Head and Neck Reconstruction




Introduction


The head and neck is a unique anatomic region of the human body with specialized function. The sophisticated arrangement of multiple tissue types comprises unique physical traits from individual to individual. Regions of the head, face, and neck are responsible for multiple high functioning mechanisms, including mastication, swallowing, phonation, articulation, respiration, vision, periorbital protective mechanisms, audition, and olfaction, all of which have been characteristic in the evolutionary development of man. Moreover, interpersonal communication and recognition of social cues are all delivered and interpreted via facial contour and movement. The subtleties of facial anatomy contribute to individual identity, and although phenotypic differences are recognized among ethnicity, sex, and various individuals, there is an overarching commonality of features that permeates a sense of normal . Understanding these relationships, patient expectations, and the limits of reconstruction are certainly enhanced with surgeon experience in the treatment of craniofacial injury and deformity. However, a systematic approach to craniofacial reconstruction that abides by several tenets is essential in optimizing outcomes. Unlike other regions of the body, aesthetic outcomes may be just as important as functional outcomes in the head and neck due to the social implications of deformity.


The deformities of the head or neck are often the result of trauma, oncologic resection, infection, osteoradionecrosis, and congenital or developmental pathology. Multiple tissue types that compose the craniofacial region including bone, cartilage, nerve, fat, muscle, mucosa, and varying dermal and epidermal thickness, as well the inherently intricate contours of the craniofacial skeleton can complicate reconstruction. However, significant advances in microvascular and craniomaxillofacial surgery over the past 50 years have resulted in dramatically improved outcomes. The purpose of this chapter is to provide a methodological approach to microvascular reconstruction of the head and neck while optimizing aesthetic and functional outcomes, as well as developing an effective means of achieving reliable and replicable results. The workhorse flaps used in reconstructing the various regions of the head and neck are described with an emphasis on their application to the craniofacial segments, their advantages, and disadvantages.




Preoperative Considerations


As with all reconstructive procedures, meticulous assessment of wounds and careful reconstructive planning are essential to achieving successful outcomes. However, strict adherence to several critical principles specific to the demands of craniofacial surgery is paramount to addressing complex injury or deformity of the head and neck. These concepts are:




  • Aesthetic subunit appearance



  • Defect boundaries



  • Tissue requirements



  • Establishment of a skeletal buttress framework



  • Generous soft tissue volume



  • Early or immediate reconstruction



  • Local revisions through multi-stage planning



Consideration of these principles is essential in attaining a functional and aesthetic outcome that is predictable and reproducible. A methodical structure to plan and perform segmental or multi-segment craniomaxillofacial reconstruction of composite defects provides consistency in surgical approaches and optimizes flap selection. Furthermore, these principles mark a paradigm shift in head and neck reconstruction as they synthesize an amalgam of advancements from aesthetic surgery, craniofacial surgery, trauma surgery, and radiation, wound, and scar biology.




Critical Concepts of Craniofacial Microvascular Reconstruction


Aesthetic Subunit Appearance


It is well established that replacing “like with like” is the gold standard of aesthetically pleasing reconstructions. However, this is often difficult to achieve because the face can be divided into discrete aesthetic subunits based on variations in skin texture, color, thickness, and histology. Injury can affect multiple subunits or portions of subunits that makes flap selection more challenging. Understanding the lines of demarcation between facial segments and appreciating the variation in skin thickness throughout the face can aid the surgeon in using skin grafts from areas with similar characteristics to the site being reconstructed. Pioneered by Mario González-Ulloa, these concepts permeate throughout multiple facets of plastic surgery but were lacking in early microvascular surgery of the head and neck. Perhaps, these principles were considered secondary because early microvascular flap failure rates were initially too high. Over time, advancements in technique and instrumentation have precluded the surgeon from simply trying to reconstruct a defect by “filling a hole,” and have permitted restoration of entire aesthetic subunits, even when removing healthy tissue may be required. This allows the surgeon to achieve superior reconstruction with concomitant consideration of cosmetic results.


It is imperative to recognize that aesthetic facial subunits are not just “skin deep.” Each facial region is comprised of vertical and horizontal skeletal buttresses that provide critical soft tissue support and shape. In addition, the subcutaneous fat is partitioned into discrete compartments of the face, a concept championed in cosmetic facial surgery. The perception of facial aesthetic subunit is actually dependent on multiple elements, representing an amalgam of interactions between composite soft and hard tissue. Therefore, a “defect-oriented approach,” in which a soft tissue-only flap is used to solve the immediate goal of wound closure will often result in suboptimal cosmesis. Reconstructing a composite tissue defect of an aesthetic subunit of the face with free tissue transfer requires the necessary elements that are absent in a wound including the underlying skeletal support with the coverage of soft tissue.


Defect Boundaries


Rearrangement of defect boundaries affords the surgeon several benefits toward improving outcomes. First, the wound edges of various defects are prone to infectious complications and if not maintained in a pristine environment, the wound is prone to desiccation and breakdown. Expansion or rearrangement of wound borders allows for a decreased microbial burden and a healthy wound edge comprised of collagenous, elastic, and a well-vascularized environment facilitating better wound healing. Second, the dogmatic principles of aesthetic subunit reconstruction dictate that certain defects can be made larger in order to resurface the entire unit. This allows for incisions to be hidden in skin creases and behind or within specific structures. For defects that comprise >60% of an aesthetic subunit, resection of the entire subunit may be indicated since free flap reconstruction can reconstruct the expanded defect and achieve superior cosmetic results. Flap homogeneity throughout the entire subunit conforms to a more uniform distribution of color, thickness, and texture while disguising incisions at the junctions of subunits. This is depicted in Figure 14.1 , where a large forehead defect prompts extension of the borders of resection, making the forehead defect larger than initially encountered. Free tissue transfer allows for scars to be hidden in the pretrichial hairline and just superior to the eyebrows.




