Congenital malformations Flashcards
What are the spectrum of causes of aqueductal stenosis?
What are the associations?
Congenital narrowing of the aqueduct
Postinflammatory changes (post meningitis or hemorrhage)
Tumors
Chairi I/II, Dandy walker
What is the appearance of aqueductal stenosis?
What physiologic dysfunction can be seen?
Thickened tectum can be seen
Will see narrowing of the aqueduct
Endocrine dysfunction in 20% due to compression of hypothalamus-pituitary axis
What age group for type I chiari?
What is the etiology?
What distance for diagnosis? What else needed for diagnosis?
Adults
Mesenchymal malformation of craniocervical junction leading to hypoplasia of bones and dura
> 6cm is Dx, 3-6cm is tonsillar herniation
Need downward “pointing” tonsils for dx in indeterminate cases
What are the symptoms with chiari I malformation?
What is the treatment?
Headache, neck pain, nystagamus, lower CN palsy, basilar invagination, odontoid defromities, scoliosis, spinal cord cysts
Klippel-feil
Tx: resection of the hypoplastic posterior arch of C1, dural resection with duroplasty and recreation of cisterna magna
Cervical spinal cord cyst should trigger search for what malformation?
Chiari I
What is always associated with chiari II?
What is the cause?
Myelomeningocele
Chronic CSF leak in utero causes collapse of developing brain
What is are the skull and dura anomalies with chiari II?
Lacunar skull, scalloped petrous ridge and clivus, large foramen magnum, insufficient tentorial incisura, hypoplastic or fenestrated falx
What are the brain anomalies with chiari II?
Inferiorly displaced vermis into the foramen magnum
heart shaped cerebellum displaced superiorly through insufficient tentorial incisura, lack of cerebellar sulcation
Absent aqueduct
Beaked tectum
Callosal agenesis, large massa intermedia
Interdigitation of cortical sulci in superior midline
Hydrocephalus and colpocephaly (dilated atria and occipital horns)
Heart shaped cerebellum suggests what?
Chiari II
What is the geographic breakdown of encephalocele?
NA?
LAtin america/asia?
North america - occipital (80%), parietal (10%)
LA/Asia - syncipital (frontoethmoidal)
What is chiari III malformation?
Chiari II with low occipital/high cervical encephalocele
What is an atretic parietal meningocele?
Form fruste of encephalocele
Small amount of meninges, gliotic brain and CSF can cross the superior sagittal sinus and associated with venous anomalies( persistent falcine sinus)
What are the two syndromes associated with occipital/parietal encephaloceles?
Chiari III
Dandy walker
Who gets sincipital encephaloceles (anterior nasal)? What is always associated?
Which is more common - nasofrontal or nasoethmoidal
Latin american/Asian boys
hypertelorism
nasofrontal
What is the differential diagnosis of anterior encephalocele?
nasal glioma (brain heterotopia) and nasal dermoids
What is a nasal glioma
ISOLATED mass of brain tissue trapped in prenasal space
can grow
will enhance
What is a nasal dermoid?
may from anywhere from the tip of the nose to the nasal bones
Fatty appearance
Communicate with foramen cecum in front of a wide or bifid crista galli
What is seen in dandy walker syndrome?
obstruction of the outlet foramina of the fourth ventricle which becomes dilated
Large posterior fossa with high insertion of the torcula herophilli
Hydrocephalus
Inferior vermian hypoplasia
corpus callosal agenesis
What is the spectrum of dandy walker?
Mega cisterna magna - intact vermis, normal 4th ventricle, scalloping of inner table of bone
Variant - mild inferior vermian hypoplasia, enlarged vallecula that communicates with a mildly enlarged and keyhole shaped 4th ventricel and hydrocephalus
Full on disease
What is joubert syndrome?
Ataxia, hyperpnea, apnea, seizures, abnormal eye movements, mental retardation, motor apraxia, hypotonia
What is seen in joubert syndrome on imaging?
Hypoplastic/aplastic cerebellar vermis
Abnormal tracts in brainstem
Lack of decussation of superior cerebellar peduncles, which become thin and parallel
What is the molar tooth appearance? What is it seen with?
