Читать книгу The Esophagus - Группа авторов - Страница 80

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.