Figure 14.1


(A) Wound covered with silver-coated dressing with preoperative markings showing extension of the wound boundary. (B) Iatrogenic extension of the wound boundaries allows for the incision line to be hidden in the hairline.

(Reprinted from Fisher M, Dorafshar A, Bojovic B, et al. The evolution of critical concepts in aesthetic craniofacial microsurgical reconstruction. Plast Reconstr Surg 2012;130:389–98. Wolters Kluwer Health, 2012.)


The concept of extending the boundary of defects when >60% deformity to an aesthetic subunit is present, is not absolute. The inherent characteristics of the subunit at hand must dictate the reconstructive effort because not all aesthetic subunits are as easy to re-create as others with free tissue transfer. For example, re-creation of the vermillion lip is challenging, since no autologous free flap options exist to re-create a satisfactory semblance of the subunit. In the case of a partial vermillion lip defect, resection and replacement of the entire unit would not result in a superior aesthetic outcome. When considering resection of additional local tissue the degree of resection may be dictated by plans for future revisionary procedures. In order to achieve total aesthetic subunit reconstruction, the option for potentially advancing local cutaneous tissue with successive revisionary procedures (or with tissue expansion) can lead to complete excision of the initial free flap skin paddle and reestablish the native skin of the original defect. This concept is further discussed in the revisionary procedures portion of this chapter.


Tissue Requirements


Adhering to the principles of replacing missing components such as bone, soft tissue, or oral lining can guide the surgeon in planning and executing the replacement of “like with like” tissue to herald better results. The concept of considering the tissue types and establishing their continuity or obliterating an apparent discontinuity is particularly important when some form of “lining” tissue (e.g., conjunctiva, nasal mucosa, sinus mucosa, or oral mucosa) is deficient. Failure to provide an adequate lining can severely compromise results after free flap reconstruction, leading to contracture, fibrosis, and chronic infection. Meticulous preoperative planning and anticipation for such defects, although not initially obvious can help the surgeon to better predict which tissue types are deficient. Furthermore, reconstructions should be predicated on re-creation of the defect, especially in cases of delayed reconstruction where scarring and contracture may have obscured the initial defect, making it more difficult to appreciate a lining deficiency. The choice of free flap should not only include the adequate components required for skin coverage, soft tissue bulk, and skeletal support, but also a surplus of skin, fascia, or muscle that can be used to provide lining. This approach ensures that all lining deficiency is addressed. The importance of restoring tissue types and their subsequent continuity was stressed in the early years of plastic surgery by Gillies and Keegan, but despite the importance stressed on such structures by the pioneers of plastic surgery, the need for lining reconstruction is still often underestimated by contemporary microvascular surgeons.


Bone and Soft Tissue Support


It is imperative that the microsurgeon address the need for hard tissue reconstruction in free tissue transfer. When facing a large composite facial defect in which both bone and soft tissue are missing, selecting a flap consisting of abundant soft tissue rather than both bone and soft tissue is not recommended. This approach succeeds in “filling the hole,” but falls short of the fundamental reconstructive goal of replacing “like with like.” The importance of skeletal structure as a means of providing structural support and aesthetic guidance anchoring soft tissue has been well described by Rodriguez and colleagues by preserving craniofacial skeletal buttresses. Emphasis on skeletal reconstruction has largely been championed by craniofacial surgeons, but restoration of the deficient soft tissues may be overlooked when skeletal reconstruction is overemphasized. With the synthesis of microsurgery and craniofacial surgery, surgeons now recognize the importance of reconstructing both soft and hard tissue. The advent of prosthetic implants, fixation plates, and non-vascularized bone grafts has bridged the surgeon’s understanding of the crucial relationship of bony stabilization and soft tissue re-draping. Options for reconstructive approaches may seem vast at times, but a means of providing an optimal relationship of hard and soft tissue, similar to the premorbid state, should drive the decision-making process.


Historically, non-vascularized bone grafts were the mainstay of bony reconstruction and still have a limited role in treatment of small skeletal defects. The disadvantage of non-vascularized bone grafts includes unpredictable resorption rates and the inability to replace large structural defects. The unfortunate result of excessively using non-vascularized bone grafts for inappropriately sized defects will necessitate further reconstructions over time. Additionally, bone grafts generally provide insufficient bone stock to allow placement of osseointegrated implant prostheses. In certain cases, craniofacial bone defects can be reconstructed with an allo­plastic implant covered by a vascularized soft tissue flap. However, successful incorporation of alloplastic material requires wide debridement and clearance of marginal tissue edges to minimized dehiscence and infection. Osteoradionecrosis and prior chronic infections are not absolute contraindications for using alloplastic material, but the surgeon must be vigilant in ensuring the maximal removal of any infectious burden to the defect. Alloplastic materials are prone to late infection and tend to extrude over time, leading to implant exposure. Undoubtedly, situations will call for wider resection of the wound and acknowledging that sacrificing tissue cannot be afforded to certain defects may preclude the use of prosthetic materials for reconstruction. As with non-vascularized bone grafts, the long-term complications may require further surgical interventions later down the line. Vascularized bone obviates many of the unforeseen complications that are associated with non-vascularized bone grafts and alloplastic materials, and therefore should be used for hard tissue reconstruction whenever possible. Adequate soft tissue and bone can often be incorporated in the same free flap; however, multiple flaps may sometimes be required to provide sufficient quantities of both types of tissue.


