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Transoral Robotic Surgery (TORS)

 return to:Cancer Management Principles

or: Oropharyngeal Cancer Management

GENERAL CONSIDERATIONS/INDICATIONS

 Originally cleared by the FDA  in December 2009 for use in surgical procedures to treat benign tumors and select malignant tumors of the mouth, throat and larynx in adults.

TLM + TORS = TOS

TLM = transoral laser microsurgery; can access some tumors that TORS cannot; tumor not removed en bloc

TOS = transoral surgery

   Benefits of TORS

  •   Avoidance of disfiguring mandibulotomy 
  •   Minimization or elimination of need for chemoradiation therapy
  •   Avoidance of tracheostomy
  •   Quicker return to normal speech and swallowing  
  •   Significantly less pain
  •   Decreased blood loss
  •   Shorter recovery time and hospital stay

   Risks of TORS

  • Bleeding - can be severe and life-threatening
    • Post op day 10 is the most common time
      • media injury > aneurysm > rupture
  • Dysphagia - requiring initial feeding tube supplementation
  • Dysgeusia
  • Fistula - highest risk when performed in conjunction with neck dissection
  • Nasopharyngeal reflux
  • Velopharyngeal insufficiency

 

Evaluation

  • It's essential to confirm by both endoscopy and imaging that a patient's anatomy (and the tumor itself) are amenable to the robotic approach. This is most critical for approaches to the supraglottic larynx
  • Rule of T's
    • Tongue (relative macroglossa)
    • Tumor
    • Trismus
    • Transverse dimension (mandible)
    • Tori
    • Tilt (head extension)
  • Preoperative CT scan - identify aberrant vascular anatomy, especially medialized carotid

A. The main anatomical areas for which TORS may be applied (those reported in the literature): 

  • Oropharynx - tonsil, base of tongue, palate, pharyngeal wall
  • Skull base
  • Parapharyngeal space
  • Larynx - usually requires TLM
  • Hypopharynx - usually requires TLM
  • Supraglottis

 

Pertinent Anatomy

 

TONSIL & BOT
  • Lingual nerve runs between the medial pterygoid and the ramus
  • Lingual artery
    • arises from ECA at level of hyoid - intimately related to greater horn of hyoid - link these structures in your mind
    • just deep to the superior constrictor along the ramus
    • divided into 3 parts by hyoglossus:
      • oblique loop - arises just above greater horn of hyoid, posterior to hyoglossus belly.  Crossed superiorly & laterally by XII
        • Loop permits free mvmt of the hyoid bone
      • horizontal - deep to hyoglossus, runs forward along superior border of hyoid, resting on middle constrictor; stylohyoid ligament medially;
        • gives off dorsal lingual branches to BOT, palatoglossus, tonsil, soft palate
      • vertical “deep lingual" - ascends along anterior border hyoglossus between genioglossus medially & inferior longitudinal laterally
        • > then forward along the ventral surface of tongue (just deep to mucosa) lateral to each frenulum; accompanied by lingual n. 
        • sublingual a branches off just anterior to hyoglossus - course between genioglossus & mylohyoid —> sublingual gland, FOM
    • the only major structure that passes medial to hyoglossus; XII and lingual n run lateral to the muscle and the artery
    • Dorsal lingual can be problematic in BOT resections - easy to find so clip it if you do
  • Styloglossus & Stylopharyngeus 
    • deep to parapharyngeal fat
    • diverge from superior to inferior (similar in arrangement to palatoglossus/-pharyngeus)
    • below the divergence there is just a 2mm thick swath of superior constrictor in tonsil fossa bed
    • find IX between these muscles
    • Styloglossus - anterior, more horizontal trajectory 
      • ID lingual vessels under the belly of SG
    • Stylopharyngeus - posterior more vertical trajectory, more fan-shaped.  
      • Passes between superior & middle constrictors with stylohyoid ligament
      • Crosses directly over IX and partially obscures it (this is the nerve's only motor contribution)
  • Prestyloid space = area between medial pterygoid & superior constrictor - contains tonsillar vessels
  • IX glossopharyngeal nerve
    • main trunk of IX can be identified at intersection of posterior pillar and BOT
    • should be able to retain main trunk but smaller branches will be sacrified
    • more you leave > better swallow function (better sensory)
  • XII hypoglossal nerve
    • descends from skull base behind the ICA, IX and X
    • then passes btw ICA and IJV, crosses in front of X, over ICA/ECA & lingual a
    • runs along superior border of hyoid > deep to digastric and mylohyoid
  • BOT musculature resected in radical tonsillectomy is primarily intrinsic tongue musclulature + hyoglossus, styloglossus
    • dorsal lingual branch of lingual a. is the single major artery encountered

