Introduction
The pharyngeal pouch is formed as a herniation of the pharyngeal mucosa through the potential weakness at Killian's triangle, between the transverse fibres of the cricopharyngeal sphincter and the inferior constrictor muscles.Reference Killian1 Most commonly, pharyngeal diverticulae are posterior. There is a potential space between the concavity of the cervical oesophagus and the laterally located left carotid artery, which may account for diverticulae most commonly being seen to the left side of the neck.Reference Shaker, Postma, Belafsky and Easterling2 Interestingly, it has been reported that pharyngeal pouches are associated with opposite handedness of the patients.Reference Stafford, Moore-Gillon and McKelvie3 There is a male predominance. Affected patients, who are often elderly, typically present with dysphagia, chronic cough, regurgitation, aspiration and weight loss.
Abraham Ludlow first described the pharyngeal pouch, in 1769, as a ‘preternatural dilatation of, and bag formed in, the pharynx’.Reference Ludlow4 Similar anomalies were published in Italy and Germany in the late eighteenth century with many more pathologists attempting to define the condition. However, it was a century later, in 1877, that the first detailed case series of 34 patients was reported by Fredrick Albert Zenker and Von Ziemssen, hence the eponym Zenker's diverticulum.Reference Zenker, von Ziemssen and Von Ziemssen5
Pathophysiology
There is no clear pathological mechanism for development of the pharyngeal pouch, but several theories have been postulated. In 1877, Zenker and Von Ziemssen described traction and pulsion diverticulae, and stated that the formation of the pulsion pouch was due to ‘forces within the lumen acting against a restriction’.Reference Zenker, von Ziemssen and Von Ziemssen5 They attributed this restriction to catarrh of the mucosa and reactive thickening of the wall as a result of retained food. Many other older advocates agreed with this ‘foreign body theory’, including Ludlow, who reported identifying a cherry stone in one pouch.Reference Ludlow4
Neck pathologies, such as goitre, congenital strictures, or ossification of the laryngeal cartilage in elderly males, could predispose to development of a diverticula,Reference Westrin, Ergun and Carlsoo6 and one theory suggests trauma could be a precipitant (Fridberg (1867), dissertation).
In 1816, Sir Charles Bell was the first to propose that a pouch developed from the combination of muscle inco-ordination and a pre-existing anatomical area of weakness.Reference Bell7 Killian, in 1908, clarified the anatomical site of origin as between the inferior pharyngeal constrictor muscles and the cricopharyngeus.Reference Killian8 An article by Bensaude et al., in 1922, gave a classification for diverticulae of the cervical region.Reference Bensaude, Gregoire and Guenaux9
In order to better understand the pathophysiology of the pharyngeal pouch, a combination of endoscopic, radiological and manometric studies have been used to assess the oesophageal motor function. The cricopharyngeus muscle forms the upper oesophageal sphincter (UOS) and is important for maintaining tone. The cricopharyngeus is attached posteriorly to the cervical vertebra. Dohlman and Mattsson proposed that mobilisation of this posterior attachment could cause development of the pouch.Reference Dohlman and Mattsson10 A few investigators noted failure of relaxation of the UOS,Reference Cross, Johnson and Gerein11 with some describing it as cricopharyngeus spasmReference Kelly12 and others defining it as an achalasia.Reference Asherson13, Reference Sutherland14 Jackson and Shallow observed endoscopically, and Holmgren confirmed radiologically, that the cricopharyngeus muscle could be the functional abnormality responsible for the genesis of the pouch.Reference Holmgren15, Reference Jackson and Shallow16 Belsey attributed the failure of sphincter relaxation to be the primary problem only in small pouches.Reference Belsey17 A few studies noted inco-ordination between pharyngeal contractions and UOS relaxation, attributing this to premature UOS closure. Following cricopharyngeus myotomy, the resting pressure decreased, but inco-ordination persisted.Reference Ellis, Schlegel, Lynch and Payne18–Reference Fulp and Castell20 Some found no inco-ordination,Reference Fulp and Castell20, Reference Knuff, Benjamin and Castell21 whilst Lichter found premature closure with associated relaxation of the UOS.Reference Lichter22
The most widely held concept of the pharyngeal pouch, almost one hundred years after it was first described, is that of inadequate opening of the UOS but with normal relaxation. Pressure increases can encourage pharyngeal mucosa to herniate through a potentially weak site. This concept has been endorsed by histological studies that showed the presence of inflammation and fibrosis of the cricopharyngeus.Reference Cook, Gabb, Panagopoulos, Jamieson, Dodds and Dent23, Reference Cook, Blumbergs, Cash, Jamieson and Shearman24