Soft Tissue Volume


The soft tissue volume included in a free flap should be in slight excess of the actual amount of tissue that is deficient. If postoperative radiation therapy is anticipated, the excess volume should be further increased, since significant soft tissue contraction can result from radiation exposure. The degree of soft tissue resorption and atrophy is unpredictable. Including excess soft tissue affords the surgeon insurance of coverage in the event of excessive contracture or atrophy. It is always easier to debulk excess soft tissue at a later stage than to add volume secondarily. The inclusion of ample volumes of well-vascularized fat in particular will minimize subsequent fat necrosis and soft tissue resorption. Healthy adipose tissue will also provide the necessary volume for future revisionary reshaping procedures as the transferred tissue settles. Options for debulking via direct excision and/or liposuction in a revisionary procedure allow the surgeon to focus on cosmesis after the initial healing period and after flap survival is assured. In contrast to adipose tissue, denervated muscle flaps tend to atrophy significantly over time, compromising long-term aesthetic outcome and failing to provide durable coverage for alloplastic implants. For example, latissimus dorsi muscle flaps have been considered the workhorse flap and traditional choice for scalp coverage of titanium mesh cranioplasties, but such flaps have shown to thin significantly over time, often resulting in tenuous coverage or ultimate exposure of the underlying mesh.


Selection of the donor site for free soft tissue transfer must be guided in a patient-centered, individualized basis. Patient-specific needs must be considered in the risk–benefit analysis of selecting a flap, especially in the elderly, with respect to donor site morbidity, those with physical disabilities, and in the actively growing young person. A color match and the compatibility between donor site soft tissue volume and recipient site soft tissue deficit then becomes the priority. For instance, the variability in subcutaneous fat among patients is apparent when considering an anterolateral thigh (ALT) flap. Although some advocate aggressive thinning of the ALT flap at the primary stage, this practice is not recommended for craniofacial reconstruction. It is preferable to err on the side of caution with a thicker flap, which can be debulked secondarily.


Timing


In the face of trauma or oncologic resection, the microsurgeon must not prolong the time to reconstruction. Reconstructing the injury acutely minimizes the cascade of scar formation associated with the initial injury and confines the deleterious effects to a single period of postoperative wound contracture. The advantages of initiating early free tissue transfer to avoid these effects are two-fold. First, dissection of the recipient site and its vessels is simplified when not operating in a scarred bed. Second, the functional and cosmetic results of the reconstruction are improved by reducing the overall scar burden of the soft tissues in that area.


In the approach to congenital deformity reconstruction, the timing for intervention differs since there is no scarring associated with creation of the initial defect. In these instances, delaying surgery to an extent may be more appropriate for the patient. Determining time to intervention is on an individualized basis because of multiple factors and comorbidity issues to contemplate. Ongoing child development and whether he or she will ultimately “outgrow” their free flap reconstruction is difficult to predict, which significantly contributes to the decision-making process of timing reconstruction. Additionally, the distribution of body surface area differs in the pediatric patient, as the head compromises a greater percentage of the total surface area. Ensuring ample tissue may be a challenge in the pediatric patient, especially when considering free tissue transfer to the pediatric craniofacial region. For example, a latissimus dorsi flap can easily cover a large adult scalp defect, but it may not provide sufficient size for coverage in the pediatric patient. A final concern that may affect timing of reconstruction is the practical consideration of vascular pedicle size. The microsurgeon must understand one’s limitation when dealing with smaller-caliber vessel anastomoses. At this level of complexity, although feasible, successful outcomes may vary in each individual surgeon’s hands.


Secondary Revisions


Secondary revisions must not be considered failure of the initial surgery, but instead be incorporated in the overall reconstructive approach as a method of optimizing outcomes. There is often an impetus to minimize the number of reconstructive procedures a patient requires. As a result, microsurgeons attempt single-stage procedures aimed at definitive reconstruction. However, this approach will generally compromise long-term outcomes due to skin color mismatch and soft tissue contracture. Ambitious single-stage procedures do not capture all of the tools in the plastic surgeon’s armamentarium in solving large craniofacial defects. With the understanding that secondary revisions are often inevitable in optimizing complex defects, the initial reconstructive procedure no longer assumes the burden of complete reconstruction but is the first of multiple approaches.


