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Purpose: The topic of osseous variations of the craniocervical junction is a complex morphological and embryological chapter of human anatomy, with a possible impact on neurogical and vascular functionality in this morphological variable region., Material & Methods: An until now undescribed anatomical variation of the exoccipital part of the occipital bone has been observed after maceration at the outer skull base of a West-European 68-year-old male body donor., Results: On both sites of the foramen magnum accessory osseous processes were observed that arise from the jugular process and point towards the lateral margin of the foramen magnum. On the left site this process forms a full arc that bridges the condylar fossa completely., Conclusion: The observed osseous bridge over the condylar fossa has not been reported on before and can be explained by the partial persistence of a primordial vertebra between atlas and occipital bone: the Proatlas. The resulting accessory structure may affect due to its topographic conditions the V3-Segment of the vertebral artery and its accompanying nerves, and thus, play a role in diagnosis and therapy of vascular and/or neurological symptoms of head and neck., (© 2024. The Author(s).)

The objective of this study is to present the two cases of cervical hemivertebra and torticollis, and To describe technique and result of cervical hemivertebra resection and torticollis correction via a anterior-posterior surgical approach and occipitocervical fusion. Cervical hemivertebra, accompanied by abipartite atlas, agenesis of odontoid and C2 segmental type of vertebral artery (VA), is a rare, but complex congenital anomalies, associated with cervical scoliosis and occipitocervical instability. To the best of our knowledge, this is the first report on such congenital anomaly and deformity correction via anterior-posterior hemivertebra resection with occipitocervical fusion. Two patients were presented with torticollis due to congenital cervical hemivertebra accompanied by abipartite atlas, agenesis of odontoid and C2 segmental type of VA. Deformity correction was executed by an anterior-posterior hemivertebra resection and occipitocervical fusion with segment instrumentation. The treatment course was uneventful and clinical outcomes was favorable. The radiographs showed a satisfactory deformity correction with a well-balanced coronal and sagittal alignment. Hemivertebra resection with occipitocervical fusion could correct torticollis with satisfactory clinical and radiographical outcome.

Purpose: To describe a case of an anomalous posterosuperior course of the V3 segment of the right vertebral artery (VA) that penetrated the occipital bone (wall of the jugular foramen)., Methods: A 33-year-old healthy woman underwent cranial magnetic resonance (MR) imaging and MR angiography from the upper cervical to the intracranial region using a 3-Tesla scanner to screen for asymptomatic brain lesions, including cerebrovascular diseases., Results: MR angiography showed no pathological arterial lesions such as aneurysms; however, there was an anomalous posterosuperior course of the V3 segment of the right VA. On MR angiographic source images and coronal reformatted images, the right VA was observed to penetrate the occipital bone lateral to the right hypoglossal canal and is located on the inferoposteromedial wall of the right jugular foramen and enter the posterior fossa at a higher level than the foramen magnum., Conclusion: We present a case in which the right VA showed an anomalous posterosuperior course at the craniovertebral junction. It is extremely rare for a VA to take a higher course. To our knowledge, this is the first report of such a VA variation in the relevant English-language literature. We speculated that the right VA of our patient was formed by the persistence of one more cephalad primitive artery than the first intersegmental artery, not by the persistence of the primitive hypoglossal artery. Careful observation of MR angiographic source is useful and important for identifying the VA penetrating the occipital bone., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Objective: Congenital anomalies of the atlanto-occipital articulation may be present in patients with Chiari malformation type I (CM-I). However, it is unclear how these anomalies affect the biomechanical stability of the craniovertebral junction (CVJ) and whether they are associated with an increased incidence of occipitocervical fusion (OCF) following posterior fossa decompression (PFD). The objective of this study was to determine the prevalence of condylar hypoplasia and atlas anomalies in children with CM-I and syringomyelia. The authors also investigated the predictive contribution of these anomalies to the occurrence of OCF following PFD (PFD+OCF)., Methods: The authors analyzed the prevalence of condylar hypoplasia and atlas arch anomalies for patients in the Park-Reeves Syringomyelia Research Consortium database who underwent PFD+OCF. Condylar hypoplasia was defined by an atlanto-occipital joint axis angle (AOJAA) ≥ 130°. Atlas assimilation and arch anomalies were identified on presurgical radiographic imaging. This PFD+OCF cohort was compared with a control cohort of patients who underwent PFD alone. The control group was matched to the PFD+OCF cohort according to age, sex, and duration of symptoms at a 2:1 ratio., Results: Clinical features and radiographic atlanto-occipital joint parameters were compared between 19 patients in the PFD+OCF cohort and 38 patients in the PFD-only cohort. Demographic data were not significantly different between cohorts (p > 0.05). The mean AOJAA was significantly higher in the PFD+OCF group than in the PFD group (144° ± 12° vs 127° ± 6°, p < 0.0001). In the PFD+OCF group, atlas assimilation and atlas arch anomalies were identified in 10 (53%) and 5 (26%) patients, respectively. These anomalies were absent (n = 0) in the PFD group (p < 0.001). Multivariate regression analysis identified the following 3 CVJ radiographic variables that were predictive of OCF occurrence after PFD: AOJAA ≥ 130° (p = 0.01), clivoaxial angle < 125° (p = 0.02), and occipital condyle-C2 sagittal vertical alignment (C-C2SVA) ≥ 5 mm (p = 0.01). A predictive model based on these 3 factors accurately predicted OCF following PFD (C-statistic 0.95)., Conclusions: The authors' results indicate that the occipital condyle-atlas joint complex might affect the biomechanical integrity of the CVJ in children with CM-I and syringomyelia. They describe the role of the AOJAA metric as an independent predictive factor for occurrence of OCF following PFD. Preoperative identification of these skeletal abnormalities may be used to guide surgical planning and treatment of patients with complex CM-I and coexistent osseous pathology.

