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MMCTS
(February 24, 2009). doi:10.1510/mmcts.2007.002881 Copyright © 2009 European Association for Cardio-thoracic Surgery Procedure Zenker's diverticulumUniversity Hospitals Leuven, Belgium * Corresponding author: Department of Thoracic Surgery, Herestraat 49, 3000 Leuven, Belgium. Tel.: +32-16-346820; fax: +32-16-346821. toni.lerut{at}uzleuven.be
The cricopharyngeal diverticulum or Zenker's diverticulum is the most frequent type of diverticulum of the upper gastrointestinal tract. It occurs mostly in elderly patients. The predominant symptoms are dysphagia and regurgitation which may result in malnutrition and aspiration pneumonia, the latter eventually being life threatening. The underlying cause of Zenker's diverticulum is a dysfunction of the cricopharyngeal muscle and the upper esophageal sphincter, the most common finding being a decreased compliance. The treatment consists in a myotomy of the upper esophageal sphincter and cricopharyngeal muscle combined with a diverticulopexy or diverticulectomy. This procedure is performed via a limited left cervicotomy. Results are excellent to very good in 94% of the patients in our own experience.
Key Words: Cricopharyngeal muscle • Extramucosal myotomy and diverticulopexy • Pharyngo-esophageal diverticulum • Upper esophageal sphincter • Zenker's diverticulum
Pharyngo-esophageal diverticulum was described for the first time as a pathologic entity by Ludlow in 1679 [1]. However, it was Zenker who gave his name to this condition through his publication in 1877 reporting a series of 27 patients [2]. Already at that time Zenker presumed the pouch being the consequence of ‘forces within the lumen acting against a restriction’ a hypothesis which is close to modern understanding of pathogenesis indeed and remarkable since both endoscopy and X-ray had yet to be invented. However, the mechanistic compression theory as a cause of symptoms would prevail until far into the 20th century dominating the therapeutic strategy as well (diverticulectomy). Only during the last decennia of the 20th century, thanks to the new developments in imaging, endoscopy, manometry and manofluography, better insights into the pathogenesis of Zenker's diverticulum came through resulting in fundamental changes in the therapeutic strategy (myotomy of the cricopharyngeal muscle).
Zenker's diverticulum is defined as a blow out of the mucosa through a so-called locus minoris resistensiae on the posterior wall at the transition zone between the hypopharynx and the esophagus (Killian's triangle) [3] (Schematic 1).
The exact cause of the development of a Zenker diverticulum still remains unclear. It is accepted that it is to be considered as a pulsion diverticulum secondary to a disturbance in the function of the cricopharyngeal muscle and the so-called upper esophageal sphincter zone as defined on manometry. The most important physiopathologic finding seems to be a decreased compliance, i.e. inadequate opening of the cricopharyngeal muscle at the time of the passage of the alimentary bolus. This will result in an increased intrabolus pressure in the transition zone between the hypopharynx and upper sphincter zone eventually resulting in the formation of a pulsion diverticulum [4, 5] (Schematic 2).
The lack of compliance by the cricopharyngeal muscle and the upper esophageal sphincter zone causes dysphagia (intrinsic dysphagia) which is the cardinal symptom along with choking. This lack of compliance corresponds to the typical radiological image of ‘thumb like’ impression on the cricopharyngeal transition (Photo 1). The distention of the pouch by the incoming bolus may aggravate the sensation of dysphagia (extrinsic dysphagia). Regurgitation, aspiration, ENT symptoms all are secondary manifestations of Zenker's diverticulum which is a condition occurring mainly in the elderly population (Table 1).
The therapeutic principle is based on the underlying physiopathology and consists in an extramucosal myotomy of the cricopharyngeal muscle and an upper esophageal sphincter zone and which is the essential step in the treatment of Zenker's diverticula [6, 7]. As to the diverticulum itself, it can be left alone when small (<2 cm), but for larger diverticulae either resection, diverticulectomy or diverticulopexy can be performed. This operation typically is done through a left side small cervicotomy. An alternative is the transoral endoluminal approach which consists in a split of the cricopharyngeal bar (i.e. the cricopharyngeal muscle) by using a laser or in performing an esophagodiverticulostomy using endostapler techniques. This chapter describes the open approach and shows how to perform an extramucosal myotomy of the cricopharyngeal muscle combined with a diverticulopexy fixing the diverticulum at the prevertebral cervical fascia (Schematic 3). We prefer the diverticulopexy over diverticulectomy. Diverticulopexy avoids the opening of the esophageal lumen minimizing the risk for leakage. As a result, patients are allowed to resume oral feeding at postoperative day one.
The patient is installed in supine position. A small pad is placed underneath the shoulders in order to obtain some hyperflexion of the neck. The head is slightly turned to the right. The cricoidal membrane on the trachea is identified and the skin is incised along the anterior border of the sternocleidomastoid muscle over a distance of about 6 cm. The reference point of the cricoid membrane being centered in the middle of the incision line. The length of the incision suffices to deal with almost all sizes of diverticulae (Photo 2).
After incising the platysma the dissection is continued along the anterior border of the sternocleidomastoid muscle. The omohyoid muscle is identified, mobilized and transected (Video 1).
In the same way the proximal part of the strap muscles is divided exposing now the lateral part of the left thyroid lobe. At this point a retractor is placed into the operative field retracting the sternocleidomastoid muscle laterally and the thyroid gland medially. After severing some smaller superficial vessels the dissection is continued towards the prevertebral fascia. This is done medially from the carotid vessels (Video 2).
At this point the inferior thyroid artery is identified and dissected out, clipped and divided (Video 3). The recurrent nerve lies behind, dorsally and medially, from this artery and will not be touched throughout the entire operation.
