CASE 769 Published on 06.03.2001
0

Lissencephaly

Section

Neuroradiology

Case Type

Clinical Cases

Authors

R.N.Sener

Connected authors
Patient

2 years, male

Categories
No Area of Interest ; Imaging Technique MR, MR-Functional imaging
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Clinical History
Developmental delay, seizures
Imaging Findings
Presented with severe developmental delay, and epilepsy. MRI examination was performed at 1.5 Tesla, and T1 and T2-weighted images were acquired as well as a PSIF sequence. PSIF is an anisotropic diffusion sequence(reverse FISP, fast imaging in steady state precession).
Discussion
The normal cerebral cortex is approximately 3-5mm in thickness. A cortical thickness of 5-8 mm could reflect polymicrogyria, and thicker cortices are usually seen in agyria and pachygyria (care should be exercised to not to overestimate cortical thickness in oblique sections). In agyria the brain surface is smooth without any normal gyrus. In pachygyria usually a a few normal-appearing gyri are present especially in the occipital and temporal lobes. Changes consistent with agyria and pachygyria are usually seen together, which is referred to as lissencephaly. Lissencephalic brains may be in isolation or may be associated with Walker-Waburg syndrome (hypotonia, ocular malformations, encephalocele, and hydrocephalus), and Fukuyama type muscular dystrophy (congenital muscular dystrophy, and ocular malformations). Also, lissencephalic brains may be very small in size (microbrain), or may show extremely thin cortices (micrencephalia vera).
Differential Diagnosis List
Lissencephaly
Final Diagnosis
Lissencephaly
Case information
URL: https://www.eurorad.org/case/769
DOI: 10.1594/EURORAD/CASE.769
ISSN: 1563-4086
Figure 1

MRI findings

MRI findings
T1-weighted (inversion recovery) image reveals a smooth brain surface with a few shallow sulci. The cortex is thick (15 mm), and the white matter is quite thin. In lissencephaly -from outer to inner side- the cortex usually has four layers of cells, and an intervening cell-sparse layer over a thick layer of underlying ectopic neurons. This cell-sparse zone is seen as a hypointense layer in this inversion recovery image (the normal cortex has 6 layers of cells).
MRI findings
Coronal, T2-weighted image shows the cell-sparse zone as a hyperintense line. Note normal cerebellum.
MRI findings
Sagittal, T1-weighted image reveals a diffusely thin corpus callosum. The configuration of the corpus callosum is dome-like, a common finding in lissencephalies.
MRI findings
PSIF image reveals the cell-sparse layer with high signal (pixel value: 118). Another high signal area is demonstrated in the right frontal region (pixel value: 124). These are in conformity with defective myelination. A relatively normal pixel value of 104 is demonstrated, probably representing normal myelination. In anisotropic diffusion imaging (PSIF), pixel values ranging from 60 to 110 are generally observed in the normal parenchyma of normal individuals