Principles of Craniofacial Surgery and the Management of Complications

59  Principles of Craniofacial Surgery and the Management of Complications Timothy A. Turvey, Brent Golden, Ramon L. Ruiz

KEY POINTS • A problem list should be established, and a comprehensive treatment plan should be developed. • Understanding the basic principles of facial skeleton surgery is important.

• The surgeon must always be aware of intraoperative and postsurgical complications.

INTRODUCTION

Poor outcomes in craniomaxillofacial surgery occur for many reasons, the most common being inadequate preoperative evaluation and lack of an organized treatment plan. From a surgical perspective, the establishment of an accurate diagnosis is a critical initial step in the management of patients with craniofacial malformations; because there are substantial variations in the expression of these conditions, formulation of the problem list must clearly define specific dysmorphic features and their associated functional and aesthetic impairments. A description of a patient as having facial features consistent with a particular diagnostic entity (such as, Crouzon disease or Treacher Collins syndrome) is of limited therapeutic value. Preoperative physical examination is composed of both subjective evaluations of facial esthetics and quantitative anthropometric measurements of craniomaxillofacial proportions and symmetry. Measurement analysis of anatomical landmarks using lateral and posteroanterior cephalometric radiographs is invaluable to understand the relationships of the different structures within the craniomaxillofacial complex. The use of computed tomography (CT) scans for preoperative evaluation and quantitative postoperative assessment has become routine. Stereolithographic skull and facial models that are fabricated from the CT data are indispensable for planning complex cases or complex surgical movements. Virtual models of the skeletal and soft tissue components of the cranium and face are increasingly useful for visualization and planning purposes. Anatomical dental casts mounted on a semiadjustable articulator document occlusal and jaw relationships and constitute another important component of the presurgical database. Articulated casts are also employed to confirm proposed surgical movements (model surgery) and to fabricate splints used during the corrective surgical procedures. Information collected during the presurgical evaluation must then be integrated into a surgical treatment plan. Operations should be designed to improve the specific dysmorphic features of an individual, not the syndrome. For example, middle face deficiency is not expressed uniformly in the orbits and at the occlusal plane in patients with Crouzon disease. Consequently, a “standard” operation should not be employed

Since Tessier introduced the concept of craniofacial surgery in 1967, the principles and operative techniques of this unique surgical discipline have continued to evolve.1 Tessier’s original work with craniofacial surgical techniques involved children and adults with congenital malformations, including craniofacial dysostosis and facial clefts. Experience with the correction of craniofacial anomalies in infants then required modification of the original principles. Subsequent modifications of Tessier’s techniques now provide the craniofacial surgeon with improved access for tumor resection, management of posttraumatic deformities, and superior esthetic outcomes in the correction of congenital anomalies and cosmetic surgery.2,3 Further technical refinements continue to build on the original principles of craniofacial surgery and expand the applications of these techniques for the correction of facial deformities. One purpose of this chapter is to present principles that may be applied during craniofacial surgical procedures undertaken in the management of a variety of conditions. Another purpose of this chapter is to discuss the complications associated with this surgery.

PRINCIPLES Defining the Problem and Developing a Treatment Plan Comprehensive management of patients with craniomaxillofacial malformations is best accomplished by a multidisciplinary team (MDT) of experienced health care providers including the surgeon. Patients with craniofacial syndromes often have defects involving other organ systems; therefore, careful evaluation of the patient’s overall medical condition and identification of potential surgical risk factors must be part of the preoperative work-up. In children, detailed examinations of neurological and visual function, speech, and airway status are essential early in life and then longitudinally as the child grows and undergoes treatment. Other nonsurgical issues including the patient’s emotional state, familial support and structure, and other psychosocial stress factors must not be overlooked.

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CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications

for each patient with this condition. If a basic operation is used, variations should be tailored to address specific dysmorphic features, enhance aesthetic outcomes, and meet the functional goals. Development of the final surgical treatment plan also requires input from the patient and family.

SURGERY IN THE GROWING CHILD Timing of intervention is critical when planning for reconstructive surgery in the growing child. Remaining growth potential of the affected structures must be considered together with the diagnosis and problem list. It seems clear that surgery treat­ ing the craniofacial skeletal structures may improve threedimensional proportions at the time of intervention, but growth patterns are at best unaffected, and at worst hindered, by surgery prior to maturation. For this reason, the best time for skeletal surgery according to the biology of the craniofacial region is when structures are nearly their adult size and growth potential is declining. Because growth proceeds craniocaudally, specific interventions often proceed in a staged fashion, depending on the structures affected following a general pattern of cranial procedures early in life, orbitozygomatic reconstruction in the elementary school age child, maxillary and mandibular reconstruction in the teenage years, and nasal reconstruction in the teenage years as well. Of course, actual or risked functional disturbances (such as, increased intracranial pressure, poor skeletal or soft tissue protection of the globe, chronic or acute obstructive airway events, or severe psychosocial detriment) can and often do lead to earlier surgery with the understanding that residual growth is likely to lead to re-emergence of the original abnormal proportions. Because the soft tissues of the face are dependent on the skeletal structures for their support, as a general rule earlier surgery has more favorable maintenance of correction and is performed as early as is reasonable relative to the health and functional concerns (breathing, feeding, vision) of the child.

