reflex, and the laryngeal adductor reflex. All of these protective reflexes are impaired with aging, and the reflexive pharyngeal swallow and pharyngoglottal reflex are impaired with smoking and alcohol [3760–62]. These deficits can predispose to aspiration.
Older adults demonstrate a slower swallowing process, decreased isometric lingual pressure, unchanged deglutitive lingual pressure, decreased UES opening, and decreased functional reserve [63, 64]. As the population ages, the prevalence of swallow difficulties grows, which is evidenced by the 93% increase in Medicare beneficiaries for aspiration pneumonia from 1991 to 1998 [65]. Abnormal UES opening or pharyngeal outflow obstruction may be caused by primary mechanisms, i.e. myogenic or neurogenic, or secondary mechanisms, such as inadequate suprahyoid muscle traction, aging, deconditioning, and stroke. The evaluation and treatment of abnormal UES opening are discussed next.
Evaluation
Physical examination
The evaluation of OPD begins when the patient enters the room, with appearance and gait. A thorough neuromuscular examination is essential as many causes of OPD will have systemic findings. The oropharynx should be inspected for dentition, symmetry, as well as the presence of saliva. Xerostomia is a common cause of OPD in the elderly. This finding should be followed by eye evaluation, joint examination, and a careful history regarding anticholinergic medications and head and neck surgery or radiation. Change in voice such as hoarseness or nasal speech may be observed with nerve dysfunction and soft palate dysfunction, respectively. The neck should be palpated for masses. Before proceeding to a radiologic test or swallow study, it is helpful to ask the patient to perform a dry swallow in the office for visual inspection of movement and symmetry, and with gentle pressure on the thyroid cartilage and hyoid bone. Normal movement is elliptical antero‐superior motion. Abnormal ascent is seen in neurologic disorders.
Laboratory tests
Although no specific laboratory tests are required in the evaluation of OPD, many clinicians obtain a thyroid‐stimulating hormone (TSH) measurement to evaluate for hyperthyroidism [64]. Systemic symptoms may direct the clinician to order other laboratory tests for the evaluation of a myopathy, connective tissue disease, drug toxicity or poisoning, etc.
Dynamic studies
The approach to the OPD patient is evolving. Several modalities are available for the evaluation of OPD patients, including barium studies, pharyngoesophageal high‐resolution manometry, endoscopy, ultrasonography, and scintigraphy. Ongoing intensive research by various disciplines is making the approach to the OPD patient a dynamic and improving phenomenon. Quantitative normalcy data is now available, and study recordings and test substances are more standardized, allowing for inter‐study comparisons. With the advent of digitalization technology, endoscopic and fluoroscopic images are digitized and analyzed using the slow‐motion and frame‐by‐frame movement capability. This technology permits synchronization of several modalities and accurate timing of the events. This synchronization allows determination of the temporal relationship of various events, such as bolus movement and airway closure during oropharyngeal swallowing. Since all the structures of the oropharynx are not adequately seen during swallowing with one single modality, this multi‐system recording is essential for studying the coordination of oropharyngeal swallowing events.
Modified barium swallow
Currently, video‐fluoroscopic recording of a modified barium swallow is the diagnostic modality of choice for initial investigation of the patient with OPD. During this study, recordings of a variety of boluses with different consistencies and volumes are made for subsequent analysis. These recordings may be used subsequently for future comparisons to evaluate progress. This technique provides not only adequate information about the movement of the barium bolus through the aerodigestive tract and documents misdirection of the bolus into the airway, but also vital information about the anatomy and function of the individual anatomic components of the aerodigestive tract involved in swallowing [66, 67]. Additionally, this modality is used to evaluate the effect of various postural and breathing techniques on the efficiency, as well as safety, of swallowing [32, 68]. Normal and abnormal video‐fluoroscopic findings of swallowing have been published extensively [32, 38, 69]. On video‐fluoroscopy, abnormalities of the oral phase of swallowing may manifest themselves as inadequate clearance of the barium bolus from the mouth (leaving a barium residue behind), piece‐meal swallowing due to inadequate tongue function, or difficulty initiating the swallowing sequence due to impaired cognitive or neural function [32]. Patients with difficulty controlling the labial or facial muscles will not be able to hold the barium bolus in their anterior mouth and will end up drooling during swallow. Premature spilling of the oral contents into the pharynx before the pharyngeal phase is activated will catch the airway off guard and may result in pre‐deglutitive aspiration. This abnormality commonly occurs with impaired palatal and/or lingual control.
Abnormalities of the pharyngeal phase of swallowing documented by video‐fluoroscopy include concomitant absent or diminished upward/forward movement of the larynx and hyoid bone, indicating inadequate suprahyoid muscle contraction. This abnormality may be accompanied by entry of barium into the airway beyond the level of the true vocal cords (aspiration). An incompetent velopharyngeal closure mechanism, due to inadequate elevation and/or weak posterior movement of the palate and uvula, may result in regurgitation of the barium into the nasopharynx. This abnormality may develop after stroke, inflammatory disorders of striated muscles, or surgical excisions. Abnormalities of the oral phase of swallowing may or may not be accompanied by abnormalities of the pharyngeal phase of swallowing.
Abnormalities in transport function during oropharyngeal swallowing result in hypopharyngeal residue. Abnormal lingual, pharyngeal, or UES function, singularly or in combination, may be responsible. Unilateral involvement of the pharynx results in ipsilateral post‐deglutitive bulging of the pharyngeal wall and residue on the same side [29, 38].
Misdirection of the barium into the airway may be due to intrinsic abnormalities of the glottal adductor muscles, resulting in an ineffective glottal sphincteric mechanism or lack of coordination between glottal closure and transport function of the oropharynx, which is commonly seen in neurologically impaired patients.
Abnormal opening of the UES during swallowing, seen by video‐fluoroscopy, may be due to lack of or impairment of its relaxation, decreased UES compliance, or inadequate traction by the suprahyoid muscles. Correct diagnosis requires manometric evaluation of the UES for its resting pressure and its swallow‐induced relaxation. Diagnosis of cricopharyngeal achalasia cannot be made solely from its radiographic appearance.
Videoendoscopy
The chronic nature of OPD requires assessment of therapeutic results and progress with repeat video‐fluoroscopic study. Because of the radiation exposure and difficulty in moving some patients to the radiology suite, a videoendoscopic approach to the evaluation of OPD has been developed [70–73]. This technique also allows outpatient/clinic evaluation of dysphagic patients. In this technique, a small‐diameter endoscope, such as a laryngoscope or bronchoscope, is inserted through the nose and positioned at the level of the posterior nares. In this position, the patient is asked to swallow. During this swallow, normal features of the pharyngeal seal – the adduction of the superior constrictor and postero/orad elevation of the palate, seen as a bulging in the nasopharynx – are examined, and then the scope is advanced to the level of the free margin of the epiglottis. At this position, the glottis is clearly seen, and its adduction function is examined by having the patient produce different vowels. Following this, a 5–10 mL water bolus colored with blue food dye is given through the mouth, and the patient is instructed to hold the bolus in the mouth for 20 s. During this time, the back of the tongue is observed video‐endoscopically for the presence or absence of unilateral or bilateral spill or entry of colored water into the airway (pre‐deglutitive aspiration). The presence of spill is seen in patients with abnormalities of the tongue and/or palate control. Following this stage, the scope is withdrawn to the level of the posterior nares, and the patient is asked to