Surgical management of achalasia

Abstract Esophageal achalasia is a primary esophageal motility disorder characterized by lack of peristalsis and by incomplete or absent relaxation of the lower esophageal sphincter in response to swallowing. The cause of the disease is unknown. The goal of treatment is to eliminate the functional outflow obstruction at the level of the gastroesophageal junction, therefore allowing emptying of the esophagus into the stomach. They include the laparoscopic Heller myotomy with partial fundoplication, pneumatic dilatation, and peroral endoscopic myotomy. Esophagectomy is considered as a last resort for patients who have failed prior therapeutic attempts. In this evidence and experience‐based review, we will illustrate the technique and results of the surgical treatment of esophageal achalasia and compare it to the other available treatment modalities.


| INTRODUC TI ON
Esophageal achalasia is a rare disease that affects approximately one in 100 000 people, regardless of gender or race. However, in some geographical locations such as Brazil, it is much more common in connection to the high prevalence of Chagas disease. 1 The incidence of achalasia increases with patient age. 2 In addition, it seems that the prevalence of this disease is increasing, probably due to improvements in diagnostic modalities. 3 In normal conditions, the lower esophageal sphincter (LES) relaxes in response to swallowing. This physiological mechanism is dependent on neurogenic control of the esophagus and LES through the myenteric plexus, combining excitatory acetylcholine neurons, inhibitor nitric oxide, and VIP neurons. Idiopathic achalasia is due to the degeneration of inhibitory neurons, which are involved in the relaxation of LES. As a result, the LES does not relax properly in response to swallowing, and it is often hypertensive. In addition, there is a lack of esophageal peristalsis.
The lack of peristalsis and the impaired LES relaxation impair the transit of the food bolus from the esophagus into the stomach, leading eventually to dilatation of the esophageal body. Almost every patient experiences dysphagia, which often leads to weight loss. Regurgitation of undigested food is also a common ailment, and may cause complications such as hoarseness, coughing, wheezing, and pneumonia. Up to 50% of patients with achalasia also experience heartburn, which is caused by fermentation of retained food in the esophagus. Chest discomfort or pain can also occur, and they are caused by esophageal distension, which usually increases while eating. 4 The severity of achalasia symptoms is evaluated using the Eckardt score.

| PREOPER ATIVE WORK-UP
A comprehensive evaluation of every patient should be carried out to confirm the initial diagnosis suggested by the symptoms, and should include: esophagogastroduodenoscopy (EGD), barium swallow, esophageal manometry, and in some cases ambulatory 24-hour pH monitoring.
Usually, the evaluation begins with an EGD to exclude other causes of dysphagia such as a peptic stricture or a tumor. Typical findings are esophageal dilation and presence of retained food.
Sometimes candidiasis of the esophageal mucosa is present. It is worth mentioning that gastroesophageal junction cancer infiltrating the LES may mimic achalasia. This misleading condition, called pseudo-achalasia, should be ruled out in elderly patients, with short duration of symptoms and marked weight loss. 5 The barium swallow often shows the characteristic "bird beak" sign (narrowing at the level of the gastroesophageal junction), delayed passage of the contrast into the stomach, an air-fluid level, and tertiary contractions of the esophagus.
The gold standard for the diagnosis of achalasia is the high-resolution esophageal manometry (HRM). It enables the measurement of the pressure, length, and relaxation of the lower and upper esophageal sphincters and assessment of esophageal peristalsis. To confirm the diagnosis of achalasia, it is necessary to document lack of esophageal peristalsis and partial or absent LES relaxation. The Chicago classification introduced by Pandolfino 6 and his colleagues distinguishes three types of achalasia. Type I involves aperistalsis and absence of esophageal pressurization; type II is associated with aperistalsis and pan-esophageal pressurization in at least 20% of swallows; and in type III there are premature spastic contractions (distal latency <4.5 seconds) in at least 20% of swallows.
What makes the Chicago classification useful is that it can also help predicting treatment outcome. In fact, many studies have shown higher success rates in patients with type II achalasia. 7,8 It has been speculated that type II achalasia is an initial phase of the disease process with pan-esophageal pressurization, while type I represents a later phase with complete absence of any contraction. 7 Type III achalasia, characterized by premature spastic contractions, is associated with decreased response to surgical treatment. 7 It is speculated that it may represent a recognizably different pathological process which is not a part of the progression from type II to type I achalasia, rather being a variant of distal esophageal spasm which involves the LES. 7 Ambulatory pH monitoring is not necessary in the work-up of patients with achalasia. It should be performed only in patients with heartburn and dysphagia who are considered to have gastroesophageal reflux refractory to medical treatment. In these patients, this test will distinguish GERD from achalasia. 9 Interestingly, up to 50% of patients who end up having a diagnosis of achalasia have been treated for prolonged periods of time with proton pump inhibitors on the assumption that abnormal reflux was present. 10 The pH monitoring study should also be performed after treatment to rule out pathologic gastroesophageal reflux (GER), which is often asymptomatic. 11 In patients who are asymptomatic, particularly if young, we do prescribe acid-reducing medications. In patients found to have erosive esophagitis, we also prescribe acid-reducing medications.

