Swallowing mechanism and neuromuscular disorders

Task-dependent neural control of regions within human genioglossus

Anatomical and imaging evidence suggests neural control of oblique and horizontal compartments of the genioglossus differs. However, neurophysiological evidence for differential control remains elusive. This study aimed to determine whether there are differences in neural drive to the oblique and horizontal regions of the genioglossus during swallowing and tongue protrusion. Adult participants (N=63; 48M) were recruited from a sleep clinic; 41 had Obstructive Sleep Apnoea (OSA: 34M, 8F). Electromyographic (EMG) was recorded at rest (awake, supine) using 4 intramuscular fine-wire electrodes inserted percutaneously into the anterior oblique, posterior oblique, anterior horizontal and posterior horizontal genioglossus. Epiglottic pressure and nasal airflow were also measured. During swallowing, two distinct EMG patterns were observed- a monophasic response (single EMG peak) and a biphasic response (two bursts of EMG). Peak EMG and timing of the peak relative to epiglottic pressure were significantly different between patterns (linear mixed models, p<0.001). Monophasic activation was more likely in the horizontal than oblique region during swallowing (OR=6.83, CI=3.46-13.53, p<0.001). In contrast, during tongue protrusion, activation patterns and EMG magnitude were not different between regions. There were no systematic differences in EMG patterns during swallowing or tongue protrusion between OSA and non-OSA groups. These findings provide evidence for functional differences in the motoneuronal output to the oblique and horizontal compartments, enabling differential task-specific drive. Given this, it is important to identify the compartment from which EMG is acquired. We propose that the EMG patterns during swallowing may be used to identify the compartment where a recording electrode is located.

Impaired opening of the upper esophageal sphincter in patients with medullary infarctions

The aim of this study was to report on nine dysphagic patients with medullary infarction and to evaluate swallowing characteristics based on the location of the lesions.We retrospectively reviewed the medical records of these nine patients. The medullary lesions were midlateral (three patients), dorsolateral (one patient), inferodorsolateral (four patients), and paramedian (one patient). The levels of the lesions were upper (four patients), middle (two patients), upper and middle (two patients), and middle and lower medulla (one patient). Dysphagia after medullary infarction was more common in patients with upper or middle medullary level and dorsolateral medullary level lesions. The common findings on videofluoroscopic swallowing studies in patients with lateral medullary infarctions were impaired upper esophageal sphincter opening, aspiration from pyriform sinuses' residue caused by pharyngeal weakness, and multiple swallowing to clear boluses from the pharynx to the esophagus. In patients with medullary infarctions, the lesion levels and loci and their related clinical findings can be useful in predicting dysphagia and aspiration. Because severe dysphagia with serious complication is very common in patients with medullary infarctions, active diagnostic and therapeutic approaches are needed.

Neurologisch bedingte und neuromuskuläre Funktionsstörungen des Pharynx und Ösophagus

Neurologic swallowing disorders are an increasing diagnostic problem in our overaged population. Undiagnosed chronic aspiration pneumonia is the cause of death in 20-40% of all inhabitants of nursing homes. In neurologic diseases of the pharynx, the physiologic interaction of pharyngeal contraction, closure of the pharynx, and esophageal motility are frequently disturbed. This may be due to cortical, bulbar, or cerebellar brain damage of ischemic or traumatic origin. Furthermore diseases or peripheral nerves, muscles, and synapses cause disturbances. The most life-threatening complication of these disturbances is tracheal aspiration, which requires an iso-osmolar contrast medium for imaging studies that cause no or minimal pulmonary problems. Utilizing fast dynamic documentation we can analyze the swallowing act in 35 images within the passage time of 0.7 s. This requires digital frame sequences from 15-50 images/s, which can be provided by DSI or videofluoroscopy. Neurologic and neuromuscular patterns are demonstrated with and without tracheal aspiration. The differentiation of aspiration in a so-called pre-, intra-, and postdeglutitive form is possible. We distinguish four grades of severity of aspiration, which is also of great clinical impact for the differential rehabilitation therapy. The efficiency of the rehabilitation protocol can be assessed by the dynamic swallowing studies.

Modified endoscopic swallowing test for improved diagnosis and prevention of aspiration

Laryngopharyngeal sensation is important in the normal process of swallowing, it is often impaired after neurological events and it has been common practice in such an occurrence to order non-oral tube feeding to prevent aspiration. This study assesses a novel approach to the evaluation of the laryngopharyngeal sensation that allows for improved triage of aspiration risk and more lenience towards oral feeding. This is a case series with follow-up period ranging from 6 to 24 months. Forty patients with neurological deficiencies were tested by a modified laryngopharyngeal sensation study that included evaluation of both supra and infra-glottis. All patients had impaired supra glottic sensation but had good infra glottic sensation that enabled cough protection. All had received oral feeding. Main outcome measure is incident aspiration pneumonia. Twenty-two patients maintained oral feeding without any evidence of aspiration. Eighteen patients had some aspirations associated with cough, and were maintained on modified oral feeding. Out of these 18 patients, four patients (10% of the entire group) developed aspiration pneumonia. The presented procedure identified patients with impaired supraglottic sensation but preserved good infra glottic sensation. This observation enables safe oral feeding in most patients and therefore offers a better quality of life for these individuals.

A case study of the resolution of paediatric dysphagia following brainstem injury: clinical and instrumental assessment

The coexistance of a swallowing impairment can severely impact upon the medical condition and recovery of a child with traumatic brain injury [ref.: Journal of Head Trauma Rehabilitation 9 (1) (1994) 43]. Limited data exist on the progression or outcome of dysphagia in the paediatric population with brainstem injury. The present prospective study documents the resolution of dysphagia in a 14-year-old female post-brainstem injury using clinical, radiological and endoscopic evaluations of swallowing. The subject presented with a pattern of severe oral-motor and oropharyngeal swallowing impairment post-injury that resolved rapidly for the initial 12 weeks, slowed to gradual progress for weeks 12-20, and then plateaued at 20 weeks post-injury. Whilst a clinically functional swallow was present at 10 months post-injury, radiological examination revealed a number of residual physiological impairments, reduced swallowing efficiency, and reduced independence for feeding, indicating a potential increased risk for aspiration. The data highlight the need for early and continued evaluation and intensive treatment programs, to focus on the underlying physiological swallowing impairment post-brainstem injury, and to help offset any potential deleterious effects of aspiration that may affect patient recovery, such as pneumonia.

Dysphagia in patients with brainstem stroke: incidence and outcome

OBJECTIVE

This study was conducted to delineate the incidence and outcome of dysphagia among hospitalized patients who were referred for rehabilitation because of brainstem stroke.

DESIGN

We retrospectively reviewed the medical records of 36 patients who were admitted because of brainstem stroke. Information on the patients' clinical features, feeding status, and the results of clinical and videofluoroscopic swallowing examinations were obtained through chart review. Follow-up interviews were conducted via telephone to learn the general medical condition and feeding status of the patients 7-43 mo after hospital discharge.

RESULTS

A total of 81% of the patients had dysphagia at the time of initial clinical swallowing evaluation, which was performed 10-75 days after the onset of stroke. A total of 79% of the dysphagic individuals depended on tube feeding at the initial evaluation; 22% of all individuals could not resume oral intake at discharge. Statistical analyses revealed a significant association between poor outcome and disease involving the medulla, the presence of a wet voice during the initial swallowing test, and a delay or absence of the swallowing reflex. The incidence of aspiration pneumonia was 11%. There was a correlation between the detection of aspiration by modified barium meal videofluoroscopy and the development of aspiration pneumonia. Follow-up interviews showed that 88% of the 27 patients who were contacted had resumed full oral intake 4 mo after the onset of stroke.

CONCLUSIONS

The incidence of dysphagia was relatively high in our study population. The long-term outcome was favorable.

Percutaneous endoscopic gastrostomy in neurological rehabilitation: a report of six cases

PURPOSE

This study reports the cases of six patients with severe chronic neurological disability and swallowing difficulties due to traumatic brain injury (TBI), anoxia and multiple sclerosis (MS).

METHOD

The patients required nutritional supplement through percutaneous endoscopic gastrostomy (PEG).

RESULTS

Their clinical follow-up showed a decrease of intercurrent medical complications, especially pressure sores. In addition, an improvement of oropharyngeal function was observed in some patients, also accompanied by slightly better basic psychomotor functions such as vigilance, sustained attention and tone or motor control. However, not every patient did improve with this procedure. The two MS patients benefited most, while the improvement was less homogenous in the three TBI patients.

CONCLUSIONS

The advantages of PEG over nasogastric tube on oropharyngeal function can be related to the absence of pharyngeal irritation and its role in overall recovery could be due to an increase in social activities, a control of infections, a better rehabilitation schedule and a long-term effect on brain function due to better nutritional support.

Nutrition and swallowing in pediatric neuromuscular patients

The management of the patient with neuromuscular disease is complex. Every child should be seen as a distinct individual and therefore merits patient-specific assessment and intervention. This article reviews nutritional management using spinal muscular atrophy and Duchenne's muscular dystrophy as representative models. The history of nutritional intake, nutritional needs, and underlying medical problems with physical examination, anthropometric, body composition, and biochemical markers are all important parts of the assessment and should be done at regular intervals. Intervention may include calorie restriction or calorie supplementation. Treatment strategies that follow diagnosis of dysphagia include positioning, increased sensory input, or direct maneuvers, such as volume changes or thickening liquid. Percutaneous endoscopic gastrostomy can be safely placed in almost all situations with minimal risk. Patients benefit most from a multidisciplinary and systematic management program.

Dysphagia caused by neurologic deficits

This article provides a brief review of the neurophysiology behind the normal swallow. The examination and work-up of a patient with dysphagia is then detailed. Finally, the major neurologic conditions associated with dysphagia are considered.

Laryngopharyngeal sensory testing with modified barium swallow as predictors of aspiration pneumonia after stroke

Improved diagnostic tests that can accurately identify subjects at high risk for aspiration pneumonia (AP) are needed. One measure of this accuracy is the false-negative rate (FNR), which determines the failure of a test to identify a group at high risk. This study compares FNRs for AP among dysphagic stroke patients for two prognostic techniques: modified barium swallow (MBS) alone and MBS combined with laryngopharyngeal sensory discrimination testing (MBS + LPSDT). MBS and LPSDT were performed within 4 weeks of stroke in 20 subjects who were prospectively followed for at least 2 years to identify the frequency of AP. MBS identified 10 patients as not at risk based on the finding of no aspiration on initial MBS; four of these patients developed AP (FNR = 40%). MBS + LPSDT identified five patients as not at risk based on the findings of neither aspiration nor bilateral sensory deficits; none of these patients developed AP (FNR = 0%). The combination of MBS criterion (aspiration) with the LPSDT criterion (bilateral sensory deficits) improves prognostication of outcome in dysphagic stroke patients by identifying a subgroup at high risk for developing AP (nonaspirators with bilateral deficits).

Supraglottic and pharyngeal sensory abnormalities in stroke patients with dysphagia

Dysphagia and aspiration are two devastating sequelae of stroke, accounting for nearly 40,000 deaths from aspiration pneumonia each year in the United States. While motor deficits in the larynx and pharynx are thought responsible for dysphagia and aspiration in stroke patients, no prior study has evaluated whether these patients also have sensory deficits. The aim of this study was to evaluate the sensory capacity of the laryngopharynx (LP) in supratentorial or brain stem stroke patients who presented with dysphagia. Fifteen stroke patients (mean age, 66.7 +/- 13.8 [SD] years) were prospectively evaluated by means of our previously described method whereby air pulse stimuli were delivered via a flexible fiberoptic telescope to the mucosa innervated by the superior laryngeal nerve. There were 15 age-matched controls. No LP sensory deficits were found in any of the age-matched controls. In all stroke patients studied, either unilateral (n = 9) or bilateral (n = 6) sensory deficits were identified. Deficits were defined as either a moderate impairment in sensory discrimination thresholds (3.5 to 6.0 mm Hg) or a severe sensory impairment (> 6.0 mm Hg). These sensory discrimination thresholds were significantly greater than in age-matched controls (7.05 +/- 0.17 mm Hg for the supratentorial group and 6.05 +/- 1.22 mm Hg for the infratentorial group versus 2.61 +/- 0.69 mm Hg for the controls). Among patients with unilateral deficits, sensory thresholds were moderately to severely elevated in all 9 cases on the affected side compared with the unaffected side (p < .01, Fisher's exact test). Moreover, the sensory thresholds of the unaffected side were not significantly different from those of age-matched controls (2.51 +/- 0.25 mm Hg versus 2.61 +/- 0.69 mm Hg, respectively). All 6 patients with bilateral deficits had severe impairments. The results of an outcome assessment in 13 of 15 patients revealed that 2 out of 5 patients with moderate LP sensory impairment and 5 out of 8 with severe impairment developed aspiration. Our results show for the first time that stroke patients with dysphagia have significant sensory deficits in the LP and that these impairments are likely to contribute to the development of aspiration.

Malnutrition in stroke patients on the rehabilitation service and at follow-up: prevalence and predictors

This prospective study presents the prevalence and risk factors of malnutrition in 49 consecutive stroke patients on the rehabilitation (Rehab) service and at 2- to 4-month follow-up. Malnutrition was diagnosed using biochemical and anthropometric data. Stroke patients, on admission to Rehab, have a very high prevalence of malnutrition. Malnutrition, 49% on admission, declined to 34%, 22%, and 19% at 1 month, 2 months, and follow-up, respectively. Dysphagia, 47% on admission, was associated with malnutrition (p = .032) and significantly declined over time. Using logistic regression, predictors of malnutrition on admission involved acute service tube feedings (p = .002) and histories of diabetes (p = .027) and prior stroke (p = .013). Tube feedings, associated with malnutrition on admission (p = .043), were more prevalent in brain stem lesion patients. Patients tube fed > or = 1 month during rehabilitation or at home were not malnourished. Malnutrition was associated with advanced (> 70 years) age at 1 month (p = .002) and weight loss (p = .011) and lack of community care (p = .006) at follow-up. Early and ongoing detection and treatment of malnutrition are recommended during rehabilitation of stroke patients both on the service and at follow-up.

A direct intervention program for chronic neurogenic dysphagia secondary to brainstem stroke

Little objective documentation is available regarding the efficacy of therapies for oropharyngeal dysphagia. Information specifying efficacy of treatment for chronic dysphagic conditions is almost nonexistent. This report describes a direct therapy program for chronic neurogenic dysphagia resulting from brainstem stroke, and provides information on immediate and long-term clinical outcome. Changes in swallowing physiology reflect goals of therapy. Long-term follow-up shows that functional benefits are long lasting without related health complications.

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.

Effect of aging on the deglutitive oral, pharyngeal, and esophageal motor function

Aging affects some members of the swallowing orchestra and spares the others. It seems that changes in the pharynx of the elderly are more of a positive nature than a negative one and reflect an adaptation to age-induced structural changes of the upper esophageal sphincter. In the esophagus, the positive change in deglutitive peristaltic amplitude and duration seem to revert to a negative one over the age of 90 years. In the upper esophageal sphincter, it appears that aging reduces the resting pressure, but spares its response to various stimuli. Considering the increasing elderly population and their medical needs, further normalcy data about various manometric aspects of deglutition is needed for physiologic studies as well as diagnostic and therapeutic purposes.

Dysphagia diagnostics and Donner: experiences in the decade of change

Martin Donner's influence in the area of dysphagia diagnostics has spanned several decades and has provided an impetus for the evolution of advanced dysphagia diagnostics. This article presents an historical perspective of the development of ultrasound imaging and the variety of other imaging procedures to evaluate swallowing. The future of image processing for dysphagia is firmly set.

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.

Oropharyngeal swallowing after stroke in the left basal ganglion/internal capsule

One of the foci of Martin Donner's work was the neural control of swallowing. This present investigation continues that work by examining oropharyngeal swallowing in 8 patients identified with a single, small, left-basal ganglion/internal capsule infarction and 8 age-matched normal subjects. Stroke patients were assessed with a bedside clinical and radiographic swallowing assessment, and normal subjects received only the radiographic study. Results revealed disagreement between the bedside and radiographic assessments in one of the 8 stroke patients. Stroke and normal subjects differed significantly on some swallow measures on various bolus viscosities, but behaved the same as normal subjects on a number of measures. Differences in swallowing in the stroke subjects were not enough to prevent them from eating orally. The significant differences seen in the basal ganglia/internal capsule stroke subjects may result from damage to the sensorimotor pathways between the cortex and brainstem. These differences emphasize the importance of cortical input to the brainstem swallowing center in maintaining the systematic modulations characteristic of normal swallowing physiology.

Scintigraphy for the detection and quantification of subglottic aspiration: preliminary observations

Eleven patients with previously documented aspiration underwent a radioisotopic swallowing study to detect and quantify airway penetration. In those subjects able to complete a rapid-acquisition phase during swallowing, no laryngotracheal penetration was seen despite previous evidence of aspiration. However, sequential static pulmonary imaging showed significant aspiration in three individuals. Attempts were made to measure the percentage of ingested material aspirated and the clearance rate from the airways. Eight patients (73%) failed to show definite evidence of aspiration on scintigrams. It is hypothesized that the lack of scintigraphic detection in previously proven aspirators was due either to interval improvement of the dysphagia or to difficult-to-detect laryngotracheal aspiration. Isotopic imaging during swallowing appears to have little utility; however, after ingestion, the technique can demonstrate more distal penetration not detected on videofluoroscopy. More studies are suggested to better define the sensitivity and specificity of scintigraphy in aspiration detection and to determine whether these techniques have prognostic value that could alter patient management.

Development of a multidisciplinary feeding profile for children who are dependent feeders

The multidisciplinary feeding profile (MFP) is the first statistically based protocol for the quantitative assessment of feeding disorders in severely disabled children. This assessment can be completed in 30-45 min with foods and facilities that are available in homes, hospitals, and chronic care units. This paper describes the state of current testing methods, the parameters of successful feeding activity, the development of the test protocol, and the results of statistical analyses.

Esophageal motility disorders

Esophageal motility disorders consist of a complex array of disturbances in normal esophageal function associated with dysphagia, gastroesophageal reflux, and noncardiac chest pain. A thorough knowledge of normal esophageal anatomy and physiology is important to a full understanding of these motility derangements. Through a complicated interaction of neuromuscular and hormonal influences, the voluntary act of swallowing transforms into an automated sequence of peristaltic waves propelling food and liquids into the stomach in concert with coordinated relaxation of the sphincters. Anatomic and physiologic barriers exist within the esophagus protecting against gastroesophageal reflux and aspiration. With improvements in diagnostic tools such as barium contrast radiography, scintigraphy, pH measurements, and esophageal manometrics with provocative testing, motility disorders have become better defined and understood. Primary motility disorders consist of achalasia, diffuse esophageal spasm (DES), "nutcracker esophagus," hypertensive lower esophageal sphincter, and nonspecific esophageal motility dysfunction (NEMD). A host of secondary and miscellaneous motility disorders also affect the esophagus, including scleroderma and other connective tissue diseases, diabetes mellitus, Chagas' disease, chronic idiopathic intestinal pseudo-obstruction, and neuromuscular disorders of striated muscle. Gastroesophageal reflux disease (GERD) may also be promoted by associated motility disturbances. Treatment modalities include surgical myotomy; dilatation; and pharmacologic manipulations, including use of nitrates, calcium-channel blockers, H2-blockers, and psychotropic drugs where appropriate.

Dysphagia in the adult population:

Occupational therapists, traditionally concerned with activities of daily living, are now addressing the problems of eating caused by dysphagia. Adult-onset dysphagia results from either neurological or mechanical, i.e., structural, causes. Following a description of the normal swallowing process, this paper reviews the various disorders that cause dysphagia. General evaluation principles are offered with treatment methods appropriate to the category of disorders. Although specific treatment methods have been used clinically, many remain untested. More recently, a growing number of studies have been published which measure the effectiveness of rehabilitation for dysphagics. Active intervention in the problem of adult-onset dysphagia consists largely of detailed evaluation of oral structures, manipulation of diet, techniques to elicit normal swallowing mechanisms, and assistive devices to compensate for lost structures. In addition, cognitive status, nutrition, posture, and position are addressed in a comprehensive therapy program. The goal of treatment is to promote a safe and nutritional oral diet to the fullest extent possible.

Derangement of swallowing in children with myelomeningocele

Barium esophagrams performed in 13 children with myelomeningocele demonstrated a variety of swallowing disorders: difficulty in bolus formation, nasopharyngeal reflux, tracheobronchial aspiration. Cricopharyngeal spasm was not identified in this group. Antegrade peristalsis in the distal two-thirds of the esophagus was normal. Gastroesophageal reflux was demonstrated in 8 of the children. Vocal cord paralysis (8/13) and death in early children (7/13) occurred with greater frequency than in the general myelomeningocele population. Correct management of these children may require tracheostomy, gastrostomy, and fundoplication.

The pharyngo-laryngeal deficit in the acute form of infantile spinal muscular atrophy (Werdnig-Hoffmann disease)

The major complication in the acute form of infantile spinal muscular atrophy is the aspiration phenomenon, due to the pharyngo-laryngeal deficit. The radiographic findings of this deficit are characterized by epipharyngeal regurgitation, hypopharyngeal distention, good function of the cricopharyngeal sphincter and absence of epiglottic closure during the act of deglutition. The differential diagnosis of other neuromuscular entities is discussed in view of two documented radiographic cases.