Title: Expiratory Muscle Strength Training for Drooling in Adults with Parkinson’s Disease
Authors: Cocks, Rafols, Embley, & Hill
Year of Publication: 2022
Design Type: Single-cohort study
Purpose: “This study explored the effect of an alternative therapy approach for drooling that aimed at improving the swallow, expiratory muscle strength training (EMST)”
Population: Adults with Parkinson’s Disease from Australian hospital with self-reported difficulty with drooling
Inclusion criteria: confirmed diagnosis of Parkinson’s (according to the UK Parkinson’s Disease Society Brain Bank Diagnostic Criteria)
Exclusion criteria: inability to understand written/spoken English; score of <17 on MMSE for cognitive impairment; botulinum toxin injections for drooling within 8 months; and/or co-existing diagnosis that was likely to impact sialhorrea/swallowing
As a kid, we start to form our creative and curious imaginations when we begin to use a common object (e.g. toy hammer) as a completely different and novel function from its intended purpose (e.g. using a hammer as a cane). We might even do this long after when using a hairbrush as a microphone in our pretend concert in our room (🙋♀️guilty!) or a broom to get something small out from underneath the bed.
Thinking along these lines of creativity, the authors did just this for an innovative study that questions if a very well known exercise program/device that’s confirmed to improve various swallowing safety deficits can also be used to subsequently improve a different impairment for a very needed population.
Get ready to get your imagination thinking caps on for this one folks, because from clinicians who work closely with this population to those who aren’t as familiar, I’m sure everyone’s mind will be bursting with the possibilities by the end!🤯
To help everyone be on the same page, some general information about this incredibly special population and its often accompanied drooling:
“Sialorrhea or drooling is a common consequence of Parkinson’s disease (Parkinson’s) with an estimated prevalence between 32 and 74%. The cause of sialorrhea in Parkinson’s is not due to increased saliva production, but rather due to a combination of a number of factors including impaired swallow and decreased lip closure.”
“Sialorrhea has been ranked as the third most bothersome symptom in advanced Parkinson’s and is associated with poor health-related quality of life (HRQoL) and social isolation.” p.1
Along with this often intrusive impairment, the PD population has a significant association for impaired swallowing at some point in their disease progression along with impaired peak cough flow which also often results in increased risk of developing a pulmonary complication such as aspiration pneumonia (which has been indicated as this population’s leading cause of death😱).
While there may be various clinical remedies, from chewing gum to reminder apps, the most common treatment for sialorrhea remains to be botulism toxin injections to the salivary glands in order to reduce the amount of saliva produced. However, this can have its own side effects and complications such as difficulty chewing, increasing dyspagia symptoms, and/or creating a drier oral cavity (which we all know can lead to an increase in oral bacteria=not good for anyone, anywhere, anytime) .
So why must we keep subjecting this population to an intervention if the benefits may not outweigh the ultimate costs? If you’re sitting there wondering what else we could do, you’re not alone!
And that’s just what the authors sought to find out:
“As sialorrhea in Parkinson’s is due, at least in part, to decreased impaired swallowing and lip closure, it follows that treatments that result in improved swallowing and improved lip strength may also result in reduced sialorrhea.” p.1
Hmm…what treatment could we turn to to target all these things. . .?
And again, in case anyone isn’t familiar with this progressive loading training device, the authors give you a great recap along with the primary basis (with all the great references to match of course!🤓):
“The main muscle responsible for lip closure is the orbicularis oris. It consists of both deep and superficial fibres. Therapy that targets lip strength has been found to result in increased lip closure. Furthermore, previous research has found that resistance training targeting the orbicularis oris has resulted in increased lip strength in participants who have had a stroke.”
“Previous research has found increased activity of the orbicularis oris during EMST. As such, this action should, in theory, serve to strengthen the muscles involved in lip closure and those involved in forced expiration.” p.2
While there is current evidence that test and suggest benefits for the PD population when it comes to reduced PAS scores (improved airway safety/protection) and peak cough flow for swallow function, the same cannot be said when looking to aim for improved lip closure and sialorrhea. So the authors measured all of these things accordingly with some pretty gnarly patient-reported outcome measures and some standardization included😉.
Seriously though, get ready to add some PROMS to your list as you see fit (or for the future!) and jot down the details. And why am I able to know all these? Because the authors included a detailed scheduled protocol for us clinicians, should we so boldly and bravely decide to reach out and help get more data for more evidence!🤩
The authors had the whole protocol laid out as an easy-to-follow guide:
- 4 pre-training assessment sessions
- over 1-2 weeks
- 20 sessions with EMST (intervention)
- over 6-8 weeks
- 2 supervised face-to-face sessions with SLP per week
- 3 at home sessions/unsupervised per week
- 2 post-training assessment sessions
- completed immediately following completing of intervention component
Since they were primarily interested in a reduction in sialorrhea while also questioning if improved swallow function could be a result fromworkng on peak expiratory cough flow and lip strength, ya gotta ask, how in the world did they figure out how to measure all that??🤔
Well, that is why researchers’ hours may consist of investigating all of that, while ours consist of implementing such measures (among many, many other things of course😉).
Before you start imagining the authors weighing or analyzing amounts of drool, there seems to be no quantitative objective measures such as this, and the authors make sure to add “currently there are no other published measures of sialhorrea suitable for people with Parkinson’s with superior psychometric properties.” But, the best current option is a questionnaire that “has been found to be valid and reliable,” the Sialorrhea Clinical Scale for Parkinson’s Disease (SCS-PD).
Swallowing Severity & Quality of Life Measures:
“The Mann Assessment of Swallowing Ability (MASA) was used to assess severity of swallowing function and the Swallowing Quality of Life Questionnaire (SWAL-QOL) was used to assess health-related quality of life (HRQoL) associated with swallowing.”
“These assessments are reliable, valid and responsive. Lower scores on the MASA and the SWAL-QOL represent greater difficulty with swallowing and impact on HRQoL.” p.3
The MASA was completed twice (1 week apart) during the pre-training phase in order to get a double baseline, while the SWAL-QOL was completed only once during the pre-training. Both measures were completed once at the post-training phase.
Lip Strength & Peak Expiratory Flow Measures:
“Lip strength measures were collected using the Iowa oral performance instrument (IOPI). Peak expiratory flow was measured during a cough manoeuvre using a hand-held flow meter (EasyOne spirometer).” p.3
Both of these measures were taken at each of the 4 pre-training sessions (best out of 10 attempts that was within 10% of at least to others was accepted). Both were taken once again for the post-training phase.
Training Satisfaction Measure:
After the interventional study was over, all participants were also asked to complete a 10-point Likert scale rating their level of satisfaction with the training.
This is something that personally I feel is hugely underrated and under-studied because if our patients don’t like a program or it’s too hard to follow resulting in incompletion or poor carryover, then what’s the point? (For further proof, checkout Dr. Krekeler’s important work on this very issue of adherence)
Whether you’ve never heard of any of these measures, have been trying to get them into your clinical practice wherever you may be, or if you’ve been using these for some time, these are some things to keep saved somewhere in your mind, desk, or clipboard, particularly for this population.😉
Before we get into the nitty gritty results, let’s just first take a quick moment to see how the authors did what they did, because guys, it’s not nearly as complex and complicated as it seems!
For the EMST 150 device, they went off the American College of Sports Medicine’s position on principles of resistance training:
“Specifically, it is recommended that older adults (and otherwise sedentary people) commence resistance exercise at loads equivalent to 40 to 50% of maximum. Hence for the initial training session, we aimed to have participants reach a load equivalent to 50% of the peak pressure that could be generated (by their expiratory muscles).” p.3
And remember their interest on satisfaction with the training? Well, the authors give a pretty compelling rationale to adjust training loads according to symptoms due to an all-too-realistic daily dilemma we clinicians also face, “Although it is possible that higher training loads could have been tolerated and produced greater gains, this may have compromised their satisfaction with the training programme.”
The rest of the protocol with EMST device looked like this:
- seated position
- instructed to breathe at their usual rate/depth for interval training:
- Single forced expiration, followed by 15 second rest period
- Repeated 25 times
- 1 minute rest break every 5 breaths
- Rated perceived exertion with BORG 0-10 category scale
- Only 1 participant required an added nose clip (for initial 2 in-person sessions only)
“Training loads were progressed as quickly as possible with the goal of having the load during the final two-minute work interval perceived as ‘very hard’ (7/10 on the Borg scale) with participants unable to consistently maintain lip closure during their last few expiratory efforts.” p.3
While there’s no mention if caregivers were trained as well or if they were needed at all to assist for at-home sessions, the overall picture may look pretty similar and appropriate enough to implement in our planned therapy sessions in clinics, homes, or patient rooms!?
Now that we know what they did, how they did it and why, let’s put it all together!
Basically, when comparing pre/post training measures, time had an effect on EVERYTHING!
“the post-training score was significantly less than both pre-training scores. This indicated that self-reported saliva difficulties significantly decreased post-training…” p.4
“In people with Parkinson’s, the results of this single-group study demonstrated that the measure of sialorrhea was stable over the pre-training assessment period but improved following a period of EMST.” p.5
While one of the secondary aims for lip closure saw a bit more variability in terms of post-training a couple of the pre-training sessions (I’m suspectful of some kind of possible training effect?), the overall results still showed significant differences from pre-post training. And remember those swallow severity and quality of life measures? Both MASA and SWAL-QOL scores improved (increased) following the EMST intervention. The authors make sure sure to drive the whole point home for us:
“Furthermore, unlike botulinum toxin injections which do not treat the cause of sialorrhea, EMST was found to result in improvements to some of the underlying factors that contribute to sialorrhea, namely reduced swallow efficiency and reduced lip closure.”
