Occurrence of Dysphagia Following Botulinum Toxin Injection in Parkinsonism-related Cervical Dystonia: A Retrospective Study

Background: The aim was to compare the occurrence of post-injection dysphagia in parkinsonism-related cervical dystonia (PRCD) versus cervical dystonia ( CD) of other etiologies (non-PRCD). A secondary objective was to explore potential clinical differences between PRCD and non-PRCD and their respective responses to botulinum toxin (BoNT). Methods: A cross-sectional chart review was carried out of patients treated for CD with Onabotulinumtoxin A at the University of Florida. We collected demographic information, dose of BoNT injected, patient-reported presence of dysphagia as a side effect, patient-perceived duration of benefit and efficacy according to the Clinical Global Impression Scale (CGIS). Results: Of the 144 patients included, 24 patients were diagnosed with PRCD and 120 were diagnosed as non-PRCD. Data analysis showed no significant differences in number of weeks of benefit from BoNT (PRCD 9.1 +/- 3.7 versus non-PRCD 9.4 +/- 3.7 weeks, p=0.830), BoNT dosage (PRCD 235.0 +/- 95.6 versus non-PRCD 263.7 +/- 101.3 units, p=0.181), median CGIS score (median-2 or "much improved'' for both groups, p=0.88), or the presence of dysphagia after BoNT (PRCD 17% versus non-PRCD 19 %, p=0.753, n=132). In a subgroup analysis of the non-PRCD group, patients who experienced dysphagia were older than those who did not (63.9 +/- 8.9 years versus 58.1 +/- 14.4 years, p=0.02). Discussion: Despite an increased baseline risk of dysphagia in patients with PRCD, BoNT appears to be equally safe and equally beneficial in PRCD and non-PRCD patients.