Which of the following statements is true about Chiari IV malformation?

Appeared in: DSSSB October 2024

Explanation

Chiari IV malformation is defined by severe underdevelopment (hypoplasia) or complete absence (aplasia) of the cerebellum.
This is the rarest and most severe form of Chiari malformation.
Unlike Types I, II, and III, Chiari IV is not characterized by the downward herniation or displacement of brain tissue through the foramen magnum.
Due to the severe lack of cerebellar development, this condition is often incompatible with long-term survival.

Option B: This statement describes Chiari I malformation, which is the most common and least severe type, where only the cerebellar tonsils are displaced downwards.
Option C: This describes Chiari III malformation, a rare and severe condition where parts of the cerebellum and brainstem herniate through an abnormal opening in the back of the skull (an encephalocele).
Option D: This statement is characteristic of Chiari II malformation (also known as Arnold-Chiari malformation), where the cerebellar vermis, tonsils, and medulla are displaced downwards. It is almost always associated with myelomeningocele.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification and characteristics of Chiari malformations as background academic context rather than a clinical decision trigger.
Accurate identification of the type of Chiari malformation is crucial for prognosis and management. While Types I and II may be managed surgically, Types III and IV have a very poor prognosis.
Nurses caring for infants with neurological deficits must be aware of these conditions. An infant with a myelomeningocele should be assessed for signs of Chiari II malformation, such as difficulty swallowing, weak cry, and breathing problems.
Genetic counseling is important for families, as some forms of posterior fossa malformations can be linked to genetic syndromes.

How to Approach the Question

First, identify the core concept of the question, which is the definition of 'Chiari IV malformation'.
This is a factual recall question that requires knowledge of the different types of Chiari malformations.
Mentally review or list the defining features of each type (I, II, III, and IV).
Compare the features of Chiari IV (cerebellar hypoplasia/aplasia) with the given options.
Select the option that correctly matches the definition of Chiari IV.
Eliminate the other options by identifying which type of Chiari malformation they describe.

Concept Tested & Keywords

QbvBjTM-TrDEee6358a09n

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1382-1384

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 1245-1247

Practise the full DSSSB October 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.