Arthur J. Nam

Twenty-six-year experience treating frontal sinus fractures: a novel algorithm based on anatomical fracture pattern and failure of conventional techniques.

Background: Frontal sinus fracture treatment strategies lack statistical power. The authors propose statistically valid treatment protocols for frontal sinus fracture based on injury pattern, nasofrontal outflow tract injury, and complication(s). Methods: An institutional review board–approved retrospective review was conducted on frontal sinus fracture patients from 1979 to 2005. Fractures were categorized by location, displacement, comminution, and nasofrontal outflow tract injury. Demographic data, treatment, and complications were compiled. Results: One thousand ninety-seven frontal sinus fracture patients were identified; 87 died and 153 were excluded because of insufficient data, leaving a cohort of 857 patients. The most common injury was simultaneous displaced anteroposterior walls (38.4 percent). Nasofrontal outflow tract injury constituted the majority (70.7 percent), with 67 percent having a diagnosis of obstruction. Of the 857 patients, 504 (58.8 percent) underwent surgery, with a 10.4 percent complication rate; and 353 were observed, with a 3.1 percent complication rate. All complications except one involved nasofrontal outflow tract injury (98.5 percent). Nasofrontal outflow tract injuries with obstruction were best managed by obliteration or cranialization (complication rates: 9 and 10 percent, respectively). Fat obliteration and osteoneogenesis had the highest complication rates (22 and 42.9 percent, respectively). The authors’ treatment algorithm provides a receiver operating characteristic area under the curve of 0.8621. Conclusions: A frontal sinus fracture treatment algorithm is proposed and statistically validated. Nasofrontal outflow tract involvement with obstruction is best managed by obliteration or cranialization. Osteoneogenesis and fat obliteration are associated with unacceptable complication rates. Observation is safe when the nasofrontal outflow tract is intact.

An Anatomical Study of External Carotid Artery Vascular Territories in Face and Midface Flaps for Transplantation

Background: The technical success of facial composite tissue allotransplantation demands full understanding of superficial and deep perfusion for reliable microvascular transfer. Candidates with composite midface defects require an appreciation of the circulatory patterns to design a composite midface allotransplant. Methods: External carotid vascular territories were evaluated in 10 cadavers to determine the reliability of facial soft-tissue flaps based on a single vascular pedicle. The right common carotid artery was injected with red latex and the left was injected with blue latex. Dual perfusion was confirmed by purple, following two-color mixing. Vascular pedicles included the superficial temporal, transverse facial, and facial arteries. In five additional cadavers, the midface segment was isolated by Le Fort III osteotomy after two-color latex injection with inclusion of the internal maxillary vascular pedicle. Cadavers were imaged with three-dimensional computed tomographic reconstructions following latex injection to confirm perfusion patterns. Results: In soft-tissue facial flaps, unilateral carotid dominance was seen in the nasal dorsum and tip, confirming reliable supply by a single external carotid artery. In midface flaps, bilateral perfusion was seen in the maxilla. Ipsilateral perfusion was observed at the zygomaticomaxillary complex without any contralateral contribution. Conclusions: Dual soft-tissue perfusion was confirmed in most specimens at the nasal, central face, and maxilla. The inclusion of the maxilla in the design of a facial composite allotransplant demands bilateral vascular pedicles based on the internal maxillary arteries. The authors highlight a procurement strategy for design of such flaps.

Facial subunit composite tissue allografts in nonhuman primates: I. Technical and immunosuppressive requirements for prolonged graft survival.

