6. REVIEW OF LITERATURE
• TYPES OF LISSENCEPHALY
• Classic (Type I) Lissencephaly (4-Layer Lissencephaly)
• Patients with classic lissencephaly may have a smooth brain surface in the
complete form, or more commonly, they have a smooth surface with some
gyral formation along the inferior frontal and temporal lobes in the
incomplete form.
• This anomaly results from arrest of the migration process. Patients The
malformation is characterized by complete agyria in the complete form or
parieto-occipital agyria with frontotemporal pachygyria in the incomplete
form. The cortex is thick because it encompasses radial columns of the
arrested cells.
• The subcortical white matter is thin, with a lack of the normal gray-white
matter interdigitation.
• There is a circumferential band of high signal intensity on T2-weighted
images, most prominent in the parieto-occipital cortex, corresponding to a
sparse cell zone with increased water content.
8. LISSENCEPHALY TYPE II
• Cobblestone lissencephaly is characterized by a nodular
brain surface, ocular anomalies, and congenital muscular
disorders.
• Cobblestone cortex results from overmigration of the
neuroblasts
and glial cells beyond the external glial limitations into the
subarachnoid space .
• It includes a spectrum of anomalies with Walker-Warburg
syndrome (WWS) being the most severe form; Fukuyama
congenital muscular dystrophy (FCMD), the mildest form;
and muscle-eye-brain (MEB) disease, the intermediate form
11. WHY NOT LISSENCEPHALY
• This detailed review of a large number of MR images of
patients with various types of lissencephaly showed
developmental abnormalities of the major forebrain
commissures in almost all patients;
• The CC was the commissure most commonly involved.
• Although many variations were seen, the most common
anomaly consisted of an absent rostrum, a small inferior
genu, and a small or abnormally shaped splenium: this
configuration has been defined as hypogenetic.
• In addition, malformations secondary to specific mutations
and presumed mutations seemed to have a characteristic
overall shape of the CC.
• Kara AJNR 31 Oct 2010 www.ajnr.org
12.
13. CAUSES OF MEGA CORPUS CALLOSUM
• A mega-corpus callosum is an exceptional
finding in the neurologic setting, with only a
few reports in the literature.
• In most cases, the abnormal development of
the corpus callosum results in complete or
partial agenesis and thinning.
• Two genetic syndromes merit specific
mention: 1. neurofibromatosis type1 and
2.Cohen syndrome
14. POLYMICROGYRIA
• PMG is characterized by many small prominent convolutions
separated by shallow sulci with an irregular appearance of the
cortical surface and cortical white matter.
• It results from prenatal infection, ischemia, or exposure to toxins or
chromosomal abnormality.
• The malformation is characterized by a heterogeneous collection of
neurons and derangement of the normal 6-layer lamination of the
cortex. The sulci may be obliterated and bridged by fusion of their
superficial cellular layers, particularly the molecular one.
• The anomaly can be unilateral or bilateral, small or
large, symmetric or asymmetric.
• It is commonly located in regions adjacent to the Sylvian fissures
(ie, the posterior frontal lobe, the superior temporal lobe, and the
inferior parietal lobe).
15. POLYMICROGYRIA CLASSIFICATION
• Pattern I is characterized by a small fine undulating
cortex with normal cortical thickness (3–4 mm). This
pattern is seen in the anterior frontal region, mainly in
infants younger than 12 months.
• Pattern II has a bumpy cortical appearance with less
undulation. The cortex is abnormally thickened (5–7
mm) with an irregular cortical–white matter junction.
This pattern is noted in infants older than 18 months. It
involves mainly the frontal, parietal, and perisylvian
regions. Differentiation between the cortex and
underlying white matter is poor on T1- weighted
images.
16.
17. HOW DIFFERENT IS THIS CASE
• Poly microgyria
• Enlarged Corpus callosum
• Psychomotor retardation.
18. PMMC
• A constellation of findings such as megalencephaly, a mega-
corpus callosum, a complete lack of motor
development, perisylvian polymicrogyria, and distinct facies
has been designated megalencephalypolymicrogyria-
mega-corpus callosum syndrome (Online Mendelian
Inheritance in Man 603387)
• Bindu PS, Taly AB, Sinha S, Bharath RD. Mega-corpus
callosum, polymicrogyria, and psychomotor retardation syndrome. Pediatr
Neurol 2010;42:129-132.
• Mega-Corpus Callosum, Polymicrogyria, and Psychomotor Retardation:
Confirmation of a Syndromic EntityT. M. Pierson1, R. A. Zimmerman2, G. I.
Tennekoon3, C. G. Bönnemann4
19. PMMC
• Megalencephaly may or may not be
associated.
• Mega corpus callosum, polymicrogyria, epilepsy and psychomotor
retardationGyurgyinka Gergev, Nóra Szabó, Éva Romhányi, Sándor
Túri, László Sztriha European Paediatric Neurology Society
Congress, 9th EPNS Congress
