Age-Related Differences in Laterality of Cortical Activations in Swallowing

Neurophysiological characterization of oropharyngeal dysphagia in older patients

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

SIGNIFICANCE

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

Day-to-Day Variability of Clinical Feeding and Swallowing Performance in School-Age Self-Feeding Children With Cerebral Palsy

PURPOSE

We aimed to examine the day-to-day variability of feeding and swallowing performance and mealtime duration in school-age self-feeding children with spastic cerebral palsy (SCP) across 15 days.

METHOD

Thirteen children with SCP (ages 5;10 [years;months]-17;6) participated. Children were divided into unilateral (UCP, n = 6) and bilateral (BCP, n = 7) SCP groups. Feeding/swallowing assessments using the Dysphagia Disorder Survey (DDS) were conducted and total mealtime durations (TMDs) were calculated for all days. DDS Part 1 (factors related to feeding) and DDS Part 2 (signs of oropharyngeal difficulties) components were rated. Mixed-effects models were used to compare group means and estimate between- and within-subject variances in each group. Likelihood ratio tests were used to determine best covariance structure and compare variance types across groups.

RESULTS

Within-subject variance for all three variables, DDS Part 1, 2, and TMD, across days was larger in the BCP group than the UCP group (Part 1: p = .0036, Part 2: p = .0002, and TMD: p = .0005) and the between-subject variance was larger in the BCP group for DDS Part 2 (p = .0362). The UCP group presented with lower (milder) DDS scores (Part 1: p = .0160; Part 2: p = .0141) and shorter TMD (p = .0077) than the BCP group across days. Furthermore, both groups exhibited greater variability in DDS Part 2 than 1 (p < .0001).

CONCLUSION

These preliminary results emphasize the need to account for day-to-day variability when evaluating swallowing especially in children with BCP and provide preliminary ranges of performance that could be useful for clinical prognosis and future treatment research.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21669611.

Hemodynamic signal changes and swallowing improvement of repetitive transcranial magnetic stimulation on stroke patients with dysphagia: A randomized controlled study

Objective

Our study aims to measure the cortical correlates of swallowing execution in patients with dysphagia after repetitive transcranial magnetic stimulation (rTMS) therapy using functional near-infrared spectroscopy (fNIRS), and observe the change of pattern of brain activation in stroke patients with dysphagia after rTMS intervention. In addition, we tried to analyze the effect of rTMS on brain activation in dysphagia patients with different lesion sides. This study also concentrated on the effect of stimulating the affected mylohyoid cortical region by 5 Hz rTMS, providing clinical evidence for rTMS therapy of dysphagia in stroke patients.

Methods

This study was a sham-controlled, single-blind, randomized controlled study with a blinded observer. A total of 49 patients completed the study, which was randomized to the rTMS group (n = 23) and sham rTMS group (n = 26) by the random number table method. The rTMS group received 5 Hz rTMS stimulation to the affected mylohyoid cortical region of the brain and the sham rTMS group underwent rTMS using the same parameters as the rTMS group, except for the position of the coil. Each patient received 2 weeks of stimulation followed by conventional swallowing therapy. Standardized Swallowing Assessment (SSA), Fiberoptic Endoscopic Dysphagia Severity Scale (FEDSS), Penetration-Aspiration Scale (PAS), and functional oral intake status were assessed at two times: baseline (before treatment) and 2 weeks (after intervention). Meanwhile, we use the fNIRS system to measure the cerebral hemodynamic changes during the experimental procedure.

Results

The rTMS group exhibited significant improvement in the SSA scale, FEDSS scale, and PAS scale after rTMS therapy (all P &lt; 0.001). The sham rTMS group had the same analysis on the same scales (all P &lt; 0.001). There was no significant difference observed in clinical assessments at 2 weeks after baseline between the rTMS group and sham rTMS group (all P &gt; 0.05). However, there were statistically significant differences between the two groups in the rate of change in the FEDSS score (P = 0.018) and PAS score (P = 0.004), except for the SSA score (P = 0.067). As for the removal rate of the feeding tube, there was no significant difference between the rTMS group and sham rTMS group (P = 0.355), but there was a significant difference compared with the baseline characteristics in both groups (PrTMS &lt; 0.001, PshamrTMS = 0.002). In fNIRS analysis, the block average result showed differences in brain areas RPFC (right prefrontal cortex) and RMC (right motor cortex) significantly between the rTMS group and sham rTMS group after intervention (Pchannel30 = 0.046, Pchannel16 = 0.006). In the subgroup analysis, rTMS group was divided into left-rTMS group and right-rTMS group and sham rTMS group was divided into sham left-rTMS group and sham right-rTMS group. The fNIRS results showed no significance in block average and block differential after intervention between the left-rTMS group and sham left-rTMS group, but differences were statistically significant between the right-rTMS group and sham right-rTMS group in block average: channel 30 (T = −2.34, P = 0.028) in LPFC (left prefrontal cortex) and 16 (T = 2.54, P = 0.018) in RMC. After intervention, there was no significance in left-rTMS group compared with baseline, but in right-rTMS group, channel 27 (T = 2.18, P = 0.039) in LPFC and 47 (T = 2.17, P = 0.039) in RPFC had significance in block differential. In the sham rTMS group, neither sham left-rTMS group and sham right-rTMS group had significant differences in block average and block differential in each brain area after intervention (P &gt; 0.05).

