Periventricular white matter changes and oropharyngeal swallowing in normal individuals

Aberrant dynamic functional network connectivity in progressive supranuclear palsy

BACKGROUND

The clinical symptoms of progressive supranuclear palsy (PSP) may be mediated by aberrant dynamic functional network connectivity (dFNC). While earlier research has found altered functional network connections in PSP patients, the majority of those studies have concentrated on static functional connectivity. Nevertheless, in this study, we sought to evaluate the modifications in dynamic characteristics and establish the correlation between these disease-related changes and clinical variables.

METHODS

In our study, we conducted a study on 53 PSP patients and 65 normal controls. Initially, we employed a group independent component analysis (ICA) to derive resting-state networks (RSNs), while employing a sliding window correlation approach to produce dFNC matrices. The K-means algorithm was used to cluster these matrices into distinct dynamic states, and then state analysis was subsequently employed to analyze the dFNC and temporal metrics between the two groups. Finally, we made a correlation analysis.

RESULTS

PSP patients showed increased connectivity strength between medulla oblongata (MO) and visual network (VN) /cerebellum network (CBN) and decreased connections were found between default mode network (DMN) and VN/CBN, subcortical cortex network (SCN) and CBN. In addition, PSP patients spend less fraction time and shorter dwell time in a diffused state, especially the MO and SCN. Finally, the fraction time and mean dwell time in the distributed connectivity state (state 2) is negatively correlated with duration, bulbar and oculomotor symptoms.

DISCUSSION

Our findings were that the altered connectivity was mostly concentrated in the CBN and MO. In addition, PSP patients had different temporal dynamics, which were associated with bulbar and oculomotor symptoms in PSPRS. It suggest that variations in dynamic functional network connectivity properties may represent an essential neurological mechanism in PSP.

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 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.

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 Relationship Between Leukoaraiosis Involving Contralateral Corticobulbar Tract and Dysphagia in Patients with Acute Unilateral Corona Radiata Infarction with Corticobulbar Tract Involvement

This study investigated the impact of leukoaraiosis (LA) involving the contralateral corticobulbar tract (CBT) on dysphagia in patients with unilateral corona radiata (CR) infarction with CBT involvement. Patients admitted to the Department of Neurology (September 2011-August 2014) were evaluated; those with a first episode of acute unilateral CR infarction involving the CBT and with LA were included. The 'Case' group comprised patients with LA involving the contralateral CBT; the 'Control' group comprised patients with LA not involving the contralateral CBT. The primary outcome was the feeding method at discharge; secondary outcomes were the feeding method at admission and results of the bedside swallowing test, videofluoroscopic swallowing study (VFSS), videofluoroscopic dysphagia scale, penetration-aspiration scale, American Speech-Language-Hearing Association National Outcome Measurement System Swallowing Scale (ASHA NOMS), oral transit time, and pharyngeal transit time. Infarct size was measured using brain magnetic resonance imaging; LA severity was rated using the Fazekas scale. Eighty-one patients were included (mean age 64.6 ± 11.5 years; 64% male; Case group: 20, 5 underwent VFSS; Control group: 67, 11 underwent VFSS). The Case group was older and had higher total Fazekas scale score than the Control group. The feeding method at discharge and ASHA NOMS score were significantly worse in the Case group than in the Control group. Multivariate analysis revealed that LA involving the contralateral CBT independently predicted the feeding method at discharge and ASHA NOMS score. In conclusion, LA involving the contralateral CBT is associated with dysphagia in patients with unilateral CR infarction involving the CBT.

Is the Location of White Matter Lesions Important in the Swallowing Function of Older Patients with Mild Stroke?

Older patients with stroke have poor functional prognosis compared to younger patients. Patients with stroke who have severe white matter (WM) lesions have been reported to have swallowing problems. The aim of this study was to determine whether the location of WM lesions affects swallowing function in older patients with mild stroke. We conducted a retrospective analysis of 88 patients aged > 65 years who had a National Institutes of Health Stroke Scale score  of ≤ 5 and who underwent videofluoroscopic swallowing examination after their first stroke. Participants were divided into three groups according to the involvement of corticobulbar tract (CBT) as follows: group I, no involvement of CBT; group II, involvement of CBT in one hemisphere; and group III, involvement of CBT in both hemispheres. Linear regression analysis showed that pharyngeal transit time tended to increase according to the involvement of CBT in WM lesion (p = 0.043). In addition, inadequate laryngeal elevation was related to the involvement of CBT (p = 0.016). Early spillage, inadequate laryngeal elevation, and penetration could also be predicted by Fazekas grade. Accordingly, the location of WM lesions can be regarded as a potential predictive factor for dysphagia. Moreover, in patients with WM lesions involving CBT, detailed evaluation of dysphagia is required.

