Prenatal diagnosis of chiari type 1 malformation

Although Chiari type 1 malformation is common in the pediatric setting, no prenatal case has been reported.

To present a case of Chiari 1 malformation diagnosed prenatally based on both imaging and biological findings and describe the clinical and postnatal imaging follow-up.

A 33-year-old woman was referred for a prenatal diagnosis of Chiari 2 malformation based on second trimester routine prenatal ultrasound. Neurosonogram depicted an abnormal posterior fossa including poor identification of the cerebellum borders with decrease of both infra- and supra-tentorial peri-cerebral spaces but without any evidence of spinal dysraphism. These features were consistent with normal alpha-fetoprotein and acetylcholinesterase levels. Fetal magnetic resonance imaging (MRI) at 24 gestational weeks confirmed sonographic data showing cerebellar tonsils ptosis below the foramen magnum associated with normal position of both fourth ventricle and vermis without any associated spinal anomalies. Postnatal MRI confirmed the prenatal diagnosis of Chiari type 1 malformation. Both clinical and imaging at 48-month follow-up demonstrated normal development without any clinical symptoms related to the Chiari type 1 malformation nor any other pathological features.

Although prenatal diagnosis of Chiari type 1 malformation has not yet been reported, this condition can be detected on both prenatal biological and imaging features. Postnatal natural evolution of this prenatal diagnosed condition can be benign when Chiari type 1 malformation is isolated, as suggested by our case.