polyneuropathy and 40 controls. Patients without risk factors for PN were included (fasting blood was analyzed to rule out possible causes of PN), as were relatively healthy controls without risk factors for PN. PN was defined using the American Academy of Neurology and Electrodiagnostic Medicine criteria (England et al. 2005). CONCLUSION The frequency of polyneuropathy was significantly higher in PD patients than in controls (45% versus 2%, p<0.0001). We did not establish a relationship in the PD group according to long-term L-DOPA usage, PD duration, or age. It should be assumed that a neurodegenerative process underlies the involvement of the central and peripheral nervous systems in PD patients.