Radiation effects on tissues greatly complicate reconstruction of head and neck defects. We discuss the unfavorable surgical conditions set up by prior surgery and radiation in patients undergoing salvage ablation of recurrent cancer. With the focus on vessel selection, flap donor site characteristics, and management of potential complications, we hope to highlight some of the lessons learned from these complex cases. Special attention is given to the topic of laryngopharyngeal reconstruction.
Key points
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Reconstruction of the head and neck defects in a salvage setting increases the risks of complications.
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Protection of the vascular pedicle from a potential salivary leak is paramount to success of the reconstructive effort.
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Elimination of dead space and selection of suitable donor blood vessels for the anastomosis is important.
Since the introduction of microvascular techniques in head and neck reconstruction, the field has progressed tremendously with free flap survival rates ranging from 90% to 98%. Many factors contribute to this degree of progress. Experience of the surgeons, improved understanding of the physiologic changes associated with ischemic injury and reperfusion, preoperative patient selection, and vigilant postoperative care are essential to safely accomplish the goal of a successful reconstruction.
However, the challenges to microvascular reconstruction have increased significantly as primary radiation for head and neck malignancy has become more widely used. Salvage operations after failure of primary radiation or of multimodality treatment are common indications for free flap reconstruction. Bone containing free tissue transfer is the most reliable strategy in treatment of Grade III osteoradionecrosis (ORN). The changing trends in the indications for free flap reconstruction were highlighted in the review of the University of California Los Angeles experience. The proportion of ORN cases increased from 1.3% of all patients undergoing maxillomandibular reconstruction from 1995 to 2000 to 8.7% from 2001 to 2006 to 17.5% from 2007 to 2012 ( P <.05). Thus, a surgeon who may expect a favorable outcome in a reconstruction performed in the primary setting must be prepared for, and anticipate, the obstacles that arise in the reconstruction of an ablative defect in an irradiated field performed in the salvage setting.
Here we review the lessons learned, and the key considerations for optimizing results when performing reconstruction in a patient with a previous history of head and neck radiation.
Radiation effects
Radiation effects on the tissue are well known to most clinicians treating patients with head and neck malignancies. Although early radiation-induced skin and mucosal reactions acutely affect patients during and immediately after radiation treatment, it is the delayed radiation injury that will affect long-term healing. These changes develop 4 to 6 months after completion of therapy. Epidermal atrophy and vascular and connective tissue changes leading to the loss of elasticity and fibrosis significantly reduce the pliability of soft tissues. With denser collagen fibrils and irregular elastic fibers, the tissue planes of the neck are often scarred. Lymphatic drainage is compromised with increases in postoperative edema. Vascularity is impaired with thrombosis and obliteration of capillaries, resulting in poor tissue perfusion and oxygenation. Arterioles and small arteries demonstrate progressive vascular sclerosis and narrowing. Periosteal blood supply to bone is compromised, placing the mandible at risk for ORN. Not only is wound healing impaired, but there is also a reduced capacity for local immunologic response, which increases the risk of infection and wound complications.
Radiation effects
Radiation effects on the tissue are well known to most clinicians treating patients with head and neck malignancies. Although early radiation-induced skin and mucosal reactions acutely affect patients during and immediately after radiation treatment, it is the delayed radiation injury that will affect long-term healing. These changes develop 4 to 6 months after completion of therapy. Epidermal atrophy and vascular and connective tissue changes leading to the loss of elasticity and fibrosis significantly reduce the pliability of soft tissues. With denser collagen fibrils and irregular elastic fibers, the tissue planes of the neck are often scarred. Lymphatic drainage is compromised with increases in postoperative edema. Vascularity is impaired with thrombosis and obliteration of capillaries, resulting in poor tissue perfusion and oxygenation. Arterioles and small arteries demonstrate progressive vascular sclerosis and narrowing. Periosteal blood supply to bone is compromised, placing the mandible at risk for ORN. Not only is wound healing impaired, but there is also a reduced capacity for local immunologic response, which increases the risk of infection and wound complications.
Surgical salvage
Despite the progress in the oncologic management of head and neck malignancy, rates of persistent or recurrent disease of 40% to 50% have been cited in the literature for patients with advanced-stage tumors. Salvage surgery is, by definition, the last resort at clearing local and regional disease. Although 20% to 30% of patients with local and regional failure are candidates for surgical salvage, achieving cure remains difficult. Detection of tumor margin in an irradiated field is challenging on preoperative imaging, intraoperative inspection, and on histopathologic analysis. In an irradiated field, fascial barriers are less likely to stop aggressive recurrent tumor spread, and a wider resection often must be performed than in a primary setting. As an example, after radiation exposure, the periosteum of the mandible provides less resistance to tumor invasion of the bone. Rather than infiltration through an occlusal surface alone, in an irradiated specimen, invasion is seen at multiple sites along the cortex. The reduced structural support of the irradiated bone, and the higher likelihood of cortex invasion from the adjacent mucosal sites often renders marginal mandibulectomy an unfavorable option in a salvage setting. For these patients, composite resection with a resultant segmental defect is the preferred option. Similarly, recurrence or persistence in the neck may present with extensive extracapsular extension requiring sternocleidomastoid sacrifice with potential carotid artery and jugular vein exposure. The reconstructive team should anticipate and be prepared to address these extensive defects.
A systematic review of the literature suggests that there are similar rates of complications and free flap survival regardless of whether the patient had preoperative radiation therapy. Achieving a similar degree of success in the salvage and the primary settings requires careful planning and anticipation of potential complications.
