AIM: Brant: Ch 66: Pediatric Neuroradiology Flashcards
Meaning of ALARA
As Low As Reasonably Achievable
T/F: At least 20 separate radiographs are required for a skeletal survey for child abuse
True
T/F: One key difference between adult and pediatric fluoroscopic studies is that double-contrast GI studies are rarely performed in children who either cannot tolerate the distention or may not be able to maintain the gas.
True
Modality considered to be the workhorse of pediatric imaging
Ultrasound
At all ages, the ____ is probably the most important factor in obtaining high-quality images in ultrasound.
Ultrasound technologist
Myelination begins in the ____ fetal month and continues throughout life.
5th
In a normal infant, myelination appears complete on conventional T1-weighted images (T1WI) by around ____ months, on T2 weighted images (T2WI) by ____ months, and on FLAIR images by ____ months of age.
12, 24, 40
The fatty structure of lipoprotein causes T1 shortening wherever myelin is deposited, but the T2 hypointensity of myelin reflects the displacement of interstitial water by the progressive thickening of the myelin sheath on axons, and thus appears later.
We rely on T1WI for myelin evaluation in the ____ year of life and T2WI in the ____ year.
first, second
By what age the appearance of white matter myelination in T1 similar to that of an adult?
1 year of age
What fissure first develops, and at what age?
Sylvian fissure at 16-18 AOG
At what AOG do all primary and seconday sulci are formed?
34 weeks AOG
While the normal neonatal corpus callosum can appear quite thin, the splenium should be at least as thick as the ____ by 1 year of age.
Genu
The genu and splenium of the corpus callosum are myelinated by 6 months of age
Developmental abnormalities of the corpus callosum are referred to as ____, a spectrum that ranges from complete agenesis through partial agenesis to hypoplasia of the corpus callosum.
Dysgenesis of the corpus callosum
In complete agenesis of the corpus callosum, the lateral ventricles have a parallel orientation, with posterior dilation termed ____
Colpocephaly
In corpus callosum dysgenesis, the axons that would normally have crossed the midline instead line up in an anterior to posterior configuration along the medial aspect of each lateral ventricle; these tracts are called ____
Probst bundles
Give the sign and name the disease entity
Texas longhorn appearance of lateral ventricles in Corpus Callosum Agenesis (or Moose head appearance)
Diagnosis
Interhemispheric lipoma in Corpus Callosum Dysgenesis
T/F: Optic nerve hypoplasia is more reliably diagnosed on ophthalmologic examination, as only 50% of affected patients have appreciable optic nerve hypoplasia on MRI.
True
It encompasses a spectrum of malformations caused by abnormalities of differentiation and midline cleavage of the prosencephalon during the 5th gestational week.
Holoprosencephaly
Hallmark of holoprosencephaly
Abnormal communication of gray and/or white matter across midline
Facial dysmorphism is seen in up to 80% of cases and includes hypotelorism, cyclopia, ethmocephaly, cebocephaly, and midline cleft lip/palate.
Implies complete absence of cleavage with anterior displacement of the cerebra tissue into a “pancake” configuration and a large monoventricle that expands posteriorly into a dorsal cyst
Alobar holoprosencephaly
This structure can be partially present in lobar holoprosencephaly but not in alobar prosencephaly
Anterior falx cerebri
It is characterized by cerebellar tonsillar protrusion below the foramen magnum in the absence of an open spinal dysraphism or intracranial mass effect.
Chiari I
Cerebellar tonsillar protrusion is usually defined as tonsillar descent ≥5 mm below the McRae line which is the line drawn from the ____ to the ____
Basion to opisthion
The classic clinical presentation is an occipital headache induced or exacerbated by a Valsalva maneuver, but up to 14% of cases identified on imaging are asymptomatic.
What do you call this entity pointed by the white arrow?
Syrinx
Give 2 signs and diagnosis
Lemon sign and banana sign
Chiari II Malformation
The malformation can be identified on prenatal ultrasound by bifrontal concavity of the calvarium (“lemon” sign) and a flattened cerebellum wrapping around the brainstem (“banana sign”).
This malformation comprises a constellation of imaging findings in the brain associated with an open spinal dysraphism (either a myelomeningocele or myelocele).
Chiari II malformation
It is rare and is characterized by a cervico-occipital encephalocele containing posterior fossa contents
Chiari III malformation
This group of posterior fossa malformations includes a number of abnormalities characterized by varying degrees of vermian hypoplasia and malposition in association with posterior fossa cysts.
