Polyneuropathy while on duodenal levodopa infusion in Parkinson's disease patients: We must be alert

Some reports have emerged describing the occurrence of Guillain- Barré syndrome and polyneuropathy related to vitamin B 12 deficiency in some patients with Parkinson's disease (PD) treated with continuous duodenal levodopa infusion. We describe five PD patients who developed axonal polyneuropathy and vitamin B 12 deficiency while on treatment with duodenal levodopa infusion, review other cases reported in the literature, discuss potential etiologic factors, and suggest a possible algorithm for the management and prevention of this complication. One case of Guillain-Barré syndrome and at least 12 cases of polyneuropathy related to vitamin B 12 deficiency have been reported in PD patients treated with duodenal levodopa infusion. Levodopa gel infusion may induce a decrease in vitamin B 12 levels, leading to peripheral neuropathy. Additional pathogenetic mechanisms include alterations related to the metabolism of L-dopa, abnormal L-dopa absorption, and direct neurotoxicity of L-dopa at high doses. Vitamin B 12 supplementation may need to be considered in PD patients on duodenal levodopa infusion therapy. Vitamin B 12 deficiency in patients on duodenal levodopa infusion therapy may be more frequent than the published data suggest. We must be alert. © Springer-Verlag 2012.F. Carrillo and P. Mir were supported by grants from the Ministerio de Ciencia e Innovación de España (SAF2007-60700); the Instituto de Salud Carlos III (PI10/01674); the Consejería de Innovación, Ciencia y Empresa de la Junta de Andalucía (CVI-02526); the Consejería de Salud de la Junta de Andalucía (PI-0377/2007, PI-0741/2010), the Sociedad Andaluza de Neurología and the Jaques and Gloria Gossweiler Foundation. The remaining authors received no relevant financial support and funding for the preceding 12 months.Peer Reviewe