Assessment and Comparison of Cervical Column Morphology and Cranial Base Angle in Three Different Facial Types - A Cephalometric Study

We wanted to assess and compare the morphological deviations of the cervical vertebral column and cranial base angle in three different facial types that is hypodivergent, normodivergent and hyperdivergent groups and elucidate the aetiology behind the associations as well as clinical implications of the results. MethodsThe study was conducted in the department of orthodontics wherein lateral cephalograms of 150 subjects in the age group of 18 - 25 years were taken and divided into three groups. The division of groups was made as per Steiner’s mandibular plane angle i.e. Hyperdivergent group (SN–MP angle >34 degrees) Normodivergent group (SN–MP angle 26- 34 degrees) Hypodivergent group (SN–MP angle < 26 degrees). Lateral cephalograms were traced and analysed to compare the variables by statistical analysis. Morphology of the cervical column was evaluated by visual inspection of the first 5 cervical vertebrae as they are normally seen on a standardized lateral skull radiograph. Characteristics of the cervical column were classified according to the method of Sandham. The cranial base angle was measured by the angle between nasion sella and sella basion (N-S-Ba) and then compared in the three groups. ResultsThe cranial base angle was increased significantly in the hyperdivergent group and decreased in the hypodivergent group when compared to the normodivergent group patients. However, no significant results were associated regarding the morphology of the cervical column in the three groups. ConclusionsAssociations between the cranial base angle and cervical column morphology plays a pivotal role in orthodontics in making the diagnosis of malocclusion and finding out the pattern of growth in vertical direction. A routine examination of the cervical vertebral column area for any deviation in the morphology should be done and checked. These registrations may prove useful in making the diagnosis and finding aetiology especially in the cases of severe skeletal malocclusions like severe open bite and deep bite and those with obstructive disorders like obstructive sleep apnoea or enlarged adenoids.

Anatomical Variant of Atlas : Arcuate Foramen, Occpitalization of Atlas, and Defect of Posterior Arch of Atlas

OBJECTIVE: We sought to examine anatomic variations of the atlas and the clinical significance of these variations. METHODS: We retrospectively reviewed 1029 cervical 3-dimensional (3D) CT images. Cervical 3D CT was performed between November 2011 and August 2014. Arcuate foramina were classified as partial or complete and left and/or right. Occipitalization of the atlas was classified in accordance with criteria specified by Mudaliar et al. Posterior arch defects of the atlas were classified in accordance with criteria specified by Currarino et al. RESULTS: One hundred and eight vertebrae (108/1029, 10.5%) showed an arcuate foramen. Bilateral arcuate foramina were present in 41 of these vertebrae and the remaining 67 arcuate foramina were unilateral (right 31, left 36). Right-side arcuate foramina were partial on 18 sides and complete on 54 sides. Left-side arcuate foramina were partial on 24 sides and complete on 53 sides. One case of atlas assimilation was found. Twelve patients (12/1029, 1.17%) had a defect of the atlantal posterior arch. Nine of these patients (9/1029, 0.87%) had a type A posterior arch defect. We also identified one type B, one type D, and one type E defect. CONCLUSION: Preoperative diagnosis of occipitalization of the atlas and arcuate foramina using 3D CT is of paramount importance in avoiding neurovascular injury during surgery. It is important to be aware of posterior arch defects of the atlas because they may be misdiagnosed as a fracture.

Occipitalization of Atlas.