Background: Widespread application of composite tissue allotransplantation has been impeded by risks of rejection and conventional immunosuppression. The authors have developed a nonhuman primate composite tissue allotransplantation model that demonstrated reliable and long-term success necessary to progress to preclinical studies. Methods: Composite facial subunits (e.g., skin, muscle, and bone) were transplanted between mismatched cynomolgus monkeys. Vascular supply was based on the common carotid artery and external and internal jugular veins. Facial allografts were heterotopically transplanted to the recipient’s lower abdomen with end-to-side anastomoses of the common carotid artery to the common femoral artery and of both the internal and external jugular veins to the common femoral vein. Animals received tacrolimus monotherapy. Grafts were inspected daily, submitted to biopsy regularly, and studied with magnetic resonance imaging. Results: Thirteen transplants were performed. Two grafts based on the common carotid artery and only the internal jugular vein failed within 3 to 5 days because of venous thrombosis not related to rejection. Subsequent transplants included anastomoses of both the internal and external jugular veins to the common femoral vein without thromboses. Immunosuppression consisted of tacrolimus monotherapy and was tolerated without complications. Long-term success was achieved with rejection-free graft survival (60 to 177 days). Conclusions: The authors have developed the first successful model of facial composite tissue allotransplantation in a nonhuman primate. Technical requirements include preservation of both internal and external jugular venous outflow. Tacrolimus monotherapy permitted prolonged rejection-free graft survival without early complications. This model provides a platform for further investigation of composite tissue allotransplantation tolerance and requirements for indefinite survival.

Frontobasal fractures: Anatomical classification and clinical significance

Background: Frontobasal injury is a classic craniomaxillofacial fracture affecting the anterior cranial base. No data exist regarding the degree of frontobasal injury and associated midfacial fractures. The authors propose a classification of frontobasal and midface fractures involving the cranial base based on cadaveric experiments and comprehensive clinical experience. Methods: An institutional review board–approved retrospective review was conducted on patients with frontobasal fractures from 1995 to 2005. Fractures were categorized by pattern, location, midfacial involvement (impure), and complications compiled. One hundred five cadaveric heads underwent blunt impact to the frontal bone and upper midface. Calvarial vault, cranial base, and midface fracture patterns were categorized. Results: Three frontobasal fracture patterns were identified. Isolated linear cranial base fractures constitute type I. Vertical-linear fractures of the skull vault (frontal bone) occur in combination with base fractures, representing type II (vault and base). Comminution of the frontolateral skull vault and orbital roof in association with a linear base fracture constitute type III. Two hundred ninety patients were identified with 49 complications (cerebrospinal fistula, 24; and infectious 25). Type III (n = 159) had the highest complication rate (impure, 29 percent; pure, 17 percent), followed by type II (impure, 19 percent; pure, 5 percent). There is essentially no extension of midface fractures to the cranial vault. Conclusions: Frontobasal fractures have three unique and reproducible patterns based on vector, location, and force. This new classification scheme, paired with known patterns of midfacial injuries, assists in fully understanding frontofaciobasal injury and its complications. Overwhelmingly, impure type II and any type III fractures are associated with a high rate of complications and must be carefully managed.

Critical computed tomographic diagnostic criteria for frontal sinus fractures

PURPOSE Diagnosis and treatment of frontal sinus fractures (FSFs) have progressed over the previous 30 years. Despite advances in computed tomography, there is no current diagnostic uniformity with regard to classification and treatment. We developed a statistically valid treatment protocol for FSFs based on injury pattern, nasofrontal outflow tract (NFOT) injury, and complication(s). These data outlined predictable injury patterns based on specific computed tomographic findings critical to the diagnosis and ultimate treatment of this potentially fatal injury. MATERIALS AND METHODS A retrospective review was conducted on patients with FSF from 1979 to 2005 under institutional review board approval. All computed tomographic scans were reviewed by the authors and fractures categorized by location, displacement, comminution, and degree of NFOT injury. RESULTS One thousand ninety-seven patients with FSF were identified, 87 expired and 153 had inadequate data, leaving a group of 857 patients. Simultaneous displacement of anterior-posterior tables constituted the largest group (38.4%). NFOT injury occurred in most patients (70.7%) and was strongly associated with anterior (92%) and posterior (88%) table involvement (comminuted 98%). Sixty-seven percent of patients with NFOT injury had obstruction. Five hundred four patients (59.6%) had surgery with 10.4% complications and 353 patients were observed with 3.1% complications. All but 1 patient with complications had NFOT injury (98.5%). CONCLUSIONS Predictable patterns of injury based on specific computed tomographic data play a pivotal role in classification and surgical management of potentially fatal frontal sinus injuries. Radiologic diagnosis of NFOT injury in FSFs, particularly obstruction, plays a decisive role in surgical planning.

