NORCET 9 Mains - 2025: Stenosis/atresia of the foramina of Luschka and Magendie is characteristic of which condition?& x20;

NORCET 9 Mains - 2025

Pathology & Genetics

Easy

Appeared in: NORCET 9 Mains - 2025

Explanation

Dandy-Walker malformation is a congenital brain anomaly primarily affecting the cerebellum and the fourth ventricle.
Its defining feature is the developmental failure (atresia or stenosis) of the foramina of Luschka and Magendie, which are the exit pathways for CSF from the fourth ventricle.
This obstruction leads to a classic triad: cystic dilation of the fourth ventricle, complete or partial absence (agenesis) of the cerebellar vermis, and an enlarged posterior fossa.
The resulting buildup of CSF causes non-communicating hydrocephalus, typically presenting in infancy.

Option A: Normal pressure hydrocephalus is a communicating hydrocephalus, meaning there is no physical obstruction within the ventricular system. The problem lies with the poor absorption of CSF in the subarachnoid space.
Option B: Aqueductal stenosis is a blockage of the aqueduct of Sylvius, which is located between the third and fourth ventricles. The question specifies an obstruction at the outlets of the fourth ventricle.
Option C: The primary defect in Arnold-Chiari malformation is the downward herniation of the cerebellum and/or brainstem through the foramen magnum. While this can secondarily obstruct CSF flow, it is not defined by atresia of the foramina of Luschka and Magendie.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Congenital brain malformations and their effect on cerebrospinal fluid (CSF) circulation as background academic context rather than a clinical decision trigger.
Nurses caring for infants must perform routine neurological assessments, including measuring head circumference, palpating fontanels, and observing for signs of increased intracranial pressure (ICP) like irritability, poor feeding, vomiting, and the 'setting-sun' eye sign.
A rapidly increasing head circumference is a key indicator of hydrocephalus and requires prompt reporting to the physician for further investigation.
Post-operatively, after a shunt placement for hydrocephalus, nurses must monitor for signs of shunt malfunction, which mimic the signs of increased ICP, as this is a medical emergency.

How to Approach the Question

First, identify the key anatomical terms in the question: 'foramina of Luschka and Magendie'.
Recall the function of these structures. They are the outlets that allow cerebrospinal fluid (CSF) to exit the fourth ventricle.
Consider the term 'stenosis/atresia', which means narrowing or absence. The question is asking what condition results from the blockage of these specific outlets.
Evaluate each option based on this understanding:
Does NPH involve a blockage here? No, it's an absorption problem.
Does aqueductal stenosis involve a blockage here? No, it's a blockage before the fourth ventricle.

Concept Tested & Keywords

Concept Tested: Congenital brain malformations and their effect on cerebrospinal fluid (CSF) circulation.
Stem keywords: Stenosis, atresia, foramina of Luschka, foramina of Magendie
Lead-in keywords: characteristic of

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E6 Nelson Textbook of Pediatrics(2024) — Volume 2 pp. 1382-1384, 1386-1388