Review Question - QID 214149

The tectorial membrane is noted by the line labeled "C" in Figure B.

The tectorial membrane ligament connects the posterior body of the axis to the anterior foramen magnum and is the cephalad continuation of the posterior longitudinal ligament. The tectorial membrane contributes to the stability of the atlanto-occipital joint. An atlanto-occipital dislocation (AOD) is generally caused by high-energy trauma leading to translation or distraction of the occipitocervical junction. MRI studies are the gold standard for diagnoses of these injuries although radiographs and CT cervical spine can also be used to diagnose AOD in the event of a disrupted powers ratio (Illustration B). Treatment of an AOD generally involves prompt surgical management.

Astur et al. review the diagnosis and management of AOD injuries in children. They note that MRI is the preferred imaging modality for diagnosis while occasionally, flexion/extension/distraction fluoroscopy may be required to determine craniovertebral stability. They note that early surgical stabilization is recommended for all children and comprises of occipitocervical fusion. They note that halo immobilization and traction are contraindicated in the management of AOD in children because of the risk of displacement of the injured occipitocervical joint.

Glaun and Phillips review three cases of AOD in three siblings involved in a single, head-on, motor vehicle accident. They noted that the oldest sibling (9-year-old girl) required surgical fixation, the second sibling (6-year-old boy) was treated nonsurgically with a brace and the youngest sibling, a 5-year-old boy, sustained a fatal AOD. They noted that the proposed CT measuring techniques for the diagnosis of AOD were inconsistent in the 3 cases. The authors conclude that in the setting of clinically suspected AOD with normal CT measurements, cervical spine MRI is necessary to properly assess the extent of ligamentous injury.

Figure A is the sagittal T2-weighted MRI of the cervical spine which shows a large disc-osteophyte complex at C3-C4. Figure B is the same MRI image with arrows pointing at A (posterior atlanto-occipital membrane), B (posterior longitudinal ligament), C (the tectorial membrane), D (alar ligament), and E (anterior longitudinal ligament). Illustration A is a labeled version of Figure B. Illustration B shows the power's ratio measurement.

Incorrect Answers:
Answer 1: Line A is the posterior atlanto-occipital membrane.
Answer 2: Line B is the posterior longitudinal ligament.
Answer 4: Line D is the alar ligament.
Answer 5: Line E is the anterior longitudinal ligament.