Swallowing after unilateral stroke of the cerebral cortex

Revealing Goal-Directed Neural Control of the Pharyngeal Phase of Swallowing

Swallowing is considered a three-phase mechanism involving the oral, pharyngeal, and esophageal phases. The pharyngeal phase relies on highly coordinated movements in the pharynx and larynx to move food through the aerodigestive crossing. While the brainstem has been identified as the primary control center for the pharyngeal phase of swallowing, existing evidence suggests that the higher brain regions can contribute to controlling the pharyngeal phase of swallowing to match the motor response to the current context and task at hand. This suggests that the pharyngeal phase of swallowing cannot be exclusively reflexive or voluntary but can be regulated by the two neural controlling systems, goal-directed and non-goal-directed. This capability allows the pharyngeal phase of swallowing to adjust appropriately based on cognitive input, learned knowledge, and predictions. This paper reviews existing evidence and accordingly develops a novel perspective to explain these capabilities of the pharyngeal phase of swallowing. This paper aims (1) to integrate and comprehend the neurophysiological mechanisms involved in the pharyngeal phase of swallowing, (2) to explore the reflexive (non-goal-directed) and voluntary (goal-directed) neural systems of controlling the pharyngeal phase of swallowing, (3) to provide a clinical translation regarding the pathologies of these two systems, and (4) to highlight the existing gaps in this area that require attention in future research. This paper, in particular, aims to explore the complex neurophysiology of the pharyngeal phase of swallowing, as its breakdown can lead to serious consequences such as aspiration pneumonia or death.

Poststroke Lingual Function and Swallowing Physiology

PURPOSE

Poststroke dysphagia is characterized by deficits in lingual function. However, correlations between lingual function and oral and pharyngeal swallowing impairments have not been well defined. The aim of this preliminary study was to explore if tongue pressure generative capacity in patients after ischemic stroke is associated with oropharyngeal swallowing impairments.

METHOD

A cross-sectional convenience sample of ischemic stroke patients underwent a videofluoroscopic swallowing study (VFSS) and completed measures of lingual function (Saliva Swallow Pressure, maximum isometric pressure [MIP], Maximum Isometric Endurance [ISO-M], and Maximum Isotonic Endurance [ISO-T]) using the Tongueometer and Iowa Oral Performance Instrument (IOPI) lingual manometry instruments. VFSS for each participant were consensus scored by two Modified Barium Swallow Impairment Profile (MBSImP)-certified raters. MBSImP Oral Total and Pharyngeal Total scores were calculated, and Swallow-by-Swallow MBSImP scores were summarized by calculating a percentage of the worst possible score across all bolus presentations for that score. Lingual measurements (swallow pressures, MIP, ISO-M, and ISO-T) were averaged across all participants, and Spearman's correlation coefficients were used to assess relationships between these lingual pressure measures and the MBSImP scores.

RESULTS

The final sample consisted of 39 participants post-ischemic stroke (ranging from 3 months to 27 months). Average MIP was 49.6 kPA (11.25), Saliva Swallow average was 19.0 kPa (11.25), average ISO-M was 11.1 s (12.65), and average ISO-T repetitions was 30 (22.8). There were significant, moderate correlations between ISO-M and Oral Total score (r = -.41, p = .0082); Component 1, Lip Closure (r = -.46, p = .0026); and Component 2, Tongue Control (r = -.48, p = .0016). All other correlations were nonsignificant.

CONCLUSIONS

Isometric endurance was correlated with physiologic measures of oral swallow function. Inclusion of endurance testing in poststroke populations may add value in clinical assessment. Future studies should examine the predictive value of lingual functional measures in predicting swallow dysfunction.

The Brain Lesion Affecting Dysphagia in Patient with Supratentorial Stroke

BackgroundDysphagia is a common sequela of stroke. However, specific swallowing impairments associated with brain lesions at different sites are not well characterized.ObjectiveThis study aimed to determine the relationship between the location of supratentorial brain lesions and the features of dysphagia.MethodsMedical records of patients with first-ever supratentorial stroke who underwent videofluoroscopic swallowing studies within 4 weeks of onset were retrospectively analyzed.ResultsA total of 158 patients (92 men and 66 women) were included. The lesions in internal capsule were associated with prolonged pharyngeal delay time (odds ratio [OR] 4.02, 95% confidence interval [CI] 1.13-14.28) and were inversely associated with post-swallowing vallecular residue (OR 0.55, 95% CI 0.32-0.95). The lesions in the insular cortex were associated with premature spillage and prolonged pharyngeal delay time (OR 2.27, 95% CI 1.08-4.76; OR 2.29, 95% CI 1.05-4.99, respectively). The lesions in the frontal lobe were associated with oral residue, vallecular residue, and pyriformis residue (OR 3.16, 95% CI 1.63-6.10; OR 3.06, 95% CI 1.55-6.02; OR 2.57, 95% CI 1.28-5.15, respectively).ConclusionsThis study revealed specific patterns of swallowing associated with specific brain lesions. Our findings may help elucidate the correlation between dysphagia patterns and the sites of brain lesions.

Swallowing Therapy Effects on Oral Muscle Mass, Tongue Function, Swallowing, and Nutrition in Stroke Patients with Dysphagia

BackgroundDysphagia, common post-stroke, elevates clinical risks. Muscle atrophy and compromised function correlate with malnutrition and secondary sarcopenia.ObjectiveWe studied oral muscle thickness, tongue strength/endurance in post-stroke dysphagia (PSD) using sonography and Iowa Oral Performance Instrument (IOPI), and assessed swallowing therapy's impact.Methods17 healthy and 15 PSD participants were analyzed. Healthy subjects underwent baseline sonography and IOPI. PSD patients received a 3-week swallowing therapy including traditional methods, neuromuscular electrical stimulation, and IOPI-guided oral exercises. Pre/post-swallowing therapy sonography and swallowing-related evaluations were conducted.ResutlsPSD group exhibited significant differences in affected masseter muscle thickness (P = 0.001), tongue strength (P ≤ 0.001), but not posterior tongue endurance (P = 0.066). After swallowing therapy, PSD patients showed notable improvement in masseter muscle thickness (P = 0.011) and tongue strength (P = 0.005-0.009). Clinical metrics like Functional Oral Intake Scale (P = 0.004), Mini Nutritional Assessment (P = 0.007), and gait speed (P = 0.018) also improved.ConclusionsStroke-induced dysphagia correlates with reduced masseter muscle thickness, tongue strength, and endurance. Swallowing therapy enhanced masseter muscle thickness and tongue strength, potentially improving swallowing function, nutrition, and gait speed.

Factors associated with oropharyngeal dysphagia and unsuccessful nasogastric tube removal after endovascular thrombectomy for anterior circulation stroke

PURPOSE

To identify the predictive variables for post-stroke dysphagia (PSD) among anterior circulation large vessel occlusion (LVO) stroke patients who underwent endovascular thrombectomy (EVT).

METHODS

This retrospective cohort study enrolled hospitalized patients with anterior LVO stroke who underwent EVT between January 1, 2018 and October 31, 2022. PSD was defined as the unsuccessful removal of the nasogastric (NG) tube. Factors, such as premorbid characteristics, laboratory results, EVT, rehabilitation-related parameters, and neuro-imaging, were analyzed for correlations to PSD at 4 and 12 weeks.

RESULTS

The study enrolled 136 patients, with a mean age of 72.9 ± 13.0 years, and 59 patients (43.4%) were male. At 4 weeks, 47.1% of the patients needed an NG tube, and at 12 weeks, 16.2% still required an NG tube. We found that lower albumin, lower body mass index (BMI), higher initial and 24-h post-EVT National Institute of Health Stroke Scale (NIHSS) scores, stroke-associated pneumonia, poor initial sitting balance and ability to sit up, insula or frontal operculum lesions, and bilateral hemisphere involvement were all associated with PSD at both 4 and 12 weeks in the univariate logistic regression. Multivariate analysis revealed that significant predictors of unsuccessful NG tube removal at 4 weeks included lower BMI (adjusted OR [aOR] 0.73, p = 0.005), hemorrhagic transformation (aOR 4.01, p = 0.0335), higher NIHSS scores at 24 h post-EVT (aOR 1.13, p = 0.0288), poor initial sitting ability (aOR 0.52, p = 0.0231), insular cortex ischemia (aOR 7.26, p = 0.0056), and bilateral hemisphere involvement (aOR 41.19, p < 0.0001). At 12 weeks, lower BMI (aOR 0.78, p = 0.0098), poor initial sitting balance (aOR 0.57, p = 0.0287), insular cortex lesions (aOR 4.83, p = 0.0092), and bilateral hemisphere involvement (aOR 4.07, p = 0.0139) remained significant predictors.

CONCLUSIONS

In patients with anterior LVO following EVT, PSD was associated with lower BMI, higher NIHSS scores, poor initial sitting balance and sitting ability, insular lesions, and bilateral hemisphere involvement.

