Title: Effects of Mendelsohn Maneuver on Measures of Swallowing Duration Post-Stroke
Author: McCullough, G., Kamarunas, E., Mann, G., Schmidley, J., Robbins, J., Crary, M.,
Journal: Topics in Stroke Rehabilitation
Year of Publication: 2012
Design Type: exploratory pilot study
Purpose: “The purpose of this investigation was to determine if any lasting changes would occur in swallowing physiology as a result of intensive exercise using the Mendelsohn maneuver.”
Population: 18 adults post CVA with pharyngeal dysphagia
Inclusion criteria: adults >21 years old with previous CVA (between 6 weeks-22 months post); dysphagia diagnosis with apparent pharyngeal impairments (i.e. reduced hyolaryngeal elevation, UES opening, residue); restricted diet and/or alternative feeding (tube); 75 or higher on the Modified Mini-Mental State Examination
Exclusion criteria: individuals with normal or absent swallow; tracheostomy/structural abnormalities; history of dysphagia before CVA; progressive neurological diseases; difficulty understanding/completing therapeutic instructions
Look, we’re all different. You say “Mendelsohn Maneuver,” I might say “voluntary prolongation of hyolaryngeal elevation at the peak of the swallow” (just kidding). We all have our strengths and weaknesses. Mine tend to be clothes, pizza, and moderate doses of sarcasm. Math, technology, and singing on the other hand, definitely in the weakness column. Now, can I just avoid my weaknesses? I wish! (I mean, I can’t NOT sing in the shower/car). So I’ll be bravely honest that the Mendelsohn has not always been my first thought in mind for swallow maneuvers/exercises for a large majority of patients for multiple reasons:
- not always appropriate for my more cognitively-impaired patients (which can sometimes be very prominent in caseloads)
- difficulty with biofeedback and accuracy (Enter: sEMG thank you very much)
- can be difficult to explain and model (again, sEMG can be a saving grace..still waiting to get my hands on one of these bad boys…discount/sponsorship always welcomed 😉 )
This is not to say it’s never used, just that after critical thinking and being mindful of the ‘patient’ part of the EBP, the reasons above typically give rationales to employ other variations of exercises and techniques (hence individualized plan of care). I remember reading the directions for Mendelsohn in Logemann’s original textbook as a student, feeling my own “Adam’s apple” rise and lower, seeing how long I could even hold it. For a beginner clinician (and somewhat thereafter), it was quite confusing and vague, but eventually I got the hang of it (or learned to “let it hang”?).
Here’s where this article hooked me. Did you know the Mendelsohn hadn’t been looked at or “tested” by itself to see if it helped swallow function? It also hadn’t been concluded what, if any, specific swallow functions were impacted. It also was not known if Mendelsohn had any long-term effects over time.
“Early reports on the Mendelsohn maneuver suggested use of the maneuver increases laryngeal elevation and maximal hyoid superior displacement and provides an immediate effect in prolonging the duration of opening of the upper esophageal sphincter (UES) but not the diameter.”
“Since the initial reports, more data have emerged supporting the physiologic effects of the Mendelsohn maneuver on the act of swallowing, but most papers consider only the immediate effects of the maneuver on small numbers of normal participants or patients.” p.1
Why would this be important? If some research had already shown benefits, why should we care what specifically made a difference and what that difference was? Well, first, that’s what researchers do. They look to answer these specific, detailed, pieced-apart questions to help us clinicians know for sure what we are doing in therapy is beneficial or not.
“the specific physiologic effects of the Mendelsohn maneuver on patients with dysphagia cannot be determined without investigation of the maneuver in isolation.” p.1
“These studies have clearly demonstrated that dysphagia rehabilitation is possible in certain patients post-stroke; but without specifically examining the use of individual exercises in isolation, the contribution of any particular exercise cannot be clearly defined.” p.2
“In other words, while the Mendelsohn maneuver appears to have an immediate effect on hyolaryngeal movement and duration of UES opening, no data exist to define what, if any, lasting effect use of the Mendelsohn maneuver over time may have on the physiology of swallowing when the Mendelsohn maneuver is no longer employed.” p.2
So while obviously there have been other studies looking at these things since 2012, let’s go back in time for a bit to understand how we got where we are today…..
My critical eye had me read through the inclusion/exclusion criteria multiple times to really understand just who they were looking at for the study. Deep down I wished there was some mention if any subjects had any previous swallow therapy, which could obviously make a difference if one patient had been practicing in a hospital with a therapist beforehand, while another at home had not done been doing any “pre-treatment” at all.