Dandy–Walker Continuum
In characterizing Dandy–Walker Continuum, the following structures are evaluated:
a. Posterior fossa
b. Vermis
c. Cisterna magna
d. All of the above
d. All of the above
The classic Dandy–Walker malformation is a triad of
Complete or partial agenesis of the vermis
Cystic dilation of fourth ventricle
Enlarged posterior fossa with upward displacement of the tentorium
An angiographic finding key to the diagnosis prior to the advent of cross-sectional imaging in classic Dandy-Walker malformation
Torcular-lambdoid inversion
The elevation of the tentorium places the torcula herophili above the lambdoid sutures, an angiographic finding key to the diagnosis prior to the advent of cross-sectional imaging, termed “torcular–lambdoid inversion.”
T/F: Obstructive hydrocephalus is a common complication and is a part of the dandy walker malformation itself
False
Obstructive hydrocephalus is a common complication but is not a part of the malformation itself
In the postnatal period the height of the vermis should be roughly equal to the distance between the ____ and ____
Midbrain tectum and obex
In Dandy–Walker variant, there is no enlargement of the posterior fossa coupled by a finding of a hypoplastic vermis that is often rotated counterclockwise such that the tegmento-vermian angle, formed by lines drawn along the brainstem and ventral vermis, is >____.
> 18 degrees
It is an embryonic structure that perforates in the first trimester to form the foramen of Magendie and foramina of Luschka
Blake pouch
This is the only entity in the DANDY–WALKER CONTINUUM where the tegmento-vermian angle is normal
Mega cisterna magna
This is the only entity in the DANDY–WALKER CONTINUUM where the posterior fossa is large
Classic Dandy-Walker Malformation
Blake pouch remnant can be considered normal up to what AOG?
20 weeks AOG
When the perforation of Blake pouch is delayed or incomplete, it can result in a ____ causing upward displacement of an otherwise normally formed cerebellar vermis. The vermis is normal in size and morphology in this entity, but the tegmento-vermian angle is increased.
Blake pouch remnant or cyst
It is a result of delayed fenestration of Blake pouch; it is defined as isolated enlargement of the cisterna magna with a normal tegmento-vermian angle and is considered a normal variant.
Mega cisterna magna
Cut off to consider enlargement of cisterna magna
> 10 mm
It is heterogeneous group of disorders mostly resulting from mutations of genes encoding ciliary proteins. Clinically these patients are described to have episodes of irregular breathing during infancy (“panting” or “laughing” respirations) with oculomotor apraxia.
Give the classic neuroimaging findings (2) seen below and the diagnosis
- Vermian hypoplasia
- Molar tooth sign
Joubert Syndrome and Related Disorders (JSRD)
Molar tooth sign: thickening and elongation of the superior cerebellar peduncles resemble the root of an extracted molar tooth on axial MR images
There can be hypoplasia or even absence of some of the lower brainstem nuclei. Additional associated anomalies include polydactyly, colobomas, and polycystic kidneys.
It is the incomplete separation of the cerebellar hemispheres in association with partial or complete absence of the vermis. MR imaging can uniquely demonstrate the transversely oriented continuous folia, and the flattened fastigial recess caused by at least partial absence of the cerebellar vermis.
Rhombencephalosynapsis
Up to 65% of these patients have coexisting aqueductal stenosis. Other associated syndromes include Gomez–Lopez-Hernandez syndrome and VACTERL.
It is the most severe manifestation of decreased cellular proliferation, in which there is nearcomplete absence of the sulci and gyri with marked microcephaly
Microlissencephaly
It is a milder phenotype where the brain is smaller than normal, with a reduced number of simple-appearing gyri
Microcephaly with simplified gyral pattern
The most extreme manifestation of increased cellular proliferation is ____, a hamartomatous overgrowth of part or all of a cerebral hemisphere.
Hemimegalencephaly
Unchecked proliferation and abnormal differentiation result in a bizarre appearance of the affected hemisphere, with a paradoxically enlarged lateral ventricle, thickened and ill- defined cortical ribbon, and mineralization and neuronal heterotopia causing the “white matter” to appear prematurely myelinated
A less dramatic and more localized increase in proliferation in association with abnormal cellular differentiation can result in ____, a leading cause of medically refractory epilepsy in children. These lesions can be very subtle on imaging, with focal cortical thickening, blurring of the gray–white matter junction, and a funnel-shaped white matter signal abnormality extending from the subcortical region toward the ventricle
Type II focal cortical dysplasia (FCDII)
It is the result of arrest of the radial migration of neurons from the germinal matrix along the walls of the ventricles to the developing cerebral cortex during the migrational phase.
