Influence of attention and bolus volume on brain organization during swallowing

Acute Antipsychotic Use and Presence of Dysphagia Among Older Veterans with Heart Failure

OBJECTIVE

Examine whether new antipsychotic (AP) exposure is associated with dysphagia in hospitalized patients with heart failure (HF).

DESIGN

Retrospective cohort.

SETTINGS AND PARTICIPANTS

AP-naïve Veterans hospitalized with HF and subsequently discharged to a skilled nursing facility (SNF) between October 1, 2010, and November 30, 2019.

METHODS

We linked Veterans Health Administration (VHA) electronic medical records with Centers for Medicare & Medicaid (CMS) Minimum Data Set (MDS) version 3.0 assessments and CMS claims. The exposure variable was administration of ≥1 dose of a typical or atypical AP during hospitalization. Our main outcome measure was dysphagia presence defined by (1) inpatient dysphagia diagnosis codes and (2) the SNF admission MDS 3.0 swallowing-related items to examine post-acute care dysphagia status. Inverse probability of treatment weighting was used for risk adjustment.

RESULTS

The analytic cohort consisted of 29,591 Veterans (mean age 78.5 ± 10.0 years; female 2.9%; n = 865). Acute APs were administered to 9.9% (n = 2941). Those receiving APs had differences in prior dementia [37.1%, n = 1091, vs 22.3%, n = 5942; standardized mean difference (SMD) = 0.33] and hospital delirium diagnoses (7.7%, n = 227 vs 2.8%, n = 754; SMD = 0.22). Acute AP exposure was associated with nearly double the risk for hospital dysphagia diagnosis codes [adjusted (adj.) relative risk (RR) 1.9, 95% CI 1.8, 2.1]. At the SNF admission MDS assessment, acute AP administration during hospitalization was associated with an increased dysphagia risk (adj. RR 1.2, 95% CI 1.0, 1.5) both in the oral (adj. RR 1.7, 95% CI 1.2, 2.0) and pharyngeal phases (adj. RR 1.3, 95% CI 1.0, 1.7).

CONCLUSIONS AND IMPLICATIONS

In this retrospective study, AP medication exposure was associated with increased dysphagia coding and MDS assessment. Considering other adverse effects, acute AP should be cautiously administered during hospitalization, particularly in those with dementia. Swallowing function is critical to hydration, nutrition, and medical management of HF; therefore, when acute APs are initiated, a swallow evaluation should be considered.

Swallow-related Brain Activity in Post-total Laryngectomy Patients: A Case Series Study

Background

Total laryngectomy is a surgical procedure to completely remove the hyoid bone, larynx, and associated muscles as a curative treatment for laryngeal cancer. This leads to insufficient swallowing function with compensative movements of the residual tongue to propel the food bolus to the pharynx and esophagus. However, the neurophysiological mechanisms of compensative swallowing after total laryngectomy remain unclear. Recently, swallowing-related cortical activation such as event-related desynchronization (ERD) during swallowing has been reported in healthy participants and neurological patients with dysphagia. Abnormal ERD elucidates the pathophysiological cortical activities that are related to swallowing. No report has investigated ERD in post-total laryngectomy patients.

Case

We investigated ERD during volitional swallowing using electroencephalography in three male patients after total laryngectomy for laryngeal cancer (age and time after surgery: Case 1, 75 years, 10 years; Case 2, 85 years, 19 years; Case 3, 73 years, 19 years). In video fluorographic swallowing studies, we observed compensatory tongue movements such as posterior-inferior retraction of the tongue and contact on the posterior pharyngeal wall in all three cases. Significant ERD was localized in the bilateral medial sensorimotor areas and the left lateral parietal area in Case 1, in the bilateral frontal and left temporal areas in Case 2, and in the left prefrontal and premotor areas in Case 3.

Discussion

These results suggest that cortical activities related to swallowing might reflect cortical reorganization for modified swallowing movements of residual tongue muscles to compensate for reduced swallowing pressure in patients after total laryngectomy.