Conclusions

The present study confirmed that a 5-Hz rTMS is feasible at the affected mylohyoid cortical region in post-stroke patients with dysphagia and rTMS therapy can alter cortical excitability. Based on previous studies, there is a dominant hemisphere in swallowing and the results of our fNIRS analysis seemed to show a better increase in cortical activation on the right side than on the left after rTMS of the affected mylohyoid cortical region. However, there was no difference between the left and right hemispheres in the subgroup analysis. Nevertheless, the present study provides a novel and feasible method of applying fNIRS to assessment in stroke patients with dysphagia.

Clinical determinants and neural correlates of presbyphagia in community-dwelling older adults

Background

“Presbyphagia” refers to characteristic age-related changes in the complex neuromuscular swallowing mechanism. It has been hypothesized that cumulative impairments in multiple domains affect functional reserve of swallowing with age, but the multifactorial etiology and postulated compensatory strategies of the brain are incompletely understood. This study investigates presbyphagia and its neural correlates, focusing on the clinical determinants associated with adaptive neuroplasticity.

Materials and methods

64 subjects over 70 years of age free of typical diseases explaining dysphagia received comprehensive workup including flexible endoscopic evaluation of swallowing (FEES), magnetoencephalography (MEG) during swallowing and pharyngeal stimulation, volumetry of swallowing muscles, laboratory analyzes, and assessment of hand-grip-strength, nutritional status, frailty, olfaction, cognition and mental health. Neural MEG activation was compared between participants with and without presbyphagia in FEES, and associated clinical influencing factors were analyzed. Presbyphagia was defined as the presence of oropharyngeal swallowing alterations e.g., penetration, aspiration, pharyngeal residue pooling or premature bolus spillage into the piriform sinus and/or laryngeal vestibule.

Results

32 of 64 participants showed swallowing alterations, mainly characterized by pharyngeal residue, whereas the airway was rarely compromised. In the MEG analysis, participants with presbyphagia activated an increased cortical sensorimotor network during swallowing. As major clinical determinant, participants with swallowing alterations exhibited reduced pharyngeal sensation. Presbyphagia was an independent predictor of a reduced nutritional status in a linear regression model.

Conclusions

Swallowing alterations frequently occur in otherwise healthy older adults and are associated with decreased nutritional status. Increased sensorimotor cortical activation may constitute a compensation attempt to uphold swallowing function due to sensory decline. Further studies are needed to clarify whether the swallowing alterations observed can be considered physiological per se or whether the concept of presbyphagia may need to be extended to a theory with a continuous transition between presbyphagia and dysphagia.

Swallowing function in the chronic stage following stroke is associated with white matter integrity of the callosal tract between the interhemispheric S1 swallowing representation areas

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Swallowing performance was tested in dysphagic patients following stroke.

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M1 and S1 callosal tracts relevant for swallowing was mapped in the HCP-dataset.

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S1 and M1 swallowing tracts were overlapping between in house and HCP datasets.

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Swallowing specific callosal tracts showed lower FA for patients compared to HCs.

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Integrity of S1 callosal fibres (FA) was associated with swallowing performance.

Sensorimotor representations of swallowing in pre- and postcentral gyri of both cerebral hemispheres are interconnected by callosal tracts. We were interested in (1) the callosal location of fibers interconnecting the precentral gyri (with the primary motor cortex; M1) and the postcentral gyri (with the primary somatosensory cortex; S1) relevant for swallowing, and (2) the importance of their integrity given the challenges of swallowing compliance after recovery of dysphagia following stroke. We investigated 17 patients who had almost recovered from dysphagia in the chronic stage following stroke and age-matched and gender-matched healthy controls. We assessed their swallowing compliance, investigating swallowing of a predefined bolus in one swallowing movement in response to a ‘go’ signal when in a lying position. A somatotopic representation of swallowing was mapped for the pre- and postcentral gyrus, and callosal tract location between these regions was compared to results for healthy participants. We applied multi-directional diffusion-weighted imaging of the brain in patients and matched controls to calculate fractional anisotropy (FA) as a tract integrity marker for M1/S1 callosal fibers. Firstly, interconnecting callosal tract maps were well spatially separated for M1 and S1, but were overlapped for somatotopic differentiation within M1 and S1 in healthy participants’ data (HCP: head/face representation; in house dataset: fMRI-swallowing representation in healthy volunteers). Secondly, the FA for both callosal tracts, connecting M1 and S1 swallowing representations, were decreased for patients when compared to healthy volunteers. Thirdly, integrity of callosal fibers interconnecting S1 swallowing representation sites was associated with effective swallowing compliance. We conclude that somatosensory interaction between hemispheres is important for effective swallowing in the case of a demanding task undertaken by stroke survivors with good swallowing outcome from dysphagia.

