Orbital Asymmetry Research Articles

Spring-Assisted Cranioplasty in Unicoronal Synostosis: Analysis of Outcomes

Background: Spring-assisted cranioplasty and successful long-term outcomes for sagittal synostosis has been well described in recent literature. However, there is a paucity of data regarding the application of springs to unicoronal synostosis. Unicoronal synostosis (UCS) presents unique challenges in its causation of skull base scoliosis and orbital asymmetry. Many surgeons feel that the fronto-orbital advancement and vault remodeling is the most effective and reliable strategy to counteract these changes. Here we present our experience and outcomes with spring cranioplasty for unicoronal synostosis. Materials and methods: A retrospective review of non-syndromic unicoronal synostosis patients undergoing spring-assisted cranioplasty was performed. Preoperative and postoperative intracranial volume (ICV), orbital volume (OV), orbital height (OH), orbital width (OW), midface twist (MFT), and skull-base twist (SBT) were measured from DICOM CT data. Analysis was performed with Materialize software (Leuven, Belgium). Paired t-tests were performed using Excel. Results: Ten patients (5 females, 5 males) had springs placed at 100.1 days (avg). Average ICV: preop: 608.2 ± 101.4 cc, postop: 995.2 ± 166.1 cc. Differences in orbital volume and height in the preop affected orbit versus non-affected orbit was significant ( P = .01, P ≤ .001 respectively) whereas no significant difference between the two sides postoperatively was observed ( P = .19, P = .58 respectively). Average preop MFT was 81.1 ± 2° and postop was 87.6 ± 2.6° and preop SBT was 171.9 ± 2.7° and postop was 177.6 ± 2.6°; both showing significant improvement after spring cranioplasty (both P ≤ .001). Conclusion: Our experience and early outcomes with spring cranioplasty for UCS demonstrates that when used in younger patients (<5 months) cranial springs can be a safe and effective strategy to minimize skull base scoliosis, facial scoliosis, and orbital asymmetry, as well as increase intracranial volume. Although long-term data needs to be assessed, we are optimistic that early correction of cranial base scoliosis will translate to stable results as patients reach dentoskeletal maturity.

Understanding the heterogenicity of unicoronal synostosis – A morphometric analysis of cases compared to controls

BackgroundPreoperative severity of unicoronal synostosis varies greatly and involves the frontal bone, skull base and orbits. Degree of deformity affects long-term morphological and functional outcome after surgery. The aim of this study was to describe the morphological heterogenicity and investigate its relation to patient-specific factors. Materials and methodsIn this retrospective cohort study, non-syndromic unicoronal synostosis patients treated between 2006-2022 at Necker Hospital, France, or Uppsala University Hospital, Sweden, were included and matched to controls. Severity of skull base, orbital and posterior skull asymmetry, degree of anterior plagiocephaly and Harlequin deformity, lateralization, head circumference, age, timing of metopic fusion and fusion of peri-pterionic sutures were investigated. ResultsNinety-five patients and ninety-three controls were included. Skull base asymmetry was linearly related to orbital asymmetry (p < 0.001), correlated with earlier CT scans (p = 0.004), anterior (p < 0.001) and posterior (p = 0.03) plagiocephaly. Posterior plagiocephaly was more common in patients (31%) compared with controls (5%) (p < 0.001). A patent metopic suture above nine months of age was associated with severe Harlequin deformity (p = 0.04) and lower head circumference when fused (p = 0.03). Fronto-sphenoidal suture fusion was associated with later CT scans (p < 0.001) and less skull base asymmetry (p = 0.002). Spheno-parietal fusion was correlated with decreased skull base asymmetry. Right lateralization was more common in females. ConclusionHeterogenicity of unicoronal synostosis seems to be predominantly explained by variability in skull base morphology. Peri-pterionic fusions might limit deformity.