Secondary revisions are fundamental for achieving successful reconstruction of the facial aesthetic units since injury is likely to cross multiple subunits and resultant scar, contracture, and contour and color mismatch are much more pronounced to the lay observer. The aforementioned concept of aesthetic subunits and establishing homogeneity of skin characteristics is reiterated as the eventual need for revisionary procedures should be anticipated at the time of the initial free tissue transfer. In accordance with the concept of defect boundaries, if a defect comprises <60% of the unit, maximal preservation of local surrounding tissue is required, as it may be successively recruited with local tissue rearrangement during secondary procedures. If the previously mentioned concept of soft tissue is employed, the initial free flap should include excess soft tissue, which can later be debulked, shaped, and ultimately covered by local cutaneous advancement. For example, consider a cheek defect comprising 40% of the aesthetic unit being reconstructed with a free ALT flap. Excision of the entire unit during the first reconstruction is not ideal because this leaves an obvious area of color-mismatched and hair-bearing skin, demarcating a stark contrast of the cheek aesthetic unit. Recruiting distant tissue transfer serves as a base for local tissue advancement and resurfaced to provide a more favorable cutaneous texture and color match. The foresight of future revisions allows initial free tissue transfer to be planned and executed with more success. In this case, the free flap can be selectively de-epithelialized and the remaining dermis can serve as a substantial anchor from which to re-suspend advanced local skin.


Other secondary procedures may include dermabrasion, soft tissue re-suspension, excision of soft tissue, suction lipectomy, and fat grafting. At this juncture, skin excision from the free flap with full-thickness skin grafting from a donor site similar in color and texture to the facial subunit, remains an option.


The goal of craniofacial microsurgery is to reestablish a necessary structural foundation with hard and soft tissue, and the goal of subsequent revision surgery is to refine contour and volume while modifying the “unlike” flap skin with “like” local skin. Integration of the aforementioned concepts is crucial in replacing missing tissue, maximizing craniofacial function, and optimizing aesthetic results.




Indications


The application of microsurgery to craniofacial surgery has been successfully established, largely due to the synthesis of multiple disciplines and their respective collaborations in the treatment of complex disease processes. The indications for microvascular intervention in head and neck surgery are constantly evolving and must not be restricted to a certain measurement of defect, anatomic location, or disease process. Although the reconstructive ladder is dogmatic to the practice of many plastic surgeons, free tissue trans­fer has long been established as a form of “jumping” the “steps” of the ladder. Free tissue transfer to the head and neck is most frequently incorporated following oncologic resection, trauma, infection, osteoradionecrosis, or congenital deformity or malformation, or as a means of reconstructing a failed prior flap. However, indications for free tissue transfer to the craniofacial region must broadly be considered from an anatomic, functional, and aesthetic perspective, all while considering alternative options. Essentially, fixed indications are difficult to define as anatomic, functional, and aesthetic components vary considerably and a single component of the three can skew an evaluation to necessitate microsurgical intervention, rather than using other reconstructive methods.


To simplify the approach to numerous defects of the head and neck, and to facilitate a comprehensive understanding of workhorse flaps that have been developed, refined, and proven to yield successful outcomes throughout the last decade, surgical technique, advantages, disadvantages, pitfalls, and their application are reviewed below. These flaps include the ulnar forearm flap; anterolateral thigh (ALT) flap; latissimus dorsi flap; deep circumflex iliac artery (DCIA) flap; and free fibula flap. Each flap is dynamic and can be altered slightly to incorporate various characteristics necessary for specific craniofacial defects. Their application to a variety of anatomic locations, including the scalp, periorbital region, midface, and mandible, is now described with corresponding cases and figures.




Regions of the Head and Neck


Scalp and Forehead


The forehead is defined by the hairline superiorly and by the eyebrows and frontonasal groove inferiorly. The hairline varies with age, among genders, and ethnicities. The forehead can be further divided into aesthetic subunits: central, paramedian, and lateral. The central subunit is bordered by the medial eyebrows and extends vertically from the glabella to the frontal hairline. The paramedian subunit extends from the lateral border of the central subunit to the lateral eyebrow, or slightly past the convexity of the forehead. Finally, the lateral subunit spans the area lateral to the paramedian subunit until the temporal hairline.


Certain principles can be broadly applied to forehead reconstruction to obtain a successful result:




  • Brow symmetry must be maintained.



  • Hairline symmetry (frontal and temporal) must be maintained.



  • Scars should be concealed within relaxed skin tension lines, borders of aesthetic subunits, or within the hairline.



  • Motor and sensory innervation should be preserved.



Commonly, full-thickness forehead defects will involve the frontal muscle. This can cause significant eyebrow ptosis with subsequent asymmetry and may require botulism toxin injection or secondary revisions. Beyond the forehead lies the scalp, which poses unique challenges.


Scalp reconstruction often involves a hair-bearing region that is unique to patient identity. Hair is both a crutch and a challenge. Contour deformities and scars can be well hidden, but replacing non-glabrous with glabrous skin requires that hair restoration be included in the reconstructive plan.


Free tissue reconstruction of the scalp and forehead is generally reserved for large, full-thickness defects. Current recommendations suggest free flap coverage is indicated for forehead defects >50 cm 2 . Due to the skeletal architecture of this area, as well as the potential need for large skin paddles, the most common flaps in our experience are the fibula flap (when bone is needed); anterolateral thigh flap (when bulk and surface area are needed); and the ulnar flap (when there is a minimal requirement for hair and the wound bed will be spared from radiation treatment). The superficial temporal artery is commonly used for anastomosis due to its predictable location, ease of access, and adequate diameter and length, but other vessels can be used.