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion., Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis., Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest's Craniofacial Imaging Database (WFCID)., Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery., None., 2D and 3D cephalometric measurements., 3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = -398.75; P  < .05) and petrous-occipital (β = -727.5; P  < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = -14 723.1; P  < .001) and occipitomastoid synchondrosis (β = -16 419.3; P  < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = -673.3; P  < .001), anterior intraoccipital synchondrosis (β = -368.47; P  < .05), and posterior intraoccipital synchondrosis (β = -6261.42; P  < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion., Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

Aim: To determine a quantitative relationship between the postoperative clivus slope (CS) and the change in the Patient-Reported Japanese Orthopaedic Association (PRO-JOA) scores following reduction surgery of the basilar invagination (BI)., Material and Methods: A single center retrospective study was conducted. Patients who met the inclusion and exclusion criteria at our hospital during the period from August 2015 to August 2020 were identified. The CS was introduced. Radiographic parameters including the CS were measured to assess realignment preoperatively and postoperatively. The PRO-JOA score was recorded to reveal the clinical outcome. The PRO-JOA score and the radiographic parameters that included the CS were compared between postoperative BI patients., Results: Ninety-four patients with BI were included in the study. The CS (0.96, 0.93-1.00) was inversely correlated with the PROJOA score. The CS was negatively associated with the ΔPRO-JOA score in the crude model, while no significant associations in the fully adjusted model, although in the case of the latter, a slight trend was found (p for trend < < 0.05). In the non-linear model, the CS was negatively associated with the ΔPRO-JOA score in patients diagnosed with BI, unless the CS exceeded 63.4°., Conclusion: A reduction in the CS affects the postoperative PRO-JOA score of BI patients. This relationship can be employed as a quantitative reference in determining preoperative design with respect to the intraoperative correction needed to reduce craniovertebral junction deformity in BI.

Morphological changes in the child skull due to mechanical and metabolic stimulation and synostosis of the suture are well known. On the other hand, few studies have focused on clinical conditions relevant for adult skull deformity. We retrospectively reviewed computed tomography (CT) findings obtained from 365 cases that were treated for head injuries, moyamoya disease, cervical internal carotid artery stenosis, and mental diseases, and investigated the morphological changes in the skull associated with these diseases. The findings from head injuries were used not only for control subjects, but also for the analysis of generational changes in skull shape based on birth year. Head shape had a brachiocephalic tendency with occipital flattening in people born from the 1950s onwards. Cases of moyamoya disease, cervical internal carotid artery stenosis, and mental diseases showed significantly thicker frontal and occipital bone than those of control subjects. The skull thickening was especially noticeable in the frontal bone in moyamoya disease. Plagiocephaly was significantly frequent in moyamoya disease. These uncommon skull shapes are useful CT findings in screening subjects for early evidence of mental diseases and intracranial ischemic diseases with arterial stenosis., (© 2021. The Author(s).)

Atlas occipitalization (AO) is a spinal anomaly, characterized by the fusion of the first cervical vertebra and occipital bone, with a complex etiology that can arise from congenital and environmental causes. AO has been reported in three regions of pre-Hispanic Peru in skeletal remains with artificial cranial modification (ACM), which involves the use of compression devices to permanently alter cranial shape and may have affected the fusion of the atlas and occipital bone. The aims of this study were to gain insights into AO's etiology by testing correlations between AO and ACM presence/type and geographic region as well as to characterize morphological variation associated with AO. We investigated the geographic distribution of AO and its potential relationship to ACM in a large sample of human crania from eight coastal and highland regions of pre-Hispanic Peru, held at the Smithsonian's National Museum of Natural History (n = 608, 1300-1500 CE). Eleven cases of AO were observed in three coastal regions-including two previously unreported regions-at an overall frequency of 1.8%. The frequency of AO did not differ significantly between crania with and without ACM, in general or by type, suggesting that ACM is not an etiological factor that influences AO in this sample. AO was observed at a significantly higher rate in the southern coastal region of Arequipa than in any other region. Genetic, dietary, and epidemiological conditions are evaluated as factors possibly shaping the geographic distribution of AO along the central and southern coasts of Peru., Competing Interests: The authors have declared that no competing interests exist.