Comparative study of orbital volumes according to multispiral computed tomography data

BACKGROUND: It is believed that accurate reconstruction of the correct anatomy of the orbital bony walls, restoration of symmetry and volume are necessary for a favorable functional prognosis and elimination of an aesthetic defect. The main problem when estimating orbital volume is its complex anatomy. Scientists use various methods to determine orbital volume, and in reviews comparing various methods for calculating orbital volumes, there is no data on which orbital volumetric method is the most accurate, since each of them has both advantages and disadvantages. AIM: The aim of this study is the analysis and the comparison of orbital volumes according to multispiral computed tomography data of healthy patients without bone-traumatic changes of orbital walls. MATERIALS AND METHODS: To measure the volume of orbits, 50 random patients were selected who were examined in the radiology department No. 2 of the University Clinical Hospital No. 1 of the Sechenov University from 2023 to 2024 and who underwent multispiral computed tomography of the facial skeleton for indications unrelated to orbital conditions. Computed tomography data from 25 women and 25 men of different ages (from 18 to 85 years old) were analyzed. A total of 8 groups were formed depending on gender and age: group 1 — women 18–25 years old, group 2 — men 18–25 years old, group 3 — women 26–35 years old, group 4 — men 26–35 years old, group 5 — women 36–50 years old, group 6 — men 36–50 years old, group 7 — women 51 and older, group 8 — men 51 and older. Multispiral computed tomography of the facial skeleton was performed using the Aquilion One 640 CT scanner (Japan) with 0.5 slice thickness in bone and soft tissue windows, to be able to calculate orbital volumes at the workstation, all bone contours of the orbits were marked on each axial slice, starting from the upper wall to the bottom of the orbit with a representation of the orbital volumes in ml. RESULTS: The difference in the volumes of the right and left orbits of 0.5 ml or more was detected in 5 women out of 25 cases, among men the difference was present in 12 cases out of 25; a difference in volumes of more than 1 ml was noted in 1 woman and 2 men; a difference of more than 1.5 ml was not observed in any study group. The orbital asymmetry coefficient in women ranged from 0 ml to 1.21 ml, in men — from 0.08 ml to 1.19 ml, in women, the average volume of both orbits is less than in men. It was also detected that the volume of orbits increases with age, both in men and women. CONCLUSIONS: Considering that the majority of patients had differences in orbital volumes of up to 1.0 ml, we agree with studies that indicate the possibility of using a healthy contralateral orbit as a guideline when planning reconstructive surgery. However, for planning surgical treatment, it is recommended to use manual contouring, as this allows the most accurate reproducibility of the bone boundaries of the orbit, although it requires more time than semi- and automatic segmentation. Also, the advantages of the used method for calculating the volumes of orbits in this study include reproducibility on any workstation from different manufacturers, since the method is carried out on a standard tomograph workstation and does not require any additional software.

The relationship between eye canting and vertical craniofacial skeletal asymmetry in adult patients with dento-maxillofacial deformities

BackgroundWhether eye canting in patients with asymmetric dento-maxillofacial deformities is the result of anatomical asymmetry or a compensatory head position remains controversial. ObjectiveThis cross-sectional study aims to verify whether eye canting is correlated with craniofacial skeletal asymmetry. Methods & materialsThis study was performed by measuring the computed tomographic scans of 223 patients with dento-maxillofacial deformities in Mimics 21.0 software. First grouping was determined based on the intersection angle between the line passing through bilateral lateral canthus point and Frankfurt horizontal plane, and final grouping was based on measurements of the pregroups. ResultsThe patients were finally categorized into three groups: symmetry group (n = 163), asymmetry subgroups 1 (n = 33) and asymmetry subgroups 2 (n = 27). The results of multiple linear regression and comparisons among groups suggests the presence of orbital skeletal asymmetry in patients with eye canting and the eye canting is partly increment dependent of orbital skeletal asymmetry when using bilateral ears as the reference. The result also reveals that there is a greater angle between the line through bilateral ocular landmarks and the line through the bilateral ear landmarks in patients with ocular canting compared to patient without eye canting. ConclusionPatients with asymmetric dento-maxillofacial deformities and with eye canting have vertical asymmetry of the orbital and cranial skeletal landmarks. These symmetry differences between the eyes and ears may affect the overall craniofacial symmetry after orthognathic surgery

Impact of One-Piece Fronto-Orbital Distraction Osteogenesis on Orbital Morphology and Strabismus Development in Unilateral Craniosynostosis.