New horizons in understanding oral health and swallowing function within the context of frailty

Frailty is a complex and multidimensional condition wherein declines in physiologic reserve and function place individuals in a state of heightened vulnerability and decreased resiliency. There has been growing interest in both research and clinical settings to understand how to best define, assess and characterise frailty in older adults. To this end, various models and clinical assessment tools have been used to define and measure frailty. While differences exist among these models and tools, a common unifying theme is a focus on physical function and activity. Notably absent across many available conceptual models and clinical tools are items directly related to oral and swallowing function. This is an important oversight as widespread changes to both oral and swallowing function are evident in older adults. Indeed, emerging evidence suggests many of the functional domains affected in frail older adults, such as nutrition and sarcopenia, have cyclical relationships with impairments in oral (oral hypofunction) and swallowing function (dysphagia) as well. The increasing appreciation for the interrelationships among oral hypofunction, dysphagia and frailty provides an opportunity for refinement of frailty assessment and characterisation in older adults to incorporate metrics specific to oral and swallowing function.

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.

Can Swallowing Cerebral Neurophysiology Be Evaluated during Ecological Food Intake Conditions? A Systematic Literature Review

Swallowing is a complex function that relies on both brainstem and cerebral control. Cerebral neurofunctional evaluations are mostly based on functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), performed with the individual laying down; which is a non-ecological/non-natural position for swallowing. According to the PRISMA guidelines, a review of the non-invasive non-radiating neurofunctional tools, other than fMRI and PET, was conducted to explore the cerebral activity in swallowing during natural food intake, in accordance with the PRISMA guidelines. Using Embase and PubMed, we included human studies focusing on neurofunctional imaging during an ecologic swallowing task. From 5948 unique records, we retained 43 original articles, reporting on three different techniques: electroencephalography (EEG), magnetoencephalography (MEG) and functional near infra-red spectroscopy (fNIRS). During swallowing, all three techniques showed activity of the pericentral cortex. Variations were associated with the modality of the swallowing process (volitional or non-volitional) and the substance used (mostly water and saliva). All techniques have been used in both healthy and pathological conditions to explore the precise time course, localization or network structure of the swallowing cerebral activity, sometimes even more precisely than fMRI. EEG and MEG are the most advanced and mastered techniques but fNIRS is the most ready-to-use and the most therapeutically promising. Ongoing development of these techniques will support and improve our future understanding of the cerebral control of swallowing.

Phenotypic expression of swallowing function in Niemann-Pick disease type C1

Background

Niemann–Pick disease type C1 (NPC1) is a rare autosomal recessive disease characterized by endolysosomal accumulation of unesterified cholesterol with progressive deterioration in swallowing, often leading to premature death. Although documented, the natural history of NPC1 swallowing dysfunction has yet to be delineated systematically. This manuscript aims to provide a comprehensive characterization of the phenotypic spectrum and progression of swallowing dysfunction in NPC1.

Methodology

The National Institutes of Health (NIH) NPC1 natural history study (NCT00344331) enrolled 120 patients, who underwent comprehensive interpretative swallow assessments for swallowing safety, dietary modifications, and aspiration risk. Longitudinal statistical modeling accounted for all outcomes with NPC1 disease covariates (first symptom onset, age at neurological symptom onset, seizure history, duration of neurological symptoms) as well as miglustat use (a glucosylceramide synthase inhibitor) and NIH study duration (NIHSD; the length of time an individual participated in the NIH study). Probabilities for disease progression and time to swallowing decline were conducted for the entire cohort.

