Atlanto-occipital Dislocation Research Articles

Effects of the adjustive tractor in treatment of cervical dislocation

Objective To observe the clinical effects of the adjustive tractor for cervical dislocation.Methods Forty-seven patients were included between September 2007 and November 2011.There were 36 males and 11 females with age ranged from 7 to 62 (mean,35 years).The mean interval from injury to admission was 8.6 h (range,0.5-72 h).There were atlanto-occipital dislocation in 2 cases,C1.2 in 2 cases,C2.3 dislocation in 5 cases,C3.4 dislocation in 2,C4.5 in 9,C5.6 in 13,C6.7 in 14.Thirty cases were complicated by fracture.No facet locking occurred in sixteen cases.Facet locking was found in ten cases and bilateral facet locking was in 21 cases.After reduction,brace or internal fixation followed.According to American Spinal Injury Association (ASIA) spinal function impairment scale standard,there were 4 cases in level A,10 cases in level B,18 in C,10 in D,and 5 in E.According to Japanese Orthopaedic Association (JOA) spinal function rating standard,the mean JOA score was 9 (range,2-14).Results All 47 cases were reduced successfully without neuronal function aggravation.Traction power ranged from 7 to 60 kg (mean,25.6 kg),the mean time of traction was 8 min (range,3-10 min).The mean follow-up was 38 (range,6-48) months.All the patients achieved normal alignment and intervertebral height.The intervertebral body fusion was observed in all of cases,the mean fusion time was 3.3 months (range,3-6 months).One patient who experienced nonunion of vertebral arch fracture didn't receive further treatment because of absence of symptoms.At last follow-up,there were 3 cases in level A,1 in level B,4 in C,8 in D,and 31 in E according to ASIA scale.The mean JOA score was 12 (range,2-17).Conclusion The adjustive tractor is simple and safe for prompt reduction. Key words: Cervical vertebrae; Dislocations; Fractures; Traction

Surgical Strategies in Craniovertebral Junction Lesions

Objective: Outcome analysis of surgical management in craniovertebral junction (CVJ) lesions (trauma, congenital anomalies [CA], and rheumatoid arthritis [RA]). Methods: Sixty-three patients with CVJ pathology underwent surgery between 1998 and 2011. Trauma occurred in 49 cases, CA in 3, and RA in 11. Diagnostics consisted of neuro-orthopedic status assessment and neuroimaging. Patients were divided into two groups according to dominating clinical syndromes (DCSs): Group I was neurologically complicated with spinal cord compression, group 2 was orthopedically complicated with unstable injuries and high risk of secondary neuro-orthopedic lesions. Results: Group I (24 patients) with spinal cord compression had absolute indications for surgery, including myelopathic syndrome. These patients underwent single, two-stage surgery including spinal cord decompression and fixation. The first stage was decompression. The decompression target was chosen by compression direction as follows: Anterior decompression was done in cases with anterior compression (transoral-transpharyngeal approach), posterior decompression was done in cases with posterior compression. Group II (39 patients) had unstable injuries with high risk of secondary neuro-orthopedic lesions. The fixation method was chosen differentially. In cases of acute dental fracture, cannulated fixation was used; for atlanto-occipital dislocation, craniocervical fixation was used; for transarticular C1-C2, in case of Hangman's fracture, ACDF C2-C3 was used. Eighty-two percent of patients had follow-up from 1 year up to 5 years. We achieved positive outcome in 94.3% of patients. Three of 63 patients after surgery (4.6%) had complications. Conclusion: Spinal cord compression is an absolute indication for surgery. Wide bone resection requires safe internal fixation. Surgery in patients with instability without myelopathic manifestations provides possibilities for better functional outcomes in a shorter time.

Appearance of a Rapidly Expanding Facial Eschar in a Severely Injured Trauma Patient

A 21-YEAR-OLD WOMAN PRESENTS TO THE TRAUMA RESUSCITATION UNIT VIA helicopter transport following a motor vehicle crash. She was an unrestrained driver involved in a front-end collision and had a prolonged extrication from the vehicle. At the scene, she was unresponsive and underwent emergency intubation. She sustained multiple severe traumatic injuries including a ruptured spleen requiring abdominal exploration and splenectomy, atlantooccipital dislocation requiring halo placement, bilateral pelvic fractures requiring pelvic binder, and left lower extremity crush injury with multiple open fractures ultimately requiring a left hemipelvectomy. She underwent 38 operative interventions in a 3-week period. The plastic surgery department is consulted 14 days after the initial crash to evaluate a 4 4-cm left cheek wound measuring 2.5 cm deep with exposed zygomaticus major muscle (FIGURE 1A). In the ensuing 48 hours, the wound rapidly progresses and develops a necrotic eschar (Figure 1B). What Would You Do Next?

