TORS
Since 2018, prestyloid surgery at our center has been based on a medial approach with TORS – either alone or in combination with a transcervical incision when necessary – using the da Vinci Xi (Intuitive Surgical, Inc, Sunnyvale, CA) docked at the patient’s left side. The oropharyngeal cavity is accessed with the Feyh-Kastenbauer retractor modified by Wenstein-O’Malley (Olympus Corp). Surgery is performed with a slightly tilted head-up position. A single dose of dexamethasone 4-8 mg is administered to avoid postoperative airway edema. Prophylactic tracheostomy is not a usual procedure. Patients with postoperative edema or those in whom there are doubts about airway safety remain intubated for 24 hours; if the situation does not improve, a temporary tracheostomy is considered.
TORS starts with 0-30-degree scope and the Endowrist TM instruments (Intuitive Surgical, Inc).6 The initial incision is made in the pterygomandibular raphe; once the palatoglossus and constrictor muscles are dissected, the prestyloid PPS is exposed by blunt dissection.11 When there is lateral extension, the lateral pterygoideus muscle is cut to expand the axial axis of the surgical corridor. When a lateral extension cannot be controlled with TORS alone, it is combined with a transcervical incision (Figures 1-2) to dissect the lateral edge of the tumor.
We use the optical BrainLab as an intraoperative image-guided navigation system with CT and/or MRI images. The pterygoid plates, styloid process, and first cervical vertebrae are used as a guiding reference. The head fixation is done by fixing the array with a clamp to the head holder or to the mouthgag-fixation-bed block without using the head holder (Figure 3). The registration process is based on a point correlation technique. Navigation is performed using the optical tracking system with the soft-touch pointer.
We use a second navigation system based on ultrasound guidance using a 20 MHz disposable doppler probe (Mizuho Medical Co. Ltd.) to identify vascular structures.