Spatiotemporal characteristics of the pharyngeal event-related potential in healthy subjects and older patients with oropharyngeal dysfunction

Swallowing and Aspiration: How to Evaluate and Treat Swallowing Disorders Associated with Aspiration Pneumonia in Older Persons

Aspiration pneumonia (AP) is the most severe complication of oropharyngeal dysphagia (OD). It is highly underdiagnosed and undertreated among older patients hospitalized with community-acquired pneumonia (CAP). Our aim is to review the state of the art in the diagnosis and treatment of swallowing disorders associated with AP. We performed a narrative review, including our experience with prior studies at Hospital de Mataró, on the diagnosis and treatment of AP. AP refers to pneumonia occurring in patients with swallowing disorders, frequently coinciding with poor oral health and vulnerability. Its main risk factors include oropharyngeal aspiration, impaired health status, malnutrition, frailty, immune dysfunction, and oral colonization by respiratory pathogens. Incidence is estimated at between 5 and 15% of cases of CAP, but it is highly underdiagnosed. Diagnostic criteria for AP have not been standardized but should include its main pathophysiological element, oropharyngeal aspiration. Recently, a clinical algorithm was proposed, based on the recommendations of the Japanese Respiratory Society, that includes aspiration risk factors and clinical evaluation of OD. To facilitate the task for health care professionals, new artificial intelligence (AI)-based screening tools for OD combined with validated clinical methods such as the volume-viscosity swallowing test (V-VST) for the detection of AP are being validated. Prevention and treatment of AP require multimodal interventions aimed to cover the main risk factors: textural adaptation of fluids and diets to avoid oropharyngeal aspiration; nutritional support to avoid malnutrition; and oral hygiene to reduce oral bacterial load. The diagnosis of AP must be based on standardized criteria providing evidence on the main etiological factor, oropharyngeal aspiration. Clinical algorithms are valid in the diagnosis of AP and the identification of its main risk factors. Combination of AI-based tools with V-VST can lead to massive screening of OD and save resources and improve efficiency in the detection of AP.

Neurophysiological characterization of oropharyngeal dysphagia in older patients

OBJECTIVE

To characterize swallowing biomechanics and neurophysiology in older patients with oropharyngeal dysphagia (OD).

METHODS

Observational study in 12 young healthy volunteers (HV), 9 older HV (OHV) and 12 older patients with OD with no previous diseases causing OD (OOD). Swallowing biomechanics were measured by videofluoroscopy, neurophysiology with pharyngeal sensory (pSEP) and motor evoked-potentials (pMEP) to intrapharyngeal electrical and transcranial magnetic stimulation (TMS), respectively, and salivary neuropeptides with enzyme-linked immunosorbent assay (ELISA).

RESULTS

83.3% of OOD patients had unsafe swallows (Penetration-Aspiration scale = 4.3 ± 2.1; p < 0.0001) with delayed time to laryngeal vestibule closure (362.5 ± 73.3 ms; p < 0.0001) compared to both HV groups. OOD patients had: (a) higher pharyngeal sensory threshold (p = 0.009) and delayed pSEP P1 and N2 latencies (p < 0.05 vs HV) to electrical stimulus; and (b) higher pharyngeal motor thresholds to TMS in both hemispheres (p < 0.05) and delayed pMEPs latencies (right, p < 0.0001 HV vs OHV/OOD; left, p < 0.0001 HV vs OHV/OOD).

CONCLUSIONS

OOD patients have unsafe swallow and delayed swallowing biomechanics, pharyngeal hypoesthesia with disrupted conduction of pharyngeal sensory inputs, and reduced excitability and delayed cortical motor response.

SIGNIFICANCE

These findings suggest new elements in the pathophysiology of aging-associated OD and herald new and more specific neurorehabilitation treatments for these patients.

Microbiological Profile of Patients with Aspiration Pneumonia Identified by Combined Detection Methods

Purpose

Aspiration pneumonia (AP) challenges public health globally. The primary aim of this study was to ascertain the microbiological profile characteristics of patients with AP evaluated by combined detection methods, including conventional microbiological tests (CMTs), chips for complicated infection detection (CCID), and metagenomic next-generation sequencing (mNGS).

Patients and Methods

From June 2021 to March 2022, a total of thirty-nine patients with AP or community-acquired pneumonia with aspiration risk factors (AspRF-CAP) from 3 hospitals were included. Respiratory specimens, including bronchoalveolar lavage fluid (BALF), sputum, and tracheal aspirate, were collected for microorganism detection.

Results

Patients with AP were more inclined to be older, to have a shorter duration from illness onset to admission, to have a higher prevalence of different underlying diseases, particularly diabetes mellitus, chronic heart disease, and cerebrovascular disease, and to have a higher CURB-65 score (all P < 0.05). A total of 213 and 31 strains of microorganisms were detected in patients with AP and AspRF-CAP, respectively. The most common pathogens in AP were Corynebacterium striatum (17/213, 7.98%), Pseudomonas aeruginosa (15/213, 7.04%), Klebsiella pneumoniae (15/213, 7.04%), and Candida albicans (14/213, 6.57%). Besides, the most common pathogens in AspRF-CAP were Candida albicans (5/31, 16.13%), Pseudomonas aeruginosa (3/31, 9.68%) and Klebsiella pneumoniae (3/31, 9.68%). Moreover, Klebsiella pneumoniae (7/67, 10.45%) and Candida glabrata (5/67, 7.46%) were the most common pathogens among the 9 non-survived patients with AP.

Conclusion

The prevalent pathogens detected in cases of AP were Corynebacterium striatum, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Early combined detection methods for patients with AP enhance the positive detection rate of pathogens and potentially expedites the initiation of appropriate antibiotic therapeutic strategies.