Aims: To review and present the current knowledge of incidence, signs and symptoms, diagnosis and treatment of the occipital encephalocele., Background: Encephalocele (E) is a defect of the neural tube that refers to congenital malformations featured by skull defect and dura with extracranial spread of intracranial structures. Occipital encephalocele (OE) are the most common form of this congenital disorder and are manifested as a swelling of different sizes over the occipital bone in the midline. Proper diagnosis and treatment is highly important in the management of this congenital malformation of brain., Objective: To review and present the current knowledge of incidence, signs and symptoms, diagnosis and treatment of the occipital encephalocele., Methods: We conducted a search of case reports or case-series of patients by the use of electronic databases: Pub Med, Medline, Index Medicus, Scorpus. The key words were: encephalocele, occipital encephalocele, neural tube defect, congenital malformation. The search was updated to December 31, 2018. Papers published in English were the only source of information., Results: Occipital encephalocelle are more frequent in females than in males. The incidence is between 1 in 3000 to 1 in 10,000 live births; approximately 90% of them involve the midline. Magnetic resonance imaging is the method of choice in diagnosis and surgery is the best option for the treatment of OE. Overall morbidity and mortality is still high in spite of advenced surgical management, but have been significantly improved in recent years thanks to sophisticated highresolution imaging, adequate and proper surgical treatment and decent post-operative care., Conclusion: Occipital encephalocele is the most common form of encephalocele. The diagnosis is mostly based by the use of neuroimaging techniques. Operation is the best option for treatment. Overall morbidity and mortality is still high, but have been significantly improved in recent years thanks to sophisticated high-resolution imaging, adequate and proper surgical treatment and decent post-operative care., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Patients with basilar invagination and atlas occipitalization usually present abnormal anatomy of the vertebral arteries (VAs) at the craniovertebral junction (CVJ)., Objective: To describe and further classify different types of VA variations at the CVJ with 3D visualization technology., Methods: One hundred twenty patients with basilar invagination and atlas occipitalization who had undergone 3-dimensional computed tomographic angiography (3D-CTA) were retrospectively studied. Imaging data were processed via the separating, fusing, opacifying, and false-coloring-volume rendering technique. Abnormal anatomy of the VA at the CVJ was categorized and related anatomic parameters were measured., Results: Seven different types were classified. Type I, VAs enter the cranium after leaving VA groove on the posterior arch of atlas (26.7% of 240 sides); Type II, VAs enter an extraosseous canal created in the assimilated atlas lateral mass-occipital condyle complex before reaching the cranium (53.3%); Type III, VA courses above the axis facet or curves below the atlas lateral mass then enter the cranium (11.7%); Type IV, VAs enter the spinal canal under the axis lamina (1.3%); Type V, high-riding VA (31.3%); Type VI, fenestrated VA (2.9%); Type VII, absent VA (4.2%). Distance from the canal of Type II VA to the posterior facet surface of atlas lateral mass (5.51 ± 2.17 mm) means a 3.5-mm screw can be safely inserted usually. Shorter distance from the midline (13.50 ± 4.35) illustrates potential Type III VA injury during exposure. Decreased height and width of axis isthmus in Type V indicate increased VA injury risks., Conclusion: Seven types of VA variations were described, together with valuable information helpful to minimize VA injury risk intraoperatively., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: Scaphocephaly is usually defined as the deformation of the skull resulting from the premature fusion of the sagittal suture. It is the most common type of craniosynostosis, and can be easily recognized on simple clinical examination. Its pathophysiology is easy to understand and to confirm on neuroradiological examination. In contrast, surgical indications are still somewhat controversial, the dispute mainly concerning therapeutic versus esthetic objectives. In recent years, however, several studies have challenged these basic and relatively simplistic interpretations of the pathophysiology of the condition., Materials and Methods: To assess the heterogeneity of scaphocephaly, we reviewed cases of scaphocephaly operated on at the Hôpital Femme-Mère-Enfant, Lyon University Hospital, France during a 10-year period (2008-2017) and performed a review of the literature on scaphocephaly and sagittal suture closure., Results: During the 10-year period, 401 children were operated on for a scaphocephaly at the Hôpital Femme Mère Enfant, Lyon University Hospital. Mean age at surgery was 1.14 years, for a median 0.7 years (range, 4 months to 8. 5 years). Several subtypes could be distinguished according to morphology, intracranial findings on imaging, patient age, and etiology associated to the sagittal synostosis. Two main surgical techniques were used to correct the malformation, depending on patient age, type of deformation and the surgeon's preference: cranial vault remodeling with occipital pole widening, with the patient in a prone position, and parietal enlargement with or without forehead remodeling, in dorsal decubitus., Conclusions: The complexity and heterogeneous nature of sagittal synostoses depend on different pathogenic mechanisms leading to and interfering with the skull abnormalities: abnormalities of CSF dynamics, possibly associated with systemic alterations, accounting for the varied postoperative morphological and functional course, in terms of cognitive impairment and late complications (notably intra-cranial pressure elevation). However, the real impact of such heterogeneous clinical presentations on surgical indications and surgical results remains to be elucidated., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Objective: To examine the effect of posterior reduction in atlantoaxial dislocation (AAD) associated with basilar invagination(BI) using Xuanwu occipital-cervical fusion system in single stage. Methods: Thirty-seven AAD accompanied with BI cases treated at Department of Neurosurgery, Xuanwu Hospital, Capital Medical Universiy and the Second Hospital of Hebei Medical University were retrospective analyzed. There were 15 males and 22 females with age of (42.3±12.3)years (range: 18-69 yars). All the cases had congenital osseous abnormalities, such as assimilation of atlas and abnormal cervical fusion. Anterior tissue was released through posterior route followed by cage implantation into facet joint and occipital-cervical fixation with cantilever technique. The clinical results were evaluated using Japanese Orthopedic Association scale(JOA) and the main radiological measurements including anterior atlantodental interval (ADI),the distance of odontoid tip above Chamberlain line,clivus-canal angle (CCA) and the length of syrinx were collected.The preoperative and postoperative JOA score and radiological measurements were compared by paired t -test. Results: The mean JOA score of the patients increased from 10.5 to 14.4 at the one-year follow-up( t= 14.3, P= 0.00).Complete reduction of AAD and BI was achieved in 34 patients.The mean clivus-canal angle improved from 118.0 degrees preoperative to 143.7 degrees postoperative( t= 6.2, P= 0.00). Shrinkage of the syrinx was observed 1 week after surgery in 24 patients, and 6 months in 31 patients. Twenty-eight patients achieved bone fusion 6 months after surgery. All the patients achieved bone fusion 12 months after surgery. One-side vertebral artery occlusion was diagnosed in 1 case postoperatively for transient dizziness, and relieved in 2 weeks. Two patients developed moderate neck pain after surgery, and relieved in 1 month. No implant failure, spacer subsidence or infection was observed. Conclusions: The treatment of AAD associated with BI using Xuanwu occipital-cervical fusion system from posterior approach in single stage is effective and safe. Cage implantation intraarticularly and fixation with cantilever technique achieve complete reduction in most cases.

