Neonatal Head Pathology: Congenital and Acquired Developmental Problems

Terms in this set (59)

Congenital anomalies of the neonatal brain
number of different anomalies can occur in fetal brain development
agenesis of corpus callosum, Arnold-Chiari II Malformation, cephaloceles, Dandy-Walker Malformation, Dandy-Walker variant, holoprosencephaly, Hydranencephaly, lissencephaly, lipoma of corpus callosum, microcephaly, papilloma of choroid plexus, porencephaly, schizzencephaly, and septooptic dysplasia
Agenesis of corpus callosum
insult that occurs early in gestation: between 8 and 18 weeks
condition in which the fibers of the corpus callosum have not formed: either partial or complete
can be isolated anomaly w/o any clinical effect
commonly associated with other anomalies such as: Arnold-Chiari II, Dandy-Walker malformation, microcephaly, holoprosencephaly, lipomas, arachnoid cyst, migrational abnormalities, aqueductal stenosis, septooptic dysplasia, and porencephaly
UA: widely separated and slit-like lateral ventricles (bat-wing appearance), concave medial borders of lateral ventricles, absence of CSP, third ventricle dilated and elevated, enlargement of atria and occipital horns of lateral ventricles (colpocephaly), medial sulci radiate vertically above third ventricle (sunburst sign)
Chiari malformation
congenital anomaly associated with spina bifida
cerebellum and brainstem are pulled toward spinal cord and secondary hydrocephalus develops
Chiari Malformation type I
downward displacement of cerebellar tonsils w/o displacement of fourth ventricle or medulla
most common of all types
typically found incidentially on CT
best prognosis
Chiari malformation type II
elongation and caudal displacement of brainstem and cerebellum through foramen magnum into cervical spinal canal
can be seen prenatally on ultrasound: cerebellum is deformed (banana sign), frontal bossing (frontal bones are more beaked/pointed), high associations of myelomeningocele and hydrocephalus
UA: bat-wing configuration of frontal horns of lateral ventricles, partial or complete absence of CSP, colpocephaly, enlargement of massa intermedia (dilatation of third ventricle due to aqueductal stenosis), displacement of fourth ventricle, pons, medulla, and vermis, nonvisualization of fourth ventricle, small posterior fossa, possible hydrocephalus, and possible widening of intrahemispheric fissure
Chiari malformation type III
high cervical encephalomeningocele in which medulla, cerebellum, and fourth ventricle reside
Chiari malformation type IV
severe hypoplasia of cerebellum w/o displacement
Cephalocele
herniation of portion of neural tube through midline defect
usually located occipitally: can be located in nasal region
amount of brain tissue in defect varies: amount affects surgical treatment and survival
usually lateral ventricles are involved
Encephalocele
herniation of meninges and brain tissue
Encephalocystomeningocele
herniation of meninges, brain, and ventricles
Chiari III malformation: high cervical encephalomeningocele in which medulla, cerebellum, and fourth ventricle reside
Dandy-Walker malformation
dilation of fourth ventricle due to: trapped fourth ventricle due to occlusion of aqueduct of Sylvius, foramen of Magendie, and foramen of Luschka and disturbance in growth of roof of fourth ventricle
UA: large fluid-filled posterior fossa cyst, dilated fourth ventricle, absent cerebellar vermis, small cerebellar hemispheres, and superior elevation of tentorium and hydrocephalus
associated anomalies: encephalocele, agenesis of corpus callosum, gyral anomalies, holoprosencephaly, cleft palate, polysyndactylism, trisomies 13, 18, and 21, heterotopias, GI and GU anomalies, cardiac anomalies, congenital diaphragmatic hernia, and cystic hygromas
Dandy-Walker variant
milder abnormality of posterior fossa
enlarged cisterna magna that communicates that communicates w/ fourth ventricle w/normal or hypoplastic cerebellar vermis
hydrocephalus is usually absent
UA: large posterior fossa cyst that communicates w/ fourth ventricle, enlarged posterior fossa, elevation of tentorium, small brainstem, hypoplastic or absent cerebellar vermis, and absent CC
Subarachnoid cysts
cysts that are lined by arachnoid tissue and contain CSF
major causes: localized entrapment of fluid during development, residual subdural hematoma, and fluid extravasation (ventricular rupture)
UA: cyst that doesn't communicate w/fourth ventricle and may displace or compress fourth ventricle, cerebellum or brainstem
Mega cisterna magna
normal variant
normal fourth ventricle, cerebellum, and brainstem
shows no mass effect
may be confused w/Dandy-Walker malformation
measures greater than 8 mm
Holoprosencephaly
midline malformation resulting from failure of cleavage of prosencephalon into separate hemispheres
3 types: alobar, semilobar, and lobar
Alobar holoprosencephaly
brain surrounds single mid-line crescent shaped ventricle
thalami and hemispheres are fused
absent falx, CC, third ventricle, and interhemispheric fissure
facial defects: cebocephaly, cyclopia, and ethmocephaly
Cebocephaly
flat rudimentary nose
hypotelorism
single nostril
Semilobar holoprosencephaly
single midline ventricle w/increase in thickness of brain parenchyma
