Flexible Endoscopic Evaluation of Swallowing with Sensory Testing (FEESST)

Flexible endoscopic evaluation of swallowing with sensory testing (FEESST) is a technique used to evaluate the patient with dysphagia, or difficulty swallowing. Dysphagia is one of the most common problems affecting the population as it ages and is one of the most likely reasons why patients consult with an otolaryngologist as they get older. Swallowing should be thought of as an interaction between two related physiologic entities: airway protection and bolus transport.1 Airway protection is determined by assessment of the sensory component of swallowing, and bolus transport is determined by assessment of the motor component of swallowing. This chapter discusses the magnitude of swallowing problems in the population in general, the likely reasons why individuals have swallowing difficulties, and the diagnostic techniques necessary to fully evaluate the patient with dysphagia. Emphasis is placed on the FEESST technique to assess the severity of dysphagia.

Epidemiology of Dysphagia

The ubiquitous nature of swallowing problems is demonstrated by examining the incidence of swallowing problems after stroke. Stroke affects 400,000 people a year and results in an incidence of dysphagia ranging from 35 to 47%.2,3 Patients succumb after a stroke primarily because of pulmonary complications, specifically aspiration pneumonia. Approximately 50,000 people die each year as a result of aspiration pneumonia after stroke.^4,5 Although the development of aspiration pneumonia is a multifactorial process, several studies have demonstrated a significant association between dysphagia and aspiration pneumonia. Dysphagia often results in difficulty handling food and secretions, a consequence of which is foreign material soiling the lungs.^6–10

Aspiration pneumonia is also a significant cause of chronic illness in the elderly residing in United States nursing homes and is the most common reason why residents of nursing homes are transferred to a hospital.^11,12 In U.S. nursing homes the prevalence of aspiration pneumonia has been reported to be as high as 8%.^13–16 The cost of treating a single episode of pneumonia in a hospital, including intravenous antibiotics and a stay in an intensive care unit, with or without respiratory support, averaged $30,400 in 2008.¹⁷ This treatment cost has escalated in proportion to other medical costs since that time. Extrapolating to the current population of 2 million people in nursing homes, the annual health care costs related to aspiration pneumonia from the nursing home population is over $3 billion per year. Although the mortality from aspiration pneumonia can approach 40%, it is not the first episode of pneumonia that results in demise; rather, it is recurrent pneumonia over a several-year period that is so deadly and so costly.^4,5

Etiology of Dysphagia

As one ages, dysphagia and aspiration during swallowing are more likely to occur.18,19 The primary explanations for these observations have been oral and pharyngeal motor dysfunctions such as abnormal lingual activity, poor lingual–palatal seal, and pharyngeal pooling.^18,20 Although oropharyngeal motor dysfunction contributes to swallowing difficulties, it has also been shown that oral cavity sensory discriminatory ability diminishes with advancing age.^21,22 Over the past decade laryngopharyngeal sensory capacity has been studied in the elderly, and it has been demonstrated that airway protective capacity also diminishes as people age. Specifically, with aging there is a progressive increase in the stimuli required to elicit fundamental airway protective reflexes, with patients 61 years and older requiring a more intense stimuli than those 60 and younger.²³ In a study of fresh human cadavers, changes in sensory nerve composition that take place with increasing age in the human superior laryngeal nerve (SLN) were examined.²⁴ It was found that there is an extensive and statistically significant decrease in the number of sensory nerve fibers in subjects over 60 years of age.²⁴ Because it is the SLN that provides afferent fibers to the hypopharynx from the laryngeal surface of the epiglottis to the level of the true vocal folds, this basic science work supports the aforementioned clinical studies.

Although the healthy elderly develop a progressive diminution in both airway protective capacity and motor capabilities as they age, the unhealthy elderly, such as those who suffer from stroke, progressive neuromuscular diseases, diabetes, and a general decline in health status, suffer even more of an assault to their airway protective capacity and muscular coordination.25–27 Studies evaluating sensory capacity of the laryngopharynx in supratentorial and brainstem stroke patients who presented with dysphagia showed that stroke patients had either unilateral or bilateral laryngopharyngeal sensory deficits.²⁵ These sensory deficits were significantly greater than in age-matched controls, and thus these studies provide evidence that impairment of airway protective capacity contributes to dysphagia after stroke. The point of these studies is that in patients with swallowing problems, attention must be paid to how patients sense the food in the upper aerodigestive tract and to how food moves from the lips into the esophagus. Without a precise understanding of patients’ ability to sense the food bolus, clinicians can only guess, at best, if patients can swallow safely.