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Occipital condylar avulsion fractures are considered potentially unstable, associated with craniocervical dissociation spectrum injuries, and thought to carry a relatively high mortality rate based on the current literature. The purpose of this study was to identify patient with acute, occipital condylar avulsion fractures and evaluate for the incidence of concomitant cervical osteoligamentous trauma and craniocervical dissociation spectrum injury on cervical spine CT and MRI. Patients who suffered an inferomedial occipital condylar avulsion fracture were identified retrospectively using Nuance mPower software. Cervical spine CT and MRI reports performed within 48 h for this patient cohort were then reviewed by two CAQ certified neuroradiologists. Confirmation of an occipital condylar avulsion fracture was recorded along with any concomitant craniocervical junction injury. Relevant clinical history, including management and outcomes, was recorded for each patient. Thirty-four patients were identified with an inferomedial fracture of the occipital condyle. Of the 85% of patients who underwent cervical MRI, all but one patient demonstrated a ‘negative’ MRI without major craniocervical junction ligamentous injury. These patients were treated conservatively with external bracing without persistent neurologic deficits upon 4-month follow-up. Inferomedial fractures of the occipital condyle are currently classified as potentially unstable fractures based on the Anderson classification system. Our data suggest that an isolated occipital condylar avulsion fracture without an additional C1–C2 fracture or widening of the atlanto-occipital joint space is likely a stable injury that can be treated conservatively with excellent clinical outcomes.

Background The Chihuahua dog breed is known for frequent occurrence of a bregmatic fontanelle on the dorsal skull. A common conception is that this skull defect is a clinically irrelevant finding. No studies, however, describe its prevalence or whether it is accompanied by other persistent fontanelles (PFs). Although Chihuahuas are predisposed to Chiari-like malformation (CM) and syringomyelia (SM), it is unknown whether PFs occur more commonly in dogs with clinical signs that are caused by CM or SM. Hypothesis/objectives To describe the number and location of PFs at cranial sutures (CSs) and to compare the occurrence of these PFs in dogs with and without CM/SM-related clinical signs. We hypothesized that PFs also occur commonly at lateral and caudal cranial surfaces, affect a higher number of CSs, and are larger in dogs with CM/SM-related clinical signs. Animals Fifty client-owned Chihuahuas with or without CM/SM-related clinical signs. Results Of the 50 dogs evaluated, 46 (92%) had either 1 or several PFs. The mean ± SD number of PFs was 2.8 ± 3.0 (range, 0-13). A total of 138 PFs occupied 118 CSs with 57 (48%) located dorsally, 44 (37%) caudally, and 17 (14%) laterally. The number of CSs affected by PFs was significantly higher (P ≤ .001) and total PF area was significantly larger (P = .003) in dogs with CM/SM-related clinical signs. Conclusions and clinical importance Persistent fontanelles are very common in this group of Chihuahuas and appear at dorsal, lateral, and caudal cranial surfaces. They are more numerous and larger in Chihuahuas with CM/SM-related clinical signs.

Background Persistent fontanelles (PFs) are, in Chihuahuas, almost ubiquitous. Furthermore, Chihuahuas are predisposed to other craniomorphological abnormalities, including syringomyelia (SM), ventriculomegaly, and craniocervical junction (CCJ) overcrowding resulting in neural tissue deviation. It is, however, undetermined if PFs are more common in dogs with these structural abnormalities, and their etiology is unknown. Hypothesis/objectives Persistent fontanelles are more numerous and larger in Chihuahuas with low body weight, older age, SM, dilated fourth ventricle, ventriculomegaly, and CCJ overcrowding. Animals Fifty client-owned Chihuahuas. Methods Cross-sectional study evaluating the association of both the number of cranial sutures affected by PFs (NAS) and total fontanelle area (TFA), based on computed tomography with SM, fourth ventricle dilatation, lateral ventricle volume, and extent of neural tissue compression at the CCJ based on magnetic resonance images. Results The NASs was higher and TFA larger in dogs with low body weight (NAS: P = .007; 95% confidence interval [CI] = 0.384-0.861; TFA: P = .002; 95% CI = -1.91 to -0.478), larger lateral ventricles (NAS: P ≤ .001; 95% CI = 1.04-1.15; TFA: P ≤ .001; 95% CI = 0.099-0.363), and more severe neural tissue compression at the CCJ (NAS: P ≤ .001; 95% CI = 1.26-2.06; TFA: P = .03; 95% CI = 0.066-1.13). Similarly, dogs with SM (NAS: P = .004; 95% CI = 1.26-3.32; TFA: mean ± SD, 130 ± 217 mm2 ; P = .05) had higher NAS and larger TFA than did dogs without SM (43.7 ± 61.0 mm2 ). Age was not associated with NAS (P = .81; 95% CI = 0.989-1.01) or TFA (P = .33; 95% CI = -0.269 to 0.092). Conclusions and clinical importance Persistent fontanelles are associated with small size, SM, ventriculomegaly, and CCJ overcrowding.

Duplication of the odontoid process remains a rare developmental pathology that is underrepresented in the current literature. As the pivot point for the craniovertebral junction, the odontoid process is vital for the integrity of the atlanto-axial joint and the ability of the head and cervical spine to rotate correctly. The pathogenesis being incompletely understood, it has been proposed that odontoid process duplication involves faulty sclerotome migration and disruption of the axis ossification center. Patients presenting with this pathology usually have associated structural abnormalities. A detailed anatomical and embryological understanding of the odontoid process is necessary for successful management and treatment of patients presenting with odontoid process duplication. We present a rare case of a patient with a duplicated odontoid process in association with C2–C3 fusion, incomplete anterior arch of C1, variant inferior bony process of the transverse process of C1, and enlarged right jugular foramen.

Neurenteric cysts are rare congenital lesions of benign nature that can be encountered at any level of the neuraxis, starting from the cranium down to coccyx. Rewarding outcome can be achieved with early diagnosis and complete removal of these benign lesions. Here, we report a case of a huge neurenteric cyst in an 11-year-old boy at the ventral craniocervical junction, a rarely reported entity with literature review. In this article, we focus on the clinical presentation, pathogenesis, radiological findings, surgery, and surgical outcome of this benign lesion, as we succeeded to have gratifying result following surgery in our instance.

Background Long-term stabilization of the cervical spine after extensive multilevel tumor resection is difficult to achieve. The current standard approach of instrumentation combined with allograft or nonvascularized autograft is limited in settings of increased risk of nonunion or delayed union (i.e., prior radiation therapy or poorly vascularized wound beds). Case Description We report the first time to our knowledge that a vascularized fibular free flap has been used to reconstruct the cervical column across 5 vertebral levels, from the craniocervical junction to the lower cervical spine. We describe a transoral approach to the area and compare this method with other reconstructive options. Conclusions Vascularized bone grafting is a viable alternative to achieve lasting stability because of hastened fusion time, limited reliance on osseous remodeling, and incorporation into the axial skeleton with strut strength.

Horizontal fractures of the atlas are uncommon fractures associated with instability of the craniocervical junction. Most commonly associated with high-speed motor vehicle accidents, these fractures need to be identified and treated appropriately. Due to its relatively benign presentation on bony imaging, magnetic resonance imaging to look for ligamentous instability is important. We present two such cases which were managed by occipitocervical fusion at our institute.

To assess the accuracy of craniocervical measurements for identifying craniocervical injuries and the frequency of subjective findings of craniocervical injuries on CT in pediatric patients. Case-controlled retrospective review of patients ≤ 16 years old with craniocervical junction injuries. Receiver operator curves were created for common craniocervical measurements on CT comparing patients with complete and partial craniocervical injuries to uninjured cohort. Frequency of subjective CT findings of craniocervical injury was assessed in the injured cohort. For complete disruption injuries (CD) (n = 27), C1–C2 distance (AUC = 0.90, 95%CI = 0.83–0.97), atlanto-occipital distance (AUC = 0.95–0.98, 95%CI = 0.90–1.00), and basion-dens distance (AUC = 0.90, 95%CI = 0.82–0.98) had excellent accuracy diagnosing injury. Powers ratio (AUC = 0.85, 95%CI = 0.76–0.94) had good, basion-posterior axial line (AUC = 0.74, 95%CI = 0.61–0.86) fair, and atlanto-dental distance (AUC = 0.69, 95%CI = 0.57–0.82) poor accuracy. For partial disruption injuries (PD) (n = 21), basion-dens distance (AUC = 0.75, 95%CI = 0.62–0.88) had fair accuracy diagnosing injury. Powers ratio (AUC = 0.63, 95%CI = 0.47–0.79), C1–C2 distance (AUC = 0.60, 95%CI = 0.45–0.75), atlanto-dental distance (AUC = 0.55, 95%CI = 0.39 = 0.71), atlanto-occipital distance (AUC = 0.63–0.65, 95%CI = 0.47–0.81), and basion-posterior axial line (AUC = 0.60, 95%CI = 0.44–0.76) all had poor accuracy. Eighty-one percent (n = 22) of CD and 38% (n = 8) of PD patients had non-concentric atlanto-occipital joints. One hundred percent of CD patients had ≥ 1 soft tissue finding and eighty-one percent (n = 22) had ≥ 2 findings. Seventy-three percent (n = 16) of PD patients had ≥ 1 soft tissue finding. Eighty-six percent (n = 18) of PD patients had non-concentric atlanto-occipital joints and/or soft tissue findings. Craniocervical measurements have poor accuracy for identifying craniocervical injuries in pediatric patients with incomplete craniocervical ligament disruption. Subjective findings of craniocervical injury are frequently present on CT in pediatric patients and can help increase sensitivity for identifying injury.

Study Design: In vitro biomechanical study. Objective: The strength of the alar ligament has been described inconsistently, possibly because of the nonphysiological biomechanical testing models, and the inability to test the ligament with both attachments simultaneously. The purpose of this biomechanical model was to reevaluate the alar ligament’s tensile strength with both bony attachments, while also keeping the transverse ligament intact, all in a more physiological biomechanical model that mimics the mechanism of traumatic injury closely. Methods: Eleven fresh-frozen occipito-atlanto-axial (C0-C1-C2) specimens were harvested from individuals whose mean age at death was 77.4 years (range 46-97 years). Only the alar and transverse ligaments were preserved, and the bony C0-C1-C2 complex was left intact. Axial tension was exerted on the dens to displace it posteriorly, while the occipito-axial complex was fixed anteriorly. A device that applies controlled increasing force was used to test the tensile strength (M2-200, Mark-10 Corporation). Results: The mean force required for the alar ligament to fail was 394 ± 52 N (range 317-503 N). However, both the right and left alar ligaments ruptured simultaneously in 10 specimens. The ligament failed most often at the dens (n = 10), followed by occipital condyle rupture (n = 1). The transverse ligament remained intact in all specimens. Conclusions: When both the right and left alar ligament were included, the total alar ligament failure occurred at an average force of 394 N. The alar ligament failed before the transverse ligament.

Care should be taken regarding surrounding anatomic structures during access to deep-seated extracranial schwannomas in the craniocervical junction (CCJ). Herein, we present surgical tips for extracranial schwannomas in the CCJ using the anterolateral approach. A retrospective review was performed of 3 cases of surgical treatment of extracranial schwannomas in the CCJ by the anterolateral approach, which is a presternomastoid retrojugular route to the CCJ. The combination of neck rotation and reflection of the sternocleidomastoid muscle presented a sufficient, shallow surgical field for the CCJ. We could identify tumors along the accessory nerves and internal jugular veins, and had sufficient rostrocaudal working space to resect the tumors. Two cases were enucleated total resection and 1 was subtotal resection. Two patients experienced transient postoperative vocal cord partial paralysis and 1 had transient dysphagia. These neurological complications improved within 1 month. The anterolateral approach can provide a shallow and sufficient rostral and caudal surgical window.

The embryonic occipital bone and odontoid process of the axis are attached and connected by the notochord, but become separated in later development and growth. With special attention to the process of separation, we examined sagittal sections of the craniocervical junction in 18 human fetuses at 8-16 weeks and 22 fetuses at 31-37 weeks. At 8-9 weeks, the anterior arch of atlas was always seen overriding the occipital basal part. The odontoid process was close to the occipital with or without a transient joint cavity until 16 weeks. Near term, the top of the odontoid process was usually higher than the anterior arch, but the former was sometimes (7 of 22) at a level almost equal to or lower than the latter. The apical ligament was evident in a few specimens (5 of 22). A distance between the occipital basion and odontoid process was sometimes less than 1.5 mm (8 of 22) or less than half the thickness of the arch (10 of 22). A transient joint cavity between the basion and odontoid process was often (10 of 22). In three fetuses near term, the atlanto-occipital joint cavity was continuous with the median atlanto-axial joint cavity, and the anterior arch was overriding the occipital basal part. Therefore, rather than stage or age, individual differences were evident in the topographical relationship between the three bony elements at the craniocervical junction. An understanding of the embryology and normal development will aid in the correct interpretation of radiologic images of the pediatric cervical spine.