Periorbit


The periorbital region is composed of the superior, lateral, and inferior orbit and anteromedial portion of the temporal region. It is known to be the first part of the face that a stranger sees. The periorbital region supports for the orbit and extraocular function. Both are important in establishing a reconstructive goal. Blink depends on functional orbicularis oris and palpebral levator muscles. In addition, blink can be disrupted by ectropion, entropion, exophthalmos, enophthalmos, and eyelid ptosis or retraction. Any of these may be present as a result of the original defect or may occur during reconstruction. Their prevention and repair is a major functional goal in periorbital reconstruction.


Aesthetic outcomes are largely dependent on the underlying skeletal structure of the region. Similarly, attachments of the medial and lateral canthi must be precisely re-created to achieve a symmetric and aesthetic result.


Defects of the orbital rim and skeletal buttresses are best reconstructed with vascularized bone. The fibula free flap is an excellent choice with adequate length and thickness. Although soft tissue alone may be used to camouflage small skeletal defects, the lack of bony attachment for surrounding soft tissue increases the risk of the aforementioned complications. In addition, bone (preferably vascularized) is necessary for bone-anchored prosthetic rehabilitation either immediately or in a delayed fashion.


Soft-tissue requirements differ throughout the periorbital areas and should be matched by thickness, texture, and color. Guided by the critical concepts described above, soft tissue reconstruction should include excess soft tissue with the expectation that volume loss will occur. Volume loss will be even greater if the patient undergoes radiation therapy and must be anticipated. Vascularized fat can be used to provide soft tissue bulk and minimize atrophy. When thin soft tissue is needed with a long pedicle, the ulnar forearm flap is a good choice, with the additional benefit of a favorable donor site and hairless skin. Alter­natively, if bulk and a short pedicle are needed, the groin flap may be used. Alternatively, the anterolateral thigh flap may be used if large amount of skin and soft tissue is required.


Midface


The goals of midface reconstruction are to preserve projection of the midface and to restore the skeletal buttresses. The skeletal buttresses are areas of thick bone that function to transfer forces from mastication to the cranial base. They also absorb any impact to the facial skeleton and protect surrounding fragile structures. There are three paired vertical buttresses: nasomaxillary, zygomaticomaxillary, and pterygomaxillary. Additionally, there is a midline frontoethmoid-vomerine buttress. The function of these vertical buttresses is mainly the transmission of mastication forces to the skull base. The weaker, horizontal buttresses are comprised of the superior and inferior orbital rims and the alveolar ridge. The vertical buttresses, inferior orbital rim, and alveolar ridge fall within the scope of midface reconstruction. Their repair is critical to midface reconstruction. Vascularized bone is the preferred choice when defects of the midface require free tissue transfer (such as a free fibula flap).


In the midface, is it critical to assess which tissue types are missing and to reconstruct them accordingly. Lining is often a missed element of reconstruction, which if not restored can lead fistula formation or contracture. Although the midface is an area that tends to be reconstructed with soft tissue free flaps, bone is necessary to restore the skeletal buttresses and maintain projection of the midface. When bone is required, both the fibula and iliac crest flaps (DCIA flap) are good choices depending on the shape of bone and length of pedicle required. Soft tissue–only flaps may be used for small defects, for which the rectus femoris and ALT can both be used depending on the amount of skin required.


Although multiple classification systems for midface defects exist, their attempts to define the best free flap choice for reconstruction have not been universally accepted. Ultimately, the specific defect and its components must guide reconstruction. The application of the previously described seven head and neck concepts will dictate which elements must be reconstructed as the best flap choice, since optimal reconstruction is not restricted to one type of flap.


Nose


Nasal reconstruction dates back to approximately 3000 bc , and the nascent art of reconstructive surgery evolved from the early work of Samhita, Branca, Carpue, and von Graefe and their contributions to nasal reconstruction. Variations in defect size and aesthetic units will demand specific local flaps (cheek flap), skin grafts, rotation flaps (forehead flap), and potential use of cartilage and mucosal grafts. Coverage of extensive nasal defects can be completed using a prosthetic attachment or using autologous tissue to permanently restore nasal form, nasal respiration, and vocal tone. Although a combination of the aforementioned nasal reconstructive techniques can be successfully used in composite tissue nose defects, the following text focuses on microsurgical reconstruction of the nose.


Historically, replantation of composite nasal tissue defects following traumatic amputation (often a dog bite or a form punishment) have resulted in a high failure rate or led to deforming contracture and nasal passage stenosis. However, the 1990s heralded an era of promise using microsurgical replantation yielding excellent results. The challenge of nasal microsurgical replantation is two-fold.




  • Veins may be difficult to identify within the amputated nose.



  • Once identified, vessel replantation may require supermicrosurgery.



Selecting subcutaneous veins may be advantageous when named veins are difficult to isolate within an amputated segment, but Stillaert et al. showed success with arterial-only anastomosis using adjunct leech therapy in two patients. The success of replantation allowed microsurgical free flaps for nasal reconstruction to gain momentum as a viable option.


Currently, free flap options for nasal reconstruction are ample, likely owing to a lack of one specific flap to distinguish itself as the best option for reconstruction. Typically, selected free flaps have contained the necessary components for reconstructing nasal mucosa, bone, cartilage, and skin. Variations of an ear flap have been popularized including the helical rim, chondrocutaneous ear flap (combined with osteocutaneous femur), and reversed superficial temporal artery (STA) auricle flap. Tailoring the ear flap to a specific aesthetic subunit is ideal, but some defects may be too large, requiring a larger volume of tissue such as the radial forearm flap; prelaminated radial forearm flap; dorsalis pedis flap; composite rib; serratus, latissimus, and skin island flap; and others. The facial vessels are the most common recipient sites of anastomosis, and the absence of the facial vein may necessitate a vein graft. Conscientiously reconstructing the nasal mucosa is critical in avoiding stenosis, and the liberal use of skin grafts or flap folding is recommended in achieving adequate nasal lining.


