Objective: To describe a case series of valproate (VPA)-induced parkinsonism and increase awareness for this condition.

Background: VPA as a cause of parkinsonism has been rarely described. The association was first mentioned in 1994. In a 17 years’ review of drug-induced parkinsonism in a french pharmacovigilance center, only ten cases were due to VPA. Most reported patients were on VPA for treatment of epilepsy.

Methods: Retrospective review of VPA-induced parkinsonism cases observed from February 2012 to July 2015, in the Neurology department of a secondary care hospital (inpatient and outpatient consultations).

Results: We present 8 patients (6 male), aged 72 ± 6 years, treated with VPA for vascular epilepsy (n=6) or psychiatric disorder (n=2) with an average daily dose of 1379 ± 529 mg, who developed parkinsonism (Hoehn & Yahr: 3 ±1) after some days to ten years of drug exposure (median: 4 months). The parkinsonism was severe enough to require institutionalization or hospital admission in three cases. Postural tremor was often prominent. The symptoms reversed at least partially 8 ± 10 months after withdrawal (Hoehn & Yahr: 1.6 ±1).

Conclusions: VPA-induced parkinsonism may be either acute and severe soon after drug exposure or may develop insidiously in chronically treated patients. In this case, it might be indistinguishable from a neurodegenerative disorder. Our study suggests that elderly people might be more susceptible. As this is a reversible cause, all patients on VPA who develop parkinsonism should be offered a withdrawal trial to exclude an etiopathogenic role of this drug.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/valproate-induced-reversible-parkinsonism-a-case-series/