SUMMARY INTRODUCTION Retro-odontoid pseudotumor (ROP) is a rare disease that affects the atlantoaxial joint and, in general, is associated with local biomechanical alterations that may or may not cause instability. METHODS Descriptive study of the literature available in databases MEDLINE/PubMed, LILACS, and Scopus. The research was conducted in April 2019. DISCUSSION ROP is, possibly, a syndromic designation that encompasses a significant variety of diseases of the atlantoaxial joint. There are different pathophysiological mechanisms implicated in its genesis. The patients, almost in their entirety, present with severe myelopathy, and most of them are treated surgically, with the posterior decompression being the most commonly used method, with or without arthrodesis. Evolution is usually favorable. CONCLUSION The ROP is still poorly recognized as a differential diagnosis between the diseases of the cranial-cervical junction. The information available in the literature analyzed was based mainly on the study of reports or case series; therefore, it is insufficient to define conducts with a high level of scientific evidence.

Background Following head and neck trauma, the involvement of the cranio-cervical junction (CCJ) and its contribution to a patients transition to chronic pain, is poorly understood. The detection of hypermobility in this region is dependent on clinical examination and static imaging modalities such as x-ray, CT and MRI. Sagittal plane hypermobility of the CCJ is evaluated using saggital view, flexion-extension cervical radiographs. Frontal plane hypermobility is typically assessed using lateral bending and open mouth cervical radiographs. Unfortunately there is no established reliability surrounding the use of these measures. This study explores the reliability of radiographic measurements of lateral-bending open-mouth cervical radiographs. Methods Cervical open-mouth lateral-bending X-ray images were collected from 56 different patients between 18 and 60 years of age patients following cervical spine injury. These images were interpreted by two musculoskeletal radiologists and two clinicians (physiatrist and chiropractor), using a standard set of measurements. Measurements included qualitative and quantitative assessments of the amount of asymmetry noted between various osseous landmarks. Reliability statistics were calculated for levels of agreement using kappa coefficients (κ) and Intraclass Correlation Coefficients (ICC) for dichotomous and continuous variables, respectively. Results Reliability (κ) for qualitative assessments were moderate to substantial for asymmetry of neutral C2 spinous position, dens-lateral mass spacing, and “step off” between the lateral borders of the articular pillars of C2 and C1 lateral mass (κ range = .47–.78). ICC values for the quantitative measurements of dens-lateral mass spacing and “step off” between the lateral borders of the C2 articular pillars and C1 lateral mass were moderate to excellent (ICC range = .56–.97). Conclusions The qualitative and quantitative measurements used in this study demonstrated good to excellent inter-examiner reliability. Correlation with clinical findings is necessary to establish the utility of these measurements in clinical practice.

Much controversy remains on the current management of Chiari I deformity (CID) in children, with many clinical, surgical and ethic-legal implications. The Brazilian Society of Pediatric Neurosurgery (SBNPed, in the Portuguese acronym) has put together a panel of experts to analyze updated published data on the medical literature about this matter and come up with several recommendations for pediatric neurosurgeons and allied health professionals when dealing with CID. Their conclusions are reported herein, along with the respective scientific background.

Study Design: In vitro biomechanical study. Objective: The transverse ligament is the strongest ligament of the craniocervical junction and plays a critical role in atlanto-axial stability. The goal of this cadaveric study, and the subsequent study (part II), was to reevaluate the force required for the transverse ligament and alar ligament to fail in a more physiological biomechanical model in elderly specimens. Methods: Twelve C1-2 specimens were harvested from fresh-frozen Caucasian cadavers with a mean age at death of 81 years (range 68-89 years). Only the transverse ligament was preserved, and the bony C1-2 complex was left intact. The dens was pulled away from the anterior arch of C1 using a strength test machine that applies controlled increasing force. After testing, the axis was split in half to check for hidden pathologies and osteoporosis. The differences in the failure force between sex and age groups (group 1: 80 years) were compared. Results: The mean force required for the transverse ligament to fail was 236.2 ± 66 N (range 132-326 N). All but 2 specimens had significant osteoporotic loss of trabecular bone. No significant differences between sex and age groups were found. Conclusions: The transverse ligament’s failure in elderly specimens occurred at an average force of 236 N, which was lower than that reported in the previous literature. The ligament’s failure force in younger patients differs and may be similar to the findings published to date.

Stability of the upper cervical spine is highly dependent on ligaments and membranes. These are best appreciated on magnetic resonance imaging (MRI), which can reveal damage to these structures in traumatic, congenital, infectious, and inflammatory conditions. It can also be used to evaluate the spinal cord and spinal canal to assess neurologic compression and cord pathology. Given the potential for devastating neurologic consequences in the setting of upper cervical instability and neural structure compression or injury, MRI is an invaluable tool for evaluation of the craniocervical junction.

Chordomas are histologically benign tumors with local aggressive behavior. They arise from embryological remnants of the notochord at the clivus, mobile spine, and sacrum. Chordomas are rare tumors in the pediatric age group. Their surgical management is difficult, given their propensity for inaccessible anatomical regions, and proximity to critical neurovascular structures. While en bloc resection with surgical margins has been advocated as the preferred approach for chordomas, tumor characteristics and violation of adjacent anatomical boundaries may not allow for safe en bloc resection of the tumor. Here, the authors present the case of a C1 chordoma in a 5-year-old boy with epidural and prevertebral extension. The patient’s treatment consisted of a far-lateral approach for resection of the tumor and C1 arch, followed by circumferential reconstruction of the craniocervical junction with an expandable cage spanning the skull base to C2, and posterior occipitocervical spinal instrumentation. At 42 months after surgery, the patient remains neurologically intact with stable oncological status, and no evidence of craniocervical junction instrumentation failure.

Intradural spinal lipomas are rare in an adult population. They are mostly asymptomatic and usually associated with spinal dysraphism in a pediatric population. We report a rare case of spinal lipoma without dysraphism and with progressing hemiparesis. A 60-year-old woman had incidental lipoma at the craniocervical junction observed for more than 5 years. Recently, she developed right-sided hemiparesis and sensory disturbance. Radiological studies revealed a large lipoma compressing the dorsal medulla and C1–C2 spinal cord. Standard midline suboccipital craniotomy and C1 laminectomy were performed, and the lipoma was removed subtotally. The lipoma showed severe adhesion to the dorsal medulla and C1 spinal cord; therefore, the excision was limited as internal debulking. Her neurological deficit subsided within 6 months after the decompressive surgery. Considering the benign nature of lipoma, internal decompression is a reasonable management for this lesion.

