16 Reconstruction of the Oral Tongue
Reconstruction of the oral tongue is essential for restoration of speech and swallowing function following resection of both benign and malignant tumors. This chapter outlines the pertinent anatomy, principles of reconstruction, and the reconstructive options based on the location and size of the ablative defect. Locoregional and free-flap reconstruction options and functional outcomes of each flap are discussed.
Reconstruction of the oral tongue is critical for maintenance of quality of life as the oral tongue is essential for articulation, mastication, and swallowing. Extirpation of benign and, more often, malignant tumors is the indication for reconstruction in the majority of cases. The type of reconstruction depends on the type and extent of the tumor, involvement of other subsites of the oral cavity and oropharynx, and patient factors including comorbid conditions, body habitus, and prior radiation therapy. Overall, the goal of reconstruction is to close the oral defect and restore volume to the oral tongue to assist with articulation and swallowing.
16.2 Diagnosis and Evaluation
Consideration of several factors is essential to determine the type of reconstruction necessary for an individual patient. Tumor location is an important consideration for tongue reconstruction, as removal of tumors of the tip of the oral tongue tends to produce more difficulties with articulation than tumors involving the lateral tongue. Size of the tumor and involvement of other oral cavity or oropharyngeal subsites will influence the decision of the type and extent of reconstruction. Finally, prior radiation therapy of the oral cavity and neck will limit the use of local and regional flaps, thus limiting the reconstructive options.
Physical examination of the oral cavity should consist of determining the location of the tumor, involvement of adjacent subsites such as the floor of the mouth, mandibular alveolus, retromolar trigone, and base of tongue, and estimation of the depth of the tumor. The ipsilateral buccal mucosa is evaluated for the presence of tumor and scars for consideration of regional flap reconstruction. The presence or absence of teeth is also important for reconstructive planning. The laxity of cervical skin, the presence of scars from prior surgeries or injuries, and radiation fibrosis should be assessed to determine the feasibility of local and regional flap reconstruction. For anticipated defects greater than 50% of the oral tongue, or if multiple subsites are involved, free-flap reconstruction is preferred. Allen’s test of the patient’s nondominant hand, palpation of the lateral thigh skin, evaluation of the skin and subcutaneous tissue overlying the abdomen, and palpation of the skin and muscle overlying the latissimus dorsi muscle are performed to determine the best potential free-flap donor site.
Diagnostic imagining is imperative for comprehensive determination of tumor involvement and tumor thickness. MRI provides the best soft-tissue resolution; however, CT scan can provide adequate resolution for tumor extirpation and reconstruction, and it is the preferred modality to asses for bone invasion.
16.3 Anatomic Considerations
16.3.1 Oral Tongue Musculature
The oral tongue consists of intrinsic and extrinsic muscles covered by a mucosal membrane. The subsites of the oral tongue include the tip and the body of the tongue. The body of the tongue is divided into dorsal and ventral components in the axial plane, and into lateral halves in the sagittal plane separated by the median sulcus. The posterior aspect of the oral tongue is the terminal sulcus, indicated by the circumvallate papillae.
There are four intrinsic muscles of the tongue: superior longitudinal, inferior longitudinal, transverse, and vertical muscles. They have no bony insertion and act to alter the shape of the tongue. The extrinsic muscles include the genioglossus, hyoglossus, styloglossus, and palatoglossus. These muscles originate outside the tongue and insert within it to change tongue position. Deep to the extrinsic muscles is the mylohyoid muscle, which provides a diaphragm for the oral cavity contents. While it is not a muscle of the tongue, involvement of the mylohyoid and removal for safe oncologic margin affects the reconstructive design due to the potential for ptosis of the oral cavity contents postoperatively.
The main blood supply is from bilateral lingual arteries arising from the external carotid artery. The lingual arteries travel deep to the styloglossus muscle traveling superomedially and then altering course traveling anteroinferiorly. The main branches of the lingual artery are the dorsal lingual artery, the deep lingual, and the sublingual arteries. The dorsal lingual artery supplies the base of the tongue, while the latter two supply the oral tongue. Knowledge of the vascular anatomy of the tongue is important for both the ablative surgeon and the reconstructive surgeon. Adequate hemostatic control of the dorsal lingual artery is imperative to prevent potential catastrophic hemorrhage postoperatively.
The major motor innervation to the tongue is the hypoglossal nerve. The only exception is the palatoglossus, which is innervated by the vagus nerve. The sensory innervation of the tongue via the lingual nerve is a more important consideration for the reconstructive surgeon if there is a plan for tongue sensory reinnervation. This will be discussed in more depth in section 16.4.5.
16.4 Surgical Considerations and Approaches
16.4.1 Reconstructive Options
The type of tongue reconstruction depends on the location and the size of the defect. Often, small benign and malignant lesions can be left to heal by secondary intention. Small defects in the ventral tongue and floor of mouth should not be allowed to heal by secondary intention, as there is the potential risk of scarring and tethering of the tongue. Skin grafts are an option and are well reported in the literature. 1 Skin grafts require bolsters to ensure graft viability on the dynamic tongue musculature, and with their use airway compromise must be avoided.
Defects that leave a large surface area of the tongue exposed but not large enough to produce a significant reduction of tongue volume greater than approximately one-third of the tongue 2 can be partially or completely closed primarily with absorbable sutures. Mobilization of local tongue mucosa and musculature with a local flap is also an option to aid in closure. However, too much tissue rearrangement results in impaired function with no correction for the loss of tongue volume.
There are many regional pedicled flaps and free flaps that are available for defects spanning one-third to one-half of the oral tongue. The regional pedicled flaps include the submental artery island flap, facial artery myomucosal flap, supraclavicular artery island flap, temporalis muscle flap, and the pectoralis major myocutaneous flap. Free flaps such as the radial forearm free flap (RFFF), the anterolateral thigh (ALT), and the gracilis myocutaneous free flap can also be used for both smaller defects of one-third to one-half of the oral tongue.
For defects greater than or equal to half of the tongue, larger volume flaps such as the ALT, latissimus dorsi, thoracodorsal artery perforator, upper lateral arm, or rectus abdominis free flaps are necessary to fill dead space. Pectoralis major myocutaneous pedicled flaps can also be used, but are generally reserved for salvage cases. Please refer to ▶ Table 16.1 for a list of tissue options for oral tongue reconstruction based on defect size and location.