Pediatric cervical spine instability: evolving concepts

The pediatric cervical spine is structurally and biomechanically unique in comparison to adults. Guidelines to assess for cervical spine instability and standard of care treatments in the pediatric population have yet to be delineated. This is due to the rarity of the condition and the lack of multicenter data published on the topic. Our review explores the biomechanics of the pediatric cervical spine and highlights evolving concepts/research over the last several decades, with special attention to the Down syndrome and complex Chiari malformation cohorts.

Traumatic atlanto-occipital dislocation with successfully bystander resuscitation after cardiopulmonary arrest: A case report

This case report describes successful bystander cardiopulmonary resuscitation after a cardiopulmonary arrest due to a traffic accident, followed by early diagnosis and treatment of a traumatic atlanto-occipital dislocation, resulting in successful community reintegration.

[Atlanto-occipital dislocation-A challenge with respect to making the diagnosis and treatment]

BACKGROUND

The correct diagnosis and treatment of the atlanto-occipital dislocation (AOD) remains a major challenge.

OBJECTIVE

To evaluate the different radiological diagnostic criteria for AOD and discuss potential treatment strategies based on a case with AOD and additional fracture of the atlas.

MATERIAL AND METHODS

A 29-year-old male patient is presented who suffered from AOD with concomitant fracture of the anterior and posterior arches of the atlas with rotational atlantoaxial dislocation following an accident in forestry. The following parameters were evaluated for the diagnosis and assessment of postoperative reduction: Powers ratio, the X‑lines-method, Wackenheim line, basion-dens interval (BDI), basion-axial interval (BAI) and occipital condyle-C1 interval (CCI).

RESULTS

Stabilization was performed by occipitocervical spondylodesis from C0 to C2/3. For final reduction it was necessary to reduce the malrotation of the atlas. In the presented case, the revised CCI proved to be a sensitive and valid yet practical parameter. Powers' ratio and the BDI were less suited for assessing the diagnosis. The X‑lines-method, Wackenheim line and the BAI did not adequately detect the pathological situation.

DISCUSSION

The AOD is a severe injury requiring immediate correct diagnosis for later adequate treatment results. Among the published parameters, the revised CCI proved to be a practical and valid parameter to detect AOD. For definitive treatment, the operative occipitocervical stabilization is regarded as the method of choice.

Utility of Anterior Atlantodens Interval Widening on Cervical Spine CT for Assessing Transverse Atlantal Ligament Injury

STUDY DESIGN

Retrospective, cross-sectional.

OBJECTIVES

To identify trauma patients with confirmed tears of the transverse atlantal ligament on cervical MRI and measure several parameters of atlanto-axial alignment on cervical CT, including the anterior atlantodens interval, to determine which method is most sensitive in predicting transverse atlantal ligament injury.

METHODS

Adult trauma patients who suffered a transverse atlantal ligament tear on cervical MRI were identified retrospectively. The cervical CT and MRI exams for these patients were reviewed for the following: anterior and lateral atlantodens interval widening, lateral C1 mass offset, C1-C2 rotatory subluxation, and transverse atlantal ligament injuries on cervical MRI.

RESULTS

Twenty-six patients were identified with a tear of the transverse atlantal ligament on cervical MRI. Twelve percent of these patients demonstrated an anterior dens interval measuring greater than 2 mm, 26% of patients demonstrated lateral mass offset of C1 on C2 (average offset of 2.4 mm), 18% of patients demonstrated an asymmetry greater than 1 mm between the left and right lateral atlantodens interval, and one patient demonstrated atlanto-axial rotation measuring greater than 20%. Ten patients had an accompanying C1 burst fracture and eight patients had a C2 fracture. One patient demonstrated widening of the atlanto-occipital joint space greater than 2 mm indicative of craniocervical dissociation injury.

CONCLUSIONS

An anterior atlantodens interval measuring greater than 2 mm is an unreliable methodology to screen trauma patients for transverse altantal ligament injuries and atlanto-axial instability. Moreover, C1 lateral mass offset, lateral atlantodens asymmetry, and atlanto-axial rotation were all poor predictors of transverse atlantal ligament tears.

A Novel Treatment of Pediatric Atlanto-Occipital Dislocation with Nonfusion Using Muscle-Preserving Temporary Internal Fixation of C0-C2: Case Series and Technical Note

Study Design  Case series with surgical technical note. Objectives  This article reports experiences and results of muscle-preserving temporary C0-C2 fixation for the treatment of atlanto-occipital dislocation (AOD). Methods  AOD is a rare injury caused by high-energy trauma, occurring in less than 1% of pediatric trauma patients. Recommended treatment is C0-C2 fusion which, however, will result in significant loss of mobility in the craniocervical junction (CCJ), especially C1-C2 rotation. An alternative approach, with the ability of preserving mobility in the C1-C2 segment, is a temporary fixation that allows the ligaments to heal, after which the implants can be removed to regain function in the CCJ joints. By using a muscle-preserving approach and navigation for the C2 screws, a relatively atraumatic fixation of the CCJ can be achieved with motion recovery after implant removal. Results  We present two cases of AOD treated with temporary fixation. A 12-year-old boy involved in a frontal car collision, as a strapped back seat passenger, was treated with temporary C0-C2 fixation for 10 months. Follow-up at 11 months after implant removal included clinical evaluation, computed tomography, magnetic resonance imaging (MRI), and flexion-extension X-rays. He was free of symptoms at follow-up. The CCJ was radiographically stable and he had 45 degrees of C1-C2 rotation. A 7-year-old girl was hit by a car as she got off a bus. She was treated with temporary fixation for 4 months after which the implant was removed. Follow-up at 8 years included clinical evaluation and MRI in rotation. She was free of symptoms. The ligaments of the CCJ appeared normal and her C1-C2 rotation was 30 degrees. Conclusion  C0-C2 fixation without fusion allows the CCJ ligaments to heal in pediatric AOD. By removing the implants after ligament healing, rotation in the C1-C2 segment can be regained without subsequent instability. Both our patients tolerated the treatment well and were free of symptoms at follow-up. By using minimally invasive muscle-preserving technique and navigation, temporary fixation of the CCJ can be achieved with minimal damage to the soft tissues allowing recovery of almost normal function after implant removal.

Developing consensus for the management of pediatric cervical spine disorders and stabilization: a modified Delphi study

OBJECTIVE

Cervical spine disorders in children are relatively uncommon; therefore, paradigms for surgical and nonsurgical clinical management are not well established. The purpose of this study was to bring together an international, multidisciplinary group of pediatric cervical spine experts to build consensus via a modified Delphi approach regarding the clinical management of children with cervical spine disorders and those undergoing cervical spine stabilization surgery.

METHODS

A modified Delphi method was used to identify consensus statements for the management of children with cervical spine disorders requiring stabilization. A survey of current practices, supplemented by a literature review, was electronically distributed to 17 neurosurgeons and orthopedic surgeons experienced with the clinical management of pediatric cervical spine disorders. Subsequently, 52 summary statements were formulated and distributed to the group. Statements that reached near consensus or that were of particular interest were then discussed during an in-person meeting to attain further consensus. Consensus was defined as ≥ 80% agreement on a 4-point Likert scale (strongly agree, agree, disagree, strongly disagree).

RESULTS

Forty-five consensus-driven statements were identified, with all participants willing to incorporate them into their practice. For children with cervical spine disorders and/or stabilization, consensus statements were divided into the following categories: A) preoperative planning (12 statements); B) radiographic thresholds of instability (4); C) intraoperative/perioperative management (15); D) postoperative care (11); and E) nonoperative management (3). Several important statements reaching consensus included the following recommendations: 1) to obtain pre-positioning baseline signals with intraoperative neuromonitoring; 2) to use rigid instrumentation when technically feasible; 3) to provide postoperative external immobilization for 6-12 weeks with a rigid cervical collar rather than halo vest immobilization; and 4) to continue clinical postoperative follow-up at least until anatomical cervical spine maturity was reached. In addition, preoperative radiographic thresholds for instability that reached consensus included the following: 1) translational motion ≥ 5 mm at C1-2 (excluding patients with Down syndrome) or ≥ 4 mm in the subaxial spine; 2) dynamic angulation in the subaxial spine ≥ 10°; and 3) abnormal motion and T2 signal change on MRI seen at the same level.

