The diameter of the tongue and/or the floor of the mouth is more than 2 cm, the margin of the tongue does not reach the midline or the cancers in the body of tongue, and the tip of the tongue has a range of infiltration which does not exceed the V-shaped sulcus.

The cancers in the tongue and/or the floor of the mouth which invade the gingiva and the upper one-third of the mandible or the cancers with suspected invasion.

The cancers in the tongue and/or the floor of the mouth with N₀ cervical metastasis foci and the ipsilateral functional cervical lymph node dissection and the repair with subhyoid myocutaneous flap can be performed.

The patients with N₁-N₂a cervical metastasis foci should undergo ipsilateral radical cervical lymph node dissection and repair using subhyoid myocutaneous flap with venous anastomosis, and other skin flaps can also be used to repair the tongue defects. If the patients have ipsilateral-negative lymph nodes and contralateral cervical metastasis foci, they should undergo ipsilateral functional cervical lymph node dissection, contralateral radical cervical lymph node dissection, and the repair with subhyoid myocutaneous flap, and other skin flaps can also be used to repair the tongue defects.

Preoperative preparation

Anesthesia. The patient receives the intranasal intubation combined with compound intravenous general anesthesia.

Body position. The patient lies on their back, with a pillow under the shoulder and the head toward the healthy side, and the urethral catheter is placed in advance.

Disinfection and draping. Both eyes are smeared with chlortetracycline eye ointment, and small cotton balls are stuffed into bilateral external auditory canals. Complex iodine is used to disinfect conventionally the surgical areas such as the head, neck, chest, and shoulders for three times. The aseptic towel, medical bed sheet, and quilt with a hole are draped.

Incision. The upper and lower transverse incision lines of the subhyoid myocutaneous flap are made at first, and the length is 4.5 cm; then the inner and outer vertical incision lines are made; the length is 6 cm (Fig. 6.3).The lower incision line of the skin flap is extended to reach the medial side of the shoulder joint. A stepped line from the midline of the lower lip is made downward to intersect with the inner incision line of the skin flap, then the lower buccal gingival sulcus incision at the affected side is incised, and the facial and cervical skin flap is turned over to the affected side to complete the primary tumor resection and the cervical lymph node dissection. In the subhyoid area, 6 × 4.5 cm of anterior cervical skin is prepared for use as the subhyoid myocutaneous flap. In general, the skin defect in the donor site of the skin flap can be closed and sutured directly. The skin below the clavicle is harvested to be used as the thoracic transverse fascia skin flap to repair the larger skin defect at the anterior cervical donor site.

Separation of facial and cervical skin flap. Incise open the skin along the midline of the lower lip downward to the upper incision line of subhyoid myocutaneous flap and the lateral incision line to the clavicle, and transversely incise the upper incision marker line of the thoracic transverse fascia skin flap in the level of the clavicle. Along the deep surface of the platysma muscle and the superficial face of the deep cervical fascia, turn over the skin flap from the lower inner side of the facial and cervical skin flap toward the upper outer side, the upper boundary reaches the lower margin of the mandible, and the outer boundary reaches the anterior margin of the trapezius muscle. Ligate off the transverse cervical artery and vein at the lower margin of the mandible. Attentions should be paid to protecting the marginal mandibular branch of the facial nerve. Incise open the periosteum along the lower margin of the mandible; ligate and cut off the submental artery and vein; cut off the attachment point of the musculi masseter in the mandibular angle. The skin flap in the face and neck is separated to the level of the gingival cheek groove and labiogingival groove.

Elimination of posterior cervical triangle. Pay attention to separately dissecting and protecting the external jugular superficial vein and its small branches for standby application. Incise open the anterior margin of the trapezius muscle; separate and reserve the accessory nerve; dissociate along the long axis of this nerve toward the anterior upper inner side, upward to the site where the accessory nerve gives off the sternocleidomastoid branch, and downward to the inner surface of the trapezius muscle. Dissect the adipose tissue within the supraclavicular fossa; cut off the nervi supraclaviculares (two to three branches); separate the shoulder end of the omohyoid muscle; cut it off after clamping; cut off the transverse cervical artery and vein; dually ligate the broken ends. Along the superficial surface of the prevertebral fascia, from the bottom up and from the rear to the front, dissect forward from the posterior triangle to the site below the rear edge of sternocleidomastoid. It is observed in the upper parts of the front and middle scalene muscles that the cervical plexus cutaneous nerves penetrate out of the deep fascia, from top to bottom in turn for the lesser occipital nerve, great auricular nerve, anterior cervical nerve, and supraclavicular nerve, which are cut off at 0.5 cm away from their penetrating out sites. The phrenic nerve runs from the outer upper side toward the inner lower side at the surface of anterior scalene muscle, the brachial plexus nerves penetrate out from the scalene fissure, both kinds of nerves are located at the deep surface of the prevertebral fascia, and attentions should be paid to protecting them from damage. When the proximal end of the transverse cervical artery is ligated, it should be noted that the cupula pleurae is not damaged.