Mandible


The mandible is one of the few instances where free-tissue transfer has become the standard of care in reconstruction of large defects. The need for dental rehabilitation as well as the high complication rate associated with long-term use of hardware has made vascularized bone an ideal choice for mandibular reconstruction. Defects >5 cm are best reconstructed with free tissue, whereas smaller defects may be reconstructed with bone grafts or hardware in select cases. Vascularized bone, however, enables immediate or delayed dental rehabilitation with osseointegrated dental implants. The fibular free flap has become the workhorse flap due to its shape and long pedicle. The iliac crest (DCIA flap) is frequently another viable option, especially given its similar angular structure to the ipsilateral mandible and the ample bone height it provides for dental implants. Both the FFF and DCIA contain the elements necessary to restore oral mucosal defects, soft tissue, and bony deformities.


Tongue


Tongue defects vary in size and location (tongue base, oral tongue, or both). Small defects involve less than one-quarter of tongue segment, which are amenable to secondary intention healing, primary closure, skin grafts, or local flaps. Prior to the adoption of clinical microsurgery, the traditional tongue reconstruction following total or subtotal glossectomy was pectoralis or trapezius pedicled flaps, primarily to achieve wound closure. With time, free tissue transfer has become the gold standard in reconstructing large or total tongue defects with multiple flaps including the radial forearm flap; ALT flap; infrahyoid myofacial flaps; latissimus dorsi; rectus abdominis muscle flap; gracilis flap; medial gastrocnemius flap; pectoralis flap; parascapular flap; DCIA flap; and fibula flap; all serve as suitable options depending on the details and extent of the defect. The complexity of the tongue includes its innervations and proprioceptive biofeedback, and specialized movements make full functional recovery extremely challenging. The purpose of repairing tongue defects is to reestablish its function to propel a bolus of food toward the pharynx, restore ability to vocalize intelligible speech, prevent aspiration, and optimize aesthetic appearance of the oral cavity and face. Flaps with excess bulk and length facilitate contact between the palate and tongue owing to improved long-term outcomes in deglutition and speech. Large defects that involve >50% of resection, harvesting 20–30% of excess muscle to accommodate for atrophy, de-epithelialization, and folding a flap will preserve tongue height and length. Also, harvesting fascia or chimeric flaps incorporating fascia or excess soft tissue can aid in protecting adjacent defects from fistula formation or excess. If composite defects accompany tongue resection, the fibula flap and DCIA are ideal sites for obtaining bone, muscle, and skin.


When smaller defects are encountered, preservation of remaining tongue tissue is of paramount importance to restoring optimal mobility of the tongue and subsequent free flap. The boundaries of the defect will often spare adjacent structures and preserved tissue of the tongue will retain partial function, at which point a thin and smaller flap is optimal because it is less likely to impede an already functioning tongue. The principles of constructing the neotongue are to accurately reapproximate the biomechanics of the original tongue as this will lead to better cortical adaptation.


Glossectomy has a larger impact on quality of life than other resections of head and neck structures. Contemporary reconstructions attempt sophisticated free flap techniques to preserve motor or sensory innervation to the tongue to maximize function and in turn improve health-related quality of life. Examples of such flaps include the radial forearm flap and the ALT flap, which allow for nerve coaptation of the lingual nerve for sensation and hypoglossal nerve to minimize atrophy and maximize function. The use of functional muscle flaps for tongue reconstruction boasts increased speech intelligibility, better palatal occlusion, and improvement in deglutition. Despite optimal flap selection, the function and mobility of the tongue are dependent on re-creating the form of the tongue. This can be accomplished by re-creating the glossoalveolar and buccoalveolar sulcii, with the option of laryngeal suspension and esophageal widening depending on anatomic flap inset. In the event of a unilateral deficit, a unilateral Z-plasty can tailor a neotip (from the intact tongue to cross toward the flap site) to improve tongue tip function and sensation.


Postoperatively, all patients should be enrolled in speech and swallowing rehabilitation with a skilled pro­fessional to optimize speech intelligibility, swallowing time, and palatal-tongue articulation, and improve their overall quality of life. Patients are at increased risk of deve­l­oping obstructive sleep apnea and should be considered for assessment and treatment following recovery from reconstruction.


