Vestibular orientation for craniofacial surgery: application to the management of unicoronal synostosis

Management of hypertelorism

Aim:

To summarize the experience of the author with the treatment of hypertelorism.

Settings and Design:

The author has been heading a high-caseload department of craniofacial surgery for 38 years; the research is based on his experience with this pathology by this time.

Materials and Methods:

The charts of 38 patients were used for this research.

Statistical Analysis Used:

No statistic was used; the author has just given his personal insights as the result of a professional life devoted to the problem.

Results:

Most of the hypertelorism cases requiring surgical correction are rare interorbital clefts (Tessier’s 14–12). Among the syndromic ones, cranio-fronto orbital dysplasia is the most demanding for surgery because it is associated with craniosynostosis, which has to be addressed at the same time. Among the technics published for hypertelorism correction, craniofacial bipartition has our preference for several reasons: easily done and redone when necessary, safer to the vascularization, and trophicity of displaced parts of the skeleton.

Conclusions:

Complex craniofacial conditions such as hypertelorism have to be treated only in specialized craniofacial centers by a multidisciplinary team. The caseload has to be high, and the follow-up is very strict to get the benefits of experience to improve the results.

Three-dimensional study of 31 cases of synostotic anterior plagiocephaly before and after surgical management the Lille protocol

Synostotic anterior plagiocephaly is a rare pathological cranial malformation. Therapeutic options are rarely studied due to the rarity of the malformation and difficulties in diagnosis and care management. The objective of this study was to analyze the results obtained with the Lille protocol based on 62 CT-scans done before and after surgery in 31 patients. A specific analysis was designed for this work. Nine cephalometric measures enabled to evidence on each CT-Scan the corrections made on the fronto-orbital bandeau and the potential impact of surgery on the craniofacial structures. Results show that surgical symmetry of the fronto-orbital bandeau in the transversal plane, according to the symmetrical axis of the semicircular canals, allows a normalization of the skull's growth and morphogenesis for the surgically affected structures but also adjacent ones.

Comparative validity and reproducibility study of various landmark-oriented reference planes in 3-dimensional computed tomographic analysis for patients receiving orthognathic surgery

Background

Three-dimensional computed tomographic imaging has become popular in clinical evaluation, treatment planning, surgical simulation, and outcome assessment for maxillofacial intervention. The purposes of this study were to investigate whether there is any correlation among landmark-based horizontal reference planes and to validate the reproducibility and reliability of landmark identification.

Materials and Methods

Preoperative and postoperative cone-beam computed tomographic images of patients who had undergone orthognathic surgery were collected. Landmark-oriented reference planes including the Frankfort horizontal plane (FHP) and the lateral semicircular canal plane (LSP) were established. Four FHPs were defined by selecting 3 points from the orbitale, porion, or midpoint of paired points. The LSP passed through both the lateral semicircular canal points and nasion. The distances between the maxillary or mandibular teeth and the reference planes were measured, and the differences between the 2 sides were calculated and compared. The precision in locating the landmarks was evaluated by performing repeated tests, and the intraobserver reproducibility and interobserver reliability were assessed.

Results

A total of 30 patients with facial deformity and malocclusion—10 patients with facial symmetry, 10 patients with facial asymmetry, and 10 patients with cleft lip and palate—were recruited. Comparing the differences among the 5 reference planes showed no statistically significant difference among all patient groups. Regarding intraobserver reproducibility, the mean differences in the 3 coordinates varied from 0 to 0.35 mm, with correlation coefficients between 0.96 and 1.0, showing high correlation between repeated tests. Regarding interobserver reliability, the mean differences among the 3 coordinates varied from 0 to 0.47 mm, with correlation coefficients between 0.88 and 1.0, exhibiting high correlation between the different examiners.

Conclusions

The 5 horizontal reference planes were reliable and comparable for 3D craniomaxillofacial analysis. These reference planes were useful in standardizing the orientation of 3D skull models.

The variability of inner ear orientation in saurischian dinosaurs: testing the use of semicircular canals as a reference system for comparative anatomy

The vestibular system of the inner ear houses three semicircular canals—oriented on three nearly-orthogonal planes—that respond to angular acceleration stimuli. In recent years, the orientation of the lateral semicircular canal (LSC) has been regularly used to determine skull orientations for comparative purposes in studies of non-avian dinosaurs. Such orientations have been inferred based on fixing the LSC to a common set of coordinates (parallel to the Earth’s horizon), given that the orientation to gravity of this sensory system is assumed constant among taxa. Under this assumption, the LSC is used as a baseline (a reference system) both to estimate how the animals held their heads and to describe craniofacial variation among dinosaurs. However, the available data in living birds (extant saurischian dinosaurs) suggests that the orientation of the LSC in non-avian saurischian dinosaurs could have been very variable and taxon-specific. If such were the case, using the LSC as a comparative reference system would cause inappropriate visual perceptions of craniofacial organization, leading to significant descriptive inconsistencies among taxa. Here, we used Procrustes methods (Geometric Morphometrics), a suite of analytical tools that compares morphology on the basis of shared landmark homology, to show that the variability of LSC relative to skull landmarks is large (ca. 50°) and likely unpredictable, thus making it an inconsistent reference system for comparing and describing the skulls of saurischian (sauropodomorph and theropod) dinosaurs. In light of our results, the lateral semicircular canal is an inconsistent baseline for comparative studies of craniofacial morphology in dinosaurs.

