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Proposed Grading System for Posterior Atlantooccipital Membrane Complex Injuries on Cervical Magnetic Resonance
Peter Fiester1, Gazanfar Rahmathulla1, Dalys Haymes1
1Department of Neuroradiology, University of Florida College of Medicine, Jacksonville, Florida, USA.
Background:
The posterior atlantooccipital membrane complex consists of the posterior atlantooccipital membrane and posterior atlantoaxial membrane. Posttraumatic, posterior atlantooccipital membrane complex injuries may have varied appearances on cervical magnetic resonance imaging. The purpose of this study was to identify the different types of posterior atlantooccipital membrane complex injuries that occur in trauma patients.
Methods:
Patients who suffered a posterior atlantooccipital membrane complex injury were identified retrospectively using key word searches of cervical magnetic resonance imaging reports between 2013 and 2020 using Nuance mPower software. All relevant imaging studies were reviewed by 2 neuroradiologists. A description of the location and type of posterior atlantooccipital membrane complex injury was recorded, along with additional osteoligamentous trauma of the craniocervical junction and relevant clinical history.
Results:
Forty-one patients were identified with acute posterior atlantooccipital membrane complex injury. Four distinct patterns of posterior atlantooccipital membrane complex injury were observed.
Conclusions:
A grading system for posterior atlantooccipital membrane complex injuries is proposed on the basis of these data: grade 1-edema confined to the posterior atlantooccipital and atlantoaxial membrane; grade 2-edema confined to the posterior atlantooccipital and atlantoaxial membrane and ligamentum nuchae; grade 3-stripping injury of the posterior atlantooccipital membrane with C1-C2 dorsal epidural hematoma; and grade 4-frank disruption of the posterior atlantooccipital membrane at C1 with edema in the remaining posterior atlantooccipital membrane complex.
