|
CT Scan Chiari malformation requires non-ionic iodine myelography and cisternography CT scan or delayed scan, combined with sagittal reconstruction images, showing the following changes:
|
|---|
| I type: Symmetrical crescent or rectangular low-density shadow behind the cervical spinal cord, which is the herniated cerebellar tonsil. |
| II type: In addition to the manifestations of type I, the skull, dura mater, brain parenchyma, ventricles, and cisterns may have the following changes: ① Multiple skull depressions appear in the frontal, parietal, and occipital bone plates within 6 months of infants. More than half of the patients have a flattened or flattened posterior border of the petrous bone, and the internal auditory canal is shortened. The older the age, the more significant the changes. The falx cerebri line-like enhancement becomes thinner and is dysplastic, and the line-like enhancement interruption is perforated. The low position of the tentorium cerebelli makes the posterior cranial fossa narrow, the tentorial notch widens, and the tentorial notch elongates. ② The intercollicular sulcus of the quadrigeminal plate disappears. The colliculi fuse, and the beak-like deformed midbrain extends posteriorly and inferiorly between the cerebellar hemispheres. The lateral part of the cerebellum surrounding the brainstem forms a "three-peak" image with the cerebellopontine angle cistern and the ventral side of the pons. ③ The fourth ventricle is small or not visible, the third ventricle and lateral ventricles are enlarged, and the coronal plane shows a notch on the outer edge of the anterior horn, forming a "3" shape with the concave shape of the third ventricle. The cisterna magna disappears. |
|
MRI More accurate, clear, and intuitive than CT images, can directly confirm the diagnosis. The imaging findings are as follows:
|
| I type: ① The cerebellar tonsil is deformed and displaced, tongue-shaped, herniated more than 5mm below the foramen magnum into the upper cervical spinal canal; ② The cisterna magna is reduced, and may be combined with craniovertebral junction malformations; ③ May be combined with hydrocephalus and syringomyelia, each accounting for 20%~25%. |
| II type: ① The cerebellar elongated tongue-shaped protrusion can move to the C2-4 level or below through the atlas, the cerebellum is dysplastic and extends caudally, herniated through the foramen magnum to the upper edge of the C1 vertebral arch, and the foramen magnum is significantly enlarged; ② The brainstem is significantly elongated, and the medulla oblongata herniates into the cervical spinal canal; ③ The cervical spinal cord moves downward, the upper cervical nerve roots relatively rise to the exit level, and the cerebellum and fourth ventricle herniate into the spinal canal; ④ The tentorium cerebelli is dysplastic, and the low position of the tentorium cerebelli also causes the position of the straight sinus, transverse sinus, and confluence of sinuses to move downward; ⑤ May be combined with various complex malformations, such as myelomeningocele, hydrocephalus, as well as syringomyelia, brain malformations, basilar invagination, and spinal cord splitting malformations. |
| III type: In addition to the manifestations of type II, there is obvious basilar invagination, cervical vertebral malformation, enlarged foramen magnum, and meningoencephalocele in the low occipital or high cervical region. |
| IV type: Severe cerebellar hypoplasia, no displacement, enlarged fourth ventricle, widened posterior cranial fossa cisterns, and brain sulci. |
Home
Back