Removal of internal jugular lymph node chain. Incise open at the anterior and posterior margins of the external jugular vein, separate this vein from the sternocleidomastoid muscle, and then reserve it. If there are communicating branches running to the anterior jugular vein above the level of the hyoid bone, they should be retained to be used as the reflux veins. If the external jugular vein has no branches communicating with the subhyoid myocutaneous flap, it is supposed to retain one to two small branches with a diameter of about 2 mm. When the subhyoid myocutaneous flap with venous anastomosis is formed, they can be used as the anastomosed reflux veins of the receptor site.

Sharply incise the superficial layer of deep cervical fascia from the anterior margin of the sternocleidomastoid muscle, adopt the dissociation method of overturning the sternocleidomastoid muscle, dissociate at the middle of this muscle from the inner to the outer edge, and separate the muscle belly with the deep soft tissue. Then, lift the sternocleidomastoid muscle with a drag hook, and dissociate the sternocleidomastoid muscle all the way at the deep side of the muscle belly, up near the end of the mastoid process, and down near the clavicle. The muscle at the sternal head of sternocleidomastoid muscle can be cut off, which is retained in the subhyoid myocutaneous flap. The sternocleidomastoid muscle is pulled outward to expose the cervical vascular sheath (middle layer of deep cervical fascia or called as the visceral fascia); the sheath membranes of cervical blood vessels are incised open starting from the inner margin of the internal jugular vein; the internal jugular vein, carotid artery, and vagus nerve are separated out; the internal jugular vein is completely exposed to be removed completely. Reach the prevertebral fascia at the deep side of the internal jugular vein, and thereby outwardly remove the soft tissue mass in the lateral area of the internal jugular vein, including soft tissues upward from the posterior belly of digastric muscle, downward to the clavicle, and outward to anterior margin of the trapezius muscle, the musculus levator scapulae, and the scalene muscle in the base surface and the deep surface of the sternocleidomastoid muscle in the front surface. It should be noted that it is required to protect the superior thyroid artery and vein when the sternocleidomastoid muscle is dissected. The thoracic lymph duct pours into the left jugular venous angle; the right lymphatic duct pours into the right venous angle. Before pouring into jugular venous angles, both lymphatic ducts collect lymphatic fluids, respectively, from the left and right subclavian trunks as well as the left and right jugular trunks, and thus these soft tissues should be clamped before being cut off and sutured. When the lymphatic fluid outflow is observed, a few stitches should be additionally performed to prevent the chylous leakage. The carotid triangle area is dissected after the subhyoid myocutaneous flap is formed.

Removal of submental and submandibular triangle areas. The submental and submandibular triangle areas are conventionally removed, and the specimens and primary tumor are resected and then are cleared away together. In addition, a part of the lower pole of the parotid gland is resected at the horizontal level of the mandibular angle, and its broken end is sutured to prevent postoperative parotid fistula.

Resection of primary foci. Cut open the mucosa to the molars at the gingival cheek groove, and then further turn over the facial and cervical skin flap. Strip off the periosteum at the inner surface of the mandible to the attachment site of mylohyoid muscle, and cut off the attachment site with an electric scalpel. A rectangular resection is performed in the mandible body, and the invaded tissues in the tongue and floor of the mouth are removed. Pass through a thread, respectively, on the left and right sides of the tongue tip to pull the tongue out of the mouth to the greatest extent; reach the site of circumvallate papillae along the midline from 2 cm at the outer edge of the tumor; resect the tissues in the affected floor of the mouth in the safe range to the V-shaped sulcus terminalis; transect half of the tongue; ligate the lingual artery; the removed half of the tongue and mouth floor tissue are connected to the mandibular bone block of rectangular resection. A pair of pliers is inserted into the buccal passageway in the inner surface of the affected mandible to grip the suture line which is placed in advance in the affected tongue tip; pull downward the separated and affected tongue; the mouth floor tissue and the mandibular bone block to the cervical area through the buccal cervical passageway. In this way, the affected tongue, mouth floor tissue, rectangular bone block, submandibular triangle, and submental triangle jointly constitute a whole piece of surgical specimen to be removed.