Understanding the variability of the electrophysiologic laryngeal adductor reflex

OBJECTIVE

The laryngeal adductor reflex (LAR) is vital for airway protection and can be electrophysiologically obtained under intravenous general anesthesia (IGA). This makes the electrophysiologic LAR (eLAR) an important tool for monitoring of the vagus nerves and relevant brainstem circuitry during high-risk surgeries. We investigated the intra-class variability of normal and expected abnormal eLAR.

METHODS

Repeated measures of contralateral R1 (cR1) were performed under IGA in 58 patients. Data on presence/absence of cR2 and potential confounders were also collected. Review of neuroimaging, pathology and clinical exam, allowed classification into normal and expected abnormal eLAR groups. Using univariate and multivariate analysis we studied the variability of cR1 parameters and their differences between the two groups.

RESULTS

In both groups, cR1 latencies had coefficients of variation of <2%. In the abnormal group, cR1 had longer latencies, required higher activation currents and was more frequently desynchronized and unsustained; cR2 was more frequently absent.

CONCLUSIONS

cR1 latencies show high analytical precision for measurements. Delayed onset, difficult to elicit, desynchronized and unsustained cR1, and absence of cR2 signal an abnormal eLAR.

SIGNIFICANCE

Understanding the variability and behavior of normal and abnormal eLAR under IGA can aid in the interpretation of its changes during monitoring.

Correlation between lesion location and dysphagia characteristics in post-stroke patients

OBJECTIVE

To assess the correlation between lesion location and swallowing function characteristics in post-stroke dysphagia (PSD) patients.

MATERIALS AND METHODS

We enrolled 133 PSD. The patients were divided into supratentorial and infratentorial stroke groups. We compared the measurements in the videofluoroscopic swallowing study (VFSS) with 3ml and 5 ml of diluted and thickened barium liquid data between supratentorial and brainstem stroke groups. We further compared the difference of VFSS measurements between patients with left hemispheric or right hemispheric lesions (further divided into unilateral hemispheric cortical and subcortical subgroups) and brianstem leison stroke group.To explore the lesion location's effect on different bolus volume, the VFSS measurements of 3ml and 5ml in each subgroups were compared respectively. The measurements of VFSS included the oral transit time, soft palate elevation duration, hyoid bone movement duration (HMD), UES opening duration, pharyngeal transit duration (PTD), stage of ansition duration, and laryngeal closure duration (LCD), the upper esophageal sphincter opening (UESO), hyoid bone superior horizontal displacement, and hyoid bone anterior horizontal displacement. General swallowing function was assessed using the Penetration Aspiration Scale (PAS) and Functional Oral Intake Scale (FOIS). We performed the paired t-test, Spearman's correlation, and Kruskal-Wallis test analysis to characterize the parameters among the groups.

RESULTS

Fifty-eight patients were assessed in the final analysis. The HMD (p = 0.019), PTD (p = 0.048) and LCD (p = 0.013) were significantly different between the supratentorial and brainstem lesion groups in 5ml volume. The HMD was significantly different (p = 0.045) between the left cortical and brainstem lesion groups. Significant differences in the HMD (p = 0.037) and LCD (p = 0.032) between the left subcortical and brainstem lesion groups were found in 5ml volume bolus. There was no group different when taking the 3ml volume bolus. Regarding the relationship between food bolus volume and swallowing functions, only the UESO demonstrated a significant difference in the subcortical lesion of the right hemisphere (p = 0.0032) compared the 3 ml and 5 ml volume bolus. The PTD demonstrated a moderate correlation with the PAS scores (r = 0.38, p = 0.0044). The HMD (r = 0.32, p = 0.018) and LCD (r = 0.29, p = 0.039) demonstrated weak correlations with the PAS scores. We did not identify any correlation between the VFSS parameters and FOIS scores in each subgroup level.

CONCLUSION

The PSD with brainstem lesion shows more sever dysfunction in the pharyngeal phases. The left hemisphere was engaged in both the oral and pharyngeal phases. Lesions in the bilateral cortical, subcortical, and brainstem regions may impair sensory input.

Health Factors Associated With Development and Severity of Poststroke Dysphagia: An Epidemiological Investigation

BACKGROUND

Dysphagia after stroke is common and can impact morbidity and death. The purpose of this population-based study was to determine specific epidemiological and health risk factors that impact development of dysphagia after acute stroke.

METHODS AND RESULTS

Ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review from the GCNKSS (Greater Cincinnati Northern Kentucky Stroke Study), a representative sample of ≈1.3 million adults from southwestern Ohio and northern Kentucky. Dysphagia status was determined on the basis of clinical assessments and necessity for alternative access to nutrition via nasogastric or percutaneous endoscopic gastrostomy tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and premorbid conditions. Multivariable logistic regression determined factors associated with increased risk of dysphagia. Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed that increased age, Black race, higher National Institutes of Health Stroke Scale score at admission, having a hemorrhagic stroke (versus infarct), and right hemispheric stroke increased the risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower prestroke modified Rankin Scale score, and white matter disease.

CONCLUSIONS

This study replicated previous findings of variables associated with dysphagia (older age, worse stroke, right-sided hemorrhagic lesions), whereas other variables identified were without clear biological rationale (eg, Black race, history of high cholesterol, and presence of white matter disease) and should be investigated in future studies to determine biological relevance and potential influence in stroke recovery.

The Cortical and Subcortical Neural Control of Swallowing: A Narrative Review

Swallowing is a sophisticated process involving the precise and timely coordination of the central and peripheral nervous systems, along with the musculatures of the oral cavity, pharynx, and airway. The role of the infratentorial neural structure, including the swallowing central pattern generator and cranial nerve nuclei, has been described in greater detail compared with both the cortical and subcortical neural structures. Nonetheless, accumulated data from analysis of swallowing performance in patients with different neurological diseases and conditions, along with results from neurophysiological studies of normal swallowing have gradually enhanced understanding of the role of cortical and subcortical neural structures in swallowing, potentially leading to the development of treatment modalities for patients suffering from dysphagia. This review article summarizes findings about the role of both cortical and subcortical neural structures in swallowing based on results from neurophysiological studies and studies of various neurological diseases. In sum, cortical regions are mainly in charge of initiation and coordination of swallowing after receiving afferent information, while subcortical structures including basal ganglia and thalamus are responsible for movement control and regulation during swallowing through the cortico-basal ganglia-thalamo-cortical loop. This article also presents how cortical and subcortical neural structures interact with each other to generate the swallowing response. In addition, we provided the updated evidence about the clinical applications and efficacy of neuromodulation techniques, including both non-invasive brain stimulation and deep brain stimulation on dysphagia.

The relationship between dysphagia and the localisation of brain lesion in stroke: is the involvement of the pons and medulla important?

OBJECTIVES

The presence of dysphagia in stroke is associated with mortality and morbidity. The aim of this retrospective study is to present the relationship between dysphagia and the demographic characteristics of the patient, and the type and localisation of brain lesion in the acute period in stroke patients with dysphagia.

MATERIALS AND METHODS

The data of 284 patients who had stroke-related dysphagia, had a disease duration 1-3 months, had no history of swallowing dysfunction before the event, and had their brain MRI/CT reports in the hospital were included.

RESULTS

The rate of tube-dependent oral areas was higher in the lesions located in the pons and the medulla than in the lesions located in the MCA cortex, the basal ganglia, and the cerebellum (p ˂ 0.001, p = 0.032 and p = 0.011, respectively) and the percentage of those fed with NG + TPN + PEG was statistically significantly higher (p = 0.002, p = 0.032 and p = 0.011, respectively). History of pneumonia was found to be statistically significantly higher in the lesions located in the pons and the medulla than in the lesions located in the MCA cortex, ACA cortex, PCA cortex, the basal ganglia, periventricular white matter, the thalamus, the cerebellum, and the midbrain (p ˂ 0.001, p = 0.005, p = 0.023, p ˂ 0.001, p = 0.023, p = 0.001, p = 0.011 and p = 0.023, respectively).

CONCLUSION

In conclusion, although lesion localisation in the acute period in patients with dysphagia varied in terms of clinical swallowing evaluation findings, weight loss, pneumonia history, the rate of tube-dependent intake, were shown to be higher in patients who had lesions in the pons and the medulla, which is a finding that should be considered in the clinical follow-up of acute stroke patients with lesions in the pons and the medulla.

Biomechanical and Cortical Control of Tongue Movements During Chewing and Swallowing

Tongue function is vital for chewing and swallowing and lingual dysfunction is often associated with dysphagia. Better treatment of dysphagia depends on a better understanding of hyolingual morphology, biomechanics, and neural control in humans and animal models. Recent research has revealed significant variation among animal models in morphology of the hyoid chain and suprahyoid muscles which may be associated with variation in swallowing mechanisms. The recent deployment of XROMM (X-ray Reconstruction of Moving Morphology) to quantify 3D hyolingual kinematics has revealed new details on flexion and roll of the tongue during chewing in animal models, movements similar to those used by humans. XROMM-based studies of swallowing in macaques have falsified traditional hypotheses of mechanisms of tongue base retraction during swallowing, and literature review suggests that other animal models may employ a diversity of mechanisms of tongue base retraction. There is variation among animal models in distribution of hyolingual proprioceptors but how that might be related to lingual mechanics is unknown. In macaque monkeys, tongue kinematics-shape and movement-are strongly encoded in neural activity in orofacial primary motor cortex, giving optimism for development of brain-machine interfaces for assisting recovery of lingual function after stroke. However, more research on hyolingual biomechanics and control is needed for technologies interfacing the nervous system with the hyolingual apparatus to become a reality.

