Reversible parkinsonism with normal β-CIT-SPECT in patients exposed to sodium valproate

After reports of reversible parkinsonism and cognitive impairment with sodium valproate (VPA), the authors examined 50 consecutive patients taking VPA and 20 patients taking carbamazepine. Three patients taking VPA exhibited unequivocal parkinsonism with Unified Parkinson Disease Rating Scale scores >30. VPA was withdrawn from two patients with improvement of symptoms. Reduction in VPA dosage in the third patient produced no improvement. β-CIT-SPECT scans were normal, suggesting dopaminergic neuronal loss is not the underlying mechanism.