Keywords

Introduction

Achalasia is a primary motility disorder of the esophagus with an incidence of 1 in 100,000 annually. It is best characterized by the existence of both: absence of esophageal peristalsis and failure of relaxation of the lower esophageal sphincter (LES). This is a progressive disease that if left untreated can evolve to a completely nonfunctional megaesophagus. The condition was first described in 1674 by Sir Thomas Willis in connection with a patient who used a cork-tipped whale bone to push food down after each meal. The pathophysiology of the disease remained undefined until 1891 when Mikulicz noted that esophageal obstruction was caused by a physiologic rather than anatomic defect and coined the term “cardiospasm.” Over the past century, the development of fluoroscopy, flexible endoscopy, and more recently high-resolution manometry have transformed our understanding of achalasia. Furthermore, physiologic data now supplements anatomic information to guide therapeutic decision-making. Since defective esophageal peristalsis cannot be corrected, all surgical and endoscopic therapies for achalasia target the non-relaxing lower esophageal sphincter (LES). The introduction of minimally invasive surgery for achalasia in 1991 and the recent introduction of POEM (Per Oral Endoscopic Myotomy) in 2009 have revolutionized the treatment of achalasia and are now the most commonly utilized therapeutic modalities. Furthermore, in the digital era, patients with rare diseases commonly seek information about their condition and direct their own care. Therefore, patients, who in the past might have been told to have pneumatic dilations instead of invasive abdominal or thoracic surgery, now actively seek – often by Internet searches – minimally invasive surgical or endoscopic treatment for their disease.

Treatment: Historical Perspective

Examining the evolution of the surgical management of achalasia dates back to a century ago and allows us to appreciate the evidence and observation-based deductions of many masters of surgery. The methods used during those times are still used as a foundation for current therapy of achalasia. Although there are reports of dilations dating as far back as 1674 and the 1800s, the actual pathophysiology of the disease was not known at that time. The term “cardiospasm” was adopted to describe this condition in 1891 by Mikulicz, reflecting the observation that a true stricture or anatomic obstruction was never seen. Throughout the nineteenth century into the early twentieth century, treatment consisted of dilations, reportedly using something as crude as a whale bone. Advancement of this technique over the years, best characterized by the experience at the Mayo Clinic, gave way to the development of a nonrigid bougie with a hydrostatic dilator mounted on it, which was used in over 800 patients up to early 1932. Complete relief was reported in 70%. At this time, there was very little understanding of the etiology of the disease, but what was for certain was the relief of symptoms (albeit temporary) that was seen in the afflicted [1,2,3,4,5]. This age-old technique, although modernized and perhaps more sophisticated technologically, is still utilized today.

The first surgical techniques were introduced by Mikulicz and involved performing a laparotomy, where gastrostomy was performed and the cardia was dilated with a clamp (Mikulicz operation) or even with digits on the hand (Schloffer and others). Recurrence was noted across the board, but temporary symptom relief was noted and enabled patients to eat. Complications included, but were not limited to, esophageal rupture and death. Reported in 1914, Dr. Arthur Hertz was the first to provide an alternative etiology and coined the term “achalasia” (Greek for “failure to relax”). After performing postmortems on patients with known cardiospasm, he was surprised to find that none revealed sphincter hypertrophy and proposed that, if in fact spasm of the muscle was the cause, there would be hypertrophy. He also proposed that serial rigid dilations would not be possible if spasm was present [1,2,3,4].

With x-ray imaging of these symptomatic patients, a hugely dilated megaesophagus was often seen. In order to address this particular aspect (which we now know as end-stage achalasia), multiple surgical treatments were designed to address the “common objective of straightening out the oesophagus” [6]. One such surgical technique included invagination or intussusception of the dilated esophagus onto itself (held together by interrupted sutures) via a neck incision (Freeman). The patient remained clinically well for years while he was being followed [6]. Herovsky first reported the use of an esophagogastrostomy from an abdominal incision by pulling down redundant esophagus and anastomosing it to the stomach. A number of others performed this operation (as well as modifications of it, i.e., anastomosing to first part of small bowel) in the following years, including Maingot, DeBakey, and Ochsner. Although immediate relief of symptoms was seen, patients were plagued by severe regurgitation and reflux [1, 4, 6]. Esophageal plication was also undertaken in order to address the megaesophagus. Esophageal plication, first reported by Reisinger in 1907 but modified and performed by many others, involved exposure of the esophagus through the posterior mediastinum or transpleurally and then excision of a vertical strip of the dilated esophagus 2–3 cm wide, with the subsequent esophageal re-approximation. Modifications include plication only without excision as well. Results were not favorable as this procedure did not address the cause of the problem [1, 4].