There are a few reports of congenital pharyngeal pouch and family history suggesting a larger Killian's triangle, although pharyngeal pouch is generally accepted as an acquired condition.Reference Groves25, Reference Bjork26 Van Overbeek suggested that the relatively high prevalence in North European populations is because of their long necks in comparison to Asians.Reference van Overbeek27, Reference van Overbeek28
Gastroesophageal reflux and pharyngeal pouch development has been studied.Reference Feussner and Siewert29–Reference Resouly, Braat, Jackson and Evans32 Acid reflux is thought to cause altered motility of the UOS and elevated resting tone of the cricopharyngeus, with subsequent development of a pouch due to muscular inco-ordination.Reference Westrin, Ergun and Carlsoo6 Acid reflux may induce longitudinal oesophageal shortening, thus increasing intra-oesophageal pressures.Reference Sasaki, Ross and Hundal33
There have been attempts to classify the diverticulum according to size. In the 1990s, van Overbeek and Groote stated that a small pouch was less than one cervical vertebra in size, and a large pouch was greater than three vertebrae.Reference van Overbeek and Groote34 Also in the 1990s, Morton and Bartley stated that a small pouch was less than 2 cm, a medium pouch was 2–4 cm, and a large pouch was more than 4 cm in size.Reference Morton and Bartley35 Prior to this, in 1954, Lahey and Warren's classification was as follows: a pouch of 1–2 cm was considered stage 1, for which they recommended conservative management; stage 2 was an established pouch of more than 2 cm; and stage 3 indicated that compressive symptoms were present.Reference Lahey and Warren36 For stages 2 and 3, they recommended surgical intervention.
Pharyngeal pouch management
A symptomatic pharyngeal pouch typically presents in the sixth and seventh decades of life.Reference Gregoire and Duranceau37 Diagnosis is usually confirmed with barium studies. Treatment is required if the pharyngeal pouch is symptomatic. Some surgeons will operate on a small pouch whilst the patient is younger, as lesions are likely to become larger in time and there is a risk of carcinoma development.Reference Siddiq, Sood and Strachan38
Initial therapeutic efforts began with external drainage. In 1816, Bell suggested draining the diverticulum by establishing a fistula to empty the pouch.Reference Bell7 In 1885, Wheeler (and subsequently Von Bergmann, in 1892) reported the first successful diverticulectomy.Reference Gregoire and Duranceau37 Kocher, in 1892, successfully excised the pouch and primarily closed the wound.Reference Kocher39 In 1896, Girard devised a method of invaginating the pouch into the oesophagus and oversewing it; however, this technique was subsequently disregarded because of a high recurrence rate.Reference Girard40
Diverticulectomy
The first successful diverticulectomy was performed in 1885, but the technique underwent several modifications before it was widely accepted. Initially morbidity and mortality were high because of the occurrence of uncontrolled pharyngocutaneous salivary fistula.
In 1909, Goldmann reported the first successful two-stage procedure devised to avoid this catastrophic complication.Reference Goldmann41 Firstly, the pouch was anchored high up in the neck, freed from the cricopharyngeus muscle. Secondly, the pouch was excised, one week later. Lahey and Warren, who reported on the first large series of 365 patients, found excellent outcomes for the two-stage procedure, with a mortality rate of only 2 out of 365.Reference Lahey and Warren36
The difficulty of employing the two-stage technique on this elderly patient group with their co-morbidities meant that by the 1950s almost all were using a one-stage procedure as proposed by Sweet.Reference Sweet42
The advent of operative antibiotic cover, improved anaesthetics and better post-operative care all accounted for the improved outcomes found by Payne, who reported a mortality rate of only 1.2 per cent.Reference Payne43
Diverticulectomy has the advantage of eliminating the risk of carcinoma; however, possible complications include wound infection, anastomotic leakage and resultant acute mediastinitis, fistula formation, haematoma, surgical emphysema, and vocal fold paralysis.Reference Feeley, Righi, Weisberger, Hanmaker, Spahn and Radpour44
In the modern era, the use of staplers for closure has further reduced complication rates.Reference Busaba, Ishoo and Kieff45
Diverticulopexy
In 1912, Schmid described anchoring of the pouch fundus high up in the neck to permit dependent drainage and prevent the collection of debris.Reference Schmid46 Later, this procedure became part of many two-stage procedures, along with cricopharyngeal myotomy. Konowitz and Biller recommended this technique for high-risk patients.Reference Konowitz and Biller47 The success with this procedure led to Laccourreye et al. recommending it for all patients.Reference Laccourreye, Menard, Cauchois, Huart, Jouffre and Brasnu48 This procedure can occasionally cause development of a caudally extending diverticulum; in addition, the pouch is not removed and could develop carcinoma.