Unicoronal synostotic plagiocephaly: surgical correction: Lille's technique

INTRODUCTION

For 35 years, we have a tight neuro-plastic surgical cooperation for the surgical correction and long-term systematic follow-up of 125 cases of unicoronal synostotic plagiocephaly.

METHODS

We have tried to understand why some patients had kept an asymmetrical facial growth pattern in spite of a good fronto orbital correction. Analysis in vestibular orientation which was available from 1993 has demonstrated a discrepancy between the ocular and the vestibular verticality referential system. So we have designed a surgical procedure to try to fix that problem.

RESULTS AND CONCLUSION

Preliminary results in 27 cases operated according to this procedure, for which we have pre- and post-CT scan demonstrate significative improvements of our results.

Non-syndromic oxycephaly and brachycephaly: a review

BACKGROUND

Non-syndromic coronal synostoses oxycephaly and brachycephaly (NSCSOB) are rare. Their natural history, surgical management, and outcome are debated.

MATERIAL AND METHODS

We reviewed the available literature on NSCSOB. In addition, we reviewed retrospectively our experience with cases of NSCSOB, managed and operated by our joint craniofacial team since 1984. Newborns underwent perifrontal craniectomy, while infants and older children underwent fronto-orbital advancement with frontoparietal remodeling. Cases with delayed onset of faciosynostosis were excluded.

RESULTS

Some cases of NSCSOB present at birth or even prenatally with gross dysmorphism and severe brachycephaly; others present later in life with harmonious restriction of intracranial volume and are at risk for development and vision. Some NSCSOB evolve from initially unisutural synostoses. We treated 61 cases, operated aged 1.4 to 106.7 months, 30 with brachycephaly and 31 with oxycephaly. Twelve of these (19.7 %), had been treated initially for sagittal or unicoronal synostosis, and evolved into NSCSOB. Intracranial hypertension was present initially in 28 (45.9 %), with ophthalmological consequences in 13 (21.3 %) and mental retardation in 6 (9.6 %). No patient had hydrocephalus; only two had asymptomatic Chiari malformation. The mean postoperative follow-up was 113.6 months. At last control, 21 patients had developmental delay and 5 had visual impairment.

CONCLUSIONS

NSCSOB are a complex entity. They have in common a high risk of severe intracranial hypertension and rare hydrodynamic complications. Genetic screening is necessary to assert their non-syndromic nature. Prolonged follow-up of all craniosynostoses is necessary because unisutural synostoses can evolve into NSCSOB, and NSCSOB can evolve into craniofaciosynostosis.

Orbital change following Le Fort III advancement in syndromic craniosynostosis: quantitative evaluation of orbital volume, infra-orbital rim and globe position

Patients with syndromic craniosynostosis suffering from shallow orbits due to midface hypoplasia can be treated with a Le Fort III advancement osteotomy. This study evaluates the influence of Le Fort III advancement on orbital volume, position of the infra-orbital rim and globe. In pre- and post-operative CT-scans of 18 syndromic craniosynostosis patients, segmentation of the left and right orbit was performed and the infra-orbital rim and globe were marked. By superimposing the pre- and post-operative scans and by creating a reference coordinate system, movements of the infra-orbital rim and globe were assessed. Orbital volume increased significantly, by 27.2% for the left and 28.4% for the right orbit. Significant anterior movements of the left infra-orbital rim of 12.0mm (SD 4.2) and right infra-orbital rim of 12.8mm (SD 4.9) were demonstrated. Significant medial movements of 1.7mm (SD 2.2) of the left globe and 1.5mm (SD 1.9) of the right globe were demonstrated. There was a significant correlation between anterior infra-orbital rim movement and the increase in orbital volume. Significant orbital volume increase has been demonstrated following Le Fort III advancement. The position of the infra-orbital rim was moved forward significantly, whereas the globe position remained relatively unaffected.

Evaluation of 2 different reference planes used for the study of asymmetric facial malformations

The purpose of this study was to evaluate if Frankfort plane (FH) and plane passing through the lateral semicircular canals (LS) can be used as reference planes in three-dimensional analysis.Ten patients with facial asymmetry underwent a three-dimensional computed tomography. Computed tomographic images were processed by means of a commercial software and a personal computer to obtain a three-dimensional virtual craniofacial model. The average Frankfort plane and the plane passing through the LS were identified. The distance from the above-mentioned planes to the first upper molar and upper canine cusp was measured.It was not possible to detect an FH plane in any of the patients. Right FH, left FH, average FH, and LS plane were traced. The discrepancies among reference planes were significant in cases with severe asymmetry. A minimal discrepancy was noticed in patients with light asymmetry.In patients with severe asymmetry, the LS plane results in steady, reproducible, detectable, and closer to the patient's anatomy, representing a valid reference plane for three-dimensional computed tomography analysis.