Prenatal or neonatal forebrain anomaly, suspected holoprosencephaly
Recommended: Prenatal Ultrasound + Fetal MRI (or postnatal MRI Brain) is the preferred imaging study for prenatal or neonatal forebrain anomaly, suspected holoprosencephaly. Failed cleavage of prosencephalon.
Recommended study
Prenatal Ultrasound + Fetal MRI (or postnatal MRI Brain)
Failed cleavage of prosencephalon. Spectrum from alobar (severe) to lobar (mild).
If the default doesn't apply
Postnatal characterization
MRI
MRI Brain with thin-section coronal
No contrast
Watch-outs
Midline craniofacial anomalies
Cyclopia / proboscis with alobar; cleft lip/palate with semilobar. Genetic testing (trisomy 13, SHH pathway).
Endocrine dysfunction
Posterior pituitary often absent or ectopic — screen for DI / hypopituitarism in survivors.
Pearls
- Alobar: monoventricle + fused thalami + no falx, callosum.
- Semilobar: partial separation of hemispheres posteriorly.
- Lobar: minor abnormality, only absent septum pellucidum and frontal lobe fusion.