Therapeutic Effects of Dual Dopaminergic Modulation With l-DOPA and Chlorpromazine in Patients With Idiopathic Cervical Dystonia.

Objectives: Imbalanced activities between dopamine D₁ and D₂ signals in striatal striosome-matrix system have been proposed as a cause of dystonia symptoms. The aim of this study was to assess the therapeutic effects of dual dopaminergic modulation (DDM) with l-DOPA and chlorpromazine (CPZ) in patients with idiopathic cervical dystonia (CD).

Methods: We enrolled 21 patients with CD who responded poorly to botulinum toxin treatment. The severities of CD motor symptoms and CD-associated pain were determined using the Toronto Western Spasmodic Torticollis Rating Scale and the visual analog scale, respectively.

Results: In patients with CD (n = 7), oral administration of l-DOPA combined with CPZ significantly attenuated both CD motor symptoms and CD-associated pain in a dose-related manner. By contrast, there was no improvement of CD symptoms in patients (n = 7) who ingested l-DOPA alone nor in those (n = 7) who ingested CPZ alone.

Discussion: DDM with l-DOPA and CPZ may be an effective tool to treat dystonia symptoms in patients with botulinum toxin-resistant idiopathic CD. Our results may also indicate that CD dystonia symptoms could be attenuated through DDM inducing an increase in striosomal D₁-signaling.

Classification of evidence: This study provides Class III evidence that treatment of botulinum toxin-resistant idiopathic cervical dystonia with l-DOPA and chlorpromazine is superior to either one alone.