Comparing biomechanics and neurophysiology between different phenotypes of patients with oropharyngeal dysphagia

The pathophysiology of oropharyngeal dysphagia (OD) across patient phenotypes may differ. The aim of this study was to compare the biomechanics and neurophysiology of swallowing between healthy volunteers (HVs) and patients with dysphagia as a consequence of aging (OOD), post-stroke (PSOD), Parkinson's disease (POD), or dementia (DOD). A retrospective study including 35 HVs and 109 OOD, 195 PSOD, 78 POD, and 143 DOD patients was performed. Videofluoroscopic data of signs of impaired efficacy and safety, penetration-aspiration scale (PAS) score, and the biomechanics of laryngeal vestibule closure (LVC) and opening (LVO) and of upper esophageal sphincter opening (UESO) were collected. Neurophysiology was assessed with pharyngeal sensory evoked potentials and neurotopography maps. All OD phenotypes showed signs of impaired efficacy and safety of swallowing, increased PAS score (p < 0.001), and delayed time to LVC (p < 0.0001). OOD (p < 0.0001), PSOD (p < 0.0001), and POD (p = 0.0065) patients also had delayed time to LVO, and OOD (p = 0.0062) and DOD (p = 0.0016) patients to UESO. Regarding neurophysiology, all phenotypes presented impaired pharyngeal sensitivity, a significant reduction in cortical activation, and impaired sensory input integration. Additionally, only PSOD was associated with impaired conduction of sensory stimuli. In conclusion, we found common but also specific pathophysiological elements. These results improve our understanding of OD pathophysiology and may help pave the way for phenotype-specific treatments.

Brain and Pharyngeal Responses Associated with Pharmacological Treatments for Oropharyngeal Dysphagia in Older Patients

Impaired pharyngo-laryngeal sensory function is a critical mechanism for oropharyngeal dysphagia (OD). Discovery of the TRP family in sensory nerves opens a window for new active treatments for OD. To summarize our experience of the action mechanism and therapeutic effects of pharyngeal sensory stimulation by TRPV1, TRPA1 and TRPM8 agonists in older patients with OD. Summary of our studies on location and expression of TRP in the human oropharynx and larynx, and clinical trials with acute and after 2 weeks of treatment with TRP agonists in older patients with OD. (1) TRP receptors are widely expressed in the human oropharynx and larynx: TRPV1 was localized in epithelial cells and TRPV1, TRPA1 and TRPM8 in sensory fibers mainly below the basal lamina. (2) Older people present a decline in pharyngeal sensory function, more severe in patients with OD associated with delayed swallow response, impaired airway protection and reduced spontaneous swallowing frequency. (3) Acute stimulation with TRP agonists improved the biomechanics and neurophysiology of swallowing in older patients with OD TRPV1 = TRPA1 > TRPM8. (4) After 2 weeks of treatment, TRPV1 agonists induced cortical changes that correlated with improvements in swallowing biomechanics. TRP agonists are well tolerated and do not induce any major adverse events. TRP receptors are widely expressed in the human oropharynx and larynx with specific patterns. Acute oropharyngeal sensory stimulation with TRP agonists improved neurophysiology, biomechanics of swallow response, and safety of swallowing. Subacute stimulation promotes brain plasticity further improving swallow function in older people with OD.

Shear-Viscosity-Dependent Effect of a Gum-Based Thickening Product on the Safety of Swallowing in Older Patients with Severe Oropharyngeal Dysphagia

Fluid thickening is a valid therapeutic strategy for patients with oropharyngeal dysphagia (OD). The main aim of this study was to determine the therapeutic effect of the xanthan-gum-based thickener Tsururinko Quickly (TQ, Morinaga Milk Co., Tokyo, Japan) in older patients with severe OD. A total of 85 patients (83.32 ± 6.75 y) with OD and a penetration-aspiration score (PAS) of n ≥ 3 were studied by videofluoroscopy while swallowing duplicate 10 mL boluses at <50 mPa·s, 100, 200, 400, 800, and 1600 mPa·s, to assess the safety and efficacy of swallowing and the biomechanics of a swallowing response at each viscosity level. At <50 mPa·s, only 16.25% patients swallowed safely, 45% had penetrations (PAS 3-5), and 38.75% had aspirations (PAS 6-8). Fluid thickening with TQ greatly increased the prevalence of patients with safe swallowing from 62.90% at 100 mPa·s to 95.24% at 1600 mPa·s in a shear-viscosity-dependent manner. The penetrations and aspirations were significantly reduced to 3.60% and 1.19%, respectively, at 1600 mPa·s. The threshold viscosity was 100 mPa·s and the increasing viscosity above 800 mPa·s did not further improve the therapeutic effect significantly. Increasing the shear viscosity significantly reduced the time to laryngeal vestibule closure (-16.70%), increased the time to upper oesophageal sphincter opening (+26.88%), and reduced the pharyngeal bolus velocity (-31.62%) without affecting the pharyngeal residue. TQ has a strong shear-viscosity-dependent effect on the safety of swallowing in older patients with severe OD without increasing the pharyngeal residue. The therapeutic range for TQ is 100-800 mPa·s, with 200 and 800 mPa·s being the optimal doses to cover the needs of older patients with OD.