CONCLUSIONS

In this study, the authors have demonstrated that a multidisciplinary, international group of pediatric cervical spine experts was able to reach consensus on 45 statements regarding the management of pediatric cervical spine disorders and stabilization. Further study is required to determine if implementation of these practices can lead to reduced complications and improved outcomes for children.

Atlanto-occipital dislocation with concomitant severe traumatic brain injury: A retrospective study at a level 1 trauma center

BACKGROUND

Traumatic atlanto-occipital dislocation (AOD) is a life-threatening injury. Although traumatic brain injury (TBI) is associated with increased mortality in AOD patients, a detailed individual analysis of these patients is lacking in the literature.

METHODS

Patients ≥16 years old who were diagnosed of AOD with concomitant severe TBI from 2010 to 2020 were included in this retrospective study. We examined the epidemiology, injury mechanisms, associated injuries, and outcomes of these patients.

RESULTS

Eight patients were included. Six patients died before any intervention could be performed, and two patients underwent an occipito-cervical fixation, showing a notorious neurologic improvement on follow-up. Cardiorespiratory arrest (CRA) was a strong predictor of subsequent death. CT signs of diffuse axonal injury (DAI) were present in most patients and were confirmed by magnetic resonance imaging (MRI) in survivors. Although TBI was not the main cause of death, it was responsible for the delayed neurological improvement and deferred stabilization. The average sensitivity of the different used methodologies for AOD diagnosis ranged from 0.50 to 1.00, being the Basion Dens Interval (BDI) and the Condyle-C1 interval (CCI) sum the most reliable criteria. Non-survivors tended to show greater distraction measurements. The high incidence of condylar avulsion fractures suggests that their visualization on the initial CT study should heighten the suspicion for AOD.

CONCLUSIONS

Our data suggest that patients with AOD and concomitant severe TBI might be salvageable patients. In those who survive beyond the first hospital days and show neurological improvement, surgical treatment should be performed as they can achieve an important neurologic recovery.

Referencing for anterior atlantoaxial trans-articular osteosynthesis: a radiological study and proposal of a decisional algorithm

PURPOSE

Anterior trans-articular C1-C2 screw placement can be considered as a surgical alternative in different conditions affecting the atlantoaxial region. While its rigidity is similar to posterior Magerl and Harms techniques, it also provides some surgical advantages. However, the literature lacks papers exhaustively describing indication criteria, surgical steps, and pitfalls.

METHODS

This is a radiological study on 100 healthy subjects. Thin-layer CT scans of the craniovertebral junction were retrieved from the institutional database. The coronal inclination of the C1-C2 joint rim and the depth of the entry point of the screw with respect to the anterior profile of C2 were measured. The antero-posterior and the medio-lateral surgical corridors for the screw placement, and the wideness of the target area on the upper surface of C1 were also measured.

RESULTS

The multivariate analysis showed that the coronal inclination of the C1-C2 articular joint rim strongly influences the surface extension of the C1 target area; the depth of the entry point and the C1-C2 articular rim inclination seem to be independent factors in influencing both the medio-lateral and the antero-posterior surgical corridors wideness. A decisional algorithm on whether to perform an anterior or posterior approach to the atlantoaxial region was also proposed.

CONCLUSIONS

We can conclude that, as much as the C1-C2 articular rim is tending to the horizontal line, and as deeper is the entry point of the screw on the anterior profile of C2, as easier the anterior C1-C2 trans-articular screw placement will result.

Atlanto-occipital dislocation in a child: a challenging diagnosis. Illustrative case

BACKGROUND

Atlanto-occipital dislocation (AOD) is a highly unstable injury of the osseoligamentous complex at the craniocervical junction that is more common in children. Its diagnosis remains a challenging process that must integrate clinical presentation and radiological criteria.

OBSERVATIONS

A 9-year-old child presented with severe craniocervical trauma (Glasgow Coma Scale score 6) and cardiorespiratory arrest on-site. Prompt resuscitation on-site and transfer to the university hospital were performed, and a computed tomography (CT) scan showed a subarachnoid hemorrhage around the brainstem and a retroclival hematoma. Most of the radiological criteria on CT scans for AOD were negative, except for the occipital condyle–C1 interval, and further imaging with magnetic resonance imaging permitted the diagnosis of AOD with rupture of both the tectorial membrane and the transverse ligament. Occipital-cervical Oc-C1–2 fixation was performed. The neurological outcome was excellent, with full recovery 6 months after the trauma.

LESSONS

AOD should be suspected in all high-intensity trauma in children, especially if the clinical presentation includes cardiorespiratory arrest and other brainstem and/or upper cervical cord symptoms along with premedullary subarachnoid hemorrhage. Understanding the ligamentous nature of the injury resulting in “normal” radiographs or CT scans is important to avoid underdiagnosing AOD, which can have detrimental consequences.

Occult craniocervical dissociation on cervical CT: an under-appreciated presentation of craniocervical trauma requiring occipital cervical fusion

BACKGROUND AND PURPOSE

Craniocervical dissociation is a rare and life-threatening injury that results from a significant hyperflexion-hyperextension force. Occult craniocervical dissociation is defined as an unstable craniocervical injury in the absence of atlanto-occipital joint space widening or other skull base line abnormality. The early and accurate diagnosis of craniocervical dissociation is crucial since the early diagnosis and subsequent stabilization with occipital-cervical fusion has been shown to reduce neurologic morbidity and mortality. Several normative skull base lines have been developed to predict craniocervical dissociation. The purpose of our study was to measure the atlanto-occipital joint space and four other common skull base lines in patients who underwent occipital-cervical fusion for post-traumatic craniocervical instability.

MATERIALS AND METHODS

Patients who underwent occipital-cervical fusion for craniocervical injury were identified retrospectively using a keyword search of radiology reports using Nuance mPower software. The cervical CT and MRI exams for these patients were reviewed and the atlanto-occipital joint space, Powers ratio, Wackenheim line, posterior axial line, and basion dens interval were measured. Detailed descriptions of craniocervical ligament injuries on MRI were recorded along with patient demographic information, clinical history, management, and outcome.

RESULTS

Nine adult patients who underwent occipital-cervical fusion for an acute craniocervical injury were identified. Six patients demonstrated an atlanto-occipital joint space measuring 2 mm or less on cervical spine CT with no additional abnormality in the Powers ratio, Wackenheim line, posterior axial line, or basion-dens interval. Three patients demonstrated widening of the atlanto-occipital joint space with two patients demonstrating an abnormality in at least two additional skull base lines. Clinical outcomes were variable with nearly half of the patients demonstrating persistent neurologic deficits, including one quadriplegic patient.

CONCLUSIONS

A normal atlanto-occipital joint space and skull base line measurements on cervical CT demonstrated a low predictive value for detecting unstable craniocervical injuries. Occult craniocervical dissociation was present in two-thirds of patients who underwent occipital cervical fusion for acute, craniocervical trauma. A high clinical and radiologic index of suspicion for craniocervical trauma with subsequent follow-up cervical MRI to directly evaluate ligamentous integrity is necessary to accurately diagnose and triage patients with high velocity trauma.

Unilateral atlanto-occipital injury: A case series and detailed radiographic description

Context

Atlanto-occipital dissociation is a highly lethal ligamentous injury at the craniocervical junction (CCJ). Previous studies have described rare cases of milder forms of atlanto-occipital injury (AOI) which might be managed nonoperatively, but there is a paucity of literature on this subject.

