Imaging of Atlanto-Occipital and Atlantoaxial Traumatic Injuries: What the Radiologist Needs to Know

Grisel's Syndrome After COVID-19 in a Pediatric Patient: A Case Report

An eight-year-old female presenting with posterior neck pain and torticollis who had been diagnosed with coronavirus disease 2019 (COVID-19) three weeks earlier was radiographed and diagnosed with atlantoaxial rotatory fixation (AARF). Following treatment with non-steroidal anti-inflammatory drugs (NSAIDs), the posterior neck pain improved, and the torticollis was cured. Symptoms returned after two weeks, and computed tomography showed a 3.94 mm atlantodental interval and axis rotation. The patient was diagnosed with AARF relapse; symptoms resolved spontaneously prior to subsequent examination, and no further relapses were observed. This case highlights the need for clinicians to be aware that AARF may develop after COVID-19. Treatment options should be carefully considered.

Imaging Assessment of Nontraumatic Pathologic Conditions at the Craniovertebral Junction: A Comprehensive Review

Nontraumatic pathologic conditions of the craniovertebral junction encompass a range of conditions affecting the complex anatomy of this region without direct physical injury. These conditions include congenital syndromes that predispose individuals to ligamentous laxity, potentially leading to instability. Additionally, rare but noteworthy cases such as Grisel syndrome, a cause of pediatric torticollis, may arise without a traumatic trigger. Inflammatory diseases, including rheumatoid arthritis, ankylosing spondylitis, and crystal deposition, can lead to cervical instability and spinal cord compression. Infections at the upper cervical spine are dominated by tuberculosis, typically transmitted through hematologic or lymphatic routes with characteristic imaging findings. On the other hand, purulent bacterial infections in this area are rare. Furthermore, although tumors involving the structures of the craniovertebral junction are infrequent, they can lead to significant complications, albeit less frequently through cord compression and more commonly via pathologic fractures or subluxation. The craniocervical junction is a complex anatomic region comprising ligaments, bones, joints, and muscles that support the head's weight and enable its wide range of motion. Accurate recognition and understanding of the complex anatomy and the various nontraumatic pathologic conditions at the craniovertebral junction are pivotal for initiating timely and appropriate treatment strategies. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Demonstration of transverse ligament on 3D SPACE MRI in whiplash-associated disorder and nontraumatic conditions

PURPOSE

This study aims to delineate the three-dimensional (3D) SPACE MRI findings of the transverse ligament (TL) in whiplash-associated disorder (WAD) patients, and to compare them with those from a nontraumatic group.

METHODS

A retrospective analysis was performed on cervical spine MRI scans obtained from 46 patients with WAD and 62 nontraumatic individuals. Clinical features, including the WAD grade and stage, were recorded. The TL's morphological grade and the symmetricity of the lateral atlantodental interval was assessed using axial 3D T2-SPACE images. The morphological grading was evaluated using a four-point scale: 0 = homogeneously low signal intensity with normal thickness, 1 = high signal intensity with normal thickness, 2 = reduced thickness, 3 = full-thickness rupture or indistinguishable from surrounding structures. Additionally, the number of cervical levels exhibiting degeneration was documented.

RESULTS

When comparing the WAD and nontraumatic groups, a significant difference was observed in the proportion of high-grade TL changes (grade 2 or 3) and the number of degenerated cervical levels. Logistic regression analysis revealed that high-grade TL changes and a lower number of degenerative levels independently predicted the presence of WAD. Within the WAD group, the subset of patients with high-grade TL changes demonstrated a significantly higher mean age than the low-grade group (grade 0 or 1).

CONCLUSION

High-grade morphological changes in the TL can be detected in patients with WAD through the use of 3D SPACE sequences. Clinical relevance statement 3D SPACE MRI could serve as an instrumental tool in the assessment of TL among patients with WAD. Integrating MRI findings with patient history and symptomology could facilitate the identification of potential ligament damage, and may help treatment and follow-up planning.

Craniocervical instability in patients with Ehlers-Danlos syndromes: outcomes analysis following occipito-cervical fusion

Craniocervical instability (CCI) is increasingly recognized in hereditary disorders of connective tissue and in some patients following suboccipital decompression for Chiari malformation (CMI) or low-lying cerebellar tonsils (LLCT). CCI is characterized by severe headache and neck pain, cervical medullary syndrome, lower cranial nerve deficits, myelopathy, and radiological metrics, for which occipital cervical fusion (OCF) has been advocated. We conducted a retrospective analysis of patients with CCI and Ehlers-Danlos syndrome (EDS) to determine whether the surgical outcomes supported the criteria by which patients were selected for OCF. Fifty-three consecutive subjects diagnosed with EDS, who presented with severe head and neck pain, lower cranial nerve deficits, cervical medullary syndrome, myelopathy, and radiologic findings of CCI, underwent open reduction, stabilization, and OCF. Thirty-two of these patients underwent suboccipital decompression for obstruction of cerebral spinal fluid flow. Questionnaire data and clinical findings were abstracted by a research nurse. Follow-up questionnaires were administered at 5-28 months (mean 15.1). The study group demonstrated significant improvement in headache and neck pain (p < 0.001), decreased use of pain medication (p < 0.0001), and improved Karnofsky Performance Status score (p < 0.001). Statistically significant improvement was also demonstrated for nausea, syncope (p < 0.001), speech difficulties, concentration, vertigo, dizziness, numbness, arm weakness, and fatigue (p = 0.001). The mental fatigue score and orthostatic grading score were improved (p < 0.01). There was no difference in pain improvement between patients with CMI/LLCT and those without. This outcomes analysis of patients with disabling CCI in the setting of EDS demonstrated significant benefits of OCF. The results support the reasonableness of the selection criteria for OCF. We advocate for a multi-center, prospective clinical trial of OCF in this population.

Imaging in Whiplash-Associated Disorders

"Whiplash," a term describing the severe acceleration and deceleration forces applied to the head, craniocervical junction (CCJ), and cervical spine during trauma, is one of the most frequent mechanisms of injury to the CCJ. The CCJ is a complex region at the transition of the cranium and the cervical spine, essential for maintaining craniocervical stability. In whiplash injuries, the CCJ may be compromised due to underlying ligamentous or, less frequently, osseous, intravertebral disk and/or muscular lesions. Imaging is crucial in detecting acute lesions but may also play a role in the follow-up of chronic pathology because soft tissue lesions and progressive disk pathology could contribute to a whiplash-associated disorder.

Relationship of cervical soft tissue injury and surgical predication following pediatric cervical spinal trauma and its sequelae on long-term neurologic outcome

Within the sample of 181 patients with cervical CT, CT identified unstable injury with a sensitivity of 100% and specificity of 95%. CT identified operable injury at the CCJ with 86% sensitivity and 91% specificity. CT was considered the gold standard for identification of fractures. Together, the presence of CT imaging suggestive of unstable injury or persistent neurologic complaint had a 100% sensitivity and 81% specificity. Finally, across all patients MRI had 100% sensitivity and 89% specificity for detection of unstable injury requiring surgery.

Pediatric Spinal Cord Injury: A Review

A spinal cord injury (SCI) can be a devastating condition in children, with profound implications for their overall health and quality of life. In this review, we aim to provide a concise overview of the key aspects associated with SCIs in the pediatric population. Firstly, we discuss the etiology and epidemiology of SCIs in children, highlighting the diverse range of causes. We explore the unique anatomical and physiological characteristics of the developing spinal cord that contribute to the specific challenges faced by pediatric patients. Next, we delve into the clinical presentation and diagnostic methods, emphasizing the importance of prompt and accurate diagnosis to facilitate appropriate interventions. Furthermore, we approach the multidisciplinary management of pediatric SCIs, encompassing acute medical care, surgical interventions, and ongoing supportive therapies. Finally, we explore emerging research as well as innovative therapies in the field, and we emphasize the need for continued advancements in understanding and treating SCIs in children to improve their functional independence and overall quality of life.

