The brain tumor located in aqueduct of Sylvius causes hydrocephalous by

RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Pathology & Genetics

Medium

Appeared in: RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Explanation

The aqueduct of Sylvius is the narrowest channel in the ventricular system, connecting the third and fourth ventricles.
A tumor, being a physical mass, located in this narrow passage will inevitably cause a blockage or obstruction.
This obstruction prevents the normal circulation of cerebrospinal fluid (CSF), leading to its accumulation in the ventricles located before the blockage (the lateral and third ventricles).
This specific condition is known as non-communicating or obstructive hydrocephalus, where the primary problem is a physical barrier to CSF flow.

Option A: This is a rare cause of hydrocephalus. The tumor described is located in the aqueduct, not the choroid plexus where CSF is produced.
Option B: This option is too general and not as precise as the correct answer. While obstruction does lead to reduced drainage, 'obstructing the flow' describes the specific primary mechanism of action of a tumor in a narrow channel.
Option C: This mechanism describes communicating hydrocephalus, where CSF can flow out of the ventricles but is not properly absorbed by the arachnoid villi in the subarachnoid space.

Visual 1: Diagram: Sagittal view of the brain showing the ventricular system and the normal pathway of CSF flow, highlighting the narrow aqueduct of Sylvius.
Visual 2: Illustration: Comparison of non-communicating (obstructive) hydrocephalus with a blockage in the aqueduct, and communicating hydrocephalus with a problem at the arachnoid granulations.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of Obstructive Hydrocephalus as background academic context rather than a clinical decision trigger.
Nurses must vigilantly monitor patients with suspected hydrocephalus for signs of increased intracranial pressure (ICP), such as headache, vomiting, changes in consciousness, and papilledema.
In infants, a key nursing assessment is the serial measurement of head circumference, as rapid growth is a primary indicator of hydrocephalus.
What if? If the patient's history included a recent bout of bacterial meningitis instead of a tumor, the most likely cause of hydrocephalus would be decreased CSF absorption (communicating hydrocephalus), as inflammatory exudate can block the arachnoid villi.

How to Approach the Question

First, identify the key anatomical structure mentioned: the 'aqueduct of Sylvius'.
Recall its primary characteristic: it is the narrowest channel in the cerebrospinal fluid (CSF) pathway.
Next, consider the pathology described: a 'brain tumor', which is a physical, space-occupying mass.
Synthesize these two facts: placing a mass in a very narrow channel will physically block it.
Evaluate the options based on this understanding. 'Obstructing the flow of CSF circulation' is the most direct and accurate description of this physical blockage.

Concept Tested & Keywords

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