Cricopharyngeal myotomy
A better appreciation of the role of the cricopharyngeus in the aetiopathogenesis of the pouch prompted the use of cricopharyngeal myotomy as a treatment, with the first report in 1958 by Harrison.Reference Harrison49 However, in 1962, Sutherland suggested that dilatation alone (as advocated by NegusReference Negus50), did not provide uniform symptomatic relief and proposed myotomy alone as the treatment for small pouches.Reference Sutherland14 Zuckerbraun and Bahna, in 1979, also proposed using this approach alone for the elderly population.Reference Zuckerbraun and Bahna51
Myotomy was attractive as it avoided the complications of more extensive surgery, and allowed quicker recovery. However, Payne and King reported a recurrence rate of 22 per cent, and persistence of symptoms was common.Reference Payne and King52
There was controversy regarding the optimal length of the myotomy, but various studies recommended a range from 2–5 cm.Reference Lerut, van Raemdonck, Guelinckx, Dom and Geboes53 For very small diverticulae, the marsupialised diverticulum often disappears after myotomy alone.Reference Simić, Radovanović, Stojakov, Bjelović, Kotarac and Sabljak54
Combination procedures
Cricopharyngeal myotomy can be combined with other procedures, such as diverticulectomy, diverticulopexy or inversion. Belsey recommended cricopharyngeus myotomy with one-stage diverticulectomy to treat small pouches.Reference Belsey17 The findings of a series reported by Lerut et al. supported this.Reference Lerut, van Raemdonck, Guelinckx, Dom and Geboes53
Invagination or inversion of the pouch was used to treat small- and medium-sized pouches. Bowdler and Stell reported less operative time and fewer post-operative complications in comparison with other open procedures.Reference Bowdler and Stell55
Diverticulopexy with cricopharyngeus myotomy where the diverticulum is first inverted and sutured to the pre-vertebral or posterior pharyngeal fascia is preferred by some surgeons for older patients with large pouches who cannot tolerate diverticulectomy.Reference Simić, Radovanović, Stojakov, Bjelović, Kotarac and Sabljak54 This technique also avoids septic complications of mucosal breach.Reference Morton and Bartley35
Inversion diverticulectomy or diverticulopexy alone are no longer acceptable, particularly for larger pouches, because of the high rate of recurrence in the long term without cricopharyngeus myotomy.Reference Gutschow, Hamoir, Rombaux, Otte, Goncette and Collard56
In 2013, Bizzotto et al. reviewed the literature and found that most studies of open approaches were retrospective.Reference Bizzotto, Iacoini, Landi and Costamagna57 However, it was revealed, generally, that: small symptomatic pouches (1 cm in size) could be well treated by myotomy alone; moderately sized diverticulae (1–4 cm) could be treated with myotomy, with suspension or inversion; and larger pouches warranted diverticulectomy with myotomy.Reference Aly, Devitt and Jamieson58 Patients are typically given antibiotic therapy peri-operatively.Reference Mantsopoulos, Psychogios, Künzel, Zenk, Iro and Koch59
Endoscopic techniques – cautery and laser
The endoscopic approach to management of the pharyngeal pouch was originally described by Mosher (1917), then Imperatori (1927), followed by Seiffert (1932); however, the approach was unpopular because of high mortality rates, with the risk of mediastinitis.Reference Dohlman and Mattsson60, Reference Von Doersten and Byl61
Cautery was introduced, in 1960, by Dohlman and Mattsson, who published on their series of 100 patients, reporting good results using a modified rigid oesophagoscope.Reference Dohlman and Mattsson60 In Dohlman's technique, or endoscopic diverticulotomy, the septum is divided using electrocautery.
The endoscopic approach did not gain popularity until technology had evolved significantly, with the arrival of better visualisation techniques through the use of microscopes, optic fibres and better methods of surgical division.