“The results of this research extend the results of previous studies on EMST in Parkinson’s by showing that this training produced within-group differences in swallow function, thus targeting the pathophysiological mechanism underlying drooling.” p.5
Finally, a critical component to help reduce the risk of aspiration pneumonia, airway protection measures by peak cough mimicked these encouraging results as well and lead the need for further research:
“Our data also suggest that there is an important additional benefit of using EMST for sialorrhea treatment, improvement in peak cough flow measure was significantly higher than each pre-training measure.”
“The impact of EMST on aspiration pneumonia risk is yet to be systematically explored. However, as EMST targets physiology responsible for both swallow function and peak cough flow, and aspiration pneumonia is usually as a result of aspiration of contents due to an impaired swallow and a reduced ability to expectorate aspirate, it is likely that EMST will result in a reduction in aspiration pneumonia risk. This should be explored in future research.” p.5
As a cherry on top🍒, when it came to the satisfaction ratings on the overall training program:
“All participants who completed the study reported being satisfied with the training programme. Twelve participants gave the maximum rating of 10 (very satisfied). The remaining four participants gave a rating of 9. All participants indicated that they were highly satisfied with EMST as a treatment for sialorrhea…This suggests that the treatment approach was well tolerated by participants and was not considered burdensome.” p.4-5
This is all great data and evidence without a doubt! However, the authors do add the limitations cannot be overlooked, and there are some other questions that remain unanswered as well.
First, it can easily be pointed out that half the measures are self-reported or observational-type of ways of assesssment. While the authors already easily offer their explanation given the lack of objective measures for sialorrhea, using instrumental swallow study evaluation would easily be the preferred way to judge swallow function and severity. Funny enough, the authors actually make the case that even this way of measuring swallow function can have high variability and based of clinical judgment (hey, when you’re right you’re right, just checkout Vose et al., 2018😉).
Second, as far as attrition and drop out rate, the authors share that this was “consistent with other behavioural treatments for such a debilitating condition,” which I don’t know about you, but is all too often and easily felt in the clinical world as well! I think this point also helps highlight the fact that this population, along with all other deteriorating illnesses, can have a much more difficult time for patients as well as their caregivers to have enough time, finances, energy, and motivation to remain engaged in any intervention, let alone for any more rigid research study. So when 7 participants originally declined to partake after being screened due to the time commitment, and one participant missed (and later remade) some sessions due to health factors, we always have to take this with a humble grain of salt.
Finally, let’s talk about what this study is and what’s it’s not…
The authors easily make it known that because the sample size is pretty small and their estimates of some of the data give a big cushion of uncertainty, more needs to be done in the future:
“To definitively examine the effect of EMST on these outcomes, an adequately powered randomised controlled trial (RCT) is needed that incorporates blinding of participants (by offering sham training to a control group).” p.5
While there were some other little pieces of the puzzle that didn’t fit as nicely and some other questions I still had such as the specific details to how IOPI was used for lip strength along with no mention of how the unsupervised sessions were confirmed for completion, this study can really make us all open our eyes into more possibilities.
So, if this study sparked your interest🤯, raise an eyebrow🤨, or got those creative clinician wheels turning🤔, this can be a perfect opportunity to really help #bridgethegap between research and clinic. Because this population desperately needs more data for more evidence, let’s put out a hand and reach out to the authors or others as we all have the same goal: to see what we can do to help our patients!🤝❤️💕💗
- “These data are encouraging and provide a strong foundation to justify a future RCT to demonstrate the effect of EMST on sialorrhea by optimising swallowing and lip closure.
- “This study provides an important first step to identifying an alternative treatment to botulinum toxin injections for sialorrhea with no side effects, high satisfaction and improved HRQoL”
- “unlike botulinum toxin injections which do not treat the cause of sialorrhea, EMST was found to result in improvements to some of the underlying factors that contribute to sialorrhea, namely reduced swallow efficiency and reduced lip closure”
- “All participants indicated that they were highly satisfied with EMST as a treatment for sialorrhea. Attendance at face-to-face treatment was high and there was an improvement in HRQoL associated with swallowing”
Article Referenced: [FREE ACCESS]
Cocks, N., Rafols, J., Embley, E., & Hill, K. (2022). Expiratory Muscle Strength Training for Drooling in Adults with Parkinson’s Disease. Dysphagia. doi: 10.1007/s00455-022-10408-6