Metastases involving the clivus and craniocervical junction (CCJ) are extremely rare. Skull base involvement can result in cranial nerve palsies, while an extensive CCJ involvement can lead to spinal instability. We describe an unusual case of clival and CCJ metastases presenting with VI cranial nerve palsy and neck pain secondary to CCJ instability from metastatic bladder urothelial carcinoma. The patient was first treated with an endoscopic endonasal approach to the clivus for decompression of the VI cranial nerve and then with occipitocervical fixation and fusion to treat CCJ instability. At the 6-month follow-up, the patient experienced complete recovery of VI cranial nerve palsy. To the best of our knowledge, the simultaneous involvement of the clivus and the CCJ due to metastatic bladder carcinoma has never been reported in the literature. Another peculiarity of this case was the presence of both VI cranial nerve deficit and spinal instability. For this reason, the choice of treatment and timing were challenging. In fact, in case of no neurological deficit and spinal stability, palliative chemo- and radiotherapy are usually indicated. In our patient, the presence of progressive diplopia due to VI cranial nerve palsy required an emergent surgical decompression. In this scenario, the extended endoscopic endonasal approach was chosen as a minimally invasive approach to decompress the VI cranial nerve. Posterior occipitocervical stabilization is highly effective in avoiding patient’s neck pain and spinal instability, representing the approach of choice.

Introduction: The superficial anterior atlanto-occipital ligament (SAAOL) is a narrowband located anterior to the anterior atlanto-occipital membrane. Nearly forgotten, it has not been well described in older anatomical textbooks and is missing in the current anatomical literature. As all of the binding structures of the craniocervical junction (CCJ) are important in maintaining stability, this study aims to clarify the anatomy and potential function of the SAAOL. Materials and Methods: The CCJ from ten fresh-frozen cadavers was studied. These specimens were derived from three males and seven females, and the age at death ranged from 57 to 91 years (mean, 79.8 years). The length, width, and thickness of the SAAOL were measured. In five specimens, the force to failure was recorded. Results: The SAAOL was found between the anterior tubercle of the atlas and the occiput and located as central thick fibers in front of the anterior atlanto-occipital membrane in 9 (90%) specimens. In one specimen, the vertical band to the occipital bone did not attach to the anterior tubercle of the atlas, but extended to the anterior aspect of the axis. The mean length, width, and thickness of the SAAOL were 19.8, 6.2, and 0.6 mm, respectively. The force to failure for the ligament was 38.8 N. Conclusion: The SAAOL was a constant structure of the anterior atlanto-occipital joint. This ligament seems to be a secondary stabilizer of the CCJ by limiting the extension of CCJ. Knowledge of this ligament may help in further understanding of craniocervical stability.

Purpose: Morphometric evaluation of the craniocervical region using magnetic resonance imaging method in humans and determination of the reference values that could be used in various clinics were the aims of this study. Materials and Methods: In our study, 306 (95 males and 211 females) individuals who met the necessary criteria for anatomical structure were included and taken measurements afterward. Sagittal T1- and T2-weighted images were determined as a section thickness of 3 mm, an interval of 10 mm, a matrix of 352 × 224, a field of view of 170–240 mm, and a number of excitations of 4. Measurements of anatomical structures in the craniocervical region were taken via these images. Results: Statistically significant differences were found among the findings of male and female individuals such as height of dens axis, anteroposterior distance of the dens axis (APDDA), anterosuperior distance of the dens axis (ASDDA), sagittal diameter of the foramen magnum (SDFM), total cervical vertebra length (TCVL), distance of spatium retropharyngeum, Pavlov ratio, and the ratio between sagittal diameter of canalis vertebralis (SDCV) to the APDDA. Dens axis height showed a positive correlation with ASDDA and TCVL, and a negative correlation was found between the APDDA and the spatium retropharyngeum. Conclusion: Age- and sex-related changes in the measurements of anatomical regions reveal that an increase and a decrease in the various parameters reveal that these are the normal changes presumably determined by the functional and physical demands varying on the columna vertebralis.

Context: Multiple angles of the craniocervical junction (CCJ) are associated with pathological conditions and surgical outcomes, including the clivo-axial angle (CXA), clival slope (CS), and sagittal axis (XS). However, there are varying normative ranges reported and a paucity of data analyzing the effects of imaging modality, age, and gender on these angles. Setting and Design: A retrospective review of computed tomographic (CT) and magnetic resonance imaging (MRI) scans in fifty adults without CCJ pathology from 2014 to 2019. Methods: Age, gender, indication, and hours between scans were recorded. Two-blinded observers measured all angles. Analysis between angles from the same patient was performed using the Wilcoxon signed-rank test. Multivariable linear regression was used to test for associations between average angles and age or gender. Results: Average age and time between scans were 41.3 and 14.3 h, respectively, with 94% performed due to trauma. On CT, average CXA, CS, and XS were 162.1°, 118.4°, and 81.3°, respectively. On MRI, they were 159.8°, 117.2°, 85.3°, respectively. There were statistically significant differences between CXA and XS (P < 0.01) based on imaging modality. On CT, there was a significant increase in XS by 1.93°° and decrease in CS by 1.88°° and on MRI, there was a significant increase in CXA by 1.93°° and decrease in CS by 2.75°° corresponding with a 10-year advancement of age. Gender did not have an effect. Conclusion: There are significant differences in angular measurements of the CCJ between CT and MRI from the same patient, as well as changes in normative values based on age.

