SKIN AND SOFT TISSUE
CHAPTER 17 RADIATION AND RADIATION INJURIES
JAMES KNOETGEN III AND SALVATORE C. LETTIERI
Roentgen’s discovery of X-rays in 1895 was closely followed by the introduction of radiation therapy for the treatment of a variety of cancers and other disease processes. Radiation provides both diagnostic and therapeutic benefits, but the resulting changes to exposed tissues pose wound healing problems and reconstructive dilemmas for which the plastic surgeon is often consulted. This chapter explains the basics of radiation therapy, discusses the radiation wound issues that are frequently faced by plastic surgeons, and emphasizes the unique problems posed by specific anatomic locations.
Radiation refers to the high-energy particles (alpha particles, beta particles, and neutrons) and electromagnetic waves (X-rays and gamma rays) that are emitted by radioactive substances (uranium, radon, etc.). Alpha particles are large, positively charged, helium nuclei. Radium and radioactive isotopes can be consumed orally or intravenously to emit alpha particles into surrounding tissues. Beta particles are small, negatively charged electrons and are used in electron beam therapy (e.g., treatment of mycosis fungoides), and can penetrate up to 1 cm of tissue. Gamma rays are uncharged photons produced by the natural decay of radioactive materials (radium, cobalt 60, etc.) and can penetrate deeply into tissues. Roentgen rays (X-rays) are similar to gamma rays, except that they are artificially emitted from tungsten when bombarded with electrons.
Radiation doses are measured in a variety of units. These units measure the energy absorbed from a radiation source per unit mass of tissue. The current unit of measure for therapeutic radiation is the Gray (Gy). The Gray is defined as the absorption of 1 J of ionizing radiation by 1 kg of tissue. The older term for this is the “rad,” and 1 rad is equal to 0.01 Gy. A typical curative treatment could be in the range of 60 to 80 Gy. Generally, adjuvant treatments tend to be within the 40 to 60 Gy range. The type of tumor, area of treatment, and goal of treatment determine the precise dosing. The total treatment is usually divided (fractionated) over the course of several sessions. This generally allows the normal, or non-diseased, tissue that surrounds the tumor, to recover better than if it were treated with one large dose.
The two main forms of radiation exposure are irradiation and contamination. Irradiation refers to radiation waves that pass directly through the human body, whereas contamination is contact with and retention of radioactive material. Contamination is usually the result of an industrial accident. The plastic surgeon is most concerned with irradiation as opposed to contamination since current regulations have made industrial accidents and exposures quite rare.
Irradiation is a local therapy applied to a specific body site containing a tumor or disease process, or to draining lymph node beds thought to contain or potentially contain microscopic or gross disease. Large tumors may be treated preoperatively with radiation therapy (induction therapy) to decrease the tumor burden prior to surgical extirpation. Adjuvant radiation therapy is performed in addition to the surgical extirpation with the goal of treating the tumor’s resection bed and regional lymph nodes in specific clinical scenarios, such as large tumors, recurrent tumors, extracapsular lymph node involvement, and positive resection margins. The potential advantage of radiation therapy over surgery is local treatment of disease with preservation of surrounding uninvolved structures. Disadvantages include the length of treatment, the need for access to appropriate facilities and equipment, and the potential additive and chronic effects of radiation therapy.
DELIVERY OF RADIATION
There is a distinction between diagnostic and therapeutic radiation. The most common application of diagnostic radiation is a simple radiograph (X-ray). The amount of radiation delivered for a standard radiograph typically ranges from 20 to 150 kV, whereas a therapeutic treatment range is typically from 200 kV to 25 MV. Radiation therapy can be delivered via external or internal routes. The delivery technique most commonly used is external beam radiotherapy, which originates from a source external to the patient, a linear accelerator (LINAC). A variety of radiation beams can be delivered in this manner, such as low-energy radiation beams from a cobalt source in a cobalt machine. Other atomic particles, such as neutrons, are also delivered via this mechanism. This technique allows daily fractionated delivery of radiation over a several week course. External beam therapy can be delivered as an independent treatment preoperatively, intraoperatively, or postoperatively.
