Case record...Cortical dysplasia http://yassermetwally.com http://yassermetwally.net

1. CASE OF THE WEEK
PROFESSOR YASSER METWALLY
CLINICAL PICTURE
CLINICAL PICTURE:
9 years old female patient presented clinically with Lennox-Gastaut syndrome.
RADIOLOGICAL FINDINGS
RADIOLOGICAL FINDINGS:
Figure 1. Postcontrast CT scan showing Lissencephaly, pachygyria,and subependymal nodular heterotopia.
Figure 2. Postcontrast CT scan
showing Lissencephaly,
pachygyria,and subependymal
nodular heterotopia. Also notice
cerebellar hypoplasia and mild
central atrophy.
DIAGNOSIS:

2. DIAGNOSIS: CORTICAL DYSPLASIA
DISCUSSION
DISCUSSION:
Abnormalities have long been recognized in the brains of children with developmental delay and seizures. The
advent of newer imaging techniques, such as high-resolution (thin slice three-dimensional gradient recalled echo
[GREI) magnetic resonance (MR) imaging and surface reconstructions of three-dimensional data sets, has led to a
greater in vivo understanding of these malformations. There has been reclassification of the disorders of cortical
malformations according to embryologic stages of brain cortex development at which these malformations are
proposed to have occurred. These stages are cellular proliferation, cellular migration to the developing cortex, and
cortical organizations.
MALFORMATIONS OF ABNORMAL CELL PROLIFERATION
 Nonneoplastic
The earliest lesions resulting in cortical malformations are those with onset during the period of cellular
proliferation in the germinal zones. During the seventh fetal week, germinal layers begin to form in the vesicle walls
of telencephalic outpouchings (vesicles) at the foramina of Monro. Cortical malformations occurring during this
stage of neuronal and glial proliferation may be generalized, multifocal, or focal. Generalized malformations of
abnormal cell proliferation include microcephaly with diminished cortical thickness or with diminished sulcation.
Commonly imaged focal or multifocal lesions include nonneoplastic disorders, such as hemimegalencephaly, focal
cortical dysplasia (with balloon cells), and forme fruste tuberous sclerosis.
Hemimegalencephaly may be associated with neurocutaneous or hemiovergrowth syndromes, such as
hypomelanosis of Ito, epidermal nevus syndrome, or neurofibromatosis type 1. Proposed causes for hemispheric
overgrowth in hemimegalencephaly include abnormal cellular proliferation and heteroploidy, defective cellular
metabolism, or possibly an insult to the developing brain in the mid to late second trimester. In the event of a later
insult to the developing brain, brain plasticity allows for the development of new synapses in the damaged brain,
permitting the persistence of supernumerary axons and the potential for white matter overgrowth. Neuropathologic
and neuroimaging features in hemimegalencephaly are abnormal neurons, lack of gray-white matter demarcation,
disarrayed cortical lamination, gray matter heterotopias, broad gyri, and signal changes reflecting hypomyelination
and gliosis. It is postulated that foci of agyria, with macroscopic heterotopias, extensive white matter gliosis, and
less hemispheric white matter overgrowth, likely result from an earlier, more severe insult with destruction of the
radial glial fibers. The variable patterns of cortical and white matter involvement demonstrated with neuroimaging
likely reflect the variability in severity and timing of the precipitating insult. [1,5,19,23]
Figure 1. Tl -weighted (TR 600/TE 15) and T2-weighted (I R 2800/ TE 90) axial images (A and B) demonstrate
overgrowth of the right cerebral hemisphere in a patient with developmental delay, seizures, and