Aims:

We retrospectively reviewed our institutional experience to characterize the injury patterns, treatments, and clinical courses of patients with unilateral AOI.

Methods:

We included patients with radiographic evidence of unilateral occipitocervical joint capsular disruption, distraction, or edema ± injury of the apical ligament, tectorial membrane, anterior atlanto-occipital membrane, posterior atlanto-occipital membrane, alar ligaments, or cruciate ligament. The long-term outcomes were gathered from medical records, and six patients were available for Neck Disability Index via phone call at the time of the study.

Results:

Eight patients were included in the study. The mean age was 45.1 years ± 26.5. Causes of trauma included motor vehicle collision for five patients (5/8, 62.5%), falls for two (2/8, 25), and assault for one (1/8, 12.5%). All patients had a widened condyle-C1 interval >2 mm. Three patients underwent occipitocervical fusion, one patient underwent atlantoaxial fusion, and another received subaxial fusions for other injuries. Three patients underwent no surgical intervention. All patients were seen at least once as an outpatient following hospital discharge. There were no delayed neurologic injuries or deaths.

Conclusions:

We propose that ligamentous injury at the CCJ functions more as a spectrum rather than dichotomous diagnosis, of which a subset can likely be safely managed nonoperatively.

Predicting clinical outcomes using morphometric changes in adults with complex Chiari malformation undergoing occipitocervical fusion with or without ventral decompression: patient series

BACKGROUND

The authors assessed the connection between clinical outcomes and morphometrics in patients with complex Chiari malformation (CM) who have undergone posterior fossa decompression (PFD) and subsequent occipitocervical fusion (OCF) with or without ventral decompression (VD).

OBSERVATIONS

The authors retrospectively reviewed 33 patients with CM aged over 21 years who underwent PFD and OCF with or without endoscopic endonasal odontoidectomy at the authors’ institution (21 OCF only and 12 OCF + VD). Clivoaxial angle (CXA), pB-C2 (perpendicular line to the line between the basion and C2), atlantodental interval (ADI), basion-dens interval (BDI), basion-axial interval (BAI), and C1 canal diameter were measured on preoperative and approximately 3-month postoperative computed tomography or magnetic resonance imaging scans. Common symptoms included headache, paresthesia, and bulbar symptoms. Clinical improvement after surgery was observed in 78.8% of patients. CXA, ADI, and BDI all significantly increased after surgery, whereas pB-C2 and BAI significantly decreased. OCF + VD had a significantly more acute CXA and longer pB-C2 preoperatively than OCF only. Patients who clinically improved postoperatively showed the same significant morphometric changes, but those who did not improve showed no significant morphometric changes.

LESSONS

Patients showing improvement had greater corrections in skull base morphometrics than those who did not. Although there are various mutually nonexclusive reasons why certain patients do not improve after surgery, smaller degrees of morphometric correction could play a role.

Concomitant atlantoaxial and atlanto-occipital rotatory dislocation in children: Radiological features, diagnostic pitfalls, and long-term outcome

While the pathological manifestation of atlantoaxial rotatory dislocation has been well described in the medical literature, the combined dislocation of the atlantoaxial and atlanto-occipital joints, or OAARD - short for occipital-atlantoaxial rotatory dislocation - is a condition which has been poorly elucidated and probably underdiagnosed. We believe that the pathogenesis of combined atlantoaxial and atlanto-occipital dislocation is most likely a result of untreated atlantoaxial rotatory dislocation leading to chronic secondary compensation measures occurring at the occiput-C1 joints. Unique clinical and radiological features lead to difficulty in diagnosis, and conventional treatment algorithms may not apply. This paper describes a combination of clinical and radiological features which can help clinicians correctly diagnose and treat OAARD.

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.

Traumatic Atlanto-Occipital Dislocation-A Comprehensive Analysis of All Case Series Found in the Spinal Trauma Literature

BACKGROUND

Traumatic atlanto-occipital dislocation (TAOD) is one of the most devastating traumatic injuries, generally associated with immediate death after high-energy trauma. The aim of this study was to perform a systematic literature review of all cases series of TAOD and present the current state of this entity.

METHODS

A systematic literature review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only case series with at least 5 cases were included in the analysis. We focused on survival rates, diagnostic methods, delays in diagnosis, outcomes, and cases successfully treated nonoperatively.

RESULTS

A total of 17 articles were included (16 retrospective and 1 prospective study) with 341 patients. Six studies included pediatric patients only. The mean Glasgow Coma Scale at admission was ≤8 in all studies. Many different diagnostic criteria were used, but none of them had high accuracy. The overall mortality rate was 34.8%, but the studies' designs were heterogeneous (some included only survivors). A high rate of concomitant traumatic brain injury was documented in some studies. We found it interesting that some patients were treated with cervical immobilization (37/341; 10.8%), which was generally used in less unstable injuries; however, the majority of patients were managed with an occipito-cervical fusion (193/341; 56.5%).

CONCLUSIONS

TAOD is a devastating traumatic injury, with a high mortality rate. An MRI may be recommended when there are subtle findings of TAOD and a normal computed tomography scan, such as subarachnoid hemorrhage in the posterior fossa, upper cervical injuries, or consistent neurological findings. Further studies are necessary to identify patients with mild MRI findings and TAOD that may be managed nonoperatively.

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.

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.

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.

The occipitoatlantal capsular ligaments are the primary stabilizers of the occipitoatlantal joint in the craniocervical junction: a finite element analysis

OBJECTIVE

There is contradictory evidence regarding the relative contribution of the key stabilizing ligaments of the occipitoatlantal (OA) joint. Cadaveric studies are limited by the nature and the number of injury scenarios that can be tested to identify OA stabilizing ligaments. Finite element (FE) analysis can overcome these limitations and provide valuable data in this area. The authors completed an FE analysis of 5 subject-specific craniocervical junction (CCJ) models to investigate the biomechanics of the OA joint and identify the ligamentous structures essential for stability.

METHODS

Isolated and combined injury scenarios were simulated under physiological loads for 5 validated CCJ FE models to assess the relative role of key ligamentous structures on OA joint stability. Each model was tested in flexion-extension, axial rotation, and lateral bending in various injury scenarios. Isolated ligamentous injury scenarios consisted of either decreasing the stiffness of the OA capsular ligaments (OACLs) or completely removing the transverse ligament (TL), tectorial membrane (TM), or alar ligaments (ALs). Combination scenarios were also evaluated.

RESULTS

An isolated OACL injury resulted in the largest percentage increase in all ranges of motion (ROMs) at the OA joint compared with the other isolated injuries. Flexion, extension, lateral bending, and axial rotation significantly increased by 12.4% ± 7.4%, 11.1% ± 10.3%, 83.6% ± 14.4%, and 81.9% ± 9.4%, respectively (p ≤ 0.05 for all). Among combination injuries, OACL+TM+TL injury resulted in the most consistent significant increases in ROM for both the OA joint and the CCJ during all loading scenarios. OACL+AL injury caused the most significant percentage increase for OA joint axial rotation.

CONCLUSIONS

These results demonstrate that the OACLs are the key stabilizing ligamentous structures of the OA joint. Injury of these primary stabilizing ligaments is necessary to cause OA instability. Isolated injuries of TL, TM, or AL are unlikely to result in appreciable instability at the OA joint.

Rigid Internal Fixation for Traumatic Cranio-Cervical Dissociation in Infants and Young Children

STUDY DESIGN

Retrospective review.

OBJECTIVE

Evaluate radiographic and clinical outcomes for infants and children, who underwent rigid occipito-cervical fixation for traumatic craniocervical dissociation (tCCD).

