Electrophysiological Investigations of Shape and Reproducibility of Oropharyngeal Swallowing: Interaction with Bolus Volume and Age

The 100 ml-Timed Water Swallow Test: Pilot Data from Children with No Dysphagia

Dysphagia screening tests are useful in identifying possible dysphagia for further evaluation and in supporting feeding recommendations. This study aimed to investigate swallowing parameters in children, while widening the pool of data available, using the '100 ml-Timed Water Swallow Test' (100 ml-TWST). Sixty Singaporean children aged 4 to 18 years old completed the 100 ml-TWST via a cup and a straw. Task completion, presence of cough, choke or throat clear, post-swallow voice quality, total time taken and number of swallows were observed. Subsequently, analysis of time per swallow (T/S), volume per swallow (V/S) and volume per time or swallowing capacity (V/T) were performed. Higher tendencies for coughing and task incompletion were observed in younger participants. A shorter time taken, fewer number of swallows, greater V/S and greater swallowing capacity were observed for adolescent or male participants, or via the mode of cup drinking. These could be due to oropharyngeal structural changes and swallow maturation with age, an increased capacity of oropharyngeal structures for swallowing in adolescent males, and more controlled or paced drinking from a straw. A plateau in time taken, number of swallows and swallowing capacity in adolescence were also observed, possibly indicating an emerging maturation of swallow functions during that period. Interestingly, speed of bolus movement was largely unaffected by age, gender and mode of drinking. Pilot data for children with no dysphagia have been established, while gaining insight into the swallowing parameters and maturation process in the paediatric population.

The Timed Water Swallow Test (TWST): Normative data on swallowing capacity for healthy people aged 60 years and older

PURPOSE

To provide normative data on swallowing capacity (mL/s) in people older than 60 years using the Timed Water Swallow Test (TWST), stratified by sex. Intra- and inter-rater reliability for swallowing time in TWST was further investigated.

METHOD

A total of 165 participants, aged 60 years and above, were included in the study. The time taken to consume 150 mL of tap water and the swallowing capacity (mL/s) was observed in a clinical context using the TWST. Video recordings of the performances were collected for 118 of the 165 participants for inter-rater reliability testing, of which a random set of 25 performances were assessed for intra-rater reliability. Analysis of the agreement between TWST rated by an in-person clinician and rated from a video recording was further evaluated.

RESULT

There were significant age and sex effects observed for swallowing capacity. The average reduction in swallowing capacity in the investigated age range (60-92 years) was 8.8 and 7.3 mL/s, for women and men respectively. The results showed high inter-and intra-rater reliability and agreement between the clinical assessment and the video recording.

CONCLUSION

The presented measurements indicate a clear effect of age on swallowing capacity and that women may be expected to have lower capacity scores than men when tested using TWST. The provided norms can be used as reference points in the clinical identification of people at risk of dysphagia in the older population.

Electrokinesiographic Study of Oropharyngeal Swallowing in Neurogenic Dysphagia

Electrokinesiographic study of swallowing (EKSS) can be useful for the assessment of patients with suspected or overt neurogenic dysphagia. EKSS consists of multichannel recording of the electromyographic (EMG) activity of the suprahyoid/submental muscle complex (SHEMG), the EMG activity of the cricopharyngeal muscle (CPEMG), and the laryngopharyngeal mechanogram (LPM). The LPM is an expression of the mechanical changes that the laryngopharyngeal structures undergo during the pharyngeal phase of swallowing. This method allows detailed evaluation of the magnitude, duration and temporal relations of the different events that characterize oropharyngeal swallowing, and thus in-depth exploration both of physiological deglutition mechanisms and of pathophysiological features of swallowing in neurogenic dysphagia. Furthermore, EKSS can guide dysphagia treatment strategies, allowing identification of optimal solutions for single patients. For instance, CPEMG recording can identify incomplete or absent relaxation of the upper esophageal sphincter during the pharyngeal phase of swallowing, thus suggesting a therapeutic approach based on botulinum toxin injection into the cricopharyngeal muscle. More recently, the 'shape' of SHEMG and the reproducibility of both SHEMG and LPM over repeated swallowing acts have been implemented as novel electrokinesiographic parameters. These measures could be valuable for straightforward non-invasive investigation of dysphagia severity and response to dysphagia treatment in clinical practice.

