ventriculomegaly

Ventriculomegaly is defined by dilation of one or more cerebral ventricles (lateral, third, or fourth) and is classified based on atrial width measured on prenatal ultrasound or postnatal imaging: mild (10-12 mm), moderate (12-15 mm), and severe (>15 mm). It differs from hydrocephalus in that hydrocephalus implies increased intracranial pressure due to CSF outflow obstruction or overproduction, whereas ventriculomegaly is a descriptive term that may or may not involve elevated pressure.

Etiologies include: (1) obstructive causes such as aqueductal stenosis, Chiari malformation, or Dandy-Walker malformation; (2) destructive/atrophic processes from intraventricular hemorrhage, periventricular leukomalacia, or congenital infections (TORCH, especially CMV and toxoplasmosis); (3) genetic syndromes (trisomy 21, 18, 13); and (4) idiopathic/isolated cases, which often have a good prognosis if mild and non-progressive.

Clinical workup includes detailed anatomic ultrasound to rule out associated anomalies, fetal MRI for further characterization, TORCH titers, and karyotype/microarray testing given the association with aneuploidy. Isolated mild ventriculomegaly generally has a favorable prognosis (~90% normal outcome), while moderate-severe or ventriculomegaly with additional anomalies carries higher risk of neurodevelopmental delay, cerebral palsy, and need for postnatal neurosurgical intervention (e.g., ventriculoperitoneal shunting).

Postnatally, ventriculomegaly may present with macrocephaly, bulging fontanelle, sunset eyes, developmental delay, or signs of increased intracranial pressure if hydrocephalus is present. Management depends on the underlying cause and whether CSF diversion procedures are indicated.