Something else that caught my eye was a bit of a big range across the subjects for time post stroke, making me consider spontaneous recovery (typically seen earlier post CVA). Luckily, the authors do mention this limitation and address that they were primarily concerned with “post-acute rehabilitation but not necessarily chronic population.” For the most part, they took anyone and everyone who had a stroke, had specific swallow impairments, and could/would participate until they felt like they had a good enough number of participants to have a powerful study.
They then randomly split them into 2 groups (remember, random = GOOD study strength/power!)
“Each remaining individual was randomized, via pre-study blinded number drawing, into one of two groups: Group A received two weeks of treatment followed by two weeks of no-treatment (BBAA) and Group B received two weeks of no treatment followed by two weeks of treatment (AABB).” p.3
The A-B-A took me back to my Research Methods graduate course where B=treatment, and A=placebo/no treatment. To break this down further, they are basically seeing if 2 weeks of treatment are beneficial to have lasting effects after treatment, or if there is only immediate effects with the treatment.
No matter what group, at the end of every week the participants completed a repeatable VFSS protocol (3 mL thin liquids, 3 mL puree) in order to see changes as treatment/time progressed. Now, within the VFSS the participants “were instructed to hold the bolus until they were asked to swallow and to use subsequent swallows, if needed, to clear the bolus.” Given what we now know in 2019 about cued versus non-cued swallow (e.g. timing and bolus flow), I’m not sure if that means an actual cued swallow or the “okay, now you can swallow when you’re ready” deal we might typically do in fluoro.
Because I easily get bored without something to visually hold my attention, here’s the image that popped up when trying to wrap my head around all this (for future researchers, I definitely appreciate when this little step is already done for me 😀 )……
Before planning a parade for this design, a researcher friend helped me realize that while the blinding+randomization in this “pre-test/post-test” design is a good start, it really isn’t the top tamale of design because in order to really support a claim of causality (aka “Mendelsohn did it!”), having multiple phases of this (ABABA) are really needed to make this an even stronger argument. Food for thought, no?🤔
Here’s also a quick list of what the authors were specifically looking at after each VFSS, along with some other general measures°. (see full article, Table 2 for full list of measures):
- duration of opening of upper esophageal sphincter (DOUESO)
- duration of hyoid maximum anterior excursion (DOHMAE)
- duration of hyoid maximum elevation (DOHME)
- Penetration-Aspiration Scale (PAS)
- Dysphagia Outcome and Severity Scale (DOSS)
Recordings were analyzed with accepted standard frame-by-frame review after each study either by DVD or VHS (Video Home System📼📼)–ya know, those dusty, black rectangular blocks some clinicians’ parents might still have lying around 😉 (it’s what we had at the time; and may not be arguably as good in quality, but don’t judge a tape by its cover😋).
What did the clinicians do for the Mendelsohn? More importantly, what did the patients do for the Mendelsohn?
There was some training time for Mendelson with sEMG for baseline/feedback with 30-40 swallow targets during the 2 weeks of treatment (both groups), for 2 sessions a day with a 2-3 hour break in between (sessions lasting 45-60 minutes) usually by the same investigator.
The authors briefly mention a study clinician assisting once “participants were well-trained with the treatment procotol,” however, my curiosity meter peaked to know just what the “mastery” level was and how they determined this? Luckily they do state what a successful Mendelsohn looked like for all you curious cats:
“A successful Mendelsohn swallow meant the participant was able to swallow and sustain laryngeal elevation for approximately 2 seconds or greater.” p.5
A good quick intro on sEMG is also provided which was a nice refresher and also emphasized the importance of recruitment of muscles in order to have an effect (Check it out here).
Okay, so we all know how to do a Mendelsohn (hopfeully)………….
With sufficient blinding, randomization, and high post-VFSS measure inter-judge reliability, here’s what the authors found:
“Results after two weeks of treatment were better than results after one week of treatment,” p.6
Which, we pretty much all know that more (good) treatment typically > less/no treatment…..
“and results after two weeks of no-treatment were worse than results after one week of no-treatment with the exception of DOUESO, which made a non-significant improvement in respective no-treatment weeks.”p.6
Again, pretty “SLP-common sense” there…
Results did show that how long the hyoid moved anteriorly and superiorly were significant! Meaning, the Mendelsohn DID have a treatment effect in the study by improving how long the hyoid stayed up and forward during the swallow!
In other news,
“Results for pharyngeal response duration (PRD), which measures the duration of hyoid movement from start to finish, trended with DOHME and DOHMAE, getting worse during periods of no-treatment and better during periods of treatment. No other measures trended this direction.” p.6
And that’s not all folks,
“Duration of upper esophageal sphincter opening (DOUESO) also improved during treatment weeks compared to no-treatment weeks, though results were not statistically significant.” p.6
If you’re sitting there brain-a-buzzing thinking, Why wouldn’t the other measures be changed? Why wouldn’t timing improvements in hyoid movement improve a bunch of other physiological swallow components??
