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Pseudosubluxation

Case contributed by Jeremy Jones
Diagnosis certain

Presentation

Fall from monkey bars. High cervical tenderness, but no neurology.

Patient Data

Age: 7 years
Gender: Male
x-ray

The normal distance between the C1 and C2 spinous processes should measure less than 12 mm. However, this measurement can be effected by a degree of magnification and is therefore of limited use.

This patient does have a relative increase in the C1/C2 spinous process distance, but there is not other abnormality of alignment or evidence of fracture. 

No prevertebral soft tissue swelling.

mri

Normal alignment of the cervical spine. No abnormal high-signal in the upper cervical vertebra bodies and no evidence of ligamentous injury.

Case Discussion

In children, the occiput is relatively large compared to the rest of the head. This means that when a child lies flat, the cervical spine is not in the neutral position, but partially flexed. This can result in pseudosubluxation and increase in the posterior interspinous distance even when there is no associated ligamentous injury.

Pediatric patients are much more likely to have ligamentous rather than osseous spinal injury and while a limited CT through the craniocervical junction could be performed, an MRI will give more soft tissue information and exclude ligamentous injury.  If there is concern for fracture, a limited CT could be performed subsequently.

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