Nicholas T. Iliff

Mechanisms of Global Support and Posttraumatic Enophthalmos: I. The Anatomy of the Ligament Sling and Its Relation to Intramuscular Cone Orbital Fat

The mechanisms of posttraumatic enophthalmos were evaluated to determine the interrelation between fat and ligaments in globe support. Anatomic studies demonstrate that the ligaments form an essential “sling” framework for the globe but are alone insufficient to maintain the globes full forward position. Removal of extramuscular fat in cadavers and in patients undergoing blepharoplasty did not significantly change globe position. Loss of intramuscular cone fat (atrophy or displacement) in cadavers and patients produced enophthalmos. Fat atrophy is not a prominent feature in most patients with posttraumatic enophthalmos. Some loss of intramuscular cone fat from displacement outside the muscle cone is frequently present. The principal mechanism, however, of posttraumatic enophthalmos involves a displacement and change in the shape of orbital soft tissue. Loss of bone and ligament support permits posterior displacement and a reshaping of orbital soft tissue under the influence of gravity and the remodeling forces of fibrous scar contracture. The shape of the retrobulbar orbital contents changes from a modified cone to a sphere, and the globe sinks backward and downward. Given that the volume of orbital soft tissue is constant following trauma, procedures to restore the shape and position of the orbital soft tissue by mobilization and bone reconstruction will correct or significantly improve enophthalmos.

Use of Medpor porous polyethylene implants in 140 patients with facial fractures.

Use of alloplastic materials in facial bone reconstruction is still controversial. Medpor porous polyethylene is a relatively new implant material that is well suited for this purpose and has a number of advantages over other alloplasts. It is a pure polyethylene with a unique manufacturing process and pore size. Technically, it is easy to work with; it can be carved, contoured, adapted, and fixated to obtain a precise three-dimensional construct. Physically, it is a pure, biocompatible, strong substance that does not resorb or degenerate. It demonstrates long-term stability, high tensile strength, resistance to stress and fatigue, and a virtual lack of surrounding soft-tissue reaction. Rapid tissue ingrowth occurs into the pores. Extensive vascular ingrowth creates the potential to transport cellular products that fight infection deep into the implant. The implant was used in 140 patients from June 1988 to August 1991 to treat acute orbitozygomatic injuries (71), acute Le Fort injuries (24), delayed orbitozygomatic injuries (33), and delayed onlay augmentation (12). In this series, there was 1 instance of implant infection requiring removal, and no implant migration, or exposure.

blindness after Reduction of Facial Fractures

&NA; Blindness in patients suffering maxillofacial trauma is usually caused by optic nerve or optic canal injuries. It is, however, an uncommon complication of facial trauma, with a reported incidence of only 2 to 5 percent.1–6 Blindness may also follow surgical repair of facial fractures. Many mechanisms, such as intraoperative direct nerve injury,7 retinal arteriolar occlusion associated with orbital edema,8–11 or delayed presentation of indirect optic nerve injury sustained at the time of the initial trauma,12 have been implicated in causing this blindness. In this article, four cases of visual loss after surgical repair of facial trauma are reported. In a review of the University of Maryland Shock Trauma experience with facial trauma over 11 years, we discovered that 2987 of the 29,474 admitted patients (10.1 percent) sustained facial fractures, and that 1338 of these fractures (44.8 percent) involved one or both of the orbits. One thousand two hundred forty of these patients underwent operative repair of their facial fractures. Three patients experienced postoperative complications that resulted in blindness, a total incidence of only 0.242 percent. Postoperative ophthalmic complications seem to be primarily mediated by indirect injury to the optic nerve and its surrounding structures. The most frequent cause of postoperative visual loss is an increase in intraorbital pressure in the optic canal. When our data were added to the summarized cases, blindness was attributable to intraorbital hemorrhage in 13 of 27 cases (48 percent). In addition, 5 cases in our review attribute the visual loss to unspecified mechanisms of increased intraorbital pressure, bringing the total cases of visual loss caused by intraorbital pressure or hemorrhage to 18 of 27 cases, or 67 percent. Within the restricted confines of the optic canal, even small changes in pressure potentially may cause ischemic optic nerve injury. (Plast. Reconstr. Surg. 102: 1821, 1998.)

Subunit principles in midface fractures: the importance of sagittal buttresses, soft-tissue reductions, and sequencing treatment of segmental fractures.