Well, because it’s not always about the hyoid! That, and the fact that swallowing is a complex, inter-related system.
“Measures of bolus flow, however, may be affected by factors other than hyoid movement—i.e., pharyngeal muscle strength, epiglottic tilt and seal, or tongue base strength.” p.6
What this study is and is not:
If you take a look at the participants they had, it’s pretty obvious how many results we can’t generalize to the whole post-stroke population. Also, even though the study gave some evidence essentially saying “more Mendelsohns are better than less or none,” and “2 weeks of treatment may not be enough” and really “the effects of the exercise on swallowing physiology should be examined over longer periods of time more than one month. Outcome measures at 6 and 12 month should be examined.”
The study was also an exploratory one, which is just the beginning of having us starting to think about something and how it works, and a long way to go for having us definitively and confidently state this.
“The fundamental purpose of Phase I research is selecting a therapeutic effect, identifying it if present, and estimating its magnitude” p.6
And there went my curiosity meter going off again🎚📶…
Doesn’t feedback have a positive effect on swallow exercise execution and accuracy? [See Azola et al. article] So, since we know this, can the results really be solely based on Mendelsohn maneuver? This is another important idea to keep in mind for clinicians who are literally just looking for answers (don’t worry, I am one of these too!😊)—we can’t just jump to the conclusions! Because multiple interventions are being implemented (even though the article is explaining how they are only focused on the Mendelsohn), we really have to stop and consider if this is actually construct validity (aka testing what it says it’s testing). For example, because these 2 things are not being evaluated separately, we really cannot determine whether the effects are the result of Mendelsohn or visual feedback. To test this, us curious cats need to keep our critical thinking caps from collecting dust:
- The optimist may say that “the Mendelsohn maneuver can improve DOHMAE and DOHME”
- The pessimist might say “we don’t know because we can’t separate the effects of sEMG and the maneuver”
- While the realist would state “the Mendelsohn maneuver with sEMG biofeedback can be effective”
How can you use this article?!?
Are you more willing to use “The Mendelsohn” with more patients when appropriate?
What other exercises/techniques are you curious about the “evidence” ?!
Have you observed any other effects or the “magic” dosage? (If so, please share!)
And what are some tips/tricks you’ve developed to help patients understand and execute this manuever correctly?!?
I’m sure there’s bunches more research on this topic (I believe some coming out soon?), but at least now we can all let our hyoids sleep more peacefully finally knowing what we are doing in therapy matters, and although we could use more, there’s at least some evidence to prove it. 😉
“Our exploratory study indicates the Mendelsohn maneuver, used as a rehabilitation exercise, can improve the duration of hyoid maximum anterior and superior movement and impact the duration of UES opening.” p.6
- “Data show that DOHME (hyoid elevation) and DOHMAE (hyoid anterior excursion) significantly improved (were prolonged) during VFSS evaluation of swallowing after treatment weeks and did not improve after no-treatment weeks.”
- “Duration of upper esophageal sphincter opening (DOUESO) also improved during treatment weeks compared to no-treatment weeks, though results were not statistically significant. With a larger sample, it is very possible this trend would continue and become significant.”
- “Prior studies employing the Mendelsohn maneuver have reported success with sessions once or twice daily over a 1 to 2 week period providing intense neuromuscular rehabilitation in an effort to improve both the strength and coordination of the swallow.”
- “swallowing post-stroke can become not only weak but discoordinated, and more coordinated “patterns” of swallowing activity occur with more intensive treatment.”
- “Measures of bolus flow, however, may be affected by factors other than hyoid movement—i.e., pharyngeal muscle strength, epiglottic tilt and seal, or tongue base strength.”
Article referenced: [FREE ACCESS]
McCullough, G. H., Kamarunas, E., Mann, G. C., Schmidley, J. W., Robbins, J. A., & Crary, M. A. (2012). Effects of Mendelsohn maneuver on measures of swallowing duration post stroke. Topics in stroke rehabilitation, 19(3), 234–243. doi:10.1310/tsr1903-234
Timing differences between cued and noncued swallows in healthy young adults. https://www.ncbi.nlm.nih.gov/pubmed/23456325
Effects of Verbal Cue on Bolus Flow During Swallowing https://pubs.asha.org/doi/pdf/10.1044/1058-0360%282007/018%29
Kinematic visual biofeedback improves accuracy of learning a swallowing maneuver and accuracy of clinician cues during training https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5303684/pdf/nihms819712.pdf