SUMMARY OF BACKGROUND DATA

Traumatic craniocervical dissociation is devastating. Children are at high risk but make up a large number of survivors. Non-rigid fixation has traditionally been favored over screw and rod constructs due to inherent challenges involved with instrumenting the pediatric craniocervical junction. Therefore, outcomes for rigid occipito-cervical instrumentation in infants and young children with tCCD remain uncertain.

METHODS

Retrospective review of children who survived tCCD between 2006 and 2016 and underwent rigid occipito-cervical fixation.

RESULTS

Fifteen children, from 8 months to 8 years old (mean, 3.8 yr), were either a passenger (n = 11) or a pedestrian (n = 4) in a motor vehicle accident. Seven patients had weakness: five with quadriplegia, one with hemiparesis, and one with bilateral upper extremity paresis. Ten patients had concurrent C1-2 instability. At last follow-up, four patients had improved motor function: one with bilateral upper extremity paresis and one with hemiparesis regained full strength, one with quadriplegia regained function on one side while another regained function in bilateral upper extremities. All underwent rigid posterior occipito-cervical fixation, with two patients requiring additional anterior and posterior fixation at non-contiguous levels. Fourteen patients were stable on flexion-extension x-rays at a mean follow-up of 31 months (9-1 yr or longer, 7-2 yr or longer). There were no cases of deformity, growth disturbance, or subaxial instability.

CONCLUSION

Children who survive tCCD may regain function after stabilization. Rigid internal rod and screw fixation in infants and young children safely provided long-term stability. We advocate using C2 translaminar screws to exploit the favorable anatomy of pediatric lamina to minimize the risks of occipitocervical (OC) instrumentation.

LEVEL OF EVIDENCE

4.

Atlanto-Occipital Dislocation: A Case Report

Patients with atlanto-occipital dislocation (AOD) are increasingly being transported to emergency rooms, alive, by the improved pre-hospital emergency rescue system. The author reports a fatal case of AOD with severe neurovascular injuries following a high-speed pedestrian collision. Therefore, nowadays, neurosurgeons can expect an increase in the occurrence of such cases; an early diagnosis and prompt occipitocervical fusion can save lives. This report reviews the current concepts of AOD in mild to fatal conditions.

Traumatic Occipitocervical Distraction Injuries in Children: A Systematic Review

BACKGROUND

Occipitocervical distraction injuries (OCDI) in children occur on a wide spectrum of severity, and decisions about treatment suffer from a lack of rigorous guidelines and significant inter-institutional variability. While clear cases of frank atlanto-occipital dislocation (AOD) are treated with surgical stabilization, the approach for less severe cases of OCDI is not standardized. These patients require a careful assessment of both radiographic and clinical criteria, as part of a complex risk-benefit analysis, to establish whether occipitocervical fusion (OCF) is indicated. Here, we performed a systematic review of the literature that describes traumatic OCDI in children < 18 years of age.

SUMMARY

We performed a systematic review, according to PRISMA guidelines, of children < 18 years of age presenting with traumatic etiologies of OCDI. We searched PubMed to identify papers congruent with these criteria. Exclusion criteria included (1) reports on atraumatic causes of OCDI and (2) studies with insufficient clinical and radiographic details on individual patients. We identified 16 reports describing a total of 144 patients treated for pediatric traumatic OCDI. Based on the synthesis of these findings and the collective experience of the authors, we present the demographic, clinical, and radiographic factors that underlie OC instability, which we hope will serve as components of a grading system in the future. We considered various clinical and radiographic findings including: (1) the mechanism of injury, (2) the patient's age, (3) CT/CT angiography of head and neck findings and parameters, (4) MRI findings, and (5) neurological exam, for the purpose of determining the severity of the OCDI and offering treatment guidelines based on the summative risk of underlying OC instability. Key Messages: OCDI is a potentially devastating injury, especially in children. Although missing the diagnosis can have potentially catastrophic consequences, reverting to surgical fixation in less severe cases can subject children to unnecessary operative risk and permanently reduce their range of motion. After reviewing all the available reports of pediatric traumatic OCDI in the neurosurgical literature, we propose an outline of clinical and radiographic factors influencing underlying OC instability that could be incorporated into a grading scale to guide treatment. We hope this study stimulates discussion on the standardization of treatment for pediatric OCDI.

The timing of fusion surgery for clival chordoma with occipito-cervical joint instability: before or after tumor resection?

Clival chordoma with occipito-cervical (OC) joint invasion can result in preoperative and postoperative instability. The authors investigate the appropriate timing of OC fusion to prevent instability-, fusion-, and surgery time-related morbidity. Twenty-two consecutive patients underwent surgery for clival chordoma from December 2008 to September 2014. OC fusion was performed for patients with OC joint invasion and instability due to preoperative destruction of the occipital condyle or extensive postoperative condylectomy. The data in relation to OC joint instability, fusion, and surgery time were analyzed retrospectively and compared between OC fusion before and after tumor resection. Of the 22 patients, 8 with tumor invasion of the OC joint underwent OC fusion. OC fusion was performed after tumor resection in one-stage for four patients and before tumor resection in two-stage for four patients. There was OC joint instability from tumor destruction of the occipital condyle in seven patients (87.5%). Patients with OC fusion after tumor resection encountered complications such as surgery site wound dehiscence, encephalitis, and cardiac arrest with consequent mortality in one patient. These complications were avoided in subsequent patients where OC fusion was performed before tumor resection. There were no differences in the extent of tumor resection between OC fusion before and after tumor resection. Two-stage OC fusion before tumor resection can reduce instability-, fusion-, and surgery time-related morbidity and achieve feasible tumor resection when OC joint instability is expected. The extent of tumor invasion and brain stem compression should be considered when fusion precedes tumor resection.

Measurements in cervical vertebrae CT of pediatric cases: normal values

PURPOSE

This study aims to determine the normal limits of atlanto-dental interval (ADI), basion-dens interval (BDI), basion-cartilaginous dens interval (BCDI), and prevertebral soft tissue thickness (PVSTT) according to age groups for normal pediatric cases.

MATERIALS AND METHODS

CT images of 256 pediatric patients aged between 1 and 15 years were retrospectively evaluated. ADI, BDI, BCDI and PVSTT measurements were performed.

RESULTS

Upper normal limit (UNL) values for ADI were 2.65-4.8 mm. UNL values for PVSTT were found to be 6.9 mm at C1 level, 6.7 mm at C2 level, 9.3 mm at C3 level, 14.2 mm at C4 level, 14.1 mm at C5 level, 13.8 mm at C6 level and 12.8 mm at C7 level. The maximum value of BDI in the group with non-ossified os terminale was 12 mm, and in the group with ossified os terminale it was 10 mm. The UNL of BCDI determined for females was 5.1 mm, while the UNL for males was 5.6 mm.

CONCLUSION

We propose the obtained values as the UNL values for ADI, BDI, BCDI and PVSTT on CT images in the pediatric population from 1 to 15 years.

Safe management of acute cervical spine injuries

Cervical spine injuries are frequent and often caused by a blunt trauma mechanism. They can have severe consequences, with a high mortality rate and a high rate of neurological lesions.Diagnosis is a three-step process: 1) risk assessment according to the history and clinical features, guided by a clinical decision rule such as the Canadian C-Spine rule; 2) imaging if needed; 3) classification of the injury according to different classification systems in the different regions of the cervical spine.The urgency of treatment is dependent on the presence of a neurological lesion and/or instability. The treatment strategy depends on the morphological criteria as defined by the classification. Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170076.