Deterioration of the Corticobulbar Tract in Older Dysphagic Patients Without Neurologic Diseases

OBJECTIVES

Less is known how dysphagia affects older patients without neurologic diseases and whether the symptoms of dysphagia have any association with impaired central control of swallowing. This study investigated the state of the corticobulbar tract, the surrogate marker for the central control of swallowing, in older dysphagic patients without any neurologic diseases, using diffusion tensor tractography.

DESIGN

This retrospective observational study was conducted at a tertiary university hospital including 10 patients 60 yrs or older with oropharyngeal dysphagia without neurological disease and 11 age- and sex-matched control participants. The corticobulbar tract was reconstructed, and the fractional anisotropy and tract volume were measured using diffusion tensor tractography.

RESULTS

The corticobulbar tracts of the dysphagia group were narrowed and not reconstructed by their configurations and had lower fractional anisotropy and tract volume values when compared with those of control group. Significant asymmetry between the left and the right corticobulbar tract hemispheres was found in the dysphagia group, whereas no asymmetry was found in the control group.

CONCLUSIONS

A deteriorated corticobulbar tract could be associated with the development of dysphagia in older adults without neurological diseases. Our findings might help establish more appropriate treatment strategies, such as targeted neuromodulation therapies in the future.

Cognitive Impairment and Mild to Moderate Dysphagia in Elderly Patients: A Retrospective Controlled Study

Background: To investigate whether cognitive impairment in elderly patients could correlate with the severity of swallowing disorders detectable through the endoscopic fiber optic evaluation. Methods: Elderly patients (≥65 years) performing a swallowing evaluation were included and divided according to the Dysphagia outcome and severity scale (DOSS). Neurological evaluation and Mini-Mental test examination (MMET) were administered to detect cognitive impairment. Results: Significantly worse swallowing function was reported in the cognitive impairment group than the control one (40% vs 19%; P = .001). A different significant distribution of swallowing performance was detected according to the patient's MMET score (P < .001; P < .001; P = .01). At the ANOVA test among dependent variables assessed, only age>65 and MMET<10 were significantly correlated with swallowing function (F = 3.862, P = .028; F = 17.49, P = .000). Conclusions: The elderly patient has an increased risk for unrecognized swallowing disorders, with a prevalence of mild to moderate forms. Assessment of cognitive performance could facilitate the identification of swallowing disorders by providing a higher level of suspicion for silent aspiration in subjects with poor MMET scores.

Application of transcranial direct current stimulation in cricopharyngeal dysfunction with swallowing apraxia caused by stroke: A case report

RATIONALE

Dysphagia is a common complication after stroke. The 2 types of dysphagia with cricopharyngeal dysfunction and swallowing apraxia after stroke are relatively rare and difficult to treat; however, there are few clinical case reports of cricopharyngeal dysfunction and swallowing apraxia after stroke.

PATIENT CONCERNS

A case of cricopharyngeal dysfunction and swallowing apraxia due to cerebral infarction caused by atrial fibrillation in a 63-year-old woman who was followed up for 1 year.

DIAGNOSES

The patient was diagnosed with cricopharyngeal dysfunction and swallowing apraxia caused by stroke based on the clinical course and imaging findings.

INTERVENTIONS

Pharmacotherapy and rehabilitation therapy.

OUTCOME

The patient's swallowing function returned to normal, and her nasal feeding tubes were removed, and oral feeding was resumed.

LESSONS

The 2 types of dysphagia with cricopharyngeal dysfunction and swallowing apraxia after stroke are relatively rare and difficult to treat after stroke. Only by improving swallowing apraxia can patients perform mandatory swallowing and balloon dilatation treatment. However, transcranial direct current stimulation has a good therapeutic effect on the primary motor and sensory cortex of the tongue in patients with cricopharyngeal dysfunction and swallowing apraxia.

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.

Motor and sensory cortical processing of neural oscillatory activities revealed by human swallowing using intracranial electrodes

Swallowing is attributed to the orchestration of motor output and sensory input. We hypothesized that swallowing can illustrate differences between motor and sensory neural processing. Eight epileptic participants fitted with intracranial electrodes over the orofacial cortex were asked to swallow a water bolus. Mouth opening and swallowing were treated as motor tasks, whereas water injection was treated as a sensory task. Phase-amplitude coupling between lower-frequency and high γ (HG) bands (75–150 Hz) was investigated. An α (10–16 Hz)-HG coupling appeared before motor-related HG power increases (burst), and a θ (5–9 Hz)-HG coupling appeared during sensory-related HG bursts. The peaks of motor-related coupling were 0.6–0.7 s earlier than that of HG power. The motor-related HG was modulated at the trough of the α oscillation, and the sensory-related HG amplitude was modulated at the peak of the θ oscillation. These contrasting results can help to elucidate the brain's sensory motor functions.