Placement of Incisions Utilization of incisions that minimize visible scars is an important principle of craniomaxillofacial surgery. To accomplish this, the coronal and intraoral incisions should be used whenever possible. The transconjunctival approach to the orbit is useful but rarely necessary. Facial incisions, no matter how well camouflaged, should be avoided if possible. Sometimes the resulting facial scar is more obvious than the soft tissue problem that it was intended to correct. For instance, midline forehead scars secondary to skin excision may appear as unsightly as widened eyebrows. Coronal Incision The coronal incision is a versatile and cosmetically acceptable approach for access to the cranial vault, cranial base, forehead, nose, upper middle face, and orbits. With the use of this incision, inferior eyelid or transconjunctival access to the orbit is not necessary in most cases. The incision is placed from one supra-auricular area to the other, and the degree of skeletal exposure required for a given procedure dictates the inferior extent of the incision. When access to the zygoma and infraorbital rims is necessary, the incisions must be extended farther inferiorly. The patient’s hairline is the primary consideration in placing the incision. Although anterior extension at the midportion of the coronal flap may

enhance flap retraction and access to the midface, the resulting scar may subsequently become obvious with male-pattern baldness. Our preference is to place the incision across the top of the head rather than carrying it toward the forehead. The use of a postauricular coronal incision eliminates visible scars in the preauricular area and decreases the risk to the frontal branch of the facial nerve in reoperated patients, but it may also limit exposure anteriorly.4 Placement of this incision farther posteriorly in the scalp is also beneficial in children, in whom migration of the coronal scar may occur with growth. When secondary operations are performed, it is preferable to re-incise through the original scar. Although it may be tempting to place the incision in a different location, consideration must be given to the effect of the previous scar on flap perfusion and wound healing. Use of a zigzag (stealth) incision avoids a straight-line scar and is particularly useful in patients with short hair.5 The additional blood loss associated with a greater incision length and longer closure time may offset the benefit. After a 1-cm strip of hair has been shaved along the proposed incision line, the area of the incision is injected with a diluted solution of 1% lidocaine with epinephrine (1 : 200,000). This reduces bleeding and helps dissection along the subaponeurotic plane. Sterile saline may be injected freely into the subgaleal plane from the incision line to the forehead with the use of a spinal needle. Cross-hatch markings aid in the reapproximation of wound margins during flap closure. Because the scalp has a rich vascular supply, the incision is carried out in segments with application of hemoclips. Bipolar electrocautery is used to obtain hemostasis; this has a minimal effect on the adjacent peripheral hair follicles. The use of monopolar electrocautery is discouraged because of the increased risk of destroying regional hair follicles, which may result in a more visible scar. Adequate hemostasis is especially important in infants and young children because of the potential loss of their blood volume. Once the pericranium is identified, a plane of dissection is established above it. Dissection proceeds rapidly and bloodlessly to the forehead in this supraperiosteal plane. At the hairline, an incision is made through the pericranium and dissection is then continued subperiosteally to expose the facial skeleton. Subperiosteal dissection of the forehead and face reduces the risk of facial nerve injury. Remaining within the subperiosteal plane during dissection over the facial skeleton is crucial in order to avoid injury to the facial nerve. Bleeding from vessels perforating the cranium can be controlled with bone wax. In infants and young children, care must be exercised when dissecting over open sutures, especially midline sutures, to avoid venous sinus hemorrhage and injury to the meninges. Care must also be exercised when establishing a plane of dissection over the temporalis muscle. The natural plane of dissection is subgaleal. Within the region over the temporalis muscle, the plane should be deepened to the level of the muscle fascia (superficial layer of the deep temporal fascia). The temporoparietal fascia, which is superficial to the fascia of the temporalis muscle and is an extension of the superficial musculoaponeurotic system, invests the temporal branch of the facial nerve. Deepening the incision to the level of the temporalis muscle fascia avoids the nerve and leads to subperiosteal dissection of the facial skeleton. The supraorbital nerves sometimes restrict flap mobility and dissection of the periorbita. Removal of the bony floor of the foramina using a small osteotome is often required to release the supraorbital neurovascular bundles and permit further mobility of the flap.

CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications Closure of the incision in layers, even after facial advancement exceeding 15 mm, is usually not a problem. The lateral canthus is resuspended to the fascia over the temporalis muscle in an upward and posterior direction. Dissection of the posterior scalp in the subgaleal plane is sometimes necessary to assist closure. Oral Incision The use of transoral approaches to the facial skeleton provides wide exposure while concealing scars, and this is a useful component of sound craniofacial surgical principles. By combining oral incisions with the coronal incision, the entire craniofacial skeleton may be dissected and visualized. In general, a horizontal incision from the molar region of the maxilla to the opposite molar region adequately exposes the lateral walls of the maxilla, inferior orbital rim, pterygomaxillary juncture, zygomatic buttress, and nasal cavity. When the maxilla is mobilized at the Le Fort I level, a circumvestibular incision under the upper lip is used. The bilateral cleft maxilla is an exception, and an anterior mucosal pedicle on the premaxilla must be maintained, even if previous bone grafting has united the segments. When Le Fort III and Le Fort I osteotomies are combined, the preservation of an anterior soft tissue pedicle provides additional perfusion to the middle face, which is already vascularly compromised by the Le Fort III osteotomy. The entire facial aspect of the mandible may also be accessed through an oral mucosal incision. An incision through the mucosa of the lower lip is normally used to approach the anterior mandible, such as when a genioplasty or a mandibular subapical osteotomy is performed. If access to the mandibular body or ramus is necessary, incisions along the external oblique ridge may be extended. The lingual soft tissues provide adequate perfusion to the mandible during dissection and retraction of the buccal tissues. Therefore, it is important to maintain these lingual attachments during mandibular osteotomies. When inferior border osteotomies are undertaken, preservation of the attached genial musculature assures better long-term survival of the mobilized segment. If this procedure is conducted as a free bone graft, resorption of the segment is predictable.