Delivery of radiation from within the patient’s body is termed brachytherapy. Radioactive sources are inserted into the patient for temporary or permanent irradiation. This technique allows for continual treatment of the tumor with radiation over a course that usually lasts several days. Its advantages include decreased treatment time and greater ability to spare uninvolved local tissues. Brachytherapy may also be indicated in patients who have been previously irradiated and are no longer candidates for external beam therapy having already received the maximum recommended dose for a specific anatomic area. Brachytherapy is commonly used for the treatment of pelvic cancers such as cervix or prostate, and this can also be used as an adjunctive therapy for soft tissue tumors. For example, a patient may undergo external beam radiation for the treatment of a sarcoma with subsequent resection and placement of brachytherapy catheters for localized, direct radiation treatments. Plastic surgeons may be consulted because brachytherapy catheters can be covered with a soft tissue flap where primary closure is not possible. The catheters are then “loaded” with various radioisotopes. The “loaded” catheters then create a controlled, localized irradiation until the catheters are removed.
Radiation may also be delivered via robotic methods allowing for the controlled delivery of low dosages of radiation to specific anatomic locations. This technique is used for intracranial tumors, for example.
Regardless of the delivery technique, radiation therapy works by damaging the targeted cells through complicated intracellular processes whose mechanisms continue to be studied to this day. The interaction of radiation with water molecules within the cell creates free radicals that cause direct cellular damage. A range of biochemical lesions occur within DNA following exposure to radiation, and this can result in two different modes of cell death: mitotic (clonogenic) cell death and apoptosis. The biochemical lesion most often associated with cell death is a double-stranded break of nuclear DNA.2
Irradiated tissues suffer both early and late effects. Early effects occur during the first few weeks following therapy and are usually self-limited. They result from damage to rapidly proliferating tissues, such as the mucosa and skin. Erythema and skin hyperpigmentation are the most common problems and these are treated expectantly with moisturizers, local wound care, and observation. Dry desquamation occurs after low to moderate doses of radiation, while higher doses result in moist desquamation. At the tissue level, stasis and occlusion of small vessels occur, with a resulting decrease in wound tensile strength. Fibroblast proliferation is inhibited and may result in permanent damage to fibroblasts. This creates irreversible injury to the skin which may be progressive. While the plastic surgeon is often not required to treat early radiation injuries, chronic injuries frequently require the plastic surgeon’s attention.
Late, or chronic, radiation effects can manifest anytime after therapy, from weeks to years to decades after treatment. While acute effects are uncomfortable and bothersome to the patient, they are generally self-limited and resolve with minimal treatment and local wound care. Chronic effects, however, can be progressive, disabling, cumulative, permanent, and even life threatening. Late injuries include but are not limited to tissue fibrosis, telangiectasias, delayed wound healing, lymphedema (as the result of cutaneous lymphatic obstruction), ulceration, infection, alopecia, malignant transformation, mammary hypoplasia, xerostomia, osteoradionecrosis, and endarteritis. Long-term effects of radiation therapy also include constrictive microangiopathic changes to small- and medium-sized vessels,3 which are significant when performing reconstructive procedures with either pedicled flaps or free tissue transfers.
GENERAL PRINCIPLES OF TREATING IRRADIATED WOUNDS
In most circumstances, a radiated wound will not heal as well as a nonirradiated wound. The plastic surgeon will generally be called upon to care for three different populations of irradiated patients. The first population is those who have not yet received irradiation but will be receiving radiation therapy intraoperatively or postoperatively. This is often seen in the immediate breast reconstruction patient who is undergoing mastectomy and potential postoperative radiation therapy or the sarcoma patient undergoing extirpation with intraoperative radiation therapy. Also, bronchial stumps can be reinforced when a completion pneumonectomy is anticipated, usually with intrathoracic transposition of a serratus muscle flap.4
The second patient population includes those who have already received radiation therapy and now have a recurrent or new tumor, or a radiated wound not amenable to primary closure, frequently with the exposure of vital or significant structures such as the bone, viscera, and neurovascular bundles. These patients will require tumor extirpation or wound debridement(s) followed by reconstruction.
The third group of patients includes those who require reconstruction for intraoperative radiation therapy. Intraoperative radiation therapy is occasionally used in the treatment of sarcomas, pelvic tumors, and other malignancies. In this situation, the reconstructive ladder is applicable and if reasonably healthy soft tissue is present, a primary layered closure can be attempted. Many of these wounds will heal well even though they have received intraoperative radiation therapy. However, if the bone, prosthetic material, or neurovascular bundles are exposed or if a significantly sized soft tissue defect is present, flap coverage is indicated to protect these structures and fill the defect. A subset of this patient category includes those who are receiving brachytherapy catheters intraoperatively, which require coverage.