3. hemimegalencephaly. Note the abnormal white matter signal and the unilateral ventriculomegaly.
Focal cortical dysplasia is characterized by neocortical abnormalities. The pathologic spectrum of focal cortical
dysplasia includes significant abnormalities of neuronal size, shape, orientation, and lamination; indistinctness of
the gray-white junction; and variability in cortical thickness. Large bizarre neurons with abnormal Nissl patterns,
giant neurons, binucleate neurons, a variable degree of cortical gliosis, and balloon cells with abundant pale
eosinophilic cytoplasm are found. These balloon cells are similar to those seen in the cortical tubers and white
matter lesions of tuberous sclerosis, and there is much overlap in the pathology of focal cortical dysplasia and
tuberous sclerosis. Failure of myelin arborization, blurring of gray-white margins, variable sulcal depth and
cortical thickness, and occasional hazy or dystrophic calcification may be appreciated on neuroimaging. Evidence
of dual pathology, or focal cortical dysplasia in association with hippocampal sclerosis, should be sought.
[8,14,17,21,26,28,32]
Figure 2. Tl -weighted (TR 600/TE 15) sagittal (A) and axial
images (B), and T2-weighted (TR 3000/ TE 120) axial image (C)
in a child with severe microcephaly showing a thin cortical
ribbon. A Tl -weighted axial image (D) in a second child with a
similar degree of microcephaly reveals fewer gyri and less well
developed sulcation.
Imaging features in limited or forme fruste tuberous sclerosis include demonstration of a solitary smooth
pyramidal-shaped gyri with a central depression and abnormal signal of the subcortical white matter. The cortical
and subcortical lesions are uncommonly calcified, tend not to enhance, and are best demonstrated on MR. These
children lack the calcified subependymal nodules of tuberous sclerosis as well as other organ system lesions. The
cortical tubers are characterized by aberrant neurons, scattered balloon cells, and gliosis. The white matter lesions
of tuberous sclerosis are characterized by decreased myelin and accumulations of balloon cells. Although there are
similarities in the pathology of focal cortical dysplasia and the form fruste of tuberous sclerosis, the latter has, in
general, more abundant balloon cells. [15,17, 18,22,24]
 Neoplastic
Lesions of proliferation after an abnormal induction event during brain development may be malformative,
hamartomatous, neoplastic, or a combination. Malformative disorders consisting of neoplasias on a background of

4. disordered cortex or in association with focal cortical dysplasia include dysembryoplastic neuroepithelial tumor and
ganglioglioma. [5,7]
 Dysembryoplastic neuroepithelial tumors
Dysembryoplastic neuroepithelial tumors are supratentorial, predominantly temporal lobe tumors that are
typically multinodular with a heterogeneous cell composition, including oligodendrocytes, neurons, astrocytes, and
other cells. These lesions are typically fairly well-demarcated, wedge-shaped lesions extending from the cortex to
the ventricle. Calcification, enhancement, and peritumoral edema are lacking on neuroimaging studies. These low-
attenuation lesions may suggest an infarct on computed tomography (CT), although there is no volume loss over
time, and scalloping of the inner table or calvarial bulging suggests slow growth. Lesions are low in signal on Tl-
weighted images and high in signal on T2- weighted images and often have a multinodular or pseudocystic
appearance. There is a spectrum of pathology in dysembryoplastic neuroepithelial tumors. On one end of the
spectrum are multinodular lesions with intervening malformed cortex, in which there is some hesitation to use the
designation tumor. On the other end are lesions, which are clearly neoplastic and have clinically demonstrated some
growth potential. Because the term dysembryoplastic neuroepithelial tumor has only recently been introduced, such
malformative and neoplastic lesions were previously labeled as hamartomas, gangliogliomas, or mixed gliomas.
[9,17,20]
Figure 3. A, Dysembryoplastic neuroepithelial tumour (frontobasal surgical specimen). Irregular thickening of the
cerebral cortex with multiple cortical and subcortical nodules. This complex tumour consists of a mixture of glial
cells and nerve cells and is often associated with dysplastic cortical foci. It can occur in any part of the brain and
generally causes long-standing focal seizures. B, Dysembryoplastic neuroepithelial tumour (MT x40).
Oligodendroglial-like cells arranged in groups or columns within a loose, microcystic matrix containing several
solitary "floating" neurons and numerous congestive capillaries. Calcifications are possible.