Occipitalization of atlas is an osseous anomaly of the craniovertebral junction which occurs at the base of the skull in the region of the foramen magnum. The knowledge of such a fusion is important because skeletal abnormalities at the craniocervical junction may result in sudden death. During bone cleaning procedure and routine undergraduate osteology teaching, three skulls with Occipitalization of atlas were encountered in the department of Anatomy atMMIMSR,Mullana, India. In one skull, both anterior and posterior archwere completely fused with occipital bone while the transverse process on the right side was not fused whereas left transverse process was fused with occipital bone. Both anterior and posterior arch were completely fused whereas transverse process on both sides were not fused in other skull. In another skull, partial and asymmetrical Occipitalization of atlas vertebra with occipital bone was found with bifid posterior arch of atlas at the level of posterior tubercle. Anterior arch was completely fused with basilar part of occipital bone but both the transverse processes were not fused. Reduced diameter of foramenmagnum due to the atlanto-occipital fusion might cause neurological complications due to compression of spinal cord or medulla oblongata, vertebral vessels, 1st cervical nerve, thus, knowledge of occipitalization of the atlas may be of substantial importance to orthopaedicians, neurosurgeons, physicians and radiologists dealing with abnormalities of the cervical spine.

Cervical vertebral anomalies in skeletal malocclusions: A cross-sectional study on orthodontic patients at the Aga Khan University Hospital, Pakistan.

Introduction: Morphological deviations of the cervical vertebral column have been described in relation to craniofacial aberrations and syndromes. Furthermore, it has recently been shown that abnormal morphology of upper cervical vertebrae is associated with malformation of the jaws and occlusion. Accordingly, it is relevant to focus on similar associations in patients with skeletal malocclusions. Therefore, the objectives of this study are to: • Identify the anomalies of the cervical column in patients with skeletal malocclusions • Determine the association between cervical vertebral anomalies and skeletal malocclusions. Materials and Methods: This cross‑sectional study was conducted on a total of 90 subjects at the Aga Khan University Hospital, Pakistan. The inclusion criteria were: (1) Pakistani origin; (2) standardized pretreatment profile radiograph with first six cervical vertebrae visible; and (3) accessibility of the second‑profile radiograph (mid‑ or posttreatment). The exclusion criteria were: (1) A prior history of orthodontic treatment; (2) any craniofacial anomaly; and (3) systemic muscle or joint disorder. Lateral cephalograms of all subjects (n = 90) were traced by the principal investigator and sagittal jaw relationship was assessed. A total of 30 subjects each with skeletal Class I, Class II, and Class III malocclusions were selected and the cervical vertebral anomalies were observed on their cephalometric radiographs. The frequencies of cervical vertebral anomalies according to skeletal malocclusion categories and gender were analyzed with the Chi‑square test, whereas association of cervical vertebral anomalies with skeletal malocclusions was assessed with logistic regression analysis. The level of significance (P ≤ 0.05) was used for the statistical tests. Results: Most common anomaly observed in the three groups was fusion between C2 and C3 (P = 0.006). This anomaly was found in 20% of subjects with skeletal Class I, 50% of subjects with skeletal Class II and 53.3% with skeletal Class III malocclusions. The highest frequencies of partial cleft at the level of C1 and occipitalization were observed in subjects with skeletal Class II and III malocclusions, respectively. However, none of the subjects showed fusion between C1 and C2 or dehiscence. No statistically significant gender difference was found in the occurrence of morphological deviations of the cervical column. The association of cervical vertebral anomaly was found to be the highest with skeletal Class III and lowest with skeletal Class I malocclusions. Conclusion: Fusion between C2 and C3 seems to be the most commonly occurring anomaly. This anomaly seems to be more often associated with skeletal Class III than skeletal Class I or Class II malocclusions.

Synostosis of atlas with occipital bone-occurrence and clinical application.

Synostosis also known as occipitalization of the atlas is a rare congenital malformation at craniovertebral junction. Atlas, the first cervical vertebra forms the ellipsoidal synovial joints with the condyles of the occipital bone. Rarely it gets occipitalized where the condyles fuse with the lateral masses of the atlas. During the morphometric study of hundred skulls in Department of Anatomy, Sri Guru Ram Das Institute of Medical Sciences and Research, Vallah, two skulls showed the incomplete occipitalization of the atlas vertebrae. The partial or complete assimilation of atlas may have resulted due to the disruption in the separation of caudal part of the first sclerotome from the cranial part of the first sclerotome.