Spontaneous Swallowing Frequency in Post-Stroke Patients with and Without Oropharyngeal Dysphagia: An Observational Study

Oropharyngeal dysphagia (OD) is a frequent complication after stroke (PSOD) that increases morbidity and mortality. Early detection of PSOD is essential to reduce morbidity and mortality in patients with acute stroke. In recent years, an association between reduced spontaneous swallowing frequency (SSF) and OD has been described. Likewise, the reduction of saliva substance P (SP) concentration has been associated with an increased risk of aspiration and a decrease in SSF. In this study we aimed to compare SSF, salivary SP concentration, hydration and nutritional status in post-stroke (PS) patients with and without OD. We included 45 acute PS patients (4.98 ± 2.80 days from stroke onset, 62.22% men, 71.78 ± 13.46 year). The Volume-Viscosity Swallowing Test (V-VST) was performed for clinical diagnosis of OD. SSF/minute was assessed through 10-min neurophysiological surface recordings including suprahyoid-electromyography and cricothyroid-accelerometry. Saliva samples were collected with a Salivette® to determine SP by ELISA. Hydration status was assessed by bioimpedance. Nutritional status was evaluated by Mini Nutritional Assessment Short Form (MNA-sf) and blood analysis. Twenty-seven PS patients (60%) had OD; 19 (40%), impaired safety of swallow. SSF was significantly reduced in PSOD, 0.23 ± 0.18 and PSOD with impaired safety, 0.22 ± 0.18 vs 0.48 ± 0.29 swallows/minute in PS without OD (PSnOD); (both p < 0.005). Nutritional risk was observed in 62.92% PSOD vs 11.11% PSnOD (p = 0.007) and visceral protein markers were also significantly reduced in PSOD (p < 0.05). Bioimpedance showed intracellular dehydration in 37.50% PSOD vs none in PSnOD. There were no differences for saliva SP concentrations. SSF is significantly reduced in PSOD in comparison with PSnOD. Acute PSOD patients present poor nutritional status, hydropenia, and high risk for respiratory complications.

A Systematic and Universal Artificial Intelligence Screening Method for Oropharyngeal Dysphagia: Improving Diagnosis Through Risk Management

Oropharyngeal dysphagia (OD) is underdiagnosed and current screening is costly. We aimed: (a) to develop an expert system (ES) based on machine learning that calculates the risk of OD from the electronic health records (EHR) of all hospitalized older patients during admission, and (b) to implement the ES in a general hospital. In an observational, retrospective study, EHR and swallowing assessment using the volume-viscosity swallow test for OD were captured over 24 months in patients > 70 yr admitted to Mataró Hospital. We studied the predictive power for OD of 25,000 variables. ES was obtained using feature selection, the final prediction model was built with non-linear methods (Random Forest). The database included 2809 older patients (mean age 82.47 ± 9.33 yr), severely dependent (Barthel Index 47.68 ± 31.90), with multiple readmissions (4.06 ± 7.52); 75.76% had OD. The psychometrics of the ES built with a non-linear model were: Area under the ROC Curve of 0.840; sensitivity 0.940; specificity, 0.416; Positive Predictive Value 0.834; Negative Predictive Value 0.690; positive likelihood ratio (LH), 1.61 and negative LH, 0.146. The ES screens in 6 s all patients admitted to a 419-bed hospital, identifies patients at greater risk of OD, and shows the risk for OD in the clinician's workstation. It is currently in use at our institution. Our ES provides accurate, systematic and universal screening for OD in real time during hospital admission of older patients, allowing the most appropriate diagnostic and therapeutic strategies to be selected for each patient.

COVID-19 is associated with oropharyngeal dysphagia and malnutrition in hospitalized patients during the spring 2020 wave of the pandemic

BACKGROUND & AIMS

Prevalence and complications of oropharyngeal dysphagia (OD) and malnutrition (MN) in COVID-19 patients is unknown. Our aim was to assess the prevalence, risk factors and clinical outcomes of OD and MN in a general hospital during the first wave of the COVID-19 pandemic.

METHODS

This was a prospective, observational study involving clinical assessment of OD (Volume-Viscosity Swallowing Test), and nutritional screening (NRS2002) and assessment (GLIM criteria) in COVID-19 patients hospitalized in general wards at the Consorci Sanitari del Maresme, Catalonia, Spain. The clinical characteristics and outcomes of patients were assessed at pre-admission, admission and discharge, and after 3 and 6-months follow-up.

RESULTS

We included 205 consecutive patients (69.28 ± 17.52 years, Charlson 3.74 ± 2.62, mean hospital stay 16.8 ± 13.0 days). At admission, Barthel Index was 81.3 ± 30.3; BMI 28.5 ± 5.4 kg/m2; OD prevalence 51.7% (44.1% impaired safety of swallow); and 45.5% developed MN with a mean weight loss of 10.1 ± 5.0 kg during hospitalization. OD was an independent risk factor for MN during hospitalization (OR 3.96 [1.45-10.75]), and hospitalization was prolonged in patients with MN compared with those without (21.9 ± 14.8 vs 11.9 ± 8.9 days, respectively; p < 0.0001). OD was independently associated with comorbidities, neurological symptoms, and low functionality. At 6-month follow-up, prevalence of OD was still 23.3% and that of MN only 7.1%. Patients with OD at discharge showed reduced 6-month survival than those without OD at discharge (71.6% vs 92.9%, p < 0.001); in contrast, those with MN at discharge did not show 6-month survival differences compared to those without (85.4% vs 83.8%, p = 0.8).

CONCLUSIONS

Prevalence and burden of OD and MN in patients hospitalized in COVID-19 wards is very high. Our results suggest that optimizing the management of MN might shorten the hospitalization period but optimizing the management of OD will likely impact the nutritional status of COVID-19 patients and improve their clinical outcomes and survival after hospital discharge.

CLINICALTRIALS

gov Identifier: NCT04346212.

