170 CHAPTER 8 controversial. In these cases, duct ligation (DL) or bilateral submandibular gland excision (SMGE) are alternative techniques. Success rates of the afore mentioned procedures are generally similar (i.e. 63%-81%), with SMDR having the best results.15,17-19 Nevertheless, a significant amount of patients after unsuccessful surgery suffer from persistent of recurrent drooling. Recurrence or persistent severe drooling may be due to the multifactorial etiology of drooling. Although the underlying condition, use of benzodiazepines, gastroesophageal reflux disease (GERD), head posture and degree of dysfunctional oral motor control are suggested as potential influencing factors for therapy outcome, only anteflexion proved to predict surgical treatment success.6,20,21 On the contrary, recurrence after intervention can also be due to surgical failure. For example, surgical failure of SMDR can be caused by relocating the ducts not close enough to the oropharyngeal isthmus. In addition, surgical failure after DL can be caused by e.g. failing clips or development of a collateral route.19,22 If there is a surgical explanation of relapse after duct ligation or duct rerouting, bilateral submandibular gland excision should theoretically solve these failures. An alternative salivary pathway formation in case of submandibular DL, or inadequate relocation of the ducts in case of SMDR as an alternative could be suspected as a cause of relapse.19,22. However, when drooling remains refractory to re-intervention with SMGE, this suggests a different mechanism. Proposed mechanisms are: a compensatory salivation of the parotid glands, or a yet unrevealed predominant position of other contributory clinical variables (e.g. underlying conditions, poor posture, severe dysfunctional oral motor control).20 In this study, we present a case series of patients with recurrence of anterior drooling after primary submandibular duct surgery (duct ligation or submandibular duct relocation). We aimed to investigate if submandibular gland excision (SMGE) or parotid duct ligation (PDL) as a re-intervention is beneficial for anterior drooling and hypothesized that either the submandibular glands (surgical failure) or underlying clinical variables (e.g. compensatory parotid salivation, lip seal etc.) are the main cause for persistent drooling.
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