Unicoronal craniosynostosis (UCS) is associated with orbital dysmorphologies that underlie ophthalmologic dysfunctions, such as strabismus. This study aimed to assess orbital dysmorphology in patients with UCS and how it changes after fronto-orbital distraction osteogenesis (FODO), and to analyze the features of new-onset strabismus. A retrospective analysis was conducted on 19 patients with UCS who underwent FODO between May of 2008 and November of 2020. Ophthalmologic records and computed tomographic scans were reviewed. Seven parameters, including width, height, volume, and four-direction orbital angles were evaluated in patients with UCS and compared with those of age-matched control subjects. The superolateral angle and vertical angle of the ipsilateral orbit and the superomedial angle (SMA) of the contralateral orbit were more obtuse than those of the controls. Following FODO, the ipsilateral superolateral angle was decreased from 69.2 ± 5.4 degrees to 59.1 ± 4.2 degrees ( P = 0.001), and the contralateral SMA was decreased from 64.8 ± 5.8 degrees to 60.2 ± 6.0 degrees ( P = 0.003). Four of the 17 patients without strabismus in the preoperative period developed strabismus, and the horizontal type was the most common. Logistic regression analysis demonstrated a significant association between new-onset strabismus and SMA difference between both orbits (OR, 1.39; P = 0.041). Orbital dysmorphology in the UCS is bilateral, and the orbital roofs are dysmorphic. The bilateral orbital roofs are lifted toward the fused coronal suture and can be improved after FODO. Horizontal strabismus, such as esotropia and exotropia, is common after FODO, and superomedial orbital roof asymmetry may play a role in its development. Therapeutic, IV.

Persistent discrepancies in orbital morphology after surgical treatment of unicoronal craniosynostosis: a critical image-based analysis.

Unicoronal craniosynostosis (UCS) is characterized by complex orbital deformity and is typically treated by asymmetrical fronto-orbital remodeling (FOR) during the 1st year of life. The aim of this study was to elucidate to what extent orbital morphology is corrected by surgical treatment. The extent to which orbital morphology was corrected by surgical treatment was tested by analysis of differences in volume and shape between synostotic, nonsynostotic, and control orbits at two time points. In total, 147 orbits were analyzed from patient CT images obtained preoperatively (mean age 9.3 months), at follow-up (mean age 3.0 years), and in matched controls. Semiautomatic segmentation software was used to determine orbital volume. For analysis of orbital shape and asymmetry, geometrical models, signed distance maps, principal modes of variation, and three objective parameters (mean absolute distance, Hausdorff distance, and dice similarity coefficient) were generated by statistical shape modeling. Orbital volumes on both the synostotic and nonsynostotic sides were significantly smaller at follow-up than volumes in controls and significantly smaller both preoperatively and at follow-up than orbital volumes on the nonsynostotic side. Significant differences in shape were identified globally and locally, both preoperatively and at 3 years of age. Compared with controls, deviations were mostly found on the synostotic side at both time points. Asymmetry between synostotic and nonsynostotic sides was significantly decreased at follow-up, but not compared with the inherent asymmetry of controls. On a group level, the preoperative synostotic orbit was mainly expanded in the anterosuperior and anteroinferior regions and smallest on the temporal side. At follow-up, the mean synostotic orbit was still larger superiorly but also expanded in the anteroinferior temporal region. Overall, the morphology of nonsynostotic orbits was more similar to that of controls than to synostotic orbits. However, the individual variation in orbital shape was greatest for nonsynostotic orbits at follow-up. In this study, the authors presented what is, to their knowledge, the first objective automatic 3D bony evaluation of orbital shape in UCS, defining in greater detail than has been done previously how synostotic orbits differ from nonsynostotic and control orbits, and how orbital shape changes from 9.3 months of age preoperatively to 3 years of age at the postoperative follow-up. Despite surgical treatment, both local and global deviations in shape persist. These findings may have implications for future directions in the development of surgical treatment. Future studies connecting orbital morphology to ophthalmic disorders, aesthetics, and genetics could provide further insight to enable better outcomes in UCS.

