DUODENAL L-DOPA CAN CAUSE POLYNEUROPATHY

Journal of Neurology [2012] Jan 24 [Epub ahead of print] (Santos-García D, de la Fuente-Fernández R, Valldeoriola F, Palasí A, Carrillo F, Grande M, Mir P, De Fabregues O, Casanova J.) Complete abstract 

Neurology [2011] 77 (22) : 1947-1950 (Y.A.Rajabally, J.Martey) Complete abstract

Reports have emerged describing the occurrence of polyneuropathy related to vitamin B12 deficiency and Guillain-Barré syndrome in people with Parkinson's Disease who are being treated with continuous duodenal L-dopa infusion. Duodenal L-dopa is administered as a gel throughout the day using a portable pump directly into the small intestine through a surgically placed tube. This ensures a flow of L-dopa that can be adjusted according to the patient's individual needs. For  more information on polyneuropathy go to Polyneuropathies.

At least 12 cases of polyneuropathy related to vitamin B12 deficiency, and a case of Guillain-Barré syndrome have been reported in people with Parkinson's Disease treated with duodenal L-dopa infusion. L-dopa gel infusion may cause a decrease in vitamin B12 levels, leading to peripheral neuropathy. Other detrimental effects include alterations related to the metabolism of L-dopa, abnormal L-dopa absorption, and direct neurotoxicity of L-dopa at high doses. Vitamin B12 supplements may need to be considered in people with Parkinson's Disease on duodenal L-dopa infusion therapy, because vitamin B12 deficiency in people on duodenal L-dopa infusion therapy may be more frequent than the published data suggest.