Efficacy and safety of valbenazine in the treatment of cervical dystonia: a pilot study

Background Vesicular monoamine transporter-2 inhibitors have provided on-label success in the treatment of tardive dyskinesia (TD) and Huntington’s disease chorea (HDC). A similar pathophysiological pathway for cervical dystonia suggests valbenazine (VBZ) could be beneficial in this condition. Objective To determine the efficacy of VBZ in reducing symptoms of pain and posturing and improving quality of life in subjects with cervical dystonia. Methods This was an open-label, prospective study of subjects with a clinical diagnosis of cervical dystonia currently being treated with botulinum neurotoxin (BoNT) for >6 months. Valbenazine was titrated to 80 mg per day with no change in BoNT dosage or muscle location. Evaluations were performed 4 weeks prior to the subject’s scheduled BoNT treatment date BoNTmax/-VBZ (time 1) compared to 4 weeks prior to the subject’s next BoNT treatment date BoNTmax/+VBZ (time 4). TheBoNT injection treatment date BoNTmin/VBZ dispensing (time 2) and the next BoNT injection treatment date BoNTmin/+VBZ (time 5) were compared. 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), Clinical Global Impression of Change (CGIC) and Patient Global Impression of Change (PGIC) Scales. Results Fourteen subjects were enrolled and followed for a total of 16 weeks. TWSTRS Total Score was significantly improved at time 4 compared to time 1 (p = 0.02), as well as VAS 0–10 scores for 24 Hour (p = 0.001), Past Week Pull (p = 0.0001), and Past Week Jerk (p = 0.04). TWSTRS Total Score was significantly improved at time 5 compared to time 2 (p = 0.02) as well as 24 Hour Pull (p = 0.01), 24 Hour Jerk (p = 0.04), Past Week Pull (p = 0.002), and Past Week Jerk (p = 0.02). Subjective improvement was reported at times 3, 4 and 5 on CGIC and PGIC Scales. No significant improvements were seen in the PSQI and NPDI. The medication was tolerated well with fatigue as the most common adverse effect. Conclusion This exploratory study demonstrates a potential benefit in the addition of VBZ for the treatment of cervical dystonia associated with severe pain and posturing.