Establishment of the Myotomy and Fundoplication

In 1910, the first “cardioplasty” was performed by Wendel. It is reported that an anterior vertical incision was made on the cardia of the stomach and subsequently sutured transversely with excellent clinical outcome. A few years later in 1914, Heller described a more extensive cardioplasty, in which both an anterior and posterior extramucosal cardioplasty was performed transabdominally by dividing the peritoneum at the hiatus and pulling down the esophagus into the abdomen for exposure. This operation was well-accepted in Europe at the time. Other surgeons were performing this procedure and modifying it as well [1, 4, 7, 8]. Heller’s operation was endorsed by many, and the general opinion on the matter is well-characterized in Maingot’s words: “Oesophagocardiomyotomy is, in my opinion, worthy of a more general adoption, as it is a simple and safe operation, the technique is readily mastered, and the immediate and late results are most gratifying. Furthermore, these statements are confirmed by the excellent results obtained” [7]. This operation, revolutionary at the time, remains the foundation for what has become the gold standard for surgical treatment of achalasia today. The most common modifications included performing either a posterior or anterior myotomy (not both), with excellent symptom relief for both methods.

Although this procedure was quite successful in the treatment of achalasia over the next few decades, there was one resulting side effect: reflux esophagitis. In 1956, Rudolph Nissen described a fundoplication for the treatment of reflux, and in 1962, Dor proposed an operation that essentially addressed both achalasia and the resulting reflux esophagitis that would be encountered after surgical treatment of achalasia. It was a hybrid of the Heller myotomy and Nissen fundoplication and is commonly known as the anterior fundoplication. A transabdominal approach was undertaken, and an anterior myotomy 10 cm in length, which extended 5 cm onto the anterior wall of the stomach, was performed. The Dor fundoplication consisted of suturing the left side of the myotomy to the anterior wall of the stomach, and then the stomach was folded over to the right side of the myotomy and secured with sutures [9]. The Toupet fundoplication was also first reported around the same time but was not readily implemented until many years later [1]. The question of whether or not a fundoplication is required is a controversy that would be carried on for many years. This, of course, was followed by the next considerable discussion: which fundoplication is best?

The Heller myotomy with Dor fundoplication was widely accepted as the standard of care for achalasia. The first large case series (100 patients) reporting on long-term results of this surgical treatment (mean follow-up of almost 7 years) was published in 1988 by Csendes et al. and revealed good to excellent clinical outcomes in over 95% and objective reflux in 19% of patients. Csendes et al. performed an anterior myotomy 6 cm in length, with only 5–10 mm extension onto the stomach [10]. In 1992, Bonavina et al. published their results (median follow-up, 5.3 years) on over 200 patients in which a 10 cm long anterior myotomy (8 cm on esophagus, 2 cm onto the stomach) plus Dor fundoplication was performed. Ninety-four percent had good to excellent clinical outcomes reported, and 9% had abnormal acid exposure as determined by esophageal pH monitoring [11]. The difference in the length of the myotomy and how much is extended onto the stomach as portrayed between these two studies represents the beginning of a long-standing discussion in attempts to standardize the surgical technique. Further complicating this discussion was the fact that the majority of achalasia patients were treated surgically by thoracic surgeons who performed transthoracic rather than transabdominal myotomies. Addressing the question of whether a fundoplication is needed or not, a literature review of just over 5000 patients was analyzed by Andreollo et al., which concluded that a fundoplication was not necessary when Heller myotomy was performed through the chest vs. the abdomen [12]. This group postulated that the abdominal approach (including both open and laparoscopic) required mobilizing the phrenoesophageal ligament, which in turn disrupted the normal anti-reflux mechanism of the GE junction, thereby increasing postoperative reflux.

In the early 1990s, minimally invasive techniques were gaining acceptance in the surgical treatment of foregut disease. Cuschieri was the first to perform a laparoscopic Heller myotomy (LHM) in 1991 [13]. In the United States, Pellegrini performed the first laparoscopic myotomies, which were actually reoperations for insufficient thoracoscopic myotomies [14].

Comparison of the thoracoscopic vs. laparoscopic technique for Heller myotomy (no anti-reflux procedure for thoracoscopic, Dor fundoplication for laparoscopic) revealed faster recovery for patients in the laparoscopic group due to obvious drawbacks of entering the thoracic cavity for surgery, and a higher percentage of patients with abnormal acid exposure when objectively measured was seen in the thoracoscopic group [15]. Bonavina et al. was the first to report the feasibility and safety of laparoscopic Heller myotomy plus Dor fundoplication in 1995 [16], and by the end of the 1990s, the laparoscopic technique for the treatment of achalasia was the new gold standard.

As alluded to before, controversy remained about the length of myotomy required for adequate symptom relief. Patients who underwent standard Heller (1–2 cm extension of myotomy onto gastric wall) with Dor fundoplication and those that underwent “extended” myotomy (defined as 3 cm onto the stomach) with Toupet were compared, and relief from dysphagia was more prominent in the extended myotomy group [17]. This study and others have established the current practice today to ensure extension of the anterior myotomy well past the gastroesophageal junction.