Emergency MRI in Spine Trauma of Children and Adolescents-A Pictorial Review

Severe spinal trauma is uncommon in the pediatric population, but due to the potentially devastating consequences of missed injury, it poses a diagnostic challenge in emergency departments. Diagnostic imaging is often needed to exclude or confirm the injury and to assess its extent. Magnetic resonance imaging (MRI) offers an excellent view of both bony and soft tissue structures and their traumatic findings without exposing children to ionizing radiation. Our pictorial review aims to demonstrate the typical traumatic findings, physiological phenomena, and potential pitfalls of emergency MRI in the trauma of the growing spine.

Risk factors for atlantoaxial dislocation in rheumatoid arthritis: A comparative study

BACKGROUND

The objective of the study was to assess clinical and imaging features of rheumatoid arthritis associated with atlantoaxial dislocation (RA-AAD) in comparison to RA without AAD (RA-C) and to identify the associated factors to AAD.

METHODS

This was a retrospective comparative study including RA patients over 18 years old. The control group of RA-C was matched according to age (±2 years), gender, and RA duration (±2 years). General data, RA characteristics, AAD features, and treatment modalities were recorded. Statistical analysis was performed to determine the predictive factors of AAD.

RESULTS

A total of 120 patients were included (78 RA-AAD and 42 RA-C); sex-ratio was 0.15. Mean age was 58.55 ± 9.14 years (RA-AAD) versus 60.43 ± 10.78 years (RA-C), (p = 0.31). Regarding RA features, RA-AAD patients have significantly a higher rheumatoid factor (RF) rate (p = 0.002), extra-articular manifestations (p = 0.009) especially osteoporosis (p < 10^-3 ), eye involvement (p = 0.02), coxitis (p < 0.0001), Disease Activity Score (DAS28) (p < 10^-3 ), and global health status scale (HAQ) (p = 0.003). X-ray analysis showed pathologic PADI (<14 mm) in 51.6% of cases. The AADI was pathological (>3 mm) in 100% of patients with the following distribution: 67.9% between (3-6 mm) and 23.3% between (6-9 mm). Atlantoaxial dislocation (AAD) was presumed anterior (85.4%), lateral (7.3%) and rotatory (7.3%). The abnormalities observed on magnetic resonance imaging (MRI) were: C1-C2 synovitis (61%), confirmed AAD (34.1%) and basilar impression (4.9%). AAD diagnosed by cervical MRI was anterior in 89.8% of cases, lateral (5.3%) and with a double ascending and anterior component in 4.9% of cases. An immobilisation with a type C4 cervical collar was indicated for all the patients and five of them had boluses of corticosteroid (methylprednisolone 1 g/day) for three consecutive days. C1-C2 arthrodesis by trans-articular screwing was performed in four patients with neurological signs or pathological measurements on cervical MRI. The outcome was favourable in 100% of cases after surgical treatment with improvement in neck pain and neurological condition within a mean decline of 4 ± 3 years [1-7]. Multivariate analysis identified coxitis, osteoporosis, high baseline DAS28, and a high rate of RF positivity as predictive factors of AAD.

CONCLUSION

Our results confirmed that predictive factors of AAD were related to higher disease activity and structural damage. These modifiable factors may be prevented by tight control, early treatment, and educating RA patients to improve treatment adherence.

Case report: Interdisciplinary treatment of complex C1/C2 fractures in a patient with concomitant three-vessel coronary artery disease requiring bypass surgery

Background

Acute myocardial infarction (MI) frequently leads to consciousness disturbance following hemodynamic collapse. Therefore, MI can occur together with upper cervical spine trauma. Herein, we report the successful treatment of complex C1/C2 fractures in a patient with concomitant three-vessel coronary artery disease (CAD).

Case presentation

A 70-year-old patient presented in our emergency outpatient clinic after a hemodynamic collapse without neurological deficits or heart-related complaints. Computed tomography (CT) scan of the cervical spine revealed a dislocated odontoid fracture Anderson and D'Alonzo type II and an unstable Gehweiler type III injury (Jefferson's fracture). An intradiploic arachnoid cyst in the posterior wall of the posterior fossa was a coincident radiological finding. Furthermore, coronary angiography confirmed three-vessel CAD with high-grade coronary artery stenosis. Indication for upper cervical spine surgery and bypass surgery was given. An interdisciplinary team of neurosurgeons, cardiothoracic surgeons and anesthesiologists evaluated the patient's case to develop the most suitable therapy concept and alternative strategies. Finally, in first step, C1-C2 fusion was performed by Harms technique under general anesthesia with x-ray guidance, spinal neuronavigation, Doppler ultrasound and cardiopulmonary monitoring. Cardiothoracic surgeons were on standby. One month later bypass surgery was performed uneventfully. Follow-up CT scan of cervical spine revealed intraosseous screw positioning and beginning fusion of the fractures. The patient did not develop neurological deficits and recovered completely from both surgeries.

Conclusions

Treating complex C1/C2 fractures with concomitant severe CAD requiring treatment is challenging and carries a high risk of complications. To our knowledge, the literature does not provide any guidelines regarding therapy of this constellation. To receive upper cervical spine stability and to prevent both, spinal cord injury and cardiovascular complications, an individual approach is required. Interdisciplinary cooperation to determine optimal therapeutic algorithms is needed.

Cervical MRI assessment of traumatic anterior atlanto-occipital membrane complex injuries with evaluation of ancillary findings

BACKGROUND AND PURPOSE

The purpose of this study was to identify and classify the different types of anterior atlanto-occipital membrane complex injuries on MRI and evaluate for the presence, size, and location of a prevertebral effusion on the preceding CT exams.

MATERIALS AND METHODS

Patients who suffered an anterior atlanto-occipital membrane complex injury were identified retrospectively utilizing Nuance mPower software. An anatomic-based description of the location of the anterior atlanto-occipital membrane complex injury was recorded along with any additional osteoligamentous trauma of the craniocervical junction. The preceding cervical CT exams for these patients were reviewed for the presence and location of a prevertebral effusion.

RESULTS

Fifty patients were identified with an acute, post-traumatic anterior atlanto-occipital membrane complex injury. Three distinct patterns of anterior atlanto-occipital membrane complex injury were observed. Nineteen patients demonstrated increased STIR signal with disruption of the anterior atlanto-occipital membrane, ten patients demonstrated increased STIR signal with disruption of the anterior atlanto-axial membrane, and twenty-one patients demonstrated increased STIR signal with disruption of both the anterior atlanto-occipital membrane and anterior atlanto-axial membrane. An effusion at the C1-C2 level was present in greater than 90% of patients with anterior atlanto-occipital membrane complex injury.

CONCLUSIONS

The presence of a craniocervical prevertebral effusion on CT in trauma patients may raise suspicion for an injury to the anterior atlanto-occipital membrane complex and potentially trigger additional investigation with cervical MRI.