Subperiosteal Dissection Of importance to craniofacial skeletal operations is generous subperiosteal dissection of the facial skeleton, which is sufficient to permit visualization and instrumentation. This is the case when the facial skeleton is exposed through a coronal incision and in any transoral approach to the maxilla, zygomatic complex, and mandible. When the orbit is involved in the osteotomy, complete subperiosteal dissection is necessary to relax tension on the globe, as well as to permit adequate access. Flap relaxation may be achieved by releasing the supraorbital neurovascular bundle and freeing the periorbita around the circumference of the orbit. When additional periosteal stripping and uncovering of the medial orbital wall is required, the anterior and posterior ethmoidal arteries may be cauterized and divided. Dissecting more than 15 mm toward the apex from the orbital rim is seldom necessary. Although further posterior dissection is possible, the risk of optic nerve injury increases proportionately. The attachment of the medial canthal tendon to the frontal process of the maxilla is identified and protected during the dissection, unless repositioning is planned. Preservation of this

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structure on the anterior lacrimal crest avoids the uncertainties of reattaching it. If the medial canthus is abnormally located, it should be repositioned at the completion of the surgery. Subperiosteal dissection of the nasal bridge is of importance when onlay bone grafts are placed or when a portion of interorbital bone is to be excised, as with correction of hypertelorism. Similarly, dissection of the lateral walls of the maxilla, zygomatic buttress, and arch is necessary for placement of contour bone grafts. Dissection is also important for coronal flap relaxation and to permit facial advancement and soft tissue redraping at the completion of surgery. Confining the dissection of the facial skeleton to the subperiosteal plane minimizes the possibility of facial nerve injury. When facial nerve injury occurs during craniofacial procedure, the frontal and temporal branches are most frequently involved. Identification of the subperiosteal plane posteriorly and anteriorly before dissection around the zygomatic arch further assists in the prevention of this injury.

Adequate Cooling When Using Power Cutting Instruments A basic principle of performing surgery on bone is to prevent overheating, which damages the cells adjacent to the osteotomy. Overheating is common, however, and some authorities consider it trivial. Osteocyte damage from overheating, especially when autogenous bone grafts are used, probably has more significant histological effects than clinical ramifications. Relapse associated with some craniofacial procedures may, however, be related to bone healing problems secondary to heat damage to the bone. Today there is greater reliance on screw and plate fixation of osteotomies. Inadequate use of coolants at the time of screw hole placement may result in thermal bone injury, poor hardware retention, and unstable osteotomized segments. Harvesting of bone grafts with the use of power instruments was the likely reason for the poor initial success rates of craniofacial bone grafts to the cleft maxilla.6 When the cranial diploë is harvested with a curette rather than a craniotome, success is similar to that observed with the ilium as the donor site.7 Using power instruments without adequate cooling apparently damages the cells and diminishes the osteogenic potential of the bone graft. In no other aspect of craniofacial surgery has the importance of using adequate coolant and slow-speed rotary instrumentation become more apparent than with the placement of craniofacial endosseous implants. In this setting, it is crucial to maintain the viability of the cells adjacent to the implant to allow for osseointegration. Reduction of heat damage by adequate irrigation and use of slow-speed rotary instruments is critical to success.

Completion of Osteotomies Under Direct Visualization Adequate mobilization of skeletal segments during total midfacial advancements can only be accomplished when osteotomies are complete. The combination of intracranial and subcranial (anterior) approaches to the craniomaxillofacial region allows retraction and protection of the brain and globes so that the procedure may be carried out safely under direct visualization. The craniotomy provides access for visualization and pro­ tection of the brain throughout the operative procedure. When operations are conducted in the temporal fossa, adequate

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CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications

dissection of the fossa below the sphenoid wing affords protection to the temporal lobe during the osteotomy. This is especially important in Apert syndrome, in which the temporal lobe tip may extend forward into the lateral orbital rim. As previously described, wide exposure of the orbits and middle face is accomplished through a coronal incision. Meticulous dissection and retraction of soft tissue structures is important for visualization and thorough instrumentation at the osteotomy sites. Once an osteotomy has been completed, the bone cuts should be tested with a thin osteotome in order to identify areas of incomplete separation and prevent unintended fractures. Attempts to mobilize facial bones after incomplete osteotomies may result in fracture disruption of the segments, inadequate advancement, and relapse. This most frequently occurs during movements at the Le Fort III or frontofacial (monobloc) levels. Inadequate separation of the posterior maxillary walls and perpendicular portion of the palatine bone, which are impossible to visualize completely, contributes to this problem and may result in disruption of the zygomatic portion of the orbit. The use of osteotomes and specially designed bone spreaders assist in the completion of pterygomaxillary separation and minimize the risk of associated fractures. When fractures occur, complete mobilization must still be accomplished. Repair of the involved segments by plate fixation is indicated; when this is appropriately performed, it seldom results in a problem (see Management of Complications section). Simultaneous intracranial and subcranial approaches to the craniofacial region are also used for direct visualization during midline procedures. With the use of magnification, this exposure allows removal of interorbital bone and preservation of olfactory nerve filaments in the correction of hypertelorism.8

Stabilization and Fixation Appropriate stabilization of skeletal segments and bone grafts is necessary for successful outcomes in craniofacial surgery. Inadequate stabilization contributes to relapse and infection, and the use of bone plates and screws may minimize problems. The use of bone plates and screws has significantly improved the outcome of most craniomaxillofacial surgical procedures. Problems with the use of titanium plate and screw fixation in the pediatric population arise from cranial remodeling (endocranial bone resorption, exocranial bone deposition), damage to developing teeth, and restriction of growth.10,11 An added concern is the unknown long-term effect of the implanted metals over the lifespan of the patient. When titanium plates and screws are used in pediatric patients, removal should be considered within 9 months following surgery. Even in this short time, the removal may be difficult because of osseointegration of the hardware. The major issues with using titanium plates and screws in adults are palpability and thermal sensitivity. Biodegradable bone plates and screws are now available, and their use has been beneficial, especially in pediatric craniofacial surgery. The materials developed and marketed are made principally from polylactate. Other polymers, such as polyglyconate, can be added to speed biodegradation. The strength of the materials varies significantly depending on the exact formula, manufacturing process, sterilization process, and intraoperative handling. Care must be exercised when selecting materials to be used. Different materials should be used depending on the patient’s age, area of the craniofacial skeleton to be stabilized, and the strength requirements (see the Management of Complications section for more details).12,13