Superior cerebellar peduncles become thin and parallel
Joubert
What is holoprosencephaly? What are the types?
midline cleavage of the face and a failure of the diverticulation of the brain
Alobar
Semilobar
Lobar
Midline
Which types of holoprosencephaly have hypotelorism and facial midline clefts
alobar and semilobar
What corpus callosal abnormality is seen with holoprosencephaly?
Agenesis of the anterior aspect
What is the most severe type of holoprosencephaly? What is seen?
Alobar
monoventricle, absent septum pellucidum
falx cerebri and interhemispheric fissue are also absent
fused thalami
What is seen with semilobar holoprosencephaly?
Monoventricle with rudimentary occipital and temporal horns
absent septum pellucidum
thalami are fused
What is seen with lobar holopsrocencephaly?
Mild, lateral ventricles are almost normal but frontal horns point inferiorly
absent septum pellucidum
no thalamic fusion
indistinguishable from septooptic dysplasia
can have a solitary anterior cerebral artery
What is seen with midline holoprosencephaly?
Grey matter cleft extending through both hemispheres
fused frontal lobes
mid portion corpus callosum is absent
How does the corpus callosum form? how does it myelinate
Forms anterior to posterior
Myelinates posterior to anterior
What is also seen with a complete callosal agenesis?
absent cingulate gyrus and sulcus, high riding third ventricle
rostral interhemispheric arachnoid cyst
colpocephaly (dilation of atria and occipital horns of lateral ventricles)
can have isolated dilation of the temporal horns of the lateral ventricles
hippocampal malrotations
What are the associated anomalies with dysgenesis of the corpus callosum?
Chiari II Dandy walker Holoprosencephaly Interhemispheric lipoma Migration anomalies Azygous anterior cerebral artery Abnormalities of the optic chiasm and pituitary gland
What is septo-optic dysplasia? What is it indistinguishable from?
Absent septum pellucidum
Hypoplastic anterior optic pathways (chiasm and nerves)
Flat roof of lateral ventricles
Inferiorly pointed frontal horns
Lobar holoprosencephaly
What are the associations with septo optic dysplasia?
Maternal diabetes Quinidine ingestion Antiseizure medication Drug abuse CMV Chiari II/aqueductal stenosis
What is meant by the term septo optic dysplasia plus?
Septo optic dysplasia
schizencephaly
remnant septum pellucidum and normal visual apparatus
What physiologic abnormality is seen with septo optic dysplasia?
Endocrine dysfunction secondary to hypoplastic pituitary
Ectopic pituitary bright spot should prompt a search from what?
Septo optic dysplasia
What is a schizencephaly?
Transcerebral cleft (extending from cortex to ventricle) lined by abnormal gray matter - some have overlying CSF-filled cyst that may grow
What are the types of schizencephaly?
Open lip - contain CSF in cleft
Closed lip - walls of cleft are in apposition
What are the associated findings in schizencephaly?
Malrotated hippocampi
Absent septum pellucidum
Septo optic dysplasia
What are the symptoms with schizecephaly? Which type gets symptoms?
Seizures and hemiparesis
Open lip
What is lissencephaly? What is the imaging?
smooth brain with no sulcations
Thick grey matter with insufficient neurons, shallow sylvian fissures, lack of sulci, colpocephaly
What are the syndromes with lissencephaly?
Miller-dieker
Walker-warburg
Fukuyama
What is the double cortex sign?
What sex is it seen in?
Band heterotopia seen with lissencephaly
band o grey matter between subcortical and periventricular white matter
seen in females
What is the differential for nodular foci of grey matter along the ependymal surface?
Tuberous sclerosis
Grey matter heterotopia
What is the imaging of grey matter heterotopia?
Do not enhance, follow grey matter on all sequencing
What is cortical dysplasia?
Nonlissencephalic cortical dysplasia/Polymicrogyria
Smooth argyric grey matter
can have anomalous venous drainage
What is the cause of cortical dysplasia? Where do they occur usually?
Ischemia or CMV
MCA distribution
Which synostosis is more common in boys? females?
F - coronal
M - sagittal
What is the classification of synostosis?
Simple - one suture r part of it
Compound - more than one suture, may be syndromic
Bony/cartilaginous
What is the normal time period for closure of sutures? posterior fontanelle? anterior?
18-24 months (metopic 6-9 months)
2 months
Anterior - 7-9 months
