The present case highlights two important clinical issues in KJD. One is that diverticulectomy is achievable via a partial cricopharyngeal myotomy, and the other is that a TGF may reduce the risk of postoperative complications.
Suture or staple line leakage following diverticulectomy reportedly occurs in 1.7% to 12.7% of cases [7], and this complication poses a risk of cervical infection and stenosis [5]. Although surgery for KJD is rare, one case report described the occurrence of staple line leakage that was treated by enforced fasting [4]. There is currently no information on the prevention of leakage after diverticulectomy. However, we considered that coating and reinforcing the suture line using a TGF, which is available in the same surgical field, is a minimally invasive and promising method for preventing suture or staple line leakage. Covering the staple line using the sternothyroid muscle is a simple and useful procedure. Swallowing dysfunction can reportedly be caused by defective relaxation of scarred sternohyoid and sternothyroid muscles [8]. Because most chief complaints in patients with KJD are related to swallowing dysfunction, a TGF is an option for this procedure. The use of a TGF for glottic reconstruction after vertical laryngectomy was initially reported in 1990 by Kojima et al. [9]. Since then, the effectiveness of a TGF has been demonstrated in larynx-preserving pharyngectomy and supracricoid partial laryngectomy after radiochemotherapy [6, 10]. Furthermore, Ogawa et al. [6] showed that a TGF with a sufficient blood supply prevents cervical infection and dehiscence. We harvested a TGF from the superior aspect of the designated thyroid lobe. The TGF had an adequate blood supply via the superior thyroid artery, which is the first branch of the external carotid artery, and was smoothly rotated and moved to the staple line area. The staple line was not buried because of the proximity of the RLN course to the diverticulum stump. Therefore, we reinforced the staple line by suturing to completely cover it on the cut surface of the TGF. The TGF is also less likely to shrink than other flaps because of its abundant blood supply [9]. In the event of cervical infection, the area of the diverticulectomy is adequately filled, and this blood supply ensures high local drug concentrations, thereby preventing further complications. However, because a previous study showed the potential for postoperative thyroid enlargement, respiratory disturbances need to be considered [11]. No complications were observed in the present case, and respiratory disturbances were unremarkable. Furthermore, there was no thyroid swelling caused by congestion because the superior thyroid vein is located lateral to the artery. If the parathyroid glands are removed at the same time as formation of the TGF, the diverticulum resection area is filled with the TGF containing the parathyroid glands. For the safety of the patient, the serum calcium level should be measured several times postoperatively to confirm that there are no abnormalities.
Whether partial cricopharyngeal myotomy is adequate for KJ diverticulectomy remains controversial. We consider that myotomy provides a sufficient surgical field in which it is safe to perform diverticulectomy after identification of the RLN. Appropriate diverticulectomy at the base may prevent recurrence of the diverticulum. The gold standard for the surgical treatment of a ZD is complete cricopharyngeal myotomy using an external approach. However, because of the risk of postoperative cricopharyngeal muscle dysfunction, we consider it preferable to perform an incomplete (approximately half) cricopharyngeal myotomy that exposes the base of the diverticulum. Transcervical diverticulectomy should be performed using an IONM system because of the high risk of injury to the RLN, which enters the neck at the base of the diverticulum [12]. Because the RLN is located behind the cricopharyngeal muscle, IONM systems are also useful in cricopharyngeal myotomy at the cranial side of the diverticulum. Early localization and identification of the RLN was possible in the present case, and the diverticulum was easily dissected from the surrounding tissue in a short period. It may be difficult to define the RLN when the KJD is associated with chronic inflammatory changes [13]. The diverticulum is often resected at its base using a linear stapler. Although a linear stapler is generally used longitudinally, we transected the diverticulum transversally under the guidance of upper intestinal endoscopy [12]. A sufficient surgical field after myotomy facilitates reliable transverse dissection to the cranial side of the diverticulum.
Our method raises concerns about thyroid function and disease, such as chronic thyroiditis and Graves’ disease; therefore, preoperative morphological and functional assessments of the thyroid gland are mandatory. Even in euthyroid patients, preoperative cervical ultrasonography should be performed to confirm the absence of thyroid gland abnormalities. Testing of perioperative thyroid function is also important. Anatomical variations in the location of the RLN have been reported for different diverticula [12, 14, 15]. The anatomical position of the diverticulum may affect the methods required to diagnose the cause of oropharyngeal dysphagia [14]. Barium esophagography often establishes the diagnosis of a pharyngoesophageal diverticulum. A KJD is detected on the lateral wall of the pharyngoesophageal junction and below the cricopharyngeal muscle (cricopharyngeal bar) on the anteroposterior view [16]. Because of its proximity to the thyroid gland, a KJD may be misdiagnosed as a thyroid lesion or nodule. On computed tomography, it is important to distinguish between a cystic lesion and an air-containing cystic lesion originating from the esophagus anterolaterally [17, 18].