Quantitative Analysis of Temporal Parameters Correlated with Aspiration and Lesion Location in Stroke Patients

The purpose of this study was to identify differences in temporal parameters correlating to the presence of aspiration and the severity of penetration-aspiration scale (PAS) in patients with dysphagia after stroke. We also investigated whether there was a significant difference in temporal parameters based on the location of the stroke lesion. A total of 91 patient videofluoroscopic swallowing study (VFSS) videos of stroke patients with dysphagia were retrospectively analyzed. Various temporal parameters including oral phase duration, pharyngeal delay time, pharyngeal response time, pharyngeal transit time, laryngeal vestibule closure reaction time, laryngeal vestibule closure duration, upper esophageal sphincter opening duration and upper esophageal sphincter reaction time were measured. Subjects were grouped by the presence of aspiration, PAS score, and location of the stroke lesion. Pharyngeal response time, laryngeal vestibule closure duration, and upper esophageal sphincter opening duration were significantly prolonged in the aspiration group. These three factors showed positive correlation with PAS. In terms of stroke lesion, oral phase duration was significantly prolonged in the supratentorial lesion group, while upper esophageal sphincter opening duration was significantly prolonged in the infratentorial lesion group. We have demonstrated that quantitative temporal analysis of VFSS can be a clinically valuable tool identifying dysphagia pattern associated with stroke lesion or aspiration risk.

Health factors associated with development and severity of post-stroke dysphagia: an epidemiological investigation

Background and Purpose

Dysphagia is a common post-stroke occurrence and has been shown to impact patients' morbidity and mortality. The purpose of this study was to use a large population-based dataset to determine specific epidemiological and patient health risk factors that impact development and severity of dysphagia after acute stroke.

Methods

Using data from the Greater Cincinnati Northern Kentucky Stroke Study, GCNKSS, involving a representative sample of approximately 1.3 million people from Southwest Ohio and Northern Kentucky of adults (age ≥18), ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review. Dysphagia status was determined based on bedside and clinical assessments, and severity by necessity for alternative access to nutrition via nasogastric (NG) or percutaneous endoscopic gastrostomy (PEG) tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and pre-morbid conditions. Multivariable logistic regression was used to determine factors associated with increased risk of developing dysphagia.

Results

Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed: increased age, Black race, higher NIHSS score at admission, having a hemorrhagic stroke (vs infarct), and right hemispheric stroke increased risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower pre-stroke mRS score, and white matter disease.

Conclusions

This study replicated many previous findings of variables associated with dysphagia (older age, worse stroke, right sided hemorrhagic lesions), while other variables identified were without clear biological rationale (e.g. Black race, history of high cholesterol and presence of white matter disease). These factors should be investigated in future, prospective studies to determine biological relevance and potential influence in stroke recovery.

A Case of Swallowing Apraxia Due to Acute Infarct in the Right Precentral Gyrus

Swallowing apraxia is an intriguing type of apraxia where the patient cannot swallow despite normal neurological examinations including motor, sensory and cerebellar function. In this case report, we present a 60-year-old hypertensive male with swallowing apraxia. There was no attempt to swallow when food materials were given inside his mouth. Although he had normal examination findings including intact lip, tongue, palatal movement, and gag reflex. His cognition was also intact, as he could follow simple commands accurately. Except for a small infarct in the right precentral gyrus in the MRI (Magnetic Resonance Imaging) of the brain, his investigation findings were normal. We treated him with nasogastric feeding, and he gradually recovered over a month. Clinicians should consider swallowing apraxia as one of the clinical features of stroke when patients present with acute onset of swallowing problems. This case report is believed to increase awareness regarding this condition and add valuable information to relevant further studies.

Effect of Oral Apraxia on Dysphagia in Patients with Subacute Stroke

Aim of this study was to investigate the effect of post-stroke oral apraxia on dysphagia in patients with subacute stroke. We retrospectively analyzed the clinical data of 130 supratentorial stroke patients from January 2015 to February 2021 who underwent a formal limb and oral apraxia test and videofluoroscopic swallowing study (VFSS), and we compared the patients in two groups: the apraxia and non-apraxia (oral apraxia score > 45 and ≤ 45 points, respectively). All the patients participated in the standardized testing battery. The test variables were videofluoroscopic dysphagia scale (VDS), oral transit time (OTT), pharyngeal delay time (PDT), pharyngeal transit time, and penetration-aspiration scale (PAS); we conducted multivariable regression analysis with those parameters to confirm the significance of oral apraxia as a clinical determinant of post-stroke dysphagia. The mean oral apraxia scores were 38.4 and 47.6 points in the apraxia and non-apraxia groups, respectively (p < 0.001). The apraxia group had a higher proportion of delayed OTT for the 2-mL-thick liquid than the non-apraxia group (17.6% and 4.2%, respectively; p = 0.011). Oral apraxia was a significant determinant of VDS (p < 0.001), delayed OTT of 2-mL-thick liquids (p = 0.028), delayed PDT of cup drinking for thin liquid (p = 0.044), and PAS scores (p = 0.003). The presence of oral apraxia was significantly associated with dysphagia, especially with the VFSS parameters of the oral phase (thick liquid), pharyngeal phase (cup drinking for thin liquid) of swallowing, and increased risk of aspiration in subacute stroke patients. Thus, a formal assessment of oral apraxia is needed for stroke patients with dysphagia.

Cerebral control of swallowing: An update on neurobehavioral evidence

This review aims to update the current knowledge on the cerebral control of swallowing. We review data from both animal and human studies spanning across the fields of neuroanatomy, neurophysiology and neuroimaging to evaluate advancements in our understanding in the brain's role in swallowing. Studies have collectively shown that swallowing is mediated by multiple distinct cortical and subcortical regions and that lesions to these regions can result in dysphagia. These regions are functionally connected in separate groups within and between the two hemispheres. While hemispheric dominance for swallowing has been reported in most human studies, the laterality is inconsistent across individuals. Moreover, there is a shift in activation location and laterality between swallowing preparation and execution, although such activation changes are less well-defined than that for limb motor control. Finally, we discussed recent neurostimulation treatments that may be beneficial for dysphagia after brain injury through promoting the reorganization of the swallowing neural network.

Profiles of Swallowing Impairment in a Cohort of Patients With Reduced Tongue Strength Within 3 Months of Cerebral Ischemic Stroke

PURPOSE

Patients with poststroke dysphagia may experience inefficient bolus clearance or inadequate airway protection. Following a stroke, impairments in lingual pressure generation capacity are thought to contribute to oropharyngeal dysphagia. The goal of our study was to determine whether similar profiles of swallowing impairment would be seen across a cohort of patients with reduced tongue strength within 3 months after cerebral ischemic stroke.

METHOD

The sample comprised six adults with reduced tongue strength (i.e., maximum anterior isometric pressure < 40 kPa). Participants underwent a videofluoroscopy according to a standard protocol. Post hoc blinded ratings were completed using the Analysis of Swallowing Physiology: Events, Kinematics and Timing Method and coded as "typical" versus "atypical" (i.e., within vs. outside the healthy interquartile range) in comparison to published reference values.

RESULTS

The videofluoroscopies suggested that having reduced tongue strength did not translate into a common profile. Of the six participants, two showed Penetration-Aspiration Scale (PAS) scores of ≥ 3 on thin liquids, associated with incomplete laryngeal vestibule closure (LVC). Another two participants displayed PAS scores of 2 (transient penetration), but these were not associated with incomplete LVC. Pharyngeal residue, above the healthy 75th percentile, was seen for three participants. Five participants presented with atypical reductions in hyoid XY peak position.

CONCLUSIONS

In this cohort of adults within 3 months of cerebral ischemic stroke, reductions in tongue strength presented alongside a variety of changes in swallowing physiology. There was no straightforward relationship linking reduced tongue strength to particular patterns of impairment on videofluoroscopy.

Reliability of the Penetration-Aspiration Scale and Temporal and Clearance Measures in Poststroke Dysphagia: Videofluoroscopic Analysis From the Swallowing Treatment using Electrical Pharyngeal Stimulation Trial

PURPOSE

Information on reliability of outcome measures used to assess the effectiveness of interventions in dysphagia rehabilitation is lacking, particularly when used by different research groups. Here, we report on reliability of the penetration-aspiration scale (PAS) and temporal and clearance measures, determined using videofluoroscopy.