Electrophysiological Measures of Swallowing Functions: A Systematic Review

The purpose of this systematic review was to examine the application of event-related potentials (ERPs) to investigate neural processes of swallowing functions in adults with and without dysphagia. Computerized literature searches were performed from three search engines. Studies were screened using Covidence (Cochrane tool) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement standards (PRISMA-2009). A total of 759 studies were initially retrieved, of which 12 studies met inclusion criteria. Electrophysiological measures assessing swallowing functions were identified in two major ERP categories: (1) sensory potentials and (2) pre-motor potentials. Approximately 80% of eligible studies demonstrated strong methodological quality, although most employed a case series or case-control study design. Pharyngeal sensory-evoked potentials (PSEPs) were used to assess pharyngeal afferent cortical processing. The temporal sequence of the PSEP waveforms varied based on the sensory stimuli. PSEPs were delayed with localized scalp maps in patients with dysphagia as compared to healthy controls. The pre-motor ERPs assessed the cortical substrates involved in motor planning for swallowing, with the following major neural substrates identified: pre-motor cortex, supplementary motor area, and primary sensorimotor cortex. The pre-motor ERPs differed in amplitude for the swallow task (saliva versus liquid swallow), and the neural networks differed for cued versus non-cued task of swallowing suggesting differences in cognitive processes. This systematic review describes the application of electrophysiological measures to assess swallowing function and the promising application for furthering understanding of the neural substrates of swallowing. Standardization of protocols for use of electrophysiological measures to examine swallowing would allow for aggregation of study data to inform clinical practice for dysphagia rehabilitation.

A Comparative Study between the Three Waves of the Pandemic on the Prevalence of Oropharyngeal Dysphagia and Malnutrition among Hospitalized Patients with COVID-19

BACKGROUND

The phenotype of patients affected by COVID-19 disease changed between the waves of the pandemic. We assessed the prevalence of oropharyngeal dysphagia (OD), malnutrition (MN), and mortality between the first three waves of COVID-19 patients in a general hospital.

METHODS

a prospective observational study between April 2020-May 2021. Clinical assessment for OD was made with the volume-viscosity swallowing test; nutritional assessment was performed consistent with GLIM criteria. A multimodal intervention was implemented in the second and third wave, including (a) texturized diets-fork mashable (1900 kcal + 90 g protein) or pureed (1700 kcal + 75 g protein), (b) oral nutritional supplements (500-600 kcal + 25-30 g protein), and (c) fluid thickening (250 mPa·s or 800 mPa·s).

RESULTS

We included 205 patients (69.3 ± 17.6 years) in the 1st, 200 (66.4 ± 17.5 years) in the 2nd, and 200 (72.0 ± 16.3 years;) in the 3rd wave (p = 0.004). On admission, prevalence of OD was 51.7%, 31.3% and 35.1%, and MN, 45.9%, 36.8% and 34.7%, respectively; mortality was 10.7%, 13.6% and 19.1%. OD was independently associated with age, delirium, and MN; MN, with age, OD, diarrhea and ICU admission; mortality, with age, OD and MN. (4) Conclusions: Prevalence of OD, MN and mortality was very high among COVID-19 patients. OD was independently associated with MN and mortality. An early and proactive multimodal nutritional intervention improved patients' nutritional status.

A Comparative Study on the Effect of Acute Pharyngeal Stimulation with TRP Agonists on the Biomechanics and Neurophysiology of Swallow Response in Patients with Oropharyngeal Dysphagia

Fluid thickening is the main compensatory strategy for patients with oropharyngeal dysphagia (OD) associated with aging or neurological diseases, and there is still no pharmacological treatment. We aimed to compare the effects of increasing bolus viscosity with that of acute stimulation with TRPV1, TRPA1 or TRPM8 agonists on the biomechanics and neurophysiology of swallow response in patients with OD. We retrospectively analyzed seven studies from our laboratory on 329 patients with OD. The effect of increasing shear viscosity up to 3682 mPa·s was compared by videofluoroscopy and pharyngeal sensory evoked potentials (pSEP) with that of adding to the bolus: capsaicin (TRPV1, 150 μM/10 μM), piperine (TRPA1/V1, 1 mM/150 μM), menthol (TRPM8, 1 mM/10 mM), cinnamaldehyde-zinc (TRPA1, 100 ppm−70 mM), citral (TRPA1, 250 ppm) or citral-isopulegol (TRPA1-TRPM8, 250 ppm−200 ppm). Fluid thickening improved the safety of swallow by 80% (p < 0.0001) by delaying bolus velocity by 20.7 ± 7.0% and time to laryngeal vestibule closure (LVC) by 23.1 ± 3.7%. Capsaicin 150μM or piperine 1 mM significantly improved safety of swallow by 50% (p < 0.01) and 57.1% (p < 0.01) by speeding time to LVC by 27.6% (p < 0.001) and 19.5% (p < 0.01) and bolus velocity by 24.8% (p < 0.01) and 16.9% (p < 0.05), respectively. Cinnamaldehyde-zinc shortened the P2 latency of pSEPs by 11.0% (p < 0.01) and reduced N2-P2 amplitude by 35% (p < 0.01). In conclusion, TRPV1 and TRPV1/A1 agonists are optimal candidates to develop new pharmacological strategies to promote the recovery of brain and swallow function in patients with chronic OD.