When confronted with a wound that has late radiation changes, the first step is to rule out the presence of a recurrent or new tumor (possibly radiation induced). It is imperative that the plastic surgeon does not assume this has been ruled out by the referring physician or surgeon. Diagnosis is often assisted by standard radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI) and is confirmed with a tissue biopsy. If tumor is present, a full workup and evaluation by the appropriate extirpative surgeon are required. After tumor extirpation is complete, reconstructive efforts of the resulting defect are then initiated.
If tumor is not present, the next step in management is complete resection and debridement of all nonviable irradiated tissues and foreign bodies (sternal wires, previous sutures, etc.).5 Primary closure or skin grafting of the irradiated wound will fail because of the poor vascularity and fibrosis of the wound bed. Likewise, muscle flaps transposed into an irradiated, poorly vascularized wound bed may not heal well. It is imperative that the plastic surgeon first establishes a clean wound with well-vascularized edges before proceeding with reconstruction. This frequently requires multiple debridements rather than a single operative endeavor, as the extent of radiation injury often exceeds what appears to be the boundary of damaged tissue. A common cause of recurrent infections, sinus tracts, and non-healing wounds is retention of nonviable materials such as foreign bodies, bone, and cartilage secondary to inadequate debridement.
When incising severely irradiated tissue, a defect much larger than anticipated is often created. Irradiated tissue is often tight and creates a constricted skin envelope. When incised, the wound edges will retract and create a larger defect than expected (Figure 17.1). This is an important concept to understand when planning the reconstruction, as one may need more nonirradiated tissue for reconstruction than originally estimated.
Once debridement is complete, stable wound closure is obtained. Thorough preoperative planning and a systematic approach to reconstruction of irradiated defects are needed. Reconstruction usually includes transposition of a well- vascularized nonirradiated soft tissue flap. Reconstruction of these defects is often challenging and is associated with relatively high complication rates. While planning the reconstruction, the plastic surgeon chooses the flap that will best provide a healed wound and maximize preservation of function. It is generally accepted that irradiated muscles should not be transferred as this may result in partial or complete muscle necrosis.6 The transfer of a muscle whose pedicle has been irradiated may also be associated with a higher than normal complication rate.7 If a nonirradiated muscle flap or the greater omentum is not available, a free tissue transfer will be required. Since the tissue surrounding an irradiated wound is fibrotic with endothelial damage in the local vessels, the plastic surgeon must frequently ride the “reconstructive elevator” (rather than the ladder) and proceed directly with a free tissue transfer.
An important concept is that the poorly vascularized peripheral tissue surrounding the open wound requires reconstruction in addition to the wound itself. It is equally important to evaluate the tissue surrounding the defect. The flap must be approximated with well-vascularized tissue rather than irradiated, fibrotic tissue. The redundant flap may also be buried beneath the surrounding injured skin, reconstructing the missing or fibrotic subcutaneous tissue layer. This delivers additional blood supply to the skin and increases “mobility” as well. Flap coverage may also provide some pain relief for these patients. The remainder of this chapter addresses the pertinent issues of irradiated wound treatment by anatomic area.
Non-melanoma skin malignancies can be treated with approximately a 90% cure rate with irradiation (Chapter 14). Since surgical extirpation and radiation treatment provide similar results for skin cancers, the pros and cons of each are considered before a recommendation is made. Surgical extirpation has an immediate result, whereas radiation therapy requires prolonged therapy as well as access to radiation therapy facilities. Long-term complications such as fibrosis, ulceration, ectropion, osteitis, and chondritis are possible complications of radiation therapy. It is therefore generally reserved for patients who are not surgical candidates. There is another subgroup of patients, such as those with positive cutaneous margins or perineural invasion, who may require treatment with postoperative radiation.
FIGURE 17.1. A 60-year-old man with laryngeal cancer treated with radiation resulting in an anterior neck wound. A. Pre-op appearance. B. Treated with resection of all radiated tissues with completion laryngectomy and partial esophagectomy. C–E. Reconstruction with free anterolateral thigh flap. The de-epithelialized central portion of the flap was folded for internal esophageal reconstruction, and skin paddles provided external skin coverage.