METHOD

Secondary analysis used videofluoroscopies from the Swallowing Treatment using Electrical Pharyngeal Stimulation trial in subacute stroke. PAS scores (719 scores from 18 participants) were evaluated and compared to the original PAS scores from the trial. Five conditions were assessed, including reliability for every swallow and overall mean of the worst PAS score. Operational rules for assessing temporal and clearance measures were also developed using the same data, and reliability of these rules was assessed. Reliability of component-level and derivative-level scores was assessed using the intraclass correlation coefficient (ICC) and weighted kappa.

RESULTS

Image quality was variable. Interrater reliability for the overall mean of the worst PAS score was excellent (ICC = .914, 95% confidence interval [CI] [.853, .951]) but moderate for every swallow in the bolus (ICC = .743, 95% CI [.708, .775]). Intrarater reliability for PAS was excellent (all conditions). Excellent reliability (both inter- and intrarater > .90) was seen for temporal measures of stage transition duration (ICC = .998, 95% CI [.993, .999] and ICC = .995, 95% CI [.987, .998], respectively) as well as initiation of laryngeal closure and pharyngeal transit time and all individual swallow events. Strong scores were obtained for some clearance measures; others were moderate or weak.

CONCLUSIONS

Interrater reliability for PAS is acceptable but depends on how the PAS scores are handled in the analysis. Interrater reliability for most temporal measures was high, although some measures required additional training. No clearance measures had excellent reliability.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19090088.

Systematic Review and Meta-Analysis of Dysphagia and Associated Pneumonia in Patients With Stroke From India: A Call to Arms

OBJECTIVES

This study aimed to determine the prevalence of reported dysphagia and associated pneumonia risk among patients with stroke in India.

METHOD

We carried out a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The primary outcome of interest was dysphagia and pneumonia among patients with stroke in India. Two review authors independently assessed the quality of studies using the Newcastle-Ottawa Scale and extracted related data. Meta-analysis was performed for frequency of dysphagia, associated pneumonia, and its relative risk using a random-effects model. Statistical heterogeneity was computed using the I² index.

RESULTS

A total of 3,644 titles were screened, and only eight studies met our inclusion criteria. Based on data from these studies, we calculated the pooled prevalence of dysphagia (47.71%; 95% confidence interval [CI] [20.49%, 70.92%], p < .001) and pneumonia (20.43%; 95% CI [10.73%, 30.14%], p < .001) for patients with stroke in India. We found that the relative risks of pneumonia in patients with stroke and dysphagia versus those patients with stroke and no dysphagia was 9.41 (95% CI [5.60, 15.80], p < .001). Data on length of hospital stay and rates of mortality secondary to pneumonia are also presented.

CONCLUSIONS

Despite the high incidence of dysphagia and associated pneumonia, the methodological quality of studies is fair and there is little research focused on epidemiological data. We call to arms to those SLPs working with patients with stroke in India to become proactive in both clinical practice and research domains. Supplemental Material https://doi.org/10.23641/asha.17701022.

Advances in Swallowing Neurophysiology across Pediatric Development: Current Evidence and Insights

Purpose of Review

This review article analyzes current evidence on the neurophysiology of swallowing during development and offers expert opinion on clinical implications and future research directions.

Recent Findings

In the past five years, basic and clinical research has offered advances in our understanding of pediatric swallowing neurophysiology. Animal models have elucidated the role of brainstem circuits and the peripheral and central nervous system in neonatal swallowing. Recent human studies have further showcased that fetal and infant swallowing require cerebral inputs in order to develop functionally. Finally, neurophysiological and neuroimaging studies are starting to better define these cerebral inputs, as well as neuroplastic adaptations that may be needed for optimal feeding development.

Summary

The neural development of swallowing is a complex and dynamic process. Continued research is needed to better understand influences on swallowing neural development, which can be essential for improving prevention, diagnosis, and interventions for pediatric dysphagia.

Voxel-based lesion symptom mapping analysis for dysphagia in stroke patients with isolated cerebellar lesions

Because the cerebellum plays a role in motor coordination, timing, sequencing, and feedback, it is hypothesized to be involved in swallowing-related functions. The role of the cerebellum in deglutition has become increasing evident, but the exact nature of this role remains inconclusive because of limited data from pure cerebellar lesions. Therefore, we conducted location analysis in isolated cerebellar lesions to complement previous findings and provide additional information. We reviewed 40 stroke patients with isolated cerebellar lesion. Lesion location and volume were measured on brain magnetic resonance images. We generated statistical maps of lesions related to VDS using voxel-based lesion symptom mapping (VLSM). We also created an overlay map of subgroups according to VDS score, those who have low risk and those who have high risk. Patients with cerebellar lesion had difficulty swallowing, both in the oral and pharyngeal phases. Multivariate analysis of cognitive function was selected as an independent predictor. In the group of high-risk patients, the overlay map showed some bilateral asymmetry, with a wider distribution in the left hemisphere and involvement of deep cerebellar nuclei. Using VLSM, we found that lesion location was associated with dysphagia. Although these results were not statistically significant, they showed a lesion pattern with predominant distribution in the left posterior lobe. Our results suggest that damage to the posterior lobe of the left cerebellum tends be related to severity of dysphagia in patients with isolated cerebellar lesion.

Jaw-retraction exercise increases anterior hyoid excursion during swallowing in older adults with mild dysphagia

OBJECTIVES

The present study aimed to evaluate the effectiveness of a newly designed jaw-retraction exercise for strengthening the geniohyoid muscle and thus improving the anterior movement of the hyoid bone during swallowing.

BACKGROUND

Although previous studies suggest a relationship between anterior hyoid excursion and upper esophageal sphincter (UES) opening, there are currently no reports of physical exercises without the use of special equipment that can effectively improve this movement of the hyoid bone during swallowing.

MATERIALS AND METHODS

This before-after study included patients presenting to the authors' hospital with mild dysphagia (Level 5 on the Dysphagia Outcome and Severity Scale). The participants were instructed to perform a jaw-retraction exercise designed to strengthen the geniohyoid muscle. Each participant was instructed to perform two sets of the exercise daily for four weeks, with each set consisting of five repetitions. Before and after the four-week training period, videofluoroscopic swallowing studies were performed and later analysed.

RESULTS

Twenty-five patients with a median age of 77 were included. The median peak anterior hyoid position before and after exercise were 129.82 and 132.74 (%C2-C4 length), respectively, and this increase was found to be significant (P = .007). The median extent of UES opening before and after exercise were 8.6 and 9.3 (mm), respectively, and this increase was also found to be significant (P = .040).

CONCLUSION

Our findings demonstrate that the jaw-retraction exercise can effectively improve the anterior movement of the hyoid bone. This exercise may be effective in individuals with oral frailty when signs of swallowing disorders are observed.

The Role of White Matter in the Neural Control of Swallowing: A Systematic Review

Background: Swallowing disorders (dysphagia) can negatively impact quality of life and health. For clinicians and researchers seeking to improve outcomes for patients with dysphagia, understanding the neural control of swallowing is critical. The role of gray matter in swallowing control has been extensively documented, but knowledge is limited regarding the contributions of white matter. Our aim was to identify, evaluate, and summarize the populations, methods, and results of published articles describing the role of white matter in neural control of swallowing.

Methods: We completed a systematic review with a multi-engine search following PRISMA-P 2015 standards. Two authors screened articles and completed blind full-text review and quality assessments using an adapted U.S. National Institute of Health's Quality Assessment. The senior author resolved any disagreements. Qualitative synthesis of evidence was completed.

Results: The search yielded 105 non-duplicate articles, twenty-two of which met inclusion criteria. Twenty were rated as Good (5/22; 23%) or Fair (15/22; 68%) quality. Stroke was the most represented diagnosis (n = 20; 91%). All studies were observational, and half were retrospective cohort design. The majority of studies (13/22; 59%) quantified white matter damage with lesion-based methods, whereas 7/22 (32%) described intrinsic characteristics of white matter using methods like fractional anisotropy. Fifteen studies (68%) used instrumental methods for swallowing evaluations. White matter areas commonly implicated in swallowing control included the pyramidal tract, internal capsule, corona radiata, superior longitudinal fasciculus, external capsule, and corpus callosum. Additional noteworthy themes included: severity of white matter damage is related to dysphagia severity; bilateral white matter lesions appear particularly disruptive to swallowing; and white matter adaptation can facilitate dysphagia recovery. Gaps in the literature included limited sample size and populations, lack of in-depth evaluations, and issues with research design.

Conclusion: Although traditionally understudied, there is sufficient evidence to conclude that white matter is critical in the neural control of swallowing. The reviewed studies indicated that white matter damage can be directly tied to swallowing deficits, and several white matter structures were implicated across studies. Further well-designed interdisciplinary research is needed to understand white matter's role in neural control of normal swallowing and in dysphagia recovery and rehabilitation.