Formation of subhyoid myocutaneous flap. After removal of surgical specimen, the careful hemostasis is performed, and the hydrogen peroxide solution and the normal saline are used to wash the surgical cavity. The subhyoid myocutaneous flap is harvested for repair according to defect size. The subhyoid myocutaneous flap should be designed in the anterior cervical area at the defect side, and the area of the skin flap is 7.0 × 4.5 cm. After that, the skin and subcutaneous tissues are incised along the inner incision and lower incision of the skin flap. When the subhyoid myocutaneous flap is harvested, the separation should be started from the distal end. The pectoralis major fascia and the sternal head of sternocleidomastoid muscle may be included within the myocutaneous flap, the muscular fascial blood vessels at the surface layer of sternocleidomastoid muscle should be carried onto the skin flap, and the blood vessels of sternocleidomastoid branches are retained. The anterior jugular vein is ligated and cut off, and the lower end of the strap muscle is cut off. The broken ends of the muscle are sutured and fixed with the skin by a few stitches to prevent tearing off of the skin flap from the muscle. Separate along the outside of the true envelope of thyroid gland. When reaching the upper pole of the thyroid gland, don’t excessively separate the upper pole of thyroid tissues with the anterior muscles of the skin flap to prevent damage to small supplying arteries. The anterior branch of the superior thyroid artery is retained behind the sternothyroid muscle and is ligated and cut off at the site near the midline. The blood vessels and a portion of the thyroid tissue of the upper pole of the thyroid gland are retained in the vascular pedicle of skin flap. The residual stump of thyroid gland is sutured and ligated. The ending point of sternothyroid muscle on the thyroid cartilage is cut off, and it is noted that the external branch of the superior laryngeal nerve is not damaged. When the separation is performed continuously upward, the myolemma at the superficial surface of thyrohyoid muscle is retained onto the skin flap so as to increase the blood supply.

Upon completion of skin flap harvesting, the subhyoid myocutaneous flap is transferred into the defect area in the receptor site through the buccal cervical passageway at the inner side of the mandible, and the length of the skin flap is measured to evaluate whether it can meet the requirements of the receptor site. For the patients in whom the pedicle has no tension after the skin flap reaches the receptor site, the subhyoid myocutaneous flap with arteriovenous pedicle is formed, and this skin flap has two reflux veins such as external jugular superficial veins and superior thyroid vein. On the contrary, for the patients in whom the short skin flap with superior thyroid vein cannot reach the receptor site, or the patients in whom the large tension in the pedicle causes the circumfluence obstacle of the superior thyroid vein, it is needed to cut off the superior thyroid vein from the internal jugular vein, and the crevasse of the internal jugular vein is sutured with the needle and thread causing no damage to form the subhyoid myocutaneous flap with the superior thyroid vein and external jugular superficial vein (facial vein).

Repair of defects in the tongue and floor of the mouth. The proximal end of the prepared subhyoid myocutaneous flap is sutured to the root of the tongue and repair the floor of the mouth, the distal end is taken as the front portion of the tongue, and the buccal mucosa and lower lip are sutured. The anterior cervical defect can be directly sutured with gliding method, and it can also be repaired with the ipsilateral transverse thoracic fascial flap. The key point in harvesting the thoracic fascial flap is to include the pectoralis major fascia into the skin flap, and it is preferable to damage the pectoralis major muscle fibers rather than damage its muscular fascia.

Improvement of surgical methods. The subhyoid myocutaneous flap pedicled with the external jugular superficial vein and the superior thyroid vein is taken as an example, with reference to traditional surgical procedures of the subhyoid myocutaneous flap, but there are the following exceptions:

Investigation of the cause for skin flap necrosis. It is reported in the literatures at home and abroad that the necrosis rate of the myocutaneous flap is 7–47%, and the analysis shows that it is mainly due to the venous flow obstruction caused by the short venous pedicle of the skin flap. Therefore, the following three points should be considered when the skin flap is designed: