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

Abstract

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.

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

“…The current recommendation for diagnosis is to measure the condyle-C1 interval (CCI) using a CT scan in the coronal plane and more recently in the sagittal plane [ 2 - 4 ]. This method has been proven to provide the diagnosis with very high sensitivities and positive predictive values approaching 100%.…”

“…A value of 2.5 mm is diagnostic of this injury. There are other methods that have been used to diagnose AOD including basion-dens interval (BDI), basion-axial interval (BAI), X-lines of Lee, Powers ratio, with variable sensitivities [ 2 ]. We report a case of a patient who suffered a motor vehicle accident and had concomitant AOD and atlanto-axial dislocation.…”

The atlanto-occipital joint: a concise review of its anatomy and injury

“…[14] The intraarticular fluid sign is shown by the magnetic resonance imaging (MRI) and indicates a disrupted AOJ capsule and an injury to the surrounding ligaments. [15] The revised OC to C1 interval (CCI) shown by the computed tomography (CT) is highly sensitive and specific for an atlanto-occipital injury and is measured from the bottom of the OC to the deepest point in the valley of the SAS of C1 in the parasagittal plane. [15] A CCI of greater than 2.5 mm is considered diagnostic of unilateral or bilateral AOJ dislocation.…”

“…[15] The revised OC to C1 interval (CCI) shown by the computed tomography (CT) is highly sensitive and specific for an atlanto-occipital injury and is measured from the bottom of the OC to the deepest point in the valley of the SAS of C1 in the parasagittal plane. [15] A CCI of greater than 2.5 mm is considered diagnostic of unilateral or bilateral AOJ dislocation. [15] A fracture of the OC is relatively rare and two classification systems are utilized.…”

“…[15] A CCI of greater than 2.5 mm is considered diagnostic of unilateral or bilateral AOJ dislocation. [15] A fracture of the OC is relatively rare and two classification systems are utilized. Anderson and Montesano developed three categories of OC fractures: type Iimpaction fracture of the OC, which is considered stable, type II -fracture of the skull base in which the fracture line crosses the OC, type III -avulsion fracture of the OC resulting in ligamentous instability.…”