Traumatic Atlanto-occipital Dislocation (AOD).

ObjectiveTraumatic atlanto-occipital dislocation (AOD) results from high energy trauma and is an uncommon and usually fatal injury due to an injury to the cervicomedullary junction. Recently, improved prehospital management, early diagnosis and effective treatment led to increasing reports of survival. This study of patients with AOD initial imaging modalities recognizes the clinical features and diagnostic considerations for a quick diagnosis.MethodsIn this article, five survived adult patients with traumatic AOD are presented and retrospectively reviewed. Diagnosis was made by lateral cervical spine x-ray, cervical computed tomography (CT), or magnetic resonance imaging(MRI). Treatment consisted of early immobilization, respiratory support, and subsequent occipitocervical fusion.ResultsFour patients were male and the other one was female. Three were diagnosed early and the others were delayed in confirmations. One was type I AOD and four were type II AOD. All patients were applied occipitocervical fusion. Two cases were worse; neurological states and the other three that showed no change. Lateral X-ray film of all patients in the prevertebral soft tissue swelling at the C2 level was noted. The mean thickness of prevertebral soft tissue C2 level was 17.88 mm(15.18 to 20.17mm). Two were in the normal range of dens-basion index(DBI), three showed abnormalities, and Power's ratio was abnormal in 3 patients.ConclusionAs for damages caused by a strong external force in patients with severe prevertebral soft tissue swelling at C2 level abnormaly, the doctor determines whether more should be carefully AOD and considers 3D CT or MRI to confirm AOD in these patients.

Occipital condyle fractures. Prospective follow-up of 31 cases within 5 years at a level 1 trauma centre

Prospective investigation of incidence and outcome of occipital condyle fractures (OCF) in a level 1 trauma centre. Over a period of 5 years, we prospectively recorded all cases of OCF, and performed a 1-year post-injury radiological and clinical follow-up using CT imaging, SF-36 and Neck Disability Index, respectively. A total of 31 patients with OCF were identified. Based on a total of 2,616 CT scans that had been performed during this period, the incidence was 1.19%. There were 27 unilateral and 4 bilateral OCFs. Furthermore, 3 out of 31 patients (9.7%) were additionally diagnosed with atlanto-occipital dislocation (AOD), one of which was dorsally stabilised in a surgical procedure. All other patients were treated conservatively. 5 out of 31 patients (16.1%) died due to the severity of associated injuries. 22 out of 31 patients (70.9%) were prospectively followed-up for 1 year after trauma. During this period, CT imaging showed bony consolidation of fractures in all cases except for one, with no evidence of secondary dislocation or nonunion. Evaluation of the Neck Disability Index showed moderate disability. The SF-36 questionnaire showed an impaired quality of life in all areas; however, these were determined by associated injuries and independent of the type of fracture. Both unilateral and bilateral OCFs represent a stable injury regardless of the type of fracture. If AOD has been diagnosed in addition, it requires surgical stabilisation-independent of the OCF-and it is a significant predictor for poor outcomes. The patients quality of life 1 year after trauma has not been affected by the OCF, but by the overall pattern of the injury and by comorbidities. Based on our results, we introduce a new, simple and practical classification for OCFs.

Survivor of a traumatic atlanto-occipital dislocation

Atlanto-occipital dislocation is a devastating ligamentous injury that most often turns fatal. However, because of on-site resuscitation improvements, the emergency teams are increasingly dealing with this condition. We report a rare case of atlanto-occipital dislocation (AOD) in a surviving patient with more than one-year follow-up. The mechanism of injury appears to be an extreme hyperextension applied to the head. This injury occurs more frequently in children since they are anatomically predisposed (flat articulation between the occiput and the atlas, increased ligamentous laxity). The diagnosis should be suggested by severe neurological injury after high trauma but also post-traumatic cardiorespiratory deficit. There have been reports of atlanto-occipital dilocations without neurologic impairment. A radiographic examination must be performed and lateral cervical radiographs should be acquired. However, additional imaging with CT or MRI may be required to aid diagnosis of AOD in cases in which radiographic findings are equivocal. Once the diagnosis of AOD has been confirmed, an anatomical classification should be made according to the magnitude of displacement. Fatal lesions are of neurological and vascular origin and some authors advocate the systematic use of angiography. Consensus regarding the management of AOD in adults has been achieved. Occipito-cervical arthrodesis is the recommended treatment option. We advocate a two-stage surgery: the patient is initially fitted with a halo vest then occipitocervical fusion is performed. Surgical treatment should be combined with cardiorespiratory management. The emergency teams should get familiar with this injury since they will be increasingly confronted to it. Early recognition and standard appropriate management is essential to avoid delayed treatment and complications.