Gray matter heterotopia
It is a genetically driven migrational arrest that typically appears as smooth symmetric bands of gray matter found between the ventricular surface and cerebral cortex. The overlying cortex is either normal or along the lissencephaly/pachygyria spectrum and nearly all affected patients are female
Band heterotopia
It is the result of arrested neuronal migration resulting in an abnormally thickened cortex and absence of the normal gyral–sulcal pattern.
Describe the sign/appearance, identify the pointed structure and give the diagnosis
Hour-glass appearance
Cell-sparse zone
Lissencephaly/Pachygyria
It results from abnormalities of late neuronal migration and cortical organization, causing an increased number of abnormally small gyri
Polymicrogyria
Most common location of polymicrogyria
Perisylvian
It is believed to reflect a prevention of neuronal migration from the germinal matrix outward, resulting in a transmantle cleft lined by dysplastic gray matter extending from the ependyma to the pial surface
Schizencephaly
Although neuronal migration continues to occur throughout gestation and beyond delivery, a majority occurs between ____.
12 and 24 weeks
Give the diagnosis and the artery that which was bilaterally obstructed to have resulted in this condition
Hyranencephaly
Internal carotid artery
What supplies the surviving brain the infants with hydranencephaly?
Posterior circulation and/or meningeal branches of the external carotid arteries
It is a distinct pattern of white matter injury that affects the developing brain, between 24 and 34 weeks of gestational age, caused by damage to oligodendrocyte precursor cells (preoligodendrocytes, oligodendrocyte progenitor cells [OPCs]).
It is a pattern of injury that is seen in many children diagnosed with cerebral palsy; symmetric loss of periventricular white matter surrounding the trigones of the lateral ventricles, with a characteristic angular morphology of the adjacent lateral ventricles as they expand into the vacated parenchyma
Periventricular leukomalacia
MR imaging will show punctate foci of abnormal hyperintensity in the periventricular white matter on T1WI
This injury can be recognized by transcranial US, where the injured white matter may appear abnormally hyperechoic
The ability of the brain to mount a reparative response to injury is markedly limited prior to 34 weeks of gestation; as a result there is little or no gliosis.
It represents a “watershed zone” of cerebral blood flow in the immature brain, with poor autoregulation
Periventricular white matter
This week AOG will determine whether or not gliosis shall be observed in PVL
34 weeks AOG
These are hereditary syndromes that are grouped together because they primarily affect structures of ectodermal origin, that is, the nervous system and skin.
Neurocutaneous disorders or phakomatoses
The most common of the phakomatoses
Neurofibromatosis type 1 (von Recklinghausen disease, NF-1)
Peripheral neurofibromatosis
Located on chromosome 17, the NF-1 gene codes for neurofibromin, which has numerous functions including tumor suppression, myelination, and neuronal and astrocytic development.
It usually develops multiple cutaneous lesions (café au lait spots, axillary freckling, cutaneous neurofibromas, and Lisch nodules) and for this reason, this NF was termed peripheral neurofibromatosis
NF-1
Per1pheral NF
Which NF has its nerve sheath tumors the potential for malignant degeneration?
NF-1
Aka central neurofibromatosis
NF-2
Bilateral vestibular schwannomas are diagnostic of this syndrome
It is an autosomal dominant disorder, characterized by dysplastic tumor-like lesions in the brain, lungs, skin, kidneys, and heart
Tuberous sclerosis
It is a consequence of failure of development of venous structures draining cerebral cortex, eye, and skin.
Sturge–Weber syndrome (encephalotrigeminal angiomatosis)
Face: cutaneous capillary malformation - port-wine nevus
Brain: pial angioma > chronic venous insufficiency and ischemia > subcortical calcifications, gyral atrophy and gliosis
Eye: choroidal hemangioma > glaucoma and exudative retinal detachment
Other features:
1. Primitive venous drainage (developmental venous anomalies [DVAs])
2. Ipsilateral choroid plexus hypertrophy is another feature of this entity
Name: Red arrow, white arrow, arrowhead
Give the diagnosis
Red: subcortical tubers
White: subependymal nodules
Arrowhead: Subependymal giant cell astrocytoma or “subependymal giant cell astrocytoma (SEGA)
It is an autosomal dominant disorder consisting of retinal, cerebellar and spinal hemangioblastomas. Other features include renal cell carcinoma, pheochromocytoma, cysts in the kidneys, liver, and pancreas. It typically manifests in the second and third decades.
von Hippel– Lindau syndrome (CNS angiomatosis)
Considered benign vascular neoplasm with characteristic features of a well-circumscribed cystic lesion with an enhancing mural nodule. A helpful finding suggesting the diagnosis is a large blood vessel leading to the enhancing nodule
Hemangioblastoma
Rarely the neural tube will successfully separate from the cutaneous ectoderm