Cervical Dystonia Subtype, Severity Impacts OnabotulinumtoxinA Utilization
Torticollis was the most common predominant cervical dystonia presentation subtype at injection 1, followed by laterocollis.
Pinky Agarwal, MD, FAAN
Additional real-world data from the CD PROBE study (NCT00836017) suggest that cervical dystonia (CD) subtype frequency differs by CD severity and that severity impacts onabotulinumtoxinA (Botox; Allergan) utilization, with higher dosing observed over time coinciding with disease severity.1
The findings were presented at the International Parkinson and Movement Disorder Society (MDS) Virtual Congress 2021, September 17-22, by Pinky Agarwal, MD, FAAN, neurologist, Booth Gardner Parkinson’s Care Center, Evergreen Health. All told, the median total dose across all severities increased from injection 1 to injection 3 (mild: 138 U to 165 U; moderate: 183 U to 200 U; severe: 200 U to 285 U, respectively). Safety data collected at each treatment session showed no new safety signals.
CD PROBE, a multicenter, prospective, observational registry, included 1046 patients enrolled received up to 3 treatments of onabotulinumtoxinA according to the standard of care at each clinician’s practice. Among the cohort, 350 individuals completed treatment sessions, 54.3% of which had moderate severity at injection 1. The remaining 32.6% and 13.1% had mild and severe cases of CD, respectively.
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Regardless of severity, torticollis was the most common predominant presentation subtype at injection 1, observed in 44.7%, 55.8%, and 63% of mild, moderate, and severe cases, respectively. Laterocollis, the second most predominant presentation subtype, was found in 42.1% of mild cases, 32.6% of moderate cases, and 26.1% of those with severe cases of CD. At the conclusion of the study, investigators found that the median onabotulinumtoxinA dose to treat torticollis (Injection 1: 160 U, Injection 3: 200 U) and laterocollis (Injection 1: 170 U, Injection 3: 200 U) increased over time.
In total, 112 patients (32%) reported at least 1 adverse event (AE), the most common being dysphagia (8.3%) and muscular weakness (8.3%), followed by headache (2.9%) and neck pain (2.6%). There were 13 serious AEs reported by 81 patients (23.1%), none of which were treatment related.
Original data from CD PROBE were published in 2014, with results indicating robust improvement in clinical ratings among patients with CD following onabotulinumtoxinA treatment. Among individuals who completed all assessments (n = 479), the mean Toronto Western Spasmodic Torticollis Rating Scale Total score decreased from 39.2 at baseline to 27.1 at final visit (P <.0001). Additionally, a high percentage of physicians reported improvement in Clinician Global Impression of Change after initial assessment, which significantly increased at final assessment (91.2% vs 95%; P <.0001).2
OnabotulinumtoxinA has been granted multiple FDA indications since its original approval, most recently for an expanded indication to treat 8 additional new muscles in patients with upper limb spasticity.3 Among them include muscles of the elbow and forearm (brachialis, brachioradialis, pronator teres, and pronator quadratus), intrinsic hand muscles (lumbricals and interossei), and thumb muscles (flexor pollicis brevis and opponens pollicis).
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