GENERAL CONSIDERATIONS

1. Indications
   1. The submental flap may be used for intraoral reconstruction and repair of cutaneous facial defects.
      1. See Case example Submental flap for oral cavity defect
   2. Advantages of a submental flap include its minimal donor site morbidity; excellent cutaneous color, texture, and thickness match; and pliability. The thin skin and short distance to the recipient bed are advantageous for the reconstruction of mobile oral structures, such as the tongue and floor of mouth. In men, this may be particularly useful for reconstructing hair-bearing defects.
   3. The width of the flap is determined by the laxity of the neck skin allowing primary closure ("pinch test"), and can be as large as 18 cm x 7cm. The vascular pedicle and length is designed according to the defect and can span from mandibular angle to angle if necessary, providing an arc of rotation extending from the medial canthus to the zygomatic arch.  The pedicle length can reach 5 cm when the entire facial artery is retained (ref 8c).   
2. Contraindications
   1. Circumspection is advisable in the setting of oral cavity malignancy, which may directly involve level 1 and more frequently metastasize to those lymph nodes.
   2. Prior radiotherapy to the neck will significantly compromise the viability of the flap. Though use of the flap is not contraindicated, a split thickness skin graft for closure may improve donor site closure and wound healing.
   3. Neck dissections that interrupt the submental branch of the facial artery are a contraindication to the use of this flap.
   4. The flap is relatively thin, and the need for tissue bulk is a contraindication to the use of this flap. Additional bulk may be added with inclusion of the mylohyoid muscle.
   5. For larger or more distant defects, an alternative reconstruction method or modification of this flap into a free flap should be considered.
3. Pertinent Anatomy
   1. The submental island flap is an axial patterned flap based on the submental artery. The submental artery is a consistent branch of the facial artery. It arises deep to the submandibular gland and may be deep (70%) or superficial (30%) (ref 8a) to the digastric muscle. It courses just superficial to the mylohyoid muscle as it passes forward and medially in level Ia of the neck to end behind the symphysis of the mandible. The artery then gives off a variable number of perforators that pierce the platysma muscle and supply the subdermal plexus.
   2. Caution should be exercised during the dissection as there may be only one reliable perforator off the submental artery that will ultimately supply the flap. The location of this critical perforator is variable and can be lateral or medial to the digastric muscle. A modified technique is to include the mylohyoid in the flap, thereby protecting the vascular pedicle and limiting the vascular dissection necessary (ref 8b).
   3. Venous drainage is achieved through a constant submental vein that generally drains into the facial vein. Less often, the submental vein can drain into the external jugular vein and therefore this vein should be kept flowing until the exact drainage pattern is understood.  Pre-operative evaluation of the patient's imaging may be helpful.
   4. Modifications of this flap which have been described include conversion to an osteocutaneous flap by incorporating a segment of the mandibular rim, and elongation of the pedicle by division of the facial vessels distal to the origin of the submental artery.

PREOPERATIVE PREPARATIONS

1. Evaluation
   1. A careful history and physical examination should be undertaken to determine that there has been no prior neck surgery or radiation therapy that would contraindicate the flap.
2. Potential Complications
   1. Flap failure and loss of the cutaneous paddle: Disruption of the critical perforator off the submental artery risks skin necrosis.
   2. Compromise of oncologic control: isolation of the flap pedicle may compromise the continuity of the neck dissection, particularly in the setting of oral cavity cancer and risk transferring malignant nodal tissue to the area of reconstruction
   3. Injury to the mandibular branch of the facial nerve
   4. Distortion of the contour of the jaw line will occur to some degree with the use of this flap and patients should be aware of that.