Background In the absence of frank craniocervical dissociation, there is a lack of consensus regarding what patterns of craniocervical junction ligamentous injuries require occipital-cervical fusion. This study was undertaken to examine the integrity of the craniocervical junction ligaments and analyze clinical outcomes in patients who underwent occipital-cervical fusion for craniocervical junction injury. Methods Adult patients requiring occipital-cervical fusion were identified retrospectively utilizing keyword searches in cervical computed tomography and magnetic resonance imaging reports between 2012 and 2020 using Nuance mPower software (Nuance, Burlington, MA). The cervical magnetic resonance imaging examinations for these patients were reviewed for craniocervical ligamentous injury by two neuroradiologists. Descriptions of craniocervical junction injuries, demographic information, clinical history, surgical management, and global outcomes were recorded. Results Nine adult patients were identified with an acute, post-traumatic craniocervical junction injury requiring occipital-cervical fusion. All nine patients demonstrated a ligamentous tear in at least one of the four major craniocervical junction ligaments - the occipital condylar-C1 capsular ligaments, alar ligaments, tectorial membrane, and posterior atlantooccipital membrane. The tectorial membrane was the most commonly torn ligament followed by the alar ligament(s), posterior atlantooccipital membrane, and capsular ligament(s). There was wide variability in the number of major craniocervical junction ligaments torn, ranging from one ligament to all four ligaments. Four patients suffered persistent neurologic deficits following surgery. Conclusion Craniocervical injury is best evaluated by cervical magnetic resonance imaging. In the absence of overt craniocervical dissociation, we propose that an injury of the tectorial membrane in the adult population may indicate patients with significant craniocervical instability, possibly necessitating occipital-cervical fusion.

Background Several central nervous system diseases are associated with disturbed cerebrospinal fluid (CSF) flow patterns and have typically been characterized in vivo by phase-contrast magnetic resonance imaging (MRI). This technique is, however, limited by its applicability in space and time. Phase-contrast MRI has yet to be compared directly with CSF tracer enhanced imaging, which can be considered gold standard for assessing long-term CSF flow dynamics within the intracranial compartment. Methods Here, we studied patients with various CSF disorders and compared MRI biomarkers of CSF space anatomy and phase-contrast MRI at level of the aqueduct and cranio-cervical junction with dynamic intrathecal contrast-enhanced MRI using the contrast agent gadobutrol as CSF tracer. Tracer enrichment of cerebral ventricles was graded 0–4 by visual assessment. An intracranial pressure (ICP) score was used as surrogate marker of intracranial compliance. Results The study included 94 patients and disclosed marked variation of CSF flow measures across disease categories. The grade of supra-aqueductal reflux of tracer varied, with strong reflux (grades 3–4) in half of patients. Ventricular tracer reflux correlated with stroke volume and aqueductal CSF pressure gradient. CSF flow in the cerebral aqueduct was retrograde (from 4th to 3rd ventricle) in one third of patients, with estimated CSF net flow volume about 1.0 L/24 h. In the cranio-cervical junction, net flow was cranially directed in 78% patients, with estimated CSF net flow volume about 4.7 L/24 h. Conclusions The present observations provide in vivo quantitative evidence for substantial variation in direction and magnitude of CSF flow, with re-direction of aqueductal flow in communicating hydrocephalus, and significant extra-cranial CSF production. The grading of ventricular reflux of tracer shows promise as a clinical useful method to assess CSF flow pattern disturbances in patients. Graphic abstract

Background The posterior atlantooccipital membrane complex consists of the posterior atlantooccipital membrane and posterior atlantoaxial membrane. Posttraumatic, posterior atlantooccipital membrane complex injuries may have varied appearances on cervical magnetic resonance imaging. The purpose of this study was to identify the different types of posterior atlantooccipital membrane complex injuries that occur in trauma patients. Methods Patients who suffered a posterior atlantooccipital membrane complex injury were identified retrospectively using key word searches of cervical magnetic resonance imaging reports between 2013 and 2020 using Nuance mPower software. All relevant imaging studies were reviewed by 2 neuroradiologists. A description of the location and type of posterior atlantooccipital membrane complex injury was recorded, along with additional osteoligamentous trauma of the craniocervical junction and relevant clinical history. Results Forty-one patients were identified with acute posterior atlantooccipital membrane complex injury. Four distinct patterns of posterior atlantooccipital membrane complex injury were observed. Conclusions A grading system for posterior atlantooccipital membrane complex injuries is proposed on the basis of these data: grade 1—edema confined to the posterior atlantooccipital and atlantoaxial membrane; grade 2—edema confined to the posterior atlantooccipital and atlantoaxial membrane and ligamentum nuchae; grade 3—stripping injury of the posterior atlantooccipital membrane with C1-C2 dorsal epidural hematoma; and grade 4—frank disruption of the posterior atlantooccipital membrane at C1 with edema in the remaining posterior atlantooccipital membrane complex.

Objectives We present a challenging case of a 61-year-old male patient with a double meningioma. The first one was located on the right side of foramen magnum and the second one was located on left anterolateral side of C1–C2. Background Patient referred at our institution for a progressive spastic paraparesis from approximately 1 year with a recent onset of numbness in right hand. Neuroradiological imaging showed an extra-axial enhancing tumor with a dural tail on the right border of foramen magnum and another contralateral extra-axial enhancing lesion at C1–C2 level (Fig. 1). Results We have chosen a park bench position. Neurophysiological monitoring was used during both positioning and surgery. A linear skin incision in the occipital region extended to C7 was performed and a suboccipital craniotomy with the laminectomy of C1–C3 was performed (Fig. 2). Videofluroangiography was performed to the best visualization of the vertebral artery position during microsurgical dissection and exposure of craniovertebral junction region. An Y-shape dural opening was executed and two meningiomas was resected with the classical four D steps (devascularize, detach, debulking, and dissect). All anatomical structures were respected and there were no changes at neuromonitoring. Patient was discharged after 10 days in good neurological condition. Conclusion a single approach for multiple meningiomas of the craniovertebral junction and upper cervical spine region is feasible and effective. Videofluoroangiography as a way to achieve better visualization and control of the vertebral artery, and neurophysiological monitoring are crucial tools to reduce the morbidity of this surgical challenge.The link to the video can be found at: https://youtu.be/4w9HCfQZkgg.

Aim To assess the clinical picture underlying apparent life-threatening events (ALTEs) occurring in infants with achondroplasia and provide guidance for evaluation after an event. Methods A population of 477 individuals with achondroplasia was retrospectively reviewed, and information regarding possible ALTEs was recorded in a REDCap database. Results ALTEs occurred in the first year of life in 18 of 477 individuals (3.8%). Most (14/18, 78%) occurred in the first 6 months of life and presented as episodes of apnoea and/or seizures. Of affected infants, 8/18 (44%) had more than one episode. Many of the initial ALTEs arose while infants were in car seats (11/18, 61%). Assessment following ALTEs most often demonstrated either craniocervical junction concerns and/or seizures, with 12/18 (67%) patients undergoing cervicomedullary decompression and 5/18 (28%) starting on anti-epileptic medications after the event. Conclusion Although this study is limited in size and was retrospective, it shows that infants with achondroplasia appear to be at high risk for ALTEs. Evaluation after an event should include neuroimaging of the foramen magnum, inpatient hospital observation including respiratory monitoring and electroencephalography, and a car seat challenge.