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Swallowing has two aspects; sensory input and motor output

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Phase-amplitude coupling showed differences of motor and sensory neural processing

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Coupling between the α and high γ band occurred before motor-related high γ activities

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Coupling between the θ and high γ band occurred during sensory-related high γ activities

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.

A pilot study of the effects of high-frequency repetitive transcranial magnetic stimulation on dysphagia in the elderly

BACKGROUND

Swallowing difficulty is common in the geriatric population and is associated with brain activity alteration with advancing age. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive approach to stimulate cortical neurons and can produce changes in cortical excitability. The objective of this study is to determine whether rTMS induces positive changes in the cortical areas and facilitates swallowing function in the elderly diagnosed with dysphagia.

METHODS

Eight right-handed elderly dysphagia patients without any neurologic deficits received 5 Hz rTMS to a pharyngeal motor hot spot in the right hemisphere for 10 minutes every weekday for 2 weeks. The intensity of the stimulation was set at 90% of the thenar motor threshold of the same hemisphere. They were all subjected to 18F-labeled fluorodeoxyglucose-PET scans at swallowing before and after rTMS. Differences between each patient's active image and control images on a voxel-by-voxel basis were examined to find significant increases in metabolism using statistical parametric mapping software. Videofluoroscopic swallowing study was also conducted before and after magnetic stimulation intervention. Penetration-aspiration scale (PAS) and videofluoroscopic dysphagia scale (VDS) were compared to evaluate swallowing function.

KEY RESULTS

After 2 weeks of rTMS intervention, the VDS score was significantly reduced (from 43.6 ± 10.3 to 27.2 ± 14.5: P < 0.05), and especially pharyngeal motor function was improved. Activation was significantly increased in the bilateral primary motor cortex, premotor cortex, and right prefrontal cortex, which showed asymmetry.

CONCLUSIONS AND INFERENCES

High-frequency rTMS positively affected the activation in cortices and swallowing function in elderly patients with dysphagia.

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.

Novel Mealtime Duration Measures: Reliability and Preliminary Associations With Clinical Feeding and Swallowing Performance in Self-Feeding Children With Cerebral Palsy

PURPOSE

The purpose of this study is to examine (a) the reliability of newly developed measures of mealtime duration and (b) their relationship to clinical feeding/swallowing performance in children with spastic cerebral palsy (SCP).

METHOD

Seventeen self-feeding children (9 boys, 8 girls) with SCP (age range = 5;1 [years;months] to 17;6, Gross Motor Function Classification System range = I-IV) were assessed during mealtimes using the Dysphagia Disorder Survey (DDS; Sheppard, Hochman, & Baer, 2014). Children were divided into 2 groups, children with primarily unilateral or bilateral brain involvement. Duration measures included mealtime duration and total sip/bite duration for each bolus type (liquid and solid).

RESULTS

Excellent intra- and inter-rater reliability for all duration measures was observed (intraclass correlation coefficient [ICC] = 1.00 and 0.955, respectively, for mealtime duration; ICC = 1.00 and 0.963, respectively, for solid/bite duration; ICC = 1.00 and 0.957, respectively, for liquid/sip duration). Positive correlations were found between total mealtime duration and DDS Part 1, rs = .514 [.045-.797], p = .035; Part 2, rs = .528 [.064-.804], p = .029; and total scores, rs = .665 [.271-.868], p = .004, and between total solid/bite duration and DDS Part 1, rs = .579 [.137-.828], p = .015; Part 2, rs = .620 [.199-.847], p = .007; and total scores, rs = .762 [.444-.909], p < .001. Children with unilateral brain involvement exhibited significantly lower DDS total (p = .049) and Part 2 scores (p = .026), indicating better feeding/swallowing performance/skills. They also had shorter mealtime duration (p = .019) and solid/bite duration (p = .025) compared with children with bilateral involvement.

CONCLUSIONS

Our new mealtime duration measures are reliable and correlate with feeding/swallowing performance in a sample of self-feeding children with SCP. Therefore, they may be useful supplements to feeding/swallowing assessments for this population.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.5715076.

Changes of cortical activation in swallowing following high frequency repetitive transcranial magnetic stimulation in older adults

BACKGROUND

This study explored whether high-frequency repetitive transcranial magnetic stimulation (rTMS) can induce positive changes in the cortical areas of older adults who do not have functional difficulties in swallowing.

METHODS

Ten healthy, right-handed, elderly volunteers were subjected to 18F-labeled fluorodeoxyglucose positron emission tomography(FDG-PET) scans when at rest, swallowing before rTMS, and swallowing after rTMS. During the swallowing study, water was infused orally via a catheter at a rate of 600 mL/h. Subjects swallowed water every 20 seconds following a light flash for 30 minutes. During rest, the light source was active, but subjects were requested not to swallow. The rTMS consisted of 5 Hz applied to a pharyngeal motor hot spot in the right hemisphere for 10 minutes every weekday for 2 weeks. The intensity of the stimulation was set at 90% of the thenar motor threshold of the same hemisphere. The differences between each patient's active image and the control images (P<.05) on a voxel-by-voxel basis were examined to find significant increases in metabolism using statistical parametric mapping software.

