Radiological Category Musculoskeletal Principal Modality 1 Conventional Radiograph

Radiological Category: Musculoskeletal Principal Modality (1): Conventional Radiograph Principal Modality (2): CT Case Report #0176 Submitted by: Virginia Scroggins, M. D. Faculty reviewer: Ron Bilow, M. D Date accepted: 10 February, 2005 This case report presented at the 87 th annual meeting of the Radiological Society of North America, 28 November 2004, Abstract reference # 0032 MK-CE-e.

Case History Eight-year-old female in motor vehicle collision. The patient was intubated at the scene.

Radiological Presentations

Radiological Presentations

Test Your Diagnosis Which one of the following is your choice for the appropriate diagnosis? After your selection, go to next page. • Jefferson burst fracture • Anterior subluxation • Occipitoatlantal subluxation • Atlanto-axial dislocation

Findings and Differentials Findings: Single lateral radiograph of the cervical spine demonstrates widening of the atlantodental interval. The patient in intubated, obscuring the prevertebral soft tissue contour. Axial CT again shows widening of the atlanto-dental interval and narrowing of the central spinal canal. Differentials: • Atlanto-axial subluxation • Occipitoatlantal subluxation • Jefferson Burst Fracture

Discussion The normal anterior atlantodental interval (AADI) on a neutral lateral radiograph is <3 mm in adults and <5 mm in children. Abnormal widening of the AADI in a trauma patient indicates injury to the transverse atlantal ligament. Mechanism include hyperflexion, lateral tilt or vertical compression. Nontraumatic causes of AADI widening include inflammatory arthritides (RA, AS, psoriatic, Reiters, SLE), Down’s syndrome and retropharyngeal abscess. Widening of the AADI

Discussion Sagittal T 1 MR image demonstrates increased signal within the cervical cord representing edema from cord contusion 3 -D image demonstrates the injury resulting in spinal canal narrowing (click on image to repeat)

Discussion In occipitoatlantal subluxation, there is separation of the occipital condyle from the lateral masses of C 1. This is diagnosed on lateral radiographs as an increase in the basion-dental interval greater than 12. 5 mm. A Jefferson burst fracture is a vertical compression injury in which the axial load is transmitted from the vertex to the occipital condyles to the lateral masses of C 1. The classic Jefferson injury involves fractures of the anterior and posterior arches of C 1. This injury is best illustrated on open-mouth odontoid views with lateral displacement of the lateral masses of C 1. On lateral views of the cervical spine, usually only the posterior arch fractures of C 1 can be seen with abnormal prevertebral soft tissue contour.

Diagnosis Atlanto-axial subluxation. References: Harris JH Jr. Harris WH. The Radiology of Emergency Medicine, 4 th ed. Philadelphia: Lippincott Williams & Wilkins, 2000: 235 -257.