Failure of the Condyle-C1 Interval Method to Diagnose Atlanto-occipital Dislocation in the Presence of an Associated Atlanto-axial Dislocation: A Case Report

Atlanto-occipital dislocation (AOD) is a craniocervical injury that has serious neurological consequences and is often fatal. High-speed blunt trauma, such as motor vehicle accidents, that extend and put traction on the head can cause this injury. The current recommendation for diagnosis is to measure the condyle-C1 interval (CCI) using a computed tomography (CT) scan in the coronal plane and more recently in the sagittal plane. We report the case of a patient who suffered a motor vehicle accident and had concomitant AOD and atlanto-axial dislocation. In this particular case, the CCI method failed to diagnose AOD and the diagnosis was made using the basion-dens interval (BDI) and other methodologies, as well as the presence of ligamentous disruption at the craniovertebral junction (CVJ) on magnetic resonance imaging (MRI).

A 19-year-old female suffered a motor vehicle accident in which she was ejected from the car. Her neck was immobilized on the scene and she was brought to the emergency department complaining of neck pain. CT of the cervical spine showed concomitant atlanto-occipital and atlanto-axial dissociation. MRI of the cervical spine confirmed the diagnosis with total ligamentous disruption at the CVJ and distraction of the atlanto-axial joints bilaterally. While the CCI was normal, the BDI was diagnostic of AOD.

The current recommendations for using the CCI interval method may not diagnose AOD in the presence of associated atlanto-axial dislocation. Other methodologies should be employed including BDI and basion-axial interval (BAI) as well as MR imaging showing ligamentous disruption.

Atlanto-Occipital Rotatory Dislocation: A Case Report and Systematic Review

BACKGROUND

Atlanto-occipital rotatory dislocation (AORD) has rarely been reported in the literature; for this reason, the clinicoradiologic characteristics of this injury are not well described.

METHODS

We describe the case of a 67-year-old man who sustained a cervical spine trauma. He reported only neck pain and was neurologically intact. A computed tomography scan showed a rotatory displacement of the atlanto-occipital joints associated with a widened condylar-C1 interval; in addition, magnetic resonance imaging showed injuries to the stabilizing ligaments of this area. A systematic literature review was also performed to identify previous cases of patients with AORD.

RESULTS

The patient was treated with craniocervical fixation from occipital to C1, achieving a good outcome. The literature review yielded 9 cases of patients with AORD. Compared with patients with atlanto-occipital dislocation, patients with rotatory dislocations have a less severe degree of displacement of the atlanto-occipital joints and better clinical outcome.

CONCLUSIONS

Compared with previously classified atlanto-occipital dislocations, AORD is an independent and unique variation. AORD presents with different biomechanical, clinicoradiologic, and prognostic characteristics and represents an important addition to the spectrum of atlanto-occipital dislocation injuries.

A Modified Technique for Occipitocervical Fusion Using Compressed Iliac Crest Allograft Results in a High Rate of Fusion in the Pediatric Population

BACKGROUND

In children, high rates of occipitocervical (OC) fusion have been demonstrated with the use of rigid instrumentation in combination with harvested autograft, with or without bone morphogenetic protein (BMP). Historically, the use of allograft materials demonstrated inferior OC fusion outcomes compared with autograft. However, autograft harvest harbors an increased risk of patient morbidity, and the use of BMP is costly and controversial in children. Thus, there remains a need for safer, less costly, yet efficacious techniques for OC fusion in the pediatric population.

METHODS

We retrospectively reviewed the charts of patients younger than 21 years of age who underwent OC fusion with structural allograft placement at our institution from 2010 to 2015. Data collected included age, sex, follow-up duration, fusion outcomes, and postoperative complications.

RESULTS

A total of 19 patients (8 female and 11 male) underwent OC fusion with our surgical technique. Mean age was 8.5 ± 4.3 years. Radiographic follow up data were available for 18 of 19 patients. One patient was lost to clinical follow up but had radiographic confirmation of fusion. Thus, 18 of 18 (100%) of patients with radiographic follow-up achieved successful arthrodesis as determined by computed tomography. Median duration to documented fusion was 4.5 months. Clinical follow-up was available for 17 of 19 patients and was on average 18.8 ± 13.5 months. One patient required reoperation for graft fracture 8 months after radiographic confirmation of successful fusion. There were no vertebral artery injuries or other postoperative complications.

CONCLUSIONS

We demonstrate a modified technique for OC fusion in children with unique structural allograft shaping and affixation, leading to excellent fusion outcomes at follow up. This technique obviates the need for autograft harvest or BMP, and may decrease postoperative morbidity.

Condylar Joint Fusion and Stabilization (by Screws and Plates) in Nontraumatic Atlanto-Occipital Dislocation: Technical Report of 2 Cases

BACKGROUND

Nontraumatic spontaneous atlanto-occipital dislocation (AOD) is rare. In this report, we discuss the technical steps of condylar joint fusion and stabilization (by screws and plates) in nontraumatic AOD. To the best of our knowledge, it is the first report of such techniques.

MATERIAL AND METHODS

A young girl and a young man with progressive quadriparesis due to nontraumatic spontaneous atlanto-occipital dislocation were managed by microsurgical reduction, fusion, and stabilization of the joint by occipital condylar and C1 lateral mass screw and plate fixation after mobilization of vertebral artery.

RESULT

In both cases, condylar joints fixation and fusion were done successfully.

CONCLUSION

Condylar joint stabilization and fusion may be a good or alternative option for AOD.

Association of Atlanto-Occipital Dislocation, Retroclival Hematoma, and Hydrocephalus: Management and Survival in a Pediatric Patient

Atlanto-occipital dislocation (AOD) is an injury with high morbidity and mortality. We present a case of survival of a pediatric patient with the diagnoses of AOD, retroclival hematoma, and resulting hydrocephalus. The patient's cervical spine was stabilized until occipital-cervical fusion provided definitive treatment, and the hydrocephalus was treated with a ventriculostomy. The patient survived with no neurological deficits. A better understanding and awareness of the radiologic criteria of AOD will lead to earlier recognition of AOD and improved outcomes, even in the presence of complications from AOD. Surgical fixation should be used for definitive treatment of injuries with AOD.

Traumatic atlanto-occipital dislocation in children-a case-based update on clinical characteristics, management and outcome

BACKGROUND

Atlanto-occipital dislocation (AOD) is a rare but severe sequela of high energy trauma. Children are at increased risk, due to their immature spine and biomechanical characteristics.

LITERATURE REVIEW

The prevailing mechanism of injury is motor vehicle collision as passenger. AOD commonly presents with cardiorespiratory arrest, spinal cord injury or cranial nerve deficits. Concomitant injuries, such as traumatic brain injury, are frequently encountered. Diagnosis is made on CT and MRI imaging. Posterior internal fixation is the recommended treatment. Thirty-four percent of patients die, 41 % survive with deficits and 25 % have a complete neurological recovery. Initial symptoms, GCS score and degree of spinal cord injury appear to be predictors of outcome.

ILLUSTRATIVE CASE

We report the case of a 9-year-old boy, who presented in extremis with cardiac arrest after a motor vehicle collision. Upon successful resuscitation, diagnostic imaging showed AOD and a Chiari I malformation. An occiput-C2 posterior instrumented fusion was performed. The patient subsequently received intensive rehabilitation and recovered to independent ambulation, with a persistent, asymptomatic Chiari I malformation.

CONCLUSION

This case highlights the potential for positive outcome in paediatric AOD, despite the presence of strong predictors of poor or fatal outcome at presentation.

The craniocervical junction: embryology, anatomy, biomechanics and imaging in blunt trauma

Imaging of the blunt traumatic injuries to the craniocervical junction can be challenging but central to improving morbidity and mortality related to such injury. The radiologist has a significant part to play in the appropriate management of patients who have suffered injury to this vital junction between the cranium and the spine. Knowledge of the embryology and normal anatomy as well as normal variant appearances avoids inappropriate investigations in these trauma patients. Osseous injury can be subtle while representing important radiological red flags for significant underlying ligamentous injury. An understanding of bony and ligamentous injury patterns can also give some idea of the biomechanics and degree of force required to inflict such trauma. This will assist greatly in predicting risk for other critical injuries related to vital neighbouring structures such as vasculature, brain stem, cranial nerves and spinal cord. The embryology and anatomy of the craniocervical junction will be outlined in this review and the relevant osseous and ligamentous injuries which can arise as a result of blunt trauma to this site described together. Appropriate secondary radiological imaging considerations related to potential complications of such trauma will also be discussed.