5. Figure 4. Dysembryoplastic neuroepithelial tumor. Wedge-shaped, nonenhancing, very low signal in- tensity lesion
on Tl -weighted (TR 600/TE 15) axial image (A) demonstrating very high signal intensity lesion on the T2-weighted
(TR 2800/TE 90) (B) axial image. Note the scalloping of the inner table, the multiple septations, and the lack of
vasogenic edema or mass effect on the adjacent brain and ventricle. Pathologic specimen (Figure 3A) demonstrates
nodules on an abnormal background of cortical dysplasia, and a specimen of one of the nodules seen on high power
(Fig.3B) demonstrates oligodendroglial-like cells, some of which are actually immature neurons.
 Gangliogliomas
Gangliogliomas are typically demonstrated within the temporal lobe. In one large series of 51 gangliogliomas, 84%
were found in the temporal lobe, 10% were found in the frontal lobe, 2% were found in the occipital lobe, and 4%
were found in the posterior fossa. These lesions are typically hypodense (60% to 70%) on CT, with focal
calcifications seen in 35% to 40%, contrast enhancement in 45% to 50%, and cysts in nearly 60%. The reported
incidence of calcifications demonstrated on imaging in pediatric gangliogliomas is higher, seen in 61% of one series
of 42 children. Features on MR imaging are less specific, with solid components isointense on T1-weighted images,
bright on proton density images, and slightly less bright on T2-weighted images. Although imaging features are not
specific, an enhancing, cystic temporal lobe lesion with focal calcification should suggest the diagnosis of
ganglioglioma. The pathologic features that suggest the diagnosis of ganglioglioma include a neoplastic glial and
neuronal component and calcification. Because calcifications are often poorly demonstrated on MR imaging and
because they increase specificity of imaging findings, documentation of calcium should be sought on CT after MR
imaging demonstration of a temporal lobe tumor. [11,27,33]
Figure 5. A large,calcified, enhancing ganglioglioma with heterogeneous signal is demonstrated within the occipital
lobe of a macrocephalic child on CT (A), and Tl -weighted (TR 600/TE 15) axial images before precontrast (B) and
after (C) contrast administration. Location of ganglioglioma in this child is atypical.

6. DISORDERS OF CELLULAR MIGRATION TO THE CORTEX
The onset of neuronal migration to the cortex occurs during the eighth fetal week. Initially, cells in the germinal
zone elongate with the nucleus remaining in the portion of cell that is furthest from the ventricular surface. After
mitosis, the newly formed cells are distant from the ventricular surface. Later in neuronal migration, as distance to
travel increases, migration occurs along the radial glial fibers (RGF), which span the distance from the ventricular
surface to pia. Disorders of neuronal migration occur when migration is halted. Abnormalities of neuronal
migration may occur with damage to the RGF by placental ischemia, infection (cytomegalovirus), or maternal
trauma or with altered chemotaxis of neurons along the fibers from toxin exposure or inborn errors of metabolism.
Diffuse disorders of disruption of neuronal migration include band heterotopia, classic (type 1) lissencephaly, and
cobblestone (type 2) lissencephaly. Marginal glioneuronal heterotopia and nodular cortical dysplasias, nests of
ectopic glial elements and gray matter within the leptomeninges and at the crown of the gyri, are believed to be the
result of overmigration, possibly through areas of superficial necrosis or disruption of the external glial limitans.
These findings, recognizable only on pathologic specimens, are believed to give rise to the lacy or cobblestoned
cortex in type 2 lissencephaly. More focal disorders of disrupted neuronal migration include subependymal or
subcortical neuronal ectopia and heterotopias. Disorders of neuronal migration are characterized on imaging
studies by gray matter localized along the pathways of migration to the cortex. These gray matter rests, nodules, or
masses share the attenuation (CT) and signal characteristics (MR imaging) of normal gray matter on all imaging
sequences. Small deposits of heterotopia may be identified with high-resolution gradient volume acquisitions, which
augment tissue contrast between gray and white matter. [3,5]
Figure 6. Pachygyric (A), and agyric (B) lissencephalic brain
Figure 7. A, Type II lissencephaly, Cobblestone lissencephaly (Walker-Warburg syndrome). The cortex is
lissencephalic and thickened, with an irregular gray matter-white matter junction that probably represents the
bundles of disorganized cortex surrounded by fibroglial tissue. The patient has been shunted for hydrocephalus.
The brain is hypomyelinated. B, Presumed microcephalia vera. The brain is completely smooth (lissencephaly) with
a very thin cortex. No layer of arrested neurons is present in the white matter. C, Presumed radial microbrain.
Axial T2- weighted image shows an immature gyral pattern and hypomyelination. Cortical thickness is normal.
This patient was profoundly microcephalic (head circumference 19 cm).

