Reconstructive Technique

The reconstructive technique chosen can include multiple modalities but the reconstructive ladder which applies to all defects is also applied in the oral cavity.

This ladder includes direct closure, closure by secondary intention, skin grafting, local flaps, regional flaps and free tissue transfer in ascending order of complexity.

Closure by Secondary Intention

Allowing the wound to granulate is an option in the oral cavity. It must be utilized however in the knowledge that the resultant contracture and scarring will not jeopardize function by compromising mobility. This is a technique which can be applied with other reconstructive options such as when an intraoral muscle flap is allowed to remucosalize. While this Chapter concentrates on microsurgical techniques for head and neck reconstruction it must not be forgotten that traditional techniques such as direct closure, skin grafting and the use of local or regional flaps are also occasionally indicated.

Free Flaps

The reliability of microvascular techniques has made free flaps the reconstructive method of choice for most large defects. Free flaps provide a versatility and diversity of choice in selecting the most appropriate reconstruction. The option of incorporating any tissue type, skin, fascia, muscle, tendon, bone, or any combination of these becomes available. The flap can be tailored to the individual not only in terms of the reconstruction but also of the donor defect left behind. Reinnervation is also an option with many of these flaps. Several flaps are in use but some stand out as workhorses for specific reconstructions. The radial forearm flap provides thin pliable, relatively hairless skin with excellent innervation potential and is by far the commonest flap used to replace intraoral lining. The fibular osseocutaneous flap is generally the flap of choice for mandibular reconstruction. It provides good quality bone in ample supply in combination with a reliable skin paddle which has excellent potential for re-innervation. These two flaps alone will be sufficient for the vast majority of intraoral reconstructions. Other flaps of course will be used and many have specific indications for reconstructing specific defects.

Floor of Mouth

Reconstruction of the floor of mouth requires thin pliable tissue. The extent of the defect will determine which technique is most appropriate. The principles outlined above all apply. Very small defects can be allowed to granulate and remucosalize or may be covered with a split thickness skin graft. Local flaps may be used to good effect in moderate sized defects. These include buccal mucosal flaps, including the facial artery musculomucosal flap (famm flap), tongue flaps and nasolabial flaps. For larger defects the radial forearm flap is reliable and widely used. It has the advantage of being thin and pliable as well as having the potential for re-innervation. The flap may be raised synchronously with the ablation. This saves operative time. Access to the floor of mouth for ablation and reconstruction is generally achieved, except for the smallest lesions, through a mandibulotomy approach. A symphyseal mandibulotomy is preferred. This allows for preservation of the mental nerves. Accurate repair of the mandibulotomy is important. This is achieved either with a plate or with lag screws. Accuracy is assured by applying the fixation before mandibulotomy: the mandible is predrilled either at the site of plate hole placement or lag screw placement. The fixation device is then removed and the mandibulotomy

is performed. At the end of the procedure the screws are merely inserted in the predrilled holes to give a perfect reduction.

When planning the reconstruction it is important to ensure that adequate tissue is provided to cover the defect and avoid any potential tethering of the tongue which can cause considerable morbidity. The defect should be carefully measured to ensure harvest of an adequately sized flap. Our flap of choice in this situation is the innervated radial forearm flap. The lateral antebrachial cutaneous nerve is harvested with the flap. Re-innervation of this flap is very efficient and it is thought to improve oral function by allowing the patient to be aware of foodstuff etc. in the reconstructed segment of the oral cavity. This not only makes eating more comfortable but allows for improved oral hygiene.

Xerostomia is one of the problems faced by oral cavity patients following radiation. In an effort to minimize this debilitating side effect jejunal patches and colon patches have been used for floor of mouth reconstruction. These flaps combine thinness and pliability with the capacity to produce mucus. While this works well, the ability of these flaps to withstand radiation is problematic. For this reason they are not widely used.