TEACHING POINTS

• The craniocervical junction is a distinct osseo-ligamentous entity with specific functional demands. • Understanding the embryology of the craniocervical junction may prevent erroneous radiological interpretation. • In blunt trauma, the anatomical biomechanical demands of the ligaments warrant consideration. • Dedicated MRI sequences can provide accurate evaluation of ligamentous integrity and injury. • Injury of the craniocervical junction carries risk of blunt traumatic cerebrovascular injury.

Pediatric occipitocervical fixation: radiographic criteria, surgical technique, and clinical outcomes based on experience of a single surgeon

OBJECTIVE If left untreated, occipitocervical (OC) instability may lead to serious neurological injury or death. Open internal fixation is often necessary to protect the neurovascular elements. This study reviews the etiologies for pediatric OC instability, analyzes the radiographic criteria for surgical intervention, discusses surgical fixation techniques, and evaluates long-term postoperative outcomes based on a single surgeon's experience. METHODS The charts of all patients < 18 years old who underwent internal OC fixation conducted by the senior author were retrospectively reviewed. Forty consecutive patients were identified for analysis. Patient demographic data, OC junction pathology, radiological diagnostic tools, surgical indications, and outcomes are reported. RESULTS The study population consisted of 20 boys and 20 girls, with a mean age of 7.3 years. Trauma (45% [n = 18]) was the most common cause of instability, followed by congenital etiologies (37.5% [n = 15]). The condyle-C1 interval had a diagnostic sensitivity of 100% for atlantooccipital dislocation. The median number of fixated segments was 5 (occiput-C4). Structural bone grafts were used in all patients. Postsurgical neurological improvement was seen in 88.2% (15/17) of patients with chronic myelopathy and in 25% (1/4) of patients with acute myelopathy. Preoperatively, 42.5% (17/40) of patients were neurologically intact and remained unchanged at last follow-up, 42.5% (17/40) had neurological improvement, 12.5% (5/40) remained unchanged, and 2.5% (1/40) deteriorated. All patients had successful fusion at 1-year follow-up. The complication rate was 7.5% (3/40), including 1 case of vertebral artery injury. CONCLUSIONS Occipitocervical fixation is safe in children and provides immediate immobilization, with excellent survival and arthrodesis rates. Of the radiographic tools evaluated, the condyle-C1 interval was the most predictive of atlantooccipital dislocation.

Occipitocervical dissociation-incidence, evaluation, and treatment

Traumatic occipitocervical dissociation (OCD) results from ligamentous injury to the craniocervical junction and is associated with a high rate of mortality and significant neurologic morbidity. The diagnosis is frequently missed on initial lateral cervical spinal radiographs mainly due to inadequate visualization of radiological landmarks and low degree of suspicion. Widespread availability of multidetector computed tomography (MDCT) of the spine and development of better diagnostic radiological criteria has allowed timely diagnosis and good clinical outcome following posterior occipitocervical fusion and instrumentation for a pathology that was once considered uniformly fatal. The present paper reviews the clinical features, diagnosis, and management of OCD in light of most recent literature.

The Application of the Revised Condyle-C1 Interval Method to Diagnose Traumatic Atlanto-occipital Dissociation in Adults

STUDY DESIGN

Retrospective study.

OBJECTIVE

Traumatic atlanto-occipital dissociation (AOD) remains a diagnostic challenge, and delay in diagnosis is associated with catastrophic outcomes. Recently, a revised version of the condyl-C1 interval (CCI) utilizing parasagittal computed tomography (CT) reconstruction was used successfully with unilateral dislocation of 2.5 mm at the level of that joint diagnostic of AOD. We report the utility of this simple technique in the diagnosis of six patients with AOD.

METHODS

Two blinded neurosurgeons assessed CTs of six patients with AOD and 30 patients without AOD. The following methodologies were applied: basion-dens interval (BDI), basion-axial interval (BAI), Lee X-lines, Powers ratio, CCI, and revised CCI. The average sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) as well as the kappa statistic indicating interrater reliability of each method were investigated.

RESULTS

The average sensitivity for BDI, BAI, Lee X-lines, Power ratio, CCI, and revised CCI was 0.75, 0.33, 0.67, 0.50, 1.00, and 1.00, respectively. The average specificity was 1.00, 1.00, 0.50, 1.00, 0.94, and 1.00, respectively. The average PPV was 1.00, 1.00, 0.25, 1.00, 0.80, and 1.00, respectively. The average NPV was 0.96, 0.88, 0.89, 0.91, 1.00, and 1.00, respectively, and the kappa statistic was 0.57, 0.25, 0.25, 0.20, 1.00, and 1.00, respectively.

CONCLUSION

Based on this study, the revised CCI method is simple yet the most sensitive and reliable technique for the diagnosis of AOD.

C1 fractures: a review of diagnoses, management options, and outcomes

The atlas is subject to fracture under axial load, often due to traumatic injuries such as shallow dives and automobile accidents. These fractures account for 2-13 % of injuries to the cervical spine [Marcon RM et al. Clinics (Sao Paulo) 68(11):1455-61, 2013]. Fractures of the C1 vertebra are often difficult to diagnose, as there is often no neurological deficit or easily identifiable findings on radiographs. However, injuries to the atlas can be associated with vertebral artery injury and atlantoaxial or atlanto-occipital instability, making prompt and accurate diagnosis imperative. A detailed understanding of the anatomy, inherent stability, and common injury patterns is essential for any surgeon treating spinal trauma. This chapter explores the diagnosis and management of C1 fractures, as well as outcomes after treatment.

Normal Development and Measurements of the Occipital Condyle-C1 Interval in Children and Young Adults

BACKGROUND AND PURPOSE

Widening of the occipital condyle-C1 interval is the most specific and sensitive means of detecting atlanto-occipital dislocation. Recent studies attempting to define normal measurements of the condyle-C1 interval in children have varied substantially. This study was performed to test the null hypothesis that condyle-C1 interval morphology and joint measurements do not change as a function of age.

MATERIALS AND METHODS

Imaging review of subjects undergoing CT of the upper cervical spine for reasons unrelated to trauma or developmental abnormality was performed. Four equidistant measurements were obtained for each bilateral condyle-C1 interval on sagittal and coronal images. The cohort was divided into 7 age groups to calculate the mean, SD, and 95% CIs for the average condyle-C1 interval in both planes. The prevalence of a medial occipital condyle notch was calculated.

RESULTS

Two hundred forty-eight joints were measured in 124 subjects with an age range of 2 days to 22 years. The condyle-C1 interval varies substantially by age. Average coronal measurements are larger and more variable than sagittal measurements. The medial occipital condyle notch is most prevalent from 1 to 12 years and is uncommon in older adolescents and young adults.

CONCLUSIONS

The condyle-C1 interval increases during the first several years of life, is largest in the 2- to 4-year age range, and then decreases through late childhood and adolescence. A single threshold value to detect atlanto-occipital dissociation may not be sensitive and specific for all age groups. Application of this normative data to documented cases of atlanto-occipital injury is needed to determine clinical utility.

