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Anterior Fontanelle Dermoid
Joseph Junewick, MD FACR
over 10 years ago
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Atlanto-axial Dissociation and Cervical Hyperextension

Case Detail

Anatomy: Brain-Spine
Joseph Junewick, MD FACR
Diagnostic Category: Trauma
Created: over 11 years ago
Updated: over 11 years ago
Tags: PEDS
Modality/Study Types: CT MR
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3 year old male restrained backseat passenger involved in high-speed head-on-collision now unresponsive.

Case Images


Atlanto-axial Dissociation and Hyperextension Injury at C6-C7 with Cervical Cord Disruption


CT – Widened predental space with abnormal basion-axial and basion-dental intervals. Note the normal synchondrosis of the anterior arch of C1 and the normal appearance of the lower cervical spine.

MR – Sagittal T, FS T1, IR, and FSE2 and axial FSE2 demonstrate 1) precervical edema/hemorrhage, 2) suboccipital edema, 3) edema and hemorrhage at the basion-dental interval, 4) fracture of the anterior-inferior endplate at C6,5) disrupted anterior longitudinal ligament, 6) redundant posterior longitudinal ligament, 7) extensive prevertebral edema, and 8) partial cord disruption.


Atlanto-axial: Atlanto-axial dislocation is usually the result of a longitudinal distraction force. Various ligamentous support is disrupted, including the transverse atlanto-axial ligaments.

Hyperextension: A blow to the face or forehead results in hyperextension of the posterior elements. The posterior column acts as a fulcrum which leads to distraction of the anterior column and disruption of the anterior longitudinal ligament. The force is carried through the disc or the inferior endplate. The posterior longitudinal ligament and posterior elements may fail if the force is sufficient. If both anterior and posterior longitudinal ligaments fail, there is transient anterior translation of the upper vertebra leading to anterior and posterior injury of the cord.


Harris JH and Mirvis SE. The Radiology of Acute Cervical Spine Trauma, 3rd Ed (1996).

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