Neuro -- Malformations Of Cortical Development

Front 1

1. What is hemimegalencephaly?
2. What is the imaging appearance?

Back 1

1.
- Disorder of NEURONAL and GLIAL PROLIFERATION.
- Results in ENLARGEMENT of all or part of a CEREBRAL HEMISPHERE.
- Associated with NEURONAL MIGRATION DEFECTS -- polymicrogyria, pachygyria, and heterotopia
2.
- Enlargement of at least one lobe of the cerebral hemisphere.
- Enlargement of lateral ventricular atrium and straightening of the frontal horn.
- Neuronal migration defects -- polymicrogyria, pachygyria, and heterotopia.
- WM hyperintensity on T2WI.
- Ipsilateral somatic hemihypertrophy.

Front 2

1. What are the different types of gray matter heterotopias?
2. What other disease processes give rise to subependymal nodules?
3. How do you distinguish subependymal nodular heterotopia from subependymal nodules of tuberous sclerosis?
4. What are the imaging findings in band heterotopia?
5. What is the inherentance pattern of band heterotopia?

Back 2

1. Heterotopias refer to gray matter in abnormal locations. NODULAR HETEROTOPIA may be SUBCORTICAL or SUBEPENDYMAL in location.
BAND-LIKE heterotopia.
Note: Subcortical heterotopia typically extends from the cortical surface to the ventricular surface.
2.
- Subependymal nodules of tuberous sclerosis
- Subependymal spread of neoplasm.
3. Subependymal nodular heterotopia follows SI of gray matter, while the subependymal nodules of tuberous sclerosis are similar to white matter.
4. Symmetrical and circumferential band of gray matter within the subcortical white matter. However, band heterotopia may be partial and asymmetrical. When partial, the frontal lobes are most commonly involved. PET scan demonstrates increased FDG uptake in the band that is similar to overlying cortex.
5. X-linked dominant with affected females passing on the disease to their daughters. Sons of affected females demonstrate lissencephaly.

Front 3

1. What is the etiology of lissencephaly?
2. What are the imaging findings of lissencephaly?
3. What infection can mimic the appearance of lissencephaly?

Back 3

1. Neuronal migrational abnormality that results in a 4 layer cortex, instead of the normal 6.
2.
- HOURGLASS or FIGURE-OF-EIGHT configuration on axial images.
- LAMINATED CORTEX -- appears as thin outer layer and a thicker inner layer separated by a layer of normal appearing white matter.
- Failed opercularization of the sylvian fissures (absence of the normal temporal lobes lateral to the sylvian fissures).
- Global reduction in the number of gyri and sulci
- Ventriculomegaly
- Hypoplasia of the CC
3. Congenital cytomegalovirus infection

Front 4

1. What is polymicrogyria?
2. What is imaging appearance of polymicrogyria?
3. What other abnormality appears similar to polymicrogyria?
4. What congenital infection can result in polymicrogyria?

Back 4

1. Literally means too many small gyri. It is characterized by numerous abnormally small convolutions on the brain surface.
2.
- IRREGUAR, BUMPY thickening of the cortex
- Abnormal cortex is isointense to normal cortex on all sequences.
3. Pachygyria - SMOOTH broad flat gyri.
4. CMV

Front 5

1. What is schizencephaly?
2. How do you differentiate schizencephaly from porencephalic cyst?
3. What structure may be absent in patients with schizencephaly?
4. What finding can help to diagnose closed lip schizencephaly?

Back 5

1. Gray matter lined cleft that extends from the pial surface to the ventricle with the subarachnoid space in continuity with the ventricular CSF.
2. Porencephalic cysts are secondary to a destructive process and are lined by gliotic white matter rather than dysplastic gray matter.
3. The septum pellucidum is absent in approximately 45% of cases of schizencephaly.
4. Diagnosis of a closed lip schizencephaly can be subtle -- look for a characteristic dimple or outpouching of CSF along the ventricular surface representing the communication with the cleft.

Front 6

What are the 3 broad categories of malformations of cortical development?

Back 6

1. Abnormalities of cellular proliferation in the germinal zone.
2. Abnormalities of cellular migration to the developing cerebral cortex.
2. Abnormalities of cellular organization within the cortex.

Front 7

1. What is the clinical presentation of cortical dysplasia?
2. What are the findings of cortical dysplasia?

Back 7

1. Medically refractory seizures.
2.
- Blurring of the gray matter-white matter junction with abnormal T2/FLAIR hyperintensity noted at the gray-white matter junction.
- In transmantle dysplasia, the abnormal signal may be observed to extend from the cortex towards the ventricular surface in a linear fashion.

Front 8

1. What is schizencephaly?
2. How do you tell the difference between schizencephaly and porencephalic cyst?

Back 8

1. CSF filled cleft extending from the surface of the cortex to the lining of the ventricle. Clefts may either be closed or open lipped, uni- or bilateral.
2. Schizencephaly is lined by gray matter, whereas a porencephalic cyst is lined by gliotic white matter.