Tongue

The priorities for tongue reconstruction include airway protection, swallowing and articulation. Tongue mobility is vital for intelligible speech. As well as this the tongue helps to initiate swallowing by propelling the food bolus back into the pharynx. Functional reconstruction of such a vital and dynamic structure is very difficult to achieve. The result of the reconstruction as well as the most appropriate reconstructive choice depends on the size of the tongue resection. The larger the resection the more difficult it is to achieve normal function and the bulkier the flap required to adequately reconstruct the defect. For smaller resections, a thin pliable flap such as the radial forearm flap is ideal and is our first choice. It is important when insetting the flap to ensure that the remaining normal tongue is in no way tethered and is allowed to move optimally. The reconstruction can best be achieved by folding the flap along the lateral border of the tongue and insetting it in such a way that this part of the flap is functionally separate from the portion of the flap covering the adjacent floor of mouth. The lateral arm flap is also a useful flap for tongue reconstruction and has the advantage of being a little more bulky than the radial forearm flap. This is useful when reconstructing a hemiglossectomy defect. It has the disadvantage however of having a smaller and shorter pedicle than the radial forearm flap. It shares the potential for re-innervation with the radial forearm flap

When more than a hemi-glossectomy is carried out, the results of reconstruction become less and less rewarding. As more tongue is removed the chance of producing a mobile reconstruction is diminished. The defect produced by subtotal glossectomy with laryngeal preservation is associated with a high incidence of significant permanent swallowing problems. This is because loss of the propulsive tongue leads to a situation in which food slides down, uncontrolled. When the bulk of the tongue is removed a bulky flap is needed. In our estimation this is the ideal situation in which to use a rectus abdominis myocutaneous flap and is one of the few situations when this flap is used intraorally. The rectus abdominis myocutaneous flap has the advantage of providing bulk. This reduces the risk of inhalation and gives the patient the best

chance of regaining the ability to swallow. Functioning muscle flaps have been advocated in order to obliterate the space between floor of mouth and palate during swallowing. However a combination of the flaps discussed above represent the current gold standard.

The Pharynx

As with other areas within the oral cavity, reconstruction of the pharynx demands thin pliable cover. Again, in our practice, the radial forearm flap is the workhorse in this area. The choice of flap will be dictated by the size of the defect Other thin flaps such as ulnar artery flap, the lateral arm flap and anterolateral thigh flap have also been used successfully in this situation. Once again, the jejunum has been successfully used as a patch. As previously mentioned, the limitation of the jejunum has been its poor response to radiation

The Palate Soft Palate

The soft palate is such a dynamic structure that reconstruction is difficult and its reconstruction has traditionally been nonsurgical, a prosthesis being frequently used to obturate the palatal defect. Fitting such a prosthesis is frequently difficult and the prosthesis may be difficult to wear because of mucositis and xerostomia. This is particularly the case after radiation. Thin sensate flaps such as the radial forearm are best suited to this area. Because the flap is not dynamic however, velopharyngeal competence cannot be achieved unless the flap touches the posterior pharyngeal wall. Urken achieves this by fashioning a pharyngolpasty incorporated within his flap. For large defects, and particularly those that include a pharyngeal defect we have used two flaps in combination to close the defect; a radial forearm flap to provide pharyngeal closure with oral palatal reconstruction and a lateral arm flap anastomosed in sequence to provide nasal pharyngeal closure.

The Mandible

Mandibular reconstruction has evolved over the past 2 decades to become a very reliable though complex technique. The main reason for this advance has been the incorporation of microsurgical techniques and the development of reliable flaps for reconstruction. The concept of maintaining quality of life has become particularly important in the overall care and treatment of cancer patients. Thus, even patients with a very limited life expectancy are routinely reconstructed if it is expected that their quality of remaining life would be significantly enhanced. The high success rate of head and neck reconstructive procedures has allowed for significant improvement in both functional and aesthetic results and has completely changed the conceptual approach to mandibular reconstruction. Only patients who are medically unfit to tolerate a long operation or have a grave prognosis are excluded as candidates for resection and immediate reconstruction.

Repair of the mandibular defect most commonly includes bone as well as soft tissue with which to replace either intraoral lining, external skin or both. It is also desirable that skin used to reconstruct the inside of the mouth be innervated.

The choice of reconstruction depends on factors such as the bone and soft tissue requirements and the site of the defect. Donor site availability and morbidity, ease

of flap dissection and status of the recipient vessels in the neck as well as the patient's overall medical condition may also influence the final decision. However, while microsurgery has revolutionized mandibular reconstruction, there is still also a place for more traditional techniques. Smaller defects can sometimes be reconstructed with reconstruction plates alone, and in certain circumstances the use of nonvascularized bone is still a reasonable approach. It may even be acceptable not to reconstruct the bony defect in a small subset of patients. There is one absolute indication for vascularized bony mandibular reconstruction. That is in the central anterior mandibular defect. Using any other technique results in an unacceptable functional and cosmetic result. Many different flaps have been used for mandibular reconstruction. While the iliac crest still has a place and the radial forearm and scapiular flaps have their proponents, the fibular flap has emerged as the gold standard.

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