title: Neuropathy as a potential complication of levodopa use in Parkinson's disease.
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 (PD-IPN) was compared to a group of PD patients without PN (PD-only), 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. PD-IPN 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 PD-IPN, and 32/34 (94%) had abnormal Hcy or MMA levels as compared to 26/258 (10%) of IPN patients. Cumulative lifetime L-dopa 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 PD-IPN 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.
authors.affiliation: Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada. corytoth@shaw.ca
authors.forename: Cory
authors.initials: C
authors.lastname: Toth
authors.forename: Martin Sutton
authors.initials: MS
authors.lastname: Brown
authors.forename: Sarah
authors.initials: S
authors.lastname: Furtado
authors.forename: Oksana
authors.initials: O
authors.lastname: Suchowersky
authors.forename: Douglas
authors.initials: D
authors.lastname: Zochodne
mesh_terms: D000704:Analysis of Variance; D000978:Antiparkinson Agents / Q000009:adverse effects*; D005260:Female; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007980:Levodopa / Q000009:adverse effects*; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood; D010300:Parkinson Disease / Q000150:complications / Q000188:drug therapy; D010523:Peripheral Nervous System Diseases / Q000209:etiology*; D012189:Retrospective Studies; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D000978:Antiparkinson Agents; D006710:Homocysteine; D007980:Levodopa; D008764:Methylmalonic Acid; D014805:Vitamin B 12