Effects of dual-task interference on swallowing in healthy aging adults

A wide body of literature has demonstrated that the neural representation of healthy swallowing is mostly bilateral, with one hemisphere dominant over the other. While several studies have demonstrated the presence of laterality for swallowing related functions among young adults, the data on older adults are still growing. The purpose of this paper is to investigate potential changes in hemispheric dominance in healthy aging adults for swallowing related tasks using a behavioral dual-task paradigm. A modified dual-task paradigm was designed to investigate the potential reduction in hemispherical specialization for swallowing function. Eighty healthy right-handed participants in the study were divided into two groups [Group 1: young adults (18–40 years) and Group 2: older adults (65 and above)]. All the participants performed a timed water swallow test at baseline and with two interference conditions (silent word repetition, and facial recognition). The results of the study revealed the following 1) a statistically significant effect of age on swallow performance; 2) statistically significant effect of each of the interference tasks on two of the swallow measures (VPS and VPT) in younger adults; and 3) no significant effect of the interference tasks on the swallowing performance of older adults. These findings suggest that aging substantially affects swallowing in older individuals, and this potentially accompanies a reduction in the hemispheric specialization for swallowing related tasks.

Neural correlates of cricopharyngeal dysfunction after supratentorial stroke: A voxel-based lesion-symptom mapping with propensity score matched case-control

BACKGROUND

Poststroke cricopharyngeal dysfunction has been reported to occur in 50% of brainstem strokes; however, cricopharyngeal dysfunction also occurs commonly in patients with supratentorial stroke. The hemispheric neuroanatomical location of this dysfunction has not been clearly identified.

AIM

We aimed to analyze the relationship between cricopharyngeal dysfunction and supratentorial lesion location in poststroke patients through this retrospective case-control voxel-based lesion-symptom mapping study.

METHODS

Cricopharyngeal dysfunction was diagnosed when the residue after swallowing (pyriform sinus) accounted for more than 25% of volume of pyriform sinus. Medical records and the video fluoroscopic swallowing studies of first-ever stroke patients who were admitted to our hospital during acute to subacute phase from 2009 to 2019 were reviewed. After propensity score matching to reduce the likelihood of selection bias, 50 patients per group were included in the cricopharyngeal dysfunction and control groups. We used a P threshold of 0.01 corrected for multiple comparisons with permutation thresholding (5000 permutations). Dichotomized diagnosis of cricopharyngeal dysfunction and the magnitude of pyriform sinus were used as dependent variables.

RESULTS

Analysis using the Liebermeister statistics indicated that lesions of the right lentiform nucleus were associated with the development of cricopharyngeal dysfunction. After adjustment for age and total lesion volume, which are known effectors for the development of dysphagia, statistically significant correlations were found between pyriform sinus and lesions of the right lentiform nucleus and anterior corona radiata beneath the right middle frontal gyrus.

CONCLUSION

Thus, our study demonstrated for the first time that damages to the right lentiform nucleus, especially globus pallidus externa, and anterior corona radiata beneath the right middle frontal gyrus are associated with the development and severity of cricopharyngeal dysfunction.

Tube feeding predictors after ischemic hemispheric stroke during hospitalization

PURPOSE

To verify the factors associated with the need of tube feeding (TF) during patients post-ischemic stroke hospitalization.

METHOD

This is a retrospective study with 70 adult post-ischemic hemispheric stroke adult patients hospitalized in the Neurology department at a tertiary public hospital in Santa Catarina, Brazil. We investigated associations between the need of a feeding tube during hospitalization and the variables age, gender, admission and discharge NIHSS and FOIS, length of hospital stay in days, presence of thrombolytic therapy, extensive stroke, hemisphere affected, prior stroke, pneumonia during hospitalization, presence of signs of laryngeal penetration and laryngotracheal aspiration and dysphagia in the first and last swallowing clinical evaluation.

RESULTS

A total of 33 participants used tube feeding. There was a significant relationship among tube feeding and the following parameters: NIHSS (p value .001), FOIS (p value .001), extensive stroke (p value .034), left hemisphere involvement (p value .035), pneumonia during hospitalization (p value .001), length of hospital stay in days (p value .001), signs of laryngotracheal penetration/aspiration (p value .001) and dysphagia in speech-language assessment (p value .001).

CONCLUSION

Tube feeding during patients hospitalization after ischemic hemispheric stroke was predicted by the severity of stroke and signs of airway permeation.Key pointsSwallowing difficulty is one of the most common post-stroke consequences.There are few studies on the characterization of post-stroke patients with tube feeding.Tube feeding after ischemic stroke predictors were severity of stroke and signs of airway permeation.

Post-stroke dysphagia: frequency, risk factors, and topographic representation: hospital-based study

Background

The frequency of dysphagia varies considerably across literature. Post-stroke dysphagia is a common cause of increased morbidity and length of hospitalization. This study aimed to estimate the frequency, risk factors of dysphagia following first-ever ischemic or hemorrhagic stroke and its neuroradiological correlation.

Methods

Two hundred fifty patients (180 ischemic and 70 hemorrhagic strokes) with first-ever stroke were recruited within 72 h of onset. Detailed history, neurological examination, and computed tomography and/or magnetic resonance were done for each patient. Severity of stroke was evaluated by the National Institutes of Health Stroke Scale (NIHSS). Swallowing function was assessed by water swallowing test (WST) and dysphagia outcome severity scale (DOSS).

Results

Ninety-eight (39.2%) of all stroke patients had dysphagia, 57 (31.7%) of ischemic group, 41 (58.6%) of hemorrhagic group. The mean age of ischemic group with dysphagia was older than ages of non-dysphagic and older than hemorrhagic stroke with dysphagia group. The mean total NIHSS was higher in dysphagic group than non-dysphagic group in both ischemic and hemorrhagic stroke. Dysphagia in ischemic group was highly associated with diabetes mellitus (DM), hypertension (HTN), and atrial fibrillation (AF). Dysphagia was commonly associated with middle cerebral artery (MCA), brainstem, and capsular infarctions as well as with intracerebral hemorrhage (ICH) with ventricular extension. Stroke severity and lesion size were the main determinant of dysphagia severity.

Conclusions

The frequency of post-stroke dysphagia is consistent with other studies. Advanced age, DM, HTN, and AF were the main risk factors. MCA, brain stem, capsular infarctions, and ICH with ventricular extension were frequently associated with dysphagia. Stroke severity and lesion size were independent predictors of dysphagia severity.

Influence of Thermal and Gustatory Stimulus in the Initiation of the Pharyngeal Swallow and Bolus Location Instroke

INTRODUCTION/OBJECTIVE

The aim of this study is to analyze the influence of sour taste and cold temperature in the initiation of the pharyngeal swallow (IPS) and bolus location at pharyngeal swallow onset in individuals after stroke.

METHODS

Cross-sectional prospective study. The study included 52 individuals with unilateral ischemic stroke. Each individual was assessed by videofluoroscopic swallowing study with 5ml of paste bolus offering four different stimuli (natural, cold, sour, and sour-cold). The individuals were divided into two groups according to the offer sequence. Group 1 (G1) - received a randomized sequence of stimuli (24 individuals), and Group 2 (G2) -the stimuli were offered in the following order: natural, cold, sour, and sour-cold(28 individuals). The IPS time and bolus location at pharyngeal swallow onset were analyzed. The bolus location at pharyngeal swallow onset was defined using six different levels.

RESULTS

Individuals in G1 did not show a significant difference in IPS time between stimuli. However, individuals in G2 presented a significantly shorter IPS time with the sour and sour-cold stimuli than with natural or cold stimuli. The bolus location at pharyngeal swallow onset did not show significant difference between stimuli in both groups. On the other hand, in the G2 it was observed higher frequency of swallowing with sour-cold stimulus at level 1 (the bolus head was located in any region between the fauces pillar and the point where the tongue crosses the inferior border of the mandible).

CONCLUSION

The sour and sour-cold stimuli influenced the IPS time when they were offered in a sequential order. Moreover, both the IPS time and bolus location at pharyngeal swallow onset were not influenced by the sour and sour cold-bolus when offered in a random sequence.

Automatic Estimation of Laryngeal Vestibule Closure Duration Using High- Resolution Cervical Auscultation Signals

Purpose

Safe swallowing requires adequate protection of the airway to prevent swallowed materials from entering the trachea or lungs (i.e., aspiration). Laryngeal vestibule closure (LVC) is the first line of defense against swallowed materials entering the airway. Absent LVC or mistimed/ shortened closure duration can lead to aspiration, adverse medical consequences, and even death. LVC mechanisms can be judged commonly through the videofluoroscopic swallowing study; however, this type of instrumentation exposes patients to radiation and is not available or acceptable to all patients. There is growing interest in noninvasive methods to assess/monitor swallow physiology. In this study, we hypothesized that our noninvasive sensor- based system, which has been shown to accurately track hyoid displacement and upper esophageal sphincter opening duration during swallowing, could predict laryngeal vestibule status, including the onset of LVC and the onset of laryngeal vestibule reopening, in real time and estimate the closure duration with a comparable degree of accuracy as trained human raters.

