Question:
What is the most likely diagnosis based on the MRI findings?
What is the most likely diagnosis based on the MRI findings?
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Children with lissencephaly typically present with severe psychomotor retardation, failure to thrive, microcephaly, and intractable epilepsy.
Mutations in the LIS1 or DCX (Doublecortin) genes are common molecular causes of this neuronal migration defect.
Mutations in the LIS1 or DCX (Doublecortin) genes are common molecular causes of this neuronal migration defect.
Updated On: Sep 3, 2026
- Lissencephaly
- Schizencephaly
- Holoprosencephaly
- Porencephaly
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The Correct Option is A
Solution and Explanation
Concept:
The question tests the radiological identification of congenital malformations of cortical development using an MRI scan of the brain.
(Assuming the classic imaging representation as per the provided correct answer).
Explanation:
• The term Lissencephaly literally translates to "smooth brain".
• It represents a spectrum of severe neuronal migration disorders where the cerebral cortex lacks the normal convolutions (gyri and sulci). This can manifest as complete agyria (total absence of gyri) or pachygyria (few, broad gyri).
• On an axial MRI, the classic findings of lissencephaly include a completely smooth cortical surface, a significantly thickened cortex, and a reduced amount of underlying white matter.
• Additionally, the brain often takes on a characteristic "figure-of-eight" or hourglass appearance due to the shallow or absent sylvian fissures.
• Option (B), Schizencephaly, is characterized by abnormal, fluid-filled clefts extending from the ependyma of the ventricles all the way to the pia mater on the cortical surface, usually lined by heterotopic gray matter.
• Option (C), Holoprosencephaly, is a failure of the embryonic forebrain to divide into distinct bilateral hemispheres, resulting in a single fused ventricle and fused midline structures.
• Option (D), Porencephaly, involves the presence of cystic cavities or cysts within the brain parenchyma, usually resulting from early ischemic or hemorrhagic insults rather than a primary migration defect.
Final answer:
The smooth appearance of the cerebral cortex lacking normal gyri and sulci on MRI is diagnostic of Lissencephaly.
The question tests the radiological identification of congenital malformations of cortical development using an MRI scan of the brain.
(Assuming the classic imaging representation as per the provided correct answer).
Explanation:
• The term Lissencephaly literally translates to "smooth brain".
• It represents a spectrum of severe neuronal migration disorders where the cerebral cortex lacks the normal convolutions (gyri and sulci). This can manifest as complete agyria (total absence of gyri) or pachygyria (few, broad gyri).
• On an axial MRI, the classic findings of lissencephaly include a completely smooth cortical surface, a significantly thickened cortex, and a reduced amount of underlying white matter.
• Additionally, the brain often takes on a characteristic "figure-of-eight" or hourglass appearance due to the shallow or absent sylvian fissures.
• Option (B), Schizencephaly, is characterized by abnormal, fluid-filled clefts extending from the ependyma of the ventricles all the way to the pia mater on the cortical surface, usually lined by heterotopic gray matter.
• Option (C), Holoprosencephaly, is a failure of the embryonic forebrain to divide into distinct bilateral hemispheres, resulting in a single fused ventricle and fused midline structures.
• Option (D), Porencephaly, involves the presence of cystic cavities or cysts within the brain parenchyma, usually resulting from early ischemic or hemorrhagic insults rather than a primary migration defect.
Final answer:
The smooth appearance of the cerebral cortex lacking normal gyri and sulci on MRI is diagnostic of Lissencephaly.
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