KEY RESULTS

The cortical areas activated by swallowing before rTMS included the bilateral sensorimotor cortex (Brodmann's areas 3 and 4) and showed symmetry. The cortical areas activated by swallowing after rTMS were the same as the areas before rTMS. There was no statistical difference between the two swallowing activation areas.

CONCLUSIONS AND INFERENCES

Older adults displayed the symmetry of cortical control of swallowing function. High frequency rTMS did not affect the activation in the swallowing sensorimotor cortices of elderly people.

Swallowing Preparation and Execution: Insights from a Delayed-Response Functional Magnetic Resonance Imaging (fMRI) Study

The present study sought to elucidate the functional contributions of sub-regions of the swallowing neural network in swallowing preparation and swallowing motor execution. Seven healthy volunteers participated in a delayed-response, go, no-go functional magnetic resonance imaging study involving four semi-randomly ordered activation tasks: (i) "prepare to swallow," (ii) "voluntary saliva swallow," (iii) "do not prepare to swallow," and (iv) "do not swallow." Results indicated that brain activation was significantly greater during swallowing preparation, than during swallowing execution, within the rostral and intermediate anterior cingulate cortex bilaterally, premotor cortex (left > right hemisphere), pericentral cortex (left > right hemisphere), and within several subcortical nuclei including the bilateral thalamus, caudate, and putamen. In contrast, activation within the bilateral insula and the left dorsolateral pericentral cortex was significantly greater in relation to swallowing execution, compared with swallowing preparation. Still other regions, including a more inferior ventrolateral pericentral area, and adjoining Brodmann area 43 bilaterally, and the supplementary motor area, were activated in relation to both swallowing preparation and execution. These findings support the view that the preparation, and subsequent execution, of swallowing are mediated by a cascading pattern of activity within the sub-regions of the bilateral swallowing neural network.

A Longitudinal Study of Symptoms of Oropharyngeal Dysphagia in an Elderly Community-Dwelling Population

Dysphagia has been estimated to affect around 8–16 % of healthy elderly individuals living in the community. The present study investigated the stability of perceived dysphagia symptoms over a 3-year period and whether such symptoms predicted death outcomes. A population of 800 and 550 elderly community-dwelling individuals were sent the Sydney Swallow Questionnaire (SSQ) in 2009 and 2012, respectively, where an arbitrary score of 180 or more was chosen to indicate symptomatic dysphagia. The telephone interview cognitive screen measured cognitive performance and the Geriatric Depression Scale measured depression. Regression models were used to investigate associations with dysphagia symptom scores, cognition, depression, age, gender and a history of stroke; a paired t test was used to examine if individual mean scores had changed. A total of 528 participants were included in the analysis. In 2009, dysphagia was associated with age (P = 0.028, OR 1.07, CI 1.01, 1.13) and stroke (P = 0.046, OR 2.04, CI 1.01, 4.11) but these associations were no longer present in 2012. Those who had symptomatic dysphagia in 2009 (n = 75) showed a shift towards improvement in swallowing (P < 0.001, mean = −174.4, CI −243.6, −105.3), and for those who died from pneumonia, there was no association between the SSQ derived swallowing score and death (P = 0.509, OR 0.10, CI −0.41, −0.20). We conclude that swallowing symptoms are a temporally dynamic process, which increases our knowledge on swallowing in the elderly.

Functional magnetic resonance and swallowing: critical literature review

Introduction

Aspects of the neuroanatomical representation of swallowing have been investigated in humans through brain mapping techniques, such as functional magnetic resonance imaging (fMRI).

Objective

This critical qualitative review of the literature analyzed international scientific publications in the PubMed database that investigated the activation of the central nervous system in humans during the act of swallowing.

Methods

This investigation was limited to articles that investigated adults older than 18 years, published in English or Portuguese, between January 2002 and December 2013. Publications that did not have access to the full text, that were repeated by overlapping keywords, case studies, literature reviews, letters to the editor, and those not directly related to the topic of the investigation were excluded.

Results

A total of 649 articles were identified, of which 21 matched the inclusion criteria.

Conclusion

The main purpose of the manuscripts that investigate the swallowing process through fMRI were: to characterize swallowing in different pathologies; to compare swallowing in different age groups; to describe brain activation in different stimulation conditions. These studies indicate multiple cortical regions involved in swallowing control. Overall, the studies indicate that fMRI is a non-invasive and quantitative method that allows the investigation of characteristics that are quite often not clinically visible.

