Chiari II malformation

Case contributed by Assoc Prof Frank Gaillard


Neurological impairment since birth.

Patient Data

Age: 25 years
Gender: Male

Right parieto-occipital VP shunt in situ. The right lateral ventricle is slit-like with mild prominence of the temporal horn. The left lateral ventricle is dilated, particularly the trigone. No subdural collection. Diffuse abnormal sulcation throughout the occipital and parietal lobes with polygyria but no focal cortical thickening or signal abnormality and no loss of normal grey-white matter interface. The mantle of tissue lying anterior to the temporal horns is reduced in thickness bilaterally.

Callosal dysgenesis with shortened AP diameter and focal thinning of the anterior body. The inferior colliculi of the tectal plates are prominent and the posterior cranial fossa is small with extensive tonsilar herniation again noted and resulting in crowding of the foramen Magnum. The pineal recess of the third ventricle is prominent, presumably related to callosal dysgenesis, however pineal cyst is difficult to entirely exclude on the images provided.

The cervical cord is somewhat flattened in its AP diameter throughout but shows no focal compression or signal abnormality. Abnormal tissue extending posterior to the upper cervical cord to the C2/3 disc level, more to the left than right, is due to very elongated tonsillar herniation. A few prominent flow voids are also noted adjacent, however there is no evidence of vascular malformation.

There are only four non-rib bearing lumbar type vertebra demonstrated. Alignment is anatomical. No suspicious osseous lesion. No definite posterior element fusion abnormality is demonstrated, in keeping with the known repaired spina bifida lying within the lower sacral region.

Tethered cord, terminating at L4/S1 level. Short segment focal dilatation of the central canal of the cord at the L3/4 disc level. Cord signal is otherwise unremarkable.

Case Discussion

This patient was born with a sacral myelomeningocoele which was reparied in the neonatal period. Tethered cord and cerebral abnormalities are all in keeping with a Chiari II malformation. Hydrocephalus, a common complication, is also present and has required shunting. 

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