Negative effects on oral motor function after submandibular and parotid botulinum neurotoxin A injections for drooling in children with developmental disabilities

To evaluate negative effects on oral motor function after concurrent submandibular and parotid (four-gland) botulinum neurotoxin A (BoNT-A) injections as a treatment for paediatric drooling. This was a retrospective cohort study of 125 children (median age 7 years 7 months [interquartile range 4 years 5 months]) with developmental disabilities, including cerebral palsy, treated with four-gland injections. Most children (90.4%) were previously exposed to submandibular injections. Frequency, severity, and duration of negative effects on oral motor function (i.e. saliva swallowing, eating, drinking, articulation) were evaluated and compared to a reference cohort treated with submandibular injections. Negative effects on oral motor function were reported in 45 children (36.0%), predominantly manifesting as eating-related problems (64.4%). Most negative effects (62.2%) were classified as mild and resolved within 4-weeks post-injunction (53.3%). Compared to the reference cohort, frequency (36.0% vs 33.0%) and duration (53.3% vs 53.6% resolving within 4 weeks) of negative effects were comparable, although problems were more often moderately severe (33.3% vs 10.1%). While negative effects on oral motor function were relatively common after four-gland BoNT-A injections, most problems were mild and resolved promptly. No substantial differences to a reference cohort treated with submandibular injections were observed, although further research should establish the generalizability of these findings in a treatment-naive population. Nevertheless, when submandibular injections prove ineffective, clinicians can confidently consider four-gland injections.