The Use of the Three-Dimensional Printed Polyether Ether Ketone Implant in Secondary Craniosynostosis Revision.

Skull deformities may be seen in patients years after craniosynostosis correction. These deformities cause psychosocial distress in affected patients. In this series, the authors describe the use of patient specific polyether ether ketone (PEEK) implants for correction of skull deformities after cranial vault remodeling for craniosynostosis. A chart review was conducted for 3 revision procedures performed by 1 plastic surgeon in collaboration with 1 neurosurgeon, both affiliated with Northwell Health. Preoperative computed tomography scans were used to design three-dimensional (3D) printed PEEK implants manufactured by KLS Martin. Implants were used to correct frontal and orbital asymmetry and skull deformities in each patient. Outcomes were assessed at 1 week, 1 month, and 3 months post-operation. Two males and 1 female, ages 13, 17, and 19, underwent revision cranioplasty or orbital rim reconstruction using a custom, single piece 3D printed PEEK implant. All 3 patients underwent cranial vault remodeling in infancy; 1 was treated for coronal craniosynostosis and 2 were treated for metopic craniosynostosis. Revision cranioplasty operative times were 90, 105, and 147 minutes, with estimated blood loss of 45 mL, 75 mL, and 150 mL, respectively. One patient went home on post op day 1 and 2 patients went home on post op day 2. All patients had an immediate improvement in structural integrity and cranial contour, and all patients were pleased with their aesthetic results. Custom 3D printed PEEK implants offer a single piece solution in revision cranioplasty surgery to correct skull deformities after cranial vault remodeling for craniosynostosis.

Spontaneous Orbital Hematoma: A Rare Complication of Vaginal Delivery

A 34-year-old healthy woman, gesta2 para1, complains, after an uncomplicated, term, vaginal delivery, of left ocular pressure associated with double vision. On physical examination, an orbital asymmetry with left eye proptosis and inferior deviation was observed. Ophthalmological examination revealed a left vertical diplopia with normal visual acuity (10/10, bilaterally).

Assessment of the Orbital and Auricular Asymmetry in Italian and Sudanese Children: A Three-Dimensional Study

The evaluation of the symmetry of orbital and ear soft tissues is important for aesthetic and reconstructive surgery. However, little information is available for these facial regions, especially in children. We analyzed the orbital and auricular symmetry in 418 Italian and 206 Sudanese subadult males divided into three age groups (8–11, 12–15, and 16–19 years old). Orbital and auricular height and width were measured for calculating fluctuating and directional asymmetry indices. Differences in asymmetry indices according to ethnicity and age group were assessed through the two-way ANOVA test (p &lt; 0.01), while differences in the prevalence of right or left asymmetry according to ethnicity were assessed through the chi-square test. On average, directional asymmetry indices ranged from −2.1% to 1.1%, while fluctuating asymmetry indices ranged between 2.9% and 5.4%, corresponding to a small effect size and to 1.06–2.34 mm actual dimensions. Sudanese subjects showed a greater asymmetry for all the indices except for the fluctuating asymmetry of orbital height (p &lt; 0.01). The directional asymmetry of auricular width increased with age. A prevalent right-side asymmetry was found for all the orbital indices (p &lt; 0.001) in both populations, although significantly more prevalent in Sudanese individuals (over 83% for both measures), while auricular measures showed a prevalent left asymmetry exclusively in the Sudanese but with lower percentages. Aside from the limited effect size, the results proved the ethnic variability of asymmetry of orbital and auricle regions in children and suggest the need to collect more population data.

Orbital Volumetric Analysis in Patients With Unicoronal Craniosynostosis: A Comparison Between Distraction Osteogenesis and Fronto-Orbital Advancement.