An adult male skeleton was submitted to the Department of Anatomy at the University of Belgrade for evaluation. It was believed to represent the remains of a second to third century Christian saint from the Lesje Monastery in central Serbia. Examination of the remains revealed an old crush fracture of a thoracic vertebra and an unusual, probably congenital, malformation of the atlanto-occipital joint with deformation of the left occipital condyle and resultant narrowing of the foramen magnum. Although the occipital malformations were most likely congenital, they may still have caused, or contributed to, death by compression of the underlying upper cervical spinal cord.

Occipital spur is an abnormal bony outgrowth of the external occipital protuberance (EOP). We describe an interesting and previously unreported case of fracture of an occipital spur following trauma. Our 20-year-old male patient was treated in the emergency department (ED) and discharged home without complication. Neurosurgical consultation was obtained but is not requisite for these injuries. Greater awareness of this unique presentation may help to expedite future emergency department treatment., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The craniovertebral junction (CVJ) is the bony transition between the cranium and cervical spine. It is a biomechanically complex articulation comprising the occipital condyles (Oc) the atlas (C1) and axis (C2). Pathologies affecting the CVJ in children are myriad with clinical features resulting from biomechanical instability, deformity, or neuraxial compression. Establishing the natural history and clinical burden of a condition is challenging in infants and young children, often complicated by co-existing neuromuscular and cognitive impairment. This makes investigation and treatment planning difficult. Each disease entity has a predilection for a particular biomechanical abnormality. Investigation using dynamic imaging is most appropriate in instability, computed tomography examination in abnormalities of deformity and magnetic resonance imaging examination in neuraxial compression. Treatment comprises reduction and immobilisation of instability, re-alignment of deformity, or decompression of the neuraxis. We present a review of disease entities affecting the CVJ in children categorised according to a simple mechanistic approach to aid investigation and treatment planning., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)

Torticollis could be the only symptom and sign of craniovertebral junction (CVJ) abnormality. It could be difficult to identify CVJ abnormality as a cause of torticollis due to their rarity, especially for the subjects with torticollis caused by nontraumatic CVJ abnormalities. There has been no report to focus on nontraumatic CVJ abnormalities as a cause of torticollis. The objective of this study was to report 27 patients of torticollis caused by nontraumatic CVJ abnormalities, with the aim of helping clinicians to identify nontraumatic CVJ abnormalities as a cause of torticollis. This is a retrospective cohort study including 27 subjects who had torticollis caused by nontraumatic CVJ abnormalities. The CVJ was examined in terms of atlanto-occipital angle, atlanto-axial angle, and lateral and anterior atlanto-dens intervals for the evaluation of occipital condylar hypoplasia, rotation of atlanto-axial joint, and lateral and anterior shift of the dens, respectively. Abnormalities of the lower cervical or thoracic spine were also evaluated. Occipital condylar hypoplasia, rotation of atlanto-axial joint, and lateral shift of the dens were the most common CVJ abnormalities. The 18.5% of the subjects had concurrent anomalies of lower cervical or thoracic vertebrae along with CVJ abnormalities. Each subject had 2.22 ± 1.10 types of CVJ abnormalities on average. In conclusion, comprehensive evaluation of CVJ abnormalities is recommended for differential diagnosis of subjects with unexplained torticollis. Once CVJ abnormalities are identified, concurrent abnormalities of other vertebrae need to be evaluated.

The occipital bone is a complex structure due to its anatomy and accessory sutures. Fracture - accessory suture differential diagnosis should be performed carefully in patients with a history of head trauma [4]. In this case report we wanted to emphasize that accessory sutures can be difficult to diagnose in patients with head trauma. We also specified the points to be considered in the suture - fracture differentional diagnosis. A bilateral, symmetrical fissure line was observed in the occipital bone basal part of the patient who was admitted to our emergency department due to head trauma. The patient was followed up with accessory suture and then discharged after paying attention to important points in the differential diagnosis., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Fusion of the atlas with the occipital bone is a rare congenital dysplasia known as occipitalization of the atlas, occipitocervical synostosis, assimilation of the atlas, or atlanto-occipital fusion. It is a component of the paraxial mesodermal maldevelopment and commonly associated with other dysplasias of the craniovertebral junction. External auditory canal atresia or external aural atresia is a rare congenital absence of the external auditory canal. It occurs as the consequence of the maldevelopment of the first pharyngeal cleft due to defects of cranial neural crest cells migration and/or differentiation. It is commonly associated with the dysplasias of the structures derived from the first and second pharyngeal arches including microtia. We present the coexistence of the occipitalization of the atlas and congenital aural atresia, an uncommon combination of the paraxial mesodermal maldevelopment, and defects of cranial neural crest cells. The association is most probably syndromic as minimal diagnostic criteria for the oculoariculovertebral spectrum are fulfilled. From the clinical point of view, it is important to be aware that patients with microtia must obtain also appropriate diagnostic imaging studies of the craniovetebral junction due to eventual concomitant occipitalization of the atlas and frequently associated C1-C2 instability.

