[Upper cervical spine injuries and their diagnostic features]

The upper cervical spine includes the articulations of the occiput with atlas and the atlas with the axis, as well as the bony structures of the base of the skull, axis, and atlas. The unique anatomy of the upper cervical spine and the typical mechanisms of injury yield a predictable variety of injury patterns. Injuries to this area include occipital condyle fractures, occipitoatlantal dislocations, subluxations and dislocations of the atlantoaxial articulation, atlas fractures, odontoid fractures, and fractures of the arch of the axis. Injuries to this region are relatively common and can be easily overlooked because patients with the upper cervical injury may have an associated head injury, which can alter their level of consciousness and complicate obtaining an accurate history and physical examination. The complex regional anatomy and overlying structures make plain radiographic images difficult to interpret. Delayed recognition can result in significant disability. A thorough understanding of the clinical presentation, radiographic assessment, and mechanisms of injury can minimize morbidity and enhance treatment effectiveness for the more common upper cervical ligamentous and bony injuries.