Name two cortical migration disorders besides lissencephaly.

Name two cortical migration disorders besides lissencephaly.

• A. Pachygyria and polymicrogyria
• B. Microcephaly and anencephaly
• C. Agenesis of the corpus callosum and holoprosencephaly
• D. Dandy-Walker malformation and Chiari II

Answer: (A)

Neuronal migration is the process that moves developing neurons from their birthplace to the correct cortical layers. When this migration or the subsequent cortical organization goes awry, cortical migration disorders arise. Lissencephaly represents the smooth-brain end of this spectrum, and two other examples are pachygyria and polymicrogyria. Pachygyria has broad, fewer gyri with shallow grooves, reflecting partial migration failure and altered cortical development. Polymicrogyria shows many small, irregular gyri with abnormal layering, indicating more extensive disruption of cortical organization. These conditions commonly present with seizures and developmental delays. The other options describe brain malformations not primarily due to migration defects, such as neural tube defects, midline forebrain abnormalities, or hindbrain malformations.

Neuronal migration is the process that moves developing neurons from their birthplace to the correct cortical layers. When this migration or the subsequent cortical organization goes awry, cortical migration disorders arise. Lissencephaly represents the smooth-brain end of this spectrum, and two other examples are pachygyria and polymicrogyria. Pachygyria has broad, fewer gyri with shallow grooves, reflecting partial migration failure and altered cortical development. Polymicrogyria shows many small, irregular gyri with abnormal layering, indicating more extensive disruption of cortical organization. These conditions commonly present with seizures and developmental delays. The other options describe brain malformations not primarily due to migration defects, such as neural tube defects, midline forebrain abnormalities, or hindbrain malformations.