Traumatic retroclival epidural hematoma in pediatric patient--Case report and review of literature

Background:Retroclival epidural hematoma (REDH) is a very rare entity in the practical field of neurosurgery. Only a few cases have been reported in literature. The authors present to you case of a 12-year-old female, a victim of road traffic accident (RTA), who had presented to us with loss of consciousness and seizures.Case Description:Magnetic resonance imaging revealed retroclival hematoma. She was managed on conservative grounds and discharged with assurance of multiple follow-up visits.Conclusion:Very few cases of REDH have been reported in pediatric population to date. It should be suspected in children with head and neck injuries who have been a victim of RTAs. Most likely underdiagnosed due to its rarity; therefore, MRI should be considered when the suspicion is high. Atlanto-occipital dislocation should always be kept under consideration in all cases, and therefore should be managed and monitored very cautiously. In this report, the authors also present concise review of the literature pertaining to the pathogenesis and management of this rare clinical entity which has a high likelihood to be encountered and underdiagnosed by neurosurgeons in Emergency Room.

Atlanto-Occipital Dislocation With Retroclival Hematoma in a Pediatric Patient Presenting to the Emergency Department

Atlanto-occipital dislocation is a rare, oftentimes fatal injury sustained from high-impact trauma. It is seen more often in children compared with adults. In the past decade, there are more pediatric survivors presenting to the emergency department for treatment. This case reviews the presentation, diagnosis, and treatment of a child who survived this injury.

Retroclival Epidural Hematomas

Abstract BACKGROUND Retroclival epidural hematomas (REDHs) are infrequently reported. To our knowledge, only 19 case reports exist in the literature. OBJECTIVE This study was performed to better elucidate this pathology. METHODS We prospectively collected data for all pediatric patients diagnosed with REDH from July 2006 through June 2009. Data included mechanism of injury, Glasgow Coma Scale score, neurological examination, treatment modality, and outcome. Magnetic resonance imaging was used to measure REDH dimensions. RESULTS Eight children were diagnosed with REDH, and the hematomas were secondary to motor vehicle–related trauma in all cases. The mean age of patients was 12 years (range 4–17 years). The mean REDH height (craniocaudal) was 4.0 cm, and the mean thickness (dorsoventral) was 1.0 cm. At presentation, the mean Glasgow Coma Scale score was 8 (range 3–14), and there was no correlation between hematoma size and presenting symptoms. Two patients died soon after injury, and 2 additional patients had atlanto-occipital dislocation that required surgical intervention. No patient underwent surgical evacuation of the REDH. The mean follow-up was 14 months. At most recent follow-up, 4 patients are neurologically intact, 1 patient has a complete spinal cord injury, and 1 patient has mild bilateral abducens nerve palsy. CONCLUSION To our knowledge, this study of 8 pediatric patients is the largest series of patients with REDH thus far reported. Based on our study, we found that REDH is likely to be underdiagnosed, atlanto-occipital dislocation should be considered in all cases of REDH, and many patients with REDH will have minimal long-term neurological injury.

Non-traumatic posterior atlanto-occipital joint dislocation

This report presents a case of non-traumatic posterior atlanto-occipital dislocation. A 36-year-old female was referred with a history of numbness of the extremities, vertigo and neck pain for 1year. The patient had no history of trauma. The axial rotation of range of motion of the cervical spine was severely restricted. A lateral cervical radiograph in the neutral position demonstrated a posterior atlanto-occipital dislocation. A coronal view on a computed tomography (CT) reconstruction image showed a loss of angle of the bilateral atlanto-occipital joint, and a sagittal reconstruction view of CT images also demonstrated flatness of atlanto-occipital joint. Instrumented occipito-cervical fusion was performed after reduction. A lateral cervical radiograph in the neutral position 1year after surgery showed the reduction of atlanto-occipital joint, moreover, it was maintained even in an extended position. The patient had neurologic improvement after surgery. Flatness of the bilateral atlanto-occipital joint may have induced this instability. Occipital-cervical fusion was chosen in the present case since the patient showed restricted axial rotation of the neck before surgery. The surgery improved the preoperative symptoms including the function of cervical spine evaluated by JOACMEQ.

