Why do we do what we do?🤔
Why does the sun set in the west?
Or the sky look blue?
So many philosophical questions that might have pretty complicated and lengthy answers🤷♀️. Luckily, the questions that surround the use of compensatory strategies can be answered a lot quicker with this relevant article by an SLP Great🤩, in a Short ‘n Sweet way!!
The article easily breaks up the compensations we typically implement in our clinical practices into 3 groups, then gives us the history behind these as well as the limitations and other things to consider (ya know, since our profession can’t have the same reputation as a Snuggie😉).
Bolus Variables – Volume/Viscosity
Just in case you’ve been looking for a solid conversation-starter with other SLPs (or anybody), these have actually been looked at since the 1980s!😉🤩
So what do these change when it comes to swallowing?
- Increased peak lingual force
- Shorter duration of tongue base contact to posterior pharyngeal wall
- sEMG evidence show increased muscle activity within submental and laryngeal musculature
- Earlier onset and longer anterior/superior hyo-laryngeal movement
- Earlier and longer laryngeal vestibule closure as volume increases
- Later epiglottic inversion
- Increased pharyngeal transit time/prolonged duration of pharyngeal shortening
- NO change in pharyngeal pressures
- Increased width opening within upper esophageal sphincter (UES/PES)
- Increased duration and pressure on the bolus through UES
- Head of the bolus shifts to deeper in pharynx as UES opens
- Increase in lingual pulsive force, tongue pressure to the palate, and tongue clearing pressure
- EMG studies showing “systematic increase in muscle activity” in submental musculature (including anterior belly of digastric, mylohyoid, geniohyoid)
- Increased oral transit duration and total swallow duration
- Inconsistent findings for increases in pharyngeal contractive pressures
- “systematic increases” in hyo-laryngeal muscular activity (sternohyoid/thyroid musculature)
- Increased amplitude of vertical and anterior hyoid/laryngeal motion
- Longer laryngeal vestibule closure
- Increased pharyngeal transit duration
- Increased intrabolus pressure at UES
- Increased time until UES opening
- Increased width and duration of UES opening
The article also gives a *quite* clear (almost painfully clear) reminder, that Thicker≠Better:
“A thicker bolus was believed to result in improved swallow safety..However, a randomized clinical trial examining three interventions, including chin tuck plus thin liquids, nectar-thick, versus honey-thick liquids in dysphagic Parkinson’s and dementia patients revealed that patients randomized to honey-thick liquids had the highest incidence of aspiration pneumonia“
“Thus, thicker boluses should be examined with instrumental assessment and should be used judiciously.” p.3
“Postures have been described as altering bolus flow through the oral cavity and pharynx” p.3
- Useful for a delayed pharyngeal motor response (which may result in aspiration before swallow triggers)
- Widens vallecular space which allows more area for liquids/foods to catch during a delay
- Narrows airway entrance, resulting in arytenoids approximating epiglottic base more closely (helpful in reduced airway closure)
- Increased duration of laryngeal vestibule closure (compared to neutral position)
- Can improve bolus clearance at base of tongue, valleculae, and reduced residue at upper pharyngeal wall
- No changes shown with low/high-resolution manometry for pharyngeal pressures
- Increased duration pharyngeal contractions, but no change in actual pharyngeal pressures with low/high-resolution manometry
- Increased duration in drop of UES pressure for acceptance of bolus into sphincter
“Chin tuck with thin liquids has been found to be equally effective as the use of nectar-thick liquids in the prevention of aspiration pneumonia in Parkinson’s and dementia patients” p.3
That last part is super great especially for anyone who does not think mildly thick liquids are satisfying. On the flip side, I feel one can’t help but wonder about the generalizability of this for these specific populations (I am sure the actual studies make specific distinctionsfor mild vs severe conditions etc., so I will have to read further obviously). But, given the options, I guess that’s what clinicians and their patients have to think about!
