Effect of recurrent onabotulinum toxin A injection into the salivary glands: An ultrasound measurement.

OBJECTIVES/HYPOTHESIS Onabotulinum toxin A (OBTXA) injection is a well-established therapeutic option for the management of drooling. Many of the children treated undertake repeated injections every 3 to 6 months. We aimed to assess quantitative salivary gland changes via ultrasound imaging after intraglandular injection of OBTXA for sialorrhea treatment in children, as a method that suggests permanent changes in glandular size can cause a decrease in functionality or atrophy. STUDY DESIGN Case-control study. METHODS The parotid and submandibular glands of 22 patients with sialorrhea with previous repetitive OBTXA treatments were measured via ultrasound. These were compared with a control group of 38 healthy children. RESULTS A total of 60 patients were included in the study (38 boys, 22 females). Body mass index, sex, and age were defined as confounders. The mean age was 7 years (standard deviation [SD] ±2.3 years) and 9 years (SD ±3.8 years) for treatment and control groups, respectively. There were no postinjection complications. We found significant decrease in the size dimensions (surface area and depth) of both submandibular glands and one parotid gland in the treatment group (P < .05). Significant smaller anterior-posterior dimension of the submandibular glands (P < .01) was also found. CONCLUSIONS The chronic use of intraglandular OBTXA reduced the size of the salivary glands measured ultrasonographically. Results were correlated with clinical outcomes. Pathological studies should be done to correlate whether ultrasound changes result in atrophy or apoptosis of the glands. LEVEL OF EVIDENCE 3b