7. Band heterotopia results from an early arrest of neuronal migration and gives the appearance of a continuous
double cortex. The appearance has also been likened to a three-layer cake with the cortex and bilaterally
symmetric, circumferential, subcortical layers of band heterotopia separated from each other by a thin white
matter band. The cortex may be relatively normal or pachygyric. Shallow sulci are common. Band heterotopia has
been reported to be an X-linked disorder with heterozygous females demonstrating band heterotopia and
hemizygous males having classic lissencephaly. Seizures are common in band heterotopia, and mental retardation
may be mild or moderate. Severity of symptoms correlates with the degree of disorganization of the overlying
cortex, thickness of the continuous band of heterotopic gray matter, amount of T2 prolongation, and degree of
ventriculomegaly The brain in lissencephaly type I may have a smooth surface (complete lissencephaly) or may
have a nearly smooth surface with some gyral formation along the inferior frontal and temporal lobes. The thick
cortex has a four-layered cortex composed of a molecular outer layer, an outer cellular layer, a cell sparse layer,
and an inner cellular layer composed of arrested neurons. The arrest relates to a disruption of neuronal travel
along the RGF, either from laminar necrosis or from disrupted chemotaxis. Imaging demonstrates broad, flat gyri
with a thickened cortex and scanty white matter. Sylvian fissures are primitive, leading to an hourglass
configuration of the brain. Type 2 or cobblestone lissencephaly is recognizable by its irregular surface, abnormal
myelin, and the accompanying orbital and cerebellar anomalies. [2,10,29]
Figure 8. A, Band heterotopia with pachygyria. B, band heterotopia with mild periventricular nodular heterotopia
Figure 9. Subependymal nodular heterotopia

8. Periventricular nodular heterotopia may be solitary, isolated lesions or may diffusely line the walls of both lateral
ventricles. These lesions mimic the appearance of the subependymal tubers in tuberous sclerosis, although they do
not calcify. When diffuse and bilateral, periventricular nodular heterotopia may be associated with mild cerebellar
hypoplasia. Patients with periventricular or subependymal heterotopias may present with late-onset seizures,
acquire normal early milestones, have normal motor development, and be of average or above-average intelligence.
This disorder has been linked to markers in distal Xq28. Subcortical gray matter heterotopias also may be focal or
diffuse. The greater the heterotopic mass, the more dysplastic the overlying cortex. Those patients with thick
heterotopias and overlying gyral anomalies are more likely to have associated psychomotor delay. Deep infolding of
thickened cortex, or deep clefts lined by heterotopia, often frontal, may also occur and are frequently associated on
imaging with primitive vertical venous structures. [3,4,10,12,13,16]
DISORDERS OF CORTICAL ORGANIZATION
The primitive sylvian fissure is the first sulcus to form, at approximately 14 to 20 weeks, whereas the rolandic
fissure, the parieto-occipital, and the superior temporal gyri form later. By 32 to 33 weeks, large numbers of
cortical sulci are visible, and by 38 to 40 weeks, there is a nearly normal adult sulcal pattern. After full-term birth,
the sulci continue to deepen over the next weeks. The final group of disorders are those that are associated with
disruption of the process of gyral formation and subsequent cellular organization of the cortex. These disorders
include generalized polymicrogyria (PMG) or focal and multifocal disorders such as focal PMG, bilateral
symmetric PMG, and schizencephaly with or without PMG. The imaging appearance of dysplasias of cortical
organization includes abnormalities of the cortical gyral pattern without radiographically evident subjacent
heterotopias. The imaging appearance of generalized or focal polymicrogyria can be quite variable. Typically, there
is a thick cortex with many small gyri separated by shallow sulci. The gyri may, however, be so small that they are
difficult to discern on imaging. The appearance then is of a flat thickened cortex, simulating pachygyria or agyria.
Small areas of cortical thickening may be better defined with adjunctive three-dimensional MR reformatted
images. Bilateral opercular or perisylvian syndrome is a bilateral symmetric PMG disorder consisting of primitive
sylvian fissures, primitive draining veins, and symmetric involvement of the operculum with polymicrogyria or
pachygyria. Patients may present with seizures, motor and speech disorders, mental retardation, and a congenital
pseudobulbar syndrome. Schizencephaly, or gray matter lined clefts of the brain, occurs after disruption of the
RGF units from the ventricle to the pial surface. Smaller clefts may have coapted walls or closed lips. Larger clefts,
or those with open lips, may allow free communication of the ventricles with the pericerebral spaces. [4,5]
Figure 10. CT scan showing Subependymal nodular
heterotopia with cerebellar hypoplasia
Figure 11. MRI showing Subependymal nodular
heterotopia
Also included in disorders of cortical organization are cortical dysplasia without balloon cells, with imaging

