035 Valproate-induced parkinsonism ‘an early warning’: case reports and review of literature

IntroductionWe describe two cases of valproate-induced parkinsonism, where the parkinsonian features develop after commencing valproate (VPA), in a time frame and manner well described by previous publications.1 In contrast to the published literature, that has short duration of follow-up, we have had a prolonged follow-up of these two cases, who initially improved on ceasing valproate, but then after a period progressed again, with the development of levodopa-responsive asymmetrical Parkinson’s disease.2Cases67 years old man, on VPA 500 mg twice a day for seizures since 2008, developed new rest, re-emergent left hand tremor and hypomimia in 2012. Within months, the parkinsonism progressed to decremental bradykinesia, cog-wheel rigidity and hypophonia. The symptoms initially improved with changing VPA to levetiracetam; however, the disease reappeared after 6 months and although levodopa-responsive, it has been progressive since then.88 years old man, on VPA 700 mg twice a day for seizures since 2010, developed upper limb decremental bradykinesia, cog-wheel rigidity, camptocormia and rest, re-emergent tremor in hands in 2011. The parkinsonism improved significantly with cessation of VPA; however, the disease re-emerged after 2 years and has been progressive since then.ConclusionVPA may be responsible for unmasking underlying subclinical parkinsonism and these patients represent an earlier onset of Parkinson’s disease related to VPA exposure, rather than a purely drug related parkinsonian dysfunction. These cases also highlight the importance of long-term follow up in VPA-induced parkinsonism. These observations are an important consideration for clinicians treating patients with parkinsonian features secondary to VPA exposure.ReferencesBrugger F, Bhatia KP, Besag FM. Valproate-associated parkinsonism: a critical review of the literature. CNS Drugs 2016;30(6):527–540.Mahmoud F, Tampi RR. Valproic acid-induced parkinsonism in the elderly: a comprehensive review of the literature. Am J Geriatr Pharmacother 2011;9(6):405–412.

Extrapyramidal manifestations complicating organophosphorus insecticide poisoning

Six patients who developed extrapyramidal manifesta tions following poisoning with the organophosphorus (OP) insecticide fenthion are reported. The extrapyramidal fea tures, in order of frequency, were dystonia, rest tremor, cog-wheel rigidity, and choreo-athetosis. The delay in onset of these signs, following poisoning, varied from 4 to 40 days, and they disappeared spontaneously in about 1 to 4 weeks in those who survived. The human extrapyrami dal system is rich in cholinergic neurons and acetyl cholinesterase (AChE). Inhibition of AChE by fenthion, which has ready access to central neurons on account of its lipid solubility, is postulated as the mechanism under lying the extrapyramidal manifestations.