Low-dose radiation therapy is also used postoperatively in the treatment of benign disease, such as keloids and hypertrophic scars. This technique takes advantage of fibroblast inhibition caused by ionizing radiation. The radiation is generally administered on the same day the keloid is excised and for several days thereafter.
Soft tissue sarcomas of the extremities can be aggressive tumors involving multiple structures and tissue planes. Surgical extirpation is often combined with intraoperative or postoperative radiation therapy, either external beam or brachytherapy. Therefore, treatment of these patients requires a multidisciplinary approach often involving surgical oncologists, vascular surgeons, orthopedic surgeons, radiation oncologists, plastic surgeons, and others (Chapter 94). The goal is to obtain loco-regional tumor control while simultaneously attempting limb salvage and maximal preservation of limb function. Patients may have received irradiation before extirpation, which is important in the planning of the radiation therapy (i.e., the patient may require brachytherapy as opposed to external beam therapy or a modification of the external beam dose). The sequence is especially important to the plastic surgeon and the planning of wound closure and reconstruction.
Wide local tumor resections of the extremity often result in large soft tissue defects, as well as osseous defects. Osseous defects will require orthopedic reconstruction with prosthetic materials, total arthroplasties, or bone grafts. All bone, tendons, prosthetic materials, and neurovascular bundles must be covered with well-vascularized viable tissue in order to obtain stable soft tissue reconstruction and a healed wound. The addition of radiation therapy to the tumor bed after reconstruction, as well as all previous irradiation, must be considered when planning reconstruction.
The goal of soft tissue reconstruction is to obtain stable coverage of all vital structures. While the “reconstructive ladder” generally proceeds from the simplest to the most complex method of closure, it may be prudent to bypass one or more of the standard rungs to arrive at a more stable closure. For example, a defect in the medial thigh created by resection of a liposarcoma and irradiation that may seem amenable to primary closure may benefit from coverage with a pedicled musculocutaneous flap, especially if the femoral vessels are exposed. Likewise, a soft tissue defect of the knee may not be amenable to coverage with a gastrocnemius muscle flap if this muscle was within the field of previous irradiation and may be better treated with a free muscle flap.
Closure of a defect is not the only goal when reconstructing these wounds. Preserving and maintaining maximal function is of importance as well. When critical muscles or large muscle masses are resected and/or irradiated, it is often advantageous to perform a neurotized muscle reconstruction. This can often give patients at least partial function of a joint or limb.
The breast is an anatomic structure that is frequently irradiated and cared for by the plastic surgeon. Breast reconstructions using autologous or prosthetic materials are more complicated when the treatment plan includes radiation therapy. There are basically two breast patient populations the plastic surgeon will encounter: 1) the patient who has already received radiation therapy to the breast(s) for the treatment of a previous malignancy and is now in need of further extirpation and/or reconstruction and 2) the patient who is undergoing mastectomy and may receive postoperative radiation therapy, usually because of tumor size or nodal involvement.
The first clinical scenario requires the plastic surgeon to perform a breast reconstruction in an irradiated field. The surgeon must first evaluate the breasts and chest and assess the degree of radiation damage. The patient should be examined for erythema, hyperpigmentation, and the degree of fibrosis of the breast and surrounding tissues and skin. A basic tenet of reconstructing the irradiated breast is that delivery of well- vascularized tissue via autogenous reconstruction will yield a far superior result than prosthetic implants alone. Reconstruction with tissue expansion and implants has been demonstrated to yield a higher rate of wound healing problems and implant exposure, as well as a higher incidence of Baker III and IV capsular contracture.8,9 Nava et al. recently reported 257 consecutive patients reconstructed with temporary breast tissue expanders followed by permanent prosthesis. Forty percent of patients who received radiation during the tissue expansion phase had an unsuccessful reconstruction, whereas only 6.4% of those who received radiation therapy to their permanent implants had an unsuccessful reconstruction (vs. 2.3% in the control group)10 (Chapter 59).
Reconstruction with autogenous tissue, usually via a pedicled or free Transverse Rectus Abdominis Myocutaneous (TRAM) flap or a latissimus dorsi muscle flap with an expander/implant, will often yield a superior result. If autologous breast reconstruction is not an option, some surgeons advocate immediate insertion of a breast tissue expander/implant at the time of mastectomy with completion of expansion prior to irradiation,11 although this is a controversial opinion and not widely accepted. An alternative technique employs placement of a tissue expander at the time of mastectomy and before radiation therapy to create and maintain a soft tissue envelope for a later reconstruction that includes autologous tissue, with or without an implant.