Periventricular White Matter Lesions as a Prognostic Factor of Swallowing Function in Older Patients with Mild Stroke

Older patients with stroke have poor functional prognosis compared to younger patients. Patients with stroke who have severe white matter (WM) lesions have been reported to have poor functional prognosis such as cognitive dysfunction, increased propensity for falling, and gait and balance problems. The aim of this study was to determine whether WM lesions exert negative effects on swallowing function in older patients with mild stroke. We conducted a retrospective analysis of 63 patients aged >65 years who had a National Institutes of Health Stroke Scale score ≤5 and who underwent videofluoroscopic swallowing examination after their first stroke. Linear regression analysis showed that oral transit time tended to increase as Fazekas grade increased (p = 0.003). In addition, inadequate mastication was related to the presence of lesions in the left hemisphere (p = 0.039). The presence of penetration could also be predicted by Fazekas grade (p = 0.015). Our findings suggest that WM lesions observed in brain magnetic resonance imaging scans can impact swallowing problems in older patients with mild stroke, regardless of initial stroke severity or other factors associated with lesion location. Accordingly, our data indicate that WM lesions are a predictive factor by which patients can be stratified into favorable or unfavorable outcomes with respect to dysphagia.

Leukoaraiosis is associated with pneumonia after acute ischemic stroke

Background

Stroke-associated pneumonia (SAP) is common in patients with acute ischemic stroke, and several risk factors have been reported. However, the relationship between underlying leukoaraiosis (LA) and SAP has not been addressed.

Methods

We collected consecutive patients with acute ischemic stroke within 24 h of symptom onset. SAP was defined as the lower respiratory tract infection within the first 7 days after stroke onset, according to the modified Centers for Disease Control and Prevention criteria. LA was graded using the Fazekas scale in both the periventricular and subcortical areas. We evaluated LA burden by summing the grade and dichotomized into mild LA (0–2) or severe LA (3–6). Relationship between LA and SAP was analyzed by binary logistic regression analysis with variables of P < 0.05 in univariate analysis.

Results

Three hundred eight consecutive patients were enrolled, and SAP developed in 44 patients (14%). Univariate analysis revealed that SAP correlated with age, initial NIHSS score, atrial fibrillation, impaired consciousness, dysphagia, severe LA and hyperlipidemia. On multivariate analysis, severe LA [adjusted OR (aOR) = 4.41, 95% CI = 2.04–9.55, P < 0.001 remained independent predictors of SAP after adjusted confounders.

Conclusions

In this study, LA was an independent predictor of SAP. This observation needs to be confirmed in suitably-designed, prospective studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-017-0830-5) contains supplementary material, which is available to authorized users.

Bulbar dysfunction in normal pressure hydrocephalus: a prospective study

OBJECTIVE Normal pressure hydrocephalus (NPH) is clinically characterized by gait disturbance, cognitive impairment, and urinary incontinence, as well as enlargement of the ventricles. To the best of the authors' knowledge, there have been no previous publications regarding the correlation between bulbar dysfunction and NPH. The primary objective of this study was to compare preoperative and postoperative prevalence of bulbar dysfunction in patients with NPH. Secondary objectives included assessing the results of surgery for swallowing, speech, gait, cognition, and urination, and evaluating the correlation between bulbar dysfunction and triad symptoms. METHODS Fifty-three patients with NPH who underwent shunt placement surgery at Siriraj Hospital were included in the study. Patients were evaluated for gait, cognition, urination, swallowing, and speech before and 6 months after shunt placement. Triad symptoms were assessed using standard methods. Bulbar dysfunctions were assessed using the Swallowing Problem Questionnaire, Thai Articulation Test, Resonation Screening Test (RST), and Thai Nasality Test. The Thai Speech Assessment Program and nasometer were used for objective speech measurement. RESULTS Preoperatively, 86% (43/50) of patients had swallowing problems and 75% (37/49) had speech problems, as measured by the RST. Postoperatively, there was significant improvement in swallowing (p < 0.001), speech problems by RST (p = 0.008), and voice volume (p = 0.009), but no significant change in the nasometer test. All triad symptoms were improved. There were significant correlations between swallowing impairment and gait disturbance (r = 0.358, p = 0.009), and RST and cognitive impairment (r = -0.502, p < 0.001). CONCLUSIONS This is the first study of bulbar dysfunction in patients with NPH. The results showed that the prevalence of bulbar dysfunction is very high. The correlation between bulbar dysfunction and the classic NPH triad has been documented and published. These bulbar symptoms also significantly improved after surgery. As such, bulbar dysfunction should be regarded as a core symptom that should be considered along with the classic triad in the clinical diagnosis and management of NPH.

