see (for incision and f/u): Case Example Lip Split for Mandibulectomy

see also: Segmental and Rim Mandibulectomy

Note: last updated before 2013

GENERAL CONSIDERATIONS

1. Indications
   1. This approach allows access to the oral cavity and pharynx for excision of mucosal and submucosal tumors.
   2. In conjunction with a transcervical extension, this approach may also be used to gain access to the parapharyngeal space for excision of tumors in this area.
   3. A midline mandibulotomy and median glossotomy may also be used to gain access to the cervical spine.
   4. For patients undergoing anterior segmental resection, the mandibulotomy is incorporated into the segmental resection. This technique affords excellent exposure in cases where reconstruction will be performed with an innervated osteocutaneous free flap and the inset requires "layering in" of the flap components.
2. Contraindications
   1. Patients who strongly object to a lip-split incision should be considered for a lingual releasing approach (see Lingual release protocol).
   2. A small atrophic mandible is a relative contraindication to this technique, and improved healing may be obtained with a lingual release.
   3. Poor dental hygiene adjacent to the mandibulotomy may predispose to osteotomy sepsis.
   4. If there is a question of tumor invasion of the more distal mandible, an anterior mandibulotomy should not be created until after the extent of mandibular resection required to remove the tumor is determined.
3. Pertinent Anatomy
   1. The depressor labii inferioris, depressor anguli oris, and mentalis muscles are to some degree disrupted if a circummental lip-split incision is made. For this reason, the midline Z-type incision is preferred.
   2. The mental foramen lies inferior to the first premolar, which corresponds to a position inferior to the oral commissure.
   3. The canine is an excellent tooth for use as a dental abutment for tissue-borne dental prostheses. The mandibulotomy should not compromise this tooth or its root.
   4. With care, there is sufficient space between the incisor tooth roots to perform a mandibulotomy without the need to extract a healthy tooth.
   5. The digastric and genioglossus muscles attach in the midline.  The mandibulotomy (if performed in a paramedian position) may be placed lateral to these muscles and medial to the mental foramen.

PREOPERATIVE PREPARATION

1. Evaluation
   1. Careful consideration is given to the question of whether mandibulotomy for access or segmental mandibulectomy for excision of the tumor is required. If the tumor excision will require segmental resection, the "mandibulotomy" bone cut will serve as the anterior bone cut of the segmental resection.
   2. A CT scan and panoramic radiograph of the mandible should be evaluated for tumor invasion, dental root status, and potential mandibular pathology such as a cyst or quiescent periapical disease.
   3. Dental prosthetic service consultation should be obtained for a full dental evaluation prior to planning the intended site of the mandibulotomy. This will allow for the incorporation of any recommended dental extractions into the operative plan.
2. Potential Complications
   1. Malunion or nonunion of the mandibulotomy site potentially requiring removal of hardware and refixation
   2. Malocclusion or a notable change in occlusion in the dentate patient
   3. Injury to the mental nerve
   4. This approach will require a lip-split procedure, and the patient should be aware of the cosmetic and potential functional consequences of that approach.

NURSING CONSIDERATIONS

1. Room Setup
   1. See Basic Soft Tissue Room Setup
   2. Back table x 2
2. Instrumentation and Equipment
   1. Standard
      1. Major Instrument Tray 1, Otolaryngology
      2. Major Instrument Tray 2, Otolaryngology
      3. Bipolar Forceps Trays
      4. Hall Micro Sagittal Saw Tray (Pneumatic)
      5. Nerve stimulator control unit and instrument
   2. Special
      1. KLS Oto Trauma Implant - Instrument Tray or
      2. KLS Free Flap Implant - Instrument Tray or
      3. KLS Locking Reconstruction Threadlock Instrument Tray or
      4. KLS mandibulectomy or
      5. KLS maxillectomy or
      6. Bien Otologic Electric Drill Tray
      7. Tracheotomy Tray (available only)
      8. Extraction Tray
      9. Varidyne vacuum suction controller
      10. Dentistry Basic Instrument Tray
      11. 20 cc syringe with 18-gauge blunt needle for irrigation
      12. Cummings retractor: large and medium
      13. Dingmann bone clamps
      14. McKesson mouth prop, adult, large
      15. Molt mouth gag, adult
      16. Minnesota retractor
      17. Shearer retractor
      18. Corpak feeding tube
      19. Bone wax
3. Medications (specific to nursing)
   1. 1% lidocaine with 1:100,000 epinephrine
   2. Antibiotic ointment
4. Prep and Drape
   1. Standard prep, 10% providone iodine
   2. Drape
      1. Head drape
      2. Towels to square off around incision line
      3. Split sheet
5. Drains and Dressing
   1. Varidyne vacuum suction drains: 7 mm to 10 mm
6. Special Considerations
   1. If mental nerve divided, order Microsurgery Instrument Tray, Otolaryngology to reanastomose with nylon 9-0.
   2. Tracheotomy may be performed either initially or as part of the procedure.
   3. Dental procedure may be necessary.