A critical issue that requires consideration when performing autologous breast reconstruction is the quality of irradiated vessels of pedicled flaps (internal mammary vessels in TRAM flaps and the thoracodorsal vessels in latissimus dorsi muscle flaps) and the quality of irradiated recipient vessels in autologous reconstruction with free flaps (TRAM, Deep Inferior Epigastric Artery Perforator Flap (DIEP), Superior Gluteal Artery Perforator Flap (SGAP), etc.). Pedicled TRAM flaps have been demonstrated to have a higher incidence of both skin and flap necrosis when the pedicle has been exposed to radiation preoperatively,7 and are associated with an increased incidence of total TRAM flap failure.12 When performing a pedicled TRAM flap with irradiated vessels, decreased complications in this group may be achieved with a flap delay, a bipedicled TRAM flap, or turbocharging the flap (although turbocharging pedicled flaps is a controversial subject).
The alternative is a free tissue reconstruction using a flap that has not been irradiated (Chapter 62). When performing a free tissue transfer for breast reconstruction, the surgeon must inspect the quality of the irradiated recipient vessels. Significant scarring and fibrosis surrounding the vessels and radiation damage to the lumen of the recipient vessels will increase the chance of free flap failure. Radiation therapy results in constrictive microangiopathic changes to small- and medium-sized vessels as well as inhibition of fibroblast function, which increases the risk of anastomotic failure.3
Occasionally, the potential need for postoperative irradiation is uncertain at the time of mastectomy. In this setting, the plastic surgeon must decide whether to perform immediate reconstruction or delay reconstruction until after the potential radiation therapy is completed. This is a frequent clinical scenario faced by plastic surgeons. Most plastic surgeons agree that superior outcomes are achieved with a delayed autologous reconstruction, rather than an immediate reconstruction and postoperative radiation of the flap.13,14 It is therefore prudent to delay reconstruction until the final decision about postoperative irradiation is made.
Head and Neck
Head and neck malignancies provide unique and complicated treatment challenges. These tumors are frequently aggressive with high recurrence rates. Treatment usually requires surgical extirpation and radiation therapy. Surgical extirpation often results in large defects with exposure of vital structures that require complicated soft tissue and/or osseous reconstruction. Extirpation may result in full thickness defects that involve a fistulous communication between the oral cavity and the blood vessels of the neck. Reconstruction of these defects is challenging and is made more difficult if the irradiated tissues are fibrotic and if the local vessels are damaged.
Osteoradionecrosis of the mandible or maxilla is a complication occasionally seen after radiation therapy and is another clinical scenario that requires resection/debridement of affected tissue followed by osseous reconstruction.
The affected regions may be categorized into thirds. The lower third includes the mandible and neck region. The middle third includes the maxilla and the orbit, and the upper third corresponds to the skull base and cranium. Each region is unique and has its own issues and challenges.
The patient with a head and neck malignancy may present in one of several different scenarios. The patient may present without any preoperative radiation and be treated with surgical resection and reconstruction followed by postoperative radiation. Alternatively, the patient may have had preoperative radiation and be scheduled to undergo extirpation and reconstruction. Other possible presentations include patients who have failed radiation therapy with persistent cancer or a recurrent cancer. These patients may require a “salvage” procedure with reconstruction. Finally, there are patients who have undergone successful radiation therapy for malignancy and are “cured” but then suffer from the functional sequelae of the radiation therapy.
While head and neck defects were traditionally reconstructed with local and regional flaps, free tissue transfer has become the standard reconstruction technique. The pectoralis major muscle flap was used for soft tissue coverage of neck defects before free tissue transfer was introduced. This flap is limited by its bulk, difficult arc of rotation, and limited reach into the oral region. Other local muscle flaps such as the sternocleidomastoid or platysma may not be useable or predictable in the irradiated neck. Free tissue transfer allows well-vascularized, nonradiated tissues from a distant site to be used for reconstruction of the radiated defect.
Because of the vital structures located in the head and neck region, it is imperative to obtain a stable closure. Success is measured not only by the cure or control of the tumor but also by wound healing and preservation of function. The primary goals are complete healing without infection, dehiscence, or intraoral breakdown that may result in fistula formation. The secondary goal is maintenance/restoration of function. The tertiary goal is a cosmetically acceptable appearance.