Timely recognition of traumatic atlanto-occipital dislocation in a child based on occipital condyle–C1 interval analysis: excellent neurological recovery

A case of atlanto-occipital dislocation (AOD) is presented to illustrate the importance of subtle imaging findings and the occipital condyle-C1 interval (CCI) measurement in the evaluation of high cervical spine injury. Although AOD is commonly considered to be fatal, recently there have been an increasing number of reports of children surviving this injury. Prompt recognition and treatment of AOD are crucial for survival. The authors present a case of an 8-year-old boy who sustained a destabilizing injury without bone disruption but with ligamentous tears that rendered his cervical spine unstable from the occiput to the C-1 level. On admission, imaging findings were consistent with tectorial membrane damage, perimedullary subarachnoid hemorrhage, and extraaxial blood from the clivus to the C-2 level. Most standard cervical spine radiological indices were within normal limits except the CCI. After initial management in a cervical collar, the patient was placed in halo vest, and subsequently underwent occiput to C-3 fusion. Timely recognition of the injury and subsequent craniocervical stabilization with internal fixation resulted in full neurological recovery. This report supports CCI as a valuable index for the prompt recognition of AOD. It also supports recent literature suggesting that AOD is a survivable injury with the possibility for an excellent neurological recovery.

Intraarticular Atlantooccipital Fusion for the Treatment of Traumatic Occipitocervical Dislocation in a Child

A case report of traumatic atlantooccipital dislocation (AOD) managed by intraarticular-posterior fusion from a posterior approach at the C0-C1 level with preservation of C1-C2 motion. To present a new technique for atlantooccipital fusion with long-term follow-up. There is an increasing number of patients with AOD who have preservation of neurologic function. The most frequent method used to treat this condition is occipitocervical fusion. There has been a tendency in recent years to minimize the extent of stabilization, performing occipitoatlantal fusion only. However, it is difficult to achieve a solid fusion between C0 and C1, and the long-term effect of the insufficiency of lig. alaria on C0-C2 stability is unknown. The authors present a modified technique of C0-C1 fusion that aims to enhance fusion and achieve greater stability. A 11-year-old child with AOD was initially treated unsuccessfully with a halo device for 3 months. As instability persisted, an isolated C0-C1 fusion was performed from a posterior approach. This anatomically based intraarticular fusion technique comprises removal of the articular cartilage of the atlantooccipital joints, and cancellous bone autografting at the atlantooccipital joints and between the occiput and posterior arch of C1, supported by an occipital plate linked by rods to lateral mass screws in the atlas. This technique of increased bony fusion surface and internal fixation provided an excellent result with full recovery of minor neurologic deficits. At long-term follow-up, 9 years after surgery, the patient was free of signs and symptoms; solid fusion of the C0-C1 joint, and normal values for rotation of the C1-C2 segment were recorded. Intraarticular and posterior fusion of the atlantooccipital joint was able to provide an excellent long-term clinical outcome in the treatment of traumatic AOD in a child. This is the first report of an intraarticular fusion of the C0-C1 segment and the longest follow-up published on isolated C0-C1 stabilization.

Atlantooccipital dislocation in motor vehicle side impact, derivation of the mechanism of injury, and implications for early diagnosis

Numerous reports of atlantooccipital dislocations (AODs) have been described in frontal impacts and vehicle versus pedestrian collisions. Reports of survival after AOD in conjunction with side impacts have infrequently been reported in the literature. The objective of this study is to present a case of an AOD from a side impact vehicle collision, and deduce the mechanism of injury. A clinical and biomechanical reconstruction of the collision was performed to investigate the mechanism of the dislocation. A 51-year-old female was traveling in a four-door sedan and sustained a side impact collision with a compact pickup truck. At the time of extrication, the patient was neurologically intact with a Glasgow Coma Scale score of 15. After admittance to the hospital, the patient developed a decline in respiratory status, right mild hemiparesis, and left sixth-nerve palsy, and magnetic resonance imaging (MRI) and computed tomography (CT) reconstructions indicated a craniocervical dislocation. Surgical fixation was performed and all extra-axial hemorrhaging was evacuated. At discharge, the patient was neurologically intact on the left side, had right mild hemiparesis, left sixth-nerve palsy, and minor dysarthria. Survival rates of AODs have recently been increasing. Morbidity is still more prevalent, however. Due to the variety of symptoms that accompany AODs and the inconsistency of diagnostic imaging techniques, a thorough history of the etiology may lead to increased clinical suspicion of this injury and further raise survival rates.

