A rare case of atlantooccipital dissociation in the context of occipitalization of the atlas, with a 2-year follow-up: case report

Upper Cervical Trauma

Craniocervical injuries (CCJs) account for 10% to 30% of all cervical spine trauma. An increasing number of patients are surviving these injuries due to advancements in automobile technology, resuscitation techniques, and diagnostic modalities. The leading injury mechanisms are motor vehicle crashes, falls from height, and sports-related events. Current treatment with urgent rigid posterior fixation of the occiput to the cervical spine has resulted in a substantial reduction in management delays expedites treatment of CCJ injuries. Within CCJ injuries, there is a spectrum of instability, ranging from isolated nondisplaced occipital condyle fractures treated nonoperatively to highly unstable injuries with severely distracted craniocervical dissociation. Despite the evolution of understanding and improvement in the management of cases regarding catastrophic failure to diagnose, subsequent neurologic deterioration still occurs even in experienced trauma centers. The purpose of this article is to review the injuries that occur at the CCJ with the accompanying anatomy, presentation, imaging, classification, management, and outcomes.

A report of two cases of familial occipitalization of the atlas in a father and his daughter

Occipitalization of the atlas (OA) (atlantooccipital assimilation) is a rare congenital anomaly that results in fusion of the C0-C1 complex. Here, we report the two cases of familial OA occurring in a father and his daughter and describe the pathologic features of this rare developmental anomaly. A 70-year-old father and his 30-year-old daughter seeking conservative care for musculoskeletal complaints presented to a chiropractic clinic. Radiographs of the cervical spine demonstrated OA. This represents a novel example of this anomaly in two patients with a direct familial relationship.

Successful non-operative management for atlanto-occipital dislocation resulting in spinal cord contusion in a patient with atlanto-occipital assimilation and severe Chiari I malformation

Background:

Atlanto-occipital dislocation (AOD) is a rare, highly morbid, and highly lethal injury that results from high-energy trauma and almost universally requires operative management for satisfactory outcomes. It can be difficult to identify the severity of injury at the time of presentation, and when diagnosis is delayed outcomes worsen significantly. Anatomic anomalies of the craniovertebral junction may further complicate its detection. When such anomalies are present either singly or in combination, they are known to cause space constraints which may increase the likelihood of spinal cord injury. Given that such anomalies and AOD are rare, few examples of patients with both are reported in the literature. Furthermore, it is not clear in what way patient management may be impacted in this context.

Case Description:

We will present a unique case of an 18-year-old patient with traumatic AOD and an intact neurologic examination who was found to have atlanto-occipital assimilation (AOA), platybasia, basilar invagination, and severe Chiari I malformation, who was treated effectively with non-operative management.

Conclusion:

Our case demonstrates the successful application of a non-operative treatment strategy in a carefully selected patient with AOD in the context of AOA.

Traumatic Atlanto-occipital Dislocation: Analysis of 15 Survival Cases With Emphasis on Associated Upper Cervical Spine Injuries

STUDY DESIGN

Retrospective case analyses.

OBJECTIVE

The aim of this study was to investigate the incidence and characteristics of associated upper cervical spine injuries in 15 survival cases of traumatic atlanto-occipital dislocation (AOD).

SUMMARY OF BACKGROUND DATA

Traumatic AOD is a rare and generally fatal injury. Information regarding associated upper cervical spine injuries that may affect treatment methods, outcomes, and prognosis is limited.

METHODS

Fifteen patients (11 patients with posterior-type AOD and four patients with vertical-type AOD) who survived traumatic AOD were included in this study. Plain radiographs, computed tomography, magnetic resonance imaging, and medical records were reviewed. The incidence and characteristics of associated upper and lower cervical spine and thoracolumbar spine injuries and brain injuries were evaluated.

RESULTS

Thirteen patients with traumatic AOD (11 patients with posterior-type AOD and two patients with vertical-type AOD) showed associated upper cervical spine injuries; the overall incidence was 87% (100% in posterior-type AOD and 50% in vertical-type AOD). In posterior-type AOD, eight (72.7%) patients had C1 fractures (four patients had three-part fracture, three patients had two-part fracture, and one patient had four-part fracture), four (36.4%) patients had C1 lateral mass fractures, two (18.2%) patients had transverse atlantal ligament injuries. In vertical-type AOD, two (50%) patients had C1-C2 vertical subluxation with C1 anterior arch horizontal and sagittal split fractures. In posterior-type AOD, two (18%) patients had lower cervical spine injuries and one (9%) patient had brain injury. In vertical-type AOD, one (25%) patient had thoracic spine injury, and three (75%) patients had brain injuries additionally.

