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Objective: To review the physiologic basis for normal and abnormal vagal reflexes arising from the pharynx, larynx, and esophagus, as well as the relevance of vagal reflexes to the pathogenesis of such clinically common cardiorespiratory responses as bradycardia, tachycardia, dysrhythmia, coronary angiospasm, bronchospasm, laryngospasm, prolonged apnea, and singultus (hiccups)., Data Sources: Pertinent articles and reviews were identified through a MEDLINE search (April 1966 to October 1991). Older studies and others not identified in the MEDLINE search were found through a manual search of the bibliographies of the retrieved articles., Study Selection: Experimental studies in both humans and animals, as well as case series and single case reports, were selected for evaluation and citation. In instances where a similar phenomenon was described in multiple independent reports, only studies that provided a novel finding or interpretation were cited. More authoritative book chapters and peer-reviewed summaries were also cited in support of commonly accepted principles., Data Extraction and Synthesis: Most of the clinical data are derived from case reports and small case series and are therefore anecdotal; equal weight was given to all such studies. Reports of conflicting observations or interpretations were clearly identified and were cited without exception., Conclusions: Stimulation of the upper aerodigestive tract can lead to clinically significant cardiorespiratory responses. Although the prevalence of and risk factors for such responses have not been established, we suggest that a pharyngeal, a laryngeal, or an esophageal source for abnormal cardiorespiratory responses be sought whenever a detailed clinical evaluation fails to reveal a cause, particularly when there are concurrent symptoms or signs of upper aerodigestive tract disease, such as dysphagia or gastroesophageal reflux.

Simultaneous disorders of the pharynx and esophagus are so frequent that the complete swallowing chain should be examined in all patients with dysphagia. Data are presented to support the concept that such simultaneous disorders represent related phenomena; the mechanism involves changes in cricopharyngeal function seen radiographically as cricopharyngeal prominence. If neurologic disease has been excluded, cricopharyngeal prominence may be the clue to esophageal disease. When cricopharyngeal prominence is found during dynamic imaging of the pharynx, intensive examination of the esophagus and a search for signs of compensation or decompensation in the pharynx should be undertaken.

The technique of dynamic imaging of the pharynx and some supplementary maneuvers which can be tailored to the individual patient's needs are discussed in detail. An approach to the analysis of normal and abnormal swallowing studies is presented.

Under normal circumstances, the act of swallowing adjusts to varying demands of different bolus characteristics and different head and neck postures. When the swallowing mechanism is impaired by disease, adjustment is essential to compensate for the impairment and allow swallowing. Evidence of adjustment can be demonstrated by cineradiography which provides important clues to the presence of underlying disease. When adjustment to disease is inadequate, swallowing decompensates. In this case, gross changes in swallowing performance are evident from clinical evaluation and cineradiography.

Difficulty in swallowing is not an uncommon symptom. Approximately 10,000 persons choke to death every year in the United States, and at least 50% of patients in nursing homes have some difficulty eating or drinking. Dysphagia will become an increasing problem as the population continues to age, as more intensive resuscitative measures are applied, and as more aggressive head and neck surgery is performed. The practicing radiologist should be familiar with the examination technique and interpretation of swallowing studies.

Radiographic evaluation of the passage of a bolus from the mouth through the pharynx into the esophagus is based upon identification of specific anatomical landmarks and the integrated motion accomplished by the oral and pharyngeal muscles during swallowing. Twenty-six muscles and 6 cranial nerves must be coordinated to enable the safe performance of the complex physiological task of transporting liquids and firm food from the mouth into the esophagus. The following discussion and illustrations of pharyngeal anatomy and physiology are pertinent to an understanding of normal swallowing function.

This superbly illustrated article is an invaluable guide to the interpretation of double contrast pharyngograms.