CLINICAL MEDICINE

Detailed explanation-1: -Aqueductal stenosis is a narrowing of the aqueduct of Sylvius which blocks the flow of cerebrospinal fluid (CSF) in the ventricular system. Blockage of the aqueduct can lead to hydrocephalus, specifically as a common cause of congenital and/or obstructive hydrocephalus.

Detailed explanation-2: -A blockage of the proximal cerebral aqueduct causes the tectum to be pushed into the tegmentum. The distal cerebral aqueduct and fourth ventricle appear normal. For distal aqueductal stenosis, the proximal portion of the aqueduct becomes dilated and takes on a beaked appearance.

Detailed explanation-3: -Congenital aqueductal stenosis is a form of noncommunicating hydrocephalus in which a complete or partial obstruction of CSF flow at the aqueduct of Sylvius during fetal life results in dilation of the lateral and third ventricles and increased intracranial pressure.

Detailed explanation-4: -Often the etiology of hydrocephalus is due to blockage of the cerebrospinal fluid exiting the ventricles. The most common site of this blockage is at the cerebral aqueduct, called aqueductal stenosis. Though this occurs more commonly in children, it can present in adulthood.