Allograft versus autograft for pediatric posterior cervical and occipito-cervical fusion: a systematic review of factors affecting fusion rates

OBJECT Fusion rates are high for children undergoing posterior cervical fusion (PCF) and occipito-cervical fusion (OCF). Autologous bone has been widely used as the graft material of choice, despite the risk of donor-site morbidity associated with harvesting the bone, possibly because very low fusion rates were reported with posterior allograft cervical fusions in children several decades ago. Higher overall fusion rates using allograft in adults, associated with improvements in internal fixation techniques and the availability of osteoinductive substances such as bone morphogenetic protein (BMP), have led to heightened enthusiasm for the use of bank bone during pediatric PCF. A systematic review was performed to study factors associated with successful bone fusion, including the type of bone graft used. METHODS The authors performed a comprehensive PubMed search of English-language articles pertaining to PCF and OCF in patients less than 18 years old. Of the 561 abstracts selected, 148 articles were reviewed, resulting in 60 articles that had sufficient detail to be included in the analysis. A meta-regression analysis was performed to determine if and how age, fusion technique, levels fused, fusion substrate, BMP use, postoperative bracing, and radiographic fusion criteria were related to the pooled prevalence estimates. A systematic review of the literature was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. RESULTS A total of 604 patients met the specific inclusion and exclusion criteria. The overall fusion rate was 93%, with a mean age of 9.3 years and mean follow-up of 38.7 months. A total of 539 patients had fusion with autograft (94% fusion rate) and 65 patients with allograft (80% fusion rate). Multivariate meta-regression analysis showed that higher fusion rates were associated with OCF compared with fusions that excluded the occiput (p < 0.001), with the use of autograft instead of allograft (p < 0.001), and with the use of CT to define fusion instead of plain radiography alone. The type of internal fixation, the use of BMP, patient age, and the duration of follow-up were not found to be associated with fusion rates in the multivariate analysis. CONCLUSIONS Fusion rates for PCF are high, with higher rates of fusion seen when autograft is used as the bone substrate and when the occiput is included in the fusion construct. Further study of the use of allograft as a viable alternative to autograft bone fusion is warranted because limited data are available regarding the use of allograft in combination with more rigid internal fixation techniques and osteoinductive substances, both of which may enhance fusion rates with allograft.

Application of Normative Occipital Condyle-C1 Interval Measurements to Detect Atlanto-Occipital Injury in Children

BACKGROUND AND PURPOSE

Prior studies have found that widening or asymmetry of the occipital condyle-C1 interval on CT is a sensitive and specific marker for atlanto-occipital dislocation. Previously reported abnormal occipital condyle-C1 interval values are not age-specific, possibly leading to false-positive findings in younger children, in whom this joint space is normally larger than that in adults. This study assesses the utility of applying age-specific normative occipital condyle-C1 interval ranges to documented cases of atlanto-occipital injury compared with previously reported abnormal cutoff values.

MATERIALS AND METHODS

Retrospective review of CT and MR imaging of 14 subjects with atlanto-occipital injury was performed, and occipital condyle-C1 interval measurements were made for each subject. Sensitivities and specificities of proposed occipital condyle-C1 interval cutoffs of 2 and 3 SDs above the mean and previously published occipital condyle-C1 interval cutoffs for atlanto-occipital injury were then calculated on the basis of occipital condyle-C1 interval measurements for each subject.

RESULTS

An occipital condyle-C1 interval 2 SDs above the age-specific mean has a sensitivity of 50% and specificity of 89%-100%, depending on the age group. An occipital condyle-C1 interval 3 SDs above the age-specific mean has a sensitivity of 50% and a specificity of 95%-100%. A 4.0-mm occipital condyle-C1 interval has a sensitivity of 36% and a specificity of 100% in all age groups. A 2.5-mm occipital condyle-C1 interval has a sensitivity of 93% and a specificity of 18%-100%.

CONCLUSIONS

Occipital condyle-C1 interval widening cutoffs used to establish atlanto-occipital injury lack both sensitivity and specificity in children and young teenagers. MR imaging is necessary to establish a diagnosis of atlanto-occipital injury in children and young teenagers when the appropriate mechanism of injury is present.

Computed tomography parameters for atlantooccipital dislocation in adult patients: the occipital condyle-C1 interval

OBJECT

Atlantooccipital dislocation (AOD) in adults cannot be diagnosed with adequate specificity and sensitivity using only CT or plain radiography, and the spine literature offers no guidelines. In children, the most sensitive and specific radiographic measurement for the diagnosis of AOD is the CT-based occipital condyle-C1 interval (CCI). The goal of the current study was to identify the normal CCI in healthy adults and compare it with the CCI in adults with AOD to establish a highly sensitive and specific cutoff value for the neuroimaging diagnosis of AOD.

METHODS

A total of 81 patients, 59 without AOD and 22 with AOD, were included in this study. Measurements obtained from thin-slice CT scans of the craniovertebral joint to assess atlantooccipital dislocation included the CCI, condylar sum, the Wholey and Harris intervals, Powers and Sun ratios, Wackenheim line, and Lee X-lines.

RESULTS

The group of patients without AOD included 30 men (50.8%) and 29 women (49.2%) with a mean age of 42.4 ± 16 years (range 19-87 years). The group of patients with AOD included 10 men (45.5%) and 12 women (54.5%) with a mean age of 38.2 ± 9.7 years (range 20-56 years). Interrater reliabilities within a 95% CI were all greater than 0.98 for CCI measurements. A total of 1296 measurements of the CCI were made in 81 patients. The mean CCI for non-AOD patients was 0.89 ± 0.12 mm, the single largest CCI measurement was 1.4 mm, and the largest mean for either right or left CCI was 1.2 mm. The mean condylar sum was 1.8 ± 0.2 mm, and the largest condylar sum value was 2.2 mm. Linear regression with age predicted an increase in CCI of 0.001 mm/year (p < 0.05). The mean CCI in AOD patients was 3.35 ± 0.18 mm (range 1.5 mm-6.4 mm). The shortest single CCI measurements in the AOD patients were 1.1 mm and 1.2 mm. The mean condylar sum for all 22 AOD patients was 6.7 ± 2.7 mm and the shortest condylar sums were 3.0 mm. Cutoff values for AOD were set at 1.5 mm for the CCI and 3.0 mm for the condylar sum, both with a sensitivity of 1 and false-negative rate of 0. Sensitivity for the Powers, Wholey, Harris, Sun, Wackenheim, and Lee criteria were determined to be 0.55, 0.46, 0.27, 0.23, 0.41, and 0.41, respectively.

CONCLUSIONS

The CCI is shorter in adult patients as opposed to the pediatric population. The revised CCI (1.5 mm) and condylar sum (3.0 mm) cutoff values have the highest sensitivity and specificity for the diagnosis of AOD in the adult population.

Traumatic atlantooccipital dislocation: comprehensive assessment of mortality, neurologic improvement, and patient-reported outcomes at a Level 1 trauma center over 15 years

BACKGROUND CONTEXT

Only Level 3 evidence exists for the diagnosis and treatment of atlantooccipital dislocation (AOD) with few studies examining mortality, neurologic improvement, and patient-reported outcomes (PROs).

PURPOSE

First, the aim was to determine: the incidence of AOD, 90-day surgical morbidity and mortality after AOD, patient factors that may be associated with delayed or missed diagnosis, and factors that were associated with mortality and neurologic improvement after AOD. Secondly, the aim was to quantify the pain, disability, and quality of life experienced by patients surviving AOD.

STUDY DESIGN/SETTING

This was a retrospective cohort study.

PATIENT SAMPLE

A total of 5,337 consecutive spine computed tomography traumagrams from 1997 to 2012 were included.

OUTCOME MEASURES

Mortality, neurologic improvement, complications, EuroQol five dimensions (EQ-5D), Neck Disability Index (NDI), Numeric Rating Scale (NRS)-neck, NRS-arm, and return-to-work were the outcome measures.

METHODS

Patients were considered to have AOD if they met one of the following radiographic criteria: basion-dens interval greater than 10 mm; basion-axial interval: anterior displacement greater than 12 mm or posterior displacement greater than 4 mm between the basion and posterior C2 line; and condyle to C1 interval greater than 1.4 mm. Linear regression analysis was performed to identify factors associated with 90-day mortality, neurologic improvement, and missed diagnosis. Patient-reported outcomes were assessed via phone interview.