Results

Time to swallowing decline with American Speech-Language-Hearing Association National Outcome Measure (ASHA-NOMS) and the NIH-adapted Penetration Aspiration Scale (NIH-PAS) were identified: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{7.7}{100}$$\end{document}7.7100 person-years and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{9.8}{100}$$\end{document}9.8100 person-years, respectively. NIHSD and seizure history consistently and significantly were associated with decline (OR_NIHSD = 1.34–2.10, 95% CI 1.04–3.4, p = 0.001–0.026; OR_Seizure = 3.26–18.22, 1.03–167.79; p = 0.001–0.046), while miglustat use revealed protection (OR_Miglustat = 0.01–0.43, 0.007–0.98; p = 0.001–0.044). The probability of decline with NPC1 neurological severity scale and annual severity increment scale were established with the aforementioned covariates, varying amongst subgroups.

Conclusion

This study represents the most extensive collection of prospective, instrumental swallowing assessments in NPC1 to date with an interpretive analysis providing an improved understanding of NPC1 disease progression with swallowing function—serving as a foundation for clinical management and future NPC1 therapeutics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02472-w.

Case Report: Event-Related Desynchronization Observed During Volitional Swallow by Electroencephalography Recordings in ALS Patients With Dysphagia

Dysphagia is a severe disability affecting daily life in patients with amyotrophic lateral sclerosis (ALS). It is caused by degeneration of both the bulbar motor neurons and cortical motoneurons projecting to the oropharyngeal areas. A previous report showed decreased event-related desynchronization (ERD) in the medial sensorimotor areas in ALS dysphagic patients. In the process of degeneration, brain reorganization may also be induced in other areas than the sensorimotor cortices. Furthermore, ALS patients with dysphagia often show a longer duration of swallowing. However, there have been no reports on brain activity in other cortical areas and the time course of brain activity during prolonged swallowing in these patients. In this case report, we investigated the distribution and the time course of ERD and corticomuscular coherence (CMC) in the beta (15–25 Hz) frequency band during volitional swallow using electroencephalography (EEG) in two patients with ALS. Case 1 (a 71-year-old man) was diagnosed 2 years before the evaluation. His first symptom was muscle weakness in the right hand; 5 months later, dysphagia developed and exacerbated. Since his dietary intake decreased, he was given an implantable venous access port. Case 2 (a 64-year-old woman) was diagnosed 1 year before the evaluation. Her first symptom was open-nasal voice and dysarthria; 3 months later, dysphagia developed and exacerbated. She was given a percutaneous endoscopic gastrostomy. EEG recordings were performed during volitional swallowing, and the ERD was calculated. The average swallow durations were 7.6 ± 3.0 s in Case 1 and 8.3 ± 2.9 s in Case 2. The significant ERD was localized in the prefrontal and premotor areas and lasted from a few seconds after the initiation of swallowing to the end in Case 1. The ERD was localized in the lateral sensorimotor areas only at the initiation of swallowing in Case 2. CMC was not observed in either case. These results suggest that compensatory processes for cortical motor outputs might depend on individual patients and that a new therapeutic approach using ERD should be developed according to the individuality of ALS patients with dysphagia.

Event-Related Desynchronization and Corticomuscular Coherence Observed During Volitional Swallow by Electroencephalography Recordings in Humans

Swallowing in humans involves many cortical areas although it is partly mediated by a series of brainstem reflexes. Cortical motor commands are sent to muscles during swallow. Previous works using magnetoencephalography showed event-related desynchronization (ERD) during swallow and corticomuscular coherence (CMC) during tongue movements in the bilateral sensorimotor and motor-related areas. However, there have been few analogous works that use electroencephalography (EEG). We investigated the ERD and CMC in the bilateral sensorimotor, premotor, and inferior prefrontal areas during volitional swallow by EEG recordings in 18 healthy human subjects. As a result, we found a significant ERD in the beta frequency band and CMC in the theta, alpha, and beta frequency bands during swallow in those cortical areas. These results suggest that EEG can detect the desynchronized activity and oscillatory interaction between the cortex and pharyngeal muscles in the bilateral sensorimotor, premotor, and inferior prefrontal areas during volitional swallow in humans.