posterior portion of falx and intrahemispheric fissure may be present
absent or incomplete CC
partial separation of thalami
partial separation of single ventricle into occipital and temporal horns
less severe facial abnormalities: mild hypotelorism and median or lateral cleft lip/palate
Lobar holoprosencephaly
least severe
two separate hemispheres
slightly dilated lateral ventricles
absence of CSP
possible absence of cerebellar vermis
partial absence of CC
mild facial anomalies
Hydranencephaly
occlusion of the ICAs of fetus
causes necrosis of cerebral hemispheres
can also be caused by infection
characteristics: absence of both cerebral hemispheres, preservation of falx, thalamus, brainstem, cerebellum, and portions of occipital or temporal lobes
UA: large fluid filled cranial fault, falx, absence of internal carotid circulation, and intact cerebellum and midbrain
Lissencephaly
failure of development of sulci and gyri
known as smooth brain, agyria, or pachygyria
UA: absence of convolutional markings, moderate dilatation of lateral and third ventricles, absent pulsations in MCA in Sylvian fissure, and lack of normal interdigitation of gray and white matter
Microcephaly
small cranial vault due to brain atrophy
related to TORCH and genetic anomalies
UA: ventricles may be enlarged and calcifications may be seen in brain parenchyma or around ventricles
Porencephaly
etiology: infarct causes destruction of brain parenchyma and this forms a cavitation or CSF containing cyst that communicates w/ventricle
causes: infection, birth trauma, ventricular puncture, hypoxic-ischemic insult, and periventricular hemorrhage
UA: single or multiple cysts that communicate with ventricle and no mass effect
Schizencephaly
form of porencephaly: results in bilateral clefts in cerebrum
may be related to primary maldevelopment or vascular occlusion
UA: unilateral or bilateral symmetrical areas of cystic necrosis and extend from lateral ventricle through entire hemisphere
Septooptic dysplasia
also known as Morsier syndrome
congenital underdevelopment of optic nerve
malformation of anterior midline structures: agenesis of CC and dilated and flattened lateral ventricles
Intracranial masses
midline displacement
mass or lesion alters relationship of brain anatomy
solid masses may cause midline displacement
solid masses: rare
supratentorial are more common than infratentorial
effects include: obstruction of ventricular outflow, ventriculomegaly, and hydrocephaly
UA: varied and nonspecific and most are hyperechoic
Teratomas
most frequent type of solid mass (50%)
clinical signs: increase in HC, increase in intracranial pressure
UA: large, echogenic with cystic spaces, and calcifications causing acoustic shadowing
Glioma
brain stem, optic pathway, and hypothalamic
Lipoma of CC
associated w/agenesis of CC
echogenic mass w/possible calcifications seen in CC
may cause frontal horns of lateral ventricles to be widely separated and tapered
Papilloma of choroid plexus
epithelial tumor found in choroid plexus
usually unilateral and benign
may cause an increase in CSF secretion or obstruction of CSF flow
head may rapidly increase in size due to hydrocephalus
UA: echogenic mass with dilated ventricle and may compress adjacent structures
Types of intracranial masses
astrocytoma, epidermoid tumors, metastatic lesions, inflammatory cysts (subdural empyema and abscess), hemorrhage/hematoma
Hemorrhage/hematoma
UA: acute (echogenic mass effect), subacute (center of hematoma is hypoechoic, outer rim is echogenic), 2-3 months after bleed (hematoma will be completely cystic due to necrosis and may develop porencephalic cyst)
Acute meningitis
bacterial is most common cause
causes inflammation of arachnoid and pia membranes: hyperemia of meningeal vessels
UA: normal appearing brain, extra-axial fluid collections, ventriculomegaly (obstruction of CSF outflow), increased parenchymal echogenicity (focal or diffuse), and widened echogenic sulci
Cerebritis
inflammation of brain parenchyma
possible complication of meningitis
diffuse or patchy areas of parenchymal echogenicity
increased echogenicity of gyra
decreased vascular pulsations
Abscess
uncommon complication of meningitis
Ventriculitis
complication of meningitis (60-95%) of cases
ventricles at be slit-like (acute phase)
irregular choroid plexus
thickened irregular ependyma
intraventricular septations
Multicystic encephalomalacia or white matter necrosis (WMN)
possible end result of meningoencephalitis or due to brain ischemia
anechoic areas of cystic degeneration are noted in echogenic parenchyma
TORCH
toxoplasmosis, other (syphilis), rubella, CMV, Herpes simplex 2
fetal infections that are acquired through placenta
Toxoplasmosis
earlier it is transmitted in utero, the more severe the neurological damage
UA: cortical and periventricular calcifications, hydrocephalus, cerebral atrophy, microcephaly, and porencephaly
Rubella
UA: scattered calcifications, microcephaly, ventriculomegaly, and ischemic necrosis
Cytomegalovirus (CMV)
most common congenital infection
results in severe damage to developing brain
earlier exposure leads to more severe damage
UA: hypoplastic cerebellum, periventricular calcifications, and lissencephaly