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

Electrophysiological assessment provides valuable information on physiological and pathophysiological characteristics of human swallowing. Here, new electrophysiological measures for the evaluation of oropharyngeal swallowing were assessed: (1) the activation pattern of the submental/suprahyoid EMG activity (SHEMG); (2) the reproducibility of the oral and pharyngeal phases of swallowing, by calculating the similarity index (SI) of the SHEMG (SI-SHEMG) and of the laryngeal-pharyngeal mechanogram (SI-LPM) during repeated swallows; and (3) kinesiological measures related to the LPM. An electrophysiological-mechanical method for measuring the activation pattern of the SHEMG, the SI-SHEMG, and the SI-LPM, and maximal LPM velocity and acceleration during swallowing was applied in 65 healthy subjects divided into three age groups (18-39, 40-59, 60 years or over). All the measures were assessed during three trials of eight consecutive swallows of different liquid bolus volumes (3, 12, and 20 ml). A high overall reproducibility of oropharyngeal swallowing in healthy humans was recorded. However, while values of SI-SHEMG were similar in all the age groups, the SI-LPM was found to fall significantly in the older age group. Both the SI-SHEMG and the SI-LPM were found to fall with increasing bolus volumes. The activation pattern of the SHEMG and the LPM kinesiological measures were differently modified by bolus volume and age in the older subjects with respect to the others. We describe a new approach to the electrophysiological study of swallowing based on computed semi-automatic analyses. Our findings provide insight into some previously uninvestigated aspects of oropharyngeal swallowing physiology, considered in relation to bolus volume and age. The new electrophysiological measures here described could prove useful in the clinical setting, as it is likely that they could be differently affected in patients with different kinds of dysphagia.

Hemodynamic Signal Changes Accompanying Execution and Imagery of Swallowing in Patients with Dysphagia: A Multiple Single-Case Near-Infrared Spectroscopy Study

In the present multiple case study, we examined hemodynamic changes in the brain in response to motor execution (ME) and motor imagery (MI) of swallowing in dysphagia patients compared to healthy matched controls using near-infrared spectroscopy (NIRS). Two stroke patients with cerebral lesions in the right hemisphere, two stroke patients with lesions in the brainstem, and two neurologically healthy control subjects actively swallowed saliva (ME) and mentally imagined to swallow saliva (MI) in a randomized order while changes in concentration of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) were assessed. In line with recent findings in healthy young adults, MI and ME of swallowing led to the strongest NIRS signal change in the inferior frontal gyrus in stroke patients as well as in healthy elderly. We found differences in the topographical distribution and time course of the hemodynamic response in dependence on lesion location. Dysphagia patients with lesions in the brainstem showed bilateral hemodynamic signal changes in the inferior frontal gyrus during active swallowing comparable to healthy controls. In contrast, dysphagia patients with cerebral lesions in the right hemisphere showed more unilateral activation patterns during swallowing. Furthermore, patients with cerebral lesions showed a prolonged time course of the hemodynamic response during MI and ME of swallowing compared to healthy controls and patients with brainstem lesions. Brain activation patterns associated with ME and MI of swallowing were largely comparable, especially for changes in deoxy-Hb. Hence, the present results provide new evidence regarding timing and topographical distribution of the hemodynamic response during ME and MI of swallowing in dysphagia patients and may have practical impact on future dysphagia treatment.

Compensatory recombination phenomena of neurological functions in central dysphagia patients

We speculate that cortical reactions evoked by swallowing activity may be abnormal in patients with central infarction with dysphagia. The present study aimed to detect functional imaging features of cerebral cortex in central dysphagia patients by using blood oxygen level-dependent functional magnetic resonance imaging techniques. The results showed that when normal controls swallowed, primary motor cortex (BA4), insula (BA13), premotor cortex (BA6/8), supramarginal gyrus (BA40), and anterior cingulate cortex (BA24/32) were activated, and that the size of the activated areas were larger in the left hemisphere compared with the right. In recurrent cerebral infarction patients with central dysphagia, BA4, BA13, BA40 and BA6/8 areas were activated, while the degree of activation in BA24/32 was decreased. Additionally, more areas were activated, including posterior cingulate cortex (BA23/31), visual association cortex (BA18/19), primary auditory cortex (BA41) and parahippocampal cortex (BA36). Somatosensory association cortex (BA7) and left cerebellum in patients with recurrent cerebral infarction with central dysphagia were also activated. Experimental findings suggest that the cerebral cortex has obvious hemisphere lateralization in response to swallowing, and patients with recurrent cerebral infarction with central dysphagia show compensatory recombination phenomena of neurological functions. In rehabilitative treatment, using the favorite food of patients can stimulate swallowing through visual, auditory, and other nerve conduction pathways, thus promoting compensatory recombination of the central cortex functions.

Neural representation of swallowing is retained with age. A functional neuroimaging study validated by classical and Bayesian inference

We investigated the neural representation of swallowing in two age groups for a total of 51 healthy participants (seniors: average age 64 years; young adults: average age 24 years) using high spatial resolution functional magnetic resonance imaging (fMRI). Two statistical comparisons (classical and Bayesian inference) revealed no significant differences between subject groups, apart from higher cortical activation for the seniors in the frontal pole 1 of Brodmann's Area 10 using Bayesian inference. Seniors vs. young participants showed longer reaction times and higher skin conductance response (SCR) during swallowing. We found a positive association of SCR and fMRI-activation only among seniors in areas processing sensorimotor performance, arousal and emotional perception. The results indicate that the highly automated swallowing network retains its functionality with age. However, seniors with higher SCR during swallowing appear to also engage areas involved in attention control and emotional regulation, possibly suggesting increased attention and emotional demands during task performance.