The Endoscopic Endonasal Far-Medial approach represents the coronal expansion of the conventional endoscopic endonasal approach to the lower third of the clivus, which allows access to the condylar region and adjacent structures such as the jugular foramen, jugular tubercle, and the craniocervical junction.

The craniocervical junction (CCJ) forms a transition between the brain and cervical spine and comprises the foramen magnum, atlas (C1), axis (C2), ligaments, and musculature associated with the C1-C2 vertebrae. The CCJ is comprised of the inferior surface of the skull, the atlas, and axis, as well as muscles and connective tissue that attach the skull to the cervical spine. The major vascular and nervous structures surrounding this junction make it one of the most challenging, not only in terms of approach but also in terms of stabilization. Multiple approaches to the CCJ have been described, including anterior, ventral, posterior, and lateral. The choice of approach is dictated by the location and nature of the tumor compression, and it is important to understand the growing pattern in tumoral cases. In this chapter, we will review some of the most common approaches to the CCJ and the indications for each of these.

Chiari malformations encompass various radiological and clinical entities, sharing the herniation of the rhombencephalic structures through the foramen magnum as a common characteristic. They can be symptomatic or asymptomatic. The therapeutic strategies for these malformations differ on the basis of the diverse pathophysiologic processes that cause them. As Chiari malformations are caused by various pathophysiologic processes, they must be recognized promptly to select the best treatment for each single case.

BackgroundAchondroplasia is the most common dwarfing disorder. It can result in a variety of sequelae, including neurologic complications, among which high cervical myelopathy is one of particular concern. However, some individuals with achondroplasia appear to have persistent signs by physical examination that, while they might suggest the presence of high cervical myelopathy, remain isolated, non-progressive and apparently benign. To document and quantify these apparently benign craniocervical signs (ABCS) a cohort of 477 individuals with achondroplasia was retrospectively analyzed and information regarding persistent neurologic features suggestive of high cervical myelopathy was recorded in a REDCap database.ResultsWithin this cohort, 151 individuals (31.7%) had neurologic examinations that were in some manner concerning. Of these, 46 (30.5% of the subpopulation) required cervicomedullary decompressive surgery. The remaining 105 had concerning signs by examination but no apparent evidence for clinically significant cervical myelopathy. Of those 105 individuals, 88 (83.8%; 18.4% of the entire population) remained neurologically intact throughout their follow-up, and without clinical sequelae.ConclusionsIt appears that many individuals with achondroplasia, if carefully examined, may demonstrate isolated, initially concerning signs suggestive of cervical myelopathy, but in the vast majority these are benign and do not indicate need for aggressive neurosurgical intervention. Further investigations may help to identify ways to differentiate these benign features from the less common but more problematic true myelopathic ones. We postulate that the “neurologic leftovers” may arise from temporally remote, subtle damage to the spinal cord at the craniocervical junction, which damage otherwise does not reach clinical relevance.

Background Non-missile penetrating injuries to the craniocervical junction caused by a glass fragment are rare, and a standard management strategy has not been established. Case description A 75-year-old Japanese man was brought into our emergency department after receiving a left retroauricular stab wound by broken glass fragments. After spinal immobilization, a computed tomographic (CT) scan revealed glass fragments penetrating at the right craniocervical junction to the inter-atlanto-occipital subarachnoid space. CT angiography showed that both vertebral arteries (VAs) were not injured. Magnetic resonance imaging demonstrated that the glass fragments did not penetrate the cervical cord or medulla oblongata (MO). These glass fragments were removed via a midline incision from the external occipital protuberance to the C7 and with laminectomy without suboccipital craniectomy. Five of the glass fragments were found and removed in total. The dural defect was patched with a free fascia autograft. His postoperative course was uneventful. Postoperative CT angiography showed that both the vertebral arteries were intact as well as the complete removal of the glass fragments. Conclusions CT graphical diagnosis is useful for the management of penetrating craniocervical junction trauma, and it should be considered in the evaluation of patients who have suffered craniocervical penetrating injury even in the absence of major wounds or bleeding. Spinal immobilization of patients with craniocervical penetrating injuries is crucial to avoid not only secondary neurological damage but also secondary critical vascular damage. Incomplete or inadequate assessment of craniocervical stab wounds results in unexpected hazards that are preventable.

Objective: Atlanto-occipital dislocation is usually considered to be a fatal injury or one that leaves the victim with serious neurological deficits. The aim of this study is to illustrate a novel positive prognostic factor for atlanto-occipital dislocation, based on cervical MRI studies of patients who suffered this injury.Methods: Over the course of the past year, the authors have treated three consecutive patients with atlanto-occipital dislocation who attained an excellent clinical outcome. We retrospectively evaluated clinical, surgical and radiographic parameters in search of a common denominator to explain the excellent outcome of these patients.Results: All patients presented with severe polytrauma that required urgent surgical intervention including two laparotomies and a thoracotomy. The patients were subsequently treated with an occipitocervical fusion. No patient developed neurological deficits on long-term follow-up. The cervical MRI studies of all patients were notable for a having a preserved tectorial membrane, while other primary stabilizers of the craniocervical junction such as the apical, alar and cruciate ligaments were shown to be severely disrupted. We consider this anatomical distinction to account for their benign clinical course.Conclusion: A preserved tectorial membrane appears to be an important favorable prognostic factor in atlanto-occipital dislocation and may serve to mitigate neurological outcome in such injuries. To determine the integrity of the ligament and consequently affect clinical management, expeditious MRI of the cranio-cervical junction should be considered routinely in such injuries in addition to cervical CT scans.

The development of the craniocervical junction is a complex sequence that requires perfect arrangement between cranial and cervical components. The neural crest cells of the upper somites and the notochord are both important in the development of this region. Of particular significance is the proatlas. Recent molecular studies have increased our knowledge of the processes involved in the formation of the base of the skull and upper cervical spine. The orchestration of the developing rhombencephalon and craniocervical junction is critical in the proper adult neuro-osseous relationships. Derailment of these processes may result in hindbrain herniation.