Unicoronal craniosynostosis is associated with orbital restriction and asymmetry. Surgical treatment aims to both correct the aesthetic deformity and prevent the development of ocular dysfunction. We used orbital quadrant and hemispheric volumetric analysis to assess orbital restriction and compare the effectiveness of distraction osteogenesis with anterior rotational cranial flap (DO) and bilateral fronto-orbital advancement and cranial vault remodeling (FOAR) with respect to the correction of orbital restriction in patients with unicoronal craniosynostosis. A retrospective review of all patients with a diagnosis of unicoronal craniosynostosis and treated with either DO or FOAR from 2000 to 2019 was performed. Preoperative and postoperative total orbital volumes, as well as quadrant and hemispheric volume ratios, were calculated from 3-dimensional head computed tomography scans. Selected preoperative and postoperative orbital measurements, including the maxillary length of the orbit (MLO; zygomaticofrontal suture to the top of zygomatic arch) and the sphenoid length of the orbit (SLO; the top of sphenoid suture to the top of zygomatic arch), were also obtained. Data were available for 28 patients with unicoronal craniosynostosis. Mean preoperative total orbital volume was significantly smaller on the synostotic side compared with the nonsynostotic side (10.94 vs 12.20 cm3, P = 0.04). Preoperative MLO and SLO were significantly longer on the synostotic side compared with the nonsynostotic side (MLO: 20.26 vs 17.75 mm, P < 0.001; SLO: 26.91 vs 24.93 mm, P = 0.01). Distraction osteogenesis and FOAR produced significantly different changes in orbital quadrant and/or hemispheric volume ratios on the nonsynostotic side but not on the synostotic side. Before correction, patients with unicoronal craniosynostosis have significantly smaller total orbital volumes on the synostotic side compared with the nonsynostotic side and significantly greater MLO and SLO on the synostotic side compared with the nonsynostotic side. There is no significant difference between DO and FOAR with regard to correcting the observed orbital restriction in these patients.

Novel MYT1 variants expose the complexity of oculo-auriculo-vertebral spectrum genetic mechanisms.

Oculo-auriculo-vertebral spectrum (OAVS) is a developmental disorder characterized by anomalies mainly involving the structures derived from the first and second pharyngeal arches. The spectrum presents with heterogeneous clinical features and complex etiology with genetic factors not yet completely understood. To date, MYT1 is the most important gene unambiguously associated with the spectrum and with functional data confirmation. In this work, we aimed to identify new single nucleotide variants (SNVs) affecting MYT1 in a cohort of 73 Brazilian patients diagnosed with OAVS. In addition, we investigated copy number variations (CNVs) encompassing this gene or its cis-regulatory elements and compared the frequency of these events in patients versus a cohort of 455 Brazilian control individuals. A new SNV, predicted as likely deleterious, was identified in five unrelated patients with OAVS. All five patients presented hearing impairment and orbital asymmetry suggesting an association with the variant. CNVs near MYT1, located in its neighboring topologically associating domain (TAD), were found to be enriched in patients when compared to controls, indicating a possible involvement of this region with OAVS pathogenicity. Our findings highlight the genetic complexity of the spectrum that seems to involve more than one variant type and inheritance patterns.

Correlation between electronic and structural orders in 1T−TiSe2

The correlation between electronic and crystal structures of 1T-TiSe2 in the charge density wave (CDW) state is studied by x-ray diffraction. Three families of reflections are used to probe atomic displacements and the orbital asymmetry in Se. Two distinct onset temperatures are found, TCDW and a lower T* indicative for an onset of Se out-of-plane atomic displacements. T* coincides with a DC resistivity maximum and the onset of the proposed gyrotropic electronic structure. However, no indication for chirality is found. The relation between the atomic displacements and the transport properties is discussed in terms of Ti 3d and Se 4p states that only weakly couple to the CDW order.

Isolation, characterization and semi-synthesis of natural products dimeric amide alkaloids

Isolation, characterization and semi-synthesis of natural products dimeric amide alkaloids

Synchronized "One-Step" Resection and Cranio-Orbital Reconstruction for Spheno-Orbital Lesions With Custom Made Implant.