Although proatlas segmentation abnormalities as developmental remnants around the foramen magnum have been reported in postmortem studies, they are rarely documented in a clinical setting. This report details the clinical and radiological characteristics of a rare case of proatlas segmentation abnormalities with clinical onset during the seventh decade of life. This case was suspected to have a familial factor. We also review the literature regarding this condition., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Traumatic aneurysms of the superficial temporal artery have been frequently reported in the literature, whereas traumatic aneurysms of the occipital artery (OA) are extremely rare., Case Description: A 30-year-old man had been followed at another hospital for meningoencephalocele associated with his congenital occipital bone defect. He was admitted to our hospital with a chief complaint of neck swelling and pain during a football game. Computed tomography and magnetic resonance imaging showed a hematoma in his right neck along with the meningoencephalocele. In addition, it showed an atrophic cerebellum with a cyst protruding from his occipital bone defect. Digital subtraction angiography of the right OA showed 3 aneurysms responsible for the large hematoma in his neck. Endovascular embolization with 20% N-butyl-2-cyanoacrylate was performed for treatment of the ruptured aneurysms followed by emergent surgical evacuation of the hematoma. An occipital cranioplasty with titanium mesh was performed 10 months after the emergent intervention., Conclusions: In this patient, the congenital occipital bone defect with meningoencephalocele might have been the remote source of risk for traumatic pseudoaneurysms along the muscle branches of the OA., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Case study description and analysis of a complex craniovertebral dysplasia in an 8-year-old male patient, in which conventional cervical spine radiographs demonstrated a regularly differentiated occipital base, as well as the presence of two lateral masses of the proatlas vertebra and two lateral masses of the atlas vertebra. Further assessment included computed tomography of the occipital base and the upper cervical spine as well as three-dimensional reconstruction. Malsegmentation of the fourth occipital vertebra can result in various anomalies that are known as 'manifestation of the proatlas'. The occurrence of a persistent proatlas with additional segmentation of the craniovertebral junction represents an extremely rare dysplasia. To our knowledge, it is the second report concerning the persistence of a complete human proatlas vertebra. We consider the biomechanical and embryological particularities of this complex dysplasia to represent sufficient basis for future differentiation from other malformations of the fourth occipital vertebra. Comprehensive literature review and discussion about the entity will be provided.

Study Design: Retrospective study., Objective: To investigate whether clivodens angle (CDA) could diagnose basilar invagination (BI) at computed tomography (CT)., Summary of Background Data: Over the years, multiple craniometric methods such as Chamberlain line, McGregor line, McRae line, Wackenheim clivus baseline, and Welcher basal angle have been described for evaluation of craniovertebral junction anomalies, initially with radiography and later with CT. However, such a variety of measurements in turn reflects the difficulty in making a definite diagnosis of BI and there is a certain disadvantage in all of these criteria because the anatomic landmarks vary within a normal range., Methods: CDA, described an angle formed at the intersetion of a line that runs along the long axis of the clivus and one that runs along the long axis of the dens, was measured on mid-sagittal reconstructed CT images from 63 BI patients and 100 control participants to compare the two groups by using independent-sample t test. Interobserver reliability was evaluated with Kendall correlation coefficient. For evaluating the diagnostic performance and determining the cutoff value of CDA, receiver operating characteristic curve was utilized., Results: The measurement of CDA showed good interobserver agreement (KCC = 0.891). Compared with control participants whose mean value was 135.8 degrees ± 9.2 (range, 118-156°), BI patients had a significantly smaller one (P < 0.001), 110.4 degrees ± 15.8 (range, 55-140°). The area under receiver operating characteristic curve was 0.937 (95% confidence interval: 0.901, 0.973), and the cutoff value of 125 degrees had the largest Youden index (J), 0.715., Conclusion: Having a better diagnostic performance than clivoaxial angle, CDA can be utilized for diagnosing BI., Level of Evidence: 3.

Objective: To characterize the phenotypes of spheno-occipital synchondrosis (SOS) in Chinese patients with Crouzon syndrome., Methods: Twelve patients with Crouzon syndrome were included in this retrospective study, and were divided into 2 groups. The first group included 5 patients (5-7-year old), whereas 7 patients were included in the second group (8-11-year old). Two age- and sex-matched control groups were constituted for comparison. All patients and controls were underwent preoperative computed tomography examinations of the craniofacial area, and the three-dimensional skull models, sagittal, and axial images were reconstructed. The density of the SOS region was also calculated., Results: The SOS was partially closed in the first Crouzon patients group, whereas the SOS was open in control groups. The SOS was completely fused SOS in the second Crouzon patients group, whereas the SOS was open or partially closed in control groups. There also were short and hypoplastic sphenoid bone in both Crouzon groups when compared with controls. In addition, the average density of SOS in patients with Crouzon syndrome was higher than the control groups (P <0.01)., Conclusions: The SOS begins to prematurely fuse in Chinese patients with Crouzon syndrome, and there are short and hypoplastic sphenoid bone in these patients. Although a definitive role of prematurely fused SOS in Crouzon syndrome cannot be drawn, our finds provide important clues into the mechanisms, and potentially provide a treatment target for midfacial and cranial vault hypoplasia in Crouzon patients.

