Which is the most common cause of ventriculomegaly in newborn?
**Core Concept**
Ventriculomegaly in newborns refers to an enlargement of the cerebral ventricles, which can be caused by various factors. The most common cause is related to the obstruction of cerebrospinal fluid (CSF) pathways, leading to an accumulation of CSF within the ventricles.
**Why the Correct Answer is Right**
The most common cause of ventriculomegaly in newborns is the Dandy-Walker malformation, which involves a congenital defect in the development of the cerebellum and the fourth ventricle. This defect leads to a partial or complete obstruction of the fourth ventricle, resulting in an accumulation of CSF and subsequent ventriculomegaly. The Dandy-Walker malformation is often associated with other congenital anomalies, such as hydrocephalus, and can be diagnosed prenatally or postnatally through imaging studies like ultrasound or MRI.
**Why Each Wrong Option is Incorrect**
**Option A:** Congenital hydrocephalus is a possible cause of ventriculomegaly, but it is not the most common cause in newborns.
**Option B:** Cerebral edema can cause ventriculomegaly, but it is typically a transient and reversible condition, whereas Dandy-Walker malformation is a congenital defect.
**Option C:** Bacterial meningitis can cause ventriculomegaly, but it is a secondary cause and not the most common cause of ventriculomegaly in newborns.
**Clinical Pearl / High-Yield Fact**
The Dandy-Walker malformation is a congenital defect that can be associated with other anomalies, such as heart defects, cleft palate, and developmental delays. It is essential to consider this diagnosis in newborns with ventriculomegaly and to perform thorough imaging studies to confirm the diagnosis.
**Correct Answer:** C.