This case demonstrates the typical finding of a kinked fetal brainstem, associated with severe ventriculomegaly and a dysplastic cerebellar vermis.
The differential for this constellation of findings includes:
- L1-CAM mutation (X-linked aqueduct stenosis)
a-dystroglycanopathies (Walker-Warburg syndrome, muscle-eye-brain disease).
Genetic testing in this patient had shown L1-CAM mutation. Although the diagnosis cannot be made with certainty on imaging alone, relevant negatives in this case (which might have favoured one of the other differential diagnoses) include:
- non-enlarged ganglionic eminences
- no evidence of lissencephaly or polymicrogyria (though even when present, this may be difficult to detect prenatally particularly in the setting marked ventricular distension)
- absence of globe abnormalities.
No relevant family history was available in this case, but this should be looked for (FDIU or intellectual disability in a male child of either the patient or a first degree female relative).