Overcorrection

Placement of Bone Grafts

Relapse is a problem familiar to those involved with osteotomies of the craniofacial skeleton. Three types of postoperative skeletal relapse may occur. The first is movement of the bones toward their original position. This occurs mostly because of inadequate mobilization and stabilization. The osteotomized segments must be adequately mobilized and positioned to achieve the desired result. Additionally, associated soft tissues must be adequately relaxed to accommodate the skeletal movements. The use of rigid internal fixation devices provides better stability of the cranial and midfacial regions. This is less true in the mandible, where musculoskeletal adaptation is required for stability.9 The second type of relapse occurs because of disproportionate growth. This growth may involve the operated skeleton, adjacent structures, or both. The third mechanism for relapse is related to bone remodeling or pathological changes such as condylar resorption. In all three conditions, the result is similar (i.e., a return to the original condition). Overcorrection of the mobilized skeleton is more important in children because continued growth is expected. The amount of overcorrection is variable and depends on the skeletal unit operated, the vector and magnitude of the movement, and expectation of growth. In children, overcorrection of the occlusion should be employed, because postsurgical growth is the key to the result. Overcorrection of the mobilized skeletal segments in adults is more controversial. In adults, occlusion should determine the position of the maxilla and mandible, providing that patients have undergone appropriate orthodontic preparation.

The use of fresh autogenous bone grafts provides the most predictable results in craniofacial surgery. As a general rule, all bony defects should be grafted in order to assure adequate regeneration and continuity. Formerly, ilium and rib were the most frequently used donor sites. The site was chosen according to the desired bone consistency. The cranium has now become the most favored site.14 The proximity to the surgical site, ease of harvesting, and quantities of bone available make the calvaria an attractive alternative. Additionally, the consistency of bone in the cranium (dense cortical) and its rich haversian network allow it to revascularize quickly and resorb minimally.15 Consequently, cranial bone grafts are excellent for use in recontouring the craniomaxillofacial skeleton. Although the ilium remains the favored donor source for grafting of clefts, adequate quantities of cancellous bone may also be harvested from the cranium when necessary with equally good results.16 Allogeneic bone, lyophilized cartilage, and alloplastic materials have all been used in craniofacial surgery. Although success has been achieved with the use of these materials in certain instances, none has the same success rate or predictability of fresh autogenous bone. When bone grafts are placed they should be wedged into defects or retained in position by securing them with screws or plates.

Management of Dead Space The elimination of dead space during closure of the craniomaxillofacial region is critical for sound surgical practice.

CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications Dead space resulting from craniofacial procedures is resolved by meticulous closure of tissues, placement of bone grafts, and obliteration with soft tissue flaps or free fat. Forward advancements of the craniofacial skeleton and anterior cranial vault result in the creation of extradural retrofrontal dead space and communication with the nasal cavity.17 Potential complications of residual dead space include delayed healing, cerebrospinal fluid leaks, and infection.18,19 The management of this space in the anterior cranium following frontofacial or forehead advancement remains controversial. Expansion of the frontal lobes and relatively rapid filling of the residual intracranial space has been well demonstrated in infants and young children.17,20 This observation supports the conservative management of dead space in younger patients. More gradual and less complete filling occurs in the adult. This may be particularly troublesome when the space communicates directly with the nasal cavity. Sealing the nasal cavity from the cranial fossa is accomplished with primary repair of the nasal mucosa. When this is not feasible, an anteriorly based pericranial flap may be inserted for coverage of the anterior cranial base. Use of fibrin glue in the reconstruction of the anterior cranial floor also provides a temporary seal between the cavities and allows for reepithelialization of the nasal mucosa.21 When forehead procedures are performed and the frontal sinuses are present, management of the dead space is achieved by cranialization, complete removal of the mucosal lining, and obliteration of the nasofrontal ducts with bone grafts or free fat. The placement of bone grafts into bony defects is important for closure of dead space and rapid healing. These bone grafts should be wedged or stabilized with screws to prevent migration. Additionally, defects within the temporal fossa following facial advancements or orbitozygomatic reconstruction in Treacher Collins syndrome should be filled by advancement of temporalis muscle flaps. This eliminates the dead space, and the defect is confined to the hair-bearing area of the scalp. A layered closure of the coronal incision is required for elimination of dead space and an optimal aesthetic result.22 The lateral canthus is dissected during exposure of the orbital rims and lateral wall, and these structures must be resuspended. Sutures are passed through the canthus and secured to the lateral orbital rim or temporalis muscle fascia. When the temporalis muscle is stripped from the lateral temporal crest or fossa, it should be reattached to the lateral orbital wall and temporal ridge in order to prevent bitemporal defects. Closure of the subcutaneous tissues and galea is accomplished as a separate layer. Sutures or surgical staples are used for cutaneous closure. The use of chromic gut on the skin in children is effective and may obviate the need for postoperative suture removal. Until the nasopharyngeal mucosa seals, communications with the nasal cavity allow air leaks that may result in subcutaneous emphysema or a pneumocephalus. To prevent this type of airflow, postoperative endotracheal intubation may be extended or bilateral nasopharyngeal airways placed for a 3- to 5-day period.23 In addition, sinus precautions and restriction of nose blowing further limit reflux of air and fluid during the postoperative period.