Herpes simplex 2
UA: Multicystic encephalomalacia, cerebellar involvement, punctate calcification, and cerebral atrophy or edema
Brain swelling
commonly associated with hypoxic-ischemic events
secondary to birth asphyxia
could result in PVL
UA: slit-like ventricles, poorly defined sulci, diffusely echogenic brain, loss of anatomical landmarks, and snowstorm speckling appearance
Doppler characteristics of cerebral edema
initially with brain ischemic, flow in brain increases: prior to significant cerebral edema, attempt to increase cerebral perfusion, diastolic flow will rise, causing a lower than normal RI (<0.6) normal is 0.7
as cerebral edema increases, RI will also increase (diastolic flow increases) : result of edema pinching the vessels
Atrophy of brain
loss of brain cells: can be focal affecting an area of brain or it can be diffuse which can cause overall decrease in brain size
congenital: Hydranencephaly, TORCH infection, porencephaly, and ventriculomegaly
acquired: CMV acquired after birth, longstanding hydrocephalus or ventriculomegaly, porencephaly, and result of hypoxic-ischemic event (infarction, periventricular leukomalacia, and ECMO)
Infarction
leads to brain volume loss
secondary ventriculomegaly
normal to small head circumference
Periventricular leukomalacia (PVL)
most frequent hypoxic/ischemic lesion
found in 20-80% of neonatal autopsies
associated w/abnormal neurologic development
caused by coagulation necrosis in deep and periventricular white matter
usually found adjacent to lateral wall of frontal horns, body, atria, and occipital horns of lateral ventricles: areas of increased echogenicity (becomes cystic with loss of cerebral tissue and swiss cheese like appearance of parenchyma)
severe can eventually evolve into cystic encephalomalacia (softening of brain) and porencephaly: leads to seizures and cognitive disorders
Extracorporeal membrane oxygenation (ECMO)
heart-lung machine
used to treat infants w/severe respiratory failure: not responded well to ventilation
infants w/persistent fetal circulation or diaphragmatic hernia: rest the lungs while infant recovers to lung capacity
cannulas are inserted into vessels on RT side: remove venous blood and return oxygenated blood, RT ICA and IJV are permanently tied off for this procedure, and arterial blood is shunted from LT ICA through ACoA to supply RT MCA
complications: intracerebral and cerebellar hemorrhages, hypoxic brain damage secondary to lung disease, other causes included heparization and transient hypertension, and indicated termination of therapy
Persistent fluid-filled spaces
common finding in healthy neonates
fluid can be found in: CSP, cavum vergae, and cavum veli interpositi
most of these spaces close at 6 months GA: 85% of CSP close at 3-6 months post birth
if there is fluid in CVI, don't confuse this for vein of Galen malformation and pineal region cyst
if there is hydrocephalus present, don't measure CSP w/ventricular measurement
these persistent fluid spaces can persist into adulthood: normal variant of no significance
Immature sulcation in premature infants
normal infant brain goes through sulcation from 24-40 weeks GA: brain is relatively smooth before this time
if infant is born before this tie, the brain may appear abnormally smooth
do not want to confuse this w/lissencephaly
Asymmetric ventricular size
can be seen in 20-40% of infants
visualized as slight enlargement of LT vs. RT ventricle: LT is often larger than RT and can be dependent on patient position
make sure to rule this out vs. pathology: ventriculomegaly and colpocephaly
Colpocephaly
asymmetry between occipital and frontal horns
Choroid plexus locations
found along roof of 3rd ventricle
extends up through foramen of Monro to lateral ventricles: is not found in frontal or occipital horns
choroid is also found in fourth ventricle
if echogenic material is found in locations where choroid plexus exists, one should suspect a bleed
variations in choroid plexus shape: common and shouldn't be mistaken for hemorrhage and can occur at glomus of choroid plexus
Choroid cysts
smaller than 1 cm are noted in 1% of infants
typically nonspecific
no clinical significance
if they are multiple, bilateral, larger than 1 cm, they can be associated w/chromosomal anomalies
Cystic lesions seen near periventricular region
connatal cysts
subependyal cysts
white matter cysts associated w/ PVL
Connatal cysts
normal variant
typically regress spontaneously
located adjacent to frontal horns anterior to foramen of Monro: string of pearls type appearance
should be distinguished from other types of cysts
Germinal matrix cysts
associated w/ GMH
White matter cysts
associated w/PVL
Hyperechoic white matter pseudolesion or periventricular halo artifact
artifacts due to anisotropic effect
artifact can be seen adjacent to lateral ventricles: more prominent in premature vs. term infants
by turning 90 degrees will resolve this artifact: if it does not go away try approaching area using different angles and if it sill persists start thinking PVL
remember that there is normally a nice periventricular blush: normal blush is slightly less echogenic than artifact
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