To explore the prenatal ultrasound features of fetal unilateral cerebellar hypoplasia.

The prenatal ultrasonograms of six fetuses at Shenzhen Maternity and Child Healthcare Hospital Affiliated to Nanfang Medical University, who were diagnosed as having unilateral cerebellar hypoplasia were retrospectively reviewed. The prenatal ultrasound characteristics were summarized, and compared with the features of magnetic resonance imaging (MRI), postnatal ultrasound, and autopsy examinations. A literature review of prenatal diagnosis of such abnormality was performed.

The prenatal ultrasonograms of the six cases of unilateral cerebellar hypoplasia were characterized as asymmetry of the cerebellar hemispheres and/or a decrease in the transverse cerebellar diameter, with or without deformity of the cerebellar vermis. The cerebellum volume of the affected side decreased, along with an abnormal morphology, while the contralateral side was normal. Three cases had irregular borders in the affected side. After birth, one of the six fetuses was followed to one year old without neurological symptoms. Based on the prenatal and postnatal examination results of the six cases in the present study and those of 36 cases reported in the literature, it was found that cases with isolated unilateral cerebellar hypoplasia and those without intracranial abnormalities or other adverse pregnancy history like prenatal growth restriction or premature birth had better short-term prognosis than unilateral cerebellar hypoplasia fetuses with intracranial abnormalities.

Unilateral cerebellar hypoplasia can be prenatally diagnosed based on the characteristic ultrasonic features and MRI can be used for differential diagnosis.