Infusion-rate-dependent Acute Neuropathic Pain with Duopa in a Patient with Parkinson's Disease and Pre-existing Neuropathy

Abstract

Objective: To report a case of rate dependent acute neuropathic pain with Carbidopa-lavadopa in a Parkinson's patient with preexisting neuropathy. Background: Subacute to chronic neuropathy has been associated with Parkinson's disease and levodopa therapy (including Carbidopa-lavadopa) 1-2. Infusion rate dependent acute neuropathic pain with Carbidopa-lavadopa are uncommon. Methods: Case Report Results: 68 year old gentleman with 20 year history of idiopathic Parkinson's disease with bilateral STN DBS (L- 2+1-, 2.0, 60, 130, R - 11-C+, 1.0, 60, 130) was evaluated for Carbidopa-lavadopa due to worsening dyskinesia and 4-6 hour off periods. His medications included amantadine 100mg three times a day and carbidopa-levadopa 4-6 tablets crushed and infused three times a day over 4 hours through a G-tube. He had history of idiopathic sensorimotor axonal polyneuropathy which was managed with 300mg once daily gabapentin. At the initial visit Carbidopa-lavadopa pump settings were: Lock level I, Continuous infusion rate 3.0 cc/h, Lock out 2 hours, Extra dose 1.5 cc and Morning dose 9 cc. Patient was discharged home at this setting when within 24 hours he developed severe neuropathic pain characterized by burning and stinging in his feet. He had no symptoms after he had morning bolus but by 2PM these symptoms started acutely. Continuous rate was reduced to 2.5cc/h which did not relieve the symptoms. Gabapentin dose was increased to 600mg two times a day when he developed severe dizziness. Duloxetine made him irritable. Continuous infusion rate was brought down to 1.4cc/h (with series of titrations) at which time the neuropathic pain was much improved. He has been using extra dose boluses to manage acute off periods. The boluses have not resulted in acute neuropathic pain. Conclusions: Acute worsening of neuropathic pain with infusion rate or duration might limit Carbidopa-lavadopa clinical benefit and adds to the expanding spectrum of neurotoxic side effects associated with this therapy.