Abstract
The presence and potential etiologies of peripheral neuropathy (PN) in patients with Parkinson's Disease (PD) is unknown. We examined for presence of PN in patients with PD. From a PD patient population of 500 patients screened for features of symptomatic PN, patients were further selected for clinical, electrophysiological, and laboratory studies related to PN. This PD patient population with idiopathic PN (PDβIPN) was compared to a group of PD patients without PN (PDβonly), and a large group of patients without PD with idiopathic PN (IPN) for abnormalities in Cbl, fasting homocysteine (Hcy), and fasting methylmalonic acid (MMA) levels. PDβIPN and IPN patients identified with abnormalities in Cbl, Hcy, or MMA levels were treated with intramuscular Cbl for 1 to 2 years. Of 49 PD patients with symptomatic PN, 34 patients (69%) had PDβIPN, and 32/34 (94%) had abnormal Hcy or MMA levels as compared to 26/258 (10%) of IPN patients. Cumulative lifetime Lβdopa dosage and fasting MMA levels were associated with PN severity. Cbl therapy led to improvements in Hcy and MMA levels in all groups, and PN in PDβIPN patients stabilized during therapy. PN in PD patients may be associated with iatrogenic Cbl metabolic abnormalities. Alternatively PN may be a peripheral nervous system manifestation of PD. Β© 2008 Movement Disorder Society