Furthermore, most Heller myotomies today are combined with an anti-reflux procedure. A randomized control trial comparing Heller with and without Dor fundoplication found that the incidence of postoperative reflux measured by 24-h pH monitoring was 9% vs. 48% in those with and without fundoplication, respectively [18]. A meta-analysis by Campos et al. (2009) looking at all publications that reported postoperative 24-h pH monitoring confirms the higher rate of distal esophageal reflux (41.5%) without fundoplication as compared with 14.5% with fundoplication. As expected, incidence of postoperative reflux symptoms was observed in 31.5% after LHM without partial fundoplication vs. 9% in those with fundoplication [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51]. Rawlings et al. compared Dor and Toupet after myotomy in a multicenter randomized control trial and found no significant difference in postoperative reflux and relief from dysphagia [52]. When confronted with a sigmoid-type esophagus and presumed nonexistent esophageal peristalsis in late- to end-stage achalasia, a fundoplication may be omitted as even a partial wrap can exacerbate dysphagia despite myotomy. A full Nissen fundoplication has been abandoned as the appropriate anti-reflux procedure as the incidence of dysphagia with Nissen proves to be unacceptably high vs. a partial wrap [53, 54].

Laparoscopic Heller Myotomy Outcomes

Clinical outcomes of laparoscopic Heller myotomy (LHM) with partial fundoplication have withstood the test of time. Success has been measured by both subjective resolution of symptoms using validated metrics [i.e., Eckardt score, Quality of Life in Reflux and Dyspepsia (QOLRAD), and Gastroesophageal Reflux Disease-Health-Related Quality of Life (GERD-HRQL), among others] and objective measurement utilizing manometry, pH monitoring, and upper endoscopy. Significant palliation of dysphagia was recorded in 89% (79–100%). Improvement of dysphagia remained the same between those with and without an anti-reflux procedure. In a meta-analysis encompassing over 3000 patients by Campos et al., rate of any complication was 6% and mortality was 0.1% (3 patients). Specifically, rate of mucosal perforation is 6.9%, but the clinical significance of perforation is 0.7% as most are recognized intraoperatively and immediately closed without any postoperative ramifications [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51, 54, 55]. In those studies where postoperative 24-h pH monitoring was performed, 14.5% (0–44%) showed evidence of distal esophageal reflux. Those with symptomatic reflux represented a smaller percentage at 8.8% in those with a fundoplication [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51].

Role of Robotic Surgery in the Treatment of Achalasia

Robotic surgery has been evaluated for nearly all aspects of gastrointestinal surgery. The robotic platform has been shown to be safe in patients undergoing Heller myotomy in multiple studies. The enhanced 3D view has been attributed to decreased incidence of intraoperative perforations of the esophagus, although the clinical outcomes are largely the same as compared with laparoscopic surgery. The significant cost, longer operating times, and limited availability are still barriers to widespread acceptance of the robotic platform for the surgical treatment of achalasia [56,57,58,59,60,61,62,63]; furthermore, perforations are in fact extremely uncommon with conventional laparoscopic Heller myotomy when performed by specialist surgeons [64].

Per Oral Endoscopic Myotomy (POEM)

In the continual pursuit for less invasive means of intervention, Inoue developed the POEM procedure and was the first to perform the endoscopic myotomy in patients with achalasia. This innovative endoscopic technique is outlined in detail by Inoue et al. [65], but in brief, it involves creation of a submucosal tunnel, dissection of the circular muscle fibers starting at 3 cm distal to the mucosal entry and 7 cm proximal to the gastroesophageal junction (GEJ) and extending to 2 cm past the GEJ, and closure of the mucosal entry site. In his first publication reporting the initial results, the patients had excellent clinical outcomes (improved dysphagia in 100%) and a significant reduction in LES pressure, with no serious complications recorded [65]. Since the introduction of the POEM procedure, it has been performed with increasing frequency. Subsequent studies have confirmed successful clinical outcomes using subjective metrics and range from 89% to 100% [55, 66,67,68,69,70]. Furthermore, this success rate remains high at 3-year follow-up, which is the longest reported to date [67]. Comparison with LHM reveals that clinical outcomes are similar between the two procedures at 6-month follow-up.

As there is no anti-reflux procedure performed with POEM, postoperative reflux has been a major concern. Esophagitis seen on postoperative endoscopy has been reported to occur in the range of 46–64.7% in short-term follow-up [55, 66,67,68,69,70]. Symptomatic reflux symptoms were seen in 21% at 3 year follow-up [67].

Conclusion

Advances in endoscopic and diagnostic techniques greatly enhanced the understanding of achalasia during the past century. Concurrently, new surgical modalities such as laparoscopic and endoluminal myotomies were developed that revolutionized the treatment of achalasia. Laparoscopic Heller myotomy and POEM are highly effective and have a lower perforation rates than the prior therapies such as pneumatic dilation that dominated in the twentieth century. Internet-savvy patients currently seek the least invasive methods for treatment in order to minimize pain and recovery time. Time will tell if the long-term results of POEM are equivalent to LHM and clarify the significance (if any) of increased esophageal acid exposure that has been observed in POEM patients.