Tonsil vs BOT

  • easier to expose
  • more complex anatomy
  • more blood vessels
  • higher risk VPI, nasopharyngeal reflux

 

Contraindications

  •  The standard contraindications for head and neck surgery, both conventional and minimally invasive, should be practiced when selecting patients for TORS  including:
    1. The presence of medical conditions contraindicating general anesthesia or transoral surgical approaches
    2. Inability to adequately visualize anatomy to perform the diagnostic or therapeutic surgical approach transorally
    3. Unresectability of involved neck nodes  
  • Specific contraindications for TORS procedures regardless of region or procedure:
    1.  Mandibular invasion
    2.  Tongue base involvement requiring resection of greater than 50% of the tongue base
    3.  Pharyngeal wall involvement requiring resection of more than 50% of the posterior pharyngeal wall
    4.  Radiologic confirmation of carotid artery involvement
    5.  Fixation of tumor to the prevertebral fascia
    6.  Medialized carotid artery lying adjacent to tonsil (contraindication for radical tonsillectomy, not tongue base resection)


PREOPERATIVE PREPARATIONS
   OR equipment and robotic supplies

  • Warming blanket (Bair Hugger)
  • Cautery unit with Bovie pedal and bipolar pedal - one pedal next to assistant for suction cautery
  • Two Bovie pads
  • Reusable bipolar cord
  • Surgical high-magnification camera head (45 FOV)
  • Surgical wide-angle camera head (60 FOV)
  • Ikegami high-definition 3D imaging system (da Vinci® S™ only)
  • 30 degree Surgical endoscope
  • 0 degree Surgical endoscope
  • Surgical headlight
  • Three chairs that have a foot pedal for adjusting up and down - two at bedside (for the nurse and the bedside surgical assistant) and one at surgeon console
  • Three rectangular OR instrument carts and one small square OR instrument cart


A. Operating Room Configuration

  1. Turn bed 180º from anesthesia
  2. Robot patient cart to right of patient - bring in after turn bed
  3. Assistant works SEATED at the patient’s head
  4. Scrub nurse stands to left of patient

B.Patient Positioning & Preparation

  1. Supine position, patient’s head positioned towards the feet of the OR table (patient backwards on OR table, as with otologic cases)
  2. Spin OR table 180° with feet towards anesthesia
  3. Nasotracheal intubation vs oral intubation (surgeon preference)
    1. if nasotracheal - intubate with nasal RAE in nare contralateral to tumor to facilitate ETT as far from surgical site as possible
    2. if orotracheal - oral RAE is preferred
  4. Standard patient protective measures are used if laser instrumentation is applied
  5. Surgical site exposure with mouth gag (Crowe-Davis vs Davis Meyer)
  6. 2-0 silk stay suture through midline of oral tongue - to allow retraction of tongue to contralateral side
    1.  Additional stay sutures intraorally as indicated
  7. Confirm that the laryngopharynx can be visualized sufficiently before procedure start

C.Mouth Gag Placement

  1. Oropharynx: Position the Crow-Davis or Davis Meyer mouth gag to fully visualize the target anatomy
  2. Larynx: Position the Feyh-Kastenbauer (FK) retractor  for an initial view that includes the epiglottis and vallecular mucosa
  3. Oral Cavity: Crow-Davis mouth gag, Jennings mouth gag, Molt side biting retractor are useful for exposure of more anterior targets. 

D. Docking

  1. Lower OR table all the way down 
  2. Position arms of patient cart as high as possible to clear patient’s chest/head
  3. Align patient cart, camera arm and mouth gag midline in a straight line
  4. Identify “sweet spot” on arms to allow for correct setup. The camera arm setup joint should be placed towards the right to avoid collisions with the left arm
  5. Patient cart to come in at ~ 30° angle from the patient’s right
  6. Point instrument tips toward center of target anatomy using set-up joint or port-clutch maneuvers
  7. Maximize spacing between all robotic arms
  8. **CAUTION: Once the robotic patient side cart is moved into position and the instrument arms positioned intraorally, the OR table should no longer be moved.