Esophagus


Esophageal reconstruction can be accomplished using multiple tissue types as conduits. The most commonly used replacement organ for the esophagus is the stomach, either completely intact or tabularized, depending on the extent of esophageal excision and gastric involvement. Other tissue types such as pedicled muscle flaps, colon interposition (based on the ascending branch of the left colic artery), and pedicled jejunal flaps (often supercharged) have been successfully employed. Reestablishing a conduit for appropriate gastrointestinal continuity for transit of solid and liquid food contents is the primary goal of reconstruction. The rate of conduit stricture following gastric reconstruction is approximately 14%, and colonic interposition grafts are more likely to manifest redundancy and subsequent recurrent luminal collapse in 15–30% of cases. Known disadvantages of the stomach and colonic conduits include insufficient length, tenuous blood supply following gastric surgery, and aberrant colonic vascular anatomy, and grafts are susceptibility to gastric reflux resulting in secondary metaplastic changes. Patients may be better candidates for initial reconstruction with microsurgical free tissue transfer in the event of:




  • Extensive oncological extirpation or other tissue damage (lye ingestion) that involves excision of a lengthy esophageal segment



  • Impaired use of other donor organs such as the stomach



  • The cervical esophagus (in the setting of laryngectomy or glossectomy) is involved



Furthermore, a subset of patients may require a second reconstruction due to complications of the initial reconstruction requiring microsurgical free tissue transfer.


The most commonly used free flap employed in restoring esophageal continuity is the jejunum. The jejunum can be used as a total microsurgical free flap or a supercharged pedicled jejunal flap, which was developed by Longmire in 1946, and is a modification of Carrel’s and Roux’s techniques developed in dogs circa 1906, and humans in 1907, respectively. The advantages of the jejunal free flap include its durability, sufficient quantity, and limited effect on physiologic effect of gastrointestinal function. Furthermore, the diameter of the jejunum best approximates the native esophagus, and peristaltic activity can be preserved. The functional results of jejunal interposition and safety profile demonstrate superior outcomes in swallowing, hospitalization time, and mortality. The span of the esophagus throughout the entire thorax explains the variety of recipient vessels used for anastomoses including internal mammary vessels, superior thyroid artery, transverse cervical, external carotid artery, external jugular vein, internal jugular vein, cephalic vein, or facial vessels. The inset of the flap may require increasing the anterior mediastinal space that can be accomplished with partial manubrial excision, extending the diaphragmatic esophageal hiatus, and tunneling a pliable, soft dilating catheter from the stomach to the mediastinum. In pediatric esophageal replacement, a meta-analysis found that stricture rates were higher in jejunal free flaps compared with colonic and gastric conduits. This may be due to small anatomy and local ischemic effects or a discrepancy in the rate of anatomic growth in the growing infant/child, but to date, there is a lack of consensus regarding optimal conduit selection in all ages.


Voice


The larynx is the second most common site for cancer in the upper aerodigestive tract and commonly requires total laryngectomy, which involves separation of the aerodigestive tract (tracheostoma) and closure of the pharynx or reestablishing a conduit for swallowing. The direct result is a profound alteration in speech or a complete impairment of vocal function that is largely responsible for psychosocial and emotional patient anguish. There are multiple methods of alaryngeal speech including electrolarynx, esophageal speech, and tracheoesophageal (TE) speech, which has become the gold standard in measuring success of speech. Often this requires speech therapy with a specially trained speech pathologist. However, novel modalities of reconstruction have introduced several flaps that attempt to augment the voice. These mechanics of speech mimic the motion of air in TE speech, that is to protract tracheal air passage toward a communication created with the esophagus. This iatrogenic fistula is subject to reflux of esophageal content, secretions, and subject to aspiration and stricture. The technique of puncture and valve placement can be employed in the native esophagus or the neoesophagus. Although prosthetic one-way valves are low-cost, easily reproducible, and attempt to mitigate these risks, there are several surgical methods of voice reconstruction that may obviate their use.


In the setting of simultaneous esophageal and voice reconstruction, the restoration of voice using autologous free tissue transfer is based on the re-creation of the TE tract with mucosa from a neoesophagus. Free jejunum and ileocolon flaps ( Figs 14.2 , 14.3 ) are able to restore voice with excellent long-term patency while simultaneously serving as conduits in esophageal reconstruction. Those patients requiring only voice reconstruction have two microsurgical options. The ileo-ileocecal valve flap ( Fig. 14.4 ), which incorporates a cecal anastomosis to the esophageal wall, preserves the ileocecal valve, and requires an ileal anastomosis to the trachea. Another option is the appendix, which can be used as the TE conduit for communication between the esophagus and trachea. The extent of resection, involvement of esophageal resection, exposure to radiation, prognosis, prior abdominal surgeries, and previously failed voice rehabilitation aid the microsurgeon in selecting optimal patients and optimal approaches to reconstruction.




Figure 14.2


Free jejunal flap for voice reconstruction in the setting of concomitant esophageal reconstruction.



Figure 14.3


Ileocolonic flap for voice reconstruction in the setting of concomitant esophageal reconstruction.



Figure 14.4


Ileal-ileocecal valve for voice reconstruction.




Free Flap Choices for Craniofacial Reconstruction


Ulnar Forearm Flap


The radial forearm flap has become a workhorse flap for head and neck reconstruction given its ease of harvest, long vascular pedicle, and thin, supple skin paddle. The ulnar forearm flap ( Fig. 14.5 ) shares similar traits and offers additional benefits over the radial forearm flap (discussed below). However, concerns about donor site morbidity have prevented the ulnar forearm flap from achieving the popularity of its radial counterpart.




Figure 14.5


Illustration of a raised ulnar flap with anatomy depicted, and depicting a proximally based flap.


