To determine the efficacy of valbenazine (VBZ) in reducing pain/spasm and improving quality of life in subjects with cervical dystonia. 

Vesicular monoamine transporter-2 inhibitors have provided on-label success in the treatment of hyperkinetic disorders including Huntington's disease and tardive dyskinsisa. A similar pathophysiological pathway for cervical dystonia suggests VBZ could be beneficial in this condition.

This was an open-label, prospective study of subjects with a clinical diagnosis of cervical dystonia currently being treated with botulinum toxin (BTX) for >6 months. Valbenazine was titrated to 80 mg per day with no change in BTX dosage or muscle location. Evaluations were performed four weeks prior to the subject’s scheduled BTX treatment date/-VBZ (time 1) compared to four weeks prior to the subjects next BTX treatment date/+VBZ (time 4). A second comparison was made between the BTX injection treatment date/VBZ dispensing (time 2) and the next BTX injection treatment date/+VBZ (time 5). Efficacy was assessed using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTR), Neck Pain Disability Index (NPDI). visual analog scale (VAS, 0-10) for pain/pulling/jerking, Pittsburgh Sleep Quality Index (PSQI), Investigator Global Assessment of Efficacy (IGAE), and Patient Evaluation of Global Response (PEGR).

Thirteen subjects were enrolled and followed for a total of 16 weeks. TWSTRS scores were significantly improved at time 4 compared to time 1 (p=0.01), as well as VAS pulling (p=0.02). TWSTRS total, pain, and disability subset scores, NPDI, and VAS for pain/pulling/jerking were all significantly improved at time 5 compared to time 2 (p=0.01). No significant improvements were seen in the PSQI, IGAE, or PEGR. The medication was tolerated well with sedation as the most common adverse effect.

This exploratory study suggests a potential benefit of VBZ for the treatment of cervical dystonia when added to BTX treatment.