Microcephaly

Case contributed by Stacy Goergen
Diagnosis certain

Presentation

Reduced fetal cranial biometry

Patient Data

Age: Progressive, multiple studies
Gender: Female

23w6d

mri

There is delay of cerebral sulcation for gestational age. There is underdeveloped Sylvian operculisation. The parieto-occipital and calcarine sulci are not seen and would be expected at this stage, particularly in as there is no evidence of ventricular enlargement to account for their absence. In addition, the normal zonal anatomy of the cerebral hemispheres is difficult to identify and this does not appear to be due to motion degradation.

Frontooccipital cerebral hemispheric measurement is below the lower limit of the normal range.

The corpus callosum is present. No abnormality of the cerebellum, brainstem or orbits. No evidence of intraventricular hemorrhage.

Importantly, there is a normal appearance of the ganglionic eminences, which would typiically be enlarged in conditions producing lissencephaly, such as LIS1 gene mutation, dystroglycanopathies, tubulinopathies and mutations of the RELN and ARX genes.

MRI followup was recommended at this stage, to determine whether there was a persistent lag of sulcal development. 

Amniocentesis:  Normal microarray and negative CMV PCR.  
Negative TORCH screen.

27w0d

mri

Biometry:

31w 5d

mri

Biometry:

Postnatal clinical progress:  At 6 weeks postnatal the baby’s head circumference was below the first centile for age, and she was failing to fix and follow on visual testing.

6 weeks postnatal

mri

Subtle finding of a simplified gyral pattern. Review the image comparing this case to an age matched normal brain: gyri are present but shallower than normal.  The cortex is not thickened and the brain otherwise structurally normal.

Persistent hyperplastic primary vitreous is noted bilaterally, with retinal detachment also suspected on the left. This was not detectable on the prenatal MRI, even in retrospect.

PHPV was confirmed at opthalmologic review and patient underwent a vitrectomy. Adequate development was noted at the 4 month pediatric review.

Case Discussion

Microcephaly with a simplified gyral pattern. This imaging series demonstrates delayed but progressive cerebral development. Small head size became evident progressively on pre-natal imaging, and the head circumference <3SD postnatally confirms the diagnosis of microcephaly. 

There were no associated cerebral abnormalities in this case, however microcephaly may be associated with cortical malformations, dysgenesis of corpus callosum and dysplasia or hypoplasia of the brainstem and cerebellum.

Interestingly, the associated bilateral persistent hyperplastic primary vitreous was only evident on the post-natal MRI.

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