The authors follow a number of guiding principles to help avoid negative outcomes in this patient population. Here we cover considerations at the time of reconstruction, vessel and flap selection, elimination of dead space, management of wound complications, define what should be designated as a safe wound, and discuss anticipatory strategies for managing flap failure. To achieve success, it is imperative that the surgical team plan every aspect of the surgical procedure and include the potential options for surgical salvage in the event of a complication.
Timing of reconstruction
When it comes to salvage of persistent or recurrent malignancy, the aggressive tumor biology dictates the scheduling of the extirpative procedure. On the other hand, the reconstructive effort may be delayed for a variety of reasons. Negative margins must be ensured, especially when adjuvant therapy options have been exhausted. The surgeon may elect to wait for the final pathology evaluation and stage the reconstruction until a later date. The benefits of this approach versus the morbidity of a separate anesthetic and temporarily open defect must be discussed in detail with the patient. In cases in which there is a high probability of recurrence, and in which visual surveillance becomes limited by the reconstruction, the delay may be extended for a considerable period of time. This approach has been advocated by some investigators for malignancies in the palatomaxillary region.
Active infection has a high potential for compromising the microvascular reconstruction. This adverse environment can be seen in cases of osteomyelitis, a pathologic fracture resulting from advanced ORN of the mandible, or revision of previously failed reconstruction in which necrotic tissue must first be debrided. In these types of situations, delayed free tissue transfer, treating the patient with antibiotics, and local wound care may optimize the recipient site for successful free tissue transfer as a staged procedure.
More often than not, however, the reconstruction has to be performed without delay to avoid extensive morbidity, additional scarring, and to optimize the functional outcome with the most rapid restoration of the quality of life.
Vessel selection
Exposure to radiation can induce arteritis and fibrosis of the surrounding tissue bed. Radiation for malignancies of the oral cavity and oropharynx can result in significant damage to the branches of the external carotid artery. In addition, blood vessels may be absent as a result of prior neck dissection, leaving the reconstructive surgeon with limited options in a vessel-depleted neck. As mentioned previously, the key to success in a salvage effort is anticipation of potential complications. A leak resulting from poor healing of the intraoral suture lines places any anastomosis located in the upper neck at risk. Exposure to saliva and infection can be minimized by placing the anastomosis in a more remote location, away from a potential drainage pathway from the oral cavity. This can be successfully accomplished by using the transverse cervical artery (TCA). Not only is this vessel outside of the radiation field in most patients, it can also be found in a previously undissected region of the lower neck. Distal dissection, deep to the trapezius muscle, followed by transposition of the TCA can provide favorable vessel geometry with a vertical orientation of the pedicle in the neck. In elderly patients, the TCA is less prone to significant atherosclerotic disease. Another novel option for the arterial supply to the flap in a vessel-depleted neck is the internal mammary artery. The inferior thyroid artery also should be considered as a potential candidate.
Recipient veins for flap drainage also may prove to be scarce in the cervical region in a salvage, postradiation setting. The transverse cervical vein can be used along with the TCA, although it is often of small caliber. Internal mammary veins become a good option when the artery is harvested in the intercostal space ( Fig. 1 ). In addition, the cephalic vein can be followed in the deltopectoral groove toward the upper arm and transposed into the neck. This maneuver brings a good caliber vein into the neck, avoiding the need for a vein graft. Vessel selection is done on a case-by-case basis, and the surgeon should be prepared to use the options listed previously, extend the anastomosis to the contralateral neck, and use arterial and venous grafts when appropriate. The key to avoiding complications at this step of the reconstruction is to optimize the recipient artery and vein, rather than to compromise on a potentially unreliable vessel so as to avoid further dissection. It is also important for the reconstructive surgeon to have a series of alternative options for recipient vessels, should they be needed in the primary or secondary settings.
Flap selection
A large number of donor sites are in the armamentarium of the modern reconstructive surgeon. Matching the particular demands of the defect with the appropriate donor tissue(s) is of utmost importance. In a salvage setting, additional considerations should influence flap selection. In our experience, vascularized muscle provides added protection against infection. This principle is well described in the vascular surgery literature in which healthy muscle is often used to increase local tissue oxygen tension, augment the delivery of immune cells and antibiotics, and eliminate dead space. Although vascularized fat may achieve the goal of replacing lost volume, muscle is invaluable for vascular protection in the case of a salivary fistula. When scapular bone is used to reconstruct the mandible following a composite resection of the oral cavity and/or oropharynx, the latissimus dorsi muscle, perfused by the thoracodorsal branch of the subscapular artery, can be harvested and used for coverage of the carotid artery, the jugular vein, and the microvascular pedicle. Anchored superiorly to the reconstructed segment of the mandible, a potential salivary leak is directed superficial to the muscle, effectively protecting the vessels beneath. The authors prefer to use the subscapular system chimeric flap, rather than a fibular free flap, in salvage reconstruction of a composite oral cavity/oropharynx defect ( Fig. 2 ). When vascularized muscle is not incorporated in the composite flap and brought into the defect as part of the free tissue transfer, we routinely cover the vessels of the neck with a pectoralis major rotational flap. The muscle helps to avoid vessel exposure in case of neck wound break down. This is especially important when the skin cannot be closed without tension, as is often the case with the loss of elasticity associated with radiation exposure. The excess bulk of the muscle can be left exposed, and epithelialization occurs in a matter of weeks. In our experience, acceptable cosmetic results can be expected without the use of skin grafts. Muscle atrophy restores the neck contour to near normal within several months. In chimeric flaps, where all components are supplied by the common vascular pedicle, the exposed muscle can serve an additional role of a flap monitor.