Method

The sensor-based system used in this study is high-resolution cervical auscultation (HRCA). Advanced machine learning techniques enable HRCA signal analysis through feature extraction and complex algorithms. A deep learning model was developed with a data set of 588 swallows from 120 patients with suspected dysphagia and further tested on 45 swallows from 16 healthy participants.

Results

The new technique achieved an overall mean accuracy of 74.90% and 75.48% for the two data sets, respectively, in distinguishing LVC status. Closure duration ratios between automated and gold-standard human judgment of LVC duration were 1.13 for the patient data set and 0.93 for the healthy participant data set.

Conclusions

This study found that HRCA signal analysis using advanced machine learning techniques can effectively predict laryngeal vestibule status (closure or opening) and further estimate LVC duration. HRCA is potentially a noninvasive tool to estimate LVC duration for diagnostic and biofeedback purposes without X-ray imaging.

Transcranial direct current stimulation (tDCS): its effect on improving dysphagia in stroke patients

Background

Transcranial direct current stimulation (tDCS) may have a potential for improving post-stroke dysphagia.

Objective

The purpose of this study was to examine the effect of tDCS on improving dysphagia in stroke patients.

Patients and methods

Forty stroke patients were divided randomly into two equal groups (the study (group A) and control groups (group B). Group A received a physical therapy program and active (tDCS), and group B received the same physical therapy program and sham (tDCS). The Dysphagia Outcome and Severity Scale (DOSS) and videofluoroscopy were performed in all patients before and after 2 weeks of the treatment program.

Results

Before treatment, there were no significant differences between the two groups for DOSS score or digital fluoroscopic findings. After treatment, there were significant differences between the study and control group for DOSS score and digital fluoroscopic findings.

Conclusion

Anodal tDCS is effective in improving dysphagia in stroke patients.

Does the right or left hemisphere involvement affect swallowing in patients with hemiplegia?

BACKGROUND

Stroke is one of the most important causes of swallowing difficulty. It is seen in one of every two patients with stroke. Although the swallowing function is controlled by both hemispheres, it is unknown which hemisphere is more dominant than another for controlling the swallowing function. However, the aspiration and pharyngeal phase dysfunction can be seen in right hemisphere involvement while oral phase dysfunction can be seen in left hemisphere involvement.

OBJECTIVE

The aim of this study was to investigate whether water swallowing performance, deep cervical flexor muscle endurance, and maximum phonation time were affected in right handed patients with hemiplegia.

STUDY DESIGN

The study was designed as a cross-sectional study.

METHODS

Patients with unilateral strokes that damaged the right (Group I: n = 37) and left (Group II: n = 20) hemispheres were included. Swallowing difficulties were evaluated with the Turkish version of the Eating Assessment Tool. The water swallowing performance was measured with the 100 ml water swallow test. The muscle endurance (ME) of deep neck flexors was measured in the chin-tuck position. The laryngeal function was measured indirectly with maximum phonation time (MPT).

RESULTS

The mean age of patients was 73.54±7.28 years in Group I and the mean age of patients was 73.15±6.94 years in Group II. There were no differences in maximum phonation time, water swallowing performance (swallow volume, capacity, and speed), and swallowing difficulty (p > 0.05). The neck flexor muscular endurance of patients with unilateral strokes that damaged the left hemisphere was better than the patients with unilateral strokes that damaged the right hemisphere (p < 0.05). There was a relationship between MPT and ME, MPT and swallowing difficulty, ME and swallowing difficulty (r:0.637, p:0.000; r:-0.465, p:0.004; r:-0.473, p:0.003 respectively) in the right hemisphere involvement patients. There was a relationship between swallowing difficulty to swallowing volume and swallowing capacity (respectively, r:-0.402 and p:0.014; r:-0.473 and p:0.003) in the patients with unilateral strokes that damaged the right hemisphere. There was no relationship between other parameters in Group I (p > 0.05). There was no relationship between all parameters in Group II (p > 0.05).

CONCLUSIONS

This study is the first study to investigate whether water swallowing performance, deep cervical flexor muscle endurance, and maximum phonation time were affected in right handed patients with unilateral strokes that damaged the right or left hemispheres. In light of the findings of the study, it was thought that swallowing should be evaluated in detail especially in hemiplegic patients with right hemisphere involvement. There is a need for studies examining the results of swallowing rehabilitation on right or left hemisphere in hemiplegic individuals.

A Retrospective Cohort Comparing Left and Right Middle Cerebral Artery Ischemic Stroke Functional Outcomes in Acute Inpatient Rehabilitation

BACKGROUND

To date, no large population studies compare left and right middle cerebral artery (MCA) strokes and corresponding patient performance in acute rehabilitation as measured by the Functional Independence Measure (FIM).

OBJECTIVE

To compare granular performance data using the six FIM subcategories between left and right MCA territory strokes. This may foster development of individualized rehabilitation programs and affect rehabilitation policy based on phenotypic variations.

DESIGN

Retrospective cohort study.

SETTING

Inpatient rehabilitation facilities, using Uniform Data System for Medical Rehabilitation data from 2015 to 2017.

PATIENTS

Individuals with MCA strokes admitted to inpatient rehabilitation facilities (n = 38 812).

MAIN OUTCOME MEASURES

Mean FIM efficiency and FIM gain within the six FIM subcategories (self-care, sphincter control, transfers, locomotion, communication, and social cognition) were compared between left and right MCA strokes. All were stratified by admission FIM severity categories (<40, 40-80, >80). The study also examined length of stay and percentage discharged to home.

RESULTS

Mean FIM efficiency was significantly higher for left MCA strokes compared to right MCA strokes. Left MCA strokes with admission FIM <40 and 40-80 had significantly higher FIM efficiencies within the majority of FIM subcategories. However, left and right MCA strokes with admission FIM > 80 did not display any significant differences. Overall, patients with left MCA strokes were discharged to home at a significantly higher percentage. Patients with left MCA strokes with admission FIM 40-80 had on average a 2-day shorter length of stay than those with right MCA strokes.

CONCLUSIONS

Overall, patients with left MCA ischemic strokes had shorter length of stays, higher FIM efficiencies, and larger FIM gains than those with right MCA strokes. These results allow clinicians to counsel patients regarding functional gains based on diagnosis and to tailor rehabilitation programs to impairments encountered in left and right MCA territories. Including laterality of stroke and admission functional status would also improve algorithms for determining reimbursement.

Cortical and Subcortical Control of Swallowing-Can We Use Information From Lesion Locations to Improve Diagnosis and Treatment for Patients With Stroke?

Purpose Swallowing is a complex process, mediated by a broad bilateral neural network that spans from the brainstem to subcortical and cortical brain structures. Although the cortex's role in swallowing was historically neglected, we now understand, especially through clinical observations and research of patients with stroke, that it substantially contributes to swallowing control. Neuroimaging techniques (e.g., magnetic resonance imaging) have helped significantly to elucidate the role of cortical and subcortical brain areas, in general, and the importance of specific areas in swallowing control in healthy individuals and patients with stroke. We will review recent discoveries in cortical and subcortical neuroimaging research studies and their generalizability across patients to discuss their potential implications and translation to dysphagia diagnosis and treatment in clinical practice. Conclusions Stroke lesion locations have been identified that are commonly associated across patients with the occurrence and recovery of dysphagia, suggesting that clinical brain scans provide useful information for improving the diagnosis and treatment of patients with stroke. However, individual differences in brain structure and function limit the generalizability of these relationships and emphasize that the extent of the motor and sensory pathology in swallowing, and how the patient recovers, also depends on a patient's individual brain constitution. The involvement of the damaged brain tissue in swallowing control before the stroke and the health of the residual, undamaged brain tissue are crucial factors that can differ between individuals.

The effect of intensified nonverbal facilitation of swallowing on dysphagia after severe acquired brain injury: A randomised controlled pilot study

BACKGROUND

There is little high-level evidence for the effect of the nonverbal facilitation of swallowing on swallowing ability in the subacute stage of rehabilitation following severe acquired brain injury (ABI).

OBJECTIVE

To pilot test a randomised controlled trial to determine the effect of an intensification of the nonverbal facilitation of swallowing on dysphagia.

METHODS

Ten patients with severe ABI and dysphagia were randomised into two groups at a highly specialised neurorehabilitation clinic.The intervention group received an intensification of the nonverbal facilitation of swallowing and the control group received basic care of the face and mouth in addition to treatment as usual for two sessions of 20 minutes per day for three weeks.Outcomes were Functional Oral Intake Scale (FOIS), Penetration Aspiration Scale (PAS), and electrophysiological swallowing specific parameters (EMBI).

RESULTS

The intensified intervention was feasible. PAS and FOIS scores improved in both groups, with no differences between groups. The swallowing specific parameters reflected clinically observed changes in swallowing.