Directed Functional Coordination Analysis of Swallowing Muscles in Healthy and Dysphagic Subjects by Surface Electromyography

Swallowing is a complex sequence of highly regulated and coordinated skeletal and smooth muscle activity. Previous studies have attempted to determine the temporal relationship between the muscles to establish the activation sequence pattern, assessing functional muscle coordination with cross-correlation or coherence, which is seriously impaired by volume conduction. In the present work, we used conditional Granger causality from surface electromyography signals to analyse the directed functional coordination between different swallowing muscles in both healthy and dysphagic subjects ingesting saliva, water, and yoghurt boluses. In healthy individuals, both bilateral and ipsilateral muscles showed higher coupling strength than contralateral muscles. We also found a dominant downward direction in ipsilateral supra and infrahyoid muscles. In dysphagic subjects, we found a significantly higher right-to-left infrahyoid, right ipsilateral infra-to-suprahyoid, and left ipsilateral supra-to-infrahyoid interactions, in addition to significant differences in the left ipsilateral muscles between bolus types. Our results suggest that the functional coordination analysis of swallowing muscles contains relevant information on the swallowing process and possible dysfunctions associated with dysphagia, indicating that it could potentially be used to assess the progress of the disease or the effectiveness of rehabilitation therapies.

Conformable AlN Piezoelectric Sensors as a Non-invasive Approach for Swallowing Disorder Assessment

Deglutition disorders (dysphagia) are common symptoms of a large number of diseases and can lead to severe deterioration of the patient's quality of life. The clinical evaluation of this problem involves an invasive screening, whose results are subjective and do not provide a precise and quantitative assessment. To overcome these issues, alternative possibilities based on wearable technologies have been proposed. We explore the use of ultrathin, compliant, and flexible piezoelectric patches that are able to convert the laryngeal movement into a well-defined electrical signal, with extremely low anatomical obstruction and high strain resolution. The sensor is based on an aluminum nitride thin film, grown on a soft Kapton substrate, integrated with an electrical charge amplifier and low-power, wireless connection to a smartphone. An ad-hoc designed laryngeal motion simulator (LMS), which is able to mimic the motions of the laryngeal prominence, was used to evaluate its performances. The physiological deglutition waveforms were then extrapolated on a healthy volunteer and compared with the sEMG (surface electromyography) of the submental muscles. Finally, different tests were conducted to assess the ability of the sensor to provide clinically relevant information. The reliability of these features permits an unbiased evaluation of the swallowing ability, paving the way to the creation of a system that is able to provide a point-of-care automatic, unobtrusive, and real-time extrapolation of the patient's swallowing quality even during normal behavior.

Electromyographic activation patterns during swallowing in older adults

Age-related weakness due to atrophy and fatty infiltration in oropharyngeal muscles may be related to dysphagia in older adults. However, little is known about changes in the oropharyngeal muscle activation pattern in older adults. This was a prospective and experimental study. Forty healthy participants (20 older [> 60 years] and 20 young [< 60 years] adults) were enrolled. Six channel surface electrodes were placed over the bilateral suprahyoid (SH), bilateral retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles. Electromyography signals were then recorded twice for each patient during swallowing of 2 cc of water, 5 cc of water, and 5 cc of a highly viscous fluid. Latency, duration, and peak amplitude were measured. The activation patterns were the same, in the order of SH, TH, and StH, in both groups. The muscle activation patterns were classified as type I and II; the type I pattern was characterized by a monophasic shape, and the type II comprised a pre-reflex phase and a main phase. The oropharyngeal muscles and SH muscles were found to develop a pre-reflex phase specifically with increasing volume and viscosity of the swallowed fluid. Type I showed a different response to the highly viscous fluid in the older group compared to that in the younger group. However, type II showed concordant changes in the groups. Therefore, healthy older people were found to compensate for swallowing with a pre-reflex phase of muscle activation in response to increased liquid volume and viscosity, to adjust for age-related muscle weakness.

Reproducibility and reaction time of swallowing as markers of dysphagia in parkinsonian syndromes

OBJECTIVE

To investigate reproducibility and reaction time of oropharyngeal swallowing in patients with Parkinson's disease (PD) and atypical parkinsonisms (APs).

METHODS

We enrolled 19 patients with PD, 30 with APs, and 20 healthy subjects. Presence and severity of dysphagia were assessed with clinical and fiberoptic endoscopic evaluations of swallowing. Reproducibility of the oral and pharyngeal phases of swallowing were respectively assessed by calculating the 'similarity index' of the electromyography activity of the submental/suprahyoid muscles and of the laryngeal-pharyngeal mechanogram during consecutive swallows. These were performed both 'on command' and spontaneously. The swallowing reaction time was also recorded.

RESULTS

Reproducibility of the oral phase of swallowing was reduced in patients with dysphagia, mainly when swallowing 'on command'. Swallowing reaction time was prolonged in dysphagic patients. These electrophysiological parameters did not vary among different parkinsonian syndromes and correlated with dysphagia severity.

CONCLUSIONS

Increased variability of oral swallowing automatisms and abnormal sensorimotor integration may be of relevance for the pathophysiology of dysphagia in parkinsonian syndromes.

SIGNIFICANCE

The electrophysiological assessment represents a valuable tool to investigate swallowing alterations in parkinsonian syndromes. It may also provide useful insights into clinical severity and pathophysiology of dysphagia, giving clues for the choice of the best therapeutic approach.