In the last few years, skull base tumors involving the fronto-orbital region have been approached with complex, invasive, and time-consuming cranial reconstruction techniques. On the other hand, recent custom-made implants allow easier and faster procedures, with excellent aesthetic results. The authors propose an easy surgical-planned protocol with a synchronized "one-step" resection and reconstruction of these complex lesions, with a preformed poly-methyilmethacrylate (PMMA) cranioplasty. Our technique consists of a 2-phases procedure. In the first one, the so-called "virtual" phase, the authors get a tailored 3D-PMMA model based on high-resolution (HR) CT-scans of the patient's skull. Afterward, the authors perform the planned craniotomy on the 3D-PMMA model with the assistance of intraoperative navigation system. Therefore, a further CT-scan of the resected model is performed to develop the final implant. In the second phase, the "surgical phase," a single procedure consisting in a cranial resection and custom reconstruction is performed with the assistance of stealth-navigation. The authors describe 6 cases of complex fronto-orbital-sphenoidal benign tumors that required skull reconstruction. All patients were examined 3 months after surgery through cosmetic (facial and eyes symmetry and globe position) and ophthalmology tests (visual field, visual impairment, and diplopia). Postsurgical HR CT-scans of the head and MRI-scans of the brain documented a total resection of the tumor and an optimal accuracy of skull reconstruction. In all cases, the authors obtained a highly accurate skull reconstruction following cranio-orbital tumor resection, with a less aggressive and faster procedure compared to autologous bone graft. Final cosmetic and functional results were excellent, with good results in cases of presurgical exophthalmos and orbital asymmetry. None of the patients developed implant-related complications. The "one-step" resection and reconstruction of benign tumors involving the spheno-orbital region with neuronavigation assistance is a technique that allows an accurate tumor removal and a cranial-bone reconstruction within a single surgical procedure, with fewer complications and excellent cosmetic and functional results.

Comparison of orbital asymmetries among some raptor species: “when size does not matter”

Abstract A sample of 73 dry, well-preserved skulls was studied, representing various species of raptors with different foraging strategies. The sample included Accipiter nisus (n = 15), Buteo buteo (n = 13), Gyps fulvus (n = 24) and Neophron percnopterus (n = 5), Bubo bubo (n = 16) and Tyto alba (n = 2). Geometric morphometric methods were used to detect orbital asymmetries. On digital pictures of each skull side, a set of 16 semi-landmarks and two landmarks were located in order to describe the orbital ring. The variables were analysed based on Generalized Procrustes analysis. The morphometric data showed that the orbital asymmetry of raptors differed significatively between species, although directional asymmetry (e.g. left orbita systematically more developed than the right) appeared not to be correlated with orbital size. This indicates that larger orbitas do not lead to greater asymmetry. Differences between species should rather be explained by their foraging strategies and degree of visual obstruction in their natural environment.

Combined unilateral coronal-lambdoid suture synostosis: surgical outcome of suturectomy and postoperative helmet therapy.

Nonsyndromic, multi-suture craniosynostosis is not common, especially those involving unilateral coronal and lambdoid sutures. Based on the experience on 6 cases, we analyzed the skull morphology of combined unilateral coronal-lambdoid suture synostosis and evaluated the surgical outcome of suturectomy. Patients who underwent an operation for craniosynostosis in Seoul National University Children's Hospital from 2010 to 2018 were reviewed. For qualitative analysis of the surgical outcome, five typical morphologic characteristics (ipsilateral superior orbital rim deviation, deviation of the nasal ridge, ipsilateral frontal flattening, contralateral parietal bulging, ipsilateral occipitomastoid bulging) in unilateral coronal-lambdoid suture synostosis were evaluated based on medical photos, plain skull radiographs, and CT scans. For quantitative analysis, three parameters (nasal root deviation, orbital asymmetry, posterior skull base deviation) were measured. Among 316 patients with craniosynostosis, 41 patients had nonsyndromic, multi-suture synostosis. There were 6 unilateral coronal-lambdoid suture synostosis patients who were all treated with suturectomy. Qualitative evaluation of the postoperative outcome revealed that the nasal root and orbital rim deviations and the contralateral occipitomastoid bulging showed satisfactory improvements. However, ipsilateral frontal flattening and contralateral parietal bulging were improved but still present in most cases. Quantitative, craniometric analysis supported the qualitative outcomes. The nasal ridge deviation angle was corrected from 7.04 to 1.79 degrees. The posterior skull base deviation angle improved from 6.29 to 3.55 degrees. Unilateral coronal-lambdoid suture synostosis suturectomy followed by helmet therapy resulted in favorable outcomes, although the correction of frontal flattening was less satisfactory than the other measures. Considering the minimal invasiveness of the treatment, suturectomy may be a viable option for these patients.