| Evolution of surgery for esophageal achalasia
In 1914, the first transabdominal extramucosal cardioplasty was described by Heller. He performed the myotomy both on the anterior and posterior walls of the cardia. 12 Groeneveldt and Zaaijer simplified the procedure by performing one myotomy only. 13 In the 1940s and 1950s, the transabdominal approach was the most commonly used, while few surgeons favored a left trans-thoracic approach. 14 Until the 1960s, the focus of treatment was on the relief of the dysphagia by the myotomy and no consideration was given to the possibility of post-myotomy reflux. In 1956, Nissen popularized a 360-degree fundoplication to control gastroesophageal reflux and this inspired Dor to propose a 180-degree anterior fundoplication in 1962 that could be added to the myotomy. 15 In 1963, Toupet described a partial posterior fundoplication.
At the beginning of the 1990s, minimally invasive techniques were introduced for the treatment of esophageal diseases. The first laparoscopic cardiomyotomy was performed by Cuschieri in 1991. 16 In 1992, Pellegrini et al described the outcomes of myotomy performed through a left thoracoscopic approach, showing excellent results in about 90% of patients. 17 However, it soon became evident that the procedure led to abnormal gastroesophageal reflux in 60% of patients. 18 Their findings determined a switch to a laparoscopic approach combined with a partial fundoplication. 19 In 1993, Ancona et al reported the technique of a laparoscopic esophageal myotomy and Dor fundoplication developed at the University of Padua. 20 The same year the laparoscopic and open approach were compared showing that, while the outcomes were similar, the minimally invasive approach was associated with a shorter hospital stay, less post-operative discomfort, and faster return to regular activities. 21 Finally, at the end of 20th century, the laparoscopic Heller myotomy (LHM) with fundoplication became the standard of care worldwide (Table 1).

| Laparoscopic Heller myotomy
The treatment of esophageal achalasia is palliative, and it focuses on decreasing the outflow resistance of the GEJ caused by the dysfunctional LES. LHM has been the gold standard therapy for most esophageal achalasia patients. 29,30 SAGES guidelines describe it as a safe and low-risk treatment method for resolving symptoms and improving quality of life. 31 This statement is based on strong evidence showing excellent and durable results. 27,31,32,33 The evolution of achalasia treatment clearly shows that a fundoplication is required to prevent postoperative GERD. 34 Determining whether to perform a total or partial fundoplication was not clear from the start. Topart et al, 38 in a 10-year follow-up evaluation of patients after LHM with total fundoplication, showed that 82% of the patients had recurrence of symptoms. In contrast, Rossetti et al 39  The best type of partial fundoplication (anterior or posterior) after LHM remains undetermined. A multicenter prospective trial by Rawlings et al 26

| Technical aspects of LHM
Our technique for a laparoscopic Heller myotomy has been previously described in the literature. 45 It consists of a 8 cm myotomy extending for 2.5 cm onto the gastric wall and a Dor fundoplication.

| LHM vs other treatment options
Medical therapy and endoscopic botulin injection have limited effect and are indicated for patients who are not fit for other treatment modalities. 46 Other options commonly used are pneumatic dilatation (PD) and the peroral endoscopic myotomy (POEM) ( vs 80.8%). 68 The reason for these different outcomes is probably due to the fact that POEM allows a proximally extended myotomy.
At the end of 2019, the results of a prospective European multicenter randomized trial comparing 109 patients who underwent LHM with 112 patients after POEM were published. 28 At a 3-month follow-up, the rate of reflux esophagitis was 20% after LHM but 57% after POEM. The study indicated the equivalence of the two procedures in terms of symptom relief at 2-year follow-up, which was not surprising as POEM allows an excellent division of the muscle fibers.
Overall, GER remains a major concern for POEM, particularly since there are data showing the onset of denovo Barrett's esophagus and reflux stricture after treatment. 69 In addition, in 2019 the first case of esophageal cancer following POEM was reported. 70 In patients with end stage of achalasia, many experts recommend an esophagectomy as primary treatment. 71,72 However, esophagectomy is associated with longer hospitalization, risk of pneumonia, anastomotic leak, recurrent laryngeal nerve injury, bleeding, chylothorax, and death. 72,73 Considering the satisfactory results of a myotomy, and the high morbidity and mortality associated with an esophagectomy, LHM should always be considered as the first-line treatment option even in end-stage achalasia, reserving esophagectomy for patients who have failed other treatment options.

| FOLLOW-UP
Achalasia patients have an increased risk of squamous cell cancer after treatment, usually 10 to 50 times higher than the general population. 74,75,76 In addition, some studies have shown that adenocarcinoma can occur after treatment due to pathologic gastroesophageal reflux 77,78 . Interestingly the group that designed the 2018 ISDE achalasia guidelines specifically said: "We make no recommendation about routine endoscopy surveillance or endoscopy intervals after any treatment". 79 In our center, we do recommend routine EGD

TA B L E 2 (Continued)
accept. Some insurance companies will allow an EGD only if a patient has recurrent symptoms.

| TRE ATMENT ALG ORITHM FOR ACHAL A S IA MANAG EMENT
POEM and LHM are equally effective and should considered in every patient with achalasia. In our center, we do perform LHM for patients with type I and type II achalasia. These patients are often overweight and have a hiatal hernia so that the addition of a fundoplication allows control of reflux in most patients. In patients with type III achalasia, POEM should be considered as initial treatment. In case of failure, we recommend PD as the second step therapy. If pneumatic dilatation fails, it is reasonable to consider POEM for those who underwent LHM initially and LHM for those after POEM. Esophagectomy should be considered as a last resort for patients with persisting symptoms after failure of other treatment modalities.

D I SCLOS U R E
Conflict of Interests: Authors declare no conflict of interests for this article.