Craniovertebral Junction Instability after Oncological Resection: A Narrative Review

The craniovertebral junction (CVJ) is a complex transition area between the skull and cervical spine. Pathologies such as chordoma, chondrosarcoma and aneurysmal bone cysts may be encountered in this anatomical area and may predispose individuals to joint instability. An adequate clinical and radiological assessment is mandatory to predict any postoperative instability and the need for fixation. There is no common consensus on the need for, timing and setting of craniovertebral fixation techniques after a craniovertebral oncological surgery. The aim of the present review is to summarize the anatomy, biomechanics and pathology of the craniovertebral junction and to describe the available surgical approaches to and considerations of joint instability after craniovertebral tumor resections. Although a one-size-fits-all approach cannot encompass the extremely challenging pathologies encountered in the CVJ area, including the possible mechanical instability that is a consequence of oncological resections, the optimal surgical strategy (anterior vs posterior vs posterolateral) tailored to the patient's needs can be assessed preoperatively in many instances. Preserving the intrinsic and extrinsic ligaments, principally the transverse ligament, and the bony structures, namely the C1 anterior arch and occipital condyle, ensures spinal stability in most of the cases. Conversely, in situations that require the removal of those structures, or in cases where they are disrupted by the tumor, a thorough clinical and radiological assessment is needed to timely detect any instability and to plan a surgical stabilization procedure. We hope that this review will help shed light on the current evidence and pave the way for future studies on this topic.

Cervical spine trauma

Cervical spine trauma encompasses a wide of injuries, ranging from stable, minor lesions to unstable, complex lesions that can lead to neurologic sequelae or vascular involvement. The Canadian C-Spine Rule and the NEXUS criteria aim to identify individuals with a low risk of cervical spine trauma who can safely forgo imaging tests. In high-risk patients, an imaging test is indicated. In adult patients the imaging test of choice is multidetector computed tomography. Complementary imaging tests such as CT angiography of the supra-aortic vessels and/or magnetic resonance imaging are occasionally necessary. It can be challenging for radiologists to diagnose and classify these lesions, because some of them can be subtle and difficult to detect. This paper aims to describe the most important imaging findings and the most widely used classification systems.

Reference values of four measures of craniocervical stability using upright dynamic magnetic resonance imaging

PURPOSE

To establish reference ranges for four most commonly used diagnostic measures of craniocervical instability (CCI) in three cervical sagittal positions. This necessitated development of a reliable measurement protocol using upright, dynamic MRI (udMRI), to determine differences in the extent of motion between positions, and whether age and sex correlate with these measures.

MATERIALS AND METHODS

Deidentified udMRIs of 50 adults, referred for reasons other than CCI, were captured at three positions (maximal flexion, maximal extension and neutral). Images were analyzed, providing measures of basion-axial interval, basion-axial angle, basion-dens interval (BDI) and the Grabb-Oakes line (GOL) for all three positions (12 measures per participant). All measures were independently recorded by a radiologist and neurosurgeon to determine their reliability. Descriptive statistics, correlations, paired and independent t-tests were used. Mean (± 2 SD) identified the reference range for all four measures at each craniocervical position.

RESULTS

The revised measurement protocol produced inter-rater reliability indices of 0.69-0.97 (moderate-excellent). Fifty adults' (50% male; mean age 41.2 years (± 9.7)) reference ranges for all twelve measures were reported. Except for the BDI and GOL when moving between neutral and full flexion, significant extents of movement were identified between the three craniocervical positions for all four measures (p ≤ 0.005). Only a minor effect of age was found.

CONCLUSIONS

This is the first study to provide a rigorous standardized protocol for four diagnostic measures of CCI. Reference ranges are established at mid and ends of sagittal cervical range corresponding to where exacerbations of signs and symptoms are commonly reported.

Comparison between 2D TSE and 3D SPACE in the evaluation of craniocervical ligaments

PURPOSE

To evaluate the MRI findings of the craniocervical junction ligaments and compare the 2D TSE sequence and 3D SPACE sequence on cervical spine MRI.

METHODS

Eighty cervical spine MRIs were retrospectively analyzed, including 2D TSE and 3D SPACE sequences. The visibility and morphology of the transverse ligament (TL) and alar ligament (AL) were evaluated by two readers using a five-point grading scale for visibility (1 = not visible, 2 = barely visible, 3 = adequately visible, 4 = good visibility, 5 = excellent visibility) and a four-point grading scale for morphology (0 = homogeneous low SI with normal thickness, 1 = high SI with normal thickness, 2 = reduced thickness, 3 = full-thickness rupture or indistinguishable from surrounding structures). The grades of the two sequences were compared. Reader agreements were measured using the percentage of exact agreement.

RESULT

The visibility grade of TL was significantly higher in 3D, indicating better visualization. The morphology grade of TL was significantly lower in the 3D, indicating more normal-appearing ligament. The exact agreements of visibility and morphology grade of TL tended to be higher in 3D. On the other hand, there was no significant difference in visibility grade of AL between the two sequences. The morphological grade of AL was significantly higher in 3D. The agreement of the morphological grade of AL tended to be lower in 3D.

CONCLUSION

The utilization of 3D sequences significantly improves the visibility of TL and could potentially reduce false-positive diagnoses of ligament injury.

An anatomical and radiological study of the tectorial membrane and its clinical implications

The radiological image of an intact tectorial membrane (TM) became an important favorable prognostic factor for craniovertebral instability. This study visualized the fascial layers of the TM and adjacent connective tissues with clinical significance by micro-CT and histological analysis. The TM firmly attached to the bony surface of the clivus, traversed the atlantoaxial joint posteriorly, and was inserted to the body of the axis showing wide distribution on the craniovertebral junction. The supradental space between the clivus, dens of the axis, anterior atlantooccipital membrane, and the TM contained profound venous networks within the adipose tissues. At the body of the axis, the compact TM layer is gradually divided into multiple layers and the deeper TM layers reached the axis while the superficial layer continued to the posterior longitudinal ligament of the lower vertebrae. The consistent presence of the fat pad and venous plexus in the supradental space and firm stabilization of the TM on the craniovertebral junction was demonstrated by high-resolution radiologic images and histological analysis. The evaluation of the TM integrity is a promising diagnostic factor for traumatic craniovertebral dislocation.

Craniocervical Instability in Ehlers-Danlos Syndrome-A Systematic Review of Diagnostic and Surgical Treatment Criteria

STUDY DESIGN

Systematic review.

OBJECTIVE

Ehlers-Danlos Syndrome (EDS) comprises a spectrum of connective tissue disorders, which may be associated with cranio-cervical instability (CCI). There is a lack of consensus on diagnostic imaging parameters, indications, and outcomes of surgical treatment.

METHODS

This systematic review analyses the literature on diagnostic methods and/or criteria for CCI, screening the databases Ovid Medline, Embase, Cochrane Library, and PubMed. Articles were included based on the PRISMA guidelines and assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS) and according to their evidence level.

RESULTS

Sixteen articles, including 78 surgical patients, met the inclusion criteria. The main diagnostic measures for CCI were dynamic x-rays and CT imaging. Ten different radiographic parameters were reported, of which 4 were the most frequently applied for surgical decision-making: the clivo-axial angle (CXA), the Harris measurement, the Grabb-Mapstone-Oakes measurement, and the angular displacement of C1 to C2. The evidence level ranged between III and V and the article quality between 4 and 8 out of 9 stars on the NOS Scale.

CONCLUSIONS

There is a lack of high quality, prospective evidence regarding the evaluation of suspected CCI in patients with EDS. Based on our systematic review, we recommend that the CXA, Harris measurement, Grabb-Mapstone-Oakes measurement, and the angular displacement of C1 to C2 be used to evaluate suspected CCI in EDS patients. Surgical fixation of suspected CCI should only be performed in cases with clear radiographic presence of instability and concordant symptoms/signs. Consensus-based guidelines and care pathways are required.

