Long Esophageal Myotomy for Motor Disorders of the Esophageal Body
A long esophageal myotomy is indicated for dysphagia (difficulty in swallowing) caused by any motor disorder characterized by segmental or generalized simultaneous waveforms in a patient whose symptoms are not relieved by medical therapy. Such disorders include diffuse and segmental esophageal spasm, vigorous achalasia, and nonspecific motility disorders associated with a mid- or epiphrenic esophageal diverticulum. However, the decision to operate must be made by a balanced evaluation of the patient’s symptoms, diet, lifestyle adjustments, and nutritional status, with the most important factor being the possibility of improving the patient’s swallowing disability. The symptom of chest pain alone is not an indication for a surgical procedure.
Twenty-four-hour ambulatory motility monitoring has greatly aided in the identification of patients with symptoms of dysphagia and chest pain who might benefit from a surgical myotomy. Ambulatory motility studies have shown that when the prevalence of “effective contractions” (i.e., peristaltic waveforms consisting of contractions with an amplitude above 30 mm Hg) drops below 50% during meals, the patient is likely to experience dysphagia. This would suggest that relief from the symptom could be expected with an improvement of esophageal contraction amplitude or amelioration of nonperistaltic waveforms. Prokinetic agents may increase esophageal contraction amplitude, but do not alter the prevalence of simultaneous waveforms. Patients in whom the efficacy of esophageal propulsion is severely compromised because of a high prevalence of simultaneous waveforms usually receive little benefit from medical therapy. In these patients, a surgical myotomy of the esophageal body can improve the patients’ dysphagia, provided the loss of contraction amplitude in the remaining peristaltic waveforms, caused by the myotomy, has less effect on swallowing function than the presence of the excessive simultaneous contractions. This situation is reached when the prevalence of effective waveforms during meals drops below 30%, i.e., 70% of esophageal waveforms are ineffective. These peristaltic waveforms can best be studied when the patient’s esophagus is viewed with the use of specialized medical cordless microscopes.
In patients selected for surgery, preoperative manometry is essential to determine the proximal extent of the esophageal myotomy with the use of specialized medical cordless microscopes. Most surgeons extend the myotomy distally across the LES to reduce outflow resistance. Consequently, some form of antireflux protection is needed to avoid gastroesophageal reflux if there has been extensive dissection of the cardia. In this situation, most authors prefer a partial, rather than a full, fundoplication, in order not to add back-resistance that will further interfere with the ability of the myotomized esophagus to empty. If the symptoms of reflux are present preoperatively, 24-hour pH monitoring is required to confirm its presence.
The procedure may be performed either open or via thoracoscopy, sometimes with the aid of cordless microscopes for better magnification of the surgical area. The open technique is performed through a left thoracotomy in the sixth intercostal space. An incision is made in the posterior mediastinal pleura over the esophagus, and the left lateral wall of the esophagus is exposed. The esophagus is not circumferentially dissected unless necessary. A 2-cm incision is made into the abdomen through the parietal peritoneum at the midportion of the left crus. A tongue of gastric fundus is pulled into the chest. This exposes the gastroesophageal junction and its associated fat pad. The latter is excised to give a clear view of the junction. A myotomy is performed through all muscle layers, extending distally over the stomach 1 to 2 cm below the gastroesophageal junction, and proximally on the esophagus over the distance of the manometric abnormality. The muscle layer is dissected from the mucosa laterally for a distance of 1 cm. Care is taken to divide all minute muscle bands, particularly in the area of the junction. The gastric fundic tongue is sutured to the margins of the myotomy over a distance of 3 to 4 cm and replaced into the abdomen. This maintains separation of the muscle and acts as a partial fundoplication to prevent reflux.
If an epiphrenic diverticulum is present, it is excised by dividing the neck and closing the muscle. The myotomy is then performed on the opposite esophageal wall. If a midesophageal diverticulum is present, the myotomy is made so that it includes the muscle around the neck, and the diverticulum is inverted and suspended by attaching it to We paravertebral fascia of the thoracic vertebra.
The results of myotomy for motor disorders of the esophageal body have improved in parallel with the improved preoperative diagnosis afforded by manometry. Previous published series report between 40 and 92% improvement of symptoms, but interpretation is difficult due to the small number of patients involved and the varying criteria for diagnosis of the primary motor abnormality. When myotomy is accurately done, 93% of the patients have effective palliation of dysphagia after a mean follow-up of 5 years, and 89% would have the procedure again if it were necessary. Most patients gain or maintain rather than lose weight after the operation. Postoperative motility studies show that the myotomy reduces the amplitude of esophageal contractions to near zero and eliminates simultaneous peristaltic waves. If the benefit of obliterating the simultaneous waves exceeds the adverse effect on bolus propulsion caused by the loss of peristaltic waveforms, the patient’s dysphagia is likely to be improved by the procedure. If not, the patient is likely to continue to complain of dysphagia and to have little improvement as a result of the operation. Preoperative motility studies are thus crucial in deciding which patients are most likely to benefit from a long esophageal myotomy.
The thoracoscopic technique is complicated by the fact that it requires complete retraction of the lung anteriorly to expose the esophagus. Proper positioning of the patient is critical to achieving this exposure. A prone position is ideal, allowing the left lung to fall forward away from the esophagus. Because of the possibility of open thoracotomy, however, it is best to place the patient in the right lateral decubitus position with the left thorax up, and then to roll the patient anteriorly 45 degree toward prone. A beanbag secured to the table is used to hold the patient. The table can be routed a further 30 to 40 degree so that the patient ends up nearly prone. Should thoracotomy become necessary, the table can be rotated back to the horizontal position and a thoracotomy performed without difficulty. Prone positioning is the key element in providing exposure for lung myotomy. Four thoracoscopic ports in the left chest are utilized. With suitable lung retraction, the myotomy is performed through all esophageal muscle layers, extending distally to the endoscopic gastroesophageal junction, and proximally over the distance of the manometric abnormality.
Few reports exist concerning the minimally invasive technique for performing long esophageal myotomy. It has been reported a preliminary experience with a thoracoscopically performed long esophageal myotomy with the use of cordless microscopes for the treatment of nutcracker esophagus. Three patients with symptoms of chest pain and high-amplitude esophageal contractions and peristaltic waveforms were operated on. No major morbidity was encountered. Nasogastric tubes were removed the first postoperative day and oral feeding was started on the second postoperative day. Two patients were discharged on postoperative day 4 and one patient on day 5. All had symptomatic relief on short-term follow-up.