Cruciate paralysis secondary to traumatic atlantooccipital dislocation

Cruciate paralysis is a clinical phenomenon thought to result from injury to decussating pyramidal tract fibers at the cervicomedullary junction, producing clinical findings of upper-extremity weakness out of proportion to the lower extremities. The authors present, to their knowledge, the first reported case of cruciate paralysis resulting from atlantooccipital dislocation.

Offene Reposition und dorsale Spondylodese C0-C2 bei atlantookzipitaler Dislokation

We report the case of a 73-year-old male patient who was suffered trauma after a syncopal fall onto a railway track in the form of an atlanto-occipital dislocation. The diagnostic revealed a bilateral fracture of the occipital condyles coupled with a ventral atlanto-occipital dislocation (Jeanneret type 4) and also an odontoid fracture (Anderson type 2). The patient underwent dorsal spondylodesis of C0-C2 in combination with Magerl's C1-C2 screw fixation. Pre-operatively and postoperatively no neurological abnormalities were found. This rarely occurring and survived traumatological situation is described using the present case as an example.

Traumatic Atlanto-Occipital Dislocation - A Case Report-

Survival after traumatic atlanto-occipital dislocation is rare. Severe persistent neurological deficits are common in the survivors, but early resuscitation and the use of the newer diagnostic techniques have contributed to improved outcomes. We present here the case of a 42 year old man with traumatic atlanto-occipital dislocation combined with a dens fracture, and the patient obtained good clinical results after we applied a Halo-vest and performed posterior fusion.

Survival After Concurrent Traumatic Dislocation of the Atlanto-Occipital and Atlanto-Axial Joints

A case report of a patient who survived a traumatic disassociation of both atlanto-occipital and atlantoaxial joints. OBJECTIVE.: To describe a rare case of concurrent atlanto-occipital and atlantoaxial dislocation with a review of the related literature regarding occipitocervical dislocation. Cases of isolated atlanto-occipital or atlantoaxial dislocation have typically resulted in death or devastating neurologic deficit. Survival after the simultaneous dislocation at both joints is extremely rare. The initial evaluation, subsequent management, and surgical treatment of a 25-year-old male who sustained a concurrent dislocation of the atlantoaxial and atlanto-occipital joints from a motor vehicle collision are reported and the related literature is discussed. The patient was transferred to our hospital after initial stabilization according to Emergency Medical Service criteria and management based on the Advanced Trauma Life Support protocol. A complete (ASIA A) spinal cord injury was diagnosed on admission. Radiographic evaluation revealed dislocations of the atlanto-occipital and atlantoaxial joints. Subsequently, the patient underwent surgical stabilization with instrumented posterior fusion from the occiput to C5. Intraoperatively, traumatic pseudomeningocele was diagnosed and repaired with pericranial autograft. The vital function parameters currently remain stable, but the patient is ventilator-dependent and did not regain motor or sensory function. The rapid response time of emergency medical services and stabilization according to the Advanced Trauma Life Support protocol now lead to the survival of patients with significant deficit from occipitocervical injuries. A high index of suspicion is required to appropriately manage a patient with this devastating injury in order to maximize the chance for survival.

Luxação traumática atlanto-occipital: relato de caso

Traumatic atlanto-occipital dislocation is a rare lesion whose incidence is not know, and which is associated to a high rate of mortality. The authors report the diagnosis, treatment, and two-year follow-up of a 25 year-old patient who had had an automobile accident with imaging-confirmed traumatic atlanto-occipital dislocation.

