Endoscope-assisted Transoral Approach for Parapharyngeal Space Tumor Resection.

To the Editor: The parapharyngeal space is a potential neck space between prevertebral fascia and buccopharyngeal fascia. Parapharyngeal space tumors account for 0.5% of all head and neck neoplasms, of which 80% are benign.[1] Surgical excision is the primary treatment. Surgical procedures vary depending on the tumor type, location, size, and its relationship with the neighboring nerves and vessels. Previously, an external approach was often selected, mainly through the neck, parotid gland, mandible, or orbitozygomatic structure.[2] However, following the development of endoscopic and robotic surgery, several surgeons have explored natural orifice transluminal endoscopic surgery (NOTES) to remove the parapharyngeal space tumor, which reduces complications, shortens hospital stay, and leaves no visible scar.[23] This study retrospectively reviewed 31 cases of a transoral approach in resecting parapharyngeal space tumors.

A total of 31 cases that underwent transoral approach parapharyngeal space tumor resection between January 2010 and December 2016 were collected. The inclusion criteria were parapharyngeal space tumor and/or main tumor body (exceeding 50%) located in parapharyngeal space confirmed by imaging; no main cervical vascular invasion; lateral boundary not exceeding mandibular ramus; no prevertebral muscle invasion; and no contraindications to surgery. There were 18 males and 13 females included in our study, with a median age of 37 years (range, 18–79 years) old. The median time of disease course was 5.5 months (range, 1–96 months).

All the operations were performed under general anesthesia, with a 0° or 30° rigid laryngoscopy (Karl Storz, Tuttlingen, Germany), cold plasma ablation (Arthrocare, Sunnyvale, California, USA) and suction electric coagulator (ShenTu, Tonglu, ZheJiang, China) were employed during the surgery. The mucosa was incised from pharyngeal wall or soft palate according to the tumor location. Pharyngeal constrictor was separated to expose the tumor. When the tumor was located to the medial main vessels, the vessels were isolated and protected before the tumor was separated. The cystic tumor was punctured to reduce the volume before resection. The drainage tube was removed once the drainage was less than 10 ml/day.

Pathological diagnosis was obtained: schwannomas (8 cases), salivary pleomorphic adenomas (5 cases), angiomas (5 cases), branchial cysts (3 cases), Castleman disease (2 cases), and 1 case for each of the followings: lymphoepithelial cysts, thyroid cancer lymphatic metastasis, phosphate urinary mesenchymal tissue tumor, basal cell adenoma, myoepithelial carcinoma, fibroma, adenoid cystic carcinoma, and lipoma. Twenty-eight tumors laying medial to the internal carotid artery (ICA), 2 tumors laying lateral to the ICA, and 1 tumor surrounding the ICA over 180°. The average tumor diameter was 4.6 ± 2.1 cm (2–12 cm). Magnetic resonance imaging results of typical patients are shown in Figure 1.

Figure 1

Magnetic resonance imaging results of typical patients. Axial (a) and coronal (b) views of angioma, tumor lay medial to ICA (red arrow); axial (c) and coronal (d) views of phosphate urinary mesenchymal tissue tumor, ICA (white arrow) was pushed by the tumor; axial (e) and coronal (f) views of pleomorphic adenomas, tumor lay lateral to ICA (white arrow); axial (g) and coronal (h) views of schwannoma; axial (i) and coronal (j) views of lymphoepithelial cysts; axial (k) and coronal (l) views of schwannoma, tumor lay lateral to ICA (red arrow) and medial to external carotid artery (white arrow). ICA: Internal carotid artery.

Thirty tumors were transorally resected, and one patient received a combined approach with transcervical access. Twenty-seven tumors were removed en bloc, while 4 cases were resected piecemeal. No large cervical vascular injury occurred during the surgery. The wound surface was directly sutured in 15 cases and drained in 16 cases. The median operation time was 2.5 h (1–8 h), and the median bleeding amount was 50 ml (10–1800 ml). The mean postoperative hospital stay was 7.0 ± 2.7 days (4–14 days). No patients underwent tracheotomy. Three patients at a high risk for airway failure returned to Intensive Care Unit after surgery and were extubated after 24–48 h.

Patients were followed up for 28.5 months (3–84 months). No recurrence was observed at the last follow-up. Complications included effusion in 1 case (self-healing), transient hoarseness in 2 cases, soft palate necrosis in 1 case (scar healing), and secretory otitis media in 1 case (recover after treatment). No patients suffered from permanent nasopharyngeal reflux or posterior cranial neural paralysis.

There are about 70 pathological types found in the parapharyngeal space. The most common neoplasms occurring in this space are of salivary and neurogenic origin, accounting for 45% and 41%, respectively. The remaining 12% are other types of primary tumor, and 2% arise from lymph node metastasis.[1]

In this study, two lesions were located lateral to ICA, which were realized as schwannoma without vessel invasion on the basis of imaging studies. The ICA was separated and protected first, then, the tumor was completely resected. Three low-grade malignant tumors were proved 1 week after the operation, and the tumor was removed en bloc without recurrence (follow up, 16–84 months). The capsule of three cysts ruptured during the surgery; however, the cyst was completely excised under endoscopic guidance.

In conclusion, all the important structures can be identified through the endoscope.[4] Parapharyngeal space tumors can be completely resected by an endoscopic-assisted transoral approach, even in cases with tumors lying lateral to the ICA. A second open surgery is not necessary for those low-grade malignant en bloc removed tumors. This endoscopy-assisted approach is generally safe and the advantages include no visual scar and shorter hospital stay.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.