DUODENAL L-DOPA CAN CAUSE POLYNEUROPATHY

26th January 2012 - New research

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.)  

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

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.

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.

In another new study, over a third (37%) of people with Parkinson's Disease were found to have neuropathy. Vitamin B12 deficiency was the most common cause. This could be made more likely by the long term use of L-dopa in any form. Many people with Parkinson's Disease who have neuropathy or Vitamin B12 deficiency are unaware of it.