RESULTS

Thirty-one patients met radiographic criteria for AOD; an incidence of 0.6% over 15 years. Twenty-one (68%) patients were treated with occipital cervical fusion. At 90 days postoperatively, there were no new neurologic deficits or reoperations. Eight (26%) patients died within 90 days. All patients who died had no documented AOD diagnosis and were not treated surgically. Missed AOD diagnosis was the strongest predictor of mortality. Younger age, lower Glasgow Coma Score, lower Injury Severity Score (ISS) score, and worse initial American Spinal Injury Association (ASIA) score were significantly associated with greater neurologic improvement. Higher ISS score and better ASIA score were significantly associated with missed AOD diagnosis. The average PROs metrics at time of telephone follow-up were as follows: EQ-5D=0.73±0.19, NDI=30.89±18.57, NRS-neck=2.33±2.21, NRS-arm=2.00±2.54. Of the patients with follow-up data, four were employed full-time, and five were receiving disability.

CONCLUSIONS

Our work suggests that failure to diagnose AOD is a powerful predictor of mortality. Higher ISS scores and better neurologic presentation were significantly associated with missed diagnosis. Craniocervical arthrodesis preserved neurologic function with low complication rate and unexpectedly high PROs and return-to-work. These results must be carefully interpreted because it is unclear whether missed AOD diagnosis accompanies another death-causing injury (eg, traumatic brain injury) or if failure to treat AOD contributes to mortality in a multifactorial manner.

In vitro biomechanics of the craniocervical junction-a sequential sectioning of its stabilizing structures

BACKGROUND CONTEXT

Occipitocervical dislocations involve translations of the craniocervical joints. The relative contributions of each ligament to overall stability and the effects of the occipitoatlantal joint capsules on the pathologic translation are unknown. Although incidences of occipitocervical dislocations are rare after blunt trauma, they are usually fatal. When patients do survive these dislocations, the proper diagnosis is difficult, which in turn may increase the fatality rate. A biomechanical model may provide a greater pathologic understanding of craniocervical subluxation.

PURPOSE

The purpose of the study is to build an in vitro biomechanical model to determine which stabilizing ligament(s) of the craniocervical junction are most important in restraining rotation and translations during these rotations. This may guide clinical diagnosis, which could assist in treatment options.

STUDY DESIGN/SETTING

The study design includes a biomechanical cadaveric test.

METHODS

Seven cadaveric specimens were tested using a 6-degree-of-freedom spine simulator under the following conditions: intact, clivus/alar removal (CR), transverse ligament destruction (TLD), occipitoatlantal (OA) joint capsulotomyoccipitoatlantal (OA) joint capsulotomy (C0-C1 JC), and C1-C2 joint capsulotomy (C1-C2 JC). Flexion-extension (FE), lateral bending (LB), and axial rotation (AR) were applied (2.5 Nm) to a C0-C2 segment, whereas anterior-posterior (AP) and cranial-caudal (CC) translations were recorded. Average motions were normalized to intact (100%) for each joint.

RESULTS

Increases in C0-C1 angular and translational motions occurred after TLD and C0-C1 JC. At the atlantoaxial joint, there were significant (p<.05) increases from intact in FE (TLD=154%, C0-C1 JC=174%) and in AR (TLD=178%, C0-C1 JC=224%). Anterior-posterior translation during applied LB increased significantly after TLD (248% intact). Cranial-caudal translation during applied FE increased significantly after TLD (188%) and C0-C1 JC (361%). Increases in C1-C2 angular motion occurred after TLD and C1-C2 JC and in translation after CR and TLD. At the C1-C2 joint, there were significant increases from intact in FE (TLD=172%, C1-C2 JC=160%) and in LB (TLD=286%, C1-C2 JC=332%); in AR, there were no statistical differences. Anterior-posterior translation increased significantly after CR (280%). Cranial-caudal translation also increased significantly after CR (205%) and TLD (298%) during LB.

CONCLUSIONS

Transverse and alar ligaments appear to be the main stabilizers of the craniocervical junction. The vertical structures attached to the clivus and OA joint capsules function as secondary stabilizers. Craniocervical dislocations seem to affect FE and lateral bending the most, whereas increased translation seems to occur primarily in the AP and CC directions. Models of craniocervical trauma should section all three restraining structures for the future studies.

Early Identification of Traumatic Durotomy Associated with Atlantooccipital Dislocation May Prevent Retropharyngeal Pseudomeningocele Development

Atlantooccipital dislocation can be complicated by a traumatic durotomy that may lead to the rare development of a retropharyngeal pseudomeningocele. To our knowledge this has been reported only five times previously. We present the case of a 60-year-old man involved in a motor vehicle accident who suffered an atlantooccipital dislocation and C5-C6 three-column injury. A unique MRI image of a defect in the ventral dura posterior to C2 was appreciated. He underwent occiput to T2 internal fixation and arthrodesis. During surgery, CSF egress was seen caudal to the right C2 nerve root. A DuraMatrix onlay patch reinforced with DuraSeal was placed to stop the CSF leak. A lumbar subarachnoid drain was also placed. The patient made a satisfactory recovery with residual mild weakness of his right upper extremity. In this report, we demonstrate that careful MRI review can reveal a ventral durotomy in a traumatic atlantooccipital dislocation and, if discovered, effective treatment including a lumbar subarachnoid drain for CSF diversion may prevent progression to a retropharyngeal pseudomeningocele. The literature on this rare presentation and associated durotomy is provided.

Blunt cerebrovascular injuries in association with craniocervical distraction injuries: a retrospective review of consecutive cases

BACKGROUND CONTEXT

Blunt cerebrovascular injuries (BCVIs) have the potential to cause brain, cerebellar, and/or spinal cord ischemia. Certain subtypes of spine fractures, such as vertebral subluxation, fractures through the foramen transversarium, and C1-C3 fractures have been linked to a higher incidence of BCVI. On the other hand, BCVI in association with craniocervical distraction injuries (CCDs) have been only anecdotally reported.

PURPOSE

We hypothesized that because CCD is also caused by a high-energy hyperflexion/hyperextension distraction mechanism, it could also be associated with a high incidence of BCVI.

STUDY DESIGN/SETTING

Retrospective chart review.

PATIENT SAMPLE

Of 46 consecutive patients with unstable craniocervical dissociations treated operatively at a single Level I trauma center from January 1996 to December 2009, 29 of the 46 had vascular studies that comprised the study sample.

OUTCOME MEASURES

Primary outcomes assessed were BCVI subdivided into blunt carotid artery injuries and/or blunt vertebral artery injuries and classified according to the Biffl criteria. Secondary measures included associated strokes and evidence of emboli on transcranial Doppler.

METHODS

All consecutive patients diagnosed with unstable CCD injuries that were surgically treated at a single Level I trauma center during the period of 1996 to 2009 were identified. Those who were adequately screened with a catheter angiogram and/or computed tomography angiogram of the neck so as to rule out BCVI were included in this study. Electronic medical records were used to determine mechanism, demographics, clinical findings, and transcranial Doppler reports. Angiography and computed tomography angiograms were analyzed to assess for BCVI. If a BCVI was identified, these were classified using the Biffl criteria.

RESULTS

Among the 29 screened patients, 30 BCVIs were identified in 15 patients. According to the Biffl criteria, there were 13 Grade I, eight Grade II, five Grade III, three Grade IV, and one Grade V injuries. Three major strokes were diagnosed in those 15 patients with BCVI, as opposed to none among the other 14 patients without BCVI.

CONCLUSIONS

Blunt cerebrovascular injuries were seen in more than 50% of the patients screened, with major strokes occurring in 20% of the patients. We suggest screening for BCVI in all patients presenting with C0-C1 and/or C1-C2 distraction injuries.