Imaging the pre- and postsynaptic side of striatal dopaminergic synapses in idiopathic cervical dystonia: A SPECT STUDY Using [123I] epidepride and [123I] β-CIT

There is increasing evidence that a dysfunction of the dopaminergic system may be involved in the pathogenesis of idiopathic dystonia. To visualize possible alterations of the pre‐ and postsynaptic side of striatal dopaminergic synapses, SPECT studies using the radiotracers [123I] epidepride and [123I] β‐CIT were performed in 10 patients with idiopathic cervical dystonia. Eleven age‐ and sex‐matched subjects served as controls. [123I] Epidepride is a new highly affine marker of D2 receptors, and [123I] β‐CIT binds to dopamine transporters on dopaminergic nerve endings. [123I] Epidepride binding was significantly reduced in both striata of dystonia patients compared with controls (p < 0.05). In contrast, striatal [123I] β‐CIT uptake did not differ from controls. We conclude that dopaminergic dysfunction in idiopathic focal dystonia mainly involves postsynaptic mechanisms and suggest a disturbance of the indirect pathway of the motor circuit resulting in a disinhibited thalamocortical stimulation.