Head Back Posture:
- Useful for difficulty with anterior-posterior bolus propulsion in oral cavity by using gravity
- Helpful for post-surgical intervention oral cancer patients or impaired tongue mobility for dysarthric patients
Head Rotation Posture:
- Useful for unilateral pharyngeal weakness
- Reduces bolus clearance through pharynx and residue particularly on damaged/weak side
- Redirects bolus towards unimpaired side
- Reduces UES resting pressure, widens UES opening to allow more bolus to flow through, and increases UES duration
- Evidence from case study involving dysphagia from brain stem stroke, and objective measurements within healthy subjects
“More recently, the combination of chin tuck+head rotation has been found to result in significant reduction in residue for thin and nectar-thick liquids as compared to head neutral, as measured with the Normalized Residue Ratio Scale” p.3
- Useful when pharyngeal clearance is reduced by “allowing residue to remain on lateral pharyngeal wall after the swallow” with additional dry swallows to further clear residue versus entering the airway as in upright posture
- Evidence for one case-study for TBI dysphagic patient
Head Tilt Posture:
- Useful for unilateral oral and/or pharyngeal weakness to allow bolus to clear oral/pharyngeal cavity on stronger side
- Useful for patients post hemiglossectomy or dysarthria with hemiparesis
- No generalize-able study for large population of dysphagia patients
- Single study with high-resolution manometry demonstrating lower maximum UES pressures compared to head neutral
So, there is obvious mention of Tactile-Thermal Stimulation (TTS) in this category, which does have evidence that supports short-term effects on the pharyngeal motor response regarding a delayed pharyngeal swallow, particularly with stroke patients. However, the ability to not only generalize this across populations has NOT been found, and the long-term actual treatment impact of this has still not yet been established (If I’m overlooking something please let me know though!😉).
For more specifically cold temperature alone, some studies have shown shortening of oral phase in dysphagic patients and possibly shorter swallow latency in healthy adults; however none of these studies were randomized in any way🤨. .
In any case, anybody ever wonder when all our ice-cold laryngeal mirrors will be presented on Antique RoadShow?😅
Even Transcranial Magnetic Stimulation has inconsistent findings, with some showing “increase in cortical excitability in health and stroke patients, and also found to inhibit the swallow response,” and others have shown negative effects (causing the hyo-laryngeal complex to depress versus elevating, [see Ludlow & Humbert et al. (2007)].
“A  meta-analysis found a small statistically significant improvement in clinical swallow performance in a group of adult dysphagic patients who underwent electrical stimulation therapy; however, there were some reported limitations to this study . A more recent systematic review concluded that evidence of efficacy is lacking at this time” p.8
As far as taste goes, there’s still some mixed reviews (including SLP R&R’s previous post–Sweet until sour?? Taking a bite out of taste manipulation). But, while there’s been NO evidence for changes in lingual motion for sour bolus (compared to water) (Steele et al., 2012), a few different studies have shown:
- Reduced laryngeal penetration/aspiration plus more dry swallows four sour bolus with neurologically impaired dysphagic patients
- Improved speed of pharyngeal transit time for treated head & neck cancer patients
- Increased cortical excitability with citric acid liquid in healthy adults
Keep taking this all with just a grain of salt🧂? Or a bubble of carbonation🍾:
“More recent studies have provided additional support for the use of carbonation, with the increased magnitude and duration of linguapalatal swallow pressures, submental sEMG activity, and the increased bolus velocity through the pharynx. In addition, increased percent of successfully timed swallows and increased corticobulbar excitability with a carbonated bolus versus still water have been observed in healthy subjects.” p.5
And then there all those “common sense” strategies we might try or recommend like double (dry) swallowing, liquid assist or liquid washes, eating slowly, or having extra time to swallow to further improve swallow efficiency.
“Compensatory strategies have also been found to result in reduced risk of medical sequelae such as aspiration pneumonia and can result in improved nutritional status” p.5
At the end of the day (or really, at the beginning), all these strategies not only are NOT a one-size-fits-all, but also need to be analyzed objectively from direct observations from swallow study instrumentation, so we know we’re not doing more damage than good!🤓
Before you go, I DEFINITELY recommend checkout out the References from the original article, and also remember any more recent studies that may have the most current findings to any of the strategies!😀
(Also I swear I tried my best to make this review actually shorter guys😅, but when there are just so many goodies to highlight it’s not easy🤪!!)
Lazarus, C. (2017). History of the Use and Impact of Compensatory Strategies in Management of Swallowing Disorders. Dysphagia, 32(1), 3-10. doi: 10.1007/s00455-016-9779-6