**5. Surgical procedures**

#### **5.1 Setting**

TOVS is performed under general anesthesia by orotracheal intubation using a small diameter (6–7 mm) reinforced endotracheal tube. When the resection area includes the epiglottis and tongue base, nasotracheal intubation is recommended.

To expose the surgical fields, a FKWO retractor with various blades, including large blade, laryngeal blade, and tongue base blades, is the most useful for laryngopharyngeal lesions. Attaching pre-made mouthpieces to prevent tooth injury is also recommended. Although surgical field exposure is the most principal and important step to complete transoral surgery successfully, it is one of the most difficult steps that requires extensive experience and many learning curves.

Basic techniques for obtaining good surgical field exposure are as follows. For piriform sinus lesions, the laryngeal blade or tongue base blade is inserted into the glottis, vallecula of the epiglottis, or anterior end of the piriform sinus lateral of the pharyngoepiglottic fold and the aryepiglottic fold (**Figure 2a, b**). For posterior wall

**Figure 2.**

*Technique of surgical field exposure. a. Right piriform sinus lesion, b. right piriform sinus lesion, c. posterior wall lesion, d. Postcricoid lesion, e. esophageal inlet lesion, f. Epiglottic lesion.*

lesions, the laryngeal blade is inserted into the glottis or postcricoid area (**Figure 2c**). In some of these cases, it is effective and helpful to obtain good surgical fields that the blade is inserted behind the endotracheal tube, and the tube is pushed forward (**Figure 2b, c**). For postcricoid and esophageal inlet lesions, the laryngeal blade is inserted into the glottis or postcricoid area behind the endotracheal tube, and the tube is pushed forward (**Figure 2d, e**). For epiglottic and tongue-based lesions, the tongue base blade is inserted into the tongue base (**Figure 2f**). Poor ventilation by kinking of the tracheal tube can occur due to compression by the blade, and a careful procedure is needed.

These instruments can expose most lesions; however, some patients have poor laryngopharyngeal exposure. For patents who have poor laryngopharyngeal exposure by conventional blades, novel prototypes of curved blades are currently under development (**Figure 3**). These new blades are effective to expose the distal hypopharynx to the esophageal inlet [5].

### **5.2 Evaluation**

TOVS is performed by two head and neck surgeons. The operator manipulates instruments bimanually, and the assistant holds the videoscope to maintain an appropriate view of the surgical fields (**Figure 4a**). Occasionally, the assistant holds another pair of forceps or a suction device to support operator (**Figure 4**).

To evaluate the extent of the lesions and mark the resection area of the laryngopharynx, Endoeye flex with the function of image-enhanced endoscopy (NBI) is an ideal tool for this surgery. After meticulous washing of the laryngopharynx to remove blood and saliva with physiological saline, the lesion extent is evaluated by endoscopic vision with normal light and NBI (**Figure 4b, c**). Subsequently, iodine staining is performed to show the mucosal extent of the lesions. After 1% iodine solution is sprayed around the lesions and rinsed with physiological saline, superficial lesions can be clearly demarcated as iodineunstained areas (**Figure 4d**). This procedure is particularly effective in identifying the boundary of lesions in hypopharyngeal cancer and oropharyngeal cancer, except that of tongue base lesions.

Palpation using forceps is also an important procedure to evaluate tumor size and deep infiltration and determine whether the lesions can be resected. In the case of lesion immovability and/or finding anatomical contraindications during the evaluation process, discontinuation of TOVS should be considered.

#### **Figure 3.**

*Novel blades for FKWO retractor. A: Prototype of curved blades, b: Representative case (Postcricoid lesion), conventional blade (left), curved blade (right).*

Thereafter, the incision line of the mucosa around the lesions is marked with a safety margin of 5–10 mm using needle-type electrocautery (**Figure 4e**). Due to cases of multiple sporadic mucosal lesions, evaluation of the entire laryngopharynx is recommended.

#### **5.3 Resection**

A soft suction tube is placed transnasally to prevent blurry vision by smoke and blood. After circumferential mucosal incision, the operator manipulates the grasping forceps to grasp and retract the edge of the lesion. Appropriate counter traction is applied to determine the appropriate incision layer and enables resection of appropriate tissue by electrocautery. In many cases, resection from the periphery to the inside enables en block resection (**Figure 4f–j**). It is important to confirm deep infiltration by palpation during the procedure. Representative cases are presented in Section 9.

Although hemostasis can be performed with a suction coagulator in most cases, multiple vessel clips should be used when thick blood vessels can be confirmed (**Figure 4k**). Bleeding from the posterior wall, the branch of the superior laryngeal artery running from the upper outside of the thyroid cartilage, or the branch of the lingual artery, is occasionally difficult to control.

Frozen section pathological analysis with the stumps of surgical margins in at least four horizontal directions and a deep margin is performed. In addition, the extracted specimen is stained with iodine to confirm the sufficiency of safety margin. Additional resection is performed based on these results when necessary.

#### **5.4 End of surgery**

In some cases, fibrin glue is sprayed to the wound to prevent bleeding (**Figure 4l**). However, it is not necessary due to the possibility of it becoming a foreign body in the airways. A nasogastric tube is inserted in cases with a high possibility of postoperative dysphagia (**Figure 4**).

#### **Figure 4.**

*Step-by-step procedure (Hypopharyngeal cancer, Rt. piriform sinus lesion). a. outside view of TOVS, b. observation with normal light, c. observation with NBI, d. observation after iodine staining, e. marking of the mucosal incision line, f. resection from the oral side, g. resection of the muscular layer, h. resection of the inner border of the thyroid cartilage, i. resection of the caudal end, j. view after resection, k. hemostasis using vessel clip, l. view after spraying of fibrin glue.*

Local steroid injection (triamcinolone acetonide) is also performed to reduce the degree of postoperative scar contracture in selected non-irradiated cases. In deeply invasive tumors and previously irradiated patients, this procedure may cause wound healing complications; hence, local steroid injection should be considered in only new cases with extensive excision of the pyriform sinus, postcricoid, and/or esophageal inlet lesions [9].

TOVS can be completed without tracheostomy if no bleeding and no severe airway stenosis due to laryngopharyngeal edema is confirmed. The endotracheal tube is basically extubated immediately after surgery. In cases with suspected airway stenosis risk, extubation should be performed under preparation for immediate reintubation using a tube exchanger. Patients who have a high risk of bleeding after surgery or severe laryngopharyngeal swelling due to long surgery or neck dissection should be kept intubated or should undergo tracheostomy without hesitation.

## **6. Management of lymph node metastasis**

For patients with node-positive disease, ND is performed after TOVS on the same day. Some patients may undergo ND separately within 1–2 weeks of TOVS.

The veins around the laryngopharynx should be preserved whenever possible to reduce postoperative laryngeal edema due to temporal insufficiency of blood flow. In N2c cases treated with bilateral NDs, severe edema of the entire laryngopharynx can occur. Therefore, careful attention should be paid to postoperative airway management and prophylactic tracheostomy should be considered.

Perforation between the wound of the TOVS and the neck can occur during ND. In such cases, postoperative infections, particularly around the carotid artery or retropharyngeal space, might be a fatal complication. Therefore, closure using a muscular flap should be performed and careful and intensive postoperative management to prevent subcutaneous emphysema and infections are necessary.