Anodal transcranial direct current stimulation and intermittent theta-burst stimulation improve deglutition and swallowing reproducibility in elderly patients with dysphagia

BACKGROUND

Dysphagia in the elderly, known as presbydysphagia, has become a relevant public health problem in several countries. Swallowing disorders may be a consequence of different neurological disorders (secondary presbydysphagia) or the expression of the aging process itself (primary presbydysphagia). We aimed to test the therapeutic potential of two different non-invasive brain stimulation (NIBS) techniques in subjects with primary or secondary presbydysphagia.

METHODS

A blinded randomized controlled trial with crossover design was carried out in 42 patients, randomly assigned to anodal transcranial direct current stimulation (tDCS) or intermittent theta-burst stimulation (TBS) group. Both tDCS and TBS were applied for 5 consecutive days over the right swallowing motor cortex. The swallowing function was assessed before and 1 and 3 months after the stimulation using the Dysphagia Outcome and Severity Scale (DOSS), scored based on clinical assessment and fiberoptic endoscopic evaluation of swallowing. An electrophysiological method was also applied to evaluate changes in the reproducibility of the swallowing behavior.

KEY RESULTS

Both real tDCS and TBS had beneficial effects on the swallowing function in patients with primary and secondary presbydysphagia. Anodal tDCS resulted in an improvement of 0.5 points in DOSS at 1-month follow-up (P = .014), whereas intermittent TBS induced an increase of 0.7 and 0.6 points at 1- and 3-month follow-up evaluations, respectively (P = .0001 and P = .005, respectively). Reproducibility of both the oral and pharyngeal phases of swallowing significantly increased at 1-month follow-up.

CONCLUSIONS AND INFERENCES

Our results suggest that non-invasive cortical stimulation may be useful for dysphagia recovery in elderly patients.

Swallowing Pressure Variability as a Function of Pharyngeal Region, Bolus Volume, Age, and Sex

OBJECTIVES

Within-individual movement variability occurs in most motor domains. However, it is unknown how pharyngeal swallowing pressure varies in healthy individuals. We hypothesized that: 1) variability would differ among pharyngeal regions; 2) variability would decrease with increased bolus volume; 3) variability would increase with age; and 4) there would be no sex differences.

STUDY DESIGN

Case series.

METHODS

We used pharyngeal high-resolution manometry to measure swallowing pressure in the following regions: velopharynx, tongue base, hypopharynx, and upper esophageal sphincter. Data were collected from 97 healthy adults (41 male) aged 21 to 89 years during thin liquid swallows: 2 mL, 10 mL, and participant-selected comfortable volume. Pressure variability was measured using coefficient of variation. Repeated measures analysis of variance was used to assess impacts of region, bolus volume, age, and sex on pressure variability.

RESULTS

There was a significant region × volume interaction (P < .001) and significant main effect of age (P = .005). Pressures in the hypopharynx region were more variable than all other regions (P ≤ .028), and pressures in the tongue base region were less variable than all other regions (P ≤ .002) except at 2 mL volumes (P = .065). Swallowing pressure variability was significantly different in the velopharynx and upper esophageal sphincter regions, with comfortable volume and 2 mL swallows having greater variability than 10 mL swallows (P ≤ .026). Pressure variability significantly increased with increasing age (P = .002). There were no effects of sex on pressure variability (P ≥ .15).

CONCLUSION

Pharyngeal swallowing pressure variability differs according pharyngeal region, volume, and age but not sex. Abnormal swallowing pressure variability may reflect deviations in motor control in persons with swallowing impairment, and results from this study can be used as normative data for future investigations evaluating swallowing pressure generation.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E52-E58, 2021.

Effects of the head lift exercise and neuromuscular electrical stimulation on swallowing muscles activity in healthy older adults: a randomized pilot study

PURPOSE

Swallowing physiology exhibits several changes in advanced ages. The present study aimed to investigate and compare effects of a period of the head lift exercise (HLE) and neuromuscular electrical stimulation (NMES) on swallowing muscles activity in healthy elderly.

PATIENTS AND METHODS

A total of 23 older adults were randomized to either the HLE or NMES group for ten therapy sessions. They received pre- and post-therapy surface electromyography (sEMG) during water swallowing.

RESULTS

For the HLE group, duration of suprahyoid muscles activity was significantly reduced at post-intervention compared to pre-intervention (p=0.036). Moreover after treatments, duration and latency between onset and peak amplitude of suprahyoid muscles activity was significantly shorter in the HLE group compare to the NMES group (respectively, p=0.007 and p=0.003).

CONCLUSION

Our findings suggest that the HLE, against the NMES, may be effective in reducing some aging effects on the suprahyoid muscles activity, especially in elders who demonstrate prolonged duration and latency between onset and peak of the suprahyoid muscles activity during swallowing.

