When the Consortium on Drooling1 was held in 1990, treatments for drooling were on almost nobody’s radar screen. We reviewed and annotated the entire international literature on the subject; it didn’t take long. We tried to gather everyone we could identify in North America with a special interest in treating sialorrhea. Pioneers in surgical approaches participated including Charles Gross (tympanic neurectomy) and Milton Edgerton (submandibular duct transposition). Several sessions were led by the co-directors of the Drooling Control Clinic (both dentists) at the Hugh MacMillan Rehabilitation Centre in Toronto, where their surgeon (William Crysdale) had more experience than anyone in the world. No one was very well-versed in oral drug therapy (the surgeons simply dismissed it) and botulinum toxin type A (BoNT-A) had not yet come on the scene. Parents and adult patients were part of the discussions. National Aeronautics and Space Administration (NASA) engineers were there (‘If you can manage body fluids in space, why can’t we control drooling on earth?’).
So where are we 20 years later? Drooling is now readily acknowledged and routinely addressed in the clinic. Publications on the topic have greatly increased in quantity and improved in quality. Surgical approaches continue to be heterogeneous and no one procedure has emerged as the most effective.2 BoNT-A is widely promoted and oral drugs are more likely to be given a trial. We now debate which treatment is better.
The comparative study by Scheffer et al.3 appears to have selected a population of relatively poor BoNT-A responders and then intervened with surgery. There were 133 children initially treated with BoNT-A. Only 20 opted for surgery. Despite the authors’ contention that the groups are not different on the basis of drooling quotient numbers, the surgical sample is a ‘different’ (biased) subset of the larger group. The relatively low BoNT-A success rate cited in the paper reinforces this viewpoint; in other words, I suspect the better responders are not represented among the surgical patients. The conclusion that the surgical procedure employed is more effective than BoNT-A is only justifiable in the population studied. Furthermore, this is a mildly involved cerebral palsy cohort: 10 out of 19 were at Gross Motor Function Classification System (GMFCS) levels I, II, or III. This makes the low BoNT-A response rate stand out even more and the surgical response rate less impressive in my opinion. Although no one has published the data, in my clinical experience children at GMFCS levels I and II are less afflicted with problem drooling than their counterparts in levels IV and V.
An issue related to the above discussion is the outcome measure. As in 1990, ideal outcome measures remain elusive. The drooling quotient is a useful quantitative measure but should be augmented with some measure of parent/patient satisfaction. Given the highly variable nature of drooling in cerebral palsy populations, quantitative measurement systems have always been problematic in drooling studies, and some type of measure (even though subjective) of parent perception of outcome is valuable to augment objective measurements. Thus, 85% of the original cohort reported by Scheffer et al. were content enough with their treatment (or aversive enough to the thought of surgery) to continue with what they were doing. Some must not have been surgical candidates. The remaining individuals who agreed to surgery would likely have been relatively low on a satisfaction scale.
So what is the best alternative? We know that a variety of surgeries work and that anti-cholinergics, given orally or by injection (BoNT-A), also work. The authors of the article perceive BoNT-A and behavioral therapy as providing ‘effective, minimally invasive drooling relief.’ They remain dismissive of oral anti-cholinergics, stating BoNT-A ‘has emerged as the only serious alternative to surgery…’ The successful use of oral anticholinergics is well documented in the literature to be at least as effective as BoNT-A.4 In truth, there are no convincing data to support any one treatment over the other. The study that needs to be undertaken is a head-to-head comparison of BoNT-A and the more traditional oral anticholinergics – glycopyrrolate, hyoscyamine, or trihexyphenidyl. Meanwhile, I continue to recommend oral drugs and behavior modification interventions first.4,5 BoNT-A comes next and surgery remains a last resort, following a least to most invasive sequence and cautioned by the fear of potential irreversible side effects.6 Scheffer et al. rightly point out that the procedure they favor (submandibular duct relocation) is not suitable for children at high risk for aspiration.