Anatomy


Blood supply is based on the ulnar artery and its venae comitantes, but the basilic vein can be utilized for venous outflow. The arterial and venous pedicles are both approximately 2.5 mm in diameter; however, the venous diameter varies depending on whether the vena comitantes or basilic vein is used for anastomosis. The arterial pedicle length can be maximally harvested to the take off of the common interosseus artery (about 15 cm), and will consistently be shorter than the arterial pedicle of the radial artery forearm flap, which can be dissected to the bifurcation of the brachial artery. The maximum skin paddle size measures approximately 15 × 10 cm, similar to the area of the radial forearm skin paddle. Preservation of the medial antebrachial cutaneous nerve will yield a sensate flap, if it is desired for the reconstruction. An osteocutaneous ulnar forearm flap incorporating a portion of ulna bone is possible, but it is not commonly used.


The forearm is supplied by the brachial artery, which divides into the radial and ulnar arteries at the level of the antecubital fossa. However, anatomic variations in the origin of the ulnar artery do exist. Distally, the ulnar artery gives off the anterior and posterior ulnar recurrent arteries, followed by the common interosseous artery. The ulnar artery courses ulnar and deep to the pronator teres, flexor carpi radialis, and flexor digitorum superficialis running along the flexor digitorum profundus. It assumes an ulnar route as it reaches the midpoint of the forearm. Traveling between the flexor digitorum superficialis and flexor carpi ulnaris, it then passes through Guyon’s canal at the wrist and divides into superficial and deep palmar branches. The ulnar artery runs adjacent to the ulnar nerve and often courses deep to the nerve. The ulnar forearm flap drains via a deep or superficial venous system. The deep system is comprised of two venae comitantes accompanying the ulnar artery along its course through the intermuscular septum and drain into the median cubital vein at the level of the elbow. The superficial system consists of the basilic vein and its associated branching veins. The basilic vein drains the dorsum of the hand via the dorsal venous complex of the hand running proximally along the dorsal ulnar aspect of the forearm.


The ulnar nerve is intimately associated with the ulnar artery as it courses over the distal two-thirds of the forearm and is found just ulnar and slightly superficial to the artery. The medial antebrachial cutaneous nerve travels with the basilic vein in the upper arm, exits the deep fascia above the elbow, and divides into anterior and posterior branches. The anterior branch follows the course of the basilic vein distal to the elbow and innervates the medial half of the anterior forearm.


Surgical Technique


Preoperative markings begin with a line drawn from the medial epicondyle of the humerus to the lateral edge of the pisiform bone, estimating the course of the ulnar artery in the forearm. Alternatively, a more accurate method of tracing the ulnar artery is completed with a Doppler probe. The basilic vein is traced using the Doppler probe as well. The flap is designed with its central axis along the course of the ulnar artery in the mid- and distal forearm.


The extremity is then elevated and exsanguinated, and the upper arm tourniquet is applied. Dissection begins at the distal aspect of the free flap. A skin incision is made and dissection proceeds to between the flexor carpi ulnaris and flexor digitorum superficialis tendons to identify the ulnar artery and nerve. The artery is dissected from the nerve and ligated distally. If the basilic vein can be identified, it is ligated at this time. Raising the skin paddle begins in the suprafascial plane, oriented from radial to ulnar direction until the muscular septum, found between the flexor digitorum superficialis and flexor carpi ulnaris is encountered. Once the fascia is identified it is incised, and the ulnar vessels are elevated with the skin flap to preserve septocutaneous perforators. Dissection of the ulnar artery (and the basilic vein) is continued proximally to achieve sufficient pedicle length. Pedicle length is maximized if dissection is carried to the common interosseous artery.


The donor site is best closed over a closed suction drain due to the potential space created by the flap harvest. Primary closure is possible, but skin grafting may be necessary. A full-thickness skin graft will yield superior cosmetic results and provides durable coverage of exposed muscles and tendons. However, a split-thickness skin graft may be used.


Application, Advantages, and Disadvantages


As with the radial forearm flap, the ulnar flap provides a thin, pliable skin paddle with lengthy vascular pedicle of relatively large caliber. The ulnar forearm flap surpasses the radial flap both in cosmetic outcomes of the donor and recipient sites. The ulnar forearm skin is usually less hirsute than the radial skin, allowing the surgeon to circumvent transfer of dense hair-bearing tissue to reconstruct a defect in a non–hair-bearing region. The donor site is also better concealed along the ulnar aspect of the forearm, especially in repose as it sits along the body and out of sight during face-to-face interaction. The donor site is also prone to superior skin graft take because the ulnar region is subjected to less tendon glide and mechanical shear forces as there are more underlying muscle bellies rather than tendons in this region.


Reluctance to utilize the ulnar forearm flap, out of concern for compromising hand perfusion, still pervades the microsurgical community. Additionally, the close relationship of the ulnar artery and nerve has evoked concerns about injury to the nerve during flap elevation. However, multiple studies have failed to demonstrate any significant long-term motor, sensory, or vascular impairments following ulnar forearm flap harvest.


The ulnar forearm flap can be utilized in small, soft tissue midface defects, periorbital contracture or missing tissue ( Fig. 14.6 ), and forehead defects. However, the advantages of the ulnar flap are its similar skin composition of facial components and relative soft tissue paucity that can act as a “double-edged sword,” in scenarios where more soft tissue is necessary. The denervated flap may thin over time, which is why an already minimal volume of soft tissue can thin and may expose underlying hardware.


Mar 3, 2019 | Posted by in Reconstructive surgery | Comments Off on Head and Neck Reconstruction
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