Anatomic Variability of the Human Orbit

Knowledge of the bony orbit and how its volume changes are clinically important in addressing traumatic injuries. Restoration of orbital volume in some patients is critical to achieving successful outcomes after such injuries. In this large cadaveric study, we aimed to assess the average volume, range of bony orbit volumes, degree of volume discrepancy between the right and left orbits, and percentage of skulls with 1- and 1.5-mL orbital volume differences via alginate impressions and volume displacement. This study used 121 skulls (242 orbits) from the University of Texas Southwestern Department of Cell Biology/Anatomy.Seal-press wrap was first adapted to each bony orbit to ensure no damage to the internal orbits, foramina, or fissures. Alginate impressions were then taken and trimmed to encompass the bony orbit. The volume of each impression was calculated via the volume-displacement method. The average orbital volume was 26.75mL for the right side and 26.65mL for the left. The average right-to-left difference between orbits was 0.8mL, with a range from 0.02 to 3.64mL. The calculated methodologic error was 0.91% for the right orbit and 1.05% for the left.Approximately 14% and 21% of skulls showed normal left-to-right orbital volume differences of 1.5mL or greater and 1.0mL or greater, respectively. Our data suggest that the average normal asymmetry between the right and left orbital volumes is 0.8mL, which is 50 to 80% of the orbital volume increase implicated in traumatic enophthalmos. Of the skulls, 17 (14%) showed a right-to-left orbital volume asymmetry of 1.5mL or greater and 25 (21%) showed an asymmetry of 1.0mL or greater. The skull-to-skull orbital volume range approached 200%. Thus, this study provides surgeons with important information to consider when reconstructing a traumatized orbit using a computed tomography scan of the unaffected, contralateral orbit.

Dose-Effect Analysis of Early Changes in Orbital Bone Morphology After Radiation Therapy for Rhabdomyosarcoma

PurposeIn survivors of orbital embryonal rhabdomyosarcoma (ERMS), late effects include facial deformation and asymmetry. We sought to quantify orbital asymmetry in ERMS survivors and characterize the dose effect of radiation to the orbital bones. Methods and MaterialsWe evaluated the most recent follow-up magnetic resonance imaging (MRI) in 17 children (≤21 years old) with stage 1 group III orbital ERMS treated with proton therapy between 2007 and 2018. For all patients, the orbital socket volumes were calculated and compared with the contralateral, unirradiated orbital socket. Patient age, orbital tumor quadrant, and the radiation dose delivered to the major orbital bones (maxillary, frontal, and zygomatic bones) were recorded and correlated with the orbital socket volume difference. ResultsThe mean age at diagnosis was 5.4 years old (range, 1.1-9.7 years). All patients received a prescription dose of 45 GyRBE. The mean time interval between radiation and MRI was 2.9 years (range, 0.8-3.2 years). The mean age at most recent MRI was 8.4 years (range, 2.3-12.9 years). In 16 of 17 patients, the volume of the ipsilateral orbit was significantly smaller than the contralateral orbit on follow-up MRI (P ≤ .0001). In one patient with nonviable tumor in situ, the irradiated orbit was larger. The volume difference increased with follow-up time and did not correlate with age at treatment or age at MRI. A dose >40 GyRBE to all bones of the orbital rim was associated with a significant decrease in orbital volume (P < .05), but an isolated dose of >40 GyRBE to either the frontal, maxillary, or zygomatic bone was not. ConclusionsDespite the dosimetric precision of proton therapy, orbital asymmetry will develop after >40 GyRBE to multiple bones of the orbital rim. These data may be used to guide treatment planning and counsel patients on expected cosmesis.

