an adult produces about 1.2 litres of saliva a day , mainly from three pairs of major salivary glands and from minor glands in the oral cavity and palate .
the relative contributions to volume are minor glands 5% , sublingual glands 5% , parotids 30% , and submandibular glands 70% .
saliva lubricates food to assist in chewing , and the swallowing process contains digestive enzymes and has a role in dental health .
sialorrhea (  drooling  ,  dribbling  , and  drivelling  ) is the involuntary escape of saliva from the mouth .
in contrast to excess saliva production ( salivation ) it implies an inability to retain saliva due to lip incontinence , or to decreased oral sensation , a defective oral stage of swallowing , an open bite , poor posture and neck flexion , or a combination of those factors .
drooling is not uncommon in normal children ( usually boys ) up to the age of five .
in contrast , pathological drooling is a major cause of poor quality of life in individuals with major neurological disability . strokes , parkinson 's disease , and motor neurone disease can be a cause of sialorrhea in late adult life . of greater significance
is that drooling can be a major and potential life - long disability in physically and intellectually impaired children .
the cause is not overproduction of saliva   but impaired lip control , causing a delay between the suction and propelling stages of the oral phase of swallowing .
consequently , saliva from the sublingual and submandibular glands pools in the anterior floor of mouth and spills out .
the spectrum of drooling severity ranges from minimally affected to severe and persistent when it can have major negative effects on the physical and social well - being of the individual as well as on their family , caregivers , and peers .
the physical effects can be cracked lips , odour , and soaking of bedding , clothes toys , school books , caregivers , and peers .
it can lead to social isolation and , in individuals with less cognitive disability , self - consciousness and depression .  
attempts to treat pathological drooling can be summarised as behavioural ( speech therapy , physiotherapy ) ,  pharmacotherapy , and surgery . in some centres physiotherapists ,
occupational therapists and speech - language  therapists offer a combination of techniques such as posture / positioning , oral - motor therapy , and behaviour modification techniques to increase sensory awareness and voluntary swallowing .
this approach is time - consuming , the relapse rate is high , and it only suits a small group of well - motivated subjects .
traditional pharmacological treatment has been anticholinergic drugs to inhibit salivary production , either as atropine oral drops or scopolamine patches .
the first surgical treatment for drooling was relocation of the parotid ducts , followed by the additional removal of the submandibular glands .
later , even the more radical bilateral division of the parotids ducts and removal of the submandibular glands was advocated [ 7 , 8 ] , and more recently a
 four - duct ligation  . in the 1970s , neurectomies ( division of the chorda tympani nerve and tympanic plexus in the middle ear ) were attempted ( figure 1 ) [ 1012 ] .
these were mainly in adults , with equivocal efficacy , late relapse , and attracted the criticism that it entailed an operation on a normal ear with loss of taste sensation if both were divided treated .   in 1974 , ekedahl from scandinavia described a new operation   for sialorrhea  relocation of the submandibular ducts to the tonsillar fossae .
99  mtc isotope salivary gland uptake studies indicated functioning glands and the likely normal passage of saliva to the oropharynx .
its preservation of normal ( but diverted ) salivary function and its simplicity were appealing .
subsequently it has become ( with refinements ) the surgical technique of choice for severe drooling .
the main advocate has been crysdale in canada [ 1416 ] , others in australia [ 8 , 17 , 18 ] , and elsewhere [ 1921 ] .
in a small series of children and teenagers with sialorrhea treated ( 19932011 ) by surgery , the indications and results were analysed from hospital inpatient , outpatient , and specific database records .
all had severe sialorrhea , requiring changes of clothes during the day , despite extra measures such as bibs and scarves .
the operation is performed under general anaesthesia with nasal intubation to enhance access to the tongue and floor of mouth ( figure 2 ) .
a mucosal island around the duct opening is made , and the floor of mouth mucosa opened to allow dissection of the the duct to just above the submandibular gland .
a vascular tape is passed through , the mucosal island and duct attached and then pulled through to the tongue base , where it is sutured .
all steps of the operation are shown in the videoclip , see supplementary materials available at doi:10.5402/2012/364875 ( video 1 ) .
, care givers were asked to grade the efficacy on a linear scale : 025% , 2550% , 5075% , and 75100% .
the final efficacy ( percentage improvement ) median score was 75% ( range 50%100% ) ( figure 3 ) .
for severe drooling , it is unlikely that behavioural techniques or traditional pharmacotherapy effective , or at least practical for a lifetime .
the earliest surgical treatments were radical [ 58 ] with undesired consequence of painful swelling of salivary glands and a likely near total lack of saliva .
ekehdahl 's   report of relocation of the submandibular ducts was an original and appealing advance 
elimination of saliva pooling in the anterior floor of mouth , but insuring its diverted presence in the pharynx to assist the swallowing process , for life .
the earliest advocates of submandibular duct relocation in canada and usa reported favourable drooling rates [ 15 , 16 , 22 ] , but there were problems . in his early paper  how i do it , 
 consequently crysdale advocated automatic removal of the sublingual glands , and this has become standard practice . in this small series of paediatric patients with severe sialorrhea treated surgically , the majority had bilateral submandibular duct relocations with concurrent removal of sublingual glands .
unexpected findings were the variability in the size ; symmetry or the absence of sublingual glands , the absence or ectopic location of submandibular ducts ( table 3 ) . in some individuals ,
the sublingual glands are extensive and presumably contribute a relatively large amount of the saliva volume .
therefore , the automatic removal of sublingual glands is logical and accounts for the absence of ranula formation in this series .  
a new development in pharmacologic treatment for drooling has been the use of botulinum toxin injected into the salivary glands .
following the first report on its efficacy when injected into the parotid glands in an adult with motor neurone disease , it has been used as a temporary treatment in other adult neurological disorders and in children with cerebral palsy to control sialorrhea .   in summary
, pathological sialorrhea can have a major effect on life quality of individuals with neurological and intellectual disability , particularly in cerebral palsy where it is likely to be a lifelong problem .
when it is severe , behavioural and systemic pharmacological treatments are usually not effective or sustainable .
however in children , its use might be justified as a demonstration of the benefits of salivary control .
bilateral relocation of the submandibular ducts and removal of the submandibular glands has evolved into being the logical contemporary surgical treatment for this distressing condition . in this small series
 the causes of severe sialorrhea ( drooling ) are reviewed , and in particular in children in whom it can become a life - long disability . the history of medical and surgical treatments is discussed . 
 a major advance has been the surgical relocation of the submandibular gland ducts with removal of sublingual glands . 
 the results of this operation , technical considerations , and its outcomes in 16 children are presented . 
 there were no significant complications . 
 caregivers judged the efficacy with a median score of  
 75%  improvement . 
 the technique has become the most logical and reliable surgical treatment for drooling , with very good control in most cases . 
 in contrast to  botox  its effects are permanent . 
1. Introduction
2. Methods
3. Results
4. Discussion