Prolonged Survival of Composite Facial Allografts in Non-Human Primates Associated With Posttransplant Lymphoproliferative Disorder

Background. Composite tissue allotransplantation may have different immunosuppressive requirements and manifest different complications compared with solid organ transplantation. We developed a non-human primate facial composite tissue allotransplantation model to investigate strategies to achieve prolonged graft survival and immunologic responses unique to these allografts. Methods. Composite facial subunits consisting of skin, muscle, and bone were heterotopically transplanted to mixed lymphocyte reaction-mismatched Cynomolgus macaques. Tacrolimus monotherapy was administered via continuous intravenous infusion for 28 days then tapered to daily intramuscular doses. Results. Five of the six animals treated with tacrolimus monotherapy demonstrated rejection-free graft survival up to 177 days (mean, 113 days). All animals with prolonged graft survival developed posttransplant lymphoproliferative disorders (PTLD). Three animals converted to rapamycin after 28 days of rejection of their allografts, but did not develop PTLD. Genotypic analysis of PTLD tumors demonstrated donor origin in three of the five analyzed by short-tandem repeats. Sustained alloantibodies were detected in rejecting grafts and absent in nonrejecting grafts. Conclusions. Tacrolimus monotherapy provided prolonged rejection-free survival of composite facial allografts in a non-human primate model but was associated with the development of a high frequency of donor-derived PTLD tumors. The transplantation of a large volume of vascularized bone marrow in composite tissue allografts may be a risk factor for PTLD development.

Abdominal ventral hernia repair with current biological prostheses: an experimental large animal model.

Biologic prostheses have emerged to address the limitations of synthetic materials for ventral hernia repairs; however, they lack experimental comparative data. Fifteen swine were randomly assigned to 1 of 3 bioprosthetic groups (DermaMatrix, AlloDerm, and Permacol) after creation of a full thickness ventral fascial defect. At 15 weeks, host incorporation, hernia recurrence, adhesion formation, neovascularization, inflammation, and biomechanical properties were assessed. No animals had hernia recurrence or eventration. DermaMatrix and Alloderm implants demonstrated more adhesions, greater inflammatory infiltration, and more longitudinal laxity, but near identical neovascularization and tensile strength to Permacol. We found that porcine acellular dermal products (Permacol) contain following essential properties of an ideal ventral hernia repair material: low inflammation, less elastin and stretch, lower adhesion rates and cost, and more contracture. The addition of lower cost xenogeneic acellular dermal products to the repertoire of available acellular dermal products demonstrates promise, but requires long-term clinical studies to verify advantages and efficacy.

Definitive Treatment of Persistent Frontal Sinus Infections : Elimination of Dead Space and Sinonasal Communication

Background: Frontal sinus injury involving nasofrontal outflow tract obstruction is routinely managed by obliteration or cranialization; however, a small percentage of patients develop persistent indolent infections despite routine measures. The authors discuss the course of persistent infection following frontal sinus fractures and propose a novel treatment that definitively obliterates and separates the nasofrontal outflow tract from the cranium in these patients. Methods: Seven consecutive patients with persistent indolent infections associated with frontal sinus fractures were identified and treated at the R Adams Cowley Shock Trauma Center and The Johns Hopkins Hospital from 2005 to 2008. Results: There were three women and four men, with an average age of 41 years. Injury resulted from motor vehicle crashes (n = 4), motorcycle crash (n = 1), fall (n = 1), and other accident (n = 1). All patients were previously treated with conventional techniques (average, 3.6 procedures and 11 years from initial injury) and prolonged antibiotic therapy without resolution of symptoms. Definitive treatment included radical débridement and obliteration with a free fibula flap in a single stage. All flaps survived and resulted in complete sinonasal separation and eradication of infection. There were no donor-site or frontal sinus complications. Conclusions: Radical débridement, meticulous removal of the tenacious sinus mucosa, and reconstruction with a free fibular flap in a single stage is a superb choice for eliminating persistent infectious complications associated with frontal sinus fractures in patients who have failed conventional management. The fibular flap provides a secure horizontal buttress, seals the nasofrontal outflow tract with vascularized muscle, and obliterates dead space.

Classification of mandible defects and algorithm for microvascular reconstruction

Background: Composite mandibular tissue loss results in significant functional impairment and cosmetic deformity. This study classifies patterns of mandibular composite tissue loss and describes a microvascular treatment algorithm. Methods: A retrospective review of microvascular composite mandibular reconstruction from July of 2005 to April of 2013 by the senior surgeon at the R Adams Cowley Shock Trauma Center and at The Johns Hopkins Hospital yielded 24 patients with a mean follow-up of 17.9 months. Causes of composite mandibular defects included tumors, osteoradionecrosis, trauma, infection, and congenital deformity. Patients with composite tissue loss were classified according to missing subunits. Results: A treatment algorithm based on composite mandibular defects and microvascular reconstruction was developed and used to treat 24 patients. A type 1 defect is a unilateral dentoalveolar defect not crossing the midline and not extending into the angle of the mandible. A type 2 defect is a unilateral defect extending beyond the angle. A type 3 defect is a bilateral defect not involving the angles. A type 4 defect is a bilateral defect with extension into at least one angle. Type 2 defects were the predominant group. Patients had microvascular reconstruction using either fibula flaps (n = 19) or iliac crest flaps (n = 5). Complications included infection, partial necrosis, plate fracture, dehiscence, and microvascular thrombosis. Conclusion: This novel classification system and treatment algorithm allows for a consistent and reliable method of addressing composite mandibular defects and focuses on recipient vasculature and donor free flap characteristics. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Treatment Outcomes following Traumatic Optic Neuropathy.

Background: Traumatic optic neuropathy is characterized by sudden loss of vision following facial trauma leading to variable visual deficits. The purpose of this study was to evaluate recent institutional trends in the treatment of traumatic optic neuropathy, evaluate the outcomes of different treatment strategies, and identify factors associated with improved vision. Methods: Institutional review board approval was obtained to retrospectively review patients diagnosed with traumatic optic neuropathy at a high-volume trauma center from 2004 to 2012. Pretreatment and posttreatment visual acuity was compared using quantitative analysis of standard ophthalmologic conversion. Results: A total of 109 patients met inclusion criteria (74.3 percent male patients), with a mean age of 38.0 ± 17.5 years (range, 8 to 82 years). Management of traumatic optic neuropathy involved intravenous corticosteroids alone in 8.3 percent of patients (n = 9), 56.9 percent (n = 62) underwent observation, 28.4 percent (n = 31) had surgical intervention, and 6.4 percent (n = 7) underwent surgery and corticosteroid administration. Only 19.3 percent of patients returned for follow-up. Vision improved in 47.6 percent of patients, with a mean follow-up of 12.9 weeks. Patients younger than 50 years had a trend toward higher rates of visual improvement, 60 percent versus 16.7 percent (p = 0.15). Conclusions: The majority of traumatic optic neuropathy patients are unlikely to return for a follow-up examination. Optic nerve decompression has fallen out of favor in the authors’ institution, and observation is the most common management strategy. Outcomes following corticosteroid administration and observation are comparable. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.