Thickened saliva after effective management of drooling with botulinum toxin A

Abstract

AIM The aim of this study was to evaluate the rheological properties of saliva after submandibular botulinum toxin type A (BoNT-A) injections.METHOD We enrolled 15 children (11 males and six females; age range 3-17y, mean age 9y 10mo) diagnosed with spastic (n=9) or dyskinetic (n=6) quadriplegic cerebral palsy (CP); Gross Motor Function Classification System level IV or V; and two children with intellectual disability (IQ <70) who experienced moderate to severe drooling. Salivary flow rate and drooling quotient were measured at baseline and at different times after BoNT-A injections up to 24 weeks. The mucin concentration of saliva was analysed before and after BoNT-A treatment.RESULTS Both submandibular salivary flow rate (baseline 0.38mL ⁄ min; 24wks after injection 0.26mL ⁄ min) and drooling quotient (baseline 42.5%; 24wks 28.80%) were substantially reduced, with a concomitant increase in mucin concentration within 8 weeks after BoNT-A injection (from 0.612 to 1.830U ⁄ mL). The parents of nine children observed thickened saliva. Swallowing and chewing were problematic in seven children. Two of these children needed treatment with mucolytics because of pooling of thickened saliva in the throat. INTERPRETATIONWhen making decisions about the use of BoNT-A, the risk of problems with masticatory and swallowing functions as a result of thickening of saliva after BoNT-A treatment should be taken into account.Local injection of botulinum toxin type A (BoNT-A) into the salivary glands is used to prevent drooling. BoNT-A causes a temporary inhibition of SNAP-25, the presynaptic acetylcholine exocytotic synaptosome-associated protein which has a molecular weight of 25kDa. As a result, the gland's capacity to secrete water is depressed. After BoNT-A injection, basal saliva secretion is usually sufficient to moisten the oral cavity and to facilitate swallowing of food. Incidental side-effects have been reported, such as flu-like symptoms lasting for less than 2 days, swallowing difficulties, viscous saliva and dryness of the mouth, transient slight weakness of the masseter muscle or mouth openers, and, rarely, jaw dislocation. [1][2][3][4][5][6] Human saliva serves multiple functions in the oral cavity, including moistening of food, facilitation of mastication and swallowing, and cleaning and lubrication of the oral mucosa. 7 The seromucous sublingual, submandibular, and palatine glands secrete mucins that coat and protect the epithelial tissue of the oral cavity and give the typical viscoelastic character to saliva. Salivary mucins are primarily wetting agents that play a role in lubricating the tissue-environmental interface to reduce friction. 8,9 We have observed that in some children the saliva becomes sticky after intraglandular botulinum toxin injection and postulated that sticky saliva may cause swallowing problems as a result of an increase in protein concentrations and hence salivary viscosity, resulting in greater friction. 10 Previous studies have focused on the effect of BoNT-A on salivary proteins such as se...

The Experience of Treating Drooling with Repeated Botulinum Toxin Injections

“…One patient had swallowing problems due to the diffusion of BTX-A into the surrounding muscles, leading to temporary muscle weakness. This is a known adverse effect of BTX-A; it has been documented in other studies as well [12,13]. In a larger study (175 BTX-A injections), dysphagia was reported in 3% of injections [12], which is approximately the same range as in our study.…”

“…In a larger study (175 BTX-A injections), dysphagia was reported in 3% of injections [12], which is approximately the same range as in our study. In a study of 17 patients, swallowing problems were documented in 41% (7/17) of children with cerebral palsy who received injections of BTX-A to the submandibular glands, but the authors proposed this was mainly due to a thicker composition of saliva [13]. Excessive dryness of the mouth is also possible after BTX-A treatment [14].…”

Negative effects of submandibular botulinum neurotoxin A injections on oral motor function in children with drooling due to central nervous system disorders

“…Higher salivary viscosity after BoNT-A injections may result in problems with intraoral processing of (solid) food. 20,21 Indeed, we found a significant association between increased salivary viscosity and the occurrence of adverse effects. Concerning oral motor function, the second potential cause of BoNTrelated problems is the diffusion of the toxin outside the salivary gland leading to muscle weakness.…”

Salivary gland botulinum toxin injections for drooling in children with cerebral palsy and neurodevelopmental disability: a systematic review

“…d Six studies reported on the same cohort of patients: Jongerius et al. (A) and (B) reported on two different outcome measures in the same cohort of patients; Scheffer et al (B) later incorporated the Jongerius et al patients as well as Scheffer et al 2010 (A) patients; Erasmus et al 25,31 performed secondary analyses on the Scheffer et al (B) cohort of patients. SMG, submandibular gland; BoNT, botulinum toxin; NS, not specified; GA, general anaesthetic; MU, mouse units of BoNT‐B; PG, parotid gland.…”