Identification of swallowing disorders in early and mid-stage Parkinson's disease using pattern recognition of pharyngeal high-resolution manometry data

BACKGROUND

Parkinson's disease (PD) can cause severe dysphagia, especially later in disease progression. Early identification of swallowing dysfunction may lead to earlier intervention. Pharyngeal high-resolution manometry (HRM) provides complementary information to videofluoroscopy, with advantages of being quantitative and objective. Artificial neural network (ANN) classification can examine non-linear relationships among multiple variables with relatively low bias. We evaluated if ANN techniques could differentiate between patients with PD and healthy controls.

METHODS

Simultaneous videofluoroscopy and pharyngeal HRM were performed on 31 patients with early to mid-stage PD and 31 age- and sex-matched controls during thin-liquid swallows of 2 cc, 10 cc and comfortable sip volume. We performed multilayer-perceptron analyses on only videofluoroscopic data, only HRM data or a combination of the two. We also evaluated variability-based parameters, representing variability in manometric parameters across multiple swallows. We hypothesized that patients with PD and controls would be classified with at least 80% accuracy, and that combined videofluoroscopic and HRM data would classify participants better than either alone.

KEY RESULTS

Classification rates were highest with all parameters considered. Maximum classification rate was 82.3 ± 5.2%, recorded for 2 cc swallows. Inclusion of variability-based parameters improved classification rates. Classification rates using only manometric parameters were similar to those using all parameters, and rates were substantially lower for the comfortable sip volumes.

CONCLUSIONS & INFERENCES

Results from these classifications highlight the differences between swallowing function in patients with early and mid-stage PD and healthy controls. Early identification of swallowing dysfunction is key to developing preventative swallowing treatments for those with PD.

Dental status, oral prosthesis and chewing ability in an adult and elderly population in southern Brazil

OBJECTIVE

The objective of this study was to explore the factors associated with inadequate chewing in an adult and elderly population of a city in the southern region of Brazil.

METHODS

This was a cross-sectional study based on a population home-based inquiry (DCH-POP) in southern Brazil. Individuals were interviewed by trained interviewers to create a standardized procedure. In a pilot study, the Questionnaire of Human Communication Disorders (DCH-POP) was created and validated to identify self-reported speech and language, swallowing and hearing disorders. The outcome was dichotomized into either having adequate chewing or not, as assessed by a series of questions about chewing ability. Analyses of absolute and relative frequencies were measured according to the studied variables. A Poisson regression was applied at a significance level of 5%.

RESULTS

A total of 1,246 people were interviewed. Inadequate chewing was found in 52 (5.6%) individuals, with a higher prevalence in the elderly (11.8%) than in adults (5.2%). In the final model, the following factors were associated with inadequate chewing: being 61 years of age or older (prevalence ratio or PR=9.03; 95% CI: 1.20-67.91), loss of teeth and use of unadjusted prosthesis (PR=3.50; 95% CI: 1.54-7.95), preference for foods of soft consistency (PR=9.34; 95% CI:4.66-8.70) and difficulty in nasal breathing (PR=2.82; 95% CI: 1.31-6.06).

CONCLUSION

Age, oral health status through dental prosthesis, preference for foods of soft consistency and difficulty breathing through the nose were factors associated with chewing inability in adults and the elderly.

The importance of the reproducibility of oropharyngeal swallowing in amyotrophic lateral sclerosis. An electrophysiological study

OBJECTIVE

To investigate electrophysiologically the reproducibility of oropharyngeal swallowing in patients with ALS.

METHODS

We enrolled 26 ALS patients, both with and without clinical signs of dysphagia, and 30 age-matched controls. The reproducibility of the electrophysiological signals related to the oral phase (electromyographic activity of the submental/suprahyoid muscles) and the pharyngeal phase (laryngeal-pharyngeal mechanogram) of swallowing across repeated swallows was assessed. To do this we computed two similarity indexes (SI) by using previously described mathematical algorithms.

RESULTS

The reproducibility of oropharyngeal swallowing was significantly reduced both in patients with and in those without clinical signs of dysphagia, with more marked alterations being detected in the dysphagic group. The SI of both phases of swallowing, oral and pharyngeal, correlated significantly with dysphagia severity and disease severity.

CONCLUSIONS

In ALS different pathophysiological mechanisms can alter the stereotyped motor behaviors underlying normal swallowing, thus reducing the reproducibility of the swallowing act. A decrease in swallowing reproducibility could be a preclinical sign of dysphagia and, beyond a certain threshold, a pathological hallmark of oropharyngeal dysphagia.

SIGNIFICANCE

Electrophysiological assessment is a simple and useful tool for the early detection of swallowing abnormalities, and for the management of overt dysphagia in ALS.