Pathoanatomy, biomechanics, and treatment of upper cervical ligamentous instability: A literature review

BACKGROUND

Cervical spine instability broadly refers to compromise of the articular congruity. It can be stratified according to spinal level, functional compromise, and mechanism of instability. Conventional wisdom advocates for use of bracing and physical therapy with only a subset of patients proceeding to obtain surgical treatment.

OBJECTIVE

The purpose of this review article is to summarize the current state of knowledge on upper cervical ligamentous instability.

METHODS

The literature search was performed in Mendeley. Search fields were varied until redundant. All articles were screened by title and abstract and a preliminary decision to include an article was made. The full-text screening was performed on the selected articles. Any question regarding the inclusion of an article was discussed by 3 authors until an agreement was reached.

RESULTS

Many articles report on the etiological factors including ligamentous laxity, traumatic injury, syndrome instability, iatrogenic instability, congenital, and inflammatory causes. A few recent studies elucidate new findings regarding pathoanatomy through the use of finite element analysis. A few articles demonstrate the diagnosis and show that radiographs alone have a low diagnostic rate and that functional MRI may be able to better quantify instability. Conservative treatment has been described, but there are no outcome studies in the literature. Surgical treatment has been described in many different populations with good radiologic and clinical outcomes. Recently the use of preoperative 3D CT reconstruction has been described with radiographic and immediate postoperative patient-reported outcomes.

CONCLUSION

The presentation of upper cervical spinal instability can be asymptomatic, symptoms of isolated instability, symptoms of nerve irritation, vertebrobasilar insufficiency, or severe neurologic compromise. 3D fine element analysis models and motion-capture systems have the potential to increase our understanding of the pathoanatomic cascade in both traumatic and non-traumatic cases of upper cervical spinal instability. A few modalities on the horizon could increase diagnostic potential. More efforts are needed regarding the use of fine element analysis in understanding the pathoanatomic cascade, the long-term outcomes of children over a spectrum of syndromic causes, and the potential of preoperative virtual simulation to improve surgical outcomes.

Magnetic Resonance Imaging for Spine Emergencies

This article is devoted to the MR imaging evaluation of spine emergencies, defined as spinal pathologic conditions that pose an immediate risk of significant morbidity or mortality to the patient if not diagnosed and treated in a timely manner. MR imaging plays a central role in the timely diagnosis of spine emergencies. A summary of MR imaging indications and MR imaging protocols tailored for a variety of spinal emergencies will be presented followed by a review of key imaging findings for the most-encountered emergent spine pathologic conditions. Pathologic conditions will be broadly grouped into traumatic and atraumatic pathologic conditions. For traumatic injuries, a practical and algorithmic diagnostic approach based on the AO Spine injury classification system will be presented focused on subaxial spine trauma. Atraumatic spinal emergencies will be dichotomized into compressive and noncompressive subtypes. The location of external compressive disease with respect to the thecal sac is fundamental to establishing a differential diagnosis for compressive emergencies, whereas specific patterns of spinal cord involvement on MR imaging will guide the discussion of inflammatory and noninflammatory causes of noncompressive myelopathy.

Craniocervical Junction Visualization and Radiation Dose Consideration Utilizing Cone Beam Computed Tomography for Upper Cervical Chiropractic Clinical Application a Literature Review

Objectives

To highlight the detail obtained on a Cone Beam Computed Tomography (CBCT) scan of the craniocervical junction and its usefulness to Chiropractors who specialize in the upper cervical spine. A review of the dose considerations to patients vs radiography in a chiropractic clinical setting and to review the effective radiation dose to the patient.

Methods

A review of studies discussing cervical biomechanics, neurovascular structures, and abnormal radiographic findings, was discussed in relation to chiropractic clinical relevance. Further studies were evaluated demonstrating radiation dose to the patient from radiographs compared to CBCT.

Results

Incidental and abnormal findings of the craniocervical junction were shown to have superior visualization with CBCT compared to radiography. The radiation dose to the patient for similar imaging protocols to the craniocervical junction and cervical spine was equal or less utilizing CBCT when compared to radiographs.

Conclusions

The use of CBCT for visualization of the craniocervical junction and cervical spine in the chiropractic clinical setting allows for adjunctive visualization of the osseous structures which is germane to clinical protocol. Further with CBCT the effective dose to the patient is equal or less than similar imaging protocols utilizing radiographs to evaluate the craniocervical junction.

C1-C2 Dorsal Epidural Hematoma on Cervical Spine CT: A Novel Imaging Sign of Posterior Atlanto-Occipital Membrane Stripping Injury

Background and Purpose: Identify patients with a dorsal epidural hematoma at C1-C2 and examine the major craniocervical junction ligaments for injury on follow-up magnetic resonance imaging.

Materials and Methods: Adult and pediatric trauma patients who suffered a dorsal epidural hematoma at C1-C2 were identified using Nuance mPower software (Nuance Communications, United States). The cervical computed tomography and magnetic resonance imaging exams for these patients were reviewed for craniocervical junction osteoligamentous injuries. An age-matched control group was obtained.

Results: Eight trauma patients were identified with a dorsal epidural fluid collection at C1-C2. All patients with a dorsal epidural hematoma, who underwent follow-up cervical magnetic resonance imaging demonstrated a stripping injury of the posterior atlanto-occipital membrane from the C1 posterior arch with increased short tau inversion recovery signal in the posterior atlanto-occipital membrane complex. Disruption of additional major craniocervcial ligaments on magnetic resonance imaging was relatively common with the most frequently associated ligamentous injuries involving the tectorial membrane (five patients) followed by the alar ligaments and anterior altanto-occiptial membrane (four patients each). 

Conclusions: A C1-C2 dorsal epidural hematoma is a rare injury that may be identified on cervical spine computed tomography but may be easily overlooked by the radiologist. We propose that a C1-C2 dorsal epidural hematoma is a direct result of a significant hyperflexion-hyperextension force with subsequent stripping of the posterior atlanto-occipital membrane from the posterior C1 arch. Trauma patients with a C1-C2 dorsal epidural hematoma on cervical spine computed tomography should undergo a cervical magnetic resonance imaging examination to evaluate the integrity of the posterior atlanto-occipital membrane complex and remaining craniocervical junction ligaments for injury.

Occipital condylar avulsion fractures in the acute trauma setting: Stable or unstable injury?

BACKGROUND AND PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Longitudinal atlantoaxial dislocation associated with type III odontoid fracture due to high-energy trauma. Case report and literature review

INTRODUCTION

Traumatic upper cervical spine injuries are frequently associated with high-energy trauma. The potential injuries to vital organs associated to a possible neurological damage marks the severity of this pathology. The neurological structures can be affected by a primary injury, spinal cord, cranial nerves and spinal nerves; or secondary to a vascular compromise, mainly the vertebral arteries. The dislocation of the atlantoaxial joint causes an unstable cervical spine that could be often associated with fracture of the Atlas and Axis. Evidently, these have a high morbimortality rate.

CASE PRESENTATION

A young woman who suffered a severe polytrauma secondary to a motor vehicle collision was diagnosed with a sagittal plane atlantoaxial joint dislocation associated with a type III odontoid fracture, despite an adequate initial polytrauma management, the neurological damage was too critical, ultimately the decease of the patient.