9. features similar to the previously described focal cortical dysplasia with balloon cells, and microdysgenesis. Small
foci of cortical dysplasia may require serial imaging over time, becoming apparent only when myelin maturation is
complete. Other foci may be apparent only with high-resolution, high-contrast imaging, such as is possible with
GRE sequences. Microdysgenesis is radiographically undetectable with pathologic features consisting of subtle
neocortical abnormalities: neuronal ectopias within the white matter, abnormal neurons within the molecular layer,
neuronal clustering; bare areas within cortical layers two to six, and Chaslin's subpial gliosis. [6,17,31]
Figure 12. Lissencephaly Type 1. Tl -weighted (TR 600/ TE 15) (A) and
T2-weighted (TR 3000/TE 120) (B) coronal images in a severely delayed
patient with Miller-Dieker syndrome show a smooth cortical surface.
Thickened cortex with rare gyri along the inferior temporal lobes is seen
on Tl-weighted (C) and T2-weighted (D) coronal images in a patient
with agyria-pachygyria complex and seizures.
Figure 13. Bilateral opercular dysplasia is present in a 14-year-old with a history of spastic diplegia and recent
onset of seizures. Primitive Sylvian fissures lined by thickened cortex are seen on Tl -weighted (TR 600/TE 15) (A)
and T2-weighted (TR 2800/TE 90) (B) axial images.

10. Figure 14. Closed-lip schizencephaly is seen on the right, and a deep cleft
on the left on T1 -weighted (TR 600/TE 15) (A) and T2-weighted (TR
2800/TE 90) (B) axial images in a 2-year-old with psychomotor delay and
microcephaly. Open-lip schizencephaly is documented on Tl -weighted
(C) and T2-weighted (D) coronal views in a 2-year-old presenting with
spastic quadriparesis.
Figure 15. Open-lip schizencephaly with
cortical dysplasia

11. Figure 16. Bilateral open lip schizencephaly
SUMMARY
SUMMARY
Lissencephaly is the most severe of the disorders discussed in this case recport and the most easily diagnosed by
magnetic resonance imaging (MRI). In all types of lissencephaly the surface of the brain is abnormally smooth, with
shallow sulci and an abnormal gyral pattern. In some types of lissencephaly the gyri are also abnormally broad and
flat. lissencephaly can be divided by MRI criteria into five categories.
 Type I Lissencephaly
In type I lissencephaly, neuronal migration to the cortex has stopped before completion. Therefore, a band of
neurons lies in the subcortical region, separated from an abnormally thin cortex by a layer of white matter. The
cortex may be completely smooth (completely lissencephaly or agyria) or may have a few broad, flat gyri separated
by shallow sulci (pachygyria), a pattern that may be present in parts of otherwise completely lissencephalic brains.
Band heterotopias in which the cortex appears nearly normal have been arbitrarily included in a separate section in
this chapter. However, the reader should recognize that these are most likely a mild form of type I lissencephaly.
Depending on the severity of the lissencephaly, affected children may be microcephalic or normocephalic and may
range from profoundly retarded to nearly normal. Similarly, the neurologic findings and the occurrence of
associated anomalies vary with the severity of the migration defect.
On imaging studies, patients with type I lissencephaly have a smooth cortex that may be agyric, pachygyric, or
both, with an underlying layer of arrested neurons. The white matter is typically diminished in volume and the
Sylvian fissures are most commonly shallow and vertically oriented. The layer of white matter separating the cortex
from the layer of arrested neurons has a variable appearance depending on the severity of the lissencephaly and the
state of myelination, which are, in turn, dependent on the patient's age. Patients with severe lissencephaly have a
thick layer of white matter separating the cortex from the layer of arrested neurons, whereas those with milder
lissencephaly (mild pachygyria) have thinner layers of arrested neurons and thinner layers of white matter
separating the cortex from the arrested neurons. The gross appearance of the brain resembles that of the fetus
before 23 or 24 weeks of gestation, when sulci normally begin to form. The middle cerebral arteries typically lie
close to the inner table of the skull because there are no sulci in which they can lie. The severely affected cerebrum
has a figure-8 appearance on axial images as a result of the shallow vertical sylvian fissures. In severe agyria,
sagittal images may show a hypoplastic corpus callosum, with a small splenium and absent rostrum. The brainstem