ANESTHESIA CONSIDERATIONS

1. General
   1. The table turned with the head 180° from the anesthesiologist.
2. Specific
   1. Avoid venous access via the neck.
   2. Avoid paralysis until after identification of the mandibular branch of the facial nerve if that is required.
   3. Once the facial nerve is identified and protected, full relaxation of the patient through muscular paralysis will facilitate exposure of the oral cavity and pharynx.
   4. For large oral and pharyngeal tumors that preclude a safe oral intubation, the case may be started with a local tracheotomy. Discuss this option with the anesthesiologist prior to bringing the patient into the room.

OPERATIVE PROCEDURE

1. If dental extractions are planned, these should be done before mandibulotomy or mandibulectomy.
2. Lip-split access to the anterior mandible
   1. The mucosal incision in the floor of mouth and through the gingiva should not be directly over the mandibulotomy.
   2. A lip-split with a midline-Z incorporating the mental crease is used. The skin incision descends vertically from the vermilion to a point about 0.8 to 1 cm above the mental crease. At this point, it is angled to join the mental crease about 0.8 to 1 cm off the midline. The incision then travels horizontally within the crease to a symmetric point on the contralateral side. From this point, it is angled back to the midline, opposite but symmetric with the angled incision above the mental crease. A step at the vermilion border allows the incision through the red lip, gingivolabial sulcus, and floor of mouth to be in a paramedian position on the side opposite the paramedian mandibulotomy. This is preferred to a circummental incision and places the incision through the mucosa away from the intended mandibulotomy site.
   3. The lip-split incision is carried laterally to form the neck incision.
3. The lip-split incision is carried down to the muscular fascia. Then, the deeper aspect of the incision is made in the midline to avoid damage to the mentalis muscle.
4. The intended mandibulotomy is marked on the mandible. The mandibulotomy is vertical between the tooth roots (usually between the medial and lateral incisors) if present. The cut then angles gently in a posterior direction to a point just lateral to the digastric muscle. For mandibular stabilization, two 2 mm mandibular plates are placed. One is placed along the inferior border of the mandible, and the other is placed just above this. A minimum of three screws on each side should be used.
5. The plates are contoured and placed preliminarily prior to creating the mandibulotomy. The mandible may be smoothed slightly with a drill to allow for perfect adaptation of the plates.
6. Once the plates have been contoured, they are removed and the bone cut is made.
7. In the dentate patient in which the bone cut is made between tooth roots, great care must be taken with the bone cut to prevent injury to the cuff of bone left around the root.
8. When fixating the bone after tumor removal, be aware that if the plates have been contoured prior to the mandibulectomy, a gap the width of the saw cut will be present between the cut ends. Closing this gap in the dentate patient may introduce a malocclusion.
9. In the edentulous patient, it is not necessary to contour the plates prior to the mandibulotomy. The small change in mandibular position introduced by the bone cut will not be noticeable to the edentulous patient as it is to the dentate patient.
10. Following the oncologic procedure, the previously contoured plates in the dentate patient are reapplied. In the edentulous patient, plates are adapted and fixated.
11. The intraoral mucosa is closed carefully. Tearing the thin mucosal lining present on the medial aspect of the mandible may create a route for saliva to contaminate the mandibulotomy. Occasionally, gentle elevation of the densely adherent musosa of the mandible off the mandible for about 1 cm allows a less traumatic closure in this area.

POSTOPERATIVE CARE

1. Patients remain on perioperative antibiotics for 48 hours.
2. Oral rinses are done QID with normal saline: hydrogen peroxide in a 1:1 ratio beginning on postoperative day 1.
3. Suction drains remain until the drainage is less than 30 ml per 24 hours.
4. Nonirradiated patients may begin PO intake on postoperative day 7.
5. The patient should follow a soft diet for six weeks.

SUGGESTED READING

Christopoulos E, Carrau R, Segas J, et al. Transmandibular approaches to the oral cavity and oropharynx. Arch Otolaryngol Head Neck Surg. 1992;118:1164-1167.

Dubner S, Spiro RH. Median mandibulotomy: a critical assessment. Head Neck. 1991;13:389-393.

Shah JP, Kumaraswamy SV, Kulkarni J. Comparative evaluation of fixation methods after mandibulotomy for oropharyngeal tumors. Am J Surg. 1993;166:431-434.

Spiro RH, Gerold FP, Strong EW. Mandibular "swing" approach for oral and oropharyngeal tumors. Head Neck Surg. 1981;3:371-378