Oropharyngeal Dysphagia in Older People is Associated with Reduced Pharyngeal Sensitivity and Low Substance P and CGRP Concentration in Saliva

Substance P (SP) and Calcitonine gene-related peptide (CGRP) are released by sensory nerve fibers in the oropharynx. Patients with oropharyngeal dysphagia (OD) present reduced oropharyngeal sensitivity and low SP concentration in saliva. We aimed to assess the concentration of salivary SP and CGRP in healthy volunteers, and older people without and with OD, and the relationship with pharyngeal sensory threshold. We included 15 healthy volunteers, 14 healthy elderly and 14 elderly with OD. Swallow function was assessed by videofluoroscopy (VFS). Pharyngeal sensory threshold was assessed by intrapharyngeal electrical stimulation. Hydration and phase angle were assessed by bioimpedance. Saliva samples were collected with a Salivette® to determine SP and CGRP concentration by ELISA. Elderly patients with OD presented impaired safety of swallow (PAS 4.38 ± 0.77 p < 0.0001 vs. healthy volunteers = 1 and healthy elderly = 1.43 ± 0.51). Healthy elderly and elderly with OD presented a reduction in intracellular water and saliva volume (healthy elderly, 592.86 ± 327.79 μl, p = 0.0004; elderly with OD, 422.00 ± 343.01 μl, p = 0.0001 vs healthy volunteers, 1333.33 ± 615.91 μl, r = 0.6621, p < 0.0001). Elderly patients with OD presented an impairment in pharyngeal sensory threshold (10.80 ± 3.92 mA vs. healthy volunteers, 5.74 ± 2.57 mA; p = 0.007) and a reduction in salivary SP (129.34 pg/ml vs. healthy volunteers: 173.89 pg/ml; p = 0.2346) and CGRP levels (24.17 pg/ml vs. healthy volunteers: 508.18 pg/ml; p = 0.0058). There was a negative correlation between both SP and CGRP concentrations and pharyngeal sensory threshold (r = - 0.450, p = 0.024; r = - 0.4597, p = 0.036, respectively), but only SP identified elderly patients with OD with higher pharyngeal sensory threshold. Elderly patients with OD presented hydropenia and sarcopenia, reduced salivary SP and CGRP and impaired pharyngeal sensitivity. Our study suggests SP levels in saliva as a potential biomarker to monitor pharyngeal sensitivity in elderly patients with OD.

Effect of Aging, Gender and Sensory Stimulation of TRPV1 Receptors with Capsaicin on Spontaneous Swallowing Frequency in Patients with Oropharyngeal Dysphagia: A Proof-of-Concept Study

Spontaneous swallowing contributes to airway protection and depends on the activation of brainstem reflex circuits in the central pattern generator (CPG). We studied the effect of age and gender on spontaneous swallowing frequency (SSF) in healthy volunteers and assessed basal SSF and TRPV1 stimulation effect on SSF in patients with post-stroke oropharyngeal dysphagia (OD). The effect of age and gender on SSF was examined on 141 healthy adult volunteers (HV) divided into three groups: GI-18-39 yr, GII-40-59 yr, and GIII->60 yr. OD was assessed by the Volume-Viscosity Swallowing Test (VVST). The effect of sensory stimulation with capsaicin 10^-5 M (TRPV1 agonist) was evaluated in 17 patients with post-stroke OD, using the SSF. SSF was recorded in all participants during 10 min using surface electromyography (sEMG) of the suprahyoid muscles and an omnidirectional accelerometer placed over the cricothyroid cartilage. SSF was significantly reduced in GII (0.73 ± 0.50 swallows/min; p = 0.0385) and GIII (0.50 ± 0.31 swallows/min; p < 0.0001) compared to GI (1.03 ± 0.62 swallows/min), and there was a moderate significant correlation between age and SFF (r = -0.3810; p < 0.0001). No effect of gender on SSF was observed. Capsaicin caused a strong and significant increase in SSF after the TRPV1 stimulation when comparing to basal condition (pre-capsaicin: 0.41 ± 0.32 swallows/min vs post-capsaicin: 0.81 ± 0.51 swallow/min; p = 0.0003). OD in patients with post-stroke OD and acute stimulation with TRPV1 agonists caused a significant increase in SSF, further suggesting the potential role of pharmacological stimulation of sensory pathways as a therapeutic strategy for CPG activation in patients with OD.

Swallowing impairment in older adults: association with sensorimotor peripheral nerve function from the Health, Aging and Body Composition study

BACKGROUND

The purpose of this study was to examine whether impairments in sensorimotor peripheral nerve function are associated with a higher likelihood of swallowing impairment in older adults.

METHODS

Health, Aging and Body Composition participants (n = 607, age = 75.8 ± 2.7 years, 55.8% women, 32.3% black) underwent peripheral nerve testing at Year 4 and 11 with swallowing difficulty assessed at Year 4 and 15. Nerve conduction amplitude and velocity were measured at the peroneal motor nerve. Sensory nerve function was assessed with the vibration detection threshold and monofilament (1.4-g/10-g) testing at the big toe. Symptoms of lower extremity peripheral neuropathy and difficulty swallowing were collected by self-report. Data analysis was performed using a hierarchical approach. Odds ratios (ORs) were estimated using non-conditional logistic regression.

RESULTS

At Year 15 108 (17.8%) participants had swallowing impairments. In fully adjusted models, the peripheral nerve impairments associated with swallowing impairment were numbness (OR 4.67; 95%CI 2.24-9.75) and poor motor nerve conduction velocity (OR 2.26; 95%CI 1.08-4.70). Other peripheral nerve impairments were not related to swallowing.

CONCLUSIONS

The association between slow motor nerve conduction velocity and numbness and a higher likelihood of swallowing difficulties a decade later in our prospective study identifies an important area for further investigation in older adults.