Perioperative Management Preoperative evaluation of the craniofacial surgical patient must include a complete physical examination, appropriate laboratory tests, and compatibility studies for blood transfusion. Recent advances in transfusion medicine have made possible

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the use of autologous blood donated preoperatively by the patient. Standard intraoperative monitoring consists of electrocardiographic leads, pulse oximetry, capnography, temperature probe, and a precordial stethoscope. Central venous catheters are useful for preoperative hemodynamic monitoring and provide additional vascular access. The use of an arterial blood pressure line is required during long procedures or when controlled hypotensive anesthetic techniques are employed. Arterial lines provide constant blood pressure measurements and access for obtaining serial blood gas samples. Hourly evaluation of urine output, using a catheter, is a useful and easily quantifiable indicator of renal perfusion and volume status. When extensive dural lacerations or cerebrospinal fluid leaks occur, primary repair or patch grafts should be accomplished. Lumbar drains in the subarachnoid space during the perioperative period are sometimes helpful. At completion of surgery the patient is transported directly to a critical care unit (pediatric or surgical) by the anesthesiologist, surgeon, and intensivist. Joint management by the surgeon and critical care specialist allows close monitoring of the patient’s respiratory, hemodynamic, and neurological status. In the intubated patient, sedation must be carefully administered to allow serial neurological examinations during the immediate postoperative period. Measurement of serum electrolytes and blood counts must be performed frequently during the initial 24 hours following operation. In patients who have received large blood transfusions, evaluation of platelets, prothrombin time, and partial thromboplastin time is necessary because of the potential for dilutional coagulopathies. The decision to extubate the patient is based on alertness, respiratory parameters (level of ventilator support, tidal volume, negative inspiratory force), and degree of edema. Administration of short-term, high-dose steroids during the immediate perioperative period is useful in reducing postoperative edema. Recollection of the massive edema seen in patients undergoing orthognathic procedures who were not treated with steroids is sufficient to recommend their perioperative use for craniofacial surgery. By reducing edema of the craniofacial region, the risk of excessive pressure on the globes is reduced, as is discomfort. The patient’s mental status must be monitored closely as periods of euphoria, psychosis, and mild depression are possible during and immediately after steroid administration. Perioperative antibiotic coverage is indicated for craniomaxillofacial surgery, and the exact regimen is determined by the type of surgical procedure. The duration of the antibiotic administration also varies. When facial osteotomies are performed without bone grafts, 24-hour coverage is sufficient. For major procedures involving bone grafts or operations that result in the creation of dead space within the craniofacial region, antibiotics are continued for at least 10 days postoperatively. Penicillin type antibiotics remain the antibiotic prophylaxis of choice for procedures that are done through transoral incisions. For operations using coronal or other cutaneous incisions, a first-generation cephalosporin is effective against most Staphylococcus, Streptococcus, enteric, and gram-negative species and some anaerobes. First-generation cephalosporins, however, have variable activity against Haemophilus influenzae. Aminoglycosides provide additional coverage of Pseudomonas and Enterobacteriaceae. They do not cover Streptococcus or Listeria but act synergistically with penicillins against these organisms.

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CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications

MANAGEMENT OF COMPLICATIONS Introduction From the outset of the development of craniofacial surgery, Tessier was concerned about protection of the brain and the ocular globe and maintaining separation between the nasopharynx and the cranium. He counseled others about the importance of adequate brain and orbital dissection and protection, as well as gentle retraction. Initially, he and his neurosurgical colleague reinforced the skull base with a skin graft that was placed prior to the actual craniofacial procedure. At a second stage, they then proceeded with orbital translocation and were able to maintain separation of the two cavities. After experience, they found that they were able to mobilize the nasal mucosa for primary closure or were able to recruit other local tissues to form the barrier and eliminate the need for the skin graft. As the popularity of craniofacial surgery increased, it is remarkable that more complications were not reported, especially brain injury and blindness. For the past four decades that the senior author has been involved with craniofacial procedures, complications have been rare and the greatest frequency has been infection. This section of the chapter will deal with complications and management.

Intraoperative Complications

Inadvertent Fracture The most common intraoperative complications are associated with incomplete osteotomies and mobilization attempts. Mobilization of major facial osteotomies (Le Fort III, monobloc, or facial bipartition) is met with resistance. When resistance to mobilization is met, osteotomy lines should be retraced with osteotomes to be certain that they are completely severed. The inexperienced surgeon may apply more force, which results in uncontrollable fractures at other areas of weakness in the facial skeleton. When inadvertent fractures occur, attempts should be made to complete the mobilization at the desired osteotomy line. Stabilization of the fracture can be achieved with bone plates and screws. The most common area where inadvertent fractures occur is along the inferior orbital rim. The reason is usually incomplete severance of the posterior maxillary wall and perpendicular portion of the palatine bone, which extends to the orbital floor. When inadvertent fracture occurs, immediate repair with a bone plate usually salvages the situation (see earlier Completion of Osteotomies Under Direct Visualization section). The next most common fracture is palatal split. Providing that the mucosa remains intact, this is normally of little consequence, as long as an occlusal splint is used to control the maxillary arch form. If the palatal soft tissue is torn, attempts to repair it should be undertaken to prevent oronasal fistula formation. This inadvertent fracture also occurs during mobilization, and it is almost always attributable to the oronasal disimpaction forceps. Patients who have clefts involving the hard palate are predisposed to this complication. Patients with Apert syndrome who have highly arched and narrow palates are also predisposed. Hemorrhage Careful subperiosteal dissection of the face and orbit will reduce the risk of intraoperative hemorrhage. Separation of the poste-

rior wall of the maxilla and pterygoid plate has the highest likelihood of bleeding from the internal maxillary arteries or the terminal branches. Control of the bleeding with packing or direct visualization and use of vascular clips or electrocautery are the best methods. The use of diluted epinephrine (1 : 100,000) injected into the bleeding area is also a useful maneuver. All bleeding responds to pressure, and packing left in place for days may be required in unusual circumstances. In such cases, removal occurs in the operating room under general anesthesia. Interventional neuroradiology is another technique to be considered when recalcitrant bleeding cannot be controlled. Ligation of the external carotid artery may provide temporary relief, but collateralization occurs quickly. This should be reserved for desperate circumstances. External carotid ligation may make interventional radiology impossible or less predictable and effective. Modified hypotensive anesthetic techniques with systolic pressure of 90 mm Hg should always be employed with craniofacial osteotomies to help reduce bleeding. With craniofacial surgery, blood loss is expected even with the most experienced staff. There is no excuse for not being prepared to replace blood. A diligent anesthesiologist who is familiar with this surgery and anesthetic technique should be in attendance. Careful monitoring of blood loss and urine output, especially in infants and children, is critical. Blood replacement is necessary in many patients undergoing craniofacial surgery, and cross- and type-matched blood should always be available. Autologous blood and donor-directed blood are popular because of the reduced risks of disease transmission. At least two units should be available for all patients. Single-dose injection of erythropoietin (600 units/kg up to 20,000 units) has also been used successfully to reduce the need for transfusion, but this should be done in addition to having typed- and crossed-matched blood available.24 Another technique for reducing the need for blood transfusion is the use of tranexamic acid during surgery.25 Some patients refuse transfusion of homologous blood or its products. When cranial nerve deficits and increased intracranial pressure are the presenting symptoms and homologous transfusion is refused, the surgeons and anesthesiologists involved must decide their level of participation. Surgery to address only the functional issues rather than the cosmetic concerns is the compromise. The goal of surgery in these circumstances is to reduce intracranial pressure, reduce the complexity of surgery, and minimize the need for homologous transfusion. Intraoperatively, blood suctioned from the field can be filtered and returned to the circulation. Hemodilution, in which whole blood is drawn before surgery and replaced with lactated Ringer’s solution three times the amount withdrawn of blood, may also help with these difficult circumstances. The withdrawn whole blood is then transfused at the end of surgery. Orbital Fat Herniation The basic principle of orbital surgery is complete subperiosteal dissection. One of the most commonly observed complications is periorbital fat herniation through violation of the periorbita. When this occurs, the fat is never excised and moistened gauze is placed over the fat to help contain it while the operation is performed. No attempt is made to return the periorbital fat through the periorbita, nor is the periorbita ever sutured.

CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications Postsurgical Complications

Infection Prophylactic antibiotics should always be administered, and this combination with appropriate surgical techniques helps minimize infection. When infection is detected, it should be managed immediately (proactively). Achieving adequate drainage, débridement, and irrigation of the region helps contain and eliminate the infection. Removal of the source (usually a loosened bone graft) is the key. Although antibiotics are administered, elimination of the source of infection is critical. Hematomas in the temporal fossa are common and difficult to distinguish from infection. In the absence of systemic signs and symptoms of infection, these are left to resolve on their own. Distinguishing infection from an exuberant inflammatory response to the biodegradation of bioresorbable plates and screws is sometimes difficult, but the distinction is important because with both scenarios there is swelling but the inflammatory response is not accompanied by systemic illness, leukocytosis, and so on. Complications of craniofacial surgery remain rare but infection has the highest risk (occurring in less than 2%). The perioperative use of antibiotics, meticulous attention to hemostasis, obliteration of dead space and wound closure, as well as sealing the nasopharynx from the cranium, seem to be important factors in reducing the rate of infection. When infection occurs, immediate attention to the establishment of drainage, irrigation, identification of the source, and elimination from the surgical site seems to give the best prognosis. If incisions for drainage can be made in the hairbearing area of the scalp or intraorally, this will minimize facial scarring. Wound cultures can help identify particular organisms and help target antibiotic therapy. If long-term intravenous antibiotics are needed, the early placement of a peripherally inserted central catheter (PICC) line can reduce morbidity and hospitalization. When meningitis is suspected, cerebral spinal fluid sampling and culture confirms the suspicion. Appropriate antibiotics must be administered intravenously for at least 3 weeks once the diagnosis of meningitis is confirmed. Complications of Bone Plates, Devices, and Screws Just as metallic bone plates and screws revolutionized craniofacial surgical techniques during the mid-1980s, biodegradable bone plates and screws have had a similar impact on craniofacial surgery. Titanium bone plates and screws permit stabilization of bone segments with greater rigidity than wire fixation, and therefore this technology maintains the shape and position of the reconstructed segments during the healing phase better than wire fixation. A problem with titanium bone plates and screws is their restrictive effect on head and facial growth in infants and children. Their affinity for bone allows the material to osseointegrate. The positional permanency of the material often results in it becoming submerged in the skull or even coming in contact with the dura as endocranial resorption and exocranial deposition of bone occurs in response to brain growth. The major problem that results is during reoperation. Locating the material is sometimes difficult, because it is completely submerged in bone, and often it is impossible to entirely remove it without complete excision of the bone. To date no pathology is associated with the use of titanium, even

