Hospital: Hospital San Juan de la Cruz.
Aut@r o Autores: E. Perez Cuenca, E. Garcia Sancho, M. Moral Molero.
We report the case of a 73-years-old woman who was taken to Emergency Room due to recurrent syncopes. A head CT was requested in order to rule out intracranial patology. In head scanner it was detected the fusion between C1 vertebrae and the base of the skull, and ascent of the odontoid process that stenosed the formamen magnum and was in contact with medullar cord. Subsequently the study was completed with CT and MRI of the cervical spine. Sagital reconstructions revealed increased anterior atlanto-dens interval measuring 7 mm suggestive of atlantoaxial subluxation. In addition the odontoid process of the axis was located above the Chamberlain and McRae lines what is related in basilar invagination, despite this no signs of myelopathy were detected in MRI
The diagnoses was complete atlantooccipital assimilation Key learning points: - Congenital fusion between the atlas and the base of the occiput. It can be partial o complete - May lead to chronic atlantoaxial inestability and basilar invagination - The incidence has been reported to be from 0.008 to 3% - Usually asymptomatic but when symptons are present they can be serious caused by neural or vascular compression - Conventional x-ray imaging is ussually difficult to interpret, for this reason CT and MRI are mandatory to confirm the diagnose to demostrate functional stability and detect complications that may require surgital treatment
The atlanto-occipital assimilation consists of the congenital fusion of the first cervical vertebra (atlas) to the base of the skull due to a failure of the segmentation process. Atlas assimilation may include alteration of the atlantooccipital articulation or narrowing of the spinal canal. Most of the abnormalities cause no typical symptom, but some patients show neurological problems with correlate with radiological findings. The knowledge of this variation may be of importance to orthopedic surgeons, neurosurgeons and radiologist.
- Ciolkowski MK, Krajewski P, Ciszek B. A case of atlas assimilation: description of bonny and soft structures. Surg Radiol Anat 2014, 36:833-836 - Kim KR, Lee YM, Kim YZ, Cho YW, Kim JS. Cervical Myelopathy secondary to atlanto-occipital assimilation: t