Oropharyngeal dysphagia in older persons - from pathophysiology to adequate intervention: a review and summary of an international expert meeting

Oropharyngeal dysphagia (OD) is a highly prevalent and growing condition in the older population. Although OD may cause very severe complications, it is often not detected, explored, and treated. Older patients are frequently unaware of their swallowing dysfunction which is one of the reasons why the consequences of OD, ie, aspiration, dehydration, and malnutrition, are regularly not attributed to dysphagia. Older patients are particularly vulnerable to dysphagia because multiple age-related changes increase the risk of dysphagia. Physicians in charge of older patients should be aware that malnutrition, dehydration, and pneumonia are frequently caused by (unrecognized) dysphagia. The diagnosis is particularly difficult in the case of silent aspiration. In addition to numerous screening tools, videofluoroscopy was the traditional gold standard of diagnosing OD. Recently, the fiberoptic endoscopic evaluation of swallowing is increasingly utilized because it has several advantages. Besides making a diagnosis, fiberoptic endoscopic evaluation of swallowing is applied to evaluate the effectiveness of therapeutic maneuvers and texture modification of food and liquids. In addition to swallowing training and nutritional interventions, newer rehabilitation approaches of stimulation techniques are showing promise and may significantly impact future treatment strategies.

The relationship of leukoaraiosis and the clinical severity of vascular Parkinsonism

Vascular Parkinsonism (VP) is referred to as secondary Parkinsonian syndrome. It occurs with lacunar state or sub-cortical white matter micro-angiopathy and is highly associated with vascular risk factors and leukoaraiosis, also known as cerebral white matter lesions (WML). This study aimed to assess the prevalence of different vascular risk factors and WML in patients with VP, and their impact on clinical features. Sixty-two consecutive VP patients (70.2 ± 9.2 years) were evaluated for clinical severity using the Unified Parkinson's Disease Rating Scale (UPDRS). WML was assessed and scored on fluid-attenuated inversion recovery T2-weighted (FLAIR) magnetic resonance imaging (MRI). Cerebro-vascular risk factors, WML severity, and the UPDRS for clinical disability were analyzed statistically. There were no associations between WML score and age, sex, hypertension, diabetes, previous stroke, cardiac disease, cigarette smoking, or serum levels of cholesterol and triglyceride. The WML score positively correlated with UPDRS part I (p = 0.035) and part III (p = 0.041) scores. After adjustments for age, gender, stroke history, and use of levodopa, the WML score was associated with the UPDRS total (p = 0.020), part I (p = 0.012), part II (p = 0.039), and part III (p = 0.019) scores. The severity of WML is not associated with conventional vascular risk factors in VP patients but is significantly correlated with the UPDRS total and all sub-scores, which suggests that disruption of the cortico-sub-cortical circuits may lead to impaired mentation, behavior and mood, activities of daily living, and motor performance in these patients.

Severe brain atrophy in the elderly as a risk factor for lower respiratory tract infection

BACKGROUND

The purpose of this study is to determine whether elderly subjects with severe brain atrophy, which is associated with neurodegeneration and difficulty swallowing (dysphagia), are more susceptible to lower respiratory tract infections (LRTI), including pneumonia.

METHODS

The severity of brain atrophy was assessed by computed tomography in 51 nursing home residents aged 60-96 years. The incidence of LRTI, defined by body temperature ≥ 38.0°C, presence of two or more respiratory symptoms, and use of antibiotics, was determined over 4 years. The incidence of LRTI was compared according to the severity and type of brain atrophy.

RESULTS

The incidence rate ratio of LRTI was significantly higher (odds ratio 4.60, 95% confidence interval 1.18-17.93, fully adjusted P = 0.028) and the time to the first episode of LRTI was significantly shorter (log-rank test, P = 0.019) in subjects with severe brain atrophy in any lobe. Frontal and parietal lobe atrophy was associated with a significantly increased risk of LRTI, while temporal lobe atrophy, ventricular dilatation, and diffuse white matter lesions did not influence the risk of LRTI.

CONCLUSION

Elderly subjects with severe brain atrophy are more susceptible to LRTI, possibly as a result of neurodegeneration causing dysphagia and silent aspiration. Assessing the severity of brain atrophy might be useful to identify subjects at increased risk of respiratory infections in a prospective manner.

Upper aerodigestive tract neurofunctional mechanisms: lifelong evolution and exercise

The transformation of the upper aerodigestive tract--oral cavity, pharynx, and larynx--serves the functions of eating, speaking, and breathing during sleeping and waking hours. These life-sustaining functions may be produced by a central neural sensorimotor system that shares certain neuroanatomic networks while maintaining separate neural functional systems and network structures. Current understanding of development, maturation, underlying neural correlates, and integrative factors are discussed in light of currently available imaging modalities and recently emerging interventions. Exercise and an array of additional treatments together seem to provide promising translational pathways for evidence-based innovation, novel habilitation, and rehabilitation strategies and delay, or even prevent neuromuscular decline cross-cutting functions and supporting quality of life throughout increasingly enduring lifespans.

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.

The relationship of aspiration status with tongue and handgrip strength in healthy older adults

BACKGROUND

Recently, subclinical aspiration has been identified in approximately 30% of community-dwelling older adults. Given that the tongue is a key component of the safe swallow, we hypothesized healthy older adults who aspirate will generate less tongue strength than adults who do not aspirate. Furthermore, as muscle weakness may reflect a global effect of aging, we further investigated whether tongue strength is correlated with handgrip strength.

METHODS

We assessed 78 healthy community-dwelling older adults (M = 77.3 years, SD = 7.26) for aspiration status (37% aspirators) via flexible endoscopic evaluation of swallowing. Maximal isometric anterior and posterior tongue strength, anterior and posterior swallowing tongue strength, and maximum handgrip strength were measured.

RESULTS

Isometric tongue strength was significantly lower in aspirators versus nonaspirators (p = .03) at both the anterior (463 vs 548 mmHg, respectively) and posterior lingual locations (285 vs 370 mmHg, respectively). Likewise, swallowing tongue strength was significantly lower in aspirators versus nonaspirators at both the anterior (270 vs 317 mmHg, respectively) and posterior lingual locations (220 vs 267 mmHg, respectively). There was no difference between aspirators and nonaspirators' handgrip strength (p > .05), although handgrip strength was correlated with posterior tongue strength (r = .34, p = .005).

CONCLUSIONS

Lower anterior and posterior isometric and swallowing tongue strength were dependent on aspiration status. Lower lingual strength in healthy adults may predispose them to aspiration. The correlation between tongue and handgrip strength is consistent with the hypothesis that impaired oropharyngeal strength reflects global age-related declines in muscle strength.

Effects of dining on tongue endurance and swallowing-related outcomes

PURPOSE

The purpose of this study was to test the hypothesis that eating a meal reduces tongue strength and endurance in healthy old and young adults. It was predicted that older adults would show greater declines in tongue endurance while demonstrating higher perceived effort, longer meal durations, and clinical signs of swallowing difficulty.

METHOD

Twenty-two healthy adults were enrolled into 2 groups (ages 20-35 years and ages 65-82 years; 5 males and 6 females each). Maximum tongue strength (Pmax) and endurance (duration 50% of Pmax could be maintained) were measured twice at baseline and once postmeal. Subjects consumed half of a bagel with peanut butter, carrot sticks, and milk between measures.

RESULTS

All subjects demonstrated reduced tongue strength and endurance postmeal. Young adults showed a greater decline in anterior tongue endurance compared with older adults (p=.05). There was no evidence that changes in tongue strength, perceived effort, or meal duration varied by age or gender. The 3 oldest subjects reported the highest effort and displayed signs of difficulty swallowing while dining.

CONCLUSIONS

Young and old adults demonstrated reduced tongue strength and endurance after dining, but younger subjects showed greater declines in anterior tongue endurance, whereas older adults exhibited signs of swallowing difficulty.

Comparison of sequential swallowing in patients with acute stroke and healthy adults

OBJECTIVES

To compare hyolaryngeal complex (HLC) movement and leading-edge-of-the-bolus location patterns of sequential swallowing in patients with stroke and healthy adults, and to determine whether these patterns affect swallowing safety.

DESIGN

Between-groups comparison.

SETTING

Veterans hospital.

PARTICIPANTS

Consecutively admitted patients with acute unilateral supratentorial stroke (right hemisphere damage, n=13; left hemisphere damage, n=16) and age-matched healthy participants (n=25).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

HLC movement pattern, bolus location, Penetration-Aspiration (P-A) Scale score.

RESULTS

No significant group differences were observed for HLC movement pattern, bolus location, and P-A Scale score. Specific HLC movement patterns and bolus location were not associated with a higher P-A Scale score. A significant correlation between HLC movement pattern and bolus location was observed. Bolus location was typically inferior to the valleculae between swallows when the HLC was partially elevated. Across all groups, P-A Scale scores were significantly higher during sequential swallowing than single swallows.

CONCLUSIONS

HLC movement pattern and bolus location do not appear related to airway invasion, at least in persons without significant dysphagia. Given higher P-A Scale scores during sequential swallowing as compared with single swallows, sequential swallowing should always be evaluated in all patients.

Oropharyngeal dysphagia

Although the aging process per se can produce measurable changes in the normal oropharyngeal swallow, these changes alone are rarely sufficient to cause clinically apparent dysphagia. The causes of oropharyngeal dysphagia in the elderly are predominantly neuromyogenic, with the most common cause being stroke. The evaluation of oropharyngeal dysphagia in the elderly involves early exclusion of structural abnormalities, detection of aspiration by videofluoroscopy which might dictate early introduction of nonoral feeding, and exclusion of underlying systemic and neuromyogenic causes that have specific therapies in their own right. Such conditions include Parkinson disease, myositis, myasthenia, and thyrotoxicosis. Management is best delivered by a multidisciplinary team involving physician, speech pathologist, nutritionist and, at times, a surgeon.

Defining and measuring dysphagia following stroke

PURPOSE

To continue the development of a quantified, standard method to differentiate individuals with stroke and dysphagia from individuals without dysphagia.

METHOD

Videofluoroscopic swallowing studies (VFSS) were completed on a group of participants with acute stroke (n = 42) and healthy age-matched individuals (n = 25). Calibrated liquid volumes of 3, 5, 10, and 20 ml were administered during the VFSS. Six measures in 3 domains of bolus flow (timing, direction, and clearance) were measured. Values of these measures obtained from the control group were used to classify dysphagia within the participants.

RESULTS

The use of a single measure or single liquid volumes to classify dysphagia did not distinguish between healthy adults and individuals following stroke with and without dysphagia. Abnormality on more than 1 measure across multiple volumes appears to be a more robust method in defining dysphagia for liquids.

CONCLUSIONS

Our findings indicate that the definition of dysphagia is critical in determining whether persons are classified with disordered swallowing. The definition is dependent on materials and measures evaluated. Each measure provides independent aspects to the evaluation. Determining the level of importance of each depends on the purpose of the evaluation.

Swallow-related cerebral cortical activity maps are not specific to deglutition

Cortical representation of swallow-related motor tasks has not been systematically investigated. In this study, we elucidated and compared these cortical representations to those of volitional swallow using block-trial and single-trial methods. Fourteen volunteers were studied by functional magnetic resonance imaging. Cortical activation during both swallowing and swallow-related motor tasks that can be performed independent of swallowing, such as jaw clenching, lip pursing, and tongue rolling, was found in four general areas: the anterior cingulate, motor/premotor cortex, insula, and occipital/parietal region corresponding to Brodmann's areas 7, 19, and 31. Regions of activity, volume of activated voxels, and increases in signal intensity were found to be similar between volitional swallow and swallow-related motor tasks. These findings, using both block-trial and single-trial techniques, suggest that cerebral cortical regions activated during swallowing may not be specific to deglutitive function.

Age effects on the temporal evolution of isometric and swallowing pressure

BACKGROUND

The tongue plays a key role in bolus propulsion through the oropharyngeal chamber. In this study, possible age effects on the magnitude and timing of lingual pressure generation were analyzed.

METHODS

Oral pressure was measured during isometric and swallowing tasks for 10 elderly (mean age = 81 years) and 10 young (mean age = 51 years) subjects. Three trials each of the isometric task and swallows of three different boluses (3 ml semisolid, 3 ml liquid, and 10 ml liquid) were performed by each subject. The timing and magnitude of isometric and swallowing pressure generation along with the pattern of the swallowing pressure waveform were analyzed.

RESULTS

Whereas maximum lingual isometric pressures decreased with age (p < .001). no significant age difference was found for swallowing pressure. Time taken to reach peak pressure also was reduced with age in both the isometric task and swallows of liquid boluses (p < .05), while no significant age effect was found for semisolid swallows. Finally, only elderly subjects showed a pattern of liquid swallowing pressure generation in which multiple lingual gestures were required to reach peak pressure (termed "pressure building"), a pattern demonstrated by both young and elderly groups for semisolids.

CONCLUSIONS

Decreased lingual strength with age combined with unchanging swallowing pressure leads to a decreased "pressure reserve," perhaps leaving older individuals more at risk for dysphagia resulting from insults directly or indirectly to the swallowing system. Additionally, swallowing is generally "slowed" with age, apparently due to both central and peripheral factors, and this change may have an impact on bolus flow outcomes.

Oropharyngeal swallowing and aging: a review

This article provides an overview of normal oropharyngeal swallowing in relation to advanced age, with specific attention to oropharyngeal movement patterns and temporospatial swallowing durations. Swallowing disorders associated with aging are addressed with specific attention to the need for application of normative data to the diagnostic process. Attention is drawn to the need for continued research on swallowing function in the normal adult if efforts to maximize functional independence in eating and swallowing in the institutionalized adult are to be realized.

Neurophysiology of swallowing in the aged

The neurophysiology of normal swallowing and its alterations related to age are reviewed. Clinical implications in health and disease are discussed.

Neurogenic dysphagia: what is the cause when the cause is not obvious?

The potential causes of neurogenic oropharyngeal dysphagia in cases in which the underlying neurologic disorder is not readily apparent are discussed. The most common basis for unexplained neurogenic dysphagia may be cerebrovascular disease in the form of either confluent periventricular infarcts or small, discrete brainstem stroke, which may be invisible by magnetic resonance imaging. The diagnosis of occult stroke causing pharyngeal dysphagia should not be overlooked, because this diagnosis carries important treatment implications. Motor neuron disease producing bulbar palsy, pseudobulbar palsy, or a combination of the two can present as gradually progressive dysphagia and dysarthria with little if any limb involvement. Myopathies, especially polymyositis, and myasthenia gravis are potentially treatable disorders that must be considered. A variety of medications may cause or exacerbate neurogenic dysphagia. Psychiatric disorders can masquerade as swallowing apraxia. The basis for unexplained neurogenic dysphagia can best be elucidated by methodical evaluation including careful history, neurologic examination, videofluoroscopy of swallowing, blood studies (CBC, chemistry panel, creatine kinase, B12, thyroid screening, and anti-acetylcholine receptor antibodies), electromyography, and magnetic resonance imaging (MRI) of the brain, plus additional procedures such as lumbar puncture and muscle biopsy as indicated. Little is known about aging and neurogenic dysphagia, specifically the relative contributions of natural age-related changes in the oropharynx and of diseases of the elderly, including periventricular MRI abnormalities, in producing dysphagia symptoms and videofluoroscopic abnormalities in this population.

Pharyngeal constrictor paresis: an indicator of neurologic disease?

Pharyngeal constrictor paresis (PHCP) is sometimes found in videoradiography of the swallowing act in patients complaining of dysphagia. Ten patients with PHCP and 10 dysphagic, age- and sex-matched controls with normal videoradiography were neurologically evaluated and examined with magnetic resonance imaging (MRI) of the brain and brainstem in order to learn the pathogenetic process behind PHCP. The study revealed 8 PHCP patients and 1 dysphagic control with abnormal clinical neurological findings such as myopathy, cerebrovascular disease, or extrapyramidal disease. The neurological examination revealed considerable information of prognostic and therapeutic value in PHCP patients. The MRI was abnormal in 7 PHCP patients and 4 dysphagic controls. However, the findings in MRI were nonspecific but the examination was found to be valuable in selected cases. It is concluded that PHCP is an indicator of neurological disease and accordingly, such patients should be examined by a neurologist to establish the cause of the disease.

Clinically probable brainstem stroke presenting primarily as dysphagia and nonvisualized by MRI

Ten patients with clinically probable brainstem stroke presenting primarily as acute dysphagia but without visible brainstem abnormality by MRI are described. The patients were evaluated with neurologic examinations, cinepharyngoesophagography, and brain MRI studies. Each patient solely or predominately experienced sudden pharyngeal dysphagia, and additional symptoms or signs other than dysphonia or dysarthria were scarce. Small vessel disease or cardiac embolism were the apparent causes of what appear to have been very discrete brainstem strokes in these patients. Acute pharyngeal dysphagia can be the sole or primary manifestation of brainstem stroke. A negative MRI study should not preclude consideration of this diagnosis, if brainstem stroke is otherwise clinically probable.