Made available in DSpace on 2022-04-28T19:47:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 A 5-month-old male Rottweiler dog presented with an acute upper motor neuron tetraparesis. A computed tomography study of the cervical spine revealed amorphous mineralization of the soft tissues dorsal to the articular surface of the occipital bone and atlas. The calcification extended into the vertebral canal, causing significant dorsal compression of the spinal cord. Suboccipital craniectomy and partial dorsal atlas laminectomy were performed to remove the extradural calcification. Histopathology was compatible with tumoral calcinosis. Significant clinical improvement was noted in the immediate postoperative period, and there was complete recovery with no recurrence at the last clinical follow-up 15 months postoperatively. Suboccipital craniectomy and partial dorsal atlas laminectomy allowed successful surgical resection of a dorsal craniooccipital tumoral calcinosis in this dog. The decompression resulted in resolution of clinical signs and recurrence is unlikely since there is no underlying disease. Department of Veterinary Clinics and Surgery Sao Paulo State University (Unesp) Department of Veterinary Clinics and Surgery Sao Paulo State University (Unesp)

Foramen magnum (FM) tumors represent one of the most complex cases for the neurosurgeon, due to their location in a very anatomically complex region surrounded by the brainstem and the lower cranial nerves, by bony elements of the craniocervical junction, and by the vertebrobasilar vessels. Currently, the open approach of choice is a lateral extension of the posterior midline approach including far lateral, and extreme lateral routes. However, the transoraltranspharyngeal approach remains the treatment of choice in cases of diseases affecting the craniocervical junction. For very selective cases, the endoscopic endonasal route to this region is another option. We present a case of a ventral FM meningioma treated exclusively with the endoscopic endonasal approach.

Objectives: Atlanto-occipital assimilation (AOA) is one of the most common skeletal anomalies of the craniovertebral junction (CVJ). Because its clinical symptomatology is non-specific and it has several variations, many cases go unnoticed which may lead to additional and unnecessary radiological examinations. In this study, we aimed to present CVJ abnormalities with MRI to improve diagnostic accuracy of AOA. Methods: Cervical MRIs of the patients registered in PACS between January 2008 and October 2011 were scanned and AOA was detected in 40 cases. Sagittal FSE T1 and T2-weighted cervical MRIs and axial T2*-GRE sequence images were re-evaluated for AOA typing, anterior atlantodental interval (AADI), posterior atlantodental interval (PADI) measurements, spine fusion anomalies, basilar invagination, tonsillar herniation, myelomalacia, suboccipital muscles and vertebral arteries (VAs). Results: CVJ abnormalities were present in all cases and the most frequent association was observed in suboccipital muscles (100%) and VAs (95%). 60% of the cases had decreased PADI, 32% C2–3 vertebrae fusion, 25% increased AADI, 22.5% basilar invagination, 15% myelomalacia and 5% tonsillar herniation. Conclusion: Suboccipital muscle abnormality was found in all AOA cases whatever the severity and type of the bony fusion. VA anomaly was observed as the second most common abnormality and accompanied preferably the cases with lateral body involvement. Being aware of additional CVJ abnormalities in MRI examinations may reduce unnecessary radiological examinations by increasing the AOA diagnosis rate.

Although the embryology of the posterior cranial fossa can have life altering effects on a patient, a comprehensive review on this topic is difficult to find in the peer-reviewed medical literature. Therefore, this review article, using standard search engines, seemed timely. The embryology of the posterior cranial fossa is complex and relies on a unique timing of various neurovascular and bony elements. Derailment of these developmental processes can lead to a wide range of malformations such as the Chiari malformations. Therefore, a good working knowledge of this embryology as outlined in this review of its bony architecture is important for those treating patients with involvement of this region of the cranium. Clin. Anat. 31:466-487, 2018. © 2018 Wiley Periodicals, Inc.

Although pathology of the hindbrain and its derivatives can have life altering effects on a patient, a comprehensive review on its embryology is difficult to find in the peer-reviewed medical literature. Therefore, this review article, using standard search engines, seemed timely. The embryology of the hindbrain is complex and relies on a unique timing of various neurovascular and bony elements. Derailment of these developmental processes can lead to a wide range of malformations such as the Chiari malformations. Therefore, a good working knowledge of this embryology as outlined in this review of the hindbrain is important for those treating patients with involvement of this region of the central nervous system. Clin. Anat. 31:488-500, 2018. © 2018 Wiley Periodicals, Inc.

Objective This study was aimed to achieve gross-total removal of a chordoma of the craniocervical junction via an endonasal approach ( Fig. 1 ). Fig. 1 Pre- and postoperative images of the craniocervical junction chordoma. ( A ) It shows a preoperative sagittal T2-weighted MRI image. ( B ) It shows a preoperative axial T2-weighted MRI image. Note that a T2-hyperintense lesion is located in the lower clivus and the odontoid. ( C ) It shows the postoperative sagittal T1-weighted gadolinium enhanced MRI image. ( D ) shows a postoperative axial T2-weighted MRI image. These images show the fat graft used for closure, but no evident tumor remnant. MRI, magnetic resonance imaging Design The present study is a case report. Setting The study was conducted at neurosurgical clinic of university hospital. Participant A 40-year-old male, with normal neurologic exam and no prior medical history, presented with a 2-year history of cervicalgia. On preoperative imaging, a midline lesion, with image characteristics of chordoma, was seen in the lower clivus and odontoid. It had limited lateral extension. Main Outcome Measures This study measures postoperative neurological deficits and postoperative tumor volume on magnetic resonance imaging (MRI). Results A binostril approach to the upper nasopharynx was performed using endoscope at 30- and 45-degree angles. Subsequently, a heart-shaped mucosal flap was made and the clivus was drilled to expose the lesion ( Fig. 2 ). After initial debulking, the ring of C1 was slightly drilled to reach the tumor in and around the odontoid. Postoperative MRI showed that a gross-total resection was achieved. The patient had no neurologic deficits postoperatively. Pathologic examination revealed a chordoma of the classical type. Fig. 2 Illustration of the endoscopic endonasal surgical technique. ( A ) It shows the surgical route (blue arrow), and location of the heart-shaped mucosal flap that was made in the upper nasopharynx (blue crescent). This figure highlights that angled endoscopes are needed to visualize the relevant operative field (yellow translucent triangle). ( B ) shows the axial view, ( C ) shows an intraoperative endoscopic view of the incision performed to achieve a heart-shaped mucosal flap, as was utilized during this case, and ( D ) shows the coronal view. ( B and D ) They show the results of postoperative image analysis, during which we segmented the drill cavity (in blue) and projected it on the preoperative CT scan of the patient. Note that besides the inferior clivus, the superior part of the ring of C1 was also drilled slightly to reach the tumor in the odontoid. CT, computed tomography. Conclusion An endoscopic endonasal approach, utilizing the heart-shaped flap and angled endoscopes and instruments, can be considered for resection of select cases of craniocervical junction chordoma with limited lateral expansion. The link to the video can be found at: https://youtu.be/rwVoZJRBIEo .