The patterns of midface fractures were related to postoperative computed tomography scans and clinical results to assess the value of ordering fracture assembly in success of treatment methods. A total of 550 midface fractures were studied for their midface components and the presence of fractures in the adjacent frontal bone or mandible. Preoperative and postoperative computed tomography scans were analyzed to generate recommendations regarding exposure and postoperative stability related to fracture pattern and treatment sequence, both within the midface alone and when combined with frontal bone and mandibular fractures. Large segment (Le Fort I, II, and III) fractures were seen in 68 patients (12 percent); more comminuted midface fracture combinations were seen in 93 patients (17 percent). Midface and mandibular fractures were seen in 166 patients (30 percent). Midface, mandible, and nasoethmoid fractures were seen in 38 patients (7 percent). Frontal bone and midface fractures were seen in 131 patients (24 percent). Split-palate fractures accompanied 8 percent of midface fractures. Frontal bone, midface, and mandibular fractures were seen in 54 patients (10 percent). The midface, because of weak bone structure and comminuted fracture pattern, must therefore be considered a dependent, less stable structure. Its injuries more commonly occur with fractures of the frontal bone or mandible (two-thirds of cases) and, more often than not (>60 percent), are comminuted. Comminuted and pan-facial (multiple area) fractures deserve individualized consideration regarding the length of intermaxillary immobilization. Examples of common errors are described from this patient experience.

Understanding the origin of visual percepts elicited by electrical stimulation of the human retina

Abstract · Background: The success of a retinal prosthesis for patients with outer retinal degeneration (ORD) depends on the ability to electrically stimulate retinal cells other than photoreceptors. Experiments were undertaken in human volunteers to ascertain whether electrical stimulation of cells other than photoreceptors will result in the perception of light. · Methods: In two subjects, two areas of laser damage (argon green and krypton red) were created in an eye scheduled for exenteration due to recurrent cancer near the eye. In the operating room prior to exenteration, under local anesthesia, a hand-held stimulating device was inserted via the pars plana and positioned over the damaged areas and normal retina. Subjects’ psychophysical responses to electrical stimulation were recorded. · Results: In both subjects, electrical stimulation produced the following perceptions. Normal retina: dark oval (subject 1), dark half-moon (subject 2); krypton red laser-treated retina: small, white light (both subjects); argon green laser-treated retina: thin thread (subject 1), thin hook (subject 2). Histologic evaluation of the krypton red-treated retina showed damage confined to the outer retinal layers, while the argon green-treated area evinced damage to both the outer and the inner nuclear layers · Conclusion: The perception produced by electrical stimulation was dependent on the retinal cells present. Electrical stimulation of the krypton red-ablated area best simulated the electrically elicited visual perceptions of our blind, ORD patients, suggesting that the site of stimulation in blind patients is the inner retinal neurons.

Traumatic optic neuropathy: a review of 61 patients

The outcome of traumatic optic neuropathy was evaluated following penetrating and blunt injuries to assess the effect of treatment options, including high‐dose steroids, surgical intervention, and observation alone. Factors that affected improvement in visual acuity were identified and quantified. Sixty‐one consecutive, nonrandomized patients presenting with visual loss after facial trauma between 1984 and 1996 were assessed for outcome. Pretreatment and posttreatment visual acuities were compared using a standard ophthalmologic conversion from the values of no light perception, light perception, hand motion, finger counting, and 20/800 down to 20/15 to a logarithm of the minimum angle of resolution (log MAR). The percentage of patients showing visual improvement and the degree of improvement were calculated for each patient group and treatment method. Measurements of visual acuity are in log MAR units ± standard error of the mean. Patients who sustained penetrating facial trauma (n = 21) had worse outcomes than patients with blunt trauma (n = 40). Improvement in visual acuity after treatment was seen in 19 percent of patients with penetrating trauma compared with 45 percent of patients with blunt trauma (p < 0.05). Furthermore, patients with penetrating trauma improved less than those with blunt trauma, with a mean improvement of 0.4 ± 0.23 log MAR compared with 1.1 ± 0.24 in blunt‐trauma patients (p = 0.03). The patients with blunt trauma underwent further study. There was no significant difference in improvement of visual acuity in patients treated with surgical versus nonsurgical methods; however, 83 percent of patients without orbital fractures had improvement compared with 38 percent of patients with orbital fractures (p < 0.05). The mean improvement in patients without orbital fractures was 1.8 ± 0.65 log MAR compared with 0.95 ± 0.26 in patients with orbital fractures (p = 0.1). Twenty‐seven percent of patients who had no light perception on presentation experienced improvement in visual acuity after treatment compared with 100 percent of patients who had light perception on admission (p < 0.05). The mean improvement in patients who were initially without light perception was 0.85 ± 0.29 log MAR compared with 1.77 ± 0.35 in patients who had light perception (p < 0.05). There were no significant differences in improvement of visual acuity when analyzing the effect of patient age and timing of surgery. Patients who sustain penetrating trauma have a worse prognosis than those with blunt trauma. The presence of no light perception and an orbital fracture are poor prognostic factors in visual loss following blunt facial trauma. It seems that clinical judgment on indication and timing of surgery, and not absolute criteria, should be used in the management of traumatic optic neuropathy. (Plast. Reconstr. Surg. 107: 1655, 2001.)