Relationship between dysphagia and mild cognitive impairment in a community-based elderly cohort: the Korean longitudinal study on health and aging

OBJECTIVES

To investigate the relationship between dysphagia and mild cognitive impairment (MCI) in older adults residing in an independent-living facility in Korea.

DESIGN

Population-based, cross-sectional study.

SETTING

Seongnam, Korea.

PARTICIPANTS

Korean men and women aged 65 and older living in a typical South Korean city (n = 415) were enrolled in the Korean Longitudinal Study on Health and Aging.

MEASUREMENTS

Dysphagia was assessed using the Standardized Swallowing Assessment (SSA). Cognitive function was evaluated using the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Assessment Battery, digit span test, and lexical fluency test. MCI was diagnosed using operational diagnostic criteria and further classified into amnestic and nonamnestic MCI.

RESULTS

Men with nonanmestic MCI had a greater likelihood of having dysphagia (odds ratio (OR) = 3.77, 95% confidence interval (CI) = 1.12-12.72) than men without MCI. Men with nonanmestic MCI were almost six times as likely to have dysphagia (OR = 5.78, 95% CI = 1.15-29.27) as men with no neurological disorder after adjusting for age, education level, current smoking and drinking, diabetes mellitus, and apolipoprotein E-4 carrier status.

CONCLUSION

Men with nonamnestic MCI were more likely to have dysphagia than were their counterparts without MCI, whereas this difference was not found in men with amnestic MCI and women. Assessment of executive functions that interfere with planning of motor activities may be useful in predicting dysphagia and in planning preventive and therapeutic strategies for older men.

Sequential evolution of cortical activity and effective connectivity of swallowing using fMRI

Swallowing consists of a hierarchical sequence of primary motor and somatosensory processes. The temporal interplay of different phases is complex and clinical disturbances frequent. Of interest was the temporal interaction of the swallowing network. Time resolution optimized functional magnetic resonance imaging was used to describe the temporal sequence of representation sites of swallowing and their functional connectivity. Sixteen young healthy volunteers were investigated who swallowed 2 ml of water 20 times per run with a repetition time for functional imaging of 514 ms. After applying the general linear model approach to identify activation magnitude in preselected regions of interest repeated measures analysis of variance (rmANOVA) was used to detect relevant effects on lateralization, time, and onset. Furthermore, dynamic causal modeling (DCM) was applied to uncover where the input enters the model and the way in which the cortical regions are connected. The temporal analysis revealed a successive activation starting at the premotor cortex, supplementary motor area (SMA), and bilateral thalamus, followed by the primary sensorimotor cortex, the posterior insula, and cerebellum and culminating with activation in the pons shortly before subsiding. The rmANOVA revealed that activation was lateralized initially to the left hemisphere and gradually moved to the right hemisphere over time. The group random effects DCM analysis resulted in a most likely model that consisted of inputs to SMA and M1S1, bidirectionally connected, and a one-way connection from M1S1 to the posterior insula.

Differential psychophysiological interactions of insular subdivisions during varied oropharyngeal swallowing tasks

Abstract The insula is a highly integrated cortical region both anatomically and functionally. It has been shown to have cognitive, social-emotional, gustatory, and sensorimotor functions. Insular involvement in both normal and abnormal swallowing behavior is well established, yet its functional connectivity is unclear. Studies of context-dependent connectivity, or the connectivity during different task conditions, have the potential to reveal information about synaptic function of the insula. The goal of this study was to examine the functional connectivity of specific insular regions (ventral anterior, dorsal anterior, and posterior) with distant cortical regions during four swallowing conditions (water, sour, e-stim, and visual biofeedback) using generalized psychophysiological interactions (gPPI). In 19 healthy adults, we found that the visual biofeedback condition was associated with the most and strongest increases in functional connectivity. The posterior insula/rolandic operculum regions had the largest clusters of increases in functional connectivity, but the ventral anterior insula was functionally connected to a more diverse array of cortical regions. Also, laterality assessments showed left lateralized increases in swallowing functional connectivity. Our results are aligned with reports about the insula's interconnectivity and extensive involvement in multisensory and cognitive tasks.

Physiology of the ageing gut

PURPOSE OF REVIEW

This article will review the recent publications (over the last 1-2 years) concerning the effects of ageing on gastrointestinal function, with an emphasis on the motor and sensory function of the gut.