E. Camera & Instrument Arm Setup

  1. Camera 12 mm: Camera arm inserted in a vertical line over the patient’s chest midline through mouth gag with cannula tip intraorally.  The camera arm should first be positioned at its highest point.  The camera is then advanced to its furthest position and the entire camera arm then placed intraorally paralleling the tongue blade until it is just shy of the target. 
  2. Instrument Arms 5 mm: Position cannulas remote center (thick black line) well outside the mouth and the cannula tip roughly at the level of the mouth gag frame. Adjust the insertion angle so that the instruments can be seen just past the tip of the endoscope.
    1. Cautery arm on ipsilateral side of tumor, grasper on contralateral side

OPERATIVE PROCEDURE (EXAMPLE)--RADICAL TONSILLECTOMY

F. Radical Tonsillectomy

1. After exposure of tonsillar fossa and base of tongue, an incision is made in the mucosa just posterior the retromolar trigone.  This incision is done either with a CO2 laser or monopolar cautery and is carried through the pterygomandibular raphe (where the superior constrictor meets the buccinator) until the medial pterygoid muscle  and parapharyngeal fat pad are identified. These landmarks confirm that the dissection is now outside of the constrictors.  Dissection is continued posteriorly hugging the superior constrictor muscle to avoid injury to structures within the parapharyngeal space.  The styloglossus and stylopharyngeus muscles will be encountered.  These muscles should be skeletonized adjacent to the superior constrictor and divided as medially as possible to avoid injury to the great vessels. The cautery blade can be used to bluntly elevate the constrictor off of the prevertebral fascia.

2. An incision is then created along the posterior pharyngeal wall well away from the posterior limits of the tumor.  This incision is best made early in the resection as it is more difficult to visualize this area once the tumor and lateral pharyngeal tissues have been mobilized.
3.  The soft palate cut can then be incised to connect the previous two dissection planes and begin lifting the specimen up resecting as much posterior pillar and posterior constrictor muscle as necessary to obtain clear margins

4.  The tongue base incision is then created taking an adequate cuff of tongue base to assure negative margins.  If dissection requires deep resection of the tongue base be aware of the lingual artery and clip it with several endoscopic hemoclips to prevent life threatening bleeding in the post operative setting. 

5.  The specimen can now be removed with care to maintain orientation for pathologic analysis of margins.

6.  Hemostasis is confirmed and floseal placed into wound at the discretion of the surgeon

7.  Direct visualization of feeding tube placement prior to removal of mouth gag/retractor

G. Tongue base Resection

 

SUGGESTED READING
Chi JJ, Mandel JE, Weinstein GS, O'Malley BW Jr. Anesthetic Considerations for transoral robotic surgery Anesthesiol Clin;2010 Sep;28(3):411-22. Epub 2010 Aug 11

O'malley BW Jr, Weinstein GS, Snyder W, Hockstein NG. Transoral robotic surgery (TORS) for tongue base neoplasms. Laryngoscope 2006. Aug; 116 (8): 1465-72.

Weinstein GS, O'Malley BW Jr, Snyder W, Sherman E, Quon H. Transoral robotic tonsillectomy. Arch Otolaryngol Head Neck Surg. 2007 Dec;133(12):1220-6.

Genden EM, Desai S, Sung CK.  Transoral robotic  surgery for the management of head and neck cancer: a preliminary experience. Head Neck. 2009 Mar;31(3):283-9.

Murray S. Nursing care for patients undergoing transoral robotic surgery. ORL Head Neck Nurs. 2009 Winter;27(1):8-12.

Lim CM, Mehta V, Chai R, Pinheiro CN, Rath T, Snyderman C, Duvvuri U. Transoral anatomy of the tonsillar fossa and lateral pharyngeal wall: Anatomic dissection with radiographic and clinical correlation.  Laryngoscope. 2013 Dec;123(12):3021-5.

Wang C, Kundaria S, Fernandez-Miranda J, Duvvuri U. A description of arterial variants in the transoral approach to the parapharyngeal space.  Clin Anat. 2014 Feb 7.

Moore EJ, Janus J, Kasperbauer J.  Transoral robotic surgery of the oropharynx: Clinical and anatomic considerations. Clin Anat. 2012 Jan;25(1):135-41.