12. often appears hypoplastic, probably because many of the corticospinal and corticobulbar tracts do not form. Areas
of pachygyria also have a thickened cortex, but broad gyri and shallow sulci are present. As stated earlier, the layer
of arrested neurons and the layer of white matter separating it from the cortex are thinner in pachygyric areas than
in agyric sections. Pachygyria can be focal or diffuse. When focal, it can occur in any part of the brain but is most
common, in my experience, in the parieto-occipital regions. When diffuse, it is often associated with regions of
agyria and tends to be more severe in the parieto-occipital region of the brain and least severe in the frontal and
temporal lobes.
 Type II Lissencephaly
Type 11 lissencephaly occurs in the Walker-Warburg syndrome and in Fukuyama's congenital muscular
dystrophy. It is characterized pathologically by lissencephaly, microphthalmia with retinal dysplasia, callosal
hypogenesis, cerebellar cortical dysplasia, cerebellar vermian hypoplasia, hypomyelination, and hydrocephalus,
which may result from obliteration of the subarachnoid spaces by thickened, fibrous meninges (3,11-14).
Histologically, the cortex is characterized by a lack of lamination and disruption by penetrating vessels and
fibroglial bundles that are continuous with the fibroglial tissue obliterating the subarachnoid spaces. The cortex is
thicker than normal but not as thick as the combined cortex, layer of white matter, and layer of arrested neurons of
type I lissencephaly.
MR imaging studies mirror the pathologic findings. The cortex is lissencephalic and thick, with an irregular gray-
white matter junction that probably represents the bundles of disorganized cortex surrounded by fibroglial tissue.
Ventricles are large, and the patient has often been shunted before CT or MRI scans are obtained. The corpus
callosum is hypogenetic or absent and the cerebellar vermis is always hypogenetic-hypoplastic with agenesis of the
inferior vermis. The white matter is almost completely unmyelinated. About half of patients have an occipital
encephalocele or evidence of a repaired encephalocele.
 Type III Lissencephaly (Microcephalia Vera)
The term "microcephalia vera" has been used to describe several genetic and sporadic developmental brain
anomalies. Patients typically present with microcephaly and moderate developmental delay but no focal neurologic
findings. Histopathologic examination of one brain of an affected 26-week gestational age fetus showed no
migratory disorder. However, the germinal zone was completely depleted at an age when the normal germinal zone
is of maximal volume.
Pathologic examination shows a thin cerebral, cortex, diminished cerebral white matter, shallow sulci, and
markedly diminished callosal axons. The only MR study published of a presumed case of microcephalia vera shows
a very small brain with complete lissencephaly and an extremely thin cortex. No layer of arrested neurons was
identified.
 Type IV Lissencephaly (Radial Microbrain)
The term "radial microbrain" has been used to describe patients born at term with markedly reduced brain size
despite normal gyral patterns, normal cortical thickness, normal cortical lamination, and absence of destruction or
gliosis (18). However, the number of neocortical neurons was only 30% of normal. All affected patients had
profound microcephaly and non-CNS anomalies, such as nephropathy and acromicria. We have performed MRI on
three infants that we believe fulfill the criteria for radial microbrain. All had profound microcephaly, delayed
myelination, and a slightly immature gyral pattern. We presume that the myelination delay is due to lack of
production of oligodendrocyte precursors by the depleted germinal zones.
 Type V Lissencephaly (Diffuse Polymicrogyria)
Diffuse polymicrogyria is a type of smooth brain that involves the entire cerebrum. Patients with this severe
condition typically are microcephalic and present with developmental delay or the onset of seizures in the first 6-8
months of postnatal life. In our experience, most patients with diffuse polymicrogyria have congenital
cytomegalovirus infections. MR images show a slightly thickened cortex (typically 5-7 mm) with irregularly
"bumpy" outer and inner surfaces. The ventricles are typically enlarged and the white matter hypomyelinated.
Patients with diffuse polymicrogyria are differentiated from those with Walker-Warburg syndrome by the absence
of callosal and ocular anomalies and by the "bumpy" outer cortical surface. The outer cortical surface in the
Walker- Warburg syndrome is typically smooth on MRI studies.
 Addendum

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REFERENCES
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