Differentiation between accessory sutures and fractures in the skull of an infant can be difficult. Apart from the regular sutures there is a multitude of variations that may be mistaken for a fracture line. Such variations include for instance the intraparietal suture between the two ossification centers of the parietal bone or the mendosal suture between the supraoccipital and interparietal bone of the occipital squama. The presented case refers to an approximately 20-month-old female child. During autopsy, a discontinuity in the right paramedian posterior cranial fossa parallel to the internal occipital crest with connection to the foramen magnum was observed. The macroscopic findings suggested a fracture line because of its course. However, neither a hemorrhage in the soft tissue nor callus formation was discernible. The discontinuity was preserved with the adjacent parts of the occipital bone for further histological examination. In the report of a cranial CT, which was carried out five days before the child's death, an accessory suture paramedially in the right posterior cranial fossa was described. When the clinical CT records were re-evaluated, a similar discontinuity at the corresponding position on the other side was detected, though of noticeably shorter length. Additionally, the preserved occipital bone fragment including the discontinuity was histologically processed. In the radiological literature, precise (radiological) criteria for differential diagnosis are indicated. A zigzag pattern with sclerotic borders and a bilateral and fairly symmetric occurrence indicate a suture, whereas a sharp lucency with non-sclerotic edges and a unilateral occurrence indicate a fracture. Taking all the findings into account, the depicted discontinuity was regarded as an accessory suture. This case demonstrates that differentiation between a fracture and an accessory suture may be difficult in the autopsy of a child and underlines the importance of a postmortem CT examination.

An encephalocele is a protrusion of the brain and/or meninges through a defect in the skull. Based on the location of the skull defect they are classified into sincipital, basal, occipital or parietal varieties. Occurrence of more than one Encephalocele in a patient is very rare and very few cases of double encephalocele are reported. We report an interesting case where a parietal and an occipital encephalocele were present together. The patient was a 2 months boy who was brought to us with complaints of two swelling on the scalp since birth. Neuroimaging studies confirmed it to be a case of double encephalocele. The rarity of the findings prompted us to report this case. The presentation and management of the case along with and review of the relevant literature is presented., (Copyright © 2016 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Purpose: To describe the clinical and radiological characteristics of uncommon upper cervical spine abnormality in children., Methods: Clinical and diagnostic characteristics of three patients aged 6-12 years with a similar uncommon type of occipital anomaly are described. The patients were admitted in 2007, 2009, and 2014, respectively., Results: All patients were clinically and radiologically examined. In each case the massive, additional unilateral outgrowth of the occipital bone (os occipitale) was visualized. The signs and symptoms included torticollis, acute brain ischemia, and limited head motion. Two of the three patients underwent surgical treatment: an occipital-cervical fusion was performed in the first patient, and the outgrowth was removed in the second patient. After 1 year of follow-up the results were estimated as good for both patients, with better functional outcome for the second patient. The parents of the third patient did not consent for the surgical treatment., Conclusions: The unique features of this abnormality distinguish it from previous descriptions of the manifestation of pro-atlas, atlas, or atlanto-occipital synostosis. The presented abnormality had different manifestation of various severity in each case, from torticollis to acute vascular disorder., Study Design: Clinical case series., Level of Evidence: IV.

Cranio-vertebral junction is a pivot which holds the globe of the head. Bony anomalies at this point are particularly significant because they lodge the spinal cord and lower part of the brain stem. Clinically fusion of the atlas with the lower part of the occiput is known as Atlanto-occipital assimilation or atlas occipitalization, which can be either partial or complete depending upon the extent of fusion. It can present as totally asymptomatic accidental finding or can be a cause behind major neuro-vascular compression. The present case study is an endeavor to explain occipitalization of atlas bone on the basis of embryology and explain its clinical relevance.

Background: Klippel-Feil syndrome (KFS) is characterized by congenital vertebral fusion of the cervical spine and a wide spectrum of associated anomalies. In patients with KFS with basilar invagination (BI), compression of the brainstem and upper cervical cord results in neurological deficits, and decompression and occipitocervical reconstruction are required. The highly varied anatomy of KFS makes a posterior occipitocervical fixation strategy challenging. For these patients, the transoral atlantoaxial reduction plate (TARP) operation is an optimal option to perform a direct anterior fixation to achieve stabilization., Objective: To evaluate the effectiveness of TARP internal fixation for the treatment of BI with KFS., Methods: Ten consecutive patients with BI and KFS who underwent TARP reduction and fixation from 2010 to 2012 were reviewed. Clinical assessment and image measurements were performed preoperatively and at the most recent follow-up. Nine patients (9/10) were followed for an average of 31.44 months., Results: Symptoms were alleviated in 9 of 9 patients (100.00%). The odontoid process was ideally corrected with the TARP system. The mean clivus canal angle improved from 124° preoperatively to 152° postoperatively. The average preoperative and postoperative Japanese Orthopedic Association scores were 10.56 (n = 9) and 14.67 (n = 9), respectively, indicating 63.82% improvement. There was bony bridge catenation on the computed tomography scans and no evidence of hardware failure at 6 months., Conclusion: The TARP operation is effective and safe for treating patients with BI with KFS. The midterm clinical results were satisfactory.

Introduction: The formation of the occipital bone is intricate and has been extensively studied with many controversial conclusions, but with minimal effort being focused on the genes and molecular interactions necessary for its formation. A better understanding of this bone of the calvarial and skull base may shed light on pathologies where the occiput is often considered the offending entity., Methods: A review of the germane medical literature using textbooks and standard search engines was performed to gather information about previous conclusions as it pertains to the embryology and ossification of the occipital bone., Results: The occipital bone has both membranous and cartilaginous origin with ossification occurring as early as week 9 of fetal gestation. Its formations is dependent on complex interacts between genes and molecules with pathologies resulting from disruption of this delicate process., Conclusion: There has been much controversy in the past in regards to the development and ossification process necessary for occipital bone formation, which has only recently been clarified with documentation of the genes and molecular interactions necessary for its formation. Lastly, this improved knowledge might improve our understanding of such congenital derailments as the Chiari malformations.

