Introduction

Esophageal diverticulum is a rare condition with an estimated prevalence around 0.02–3% [1] with higher rates in countries with an upper digestive cancer screening policy [2]. The esophagus may harbor diverticula in any portion of the organ. Mid-esophageal diverticula (Rokitansky diverticulum) are today more rare as they are typically associated with tuberculous mediastinal lymph nodes, although esophageal dysmotility has been found in most current cases [3]. Diverticula at the pharyngo-esophageal junction (Zenker’s diverticulum) or at the distal esophagus (epiphrenic diverticulum—ED) are pulsion pseudodiverticula. ED are located in the distal 10 cm of the esophagus and make up 10% of the esophageal diverticula [4].

Esophageal dysmotility is found in the majority of ED [5, 6]. Achalasia is the most frequent associated dysmotility [5, 7], and an ED can be found in 3–7% of patients with achalasia [8]

Clinical presentation

ED can be asymptomatic in 40–60% of the cases [9, 10]. Dysphagia, regurgitation, weight loss, retrosternal pain, heartburn and respiratory complaints are the most common symptoms when present [2, 7, 11, 12]. Clearly these symptoms overlap with the symptoms present in achalasia (or other motility disorder) leading most authors to believe that symptoms are caused by the underlying motility disorder rather than the diverticulum per se, and do not correlate with its size [2, 9, 13].

Diagnosis

The diagnostic workup should always include an upper digestive endoscopy and a barium esophagogram [2, 10].

Upper digestive endoscopy can diagnose the diverticulum and may exclude associated diseases [9] (Fig. 1).

Fig. 1
figure 1

Endoscopic view of a small epiphrenic diverticulum (arrow)

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Barium esophagogram may define the number, size, location, and shape of diverticula. It may also identify rare complications such as fistulae [2, 12], and it can be helpful to identify the underlying motility disorder with findings suggestive of achalasia (bird’s beak sign, esophageal dilatation, contrast retention, and tertiary contractions) [9, 12].

Esophageal manometry may be added to the workup to precisely identify the underlying motor disorder. There are three reasons that might justify not performing a manometry: (1) dysmotility is present in probably all cases [5, 6]; (2) negotiating the lower esophageal sphincter may be difficult by blind intubation during manometry requiring placement guided by endoscopy; and (3) a cardiomyotomy must always be performed irrespective of the type of dysmotility, even when it is not detected such in some cases of diffuse esophageal spasm when the disorder is intermittent.

Ambulatory prolonged esophageal pH monitoring is not necessary since the association of ED and gastroesophageal reflux disease is rare and pseudoreflux may be detected due to food fermentation in the ED [2, 9].

Treatment

Asymptomatic diverticula

In the absence of symptoms in patients without prior history of aspiration and a non-dilated esophagus, ED may be left untreated. Studies that investigated the outcome of untreated diverticula did not find complications, worsening of pre-existing symptoms or change in size over time [14, 15]. Moreover, the burden of the risk of the operation is higher than the risk of complications [16]. The fear of malignant transformation does not justify treatment as the risk is neglectable [1].

Diverticula treatment

Diverticulectomy alone should never be performed. This approach does not take into account the ED pathophysiology that is caused by an underlying motility disorder. Moreover, the technique is associated with higher rate of symptoms persistence [16] and higher rate of leak due to elevated pressure in the esophageal lumen if a myotomy is not performed [2, 6, 7, 16].

Heller's myotomy and diverticulectomy is the classic surgical treatment for ED with achalasia [7]. This approach will treat achalasia and the ED. Classically it was performed through the chest. The advantage of a thoracic approach is an easier dissection of the upper part of the diverticulum, releasing strong adhesions and oversewing the staple line [16,17,18]. However, this route requires single lung ventilation, chest tube placement, and is difficult to add an anti-reflux procedure [13, 18,19,20]. The abdominal approach has several advantages such as a better access to the esophagogastric junction, easier performance of a fundoplication, and lower pulmonary morbidity [7, 13, 18]. Table 1 shows the results for minimally invasive procedures for ED treatment. Myotomy should extend proximally from the upper portion of the diverticular neck to 2 cm below the gastroesophageal junction distally [9, 13] (Fig. 2). Releasing the proximal aspect of the diverticulum from adhesions may be challenging, and placing a Penrose drain around the EGJ can allow good traction to facilitate the dissection [18]. When a diverticulectomy is chosen, the myotomy should be performed on the opposite side of the diverticulum in order to allow a suture line over the staple line, thus reducing the risk of a leak [9, 13, 18] (Fig. 3). A 50–56 F bougie should be placed before stapling the neck of the diverticulum to avoid luminal narrowing [18].

Table 1 Surgical minimally invasive treatment for epiphrenic diverticulum
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Fig. 2
figure 2

Cardiomyotomy if diverticulectomy is not to be performed should be initiated in the upper portion of the diverticular neck and extend distally 2 cm below the gastroesophageal junction

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Fig. 3
figure 3

Cardiomyotomy if diverticulectomy is associated should be performed on the opposite side of the diverticulum in order to allow a suture over the staple line

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Treatment of achalasia only

As mentioned before, recent studies showed that an underlying motility disorder is responsible for most symptoms [6, 21]. This has led some authors to believe that a myotomy alone (without diverticulectomy) could yield satisfactory results [7, 13] and avoid the risk of a staple line leak. A leak occurs in 5–30% of patients, with an average morbidity of 20% and 4% mortality even in experienced hands [16]. In addition, smaller diverticula tend to vanish once a myotomy is performed, while the risk of malignant transformation is negligible [9, 16].

Per-oral endoscopic myotomy (POEM) arose in the last decade and is now considered a safe and effective minimally invasive treatment for achalasia [22]. This technique has been used as treatment for EP [23]. More ingeniously, endoscopists combined this technique with a septotomy in patients with achalasia and ED, named as D-POEM [24, 25]. As for laparoscopic myotomy, POEM alone can relieve symptoms like dysphagia and regurgitation without the need for resection the diverticulum [22, 23] (Table 2). The advantage of this procedure is particularly in spastic disorders such as type III achalasia or diffuse esophageal spasm which require a longer myotomy, safely performed through endoscopy [23]. The main drawback of this technique is the absence of an anti-reflux procedure, leading to gastroesophageal reflux in up to 46% of patients that underwent POEM [26].

Table 2 Endoscopic treatment for epiphrenic diverticula
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Pseudodiverticulum at the myotomy site

Pseudodiverticulum may occur as an outpouching of the mucosa along the myotomy site (either endoscopic or surgical). This condition is rarely discussed although some authors point out a significant incidence between 20 and 70% [27, 28]. Curiously, it occurs even after an anterior fundoplication [28]. Some authors do not attribute symptoms to this finding [29], while other believe this is associated with treatment failure due to persistent obstruction at the esophagogastric junction [28, 30].

Conclusions

Epiphrenic diverticulum is a rare condition whose pathophysiology involves an underlying motility disorder—achalasia in most cases. Symptoms usually include dysphagia, regurgitation, heartburn, and respiratory complaints and correlate with the motility disorder rather than the diverticulum per se. Upper digestive endoscopy and barium esophagogram are needed for the diagnosis—manometry may add useful information but is not imperative for the treatment. Laparoscopic Heller myotomy with a partial fundoplication is the procedure of choice, with satisfactory symptom relief and several advantages over the thoracic approach. Diverticulectomy may be performed in selected patients. POEM and D-POEM are novel techniques, effective and minimally invasive that can be an option for patients unfit for surgery.