NURSING CONSIDERATIONS

1. Room Setup
   1. See Free Flap Room Setup
2. Instrumentation and Equipment
   1. Major instrument tray #1, Otolaryngology
   2. Major instrument tray #2, Otolaryngology
   3. Bipolar forceps tray
3. Medications (specific to nursing)
   1. 1% lidocaine with 1:1000 epinephrine
   2. Antibiotic ointment to incision
4. Prep and Drape
   1. Standard prep, 10% providone iodine
   2. Drape
      1. Head drape
      2. Towels to square off operative site including entire face, neck, and down onto the chest to the nipples
      3. Split sheet
5. Drains and Dressings
   1. 7 mm or 10 mm x 2 flat drains
6. Special Considerations
   1. The patient should be prepped bilaterally including the entire face, neck, and down onto the chest to the nipples.

ANESTHESIA CONSIDERATIONS

1. General
   1. The patient should not be paralyzed until after the mandibular branch of the facial nerve that will be required for the particular use of the flap is identified.
   2. The patient is positioned and, in most cases, the bed will be turned 180° from the anesthesiologist.
   3. In the vast majority of cases, the surgery is done under general anesthesia.

OPERATIVE PROCEDURE

1. The patient is placed in the supine position with the neck extended.
2. A handheld doppler is used to identify cutananeous perforators just posterior to the mandibular arch and adjacent to the anterior belly of digastric.
3. The upper border of the flap is drawn at the inferior border of the mandibular arch with inclusion of identified perforators. The maximal width of the flap is determined by a pinch test to assess how much donor site can be closed primarily. It is usually designed in an elliptical fashion.
4. The submental flap is generally raised before lymphadenectomy. A subplatysmal dissection is carried out until the ipsilateral submandibular gland and bilateral anterior belly of the digastric are identified. The facial and submental vessels are identified deep to the superior aspect of the gland, and are skeletonized with the subplatysmal skin island up to the lateral border of the mylohyoid. Care is taken to identify and protect the marginal mandibular nerve.
5. Once the submental vessels are visualized until they proceed under the anterior belly of the digastric, the flap can be raised from distal to proximal. The contralateral aspect of the flap can be raised either in a sub-platysmal or supra-platysmal plane (this can reduce the risk of injury the the contralateral marginal mandibular branch but may reduce vascularity to the distal tip)
6. The overlying segment of the ipsilateral anterior belly of the digastric muscle is dissected off the mandible and the hyoid bone and included with the flap to protect the terminal vascular supply as it passes deep to the muscle.
7. The underlying mylohyoid muscle is either cut or a strip is included with the pedicle if the flap needs to be tunneled medial to the mandible for intraoral reconstruction. The mylohyoid is detached from the mandible and the hyoid and is bluntly dissected off the ipsilateral geniohyoid muscle to complete the flap mobilization
8. The remaining neck dissection is performed with preservation of the facial vessels and the internal  jugular vein.
9. The flap is tunneled subcutaneously or intraorally depending on the location of the defect.
10. Depending on the location of the defect, it may be necessary to perform several maneuvers to increase arc of rotation. This includes dividing the facial artery and vein distal to the take off of the submental vessels. Division of the posterior belly of the digastric and skeletonizing the vessels to the external carotid and internal jugular vein can also improve reach. If necessary, the facial vein may also be divided and re-anastamosed using microvascular techniques to a vein (i.e. retromandibular vein) closer to the defect.
11. Closure is performed in the usual fashion for neck dissection, utilizing suction drains. Wide undermining of the inferior flap may be necessary to achieve tension free closure.  This must be kept in mind in patients requiring tracheostomy.

POSTOPERATIVE CARE

1. Drains are removed when the output is less than 30 ml per day.
2. Tension on the flap is minimized if the patient’s head is turned toward the donor side. This should be reinforced in the postoperative orders and accomplished with pillows or sandbags.

REFERENCES

Parmar PS, Goldstein DP. The submental island flap in head and neck reconstruction. Curr Opin Otolaryngol Head Neck Surg. 2009 May 14. Epub ahead of print

Patel UA, Bayles SW, Hayden RE. The submental flap: A modified technique for resident training. Laryngoscope. 2007 Jan;117(1):186-9.

Sebastian P et al. The submental island flap for reconstruction of intramural defects in oral cancer patients. Oral Oncology (2008) 44, 1014-1018