Total face, double jaw, and tongue transplantation: An evolutionary concept

Background: The central face high-energy avulsive injury has been frequently encountered and predictably managed at the R Adams Cowley Shock Trauma Center. However, despite significant surgical advances and multiple surgical procedures, the ultimate outcome continues to reveal an inanimate, insensate, and suboptimal aesthetic result. Methods: To effectively address this challenging deformity, a comprehensive multidisciplinary approach was devised. The strategy involved the foundation of a basic science laboratory, the cultivation of a supportive institutional clinical environment, the innovative application of technologies, cadaveric simulations, a real-time clinical rehearsal, and an informed and willing recipient who had the characteristic deformity. Results: After institutional review board and organ procurement organization approval, a total face, double jaw, and tongue transplantation was performed on a 37-year-old man with a central face high-energy avulsive ballistic injury. Conclusions: This facial transplant represents the most comprehensive transplant performed to date. Through a systematic approach and clinical adherence to fundamental principles of aesthetic surgery, craniofacial surgery, and microsurgery and the innovative application of technologies, restoration of human appearance and function for individuals with a devastating composite disfigurement is now a reality. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Single eyelid incision for exposure of the zygomatic bone and orbital reconstruction

Experience with a single lower eyelid incision with mobilization of the lateral canthus is described for exposure of the zygoma, lower and lateral orbit, and zygomaticofrontal suture. The incision may be either subciliary with a skin-muscle flap or transconjunctival. Both require mobilization of the canthus. Reattachment of the canthus is not required in acute zygomatic fracture treatment but is preferred for secondary orbital reconstruction or in patients in whom a simultaneous coronal incision is employed. The approaches described reduce cutaneous scarring and provide generous exposure of the lower and lateral orbit. Predictable and improved aesthetic results are routinely achieved.

Mechanisms of extraocular muscle injury in orbital fractures.

The gross and microscopic events that occur after orbital blowout fractures were evaluated to assess the mechanisms of diplopia and muscle injury. Intramuscular and intraorbital pressures were evaluated in experimental animals, in cadavers, and at the time of orbital fracture explorations for repair of orbital fractures in humans. Histologic and circulatory changes, muscle pressure recordings, and operative observations were evaluated. Creation of a compartment syndrome was evaluated to include a histologic evaluation of the orbital fibrous sheath network for the extraocular muscles and the intramuscular vasculature. These experiments and observations do not support the role of a compartment syndrome in ocular motility disturbances because (1) intramuscular pressures were subcritical in both humans and animals; (2) no limiting fascial compartment could be demonstrated; and (3) microangiograms and histologic evaluations did not confirm areas of compartmental ischemic necrosis. Muscle contusion, scarring within and around the orbital fibrous sheath network, nerve contusion, and incarceration within fractures remain the probable causes of diplopia, with the most likely explanations being muscle contusion and fibrosis or incarceration involving the muscular fascial network.

Management of blow-out fractures of the orbital floor. II. Early repair for selected injuries

Abstract The management of orbital fractures has long been controversial. In some cases, surgical repair is required, and early repair is more successful than secondary reconstruction. In other cases, slow resolution of diplopia over four to six months obviates surgery. In an editorial and two separate articles, the authors elucidate indications for and results of the early vs. late surgical repair of orbital blow-out fractures.