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when it is in contact with or perforates the dura. The use of biodegradable bone plates and screws makes reoperation of the area much easier. The major appeal of biodegradables is their lack of permanency. Although not as strong as titanium, the polymers usually have adequate strength to permit skull reshaping and to maintain position during the healing phase. The basic ingredient is polylactate, and many manufacturers add polyglyconate and trimethyl carbonate to regulate the speed of biodegradation and workability of the material. For these materials to biodegrade, a low-grade inflammatory response is required. The initial reaction is hydrolysis, followed by phagocytosis and further degradation and elimination via the Krebs cycle as carbon dioxide and water. The amount of inflammation incited is variable and depends on the individual cellular response, amount of materials used, exact composition of the material, amount and quality of the soft tissue overlying the material, and vascularity of the region. Exuberant inflammatory response requiring removal has been observed in approximately 5% of those patients undergoing lower facial surgery.26 Acute swelling and sterile abscess formation is typical when this response occurs. Swelling, erythema, and fistula are typical expressions in the oral mucosa when the material is used in the lower face. Periorbital swelling and fluctuations with swelling in the scalp overlying the area where the material has been used are typical in the orbital and skull regions. When these responses are observed, removal is sometimes necessary depending on the intensity of the response including pain. When the response occurs in the cranium, observation is most prudent but dependent on presenting symptoms. Periorbital and oral mucosa presentations are usually treated more aggressively with the intention of controlling the point of drainage. The scalp is thick and in general has good blood supply compared with the thin periorbital skin and oral mucosa. Observation of the scalp rather than surgical intervention is usual if pain is not a significant factor. It must be emphasized that the reaction is typically a sterile process, not infectious, and therefore antibiotics usually are not effective in resolving the situation. Distraction devices for the craniofacial region have increased in popularity in the late twentieth and early twenty-first centuries. Devices come as either external frame devices secured to the cranium by pin fixation or internal devices that are buried and secured to the distraction segment with bone screws. Complications in the external devices include infection or pin related injury. The internal devices are even more likely than the external to develop infection, and in both groups reoperation on the order of 10% may be seen to address a variety of complications.27 Ophthalmological Complications Blindness is a possibility with craniofacial surgery. Direct injury to the optic nerve should only be possible when dissection to the optic canal is taken. This is only necessary when optic nerve decompression is undertaken. Fracture of the skull base involving the optic canal is another potential but rare source of blindness. If vision is affected postsurgically, it is usually transient and secondary to edema rather than direct cranial nerve injury. Indirect injury to the nerve is possible from traction on the globe during surgery, and this should be avoided. Periorbital edema following craniofacial surgery is typical and should be expected. Because the periorbita is usually

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CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications

dissected around the entire orbit including the lateral wall, optic nerve injury, secondary to the pressure of swelling, is unusual. Diplopia Edema in the extraocular muscles creates an imbalance in muscle function and consequentially double vision. Temporary diplopia is an expectation of surgery and not necessarily a complication. Controlling the swelling by minimizing dissection, retraction with gentle care and reducing trauma to the muscles are obvious ways to reduce edema. The administration of intravenously administered corticosteroids (methylprednisolone) preoperatively, intraoperatively, and postoperatively for 24 hours also helps reduce edema. When diplopia is secondary to periorbital swelling (and this is the most common cause), time and encouragement is the wisest course. Diplopia can also be caused by muscle entrapment or impingement by repositioned orbital structure or bone grafts. Muscle swelling is the most common cause; but when pain or physical impairment is present, a postsurgical CT scan can help identify the problem. Forced duction should always be performed at the completion of surgery. If ocular motility is restricted, the problem can be addressed immediately. Postsurgical displacement of bone grafts can also be the cause of diplopia and restricted ocular motility. If suspected and confirmed with CT scan, the displaced bone graft or displaced segment of the orbit can be repositioned away from the ocular globe and extraocular muscles. Generally this adequately resolves the situation. Presurgical and postsurgical evaluation by an ophthalmologist is critical to the decisions made to resolve diplopia. Rarely is eye muscle surgery necessary to resolve the condition. Limitation of ocular movement is also rare. Entrapment of muscles in osteotomy defects is a possibility to consider when this occurs. Forced duction at the completion of the operation should eliminate this as a cause. When limitation of ocular movement occurs, it is more likely secondary to edema in the affected muscles. Another potential source of limitation of ocular movement postsurgery is the displacement of bone grafts or advancements of the lateral orbital rims, which may result in globe displacement or spasm of the extraocular muscles. Patience and observation for at least 6 months usually results in complete return of ocular movement. Superior Orbital Fissure Syndrome Swelling or inadvertent fracture patterns extending to the superior orbital fissure are not unheard of but are rare. At the completion of surgery if a fixed dilated pupil, lid ptosis, and ophthalmoplegia are detected, injury involving the constrictors of the iris should be suspected. Inadvertent fracture to the skull base during mobilization of the midface may result in involvement of the cranial nerves of the superior orbital fissure (III, IV, first division of V, and VI). Complete neurological and ophthalmological work ups including eye pressures and CT scans are mandatory to rule out other causes of the problem. Comparison evaluations with the presurgical ophthalmological and neurological findings are very useful. If direct impingement by bone fragments in the superior orbital fissure is observed, surgical decompression may be considered an option. Access to this area is difficult and identifying small segments of bone may be impossible. A major consideration is that surgery may actually worsen the situation. Another option is treatment with high

dose steroids to reduce edema and continued monitoring and observing the condition. These authors feel it most prudent to elect the nonsurgical course with administration of steroids and patience. When this rare complication occurs, it is very disheartening to patients and it requires encouragement and patience to allow it to resolve.28,29 Facial Nerve Injury When elevating a scalp flap, it is important to identify all layers of the scalp. It is critical to perform dissection of the forehead and face in a subperiosteal plane, and this will avoid direct damage to the facial nerve. The dissection of the flap over the temporalis muscle must be under the tempo-parietal fascia, which is the extension of the superficial muscular aponeurotic system of the face. This is the layer of tissue that contains the seventh nerve fibers. The best way to protect the nerve is to be in the correct plane during dissection. If there is a seventh nerve deficit after surgery, recovery is expected if the correct plane is dissected. If nerve severance is witnessed, immediate microneural repair probably results in the best chances of return of function. Injuries to the seventh nerve should be minimal with craniofacial surgery, providing that the dissection of the face is subperiosteal and dissection over the temporalis muscle is under the temperoparietal fascia and on the superficial layer of the deep temporal fascia. Neurosensory Disturbance Neurosensory disturbance is an expectation of craniofacial surgery, just as it is with orthognathic surgery. Forehead, cheeks, upper lip, and nose are the usual areas affected. Although the sensory nerves are not intentionally severed, the dissection and retraction are the most common reasons for neurosensory disturbance. Our group encourages early massage and tactile stimulation, which may have a positive effect on return of sensation. Over the long term, patients rarely acknowledge reduced feeling over these areas; and as far as the authors are aware, the neurosensory loss has never been the source of a functional problem. There appears to be a direct relationship between neurosensory return and age of the patient with younger ages favoring quicker and greater return of sensation. Sensory disturbance of the tongue with loss of taste or dysgeusia is a rare complication of mandibular osteotomies. When this occurs, it is of greater consequence to patients whose livelihoods depend on the sense of taste. Some patients also complain of speech difficulties resulting from loss of sensation and dysgeusia, not loss of movement. The extent of disability experienced by the patient should be used as the gauge to determine their candidacy for secondary nerve surgery. The success of secondary neural surgery is time dependent, and best results are seen when correction is undertaken before 6 months postsurgery. Olfactory disturbance is expected when craniofacial surgery involves the skull base, especially the cribriform plate of the ethmoid bone. The fine terminal threads of the first cranial nerve perforate through this structure to innovate the mucosa of the nose, and dissection in this area is necessary to provide adequate protection to the frontal lobes. Anosmia is an expected result of orbital translocation surgery when the skull base is involved. Surgical techniques have been developed to help spare olfactions during elective craniofacial surgery. This requires