Full thickness defects of the head and neck region may require reconstruction of multiple layers, including the intraoral lining, osseous reconstruction of the mandible or maxilla, esophageal or laryngeal reconstruction, and soft tissue/skin coverage (Figure 17.1). Partial thickness defects may only require intraoral lining or soft tissue coverage. Usually, local flaps are not useable, except for perhaps a temporalis muscle flap to obliterate the maxillary sinus or the palate region. Free tissue transfer is preferred, especially in irradiated head and neck defects. The types of free tissue transfers utilized include a thin fasciocutaneous flap (radial forearm flap), an intermediate thickness flap (scapula or parascapular flap), or a variable thickness flap (anterolateral thigh flap). Muscle flaps (rectus abdominis or latissimus dorsi) can also be used. The greater omentum is excellent as a “carrier” for bone and skin grafts but offers no structural strength.
Generally, vessels in the neck are readily available and of adequate caliber. However, even if the vessel caliber is adequate, irradiated vessels are more difficult to dissect and use for microanastomosis because of local fibrosis and radiation injury to the vessels. Preoperative evaluation of the vessels is recommended. Venous outflow is difficult to assess preoperatively and the possibility that adequate venous outflow will not be found intraoperatively is anticipated. Thoughtful preoperative planning with a “plan A” and at least one “plan B” is necessary before undertaking these procedures. If the radiated vessels are deemed unsatisfactory for anastomosis, the surgeon should be prepared to find vessels in other areas of the neck, such as the contralateral side and the supraclavicular region, or even outside of the neck region. If distant vessels are utilized, then vein grafts are required, so it is imperative to warn patients preoperatively about the potential need for surgery to other parts of their body.Although vein grafting generally increases microanastomotic failure rates, vein grafting into an area that is easily dissected with a technically easier anastomosis is better than a difficult anastomosis to poor quality vessels without a vein graft.
Vein grafts are often necessary for coverage of irradiated scalp defects. Many surgeons prefer to utilize the larger arteries and veins in the neck in lieu of smaller vessels near the scalp, such as the superficial temporal arteries. While several authors have reported success with the superficial temporal artery, it is generally accepted that the neck vessels are easier to work with and have less chance of causing anastomotic problems.
The timing of reconstruction relative to the delivery of radiation also needs to be considered. Induction radiation therapy, used to downstage (shrink) tumors preoperatively, tends to create more bleeding and inflammation in the treated area. Although the irradiated vessels may be adequate for use, the dissection may be tedious because of the inflammation. Chronic radiation injury, however, will tend to have more fibrosis in the affected area as well as thickening of the tissue planes and absence of standard anatomic landmarks, which makes dissection even more slow and difficult.
Patients who will be having postoperative irradiation do not have these issues and will have unoperated tissues and virgin surgical planes. In fact, the neck dissection leaves the vessels exposed and ready for use. It is often prudent to recommend to the extirpative surgeon that an adequate length be left on vessels that are ligated and resected, in order to have a stump for anastomosis, rather than ligating the branch flush with the larger vessel from which it arises.
Osseous reconstructions of the head and neck offer additional challenges. Mandible resections are usually reconstructed with a fibula flap to deliver well-vascularized nonirradiated tissue to the wound bed (Chapter 37). A nonvascularized bone graft will not fare well if the surrounding soft tissue envelope has been irradiated. This may lead to a chronic non-healing wound with possible draining sinus tracts. Generally, a complex full thickness defect that involves bone and intraoral lining is best served by a vascularized bone flap. In the absence of any viable alternatives for vascularized bone graft, a free tissue transfer with a nonvascularized bone graft could then be used. This is not an ideal option considering the possibility of adjunctive radiation that is often administered postoperatively. While some authors have reported successes with bone grafting or a cancellous “tray,” these reconstructions need to be performed within a well-vascularized bed and are therefore not indicated in irradiated wounds.
An uncommon yet potentially lethal complication of radiation therapy to the head and neck is infection leading to wound dehiscence and exposure of the vessels. This can result in vessel rupture or anastomotic leak that can result in life-threatening hemorrhage.
Middle third defects often require maxillary reconstruction. There are few local tissue options and therefore these often require primary vascularized bone graft reconstructions (Chapter 39). The midface area generally has a high risk of exposure to the oronasal cavity and therefore will benefit from reconstruction with vascularized bone grafts.