DISCUSSION

The atlantoaxial joint dislocation is a rare condition of the upper cervical spine and is usually secondary to a high-energy traumatism. The disruption of the atlantoaxial ligaments originates the considered most unstable cervical spine lesion and with the highest mortality. Attributable to the kinetic the bone fracture of the Atlas and Axis are commonly related, specially the odontoid process. Early immobilization followed by surgical decompression and stabilization is primordial. Typically, these injuries have an ominous prognosis, that is aggravated if added a polytrauma affecting adjacent neurological structures and other vital organs.

"Supradental space sign" on cervical spine CT-a sign of tectorial membrane injury in adults trauma patients

BACKGROUND AND PURPOSE

The supradental space is a small, predominantly fat-filled recess superior to the atlanto-axial joint and inferior to the basion of the clivus that contains a small venous plexus. The posterior boundary of the supradental space is formed by the tectorial membrane, a stabilizing ligament of the craniocervical junction. The purpose of our study was to examine the imaging appearance of the supradental space in patients with tectorial membrane injury.

MATERIALS AND METHODS

Adult patients with tectorial membrane injury were identified utilizing keyword searches of radiology reports using Nuance mPower software. Age-matched positive and negative control groups were obtained. Two CAQ-certified neuroradiologists evaluated the cervical CT exams of these patients for supradental fat pad effacement from hematoma formation. The integrity of the osteoligamentous structures of the craniocervical junction was recorded on CT and MRI exams along with demographic information, clinical history, surgical management, and global outcome. Statistical analysis was performed.

RESULTS

Sixteen adults were diagnosed with tectorial membrane injury on cervical MRI. All patients with a visible supradental space demonstrated fat pad effacement and Hounsfield units consistent with hematoma formation. The positive and negative control groups demonstrated supradental fat pad effacement in 2/16 and 1/16 patients, respectively. A p-value of < 0.001 was obtained.

CONCLUSION

The "supradental space sign," defined as hematoma formation in the supradental space with effacement of the supradental fat pad is associated with tectorial membrane injury in adult trauma patients with sensitivity of 93.75% (95% confidence interval 69.77 to 99.84%) and specificity of 90.62% (95% confidence interval 74.98 to 98.02%).

Proposed Grading System for Posterior Atlantooccipital Membrane Complex Injuries on Cervical Magnetic Resonance Imaging

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.

Tectorial Membrane Injury, Frequently Identified in Adult Trauma Patients Who Undergo Occipital-Cervical Fusion for Craniocervical Instability

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.

Anatomic, functional, and radiographic review of the ligaments of the craniocervical junction

The craniocervical junction (CCJ) is a complex and unique osteoligamentous structure that balances maximum stability and protection of vital neurovascular anatomy with ample mobility and range of motion. With the increasing utilization and improved resolution of cervical magnetic resonance imaging, craniocervical injury is being more accurately defined as a spectrum of injury that ranges in severity from overt craniocervical disassociation to isolated injuries of one more of the craniocervical ligaments, which may also lead to craniocervical instability. Thus, it is vital for the radiologist and neurosurgeon to have a thorough understanding of the imaging anatomy and function of the CCJ.

Radiological and clinical features of traumatic atlanto-occipital dislocation

PURPOSE

We aimed to describe the findings of traumatic atlanto-occipital dislocation (AOD) on cervical spine CTs and differences leading to varying treatment of these patients.

METHODS

We retrospectively identified 20 adult patients with AOD from cervical spine CTs demonstrating fracture or fracture dislocations over 19 years at 2 major trauma centers. Medical records were reviewed and craniovertebral junction (CVJ) metrics measured on CT. Intubation, Glasgow Coma Scale (GCS), additional injuries, occiput/atlas/axis fracture, concurrent atlantoaxial subluxation, vascular injury on CT angiography, and ligamentous injury on MRI were noted.

RESULTS

Using the Traynelis Classification, eight patients had type 2 and eight patients type 3 AOD. Four of 5 patients who died within 14 days of CT had type 2 AOD. Three patients had medial/lateral AOD. Of the patients who survived initial injuries, a greater percentage who underwent surgical or halo fixation versus non-operatively treated patients had abnormal CVJ measurements including BDI (62.5% vs 0%), atlantoaxial subluxation (75% vs 14.3%), ligamentous injury (80% vs 66.7%), intubation (62.5% vs 28.6%), GCS<8 (62.5% vs 14.3%), and additional injuries (75% vs 71.4%) on presentation. MRI helped identify 2 cases of type 2 AOD and surgical decision making in 8 cases.

CONCLUSIONS

Types 2 and 3 were the most common, and type 2 is the deadliest type of AOD. A greater proportion of patients who undergo surgical or halo fixation have abnormal CT/MR findings with neurologic impairment at presentation. MRI aided detection of potentially missed type 2 AOD and was critical for surgical decision making.

Atlantoaxial rotatory subluxation/fixation and Grisel's syndrome in children: clinical and radiological prognostic factors

Atlantoaxial rotatory subluxation/fixation (AARS/F) is a rare cause of torticollis in children. The aim of our study is to investigate all possible clinical and radiological prognostic factors in children with AARS/F. We retrospectively reviewed all cervical spine CT scans of children with AARS/F treated in our Hospital over the last 15 years. AARS/F was classified according to Fielding and Hawkins classification and C1-C2 rotation-degree was calculated. Moreover, two orthopedic surgeons reviewed all clinical reports of these children. All patients were conservatively treated (cervical traction/neck collar). An early recovery was considered in patients with complete clinical/radiological healing at 3 months follow-up, while a late recovery was considered in patients with disease persistence or relapse at 3 months follow-up or earlier. Fifty-five patients with diagnosis of AARS/F were included in the study (mean age = 8.5 years old - 25F, 30M). In 9/55 subjects (16.4%), a late recovery was observed. The presence of a concomitant infection or inflammation in the head and neck region (Grisel's syndrome) was significantly associated with a late recovery (p < .001). Also, the type of AARS/F (p = .019), according to the Fielding and Hawkins classification, and C1-C2 rotation-degree (p = .027) were significantly correlated with the recovery time.Conclusion: In patients with AARS/F, the presence of a concomitant infection/inflammation in the head and neck region is the most important prognostic factor and it is associated with a late recovery. The Fielding and Hawkins classification and C1-C2 rotation-degree well correlate with patients' recovery time. What is Known: • Atlantoaxial rotatory subluxation/fixation (AARS/F) is a rare cause of torticollis in children and CT is the most useful imaging tool for diagnosis and classification of AARS/F. • Conservative treatments are effective in the majority of pediatric patients with AARS/F. What is New: • The presence of a concomitant infection/inflammation in the head and neck region associated with AARS/F (Grisel's syndrome) is the most important prognostic factor and it is associated with a late recovery. • C1-C2 rotation-degrees, as well as Fielding and Hawkins classification system, well correlate with patients' recovery time.