CONCLUSION

Survival cases with traumatic AOD showed a high incidence of associated upper cervical spine injuries and brain injuries. High index of suspicion and careful radiologic examination are needed to investigate the presence of associated upper cervical spine injuries and brain injuries in traumatic AOD, which affects treatment, outcome, and prognosis.

LEVEL OF EVIDENCE

4.

Traumatic posterior atlantooccipital dislocation with Jefferson and occipital condyle fractures: A case report

RATIONALE

To the best of our knowledge, this is the first report on a case of a traumatic posterior atlantooccipital dislocation (AOD) with 3-part Jefferson and occipital condyle fractures.

PATIENT CONCERNS

We report the case of a 60-year-old male with posterior AOD with 3-part Jefferson fracture and fracture of right occipital condyle. This injury occurred as a result of rolling down from a mountain. The patient complained of severe neck pain showing bony tenderness and ecchymosis in the high cervical area but did not show any neurologic abnormalities.

DIAGNOSES

Reconstructed computed tomography scans clearly demonstrated a 3-part Jefferson fracture and fracture of right occipital condyle, and posteriorly displaced occiput with respect to the anterior arch of C1 and dens of C2.

INTERVENTION

We planned to perform occipitocervical fusion; however, the patient refused treatment. He was transferred to another hospital and lost to follow-up.

OUTCOMES

Although extremely rare, patient who had posterior AOD with 3-part Jefferson and occipital condyle fractures can survive without neurological compromise, as was observed in our patient.

LESSONS

Clinical suspicion with thorough radiographic and physical examinations are very important for diagnosing of the upper cervical spine injuries such as AOD with Jefferson and occipital condyle fractures.

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.

Clival Screw Placement in Patient with atlas assimilation: A CT-based feasibility study

Clival screw and plate fixation technique is an alternative or supplement to the occipitocervical instrumentation. However, no report has clarified the applied anatomy of clivus in patients with atlas assimilation (C1A), especially for clival screw fixation. Therefore, we measured the parameters of clival lengths, widths, putative screw lengths, clival-cervical angel and foramen magnum diameters on CT images in a cohort of 81 C1A patients and patients without C1A. The clivus showed a rectangular shape in 96.3% (78/81) of C1A patients, and a normal-like triangle shape in 3.7% (3/81) of C1A patients. The intracranial clival length decreased 13% (37 mm) in C1A patients, the extracranial clival length 14.8% (24.1 mm), the clival-cervical angle 6.2% (122.3°) and the superior screw length 11.3% (14.1 mm), the sagittal diameter of foramen magnum 16% (28.0 mm), respectively. There was no significant difference in the widest or narrowest clival width, or the middle screw length, or the transverse diameter of foramen magnum between groups. The inferior clivus was feasible for an average 9.7-mm-length screw placement in C1A patients, while not in patients without C1A. The present study characterizes clivus of C1A patients with an unnormal-like rectangular shape, and confirmes a screw placement at the inferior clivus.

Feasibility of C2 Vertebra Screws Placement in Patient With Occipitalization of Atlas: A Tomographic Study

Occipitalization of atlas (OA) is a congenital disease with the possibility of anomalous bony anatomies and the C2 pedicle screw insertion is technically challenging. However, there are no existing literatures clarified the dimensions and angulations of the C2 pedicles, lamina and lateral masses for screw insertion in patients with OA. Therefore, the aim of this study was to assess the morphometric features of C2 for screw placement in OA to guide the use of surgical screws. Measurements of the OA patients on the computer tomography (CT) images including lamina angle, length and thickness, pedicle angle, length and thickness, and lateral mass thickness and length of the axis vertebra. The OA patients data were compared with age and gender matched cohort of randomly selected patients in a control group without OA. The picture archiving and communication system was used for all patients who had received cervical CT scanning between January 2001 and January 2015. Measurements were performed independently by 2 experienced observers who reviewed the CT scans and recorded the patients with OA. Statistical analysis was performed at a level of significance P < 0.05. A total of 73 patients (29 males and 44 females) were eligible to be included in the OA group. In most of the measurements the pathological cohort had significantly smaller values compared to the control group (P < 0.05). In the OA group, only 45% of the pedicles and 88% of the lamina had thicknesses bigger than 3.5 mm. Both groups had all pedicle and lamina lengths bigger than 12 mm. Regarding the length of the lateral mass, no value was bigger than 12 mm in the OA group, whereas 40% of the values in the control group were bigger than 12 mm. The average pedicle and laminar angles were 37° and 49° in the patients with OA, respectively. The variable anatomy in patients with OA needs to be taken into account when performing spinal stabilization as the C2 bony architectures are significantly smaller than normal. Anatomically, translaminar screw is a more viable option in comparison with pedicle screw for C2 fixation in OA. Nevertheless, the suitability should be fully assessed prior to surgery.