Targeting the sensory feedback within the swallowing network-Reversing artificially induced pharyngolaryngeal hypesthesia by central and peripheral stimulation strategies

Pharyngolaryngeal hypesthesia is a major reason for dysphagia in various neurological diseases. Emerging neuromodulation devices have shown potential to foster dysphagia rehabilitation, but the optimal treatment strategy is unknown. Because functional imaging studies are difficult to conduct in severely ill patients, we induced a virtual sensory lesion in healthy volunteers and evaluated the effects of central and peripheral neurostimulation techniques. In a sham-controlled intervention study with crossover design on 10 participants, we tested the potential of (peripheral) pharyngeal electrical stimulation (PES) and (central) transcranial direct current stimulation (tDCS) to revert the effects of lidocaine-induced pharyngolaryngeal hypesthesia on central sensorimotor processing. Changes were observed during pharyngeal air-pulse stimulation and voluntary swallowing applying magnetoencephalography before and after the interventions. PES induced a significant (p < .05) increase of activation during swallowing in the bihemispheric sensorimotor network in alpha and low gamma frequency ranges, peaking in the right premotor and left primary sensory area, respectively. With pneumatic stimulation, significant activation increase was found after PES in high gamma peaking in the left premotor area. Significant changes of brain activation after tDCS could neither be detected for pneumatic stimulation nor for swallowing. Due to the peripheral cause of dysphagia in this model, PES was able to revert the detrimental effects of reduced sensory input on central processing, whereas tDCS was not. Results may have implications for therapeutic decisions in the clinical context.

Short-term neurophysiological effects of sensory pathway neurorehabilitation strategies on chronic poststroke oropharyngeal dysphagia

BACKGROUND

Neurorehabilitation strategies for chronic poststroke (PS) oropharyngeal dysphagia (OD) have been mainly focused on the neurostimulation of the pharyngeal motor cortex with only marginal effects. In contrast, treatments targeting the PS oropharyngeal sensory pathway dysfunction offer very promising results, but there is little knowledge on the underlying mechanisms. We aimed to explore the neurophysiological mechanisms behind the effect of three sensory neurostimulation strategies.

METHODS

We carried out a randomized two-blinded parallel group's crossover sham-controlled clinical trial in 36 patients with unilateral stroke and chronic unsafe swallow to investigate the effect of repetitive transcranial magnetic stimulation (rTMS) of the primary sensory cortex (A), oral capsaicin (B) and intra-pharyngeal electrical stimulation (IPES; C). The effect was evaluated immediately after the interventions with videofluoroscopy (VFS) and motor/sensory evoked potentials (MEP/SEP).

KEY RESULTS

Interventions induced no changes in the biomechanics of the swallow response during VFS. However, an enhancement of motor cortex excitability (latency shortening and increased size of thenar MEP) was found with active interventions (A + B + C, and B/C alone; P < .05 for all) but not with sham. Active but not sham interventions shortened pharyngeal SEP latency in the ipsilesional hemisphere (A + B + C: P2-peak, P = .039; A: N2-peak, P = .034) and antagonized the physiological habituation in pharyngeal MEP (A + B + C and A alone, P < .05 for both).

CONCLUSIONS AND INFERENCES

Sensory pathway neurostimulation strategies caused immediate enhancement of motor cortex excitability with peripheral strategies (capsaicin and IPES) and of pharyngeal sensory conduction with rTMS. These changes support the use of sensory neurorehabilitation strategies in promoting swallow recovery in chronic PS-OD.

Targeting Chemosensory Ion Channels in Peripheral Swallowing-Related Regions for the Management of Oropharyngeal Dysphagia

Oropharyngeal dysphagia, or difficulty in swallowing, is a major health problem that can lead to serious complications, such as pulmonary aspiration, malnutrition, dehydration, and pneumonia. The current clinical management of oropharyngeal dysphagia mainly focuses on compensatory strategies and swallowing exercises/maneuvers; however, studies have suggested their limited effectiveness for recovering swallowing physiology and for promoting neuroplasticity in swallowing-related neuronal networks. Several new and innovative strategies based on neurostimulation in peripheral and cortical swallowing-related regions have been investigated, and appear promising for the management of oropharyngeal dysphagia. The peripheral chemical neurostimulation strategy is one of the innovative strategies, and targets chemosensory ion channels expressed in peripheral swallowing-related regions. A considerable number of animal and human studies, including randomized clinical trials in patients with oropharyngeal dysphagia, have reported improvements in the efficacy, safety, and physiology of swallowing using this strategy. There is also evidence that neuroplasticity is promoted in swallowing-related neuronal networks with this strategy. The targeting of chemosensory ion channels in peripheral swallowing-related regions may therefore be a promising pharmacological treatment strategy for the management of oropharyngeal dysphagia. In this review, we focus on this strategy, including its possible neurophysiological and molecular mechanisms.

Therapeutic Effect, Rheological Properties and α-Amylase Resistance of a New Mixed Starch and Xanthan Gum Thickener on Four Different Phenotypes of Patients with Oropharyngeal Dysphagia

Thickened fluids are a therapeutic strategy for oropharyngeal dysphagia (OD). However, its therapeutic effect among different phenotypes of OD patients has not yet been compared. We aimed to assess the therapeutic effect and α-amylase resistance of a mixed gum/starch thickener [Fresubin Clear Thickener^® (FCT)] on four phenotypes of OD patients: G1) 36 older; G2) 31 head/neck cancer (HNC); G3) 30 Parkinson’s disease; and G4) 31 chronic post-stroke. Therapeutic effect of FCT was assessed during videofluoroscopy using the Penetration-Aspiration Scale (PAS), for 5/20 mL boluses, at four levels of shear-viscosity (<50, 250, 1000 and 2000 mPa·s). The effect of α-amylase was assessed after 30 s of oral incubation. Patients had high prevalence of VFS signs of impaired efficacy (98.44%) and safety (70.31%) of swallow with a severe PAS score (4.44 ± 0.20). Most severe OD was in HNC (80.6% unsafe swallows). FCT showed a strong therapeutic effect on the safety of swallow at a range between 250–1000 mPa·s (74.19–96.67%, safe swallows in G1, G3, G4, and 58.06% in G2), without increasing pharyngeal residue. Viscosity was unaffected by α-amylase. Increasing shear-viscosity with FCT causes a strong viscosity-dependent therapeutic effect on the safety of swallow. This effect depends on the phenotype and is similar among older, Parkinson’s and post-stroke patients.