Object: Craniosynostosis syndromes are characterized by prematurely fused skull sutures, however, less is known about skull base synchondroses. This study evaluates how foramen magnum (FM) size, and closure of its intra-occipital synchondroses (IOS) differ between patients with different craniosynostosis syndromes and control subjects; and whether this correlates to ventriculomegaly and/or Chiari malformation type I (CMI), intracranial disturbances often described in these patients., Methods: Surface area and anterior-posterior (A-P) diameter were measured in 175 3D-CT scans of 113 craniosynostosis patients, and in 53 controls (0-10 years old). Scans were aligned in a 3D multiplane-platform. The frontal and occipital horn ratio was used as an indicator of ventricular volume, and the occurrence of CMI was recorded. Synchondroses were studied in scans with a slice thickness ≤1.25 mm. A generalized linear mixed model and a repeated measures ordinal logistic regression model were used to study differences., Results: At birth, patients with craniosynostosis syndromes have a smaller FM than controls (p < 0.05). This is not related to the presence of CMI (p = 0.36). In Crouzon-Pfeiffer patients the anterior and posterior IOS fused prematurely (p < 0.01), and in Apert patients only the posterior IOS fused prematurely (p = 0.028)., Conclusion: The FM is smaller in patients with craniosynostosis syndromes than in controls, and is already smaller at birth. In addition to the timing of IOS closure, other factors may influence FM size., (Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Isolated unilateral frontosphenoidal synostosis is a rare and often misdiagnosed cause of synostotic frontal plagiocephaly. It is important to distinguish the various synostotic causes of frontal plagiocephaly from deformational frontal plagiocephaly because operative intervention is required in synostotic plagiocephaly to avoid progressive deformity, whereas deformational plagiocephaly typically improves without surgery. This study reports a patient with a unique case of anterior plagiocephaly caused by left-sided frontosphenoidal craniosynostosis. The workup should include a thorough history and clinical examination followed by computed tomography scan with three-dimensional reconstruction. Frontosphenoidal synostosis should be suspected in the absence of a coronal synostosis in a child with anterior unilateral plagiocephaly and treated surgically. Good aesthetic and functional results occur with prompt diagnosis and early surgical correction.

Introduction: It is widely accepted that there is a relationship between the cranial base and the development of the nasomaxillary complex (NMC). The objective of the present study was to investigate the morphological relationship between these two anatomical units in skulls that have intentionally been subjected to one of two types of artificial deformity of the cranial vault [artificially deformed skulls (ADS)]., Material and Methods: A geometric morphometry study was performed on lateral cephalometric X-rays of three groups of crania: 32 with anteroposterior (AP) deformity, 17 with circumferential (C) deformity, and 39 with no apparent deformity., Results: The cranial base of the ADS showed marked deformity that produced a restriction of AP growth of the NMC, alterations of the roof of the orbit as a consequence of the rotation of anterior cranial fossa, and nasal protrusion. Pronounced morphological differences were found between the three groups: increased vertical development of the maxilla occurred in both ADS groups due to growth of the alveolar process, and rotation of the maxilla and displacement of the orbital rim was observed in the C group. This confirms that the posterior facial plane is regarded as an axial structure that serves as an interface between the middle cranial base and the NMC (Enlow, D.H. and Hans, M.G. (1996) Essential of Facial Growth. WB Saunders Co., Philadelphia, PA)., Limitations: It is important to take into account that these results have been obtained from an archaeological sample, with all the limitations that this implies such as being a small sample and with no absolute certainty regarding the use of the same type of deforming device within each group. Furthermore, this is a lateral two-dimensional study in which transverse development has not been analysed., Conclusions: Artificial modification of the shape of the vault has repercussions on the NMC that support the theory of an all-inclusive integration of the different cranial units in normal as well as in restricted development., (© The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

A subset of patients with Chiari Type I malformation may develop neurological dysfunction secondary to an abnormally obtuse clivoaxial angle (CXA) and clivoaxial deformity causing deformative stress injury to the neural axis. Clivoaxial deformity can occur after initial standard suboccipital craniectomy, duraplasty, and C-1 laminectomy for brainstem compression, or severe clivoaxial deformity may be present in conjunction with a Chiari malformation. Clivoaxial deformity and abnormal CXA can be treated with an occipitocervical fusion (OCF). Performing OCF in the setting of a cranial defect can be challenging with currently available instrumentation. The authors describe their recent experience and outcomes in 3 consecutive pediatric patients using the "inside-out" technique for treating clivoaxial deformity and abnormal CXA in the setting of a craniectomy defect to restore stability to the craniocervical junction, while correcting the CXA.

Purpose: Congenital craniocervical segmentation anomaly associated with malalignment of the odontoid process causes progressive spinal cord compression with myelopathy. Recent literatures have reported that ventral decompression could be achieved with posterior craniocervical realignment through posterior instrumented reduction. The purpose of the present study is to show the efficacy of intraoperative electrophysiological monitoring during craniocervical realignment through screws and rod system for congenital craniocervical segmentation anomaly., Methods: Consecutive ten patients with a congenital craniocervical segmentation anomaly and myelopathy due to a malaligned odontoid process, who underwent posterior craniocervical realignment, were included. Klippel-Feil syndrome (KFS) was combined in four patients. Gait disturbance and motor weakness were the main presentation. Craniocervical realignment was achieved by intraoperative distraction through a rod and screw system. Intraoperative neuromonitoring was performed with transcranial motor-evoked potential (TcMEP) and somatosensory-evoked potential (SSEP)., Results: Significant change in TcMEP occurred in two patients with KFS during surgery, but the change was reversed with release of distraction. All patients were awakened without neurological deficit. Motor weakness and gait disturbance were normalized within 6 months in all patients. Postoperative computed tomography scan and/or magnetic resonance imaging showed that the reduction was complete in all patients., Conclusions: Craniocervical realignment through screws and rod system may be safe and efficacious surgical technique for the treatment of congenital craniocervical anomaly with the help of intraoperative neuromonitoring. However, distraction should be cautiously monitored, especially when Klippel-Feil syndrome is combined.

