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Type:
Educational Exhibit
Keywords:
Congenital, Diagnostic procedure, MR, CT, Neuroradiology spine
Authors:
O. Nessej, C. Drissi, M. Mahmoud, K. Walha, N. Hammami, R. Sebaï, S. Nagi, M. Ben Hamouda; Tunis/TN
DOI:
10.1594/ecr2015/C-1510
Background
The CCJ is a complex region of the axial skeleton located between the skull-base and the upper cervical spine,
along with its neural components [1].
Its stability is mainly based on strong complex ligamentous and bony structures that are also responsible for the majority of axial rotation (at the atlantoaxial complex) and flexion-extension movements (at the occiput-C1 joint) [2].
Congenital abnormalities of the CCJ include bony anomalies and Chiari malformations.
Chiari malformations are a heterogeneous group of abnormalities grouped under a common heading because they were initially described by the same Austrian pathologist H.
Chiari,
in two papers published at the end of the nineteenth century (Chiari 1891,
1896).
The Chiari malformations comprise the common types I and II,
the rare type III,
and a fourth type whose definition and autonomous dignity is still debated among authors [3].
Although all these entities share common features,
such as a variable degree of reduction in size of the posterior fossa and (with the exception of the type IV) herniation of portions of the cerebellum into the foramen magnum,
it is accepted that type I (resulting from a mesodermal hindbrain abnormality) should be separated from the other types that are related to neural tube closure defects [5].
We individualize two large groups of bony anomalies of the CCJ: the major malformations which can have neurological impact such as the basilar invagination,
and the minor malformations that don’t have a neurological impact but they are important to know because they can lend confusion with other anomalies including traumatic.
The surgical management of congenital craniovertebral anomalies is complex due to the relative difficulty in accessing the region,
critical relationships of neurovascular structures and the intricate biomechanical issues involved.
Improved imaging has provided an opportunity to clearly observe the bony abnormality.
Dynamic MRI and CT scan have helped in the evaluation of these anomalies,
in the assessment of the biomechanics of the joints and in the formulation of a rational surgical strategy [4].