RECENT FINDINGS

Recent publications support earlier observations of an age-related selective decline in the number of cholinergic neurons in the enteric nervous system, but also reveal a progressive loss of interstitial cells of Cajal in the stomach and colon throughout adult life. These changes appear to have surprisingly little effect on gastrointestinal motor function in healthy ageing, although gut sensation is impaired and older individuals have an increased susceptibility to gastrointestinal complications of comorbid illnesses.

SUMMARY

Alterations in gut function with ageing have particular implications in the oesophagus, colon, and anorectum. Dysphagia, gastro-oesophageal reflux disease, constipation, and faecal incontinence are the most prevalent clinical manifestations. Older individuals are also susceptible to postprandial hypotension, in which altered cardiovascular responses to intestinal nutrient exposure are pivotal. Dysphagia, delayed gastric emptying, and constipation are increasingly being recognized as early features of Parkinson's disease, and frequently precede the neurological manifestations.

Swallowing intentional off-state in aging and Alzheimer's disease: preliminary study

Frontal cortical activation is elicited when subjects have been instructed not to initiate a sensorimotor task. The goal of this preliminary fMRI study was to examine BOLD response to a "Do Not Swallow" instruction (an intentional "off-state") in the context of other swallowing tasks in 3 groups of participants (healthy young, healthy old, and early Alzheimer's disease (AD)). Overall, the older group had larger, bilaterally active clusters in the cortex, including the dorsomedial prefrontal cortex during the intentional swallowing off-state; this region is commonly active in response inhibition studies. Disease-related differences were evident where the AD group had significantly greater BOLD response in the insula/operculum than the old. These findings have significant clinical implications for control of swallowing across the age span and in neurodegenerative disease. Greater activation in the insula/operculum for the AD group supports previous studies where this region is associated with initiating swallowing. The AD group may have required more effort to "turn off" swallowing centers to reach the intentional swallowing off-state.

Functional MRI of swallowing: from neurophysiology to neuroplasticity

Swallowing is a complex neurogenic sensorimotor process involving all levels of the neuraxis and a vast number of muscles and anatomic structures. Disruption of any of these anatomic or functional components can lead to swallowing disorders (also known as dysphagia). Understanding the neural pathways that govern swallowing is necessary in diagnosing and treating patients with dysphagia. Functional MRI (fMRI) is a prevalent and effective neuroimaging method that has been used to study the complex neurophysiologic control of swallowing in vivo. This article presents a summary of the research studies that have used fMRI to study the neural control of swallowing in normal subjects and dysphagic patients, and to investigate the effects of swallowing treatments on neuroplasticity. Methodologic challenges and caveats are discussed, and a case study of a pre-posttreatment paradigm is presented to highlight potential future directions of fMRI applications in swallowing research and clinical practice.

Reduced somatosensory activations in swallowing with age

Understanding the neural functional organization of swallowing in healthy elders is essential in diagnosing and treating older adults with swallowing difficulties. The primary aims of this investigation were to identify the neural activation sites of different components of deglutition in healthy elders using functional Magnetic Resonance Imaging (fMRI) and to investigate age differences in the neural control of swallowing. Ten young (age range 19-25 years of age) and nine older (age range 66-77 years of age) right-handed healthy individuals were scanned in a 3-Tesla MRI scanner. Subjects were visually cued for both a "Swallow" task and for component/control tasks ("Prepare to swallow," "Tap your tongue," and "Clear your throat"). Behavioral interleaved gradient (BIG) methodology was used to address movement related artifacts. Between-group comparisons revealed statistically stronger activations in the primary somatosensory cortex of young adults during the motor tasks examined. Both groups showed activations in the major motor areas involved in the initiation and execution of movement; however, areas involved in sensory processing, sensorimotor integration and/or motor coordination and control, showed reduced or limited activity in the elderly. Potential implications of these findings for clinical practice are discussed.

Functional MRI of tongue motor tasks in patients with tongue cancer: observations before and after partial glossectomy

INTRODUCTION

The current study seeks to provide preliminary data regarding this central, adaptive response during tongue motor tasks utilizing functional magnetic resonance imaging (fMRI) before and after glossectomy.

METHODS

Six patients, with confirmed histological diagnoses of oral tongue cancer, underwent fMRI before and 6 months after partial glossectomy. These data were compared to nine healthy controls. All subjects performed three tongue motor tasks during fMRI: tongue tapping (TT), dry swallow (Dry), and wet swallow (Wet).

RESULTS

Following surgery, increased activation was subjectively observed in the superior parietal lobule, supplementary motor area, and anterior cingulate. Region of interest (ROI) analysis of the precentral gyrus confirmed increased cortical activity following surgery. In addition, comparisons between pre-surgical scans and controls suggested the dry swallow task was sensitive to elicit tongue-related activation in the precentral gyrus (p ≤ 0.05).

CONCLUSIONS

The adaptive changes in the cortex following partial glossectomy reflect recruitment of the parietal, frontal, and cingulate cortex during tongue motor tasks. In addition, post-operative activation patterns more closely approximated control levels than the pre-operative scans. Furthermore, the dry swallow task appears most specific to elicit tongue-related cortical activity.