What is the cause of the hydranencephaly? Select one: a. Aqueductal stenosis b. Subaranchoid stenosis c. Overproduction of CSF d. Internal carotid arteries blockage

The correct answer is d.

Explanation:

Hydranencephaly is a rare congenital anomaly characterized by the absence and replacement of the cerebral hemispheres by cerebrospinal fluid and necrotic remains, with preservation of the membranes (leptomeninges), within a skull of normal capacity and shape. It is the most severe form of cortical destruction cerebral bilateral and is considered an extreme form of porencephaly (focal cystic cavity). It mainly affects the territory of the internal carotid artery and middle cerebral artery, with preservation of the territories supplied by the vertebrobasilar arteries. The most accepted etiology is carotid vascular insufficiency, due to multiple causes (bleeding, placental thromboembolism, arteritis, vascular malformations, among others).

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.