The extreme lateral infrajugular transcondylar-transtubercular exposure (ELITE) is a surgical approach developed in the late 1980s by Prof. T. Fukushima and represents the dorsolateral inferior skull base procedure of choice to approach lesion located ventrolaterally at the level of the craniocervical junction (CCJ). This approach consist in a suboccipital craniotomy/craniectomy with partial condylectomy and jugular tubercule drilling that can be extended providing for subtotal condylectomy and vertebral artery transposition. The “limited” variation of the ELITE approach consist in a lateral suboccipital craniectomy opening the foramen magnum and removal of at least half of the posterior arch of the atlas without condyle drilling. This surgical technique was recently demonstrated to be particularly suitable for the surgical management of spinal tumor located ventrolaterally in the upper cervical spine. This operative video illustrates step-by-step the surgical technique adopted for the microsurgical resection of a C1-C2 intradural schwannoma located antero-laterally ( Video 1 ). ELITE approach offers a wide and adequate exposure and access to the CCJ, allowing direct visualization and access to the tumor with minimal neural manipulations, early detection of the vertebral artery and, for tumor located at C1-C2 level, without drilling the occipital condyle. In our experience, ELITE procedure is the preferred surgical approach for resection of tumors located ventrally or ventrolaterally to the first 2 cervical levels.

BACKGROUND: Frequently, treatment decisions for craniocervical injuries and instability are based on imaging findings, but in vivo ligament kinematics were poorly understood. This study was to determine in vivo deformation patterns of primary ligaments in the craniocervical junction (i.e., C0-2), including the cruciform ligament, alar ligaments, and accessory ligaments, during dynamic head axial rotation. METHODS: The skulls and cervical spines of eight asymptomatic female subjects were dynamically imaged using a biplane fluoroscopic imaging system, when they performed left and right head axial rotations. Using a 3D-to-2D registration technique, the in vivo positions and orientations of cervical segments were determined. An optimization algorithm was implemented to determine ligament wrapping paths, and the resulting ligament deformations were represented by percent elongations. Using paired t-tests, ligament deformations in the end-range position were compared to those in the neutral position. FINDINGS: No significant differences were observed in segmental motions during left and right head rotations (p > 0.05). In general, slight deformations occurred in each component of the cruciform ligament. For the alar ligaments, the ipsilateral ligament was lengthened from −0.7 ± 13.8% to 16.6 ± 15.7% (p < 0.001*). For the accessory ligaments, the contralateral ligament was lengthened from −2.9 ± 7.5% to 10.1 ± 6.2% (p < 0.001*). INTERPRETATION: This study reveals that there are distinct deformation patterns in craniocervical junction ligaments during dynamic axial head rotation. These ligament deformation data can enhance our understanding of the synergic function of craniocervical junction ligaments, and guide the treatment of craniocervical instability.

The atlanto-occipital joint (AOJ) is an important transitional region, which supports and stabilizes the cranium to the spine with its surrounding ligamentous structures. An injury to this joint is often accompanied by brain injury and may be fatal. A good understanding of the anatomy of this joint is required to timely diagnose an AOJ instability and intervene via the means of an immediate fixation. We discuss the normal anatomy of and anatomical variations within the occipito-atlantoaxial complex, the classification systems to describe its disruption, and its clinical significance.

Study DesignA retrospective computed tomography (CT)-based morphometric study of 82 occipital condyles in the Indian population, focusing on critical morphometric dimensions with relation to placing condylar screws.PurposeThis study focused on determining the feasibility of placing occipital condylar screws in an Indian population using CT anatomical morphometric data.Overview of LiteratureThe occipital condylar screw is a novel technique being explored as one of the options in occipitocervical stabilization. Sex and ethnic variations in anatomical structures may restrict the feasibility of this technique in some populations. To the best of our knowledge, there are no CT-based data on an Indian population that assess the feasibility of occipital condylar screws.MethodsWe measured the dimensions of 82 occipital condyles in 41 adults on coronal, sagittal, and axial reconstructed CT images. The differences were noted between the right and left sides and also between males and females. Statistical analysis was performed using the t-test, with a p-value of ResultsMean sagittal length and height were 17.2±1.7 mm and 9.1±1.5 mm, respectively. Mean condylar angle/screw angle was 38.0°±5.5° from midline, with mean condylar length and width of 19.6±2.6 mm and 9.5±1.0 mm, respectively. Average coronal height on the anterior and posterior hypoglossal canal was 10.8±1.4 mm and 9.0±1.4 mm, respectively. The values in females were significantly lower than those in males, except for screw angle and condylar width. Based on Lin et al.'s proposed criteria, eight of 82 condyles were not suitable for condylar screws.ConclusionsPreliminary CT morphometry data of the occipital condyle shows that condylar screws are anatomically feasible in a large portion of the Indian population. However, because a small number of population may not be suitable for this technique, meticulous study of preoperative anatomy using detailed CT data is advised.

In 1922, Paul Hecker, a French physician and Head of Anatomy at the Medical College of Strasbourg, published a sentinel thesis on the ligaments of the craniocervical junction based on a study of comparative anatomy. Unfortunately, this dissertation has been lost to history and until now, was unavailable in the English language. Herein, we present a translation of Hecker's work with an update in its nomenclature, which with modern imaging capabilities of the craniocervical junction is germane and timely. Clin. Anat. 30:322–329, 2017. © 2017 Wiley Periodicals, Inc.

Background: Adult craniocervical junction malformations have been described as Chiari malformation (CM) and Basilar invagination (BI). Recently, angular craniometric studies have identified differences among subtypes of malformations and reveled new relationships between skull and spine. Objective: The scope of this study is to summarize the knowledge related to craniometric relationship in pathophysiology of these diseases. Results: In CM, angular craniometric measures are not different from normal controls. In BI type I and II there is an increased craniocervical Kyphosis associated to cervical spine lordosis. Chamberlain’s line violation evaluation reveals that there is a downward angulation of the skull towards the upper cervical spine in BI. Conclusion: BI should be considered a craniometrical kyphosis rather than a prolapse of the cervical spine to the skull base.