Cranio-Vertebral Junction Triangular Area: Quantification of Brain Stem Compression by Magnetic Resonance Images

(1) Background: Most of the currently used radiological criteria for craniovertebral junction (CVJ) were developed prior to the popularity of magnetic resonance images (MRIs). This study aimed to evaluate the efficacy of a novel triangular area (TA) calculated on MRIs for pathologies at the CVJ. (2) Methods: A total of 702 consecutive patients were enrolled, grouped into three: (a) Those with pathologies at the CVJ (n = 129); (b) those with underlying rheumatoid arthritis (RA) but no CVJ abnormalities (n = 279); and (3) normal (control; n = 294). TA was defined on T2-weighted MRIs by three points: The lowest point of the clivus, the posterior-inferior point of C2, and the most dorsal indentation point at the ventral brain stem. Receiver operating characteristic (ROC) analysis was used to correlate the prognostic value of the TA with myelopathy. Pre- and post-operative TA values were compared for validation. (c) Results: The CVJ-pathology group had the largest mean TA (1.58 ± 0.47 cm²), compared to the RA and control groups (0.96 ± 0.31 and 1.05 ± 0.26, respectively). The ROC analysis calculated the cutoff-point for myelopathy as 1.36 cm² with the area under the curve at 0.93. Of the 81 surgical patients, the TA was reduced (1.21 ± 0.37 cm²) at two-years post-operation compared to that at pre-operation (1.67 ± 0.51 cm²). Moreover, intra-operative complete reduction of the abnormalities could further decrease the TA to 1.03 ± 0.39 cm². (4) Conclusions: The TA, a valid measurement to quantify compression at the CVJ and evaluate the efficacy of surgery, averaged 1.05 cm² in normal patients, and 1.36 cm² could be a cutoff-point for myelopathy and of clinical significance.

Radiologic predictors of in-hospital mortality after traumatic craniocervical dissociation

BACKGROUND

Traumatic craniocervical dissociation (CCD) is the forcible dislocation of the skull from the vertebral column. Because most CCD patients die on scene, prognostication for those who arrive alive to hospital is challenging. The study objective was to determine if greater dissociation, based on radiologic measurements of CCD, is predictive of in-hospital mortality among patients surviving to the emergency department.

METHODS

All trauma patients arriving to our Level 1 trauma center (January 2008 to April 2019) with CCD were retrospectively identified and included. Transfers and patients without computed tomography head/cervical spine were excluded. Study patients were dichotomized into groups based on in-hospital mortality. Radiologic measurements of degree of CCD were performed based on the index computed tomography scan by an attending radiologist with Emergency Radiology fellowship training. Measurements were compared between patients who died in-hospital versus those who survived.

RESULTS

After exclusions, 36 patients remained: 12 (33%) died and 24 (67%) survived. Median age was 55 years (30-67 years) versus 44 (20-61 years) (p = 0.199). Patients who died had higher Injury Severity Score (39 [31-71] vs. 27 [14-34], p = 0.019) and Abbreviated Injury Scale head/neck score (5 [5-5] vs. 4 [3-4], p = 0.001) than survivors. The only radiologic measurement that differed between groups was greater soft tissue edema at mid C1 among patients who died (12.37 [7.60-14.95] vs. 7.86 [5.25-11.61], p = 0.013). Receiver operating characteristic curve analysis of soft tissue edema at mid C1 and mortality revealed 10.86 mm or greater of soft tissue width predicted mortality with sensitivity and specificity of 0.75. All other radiologic parameters, including the basion-dens interval, were comparable between groups (p > 0.05).

CONCLUSION

Among patients who arrive alive to hospital after traumatic CCD, greater radiologic dissociation is not associated with increased mortality. However, increased soft tissue edema at the level of mid C1, particularly 10.86 mm or greater, is associated with in-hospital death. These findings improve our understanding of this highly lethal injury and impart the ability to better prognosticate for patients arriving alive to hospital with CCD.

LEVEL OF EVIDENCE

Prognostic and Epidemiological, Level III.

Atlanto-occipital distraction injuries in survivors: craniometrics and associated ligamentous, spinal cord, and blunt cerebrovascular injury

PURPOSE

Newer classification systems for upper cervical spine trauma now include ligamentous injury in addition to fracture and dislocation patterns. Assessment of associated ligamentous injury, spinal cord injury (SCI), and blunt cerebrovascular injuries (BCVI) in patients with atlanto-occipital distraction injuries (AODI) are critical for management. We aim to determine the incidence of ligamentous injury, SCI, and BCVI in patients with AODI and assess how craniometrics perform in diagnosis of AODI.

MATERIALS AND METHODS

We performed an IRB-approved retrospective analysis of 35 cases of diagnosed AODI over a period of 8 years. Imaging was analyzed by two experienced neuroradiologists for craniometric measurements, ligamentous injury, SCI, and BCVI. Craniometric measurements were compared to 35 age-matched controls with normal atlanto-occipital joint.

RESULTS

Out of 35 patients diagnosed with AODI, 27 were adults and 8 belonged to pediatric age group. The mean age of presentation was 29.4 years with a male/female ratio of 22:13. The basion-dental interval (70.4%) and the combined condylar sum (74.1%) were the most sensitive craniometric measurements for diagnosis of AODI. Alar ligament (83%) and the tectorial membrane (89%) injuries were most commonly injured ligaments. Three adult patients sustained SCI and 10 patients had BCVI. Majority of BCVI involved the internal carotid artery followed by the vertebral artery.

CONCLUSIONS

The combination of craniometric indices with assessment of ligamentous injuries provides higher diagnostic accuracy for AODI. Alar ligament and tectorial membrane injuries have high association with AODI. There is high association of SCI and BCVI in AODI survivors.

Imaging of pediatric cervical spine trauma

While pediatric cervical spine injuries (CSI) are rare, they are associated with high morbidity and mortality and sometimes require expeditious surgical management. In this article, we aim to improve the diagnostic accuracy of pediatric CSI by reviewing normal pediatric cervical anatomy, typical pediatric CSI patterns, and common mimics of pediatric CSI. A literature review was conducted on pediatric CSI, its epidemiology, and the various imaging manifestations and mimics. The most common pediatric CSI occur in the upper cervical spine owing to the higher fulcrum and larger head at a young age, namely prior to age 9 years, while lower CSI occur more frequently in patients older than 9 years. While various craniocervical measurements may be utilized to identify craniocervical disruption, soft tissue injuries may be the only manifestation, thus making pediatric CSI difficult to diagnose on initial imaging. In the acute setting, CT cervical spine is an appropriate initial imaging modality for pediatric CSI evaluation. MRI serves as an additional tool to exclude or identify injuries when initial findings are equivocal. It is essential to recognize the unique anatomy and biomechanics of the pediatric spine and thus discern common pediatric CSI patterns and their mimics.

Recurrent traumatic atlantoaxial rotatory subluxation: Case report

Introduction

Atlantoaxial rotatory subluxation (AARS) is not uncommon in paediatric emergencies, however, the complications might be fatal. Long onset before presentation is correlated with higher recurrence and persistent deformity. There is no consensus on the treatment of AARS yet. Selected patients may benefit from conservative approaches; however, retention might be difficult, and subluxation may recur.

Presentation of case

A 6-year-old boy was admitted to our institution with AARS for three months before admission. Typical Cock-Robin position was observed. Computed tomography (CT) indicated AARS Fielding and Hawkins grade III. We treated the case conservatively by closed reduction and cervical traction using Gardner-Wells tongs. However, poor compliance resulted recurrence of subluxation, so we decided to fuse the atlantoaxial joint using transarticular screws, posterior wiring, and autologous bone grafting. Posterior fusion resulted in a satisfactory outcome, in which the wound healed accordingly. Six months of follow up examination revealed normal motoric and sensory function. The patient was able to perform daily activities with no significant issues.

Discussion

Patients with fixed deformity of more than three weeks have a higher rate for recurrence or persistent deformity, as reduction is harder and difficult to maintain. The use of posterior wiring alone is limited in maintaining reduction, while using transarticular screws alone is considered better in maintaining reduction; however, not providing it.

Conclusion

The use of posterior cervical fusion using C-wire, transarticular screws, and autologous bone grafting may be applied in recurrent case of AARS to ensure adequate reduction and fixation of the atlantoaxial joint.

