Following features differentiate hydranencephaly from hydrocephalus
**Core Concept**
Hydranencephaly and hydrocephalus are two distinct cerebral malformations that can present with similar symptoms, but they have distinct underlying pathologies. Hydranencephaly involves the near-total absence of the cerebral hemispheres, replaced by fluid-filled sacs, whereas hydrocephalus is characterized by an accumulation of cerebrospinal fluid (CSF) within the ventricles of the brain.
**Why the Correct Answer is Right**
Hydranencephaly is a rare congenital anomaly that results from the premature closure of the developing brain's neural tube, leading to the absence of the cerebral hemispheres. In contrast, hydrocephalus occurs due to an imbalance between the production and absorption of CSF, causing an accumulation of fluid within the ventricles. This fluid accumulation can lead to increased intracranial pressure and subsequent brain damage. The key distinction between hydranencephaly and hydrocephalus lies in the underlying cause and the resulting brain anatomy.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because hydrocephalus involves an accumulation of CSF within the ventricles, whereas hydranencephaly involves the near-total absence of the cerebral hemispheres.
**Option B:** This option is incorrect because hydranencephaly is a congenital anomaly, whereas hydrocephalus can be caused by various factors, including trauma, infection, or tumors.
**Option C:** This option is incorrect because the presence of CSF-filled sacs is a characteristic feature of hydranencephaly, whereas hydrocephalus is characterized by an accumulation of CSF within the ventricles.
**Option D:** This option is incorrect because while both conditions can present with increased intracranial pressure, the underlying cause and brain anatomy differ between hydranencephaly and hydrocephalus.
**Clinical Pearl / High-Yield Fact**
One key distinction between hydranencephaly and hydrocephalus is that hydranencephaly is often associated with a more pronounced reduction in brain volume and a more severe developmental delay. Additionally, hydranencephaly is typically diagnosed prenatally or in infancy, whereas hydrocephalus can be diagnosed at any age.
**Correct Answer: C.**