CHAPTER 59  Principles of Craniofacial Surgery and the Management of Complications microscopical dissection and sparring of the branches of the olfactory nerve because it perforates the cribriform plate.8 Our experience is that rarely does the elective craniofacial surgery population complain of anosmia. This is unlike the craniofacial fracture or tumor populations in which the loss is more disturbing. Many factors are responsible for this including the age of the patients (the elective craniofacial population is younger, and they are likely able to accommodate better and recover neurologically) and the psychological difference between the populations. The elective craniofacial population is informed of the possibility of the loss before treatment and decides to proceed with surgery anyway. The trauma and tumor ablation populations have little or no choice. Additionally, the tumor or trauma population may have an incentive to exploit this sensory loss with ligation. Scarring and Incision Placement Initially an ear-to-ear linear incision was made for the coronal approach. The access is great and provided that the flap is adequately raised and relaxed the preauricular or postauricular extension is seldom necessary. Over time, these incisions heal well and are not visible, except if the patient experiences balding, and then it is usually only visible at the vertex of the head. For most men, this is not an issue. In children, however, the scars can stretch especially with growth and can be an issue requiring revision. Whether the scar is made with a scalpel or an electrocautery doesn’t seem to make a difference relative to scarring. Bipolar electrocautery use in the deep layer of the scalp is more sparing to hair follicles. The tension of closure is an issue that can contribute to scar widening. With adequate release of pericranium on both sides of the incision, the wound should be able to be closed primarily in two layers. Although some surgeons have found it necessary for skin grafting to assist with scalp closure, these authors have never found it to be necessary. The stealth incision was introduced as in improvement to coronal scar visibility. The incision breaks the linearity of the straight line coronal scar however the extra time to open and close the wound, and the additional blood loss are other considerations. The decision of which flap to use remains the surgeon’s preference. There is hardly ever a reason to include eyelid incisions in craniofacial surgical procedures today, including transconjunctival and direct inferior lid incisions. There are exceptions to this generalization, but they are rare. In most circumstances, adequate exposure of the orbital walls and floors can be obtained through the coronal approach with wide subperiosteal exposure of the midfacial skeleton. Excision of the tissue from the nasal dorsum and forehead remains controversial, especially with hypertelorism correction and eyebrow translocation. Excision with Z-plasty closure has given unsatisfactory results. Excisions with straight line closure are the most cosmetically acceptable; however, a linear scar always remains. On the nasal dorsum, the scar fades nicely; however, the forehead and nasion is where the scar remains visible. The decision to excise skin with hypertelorism correction must be left to the surgeon and the patient. Our group feels that it is wisest to delay skin excision for at least 6 months following orbital translocation surgery to allow for shrinkage to occur. Deciding if excessive tissue is more noticeable than a linear scar determines the need for further surgery.

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PITFALLS • Lack of teamwork within a MDT of health care providers can negatively affect the overall care and comprehensive management of patients. • Lack of attention to the details of establishing a diagnosis and developing a prioritized treatment plan can lead to poor outcomes. • Ignoring the basic principles of facial skeletal surgery can lead to a disappointing outcome. • Not recognizing the early signs or symptoms associated with postsurgical complications is a critical mistake.

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21. Saltz R, Sierra D, Feldman D, et al: Experimental and clinical applications of fibrin glue. Plast Reconstr Surg 88(6):1005–1015, 1991. 22. Ellis E, Zide MF: Surgical approaches to the facial skeleton, Baltimore, 1995, Williams & Wilkins. 23. Wolfe SA, Morrison G, Page LK, et al: The monobloc frontofacial advancement: do the pluses outweigh the minuses? Plast Reconstr Surg 91(6):977–989, 1993. 24. Politano N, Jaskolka M, Blakey GH, et al: The effect of preoperative recombinant erythropoietin on postoperative hematocrit level after orthognathic surgery. J Oral and Maxillofac Surg 70(11):625–630, 2012. 25. Choi WS, Irwin MG, Samman N: The effect of tranexamic acid on blood loss during orthognathic surgery: a randomized controlled trial. Int J Oral and Maxillofac Surg 67:125–133, 2009.

26. Turvey TA, Proffit WR, Phillips C: Biodegradable fixation for craniomaxillofacial surgery: a 10 year experience involving 761 operations in 745 patients. Int J Oral and Maxillofac Surg 40:244–249, 2011. 27. Goldstein JA, Paliga JT, Taylor JA, et al: Complications in 54 frontofacial distraction procedures in patients with syndromic craniosynostosis. J Craniofac Surg 26(1):124–128, 2015. 28. Brookes CD, Golden BA, Lawrence SD, et al: Unilateral mydriasis after maxillary osteotomy: a case series review of the literature. J Oral and Maxillofac Surg 73(6):1159–1168, 2015. 29. Warburton EA, Brookes CC, Golden BA, et al: Orbital apex disorders: a case series. Int J Oral and Maxillofac Surg pii:S0901-5027(15)01384-3, 2015.