CONCLUSIONS

PAS and FOIS are feasible instruments to measure dysphagia. It is possible and valid to measure swallowing frequency and kinematics using electromyography and bioimpedance. The definitive study should have widened inclusion criteria and optimise intervention timing to maintain patient arousal.

Swallowing apraxia in a patient with recurrent ischemic strokes: A case report

RATIONALE

Swallowing apraxia is defined as dysfunction in oral phase caused by the deficit in the coordination of tongue, lip, and chin movements, without motor weakness, sensory loss, and cognitive decline and has not been reported yet.

PATIENT CONCERNS

A 69-year-old male with personal medical history of ischemic stroke about 10 years ago newly developed right striatocapular infarction. He had a problem in the oral phase of swallowing after recurrent ischemic strokes.

DIAGNOSES

He was diagnosed as swallowing apraxia via bed side examination and videofluoroscopic swallowing study.

INTERVENTION

Videofluoroscopic swallowing study was done in this case.

OUTCOMES

Symptoms and findings of VFSS were not improved after 2 months treatment.

LESSONS

This case implies that a clinician should be alert to swallowing apraxia as a possible cause when a patient with recurrent strokes complains of oral phase dysfunction of swallowing and considers proper diagnostic option such as videofluoroscopic swallowing study.

Functional Modules of Pharyngeal Swallowing Mechanics

OBJECTIVES

The present retrospective cohort study aims to test the hypothesis that elements of swallowing mechanics including hyoid movement, laryngeal elevation, tongue base retraction, pharyngeal shortening, pharyngeal constriction, and head and neck extension can be grouped into functional modules, and that these modules are predictably altered in disease states.

METHODS

Modified barium swallow video clips of a thick and a thin liquid swallow from 40 normal patients and 10 dysphagic post-treatment oropharyngeal head-and-neck cancer (HNC) patients were used in this study. Coordinate locations of 12 anatomical landmarks mapping pharyngeal swallowing mechanics were tracked on every frame during the pharyngeal phase of each swallow using a custom-made MATLAB tool. Morphometric modularity hypothesis testing was performed on these coordinate data to characterize the modular elements of swallowing function in each cohort using MorphoJ software.

RESULTS

The elements of normal swallowing can be grouped into four functional modules including bolus propulsion, pharyngeal shortening, airway protection, and head and neck posture. Modularity in HNC patient showed an intact airway protection module but altered bolus propulsion and pharyngeal shortening modules. To cross-validate the alteration in modules, a post hoc analysis was performed, which showed significantly increased vallecular (P < .04) and piriform (P < .05) residue but no significant change in aspiration status in the HNC cohort versus controls.

CONCLUSIONS

This study suggests that while pharyngeal swallowing mechanics is highly complex, the system is organized into functional modules, and that changes in modularity impacts swallowing performance. This approach to understanding swallowing function may help the patient care team better address swallowing difficulties.

LEVEL OF EVIDENCE

2b.

Association Between Duration of Dysphagia Recovery and Lesion Location on Magnetic Resonance Imaging in Patients With Middle Cerebral Artery Infarction

OBJECTIVE

To investigate association between lesion location on magnetic resonance imaging (MRI) performed after an infarction and the duration of dysphagia in middle cerebral artery (MCA) infarction.

METHODS

A videofluoroscopic swallowing study was performed for 59 patients with dysphagia who were diagnosed as cerebral infarction of the MCA territory confirmed by brain MRI. Lesions were divided into 11 regions of interest: primary somatosensory cortex, primary motor cortex, supplementary motor cortex, anterior cingulate cortex, orbitofrontal cortex, parieto-occipital cortex, insular cortex, posterior limb of the internal capsule (PLIC), thalamus, basal ganglia (caudate nucleus), and basal ganglia (putamen). Recovery time was defined as the period from the first day of L-tube feeding to the day that rice porridge with thickening agent was prescribed. Recovery time and brain lesion patterns were compared and analyzed.

RESULTS

The mean recovery time of all patients was 26.71±16.39 days. The mean recovery time was 36.65±15.83 days in patients with PLIC lesions and 32.6±17.27 days in patients with caudate nucleus lesions. Only these two groups showed longer recovery time than the average recovery time for all patients. One-way analysis of variance for recovery time showed significant differences between patients with and without lesions in PLIC and caudate (p<0.001).

CONCLUSION

Injury to both PLIC and caudate nucleus is associated with longer recovery time from dysphagia.

Reduced tongue force and functional swallowing changes in a rat model of post stroke dysphagia

PURPOSE

Dysphagia is a common problem after stroke that is often associated with tongue weakness. However, the physiological mechanisms of post-stroke tongue muscle weakness and optimal treatments have not been established. To advance understanding of physiological mechanisms of post stroke dysphagia, we sought to validate the unilateral transient middle cerebral artery occlusion (MCAO) rat model of ischemic stroke as a translational model of post stroke dysphagia. Our goal was to establish clinically relevant measures and chronicity of functional deficits; criteria that increase the likelihood that findings will translate to the clinic. We hypothesized that MCAO would cause tongue weakness and functional swallowing changes.

METHODS

Maximum voluntary tongue forces and videofluoroscopic swallowing studies were collected in 8-week old male Sprague-Dawley rats prior to receiving either a left MCAO (N = 10) or sham (N = 10) surgery. Tongue forces and VFSS were reassessed at 1 and 8 weeks post-surgery.

RESULTS

Maximum voluntary tongue force, bolus area, and bolus speed were significantly reduced in the MCAO group at the 1 and 8-week timepoints.

CONCLUSION

Clinically relevant changes to swallowing and tongue force support the use of the MCAO rat model as a translational model of post stroke dysphagia. This model will allow for future studies to improve our understanding of the physiology contributing to these functional changes as well as the impact of therapeutic interventions on physiological targets and function.

Mapping acute lesion locations to physiological swallow impairments after stroke

Dysphagia is a common deficit after a stroke, and it is frequently associated with pneumonia, malnutrition, dehydration, and poor quality of life. It is not yet fully clear which brain regions are directly related to swallowing, and how lesions affect swallow physiology. This study aimed to assess the statistical relationship between acute stroke lesion locations and impairment of specific aspects of swallow physiology. We performed lesion symptom mapping with 68 retrospectively recruited, acute, first-ever ischemic stroke patients. Lesions were determined on diffusion weighted MRI scans. Post-stroke swallow physiology was determined using the Modified Barium Swallow Study Impairment Profile (MBSImP©™). The relationship between brain lesion location and 17 physiological aspects of swallowing were tested using voxel-based and region-based statistical associations corrected for multiple comparisons using permutation thresholding. We found that laryngeal elevation, anterior hyoid excursion, laryngeal vestibular closure, and pharyngeal residue were associated with lesioned voxels or regions of interests. All components showed distinct and overlapping lesion locations, mostly in the right hemisphere, and including cortical regions (inferior frontal gyrus, pre- and postcentral gyrus, supramarginal gyrus, angular gyrus, superior temporal gyrus, insula), subcortical regions (thalamus, amygdala) and white matter tracts (superior longitudinal fasciculus, corona radiata, internal capsule, external capsule, ansa lenticularis, lenticular fasciculus). Our findings indicate that different aspects of post-stroke swallow physiology are associated with distinct lesion locations, primarily in the right hemisphere, and primarily including sensory-motor integration areas and their corresponding white matter tracts. Future studies are needed to expand on our findings and thus, support the development of a neuroanatomical model of post-stroke swallow physiology and treatment approaches targeting the neurophysiological underpinnings of swallowing post stroke.

•

Different aspects of swallow physiology are associated with distinct stroke lesion locations.

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Sensory-motor integration areas and white matter tracts are crucial for swallow physiology.

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Mostly regions in the right and only few in the left hemisphere contribute to swallow physiology.

Differences in swallow physiology in patients with left and right hemispheric strokes

BACKGROUND

We sought to determine the impact of lesion lateralization and lesion volume on swallow impairment on group-level by comparing patients with left and right hemisphere strokes and on patient-level by analyzing patients individually.

METHODS

We performed a retrospective, observational, cross-sectional study of 46 patients with unilateral (22 left, 24 right), acute, first-ever, ischemic strokes who received a diffusion weighted MRI (DW-MRI) and modified barium swallow study (MBSS) during their acute hospital stay. We determined lesion side on the DW-MRI and measured swallow physiology using the Modified Barium Swallow Impairment Profile (MBSImP™©), Penetration-Aspiration Scale (PAS), swallow timing, distance, area, and speed measures. We performed Pearson's Chi-Square and Wilcoxon Rank-Sum tests to compare patients with left and right hemisphere strokes, and Pearson or Spearman correlation, simple logistic regression, linear, and logistic multivariable regression modeling to assess the relationship between variables.

