Not true regarding Dandy Walker cyst ?
**Core Concept**
A Dandy-Walker cyst is a congenital malformation of the brain characterized by the partial or complete agenesis of the cerebellar vermis, associated with enlargement of the fourth ventricle and hydrocephalus. This condition often results from a defect in the development of the roof of the fourth ventricle, leading to a cystic expansion.
**Why the Correct Answer is Right**
The correct answer will be a statement that is false regarding Dandy-Walker cyst. To determine this, we need to evaluate each option. Dandy-Walker cyst is often associated with other congenital anomalies, such as microcephaly, intellectual disability, and spasticity. The cerebellar vermis is usually hypoplastic or absent in Dandy-Walker cyst, leading to impaired coordination and balance. The fourth ventricle is typically dilated, causing hydrocephalus.
**Why Each Wrong Option is Incorrect**
* **Option A:** Not a characteristic of Dandy-Walker cyst. The correct feature is the partial or complete agenesis of the cerebellar vermis.
* **Option B:** Not true. Dandy-Walker cyst is often associated with hydrocephalus due to the obstruction of cerebrospinal fluid (CSF) pathways.
* **Option C:** Not a feature of Dandy-Walker cyst. The condition is characterized by the enlargement of the fourth ventricle, not the third.
* **Option D:** Not a characteristic of Dandy-Walker cyst. The condition is often associated with spasticity and impaired coordination, not weakness.
**Clinical Pearl / High-Yield Fact**
Dandy-Walker cyst is a congenital malformation that often presents with hydrocephalus, intellectual disability, and spasticity. It is essential to recognize the characteristic features of this condition to make an accurate diagnosis.
**Correct Answer:** D.