A randomized clinical trial on the acute therapeutic effect of TRPA1 and TRPM8 agonists in patients with oropharyngeal dysphagia

BACKGROUND

Oropharyngeal dysphagia (OD) treatment is moving away from compensatory strategies toward active treatments that improve swallowing function. The aim of this study was to assess the acute therapeutic effect of TRPA1/M8 agonists in improving swallowing function in OD patients.

METHODS

Fifty-eight patients with OD caused by aging, stroke, or neurodegenerative disease were included in a three-arm, quadruple-blind, randomized clinical trial (NCT02193438). Swallowing safety and efficacy and the kinematics of the swallow response were assessed by videofluoroscopy (VFS) during the swallow of 182 ± 2 mPa·s viscosity (nectar) boluses of a xanthan gum thickener supplemented with (a) 756.6 μmol/L cinnamaldehyde and 70 μmol/L zinc (CIN-Zn) (TRPA1 agonists), (b) 1.6 mmol/L citral (CIT) (TRPA1 agonist), or (c) 1.6 mmol/L citral and 1.3 mmol/L isopulegol (CIT-ISO) (TRPA1 and TRPM8 agonists). The effects on pharyngeal event-related potentials (ERP) were assessed by electroencephalography.

KEY RESULTS

TRPA1 stimulation with either CIN-Zn or CIT reduced time to laryngeal vestibule closure (CIN-Zn P = .002, CIT P = .023) and upper esophageal sphincter opening (CIN-Zn P = .007, CIT P = .035). In addition, CIN-Zn reduced the penetration-aspiration scale score (P = .009), increased the prevalence of safe swallows (P = .041), and reduced the latency of the P2 peak of the ERP. CIT-ISO had no positive effect on biomechanics or neurophysiology. No significant adverse events were observed.

CONCLUSIONS AND INFERENCES

TRPA1 stimulation with CIN-Zn or CIT improves the swallow response which, in the case of CIN-Zn, is associated with a significant improvement in cortical activation and safety of swallow. These results provide the basis for the development of new active treatments for OD using TRPA1 agonists.

Acute and subacute effects of oropharyngeal sensory stimulation with TRPV1 agonists in older patients with oropharyngeal dysphagia: a biomechanical and neurophysiological randomized pilot study

BACKGROUND

Older people with oropharyngeal dysphagia (OD) present a decline in pharyngeal sensory function. The aim of this proof-of-concept study was to assess the biomechanical and neurophysiological effects of acute and subacute oropharyngeal sensory stimulation with transient receptor potential vanilloid 1 (TRPV1) agonists (capsaicinoids) in older patients with OD.

METHODS

We studied the effect of a single dose versus multiple doses (2 weeks) of oral capsaicin treatment (10^-5 M) or placebo in 28 older patients with OD (81.2 ± 4.6 years) using videofluoroscopy (penetration-aspiration scale [PAS], timing of swallow response) and electroencephalography (EEG) (latency and amplitude of pharyngeal event-related potential [ERP]).

RESULTS

Acute stimulation by capsaicinoids 10^-5 M did not improve swallow function and did not produce significant changes in pharyngeal ERP. In contrast, after 10 days of treatment, patients presented a clinically relevant and statistically significant reduction in the laryngeal vestibule closure (LVC) time (22.5%, p = 0.042), and in the PAS (24.2%, p = 0.038), compared with the placebo group. EEG results showed a reduction in the latency of the N1 peak (28.6%, p = 0.007) and an increase of the amplitude of the P1-N2 (59.4%, p = 0.038) and the N2-P2 (43.6%, p = 0.050) peaks. We observed a strong and significant correlation between the reduction in the latency of the N1 peak and change in LVC time after subacute treatment (r = 0.750, p = 0.003).

CONCLUSIONS

After 2 weeks of treatment, oropharyngeal sensory stimulation with capsaicinoids induced cortical changes that were correlated with improvements in swallowing biomechanics in older patients with OD. These results further show that sensory stimulation by TRPV1 agonists can become a useful pharmacological treatment for older patients with OD.

Triple Adaptation of the Mediterranean Diet: Design of A Meal Plan for Older People with Oropharyngeal Dysphagia Based on Home Cooking

BACKGROUND

Oropharyngeal dysphagia (OD) and malnutrition are highly prevalent in older patients that are discharged from general hospitals (47% and 30%, respectively).

AIMS

To develop a nutritional plan for these patients involving a triple adaptation of their traditional diet: (a) rheological adaptation (texture and viscosity) for safe deglutition, (b) nutritional adaptation (water, calories, and proteins), and (c) organoleptic adaptation to improve compliance.

METHODS

Two fluid viscosities (250 and 800 mPa·s) were selected according to previous studies on optimal viscosities in older patients. The British Dietetic Association food texture classification based on common clinical practice selected two food textures (thick purée and fork-mashable. Two levels of calorie protein enrichment were selected according to previous studies using the Mini Nutritional Assessment (MNA®).

