advanced to the level of the epiglottis. On the way toward the epiglottis, attention is given to the presence or absence of blue staining of the retropalatal pharynx, indicative of nasal regurgitation due to abnormalities of the velopharyngeal closure mechanism. This abnormality may be caused by inadequate elevation and posterior movement of the soft palate and uvula. Then the inner aspect of the epiglottis, aryepiglottic fold, posterior commissure, and true vocal cords are examined for the presence or absence of staining. In a study of normal volunteers in our laboratory, only the outer edges of the epiglottis and aryepiglottic fold were stained with blue dye. Endotracheal coloring with blue dye is easily seen, proving aspiration. The patients are then asked to cough once; and, since during cough the laryngeal vestibule remains open, expulsion of blue material from the trachea can be seen and is indicative of aspiration. Following this phase, the presence or absence of residue in the pyriform sinus and vallecula is determined, and overflow of residue into the trachea through the posterior commissure is sought.
Manometry
The use of intraluminal strain gauges for pharyngeal manometry and high‐resolution pharyngoesophageal manometry has resulted in a significant increase in our knowledge about the pharyngeal pressure phenomena, but these modalities remain mainly as research tools, and clinical application at this time is limited to the evaluation of dysphagic patients with primary muscle diseases. An example of these disorders is Kearns–Sayre syndrome, where significant diminution of the pharyngeal peristaltic pressure wave amplitude is the prominent finding [74]. Because the pharynx is radially, as well as axially, an asymmetric cavity, orientation of the pressure transducers needs to be ascertained and preferably similar in all studies to obtain meaningful data. However, with the availability of high‐resolution catheters with circumferential pressure sensors, this limitation has been remedied. Concurrent pharyngeal and UES high‐resolution manometry helps detect discoordination between the UES relaxation and the arrival of pharyngeal peristalsis in the hypopharynx. Use of manometry to evaluate the oral phase in dysphagic patients has generally been unsuccessful, and this modality continues to be used mainly for research purposes.
As discussed previously, normal UES opening requires the existence of normal cricopharyngeal relaxation and distensibility, as well as normal contractile force of the suprahyoid muscles. Traditionally, UES resting tone and deglutitive relaxation have been studied by intraluminal manometry. Because of the orad displacement of the UES during swallowing and its to‐and‐fro movement during breathing, the use of a sleeve sensor, such as the currently available e‐sleeve of the high‐resolution manometric catheter, has been advocated for this purpose. This sensor provides continuous measurement of the UES pressure [75] and records maximal squeeze pressure regardless of the axial sphincter movement along the length of the device. Shorter pressure sensors, either strain gauges or pneumohydraulic side holes, may remain within the sphincter at rest. However, during swallowing, they will drop into the cervical esophagus, due to the upward movement of the sphincter, and record intraesophageal pressure, which may be misinterpreted as UES relaxation.
Differentiating between deglutitive relaxation and opening of the cricopharyngeal muscle by intraluminal manometry is impossible. The sudden intraluminal UES pressure decline during swallowing, commonly referred to as UES relaxation, reflects the effect of (i) cricopharyngeal relaxation and (ii) UES opening of various degrees. Concurrent manometry and fluoroscopy also provide information that is the summation of the two effects of relaxation and opening. For this reason, concurrent manometry, electromyography, and video‐fluoroscopy are essential to differentiate the effects of these phenomena.
A relatively common change in UES morphology, observed during pharyngoesophageal barium studies, is a prominent posterior indentation at the level of the UES; cricopharyngeal bar. Although rarely associated with dysphagia, its observation has been reported in 5% of patients older than 40 years who did not have symptoms [76]. Despite the common notion of spasm or failed relaxation, the pathogenesis of cricopharyngeal bar is not fully known. A study by Dantas et al. has shown a normal resting pressure, as well as normal deglutitive relaxation, in individuals with cricopharyngeal bar [77]. However, the upstream (intrabolus) pressure was found to be higher than that of normal controls. Reduced dimension of UES during passage of barium was also found, suggestive of reduced compliance of the cricopharyngeal muscle.
Ultrasonography
Ultrasound has been successfully used for evaluation of the oral phase of swallowing. Since this modality is non‐invasive and does not disturb the physiology of the oral phase of swallowing, it can be used in addition to videofluoroscopy to evaluate the dysphagic patient. Using this modality, Sonies et al. have described subtle, subclinical changes in the oral phase of swallowing in the elderly [78].
Management
Although only a minority of patients with OPD are amenable to medical/surgical therapy, the majority do require retraining and use of various swallowing maneuvers and techniques to achieve an adequate and safe swallow.
Endoscopic and surgical management
Cricopharyngeal dilatation and myotomy have been performed for a variety of neurogenic and myogenic causes of OPD, with variable results. However, controlled clinical trials and outcome studies are lacking. In general, myotomy yields good results in cricopharyngeal achalasia due to primary cricopharyngeal muscle involvement. The results are less predictable for primary neurogenic causes if other parts of the swallowing apparatus are also involved. The role of myotomy in secondary cricopharyngeal achalasia is controversial, since deglutitive relaxation is present in this group. The rationale for the cricopharyngeal myotomy, which usually is extended to the lower part of the inferior pharyngeal constrictor and upper part of the cervical esophagus, is to eliminate the resistance of the UES against the flow of the swallowed bolus. Under normal conditions, this resistance is eliminated by timely relaxation, followed by opening and timely closure of the UES However, in a variety of conditions, because of discoordination of the UES and pharynx or ineffective pharyngeal function, the UES acts as a relative resistor to the bolus flow. It is in these conditions that cricopharyngeal myotomy may improve pharyngeal bolus transit and reduce aspiration. Endoscopic transmucosal botulinum toxin injection into the cricopharyngeal muscle has been tried in patients with cricopharyngeal achalasia; however, proximity of the injection area and the vocal cords raises special concern about possible respiratory complications. On the other hand, because of the temporary effect of the botulinum toxin, this new technique could potentially be used to select patients who will benefit from cricopharyngeal myotomy.
Vencovsky et al. reported successful resolution of dysphagia after cricopharyngeal myotomy in a patient with acute cricopharyngeal obstruction due to dermatomyositis [79]. Gagic reported excellent results of cricopharyngeal myotomy in patients with Zenker’s diverticulum and idiopathic hypertrophy of the cricopharyngeal muscle, and marked improvement in patients with vagal injuries, amyotrophic lateral sclerosis, and post‐stroke; however, no improvement was achieved in patients with myotonia dystrophica [80]. Two patients developed aspiration pneumonia and respiratory arrest. Logemann has reported that the results of cricopharyngeal myotomy are superior when pathology is mainly in the UES, there are pharyngeal propulsive forces present, and patients are able to close the airway voluntarily [81]. Since the major barrier against pharyngeal regurgitation of gastric acid, namely the UES, is ablated by myotomy, post‐operative pulmonary complications of gastroesophageal reflux should remain a significant concern in patients who undergo cricopharyngeal myotomy. In a report of 253 patients who underwent cricopharyngeal myotomy, one of 15 patients with neurogenic dysphagia developed persistent aspiration requiring a tracheostomy, four of 139 patients with muscular dystrophy died of respiratory distress syndrome and two required a tracheostomy, while none of the 90 patients with Zenker’s diverticulum developed any major respiratory complications [82]. These results suggest the significant role of factors other than myotomy per se, such as abnormal esophageal motility and proximal or pharyngeal reflux in the development of post‐cricopharyngeal myotomy respiratory complications. Documentation of the absence of proximal esophageal and pharyngeal reflux and normal esophageal motility before surgery may help in the decision‐making process.