Reconstructions of the upper third of the head and neck offer unique challenges. The skull base must be separated from the oronasal cavity to prevent infection and cerebrospinal fluid leaks. Composite resections of upper third lesions generally require vascularized reconstructions, usually in the form of a free tissue transfer (Chapter 39). Local vessels in the upper third region are limited and may require vein grafting. Postoperative radiation therapy may be required if the resected tumor has positive margins. Unfortunately, too often it leads to post-radiation damage that may necessitate free tissue transfer for coverage. This scenario needs to be thoroughly discussed with the patient in advance (Figure 17.2).
Radiation therapy to the chest wall is used in the treatment of lymphomas, large chest wall or pulmonary tumors, and for recurrent malignancies after previous resections (Chapter 92). Post-radiation complications in this patient population include radiation ulcers, infected wounds, persistent or recurrent tumors, and cardiac and pulmonary disorders. As the thoracic cavity houses a variety of vital organs, radiation damage to the chest wall can create a potentially lethal clinical scenario requiring immediate attention from the cardiothoracic surgeon as well as the plastic surgeon. These patients are often quite ill, requiring prolonged stays in the intensive care unit and a multidisciplinary team approach.
FIGURE 17.2. A 28-year-old female who received radiation therapy as a child for treatment of a blood dyscrasia developed basal cell carcinoma of scalp as an adult. A. Pre-op appearance. B. Tumor was resected and reconstructed with a free anterolateral thigh flap. Subsequently treated with local radiation to treat positive margins of sagittal sinus, resulting in marginal flap necrosis and wound breakdown. C and D. Salvage procedure performed with parascapular free flap.
The first step in evaluating a patient with one of these problems is to rule out the presence of new or recurrent tumor. This workup includes standard imaging studies such as chest radiograph, CT, or MRI, and possibly bronchoscopy. After the extent of tumor involvement is determined, it must be completely resected with negative margins before reconstructive options are considered. If tumor is not present, then the radiation ulcer or infected wound must be thoroughly debrided, and all fibrotic radiated tissue and foreign bodies resected. Chronic sinus tracts in the chest wall can often be traced to a sternal wire, retained suture, or persistent infected cartilage. Debridements are often performed serially, as it is often difficult to judge the extent of remaining nonviable tissue after a single procedure. As often seen in other anatomic areas, the extent of radiation injury exceeds what initially appears to be the boundaries of damaged tissue.
After resection and debridement is complete, the wound is evaluated to determine if it is partial or full thickness. Since the chest wall is a relatively thin structure, most chest wall defects following thorough debridement are full thickness and will require chest wall reconstruction prior to soft tissue coverage. Chest wall reconstruction is performed by either the thoracic surgeon or plastic surgeon experienced in chest wall reconstructions. Prosthetic material, such as Gortex (W.F. Gore, Inc., Phoenix, AZ) sheeting or Prolene (Ethicon, Inc., Sommerville, NJ) mesh, is usually employed for this reconstruction if the wound permits. The goal is to obtain an airtight seal at the time of closure in order to maintain appropriate intrathoracic negative pressure for respiration. The prosthetic material is then covered with a viable soft tissue flap, usually a musculocutaneous flap or a muscle flap with a skin graft. Flaps frequently used for chest wall reconstruction include one or both of the pectoralis major muscles, latissimus dorsi muscles, and rectus abdominis muscles, as well as the greater omentum5.
Advantages of the pedicled greater omental flap are its large surface area and excellent vascularity. Complete debridement of irradiated chest wounds often results in large irregular defects, and the omentum tends to cover these defects nicely since it can be molded into irregular defects quite easily (Figure 17.3). In many cases, the omentum with a skin graft is adequate and underlying foreign bodies in the form of mesh can be avoided taking advantage of the chest wall stiffness caused by post-radiation fibrosis.
The omentum is procured through an upper midline laparotomy incision, mobilized, and usually based on the right gastroepiploic vessels. Skin grafting is generally performed in a delayed fashion after a few days of dressing changes and one is sure that all of the transposed omentum is viable. This gives the plastic surgeon time to observe the omental flap, debride any nonviable portions, and re-advance or redistribute the pliable omentum as necessary. Disadvantages of the omentum are the lack of structural strength. It is simply a vascularized “carrier” for skin graft in this case. There is also the addition of an upper midline laparotomy and violation of a second body cavity, but its large size, malleability, vascularity, and acceptable donor defect make it an attractive option. The omentum can also be used for lower back closures by tunneling it through the retroperitoneum and paraspinous muscles.
