Botulinum Injections for Idiopathic Cervical Dystonia: a Longitudinal Study.

Botulinum toxin (BT) injections into the cervical muscles are an effective and commonly practiced treatment approach for cervical dystonia. In this retrospective longitudinal study, we collected data from the Sheba electronic medical records on consecutive patients with idiopathic cervical dystonia (ICD), treated regularly with periodic BT injections between the years 2008-2020. All treatment visits were analyzed regarding type of toxin, dose injected, and clinical outcomes. The vast majority of patients were treated with abobotulinum toxin A. Sixty-four ICD patients (51 (79.7%) females, onset at age 45.8 ± 13.7 years) were treated over 17.1 ± 13.9 (range 3 to 49) visits per patient; BT treatment efficacy increased gradually from initial treatment sessions to visit 13, when it achieved a steady state. While the subjective report of percentage improvement and its duration were around 78.9 ± 17.1% for 2.8 ± 1.0 months, respectively, the dose of BT increased significantly over the years (p = 0.006). Side effects (SE) were not rare, and commonly recurred after subsequent sessions and were usually mild and short-lasting, with dysphagia being the most common (~17.5%), followed by neck/arm weakness (11.9%) and cervical pain (8.9%). Repeated injections of BT for ICD remain beneficial for patients over several years of therapy, and despite mild SE, patients tend to adhere to a 3-4 months interval schedule.