Thiethylperazine-induced parkinsonism:: in vivo demonstration of dopamine D2 receptors blockade

Thiethylperazine (Torecan((R))) is a piperazine phenothiazine employed to relieve vertigo. Its use may be associated with extrapyramidal side effects (dystonia, akathisia, tardive dyskinesia) (Sulkava, 1984), but parkinsonism has rarely been described. We describe a woman who, 1 month after the onset of thiethylperazine treatment, developed parkinsonism that disappeared 2 months after withdrawal of the drug. However, cerebral single-photon emission computed tomography (SPECT) with the dopamine (DA) D-2 receptors ligand I-123-iodobenzamide (I-123-IBZM) revealed a persistent reduced DA D-2 receptors activity (by 45%) in the basal ganglia (BG), which may be clinically not effective.