FIGURE 17.3. A 45-year-old woman with bilateral breast cancer and multiple local recurrences, treated with extensive chest wall radiation, resulting in left chest wall osteoradionecrosis. A. Pre-op appearance. B. Osteoradionecrosis resected and reconstructed with pedicled greater omental flap and skin grafting. C. Note the well-healed flap and skin graft, surrounded by poor quality tissue with extensive radiation fibrosis.
Radiated wounds of the chest may involve, in rare circumstances, disruption of the aerodigestive tract or the heart with the great vessels. These have been dealt with on some occasions with intrathoracic muscle flaps4.
Because of the abundance of local muscles and the greater omentum, free tissue transfer is often not needed for most chest wall reconstructions. However, the radiated patient may not have adequate local muscles, and transposition of irradiated muscles can result in partial or total necrosis.6 If the greater omentum is not available, a free tissue transfer may be required in these extreme situations.15
As in the treatment of all radiation wounds, obtaining a well-healed chest wall relies on adequate debridement of nonviable tissue. Only then should chest wall and soft tissue reconstruction be attempted.
Gynecologic malignancies occasionally require extensive perineal resections and/or pelvic exenterations followed by radiation therapy resulting in perineal wounds not amenable to primary closure (Chapter 96). Similar perineal defects are created after abdominoperineal resections for anal or low rectal tumors. A pedicled rectus abdominis musculocutaneous flap is often the flap of choice. If this is not available, other options include the use of thigh muscles (rectus femoris and gracilis) and fasciocutaneous flaps (anterolateral thigh flap).
The greater omentum has been used for decades to treat the chronic vesicovaginal fistula and to fill the severely irradiated pelvis.16,17 It can also be employed to support a primary closure, or if no other options are available it can be used alone with a skin graft (although the omentum is sometimes resected by the extirpative surgeon in cases of gynecologic malignancies).
The aforementioned muscle flaps can also be used to reconstruct the vagina, in addition to filling the dependent pelvic defect. In the male, a musculocutaneous flap can serve the purpose of obtaining a healed perineal wound and filling the most dependent portion of the pelvic defect to promote wound healing, prevent evisceration, and attempt to prevent adhesions deep in the pelvis.
FAT GRAFTING FOR TREATMENT OF RADIATION DAMAGE
A fascinating recent development in the treatment of radiation damaged tissues is the use of autologous fat grafting (Chapter 44). Plastic surgeons have a long history of using vascularized fat in one form or another (TRAM flap, omental flap, dermal fat graft, etc.) for reconstructive purposes. Several authors have reported clinical improvement in radiation damaged tissue following fat grafting. For example, Sultan et al.18 studied the effects of fat grafting in radiation damaged skin and concluded that fat grafting attenuated inflammation in acute radiodermatitis and slowed the progression of fibrosis in chronic radiodermatitis in a murine model. It has been hypothesized that clinical improvements seen in radiation-damaged skin treated with autologous fat grafting is related to the adipose-derived stem cells present within the stromal vascular fraction of the fat graft. This is a new and exciting area of reconstructive surgery and certainly warrants further investigation and exploration.
While radiation therapy has many benefits, late changes following irradiation have been well described and offer the plastic surgeon many reconstructive challenges. Each anatomic location offers unique problems to the plastic surgeon. But the basic tenets of treating irradiated wounds are the same, regardless of anatomic location:
1. Establish a diagnosis (rule out malignancy and determine the extent of tissue damage).
2. If tumor is present, perform the appropriate workup and treatment.
3. Thoroughly debride the radiated wound of all nonviable tissue and foreign bodies and transfer as much tissue as possible to permit resection of even more of the periphery in questionable wounds.
4. After adequate debridement has been obtained, usually in stages, reconstruct osseous defects with vascularized bone and soft tissue defects with well-vascularized, nonirradiated soft tissue. All neurovascular bundles, bone, tendon, and prosthetic material must be covered with healthy soft tissue.
5. In the case of pedicled flaps, it is better to base a flap on a nonirradiated pedicle, and in the case of free tissue transfer, it is best to use nonirradiated recipient vessels. Consider preoperative evaluation of vessels and anticipate the need for vein grafts.
6. Reconstruction of these defects is challenging and fraught with high complication rates, so always have a “plan B” in mind and anticipate complications.
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