RESULTS

The daily caloric-protein and hydric needs were established at 1750 kcal, 70 g protein, and 1750 mL water in patients with MNA® ≥ 17; and, 2037 kcal, 90 g protein, and 2000 mL water/day in malnourished patients. Sixteen weekly menus (296 recipes) were developed while using two textures, two levels of viscosity, two nutritional phenotypes (normal/at-risk vs. malnourished), and two seasons of the year (spring/summer-autumn/winter) based on Mediterranean cuisine.

CONCLUSION

This concept paper demonstrates that traditional Mediterranean cooking can be adapted to meet the rheological, nutritional, and hydration needs of older patients with OD. The recipes that we have developed meet the needs of patients with varying degrees of OD and malnutrition are reproducible in patient's homes and they could have a major impact on the clinical outcomes of these patients.

TRPM8, ASIC1, and ASIC3 localization and expression in the human oropharynx

BACKGROUND

Oropharyngeal dysphagia (OD) is a prevalent disease with poor prognosis among older people and has no pharmacological treatment. Polymodal sensory receptors like the TRP or ASIC family receptors are potential targets to treat OD. TRPM8 agonists and acidic solutions can improve the swallow response in patients with OD, but little is known about the expression of TRPM8, ASIC1, and ASIC3 in the human oropharynx. The aim of this study was to assess the expression and localization of TRPM8, ASIC1, and ASIC3 in human samples of the oropharynx to lay the basis for new pharmacological treatments for OD.

METHODS

Pathology-free samples from oropharyngeal regions innervated by cranial nerves V, IX, and X were obtained during major ENT surgery and processed to obtain mRNA (20 patients) or to be used in immunohistochemical assays (12 patients). TRPM8, ASIC1, and ASIC3 expression and localization were studied with RT-qPCR and fluorescent immunohistochemistry.

KEY RESULTS

ASIC3 was expressed in the 3 regions studied with similar levels and was localized on sensory fibers innervating the mucosa below the basal lamina of all studied regions. TRPM8 was also co-localized on the sensory fibers innervating the mucosa below the basal lamina of all studied regions. In contrast, ASIC1 was only found in the nerves innervating the tongue muscular fibers.

CONCLUSIONS & INFERENCES

TRPM8 and ASIC3 are found on submucosal sensory nerves in the human oropharynx. Our study lays the basis to use oropharyngeal TRPM8 and ASIC3 receptors as therapeutic targets to develop new active pharmacological treatments for OD patients.

Association between oropharyngeal dysphagia, oral functionality, and oral sensorimotor alteration

OBJECTIVE

To evaluate whether the oral functionality and the oral sensorimotor alterations are associated with oropharyngeal dysphagia in community-dwelling older persons and long-term care older residents.

METHODS

An exploratory study with 265 independent older persons of the southern state of Brazil. The diagnosis of dysphagia, as well as the condition of the oral sensorimotor system, was assessed by a speech-language therapist and the oral health status by a dentist. Poisson Regression with robust variance was used to calculate the crude and adjusted Prevalence Ratios (PR) and their respective confidence intervals of 95%.

RESULTS

The mean age was 73.5 (±8.9) years, women represented 59.2% of the sample. The frequency of dysphagia in the studied population was 45.3% (n = 120), being more frequent in the long-term care older residents (62.5%; n = 75) than in the community-dwelling older persons (37.5%; n = 45). Individuals with four or more oral sensorimotor alterations (PR = 2.01; 95% CI 1.27-3.18), as well as those who presented a non-functional oral status (PR = 1.61; 95% CI 1.02-2.54) presented a higher frequency of dysphagia. Subgroup analysis indicates the same trend of results, when stratified by community-dwelling older persons and long-term older residents.

CONCLUSION

A non-functional oral health status and oral sensorimotor alterations are associated with a higher prevalence of oropharyngeal dysphagia.

A comparative study on the therapeutic effect of TRPV1, TRPA1, and TRPM8 agonists on swallowing dysfunction associated with aging and neurological diseases

BACKGROUND

Oropharyngeal sensory impairment is a potential target to treat swallowing dysfunction in patients with oropharyngeal dysphagia (OD).

AIM

To assess the therapeutic effect of stimulating oropharyngeal sensory afferents with TRPV1, TRPA1, or TRPM8 agonists vs increasing bolus viscosity in older and neurologic patients with OD by comparing four studies of similar experimental design.

METHODS

Swallow function of 142 older patients with impaired safety of swallow at nectar ([50-350] mPa·s) viscosity was evaluated with videofluoroscopy (VFS) while treated with TRPV1 (150 μmol/L), TRPV1/A1 (150 μmol/L and 1 mmol/L), or TRPM8 (1 mmol/L or 10 mmol/L) agonists or modified starch (MS) at spoon thick viscosity (>1750 mPa·s).

RESULTS

TRPV1 stimulation with capsaicinoids reduced penetrations by 50%, pharyngeal residue by 80%, and LVC time by 24.38% and increased bolus velocity by 36.51%. TRPV1/A1 stimulation with piperine reduced penetrations by 56.32%, LVC time by 25.55% and increased bolus velocity by 23.63%. TRPM8 stimulation with menthol 1 mmol/L reduced penetrations by 37.5% while 10 mmol/L reduced LVC time by 18.44%. Thickeners reduced penetrations by 77.11%, but increased pharyngeal residue by 19.89%, delayed LVC by 41.73%, and reduced bolus velocity by 13.44%.

CONCLUSION

Natural capsaicinoids have a stronger therapeutic effect on VFS signs and swallow response by stimulating TRPV1 than TRPV1/A1 or TRPM8 agonists. While TRP stimulants increased bolus velocity and reduced swallow response times, thickeners reduced bolus velocity and further delayed the swallow response. This study sets the bases to develop new pharmacologic strategies for older patients with OD, moving away from compensation toward the recovery of swallow function.