Objective: We defined parameters that could differentiate between positional and synostotic plagiocephaly and defined a diagnostic chart for decision making., Design: Prospective study., Setting: We examined 411 children with non-syndromic skull abnormalities between January 2011 and December 2012., Participants: A total of 8 infants under 1 year of age with proven unilateral non-syndromic lambdoid synostosis (LS) and 261 children with positional deformity were examined to outline the specific clinical features of both diagnoses. After clinical examination, an ultrasound revealed either a closed suture suggestive of LS or a patent lambdoid suture suggestive of positional deformity. For patients with synostosis, plain radiographs, MR imaging and follow-up examinations were performed. In cases of open sutures, only follow-ups were completed., Main Outcome Measure: Clinical, imaging, genesis and treatment differences between positional plagiocephaly and LS., Results: In all 8 cases of unilateral LS and 258 cases of positional plagiocephaly, the diagnosis was established by clinical examination alone. In three cases of positional plagiocephaly, diagnosis was determined after an additional ultrasonography. MR imaging revealed a unilateral tonsillar herniation in five of the eight children with LS and hydrocephalus in one child., Conclusions: We have suggested a list of clinical features that specify the underlying cause of posterior plagiocephaly. An additional ultrasound scanning confirmed the diagnosis without any risks of ionising radiation or sedation as in a CT scan., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

The ocular and systemic abnormalities of nonsyndromic craniosynostosis are often considered to be less severe than those of syndromic craniosynostosis and are less well described. The purpose of this article was to describe the frequency and nature of ophthalmic abnormalities in children treated for nonsyndromic craniosynostosis by expansion cranioplasty. A retrospective review identified 88 consecutive children with nonsyndromic craniosynostosis who underwent expansion cranioplasty with distraction osteogenesis. Assessment of presence and type of strabismus, refractive error, and amblyopia before and 6 months after surgery was recorded. Children with a mean age of 24.4 months were treated for nonsyndromic craniosynostosis (27 with coronal and 61 with sagittal and/or lambdoid). One-fourth of the patients had a fixation preference. Significant refractive errors were found in 45 (51%) of the 88 patients: hyperopia in 27%, myopia in 5%, and astigmatism in 35%. Anisometropia was present in 20%. Of the 85 patients who completed orthoptic examination, 48 (56%) had strabismus: exodeviation in 26%, esodeviation in 14%, and vertical deviation in 5%. Fourteen patients (16%) had abnormal head posture. Significant refractive error and strabismus were more likely to occur in cases with coronal synostosis. The procedures used for cranial vault expansion improved the abnormal head posture but did not affect the refractive error or ocular misalignment. Of children with nonsyndromic craniosynostosis who need neurosurgical correction, more than half were found to have significant refractive error and strabismus. Our findings support the importance of ophthalmic evaluation in these children.

Background: Structural anomaly of the cervical spine or craniocervical junction has been reported as one of the rare causes of ischemic stroke. We report a case of a young patient with recurrent posterior circulation infarction that may have been associated with an anomalous occipital bony process compressing the vertebral artery., Case Presentation: A 23-year-old man experienced recurrent posterior circulation infarction 5 times over a period of 5 years. He had no conventional vascular risk factors. Young age stroke work-up including thorough cardiac, intra- and extracranial vascular evaluation and laboratory tests for the hypercoagulable state or connective tissue disease yielded unremarkable results. An anomalous bony process from the occipital base compressing the left vertebral artery was observed on brain CT. All the recurrent strokes were explainable by the arterial thromboembolism originating from the compressed left vertebral artery. Therefore, the left vertebral artery compressed by the anomalous occipital bony process may have been the culprit behind the recurrent thromboembolic strokes in our patient. Intractable recurrent strokes even under optimal medical treatment led us to make a decision for the intervention. Instead of surgical removal of the anomalous occipital bony process, the left vertebral artery was occluded permanently by endovascular coiling after confirming that this would cause no neurological deficits or flow disturbance in the posterior circulation. There was no recurrence of stroke for 2 years after permanent occlusion of the left vertebral artery., Conclusion: Arterial thromboembolism originating from the left vertebral artery compressed by the anomalous occipital bony process is a rare but not to be overlooked cause of posterior circulation infarction. When intractable to medical treatment, endovascular occlusion of the vertebral artery without flow disturbance to the posterior circulation may be a useful treatment option when surgical removal is not feasible.

A case of atlas assimilation revealed during serial study of suboccipital region is presented. The specimen was harvested from the body of 31-year-old woman. Images of the computed tomography scans are correlated with classic dissection. Asymmetrical bony assimilation is accompanied by asymmetrical development of the suboccipital musculature. In the presented case, the atlantic segments of both vertebral arteries preserved their usual course between bony elements derived from the atlas and proatlas. Development of the soft tissues must be influenced by similar factors as development of the skeleton. Detailed radiologic studies, possibly with volumetric reconstructions, are necessary in cases of atlas assimilation before surgical interventions in the region of craniovertebral junction.