RESULTS

At the group-level, there were no differences in MBSImP oral swallow impairment scores between patients with left and right hemisphere stroke. In adjusted analyses, patients with right hemisphere strokes showed significantly worse MBSImP pharyngeal total scores (p = 0.02), worse MBSImP component specific scores for laryngeal vestibular closure (Bonferroni adjusted alpha p ≤ 0.0029), and worse PAS scores (p = 0.03). Patients with right hemisphere strokes showed worse timing, distance, area, and speed measures. Lesion volume was significantly associated with MBSImP pharyngeal residue (p = 0.03) and pharyngeal total scores (p = 0.04). At the patient-level, 24% of patients (4 left, 7 right) showed opposite patterns of MBSImP oral and pharyngeal swallow impairment than seen at group-level.

CONCLUSION

Our study showed differences in swallow physiology between patients with right and left unilateral strokes with patients with right hemisphere strokes showing worse pharyngeal impairment. Lesion lateralization seems to be a valuable marker for the severity of swallowing impairment at the group-level but less informative at the patient-level.

Association of Brain Lesions and Videofluoroscopic Dysphagia Scale Parameters on Patients With Acute Cerebral Infarctions

Objective

To investigate the characteristics and risk factors of dysphagia using the videofluoroscopic dysphagia scale (VDS) with a videofluoroscopic swallowing study (VFSS) in patients with acute cerebral infarctions.

Methods

In this retrospective study, the baseline VFSS in 275 stroke patients was analyzed. We divided patients into 8 groups according to lesion areas commonly observed on brain magnetic resonance imaging. Dysphagia characteristics and severity were evaluated using the VDS. We also analyzed the relationship between clinical and functional parameters based on medical records and VDS scores.

Results

In comparison studies of lesions associated with swallowing dysfunction, several groups with significant differences were identified. Apraxia was more closely associated with cortical middle cerebral artery territory lesions. Vallecular and pyriform sinus residue was more common with lesions in the medulla or pons. In addition, the results for the Korean version of the Modified Barthel Index (K-MBI), a functional assessment tool, corresponded to those in the quantitative evaluation of swallowing dysfunctions.

Conclusion

A large cohort of patients with cerebral infarction was evaluated to determine the association between brain lesions and swallowing dysfunction. The results can be used to establish a specific treatment plan. In addition, the characteristic factors associated with swallowing dysfunctions were also confirmed.

Relationship Between Subcortical Hemorrhage Size and Characteristics of Dysphagia

The subcortex is an important region in terms of swallowing function that passes fibers from the swallowing center to the cortex. However, studies on the relationship between the hemorrhage size and characteristics of dysphagia were lacking. In the present study, the relationship between subcortical hemorrhage size and characteristics of dysphagia was assessed in patients with subcortical hemorrhage. This study recruited retrospectively 49 subcortical hemorrhage patients with dysphagia. The hemorrhage size was measured and the clinical dysphagia scale (CDS) was used to evaluate the severity of dysphagia. The relationship between CDS score and hemorrhage size was analyzed. Subjects were divided into 2 groups according to average hemorrhage size of the subjects. The CDS scores of the 2 groups were compared and the relationship between each CDS item and hemorrhage size was analyzed. A significant positive correlation was observed between hemorrhage size and total CDS score. Also, a significant correlation was observed when patients over 70 years of age were excluded. The total CDS score in the large hemorrhage group was significantly higher than the CDS score in the small hemorrhage group. The CDS items including tracheostomy, lip sealing, tongue protrusion, laryngeal elevation, and reflex coughing were significantly correlated with hemorrhage size. In this study, the hemorrhage size in patients with subcortical hemorrhage correlated with the severity of dysphagia. In addition, the hemorrhage size was correlated with specific CDS items. These findings should be considered when treating subcortical hemorrhage patients with dysphagia in a clinical setting.

Clinical Effects and Differences in Neural Function Connectivity Revealed by MRI in Subacute Hemispheric and Brainstem Infarction Patients With Dysphagia After Swallowing Therapy

Background: Early detection and intervention for post-stroke dysphagia could reduce the incidence of pulmonary complications and mortality. The aims of this study were to investigate the benefits of swallowing therapy in swallowing function and brain neuro-plasticity and to explore the relationship between swallowing function recovery and neuroplasticity after swallowing therapy in cerebral and brainstem stroke patients with dysphagia.

Methods: We collected 17 subacute stroke patients with dysphagia (11 cerebral stroke patients with a median age of 76 years and 6 brainstem stroke patients with a median age of 70 years). Each patient received swallowing therapies during hospitalization. For each patient, functional oral intake scale (FOIS), functional dysphagia scale (FDS) and 8-point penetration-aspiration scale (PAS) in videofluoroscopy swallowing study (VFSS), and brain functional magnetic resonance imaging (fMRI) were evaluated before and after treatment.

Results: FOIS (p = 0.003 in hemispheric group and p = 0.039 in brainstem group) and FDS (p = 0.006 in hemispheric group and p = 0.028 in brainstem group) were both significantly improved after treatment in hemispheric and brainstem stroke patients. In hemispheric stroke patients, changes in FOIS were related to changes of functional brain connectivity in the ventral default mode network (vDMN) of the precuneus in brain functional MRI (fMRI). In brainstem stroke patients, changes in FOIS were related to changes of functional brain connectivity in the left sensorimotor network (LSMN) of the left postcentral region characterized by brain fMRI.

Conclusion: Both hemispheric and brainstem stroke patients with different swallowing difficulties showed improvements after swallowing training. For these two dysphagic stroke groups with corresponding etiologies, swallowing therapy could contribute to different functional neuroplasticity.

"Hidden in Plain Sight": A Descriptive Review of Laryngeal Vestibule Closure

A major emphasis in the evaluation of swallowing is to identify physiological abnormalities in swallowing that contribute to or explain unsafe swallowing (i.e., ingested material enters the trachea; post-swallow residue in the pharynx). Impairments in laryngeal vestibule closure are widely recognized as one of the major causes of unsafe swallowing, as it is the primary mechanism and first line of defense for preventing material from penetrating the airway during swallowing. However, this complex mechanism is often overlooked and understudied in swallowing research and dysphagia management. The purpose of this review is to promote a better understanding of the mechanism of laryngeal vestibule closure. We discuss where gaps in research exist and propose future directions for incorporating laryngeal vestibule closure as a primary outcome measure in swallowing research. Additionally, we propose that an increased knowledge of the mechanism of laryngeal vestibule closure will increase diagnostic accuracy and optimize dysphagia management for patients with dysphagia.

Swallowing outcomes in patients with subcortical stroke associated with lesions of the caudate nucleus and insula

Objective The present study was performed to investigate the relationships between swallowing outcomes and lesion location, bolus characteristics, and age in patients with subcortical stroke.

PATIENTS

Patients with subcortical and insular stroke (mean age, 57.38 ± 12.71 years) were investigated. All patients (n = 21) completed both brain magnetic resonance imaging studies and videofluoroscopic swallowing studies. Main Outcome Measures The oral transit duration, pharyngeal transit duration (PTD), laryngeal response duration, and Penetration-Aspiration Scale (PAS) score were applied to examine the efficiency of propulsion and airway protection in three swallowing tasks. Path analyses were performed to assess the relationships between swallowing outcomes and lesion location, age, bolus viscosity, and bolus volume. Results Caudate nucleus (CN) lesions were associated with higher PAS scores. Insular lesions were associated with a longer PTD. Advanced age was associated with a longer PTD. Bolus viscosity significantly moderated the association between CN lesions and higher PAS scores. Conclusions In the present cohort, CN lesions impacted airway protection and insular lesions impacted pharyngeal transit. An increased bolus viscosity reduced the aspiration severity. These results suggest that lesion location is an important indicator to predict subsequent dysphagia in patients with subcortical stroke.

Neural Mechanisms of Swallowing Dysfunction and Apraxia of Speech in Acute Stroke

Speech and swallowing utilize overlapping anatomy and are thus inherently related processes. We sought to identify common neural mechanisms between risk of swallowing dysfunction and apraxia of speech (AOS). This was a retrospective analysis using data from a prospectively collected cohort. Left hemisphere stroke patients (68 subjects) tested with the Apraxia Battery for Adults II, a swallow screen, and MRI were included in the study. Main outcome measure was the presence of AOS or aspiration risk after stroke. We identified a significant association between AOS measures and increased aspiration risk (defined by failed swallow screen; p = 0.04; OR 5.2). Lesions in pars opercularis of Broca's area (BA 44) were associated with both AOS (p = 0.044; OR 9.7) and increased aspiration risk (p = 0.04; OR 5) but deficits rarely co-occurred in the same cases. Lesions in left premotor cortex (BA 6) were not significantly associated with increased aspiration risk (p = 0.06; OR 3.3) but were significantly associated with AOS (p = 0.008; OR 7). Impaired swallowing function was also associated with lesions in Wernicke's area (BA 22; p = 0.05; OR 3.5) and pars triangularis (BA 45; p = 0.02; OR 6.8). AOS and risk of aspiration are associated in patients with acute left hemisphere stroke. Acute infarct in the pars opercularis of Broca's area is associated with both deficits, though they rarely co-occur in the same individual. The co-occurrence of AOS and risk of aspiration likely reflects dependence on closely related neural structures.