•

AARS is not uncommon in the paediatric setting as the biomechanical property of the paediatric spine introduces more risk for dislocation.

•

A 6-year-old boy was admitted with AARS for three months before admission. After treated conservatively, the subluxation reoccurred. We decided to fuse the atlantoaxial joint.

•

Posterior cervical fusion using C-wire, transarticular screws, and autologous bone grafting may be applied in recurrent case of AARS to ensure adequate reduction and fixation of the atlantoaxial joint.

Skull Base-related Lesions at Routine Head CT from the Emergency Department: Pearls, Pitfalls, and Lessons Learned

Routine non-contrast material-enhanced head CT is one of the most frequently ordered studies in the emergency department. Skull base-related pathologic entities, often depicted on the first or last images of a routine head CT study, can be easily overlooked in the emergency setting if not incorporated in the interpreting radiologist's search pattern, as the findings can be incompletely imaged. Delayed diagnosis, misdiagnosis, or lack of recognition of skull base pathologic entities can negatively impact patient care. This article reviews and illustrates the essential skull base anatomy and common blind spots that are important to radiologists who interpret nonenhanced head CT images in the acute setting. The imaging characteristics of important "do not miss" lesions are emphasized and categorized by their cause and location within the skull base, and the potential differential diagnoses are discussed. An interpretation checklist to improve diagnostic accuracy is provided. ^©RSNA, 2019.

Imaging of cranio-cervical junction traumas

The craniocervical junction (CCJ) or upper cervical spine (UCS) has anatomic features and a biomechanics completely different from the other spinal segment of the spine. Several ligaments and muscles control its motion and function and ensure the maximum mobility and the visual and auditory spatial exploration. UCS traumas represent approximately one-third of all cervical spine injuries. Most of UCS traumas results from blows to the head and sudden deceleration of the body. Thanks to the improvement of the Advanced Trauma Life Support protocols dissociative injuries of CCJ have become less lethal onsite. In other less severe but unstable injuries, patients are neurologically intact at presentation, but they may deteriorate during the stay in hospital, with important clinical and medico-legal consequences. Knowing the peculiarities of UCS is fundamental for the early detection of imaging findings that influences the patient management and outcome. The classification of UCS traumas is mechanistic. More than in any other spinal segment, fractures of CCJ bones can occur without generating instability; on the contrary highly unstable injuries may not be associated with bone fractures. An early and correct diagnosis of occipito-cervical instability may prevent secondary neurological injury. The goal of imaging is to identify which patients can benefit of surgical stabilization and prevent secondary neurologic damage. Actual helical multidetector-CT (MDCT) offers high sensitivity and specificity for bone lesions and displacements in cervical spine traumas, but magnetic resonance imaging (MRI) is increasingly being used to evaluate soft tissues and ligaments, and mainly to identify possible spinal cord injury.

Magnetic resonance imaging of cervical ligamentous anatomy and traumatic ligamentous injuries

Cervical spine trauma accounts for majority of spinal injuries, and approximately one-third involve the craniocervical junction (CCJ). Due to its high sensitivity, magnetic resonance imaging (MRI) has become the standard tool for imaging suspected ligamentous injuries in an unstable spine and in patients with neurological deficits having a normal CT. The ligamentous anatomy of the CCJ is complex, and thorough knowledge is a prerequisite for accurate interpretation of the MRI findings. This pictorial essay aims to familiarise radiologists with the ligamentous anatomy, mechanisms of injury and MRI appearances of injuries in the cervical spine, with emphasis on the CCJ.

Age-related changes to the craniocervical ligaments in asymptomatic subjects: a prospective MR study

PURPOSE

The craniocervical junction (CCJ) is a complex of bony and ligamentous structure stabilizing CCJ. Nearly one-third of all traumatic injuries to the cervical spine involve the CCJ. Only little literature is available on this topic, and most of the studies are focused on anatomy, biomechanics or ligamentous injury in whiplash-associated disorders. We conducted a prospective study to investigate age-related changes in the craniocervical ligaments.

METHODS

We included asymptomatic volunteers between 16 and 99 years old who had no history of whiplash or other cervical trauma. Volunteers underwent a three-dimensional turbo spin-echo proton density-weighted sequence with variable flip-angle distribution focused on the craniocervical ligaments. The six main ligaments of the craniocervical junction were evaluated for grade of degeneration on a four-point scale by two independent readers, blinded for age and sex.

RESULTS

We included 102 volunteers. The mean age was 50.03 (16-94). Fifty-nine (58%) patients showed degeneration of at least one ligament of the CCJ. High-grade anomalous changes and multiligamentous involvement had a positive correlation with age (p < 0.001). The inter-rater agreement was fair to moderate, and the intra-rater agreement was moderate to substantial.

CONCLUSION

The craniocervical ligaments show a variable degree of signal intensity and thickness in asymptomatic adults. We postulate that these changes can be due to normal aging or due to repetitive microtrauma. We propose a new grading system to evaluate changes to the craniocervical ligaments in asymptomatic volunteers. These slides can be retrieved under Electronic Supplementary Material.

Change in rates of primary atlantoaxial spinal fusion surgeries in the United States (1993-2015)

OBJECTIVE

The objective of this study was to investigate revision burden and associated demographic and economic data for atlantoaxial (AA) fusion procedures in the US.

METHODS

Patient data from the National Inpatient Sample (NIS) database for primary AA fusion were obtained from 1993 to 2015, and for revision AA fusion from 2006 to 2014 using ICD-9 procedure codes. Data from 2006 to 2014 were used in comparisons between primary and revision surgeries. National procedure rates, hospital costs/charges, length of stay (LOS), routine discharge, and mortality rates were investigated.

RESULTS

Between 1993 and 2014, 52,011 patients underwent primary AA fusion. Over this period, there was a 111% increase in annual number of primary surgeries performed. An estimated 1372 patients underwent revision AA fusion between 2006 and 2014, and over this time period there was a 6% decrease in the number of revisions performed annually. The 65-84 year-old age group increased as a proportion of primary AA fusions in the US from 35.9% of all AA fusions in 1997 to 44.2% in 2015, an increase of 23%. The mean hospital cost for primary AA surgery increased 32% between 2006 and 2015, while the mean cost for revision AA surgery increased by 35% between 2006 and 2014. Between 2006 and 2014, the mean hospital charge for primary AA surgery increased by 67%; the mean charge for revision surgery over that same period increased by 57%. Between 2006 and 2014, the mean age for primary AA fusions was 60 years, while the mean age for revision AA fusions was 52 years. The mean LOS for both procedures decreased over the study period, with primary AA fusion decreasing by 31% and revision AA fusion decreasing by 24%. Revision burden decreased by 21% between 2006 and 2014 (mean 4.9%, range 3.2%-6.4%). The inpatient mortality rate for primary AA surgery decreased from 5.3% in 1993 to 2.2% in 2014.

CONCLUSIONS

The number of primary AA fusions between 2006 and 2014 increased 22%, while the number of revision procedures has decreased 6% over the same period. The revision burden decreased by 21%. The inpatient mortality rate decreased 62% (1993-2014) to 2.2%. The increased primary fusion rate, decreased revision burden, and decreased inpatient mortality determined in this study may suggest an improvement in the safety and success of primary AA fusion.