After this maneuver the diverticulum becomes already visible. But first the dissection will be carried down until the prevertebral fascia is reached and the esophagus clearly visualised (Video 4).
The diverticulum is surrounded by an envelope of connective tissue. This envelope needs to be dissected away taking great care not to open the sac of the diverticulum. Grasping the diverticulum with a Duval-type clamp facilitates this dissection. Small vessels need to be coagulated (Video 5).
It can sometimes be difficult to find the correct dissection plane between the sac and the sometimes firm connective tissue but eventually the dissection is carried down to the neck of the diverticulum (Video 6).
As the neck of the diverticulum is reached the muscular fibers become nicely visible both on the anterior and posterior side (Video 7).
The next step focuses now on performing the extramucosal myotomy which is the cardinal step of the operation. This myotomy consists of the transection of the cricopharyngeal muscle as well as of the proximal 2–3 cm of the striated cervical esophageal muscle which corresponds to the upper esophageal sphincter zone. This myotomy can be started from the basis of the diverticulum extending it downward into the cervical muscle. But sometimes it can be difficult to find a correct section plane between the muscle and the submucosa, in particular the angle between diverticulum and submucosa of the esophagus. We therefore prefer to start off from the cervical muscle zone extending the myotomy upwards until it reaches the cricopharyngeal muscle and the basis of the diverticulum. To do so two stay sutures are placed on the esophageal muscle (Video 8).
The muscle wall is incised between these stay sutures. This is a rather easy maneuver with little danger to open the mucosa (Video 9).
Now, with great care, a dissection plane is made between the muscle and submucosa using a 90° angled clamp and exerting some countertraction on the stay sutures. When dividing the muscle as the area of the cricopharyngeus muscle is reached one can observe a clear thickening of the cricopharyngeal muscle (Video 10).
The myotomy is terminated by dividing the last muscular fibers at the basis of the diverticulum, again taking great care not to damage the mucosa at this particular point (Video 11). The sectioning of the muscle is done with scissors rather than using electrocautery as the latter may cause burn lesions to the mucosa resulting eventually in a perforation due to necrosis.
The effect of the myotomy is now clearly seen with the mucosa being exposed over some 2–3 cm extending into the diverticulum. The posterior muscular wall is dissected away from the submucosa allowing to take a large biopsy of the posterior muscular wall maximizing the muscular breach and thus allowing maximal protrusion of the mucosa (Video 12). The stay sutures are removed.
The final part of the operation consists in performing a diverticulopexy. The retropharyngeal space is dissected in order to expose the prevertebral fascia to which the diverticulum will be fixed (Video 13).
As in this particular case the diverticulum is rather small, only one stitch will be needed to fix the diverticulum. Using non-absorbable 4/0 Prolene a stitch is passed firmly through the prevertebral fascia and then passed through and through both the posterior and anterior wall of the diverticulum in a U-shaped form (Video 14) and tied, completing the operation. According to the dimension of the diverticulum, several such stitches may be required. In this particular patient one stitch sufficed.
Hemostasis is performed and after placing a suction drain the wound is closed in layers. The whole intervention lasted 35 min. No nasogastric tube is used. At day 1 postoperatively a contrast study is performed and if there is no leakage the patient is allowed to resume normal oral feeding and is discharged the same day or the day after. The contrast study shows free passage of the contrast material (Photo 3).
The results of this technique have been uniformly excellent. In our own experience, dealing with 325 cases there has been no postoperative mortality (Table 2). The mean overall hospital stay decreased over time from 8.3 days down to 2.6 days over the last decade. Typically the day after the operation, a contrast study is performed; if there is no evidence of leakage, normal oral alimentation is resumed and the patient is discharged. Fistula rate was 0.1%, morbidity was 8.5% but is overall minor. Vocal cord paralysis was seen in 1%. Excellent to very good results were achieved in 94% of the patients. Eighty-five percent of the patients considered themselves as totally asymptomatic.
Fair to bad results were recorded in 3.4% and only one patient had to undergo surgery again. In this patient a primary muscular disorder was the probable cause of recurrent symptoms.
For decades the open cervical approach was the treatment of choice for Zenker's diverticulum. A minority of surgeons, mostly ENT specialists, had applied an endoluminal approach. By introducing a fixed rigid esophagoscope the common wall between the esophagus and the pouch (the so-called cricopharyngeal bar) could be divided. Whilst initially using scissors or electrocoagulation over time CO2 laser or laser beam as well as magnifying devices were introduced in order to refine the technique. However, this technique never really became popular mainly because of the fear for perforation and subsequent risk of mediastinitis. More recently the open approach as described in this chapter has been challenged by the videoendoscopic stapled diverticulo esophagectomy or endoscopic myotomy [8, 9, 10]. The latter now being performed under sedation and on an ambulatory basis [11]. The claimed advantages are no external trauma without visible scar and shorter hospital stay. It appears, however, that the videoendoscopic approach results more frequently in a need for re-intervention and in a clear and higher incidence of recurrence or insufficient control of symptoms [12]. The incidence of patients being totally asymptomatic is clearly higher when using an open approach incorporating a myotomy as compared to the videoendoscopic approach which is well reflected by two available comparative studies [13, 14]. As to the flexible endoscope approach, it appears that this technique carries a higher risk for perforation resulting in a lower clinical remission rate as compared to the surgical videoendoscopic stapled diverticulo-esophagectomy and a fortiori the open approach as described in this chapter [15]. Therefore, the open surgical approach remains the preferred method of treatment. Endoscopic techniques may be the preferred method in those occasional patients who present with contraindications for general anesthesia or open surgery.
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Summary
Historical note
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