Gastroenterologists used flexible endoscopes with monopolar biopsy forceps to accomplish the incision, whilst Hashiba et al. used a needle papillotome.Reference Hashiba, de Paula, da Silva, Cappellanes, Moribe and Castillo62
Argon plasma coagulation and division of the tissue has also been found to be feasible using endoscopic techniques.Reference Rabenstein, May, Michel, Manner, Pech and Gossner63 In 1982, van Overbeek and colleagues reported their experience of treating patients initially using diathermy and, in 1984, carbon dioxide (CO2) laser to divide the common wall.Reference van Overbeek, Hoeksema and Edens64 They concluded that CO2 laser has the added advantage of better visualisation and more precise, controlled myotomy, and reported good results in 646 patients.Reference van Overbeek28 It was considered useful for small pouches when stapling is impossible to transect the common wall. Laser diverticulotomy can also be achieved using a potassium-titanyl-phosphate 532 nm laser, as employed by Kuhn and Bent.Reference Kuhn and Bent65 A recent retrospective single-centre review from 2001 to 2011 showed a favourable outcome when compared to other studies of patients treated with laser and staple diverticulotomy, with 87 per cent symptom improvement at six weeks and a 2.6 per cent complication rate.Reference Shekhar, Kelly and Watson66
Endoscopic stapling
The more recent availability of linear stapling devices used in laparoscopic surgery has been helpful in endoscopic management of the pharyngeal pouch. In 1993, both Collard et al. in BelgiumReference Collard, Otte and Kestens67 and Martin-Hirsch et al. in EnglandReference Martin-Hirsch and Newbegin68 described the use of these when introduced through a rigid diverticuloscope in a single-stage procedure. The authors reported better haemostasis and fewer anastomotic leaks. There is lower risk of perforation, and avoidance of thermal damage to the recurrent laryngeal nerve. The technique has been modified by a multitude of different investigators.
Scher and Richtsmeier from the USA published on the first series in which this endoscopic stapling technique was utilised.Reference Scher and Richtsmeier69 Technical difficulties have been reported in patients with small or distal diverticulae, or a thick bar, and there are associated problems with the positioning of the stapler.Reference Koay and Bates70, Reference Thaler, Weber, Goldberg and Weinstein71
Endoscopic methods have been proposed as a safer alternative for treating recurrences. Koay and Bates found improved symptoms, without any increase in morbidity.Reference Koay and Bates70 Many studies have confirmed that open and endoscopic approaches are equally as effective. Nevertheless, there are lower rates of complications of vocal fold paralysis, glottis oedema, stricture formation, mediastinitis and fistula formation in endoscopic surgery.Reference Laing, Murthy, Ah-See and Cockburn72 Parker and Misono published a meta-analysis of seven retrospective, uncontrolled studies, which revealed that CO2 laser and stapling procedures had similar complications; however, CO2 laser procedures were associated with more frequent non-dental complications.Reference Parker and Misono73
Long-term follow up of these patients is required to determine the risk of carcinoma in pouches that are not removed.Reference Bradley, Kochaar and Quraishi74
Conclusion
Pharyngeal pouch management has undergone a slow evolution over the twentieth century, despite the exact pathogenesis still remaining ambiguous. Several surgical options for the treatment of pharyngeal pouch exist, and there are risks and benefits of open and endoscopic procedures. Pharyngeal pouch surgery in general is associated with significant morbidity. The 1996/1997 National Confidential Enquiry into Perioperative Deaths in head and neck surgery reported a mortality rate of 1–2 per cent, with the majority of deaths occurring after open procedures.Reference Resouly, Gray, Hoile, Ingram and Sherry75 The report concluded that subspecialisation within otolaryngology departments is appropriate, and that endoscopic techniques are safe, quicker and less invasive.
There remains a lack of good quality, randomised, controlled trials to assess the superiority of one technique over another.Reference Sen, Lowe and Farnan76 This is compounded by a low prevalence and highly concentrated expertise, making randomised, controlled trials relatively infeasible. The open approach was popular throughout the twentieth century and remains popular in many parts of the world today. However, in recent years, endoscopic techniques have gained popularity, with most surgeons opting for stapling as the first line of management for pharyngeal pouch. In 2003, the National Institute for Health and Care Excellence advocated endoscopic stapling of the pharyngeal pouch because of shorter hospital stay and few complications.77 Endoscopic treatment is usually suitable for small to medium diverticula, with large or complex diverticula sometimes benefiting from an open approach, particularly if the patient is young and fit.Reference Bizzotto, Iacoini, Landi and Costamagna57