Traumatic Atlanto-Occipital Dissociation and Atlantoaxial Instability: Concomitant Ligamentous Injuries without Neurologic Deficit: A Case Report

CASE

A 35-year-old man was involved in a motor-vehicle collision and sustained multiple thoracoabdominal and extremity injuries. A high injury burden and a normal neurologic examination contributed to a delay in diagnosing a ligamentous, combined atlanto-occipital dissociation (AOD) and vertical atlantoaxial injury (AAI). Additional imaging revealed the combined injury, and the patient underwent an occipitocervical fusion.

CONCLUSION

To our knowledge, this is the first case of a simultaneous traumatic AOD and AAI without fracture in a neurologically intact patient. Knowledge of reliable and easily applied radiographic relationships is important to expeditiously diagnose potentially lethal yet easily overlooked occipitocervical injuries.

Traumatic combined vertical atlanto-occipital and atlanto-axial dislocations with 2-part fracture of the atlas: Two case reports

RATIONALE

To our knowledge, this is the first report of traumatic combined vertical atlanto-occipital dislocation (AOD) and atlanto-axial dislocation (AAD) with 2-part fracture of the atlas.

PATIENT CONCERNS

The first case was of a 31-year-old woman admitted to the emergency room comatose after a traffic accident. The second case was of a 21-year-old woman admitted to the emergency room comatose after a fall.

DIAGNOSES

Traumatic combined vertical AOD and AAD with 2-part fractures of the atlas was diagnosed using plain radiography, 2-dimensional computed tomography, and/or magnetic resonance imaging of the cervical spine.

INTERVENTION

The first patient received immediate intubation and cardiopulmonary resuscitation in the emergency room. The second patient also received immediate intubation in the emergency room. After her vitals stabilized, she underwent occipitocervical fusion with instrumentation.

OUTCOMES

The first patient died 2 days after the accident. The second patient remained quadriplegic in a ventilatory-dependent state at 1 year after surgery. She continues to receive comprehensive rehabilitation.

LESSONS

Immediate respiratory support and surgical stabilization are important for saving lives in this kind of extremely unstable and fatal complex upper cervical spine injury.

Comparison of imaging parameters pre- and post- reductive procedure for atlantoaxial dislocation via posterior fixation using pedicle screw and rod: a cross-sectional study

Background

To compare the imaging parameters pre- and post- reductive procedure for atlantoaxial dislocation via posterior fixation using pedicle screw and rod.

Methods

Thirty-seven patients suffering from atlantoaxial dislocation underwent posterior reduction and internal fixation by pedicle screw and rod. We measured pre-operative and post-operative atlantodental interval (ADI), clivus-canal angle (CCA), cervicomedullary angle (CMA), sum of lateral mass interspace (SLMI) of the operation and the control group. ADI, CCA, CMA, and SLMI between the pre-operative and post-operative conditions of the operation group and the control group were compared.

Results

The ADI, CCA, CMA, and SLMI in the pre-operative condition of the operation group were 8.3 ± 4.3 mm, 130.2 ± 14.2°, 133.8 ± 16.7°, and 3.7 ± 1.3 mm, respectively, those in the post-operative condition of the operation group were 1.0 ± 0.9 mm, 148.5 ± 9.4°, 156.0 ± 8.2°, and 8.0 ± 2.7 mm, respectively, while those in the control group were 1.2 ± 0.3 mm, 152.7 ± 5.3°, 160.2 ± 6.3°, and 4.5 ± 1.0 mm respectively. Post-operative ADI, CCA, CMA, and SLMI were statistically different (p < 0.01) from pre-operative assessments. The SLMI has no significant difference between the pre-operative condition and the control group. Post-operative SLMI was statistically different from that of the control group.

Conclusions

The lateral mass joints were widened after the anatomical reduction of atlantoaxial dislocation by pedicle screw and rod. Widening of the lateral mass exists in both atlantoaxial fusion and occipital-cervical fusion.

Tectorial membrane injury in adult and pediatric trauma patients: a retrospective review and proposed classification scheme

BACKGROUND AND PURPOSE

Traumatic tectorial membrane injuries have different radiologic presentations in adult versus pediatric patients. The purpose of this study was to identify and classify the different types of tectorial membrane injuries that occur in the adult and pediatric populations.

MATERIALS AND METHODS

Patients who suffered tectorial membrane injury were identified retrospectively using the keywords 'tectorial membrane," "craniocervical ligament tear/injury," and "atlanto-occipital dissociation" included in radiology reports between 2012 and 2018 using Nuance mPower software. All relevant imaging studies were reviewed by two certificates of additional qualification-certified neuroradiologists. Detailed descriptions of injuries were recorded along with any relevant additional findings, including clinical history.

RESULTS

Ten adults and six pediatric patients were identified with acute traumatic injuries of the tectorial membrane. Ninety percent of the adult patients sustained complete disruptions inferior to the clivus, or subclival, with 22% of tears at the level of the basion and 78% at the level of the odontoid tip. In contrast, 83% of pediatric patients suffered a stripping injury of the tectorial membrane located posterior to the clivus, or retroclival. Stretch injuries of the tectorial membrane were identified in 10% of adults and 17% of pediatric patients. The juvenile-type injury, which causes retroclival epidural hematoma, was determined to preferentially occur in patients less than or equal to 14 years of age with a high level of statistical significance (p value = 0.0014).

CONCLUSIONS

A classification system for tectorial membrane injuries is proposed based on this data: type 1-retroclival stripping injury (more common in pediatric patients); type 2a-subclival disruption at the basion and type 2b-subclival disruption at the odontoid (both more common in adult patients); and type 3-thinning of the tectorial membrane.

Morphometric changes at the craniocervical junction during childhood

OBJECTIVE

Current understanding of how the pediatric craniocervical junction develops remains incomplete. Measurements of anatomical relationships at the craniocervical junction can influence clinical and surgical decision-making. The purpose of this analysis was to quantitatively define clinically relevant craniocervical junction measurements in a population of children with CT scans that show normal anatomy.

METHODS

A total of 1458 eligible patients were identified from children between 1 and 18 years of age who underwent cervical spine CT scanning at a single institution. Patients were separated by both sex and age in years into 34 groups. Following this, patients within each group were randomly selected for inclusion until a target of 15 patients in each group had been reached. Each patient underwent measurement of the occipital condyle-C1 interval (CCI), pB-C2, atlantodental interval (ADI), basion-dens interval (BDI), basion-opisthion diameter (BOD), basion-axial interval (BAI), dens angulation, and canal diameter at C1. Mean values were calculated in each group. Each measurement was performed by two teams and compared for intraclass correlation coefficient (ICC).

RESULTS

The data showed that CCI, ADI, BDI, and dens angulation decrease in magnitude throughout childhood, while pB-C2, PADI, BAI, and BOD increase throughout childhood, with an ICC of fair to good (range 0.413-0.912). Notably, CCI decreases continuously on coronal CT scans, whereas on parasagittal CT scans, CCI does not decrease until after age 9, when it shows a continuous decline similar to measurements on coronal CT scans.

CONCLUSIONS

These morphometric analyses establish parameters for normal pediatric craniocervical spine growth for each year of life up to 18 years. The data should be considered when evaluating children for potential surgical intervention.

Tales from the Night:: Emergency MR Imaging in Pediatric Patients after Hours

Overnight in-house radiology has rapidly become an important part of contemporary practice models, and is increasingly the norm in pediatric radiology. MR imaging is an indispensable first-line and problem-solving tool in the pediatric population. This has led to increasingly complex MR imaging being performed "after hours" on pediatric patients. This article reviews the factors that have led to widespread overnight subspecialty radiology and the associated challenges for overnight radiologists, and provides an overview of up-to-date imaging techniques and imaging findings of the most common indications for emergent MR imaging in the pediatric population.