Читать книгу The Esophagus - Группа авторов - Страница 83

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.

In patients with an inadequate deglutitive glottal closure mechanism, such as seen in patients with Parkinson’s disease or amyotrophic lateral sclerosis, the deglutitive airway closure could be augmented by injection of a non‐absorbable material such as Teflon [32, 83, 84] into the lateral thyroarytenoid muscle. These injections will result in bulk formation at the injection site and displace the true cord in a fixed position toward the midline, facilitating glottal closure during swallowing, since the adduction of the functioning cord will result in contact of the two cords and closure of the introitus of the trachea. Teflon injection into the cords has also been successfully used to prevent aspiration in patients with various types of vocal cord paralysis, due to dysfunction of the recurrent laryngeal and/or superior laryngeal nerve as a result of various central nervous system, surgical, or inflammatory disorders [85, 86].