Long-Term Safety and Efficacy of Repeat Treatments of DaxibotulinumtoxinA for Injection in Adults With Isolated Cervical Dystonia (ASPEN-OLS)

Inclusion Criteria: * Meets diagnostic criteria for isolated CD (idiopathic; dystonic symptoms localized to the head, neck, shoulder areas) with at least moderate severity at Baseline (Day 1), defined as a TWSTRS-total score of at least 20, with at least 15 on the TWSTRS-Severity subscale, at least 3 on the TWSTRS-Disability subscale, and at least 1 on the TWSTRS-Pain subscale (minimum TWSTRS subscale criteria applicable only to subjects not previously enrolled in Study Protocol 1720302) * Subjects who were previously enrolled in Study Protocol 1720302, and completed the study, including: * Those with no reduction or have an increase from baseline in the average TWSTRS-total score at Weeks 4 and 6 (i.e., no improvement or worsened disease status), and the investigator agreed that there was a need for retreatment based on the subject's symptoms and neurologic exam findings * Those who benefited from study treatment and completed follow-up study visits up to the time point of when their TWSTRS - total score reached/exceeded their target TWSTRS score * Those who benefited from study treatment but subsequently experienced significant recurrence of CD symptoms (e.g. pain) during the study before their TWSTRS-total score reached their target TWSTRS score and requested retreatment, which the investigator determined was warranted based on the subject's symptoms and neurologic exam findings * Those who completed study visits up to Week 36 and their TWSTRS-total score never reached their target TWSTRS score and they never requested another treatment. The investigator determined that these subjects can be followed in the OLS until their TWSTRS-total score is the same or higher than their target TWSTRS score or until they request retreatment, which the investigator determined is clinically indicated * De novo subjects (not previously enrolled in Study Protocol 1720302): * Naïve to BoNT treatment * BoNT treatment-experienced; if previously treated with BoNTA, the subject must have demonstrated a clinically meaningful response to the last BoNTA treatment based on the clinical judgment of the investigator Exclusion Criteria: * Cervical dystonia attributable to an underlying etiology, (e.g., traumatic torticollis or tardive torticollis) * Predominant retrocollis or anterocollis CD * Significant dystonia in other body areas, or is currently being treated with botulinum toxin (BoNT) for dystonia in areas other than those associated with isolated CD * Severe dysphagia (Grade 3 or 4 on the Dysphagia Severity Scale) at Screening or Baseline (prior to study treatment) * Any neuromuscular neurological conditions that may place the subject at increased risk of morbidity with exposure to BoNT, including peripheral motor neuropathic diseases (e.g., amyotrophic lateral sclerosis and motor neuropathy, and neuromuscular junctional disorders such as Lambert-Eaton syndrome and myasthenia gravis) * Previous treatment with any BoNT product for any condition within the 14 weeks prior to Screening (applicable only to de novo subjects) * Botulinum neurotoxin treatment-experienced subjects who had suboptimal or no treatment response to the most recent BoNTA injection for CD, as determined by the investigator; or history of primary or secondary non-response to BoNTA injections, known to have neutralizing antibodies to BoNTA; or have a history of botulinum toxin type B (rimabotulinumtoxinA \[Myobloc/Neurobloc\]) injection for CD due to non-response or suboptimal response to BoNTA (applicable only to de novo subjects)