Analysis of Cervical Injuries in Persons With Head Injuries

To determine which clinical factors are useful for predicting concomitant injuries of the cervical spine and cervical spinal cord in persons with head injuries, we examined the nature and mechanisms of cervical injuries. For 109 forensic autopsies of persons with head injuries, the cause of injury, mechanism of cervical injury, survival time, and anatomic injury severity (1990 revision of the abbreviated injury scale [AIS] and injury severity score) were determined. Traffic accidents were the most common cause of injuries (41.3%), followed by slips and falls (24.8%), assaults (17.4%), and falls from height (9.2%). The mean maximum AIS scores and the AIS scores of the head or neck were similar in the 4 groups. Cervical spine injuries and epidural or subdural hemorrhages of the cervical spinal cord were more common in persons dying in traffic accidents and falls from height than in persons dying in slips and falls or assaults. Cervical injuries were significantly more common in persons sustaining frontal impacts than lateral or rear impacts. The most common cervical hyperextension injuries were atlanto-occipital and atlantoaxial dislocation and injuries of the 5th intervertebral disc. Our results suggest that persons with injuries of the head due to high-energy frontal impacts should be carefully examined for concomitant cervical injuries. These findings should be helpful for decreasing preventable deaths from undiagnosed cervical injuries in head-injured persons.

ATLANTO-OCCIPITAL DISLOCATION—PART 2

The diagnosis of atlanto-occipital dislocation (AOD) remains problematic as a result of a lack of reliable radiodiagnostic criteria. In Part 1 of the AOD series, we showed that the normal occiput-C1 joint in children has an extremely narrow joint gap (condyle-C1 interval [CCI]) with great left-right symmetry. In Part 2, we used a CCI of 4 mm or greater measured on reformatted computed tomographic (CT) scans as the indicator for AOD and tested the diagnostic sensitivity and specificity of CCI against published criteria. The clinical manifestation, neuroimaging findings, management, and outcome of our series of patients with AOD are also reported. For diagnostic sensitivity, we applied the CCI criterion on 16 patients who fulfilled one or more accepted radiodiagnostic criteria of AOD and who showed clinical and imaging hallmarks of the syndrome. All 16 patients had plain cervical spine x-rays, head CT scans, axial cervical spine CT scans with reconstruction, and magnetic resonance imaging scans. The diagnostic yield and false-negative rate of CCI were compared with those of four published "standard" tests, namely Wholey's dens-basion interval, Powers' ratio, Harris' basion-axis interval, and Sun's interspinous ratio. The diagnostic value of "nonstandard" indicators such as cervicomedullary deficits, tectorial membrane and other ligamentous damage, perimedullary subarachnoid hemorrhage, and extra-axial blood at C1-C2 were also assessed. For diagnostic specificity, we applied CCI and the "standard" and "nonstandard" tests on 10 patients from five classes of non-AOD upper cervical injuries. The false-positive diagnostic rates for AOD of all respective tests were documented. The CCI criterion was positive in all 16 patients with AOD with a diagnostic sensitivity of 100%. Fourteen patients had bilateral AOD with disruption and widening of both OC1 joints. Two patients had unilateral AOD with only one joint wider than 4 mm. The abnormal CCI varied from 5 to 34 mm. Eight patients showed blatant left-right joint asymmetry in either CCI or anatomic conformation. The diagnostic sensitivities for the "standard" tests are as follows: Wholey's, 50%; Powers', 37.5%; Harris', 31%; and Sun's, 25%, with false-negative rates of 50, 62.5, 69, and 75%, respectively. The sensitivities for the "nonstandard" indicators are: tectorial membrane damage, 71%; perimedullary blood, 63%; and C1-C2 extra-axial blood, 75%, with false-negative rates of 29, 37, and 25%, respectively. Fifteen patients with AOD had occiput-cervical fusion. There were one early and two delayed deaths (19% mortality); two patients (12%) had complete or severe residual high quadriplegia, but 11 children (69%) enjoyed excellent neurological recovery. CCI was normal in all 10 patients with non-AOD upper cervical injuries with a diagnostic specificity of 100%. The false-positive rates for the four "standard" tests were: Sun's, 60%; Harris', 50%; Wholey's, 30%; and Powers', 10%; for the "nonstandard" indicator, the rates were: cervicomedullary deficits, 70%; tectorial membrane damage, 40%; C1-C2 extra-axial blood, 40%; and perimedullary blood, 30%. The CCI criterion has the highest diagnostic sensitivity and specificity for AOD among all other radiodiagnostic criteria and indicators. CCI is easily computed from reconstructed CT scans, has almost no logistical or technical distortions, can capture occiput-C1 joint dislocation in all three planes, and is unaffected by congenital anomalies or maturation changes of adjacent structures. Because CCI is the only test that directly measures the integrity of the actual joint injured in AOD and a widened CCI cannot be concealed by postinjury changes in the head and neck relationship, it surpasses others that use changeable landmarks.