Drooling (or dribbling), where saliva is present beyond the lip margin, is normal in babies and infants. As neurological control of the tongue and bulbar musculature develops, salivary “continence” normally occurs by 15–18 months, though a high number of typically developing children will continue to drool up until the age of 3 years, especially during eating and drinking. The ability to control saliva develops alongside normal feeding and oral-motor control. It is certainly considered abnormal to have problems with saliva control (sialorrhoea) beyond the age of 4 years. The unconscious swallowing of saliva is a complex process and is indeed one of the most intricate motor functions in a human. The coordination of over 25 pairs of bulbar muscles is vital to maintain the integrity of the swallow reflex. Acute sialorrhoea may be associated with inflammation or infections of the oral cavity or dental problems causing hyper salivation. Some anticonvulsants, such as clonazepam and clobazam, may also increase saliva production (hypersialia). Chronically, it is seen in children with a general physical disability or a specific oral-motor difficulty.
Drooling is normally due to inefficient tongue and/or bulbar control rather than poor lip closure or hypersialia in isolation. This can be a multifaceted dysfunction, with lack of external somatic and intraoral sensation being involved as well as the impaired motor coordination in or around the mouth. Head control and the posture of the individual are obviously also important. The overall prevalence of significant chronic drooling in childhood is put at up to 0.6%.The commonest population group with severe and persisting difficulty is children with quadriplegic cerebral palsy where the prevalence rate is as high as 30–53%.
Oro motor exercises
If an individual child has appropriate levels of attention and compliance, specific oral-motor exercises can be helpful. Some children, if they are able to follow directions, can achieve control of their saliva with the help of tongue and mouth exercises organized by speech and language therapists. It often takes a considerable period of time to improve the situation, and the control gained is often very dependent on the level of concentration of the child and what other tasks are being performed at the same time. Programs may include measures to improve oral-facial tone, increase sensory awareness and develop voluntary control of movement.
Short-term effects on facial tone are reported following oral-facial facilitation techniques such as brushing, vibration and manipulation, but there is little published research confirming longer-term effects on saliva control. Some of these techniques suggested in the literature, including “icing” and use of vibration, where sensory stimuli are applied to the facial muscles, may have potential harmful effects if applied with inadequate knowledge. The family and carers must “buy in” to oral motor programs too as the child will need considerable long-term encouragement and support in order to gain any degree of success. The evidence base for oral-motor therapy is very limited, particularly in children with severe disabilities, and clinical experience suggests this approach is only applicable to children with mild to moderate oral dysfunction, good cognitive skills and a high level of motivation. The use of biofeedback systems to improve background swallowing frequency has also been looked at in some centers with a degree of success. Here, an auditory cue is used to remind an individual to swallow, helping them to develop a better pattern of control.