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Peripheral neuropathy is common in Parkinson's disease, and is associated with greater levodopa intake, according to a new study. Peripheral neuropathy (PN) was assessed in 58 randomly selected PD patients and 58 age- and sex-matched controls. PN was present in 55% of PD patients and 9% of controls (p<0.05). PN was symptomatic in 24 patients (41% of the entire sample). Comparing PD patients with PN to PD patients without PN, those with PN had similar duration of disease and time since diagnosis; greater disease severity; similar cobalamin levels; higher fasting homocysteine and methylmalonic acid; higher likelihood of using levodopa; and higher cumulative exposure to levodopa. Severity of peripheral neuropathy was associated with greater levodopa intake and higher methylmalonic acid levels. Elevated methylmalonic acid may lead to peripheral neuropathy, the authors note. MMA elevation can arise from cobalamin deficiency and from levodopa use. While they note they have not established a causal connection, they "suggest that L-dopa-induced elevations in MMA are responsible for the presence and severity of PN in IPD patients. We recommend screening for MMA levels in all PD patients receiving L-dopa to potentially identify patients with PN or at risk for PN." They also suggest studies of cobalamin supplementation for patients taking levodopa. Levodopa, methylmalonic acid, and neuropathy in idiopathic Parkinson disease C Toth, K Breithaupt, S Ge, Y Duan, JM Terris, A Theissen, S Wiebe, DW Zochodne, O Suchowersky Ann Neurol 2010;67:28-36 ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn