16 Swallowing Disorders in the Elderly
Introduction
According to the U.S. Department of Health and Human Services, persons over the age of 65 currently represent 12.9% of the American population. As the fastest-growing segment of the population, this age group is expected to expand to 30% by the year 2030. Dysphagia is a growing health concern in the aging population. Its prevalence is high in both the unhealthy and the community-dwelling elderly population and is associated with increased risks of malnutrition and aspiration pneumonia.1 Although the exact incidence of dysphagia across different settings is unclear, conservative estimates suggest that 15% of the geriatric population is affected by dysphagia.1 The prevalence is much higher in selected populations, such as patients residing in nursing homes, who have reported rates as high as 30 to 40%.2 Aside from leading to malnutrition, dehydration, and aspiration pneumonia, dysphagia also has major effects on social and psychological well-being.3 Due to the complex nature of the swallowing system and because the workup and treatment encompasses multiple disciplines, several aspects of the problem remain poorly understood.
Changes in the Physiology of Swallowing with Aging
Age-related changes place older adults at risk for dysphagia for two major reasons: first, natural, healthy aging alters head and neck anatomy as well as the physiological and neural mechanisms that sustain swallowing function. This progressive change contributes to the alterations in swallowing in healthy older adults, and is termed presbyphagia, which is also associated with a diminished functional reserve. Second, disease prevalence increases with age, and dysphagia is a comorbidity of many age-related diseases and/or their treatments.4
Swallowing incorporates a complex system of both voluntary and involuntary sensory and motor behaviors. Six cranial nerves and ~ 40 sets of bilaterally innervated muscles coordinate the upper aerodigestive system, which coordinates the main functions of breathing and swallowing. Swallowing occurs in four phases: the oral preparatory, oral phase, pharyngeal phase, and esophageal phase. A large number of muscles and structural movements of bone and cartilage are involved in the following tasks: (1) preparing food in the mouth for swallowing, (2) propelling food through the oral cavity, and (3) propelling food through the pharynx and into the esophagus.5 To execute swallowing safely, the upper aerodigestive tract reconfigures from a system that valves and moves air for the purposes of breathing and talking to one that interrupts airflow and protects the airway while food, fluid, secretions, and medications are allowed to move into the digestive system for nutrition and hydration.4 With aging, a reduction in muscle mass and connective tissue elasticity results in loss of strength and range of motion.1 Aging causes several significant changes in the oropharyngeal swallow, although usually the swallowing mechanism maintains a functional ability to propel food safely and efficiently from the mouth through the pharynx and into the esophagus. The overall effect of aging is to slow deglutition and to mildly but significantly reduce swallowing efficiency.6
The oral tongue is the primary propulsive force controlling and forcing the bolus into the pharynx. Todd et al corroborated the findings of Robbins et al and others who reported that isometric tongue strength decreases with age. Furthermore, they demonstrated that, since young and older adults generate similar swallowing tongue strength, swallowing is a submaximal strength activity; yet older adults have less functional reserve.7–9 The decrease in isometric tongue strength in older adults has been postulated to be due to generalized weakening of skeletal muscle caused by sarcopenia.10 Nicosia et al showed that patients with oral phase dysphagia had lower isometric tongue strength compared with a control group; and Lazarus et al confirmed similar findings in patients with head and neck cancer.10,11 The role of tongue strengthening exercises in the treatment of dysphagia is not yet clear and requires further evaluation.
Another significant change in pharyngeal swallow with aging is a slightly delayed triggering of the pharyngeal stage.5 In those over age 65, the initiation of laryngeal and pharyngeal events, including laryngeal vestibule closure, is significantly longer than in younger adults.6 Although this may put the elderly at risk for penetration and aspiration, in this population the importance of either one of these consequences is still not thoroughly understood. Using flexible endoscopy and the penetration aspiration scale (PAS), Butler and colleagues reported the prevalence of penetration and aspiration to be 15 and 6.5%, respectively, in normal elderly individuals.12 Alternatively, Allen et al suggested that penetration and aspiration during swallowing represent pathological entities that are not present in people with normal swallowing function. They looked at the prevalence of penetration and aspiration on videofluoroscopic swallowing studies (VFSSs) in normal individuals without dysphagia. One individual aspirated on VFSS, and penetration, which was present in 11.4% of normal adults, was even more common with a liquid bolus.13 Although the implications of penetration and aspiration continue to be studied, one of the well-known associated risk factors is pooling in the pyriform sinuses and the resultant overflow into the laryngeal vestibule. Upper esophageal sphincter (UES) dysfunction can be a major contributor to postswallow residues. Logemann et al evaluated the biomechanics of the swallowing of eight healthy adults between 21 and 29 years old and eight healthy adults over 80 years old. The study revealed that the movement of the hyoid and larynx to open the UES was identical to the point of the upper sphincter opening for both groups. However, there was a significant difference between the hyoid and laryngeal movements after UES opening. Following the UES opening, the younger men continued the anterior motion of the hyoid bone until they achieved upper sphincter opening and went further by 8 mm. In older subjects, the hyoid anterior movement was just enough to get the UES open and only 1 to 2 mm more. The difference between the amount of hyoid anterior movement needed to open the upper sphincter and the anterior amount of movement actually used in total reflects the functional reserve present in any given individual. Logemann and colleagues concluded that, although older men seemed to be more efficient in hyoid anterior movement and achieving UES opening, they in fact exhibited no reserve. Functional reserve is needed to assist in recovery when someone becomes ill and loses muscle strength.14
Contributing Factors
Skeletal muscle strength begins to decline at approximately age 45 and is associated with a 30 to 40% decrease in strength by the age of 80.15 This loss of muscle mass not only causes a reduction in strength, but also may be responsible for as much as a 30% decline in the highest rate of oxygen utilization an individual can achieve while performing an exercise requiring substantial skeletal muscle mass.16 Loss of skeletal muscle mass below a critical threshold, known as sarcopenia, leads to functional impairment and frailty. Sarcopenia of the lingual muscles correlates with malnutrition, and tongue thickness also correlates with midarm muscle area thickness. It has been suggested that exercises improving tongue thickness and strength could improve oropharyngeal dysphagia.17
Xerostomia can hinder bolus flow and results in the retention of material along the upper digestive tract. Functional salivary production has been shown to remain fairly stable throughout the age spectrum, although older adults have some decrease in salivary reserve due to the loss of saliva-producing acinar cells. Consequently, the drying effects of medications are generally more pronounced in older adults.4 More than 400 drugs are known to cause xerostomia, and the older adult is generally on multiple classes of drugs known to be offenders, such as anticholinergics, antihypertensives, antipsychotics, anti-Parkinson agents, diuretics, and sedatives. Xerostomia can also result from diseases such as Sjögren syndrome and scleroderma.
Neurological and neuromuscular disorders are among the most important causes of dysphagia in older adults. Stroke, Alzheimer disease, dementia, and Parkinson disease are all commonly associated with dysphagia. Dysphagia is highly prevalent following stroke, with estimates ranging from 30 to 65%.18,19 Complications associated with poststroke dysphagia include pneumonia, malnutrition, dehydration, increased length of hospital stay, increased rehabilitation time, increased mortality, and increased health care costs.1,4,20 About 25% of stroke patients die of aspiration pneumonia within the first year of rehabilitation.
It has been estimated that up to 45% of patients institutionalized with dementia have some degree of swallowing difficulty.21 Patients with dementia show slowing of the swallowing process, which may lead to increased time needed to finish meals and, as a result, malnutrition. In addition, cognitive impairment, motor deficits, and loss of appetite lead to further difficulties with feeding. Pneumonia is one of the many dysphagia-related health problems seen in this group, and indeed is one of the common causes of mortality.1,22
Clinical Assessment: History
Dysphagia is likely to be underestimated in the older adult. Often perceived as a normal part of aging, it may not be brought up by the patient as a complaint until significant changes in diet have been made to compensate. Therefore, diligence is necessary and mandates a thorough history on all geriatric patients. Most patients will present with the complaint of “food getting stuck” in their throat. The site at which a patient localizes dysphagia is of limited value. Although dysphagia in the retrosternal or epigastric areas frequently corresponds to the site of obstruction, dysphagia localized to the neck may be from either the lower esophagus or the hypopharynx.23 Nonetheless, a careful history can help differentiate between oropharyngeal and esophageal dysphagia. Patients with oropharyngeal dysphagia will more commonly exhibit symptoms of coughing/choking during meals, especially with liquids. They may also have nasal regurgitation and problems with oral competence.
A clear understanding of the current diet of the patient is important. The types of foods causing difficulty should be determined, as well as the number of meals eaten during a day, aiming to understand whether the patient has an adequate nutritional intake. Unintentional weight loss in the elderly is generally a sign of malnutrition and increases the risk of opportunistic infections such as pneumonia. By leading to malnutrition, dysphagia promotes frailty, which in turn may worsen the dysphagia in older adults.
Aspiration risk should be carefully assessed and may be present at either initial swallow or postswallow due to residue in the hypopharynx. As a result of altered superior laryngeal nerve function in this population, silent aspiration is not rare. A history of aspiration pneumonia and hospitalizations should be sought and noted. In the United States, the prevalence of aspiration pneumonia in nursing homes has been reported to be as high as 8%.24
Regurgitation of undigested food, solid food dysphagia, borborygmi in the throat, postprandial or nocturnal coughing, and halitosis are all symptoms that should raise suspicion of the presence of a Zenker diverticulum. These patients are also at risk for malnutrition, dehydration, and aspiration pneumonia. A history of neurological disorders, prior surgeries, or head and neck cancer treatment should alert the clinician to the possibility of dysphagia. The cognitive status of the patient is of importance to understand the inherent difficulties with feeding as well as to plan therapeutic strategies.
Physical Examination
A thorough head and neck examination with special attention to cranial nerve function should be performed. In examining the oral cavity, the presence of xerostomia should be noted. Indirect or direct (flexible) laryngoscopy, an integral part of the examination, may reveal pooling in the vallecula or pyriform sinuses, vocal fold hypo-/immobility, or a glottic gap during phonation (incomplete glottic closure).
The pharyngeal squeeze maneuver (PSM) first described by Bastian is a simple yet very valuable test to evaluate pharyngeal function during flexible laryngoscopy.25 The patient is asked to make a high-pitched, strained phonation, preferably with increasing effort. This will, in a normal pharynx, result in obvious recruitment of the pharyngeal constrictor musculature.25,26 This recruitment is reduced or absent in patients with dysphagia. Belafsky and colleagues reported a good correlation between the PSM and the pharyngeal constriction ratio, which is a validated measure of pharyngeal strength.27
Diagnostic Evaluation
The clinical examination should aim to accomplish several purposes: (1) to identify possible causes of dysphagia and assess swallowing safety or risk of aspiration, (2) to decide on oral versus alternative feeding routes, (3) to clarify the need for further assessment, and (4) to establish baseline or pretreatment clinical data to be compared with follow-up assessment after intervention or during the course of progressive diseases.28
Bedside evaluation techniques have been shown to be of limited value in assessing dysphagia.29 Numerous methods can be used for bedside evaluation, more commonly in hospitalized patients, aiming to identify those at risk for aspiration. The main advantage of bedside evaluation is that many of the health care providers, such as the nursing staff who generally have initial contact with the patient, can be trained in bedside evaluations, triggering a formal assessment if needed.
Patient self-evaluation can be helpful in determining functional health status and health-related quality of life. Developed by Belafsky et al, the Eating Assessment Tool (EAT-10) is a useful clinical instrument for documenting initial dysphagia severity and the patient’s treatment response.30 The MD Anderson Dysphagia Inventory, developed for head and neck cancer patients, and the Sydney Swallow Questionnaire are some of the other instruments available for patient self-assessment.31,32
Methods of Evaluation
Flexible Endoscopic Evaluation of Swallowing and Sensory Testing (FEES and FEESST)
These are convenient and efficient methods of testing that can be performed in the clinic and the in-patient setting. They were introduced by Langmore and colleagues in the late 1980s.33,34 The principle advantages of flexible endoscopic evaluation of swallowing (FEES) include (1) direct observation of the laryngopharyngeal anatomy, (2) ease of execution in every otolaryngology office, (3) no need for a radiology technician, and (4) no X-ray exposure or administration of barium. Limitations of FEES include (1) it does not allow evaluation of the oral phase, and (2) evaluation of the pharyngeal phase is limited owing to the “whiteout” that occurs during swallowing. However, premature spillage, penetration and aspiration, pooling in the vallecula and pyriform sinuses, and spillage into the larynx due to postswallow residue can all be thoroughly evaluated. Although FEES is limited in showing UES transit, residue in the pyriform sinuses may be an indirect sign of UES dysfunction.
The importance of sensation in swallowing and hence airway protection has been studied extensively. In flexible endoscopic evaluation of swallowing and sensory testing (FEESST), airway protection is assessed by the delivery of a discrete pulse of air to the epithelium innervated by the internal branch of the superior laryngeal nerve to elicit the laryngeal adductor reflex, a brainstem-mediated airway-protective reflex.35 This enables the clinician to obtain vital information about potential performance before the administration of any food bolus.36 Setzen et al reported a strong association between motor function deficits and hypopharyngeal sensory deficits. In their study, patients with an absent laryngeal adductor reflex showed significant aspiration with thin liquids and pureed foods.36
Videofluoroscopic Swallowing Study (VFSS)
Also known as a modified barium swallow (MBS) study, VFSS is the mainstay of dysphagia evaluation. This is the only study that will show all four phases of swallowing. VFSS is useful in (1) identifying existing oral and pharyngeal motility disorders, (2) ascertaining the presence of penetration or aspiration during swallowing of any food consistency, (3) assessing the speed of the swallow, and (4) evaluating the effects of therapeutic strategies such as postural changes, and swallowing maneuvers.37 VFSS is also useful in monitoring response to therapy. If esophageal pathology is suspected, VFSS can be ordered to be followed by a formal esophagogram during the same visit. An important advantage to this approach is that aspiration is ruled out during the VFSS. Therefore, the patient can safely be given higher volumes of barium. Not doing a formal esophagogram, but rather using a single esophageal screening swallow, has been reported to have a limited sensitivity (63%).38
Transnasal Esophagoscopy (TNE)
With transnasal esophagoscopy (TNE), the entire upper aerodigestive tract from the nasal vestibule to the gastric cardia can be visualized safely.39 It is easy to perform, well tolerated, safe, and requires only topical anesthesia. Indications include dysphagia, globus sensation, laryngopharyngeal and gastroesophageal reflux, and head and neck cancer screening. The relatively high prevalence of esophageal pathology in this group makes TNE an important addition to the diagnostic armamentarium.39
Pharyngeal and Esophageal Manometry
Pharyngeal and upper esophageal sphincter manometry allows for objective measurement of pharyngeal and UES coordination and quantitative pressures. Pharyngeal strength and contraction duration, the completeness of UES relaxation, and coordination between the pharynx and UES during swallowing can also be evaluated.40
Esophageal manometry is used to examine upper and lower sphincter function, as well as esophageal peristalsis. Decline of peristaltic amplitude and ineffective peristalsis, polyphasic waves in the esophageal body, incomplete sphincter relaxation, and esophageal dilation have been reported in healthy older adults.41–43
Adjunct Testing
Depending on the patient’s symptoms 24 hour pH-impedance testing, scintigraphy, ultrasonography, and computed tomography may also be useful in diagnostic testing.
Management
The two principal goals in managing geriatric dysphagia include (1) ensuring that swallowing is safe and the airway is protected and (2) preventing dehydration and malnutrition. Although at times these goals can be achieved through surgical means, the mainstays of treatment consist of swallowing therapy, dietary modifications, and close monitoring of nutritional intake. A multidisciplinary team approach to dysphagia, which includes nurses, dietitians, speech-language pathologists, occupational and physical therapists, as well as primary care physicians, neurologists, otolaryngologists, and gastroenterologists ensures comprehensive and successful management.
Surgical Management
Zenker diverticulum, cricopharyngeal (CP) achalasia and aspiration, all of which are more prevalent in the geriatric population, can be managed successfully with surgery.
With the advancement of endosurgical techniques, endoscopic approaches to Zenker diverticulum and CP achalasia have gained popularity. The apparent advantages of shorter surgical times, shorter or no hospital stay, earlier return to a normal diet, and increased patient comfort have been reinforced by reduced complication rates.44–46 These are all significant benefits in a patient population usually presenting with a myriad of comorbidities and frailty due to malnutrition. Traditional open approaches, despite the advantage of providing tissue for histopathological analysis in the case of a Zenker diverticulum, are generally associated with longer hospital stays and higher rates of complications that include fistula formation and vocal fold paralysis.47 In managing a Zenker diverticulum (Figs. 16.1 and 16.2), the decision regarding surgery and what approach to employ depends on how symptomatic the patient is, the risk of aspiration pneumonia, surgical risk stratification, the size of the diverticulum, and the anatomy of the patient.
The most important component of successful surgical management is correct patient selection. Unfortunately, there are no well-established guidelines for either a Zenker diverticulum or CP achalasia, and practices vary from institution to institution. There is no gold standard diagnostic test for dysfunction of the CP. Most commonly, diagnosis is based on findings of postcricoid pooling on flexible laryngoscopic examination and abnormalities on videofluoroscopy. The latter, however, is largely subjective, and postcricoid pooling is nonspecific. As a result, clinical suspicion plays an important role in decision making.48 Improvement in symptoms following botulinum toxin injections into the CP muscle has been used as a diagnostic tool, and further treatment has sometimes been based on the outcomes of therapeutic trial injections. Interestingly, Lawson and Zaninotto et al reported a 72.7% success rate with CP myotomy in patients who did not respond to botulinum toxin injection.49,50