S6A-08 SESSION 6A: CORONAL SYNOSTOSIS NASAL MONOBLOC FOR CORRECTION OF LATE NASAL AND ORBITAL ASYMMETRY OF UNICORONAL SYNOSTOSIS (UCS): A MORPHOMETRIC AND OUTCOMES ANALYSIS.

Introduction: Despite best efforts, surgical correction of UCS in infancy often results in residual naso-orbital asymmetry that persists into adulthood. The aim of this study is to describe the results of a nasal monobloc procedure for secondary correction of the late nasal and orbital asymmetry of unicoronal synostosis by mobilizing a united nasal and medial orbital segment of bone to perform corrective translational and rotational movement. Methods: A retrospective review of all UCS patients treated with nasal monobloc at our institution was performed. Demographic information was recorded, and relevant imaging (3D and 2D photographs) was utilized for morphometric outcome analysis. Outcomes and complications were tabulated. Results: 14 patients with a mean age of 14.5 years (10.4 to 20.2 years) underwent the nasal monobloc procedure. Follow up was 13.5 to 68.1 months (mean = 22.6 months). There were no complications in our series. One patient had a repeat procedure following technique modification. All patients were satisfied with their outcome, and no subsequent revisions were performed. 3D morphometric analysis demonstrated correction of frontal nasal deviation by 67.24% (5.35 degrees), basal nasal deviation by 62.47% (4.52 degrees), and aperture index asymmetry by 79.95%. Frontal nasal deviation decreased from a mean of 7.58 degrees (SD = 1.58) to 3.44 degrees (SD = 3.81), p = 0.006. Axial deviation also was corrected from 5.93 degrees (SD = 2.75) to 2.47 degrees (SD = 1.71), p = 0.004. Aperture symmetry was improved from an index of 1.06 (SD = 0.11) to 0.99 (SD = 0.03), p = 0.002. Conclusion: Late naso-orbital asymmetry is a consistent sequela following the surgical correction of unicoronal synostosis in infancy. Nasal monobloc now provides a reasonable surgical treatment to improve both the nasal and orbital asymmetries associated with unicoronal synostosis, including frontal nasal deviation, basal nasal deviation, and orbital aperture asymmetry.

Facial Paralysis in Patients With Hemifacial Microsomia: Frequency, Distribution, and Association With Other OMENS Abnormalities.

Although facial paralysis is a fundamental feature of hemifacial microsomia, the frequency and distribution of nerve abnormalities in patients with hemifacial microsomia remain unclear. In this study, the authors classified 1125 cases with microtia (including 339 patients with hemifacial microsomia and 786 with isolated microtia) according to Orbital Distortion Mandibular Hypoplasia Ear Anomaly Nerve Involvement Soft Tissue Dependency (OMENS) scheme. Then, the authors performed an independent analysis to describe the distribution feature of nerve abnormalities and reveal the possible relationships between facial paralysis and the other 4 fundamental features in the OMENS system. Results revealed that facial paralysis is present 23.9% of patients with hemifacial microsomia. The frontal-temporal branch is the most vulnerable branch in the total 1125 cases with microtia. The occurrence of facial paralysis is positively correlated with mandibular hypoplasia and soft tissue deficiency both in the total 1125 cases and the hemifacial microsomia patients. Orbital asymmetry is related to facial paralysis only in the total microtia cases, and ear deformity is related to facial paralysis only in hemifacial microsomia patients. No significant association was found between the severity of facial paralysis and any of the other 4 OMENS anomalies. These data suggest that the occurrence of facial paralysis may be associated with other OMENS abnormalities. The presence of serious mandibular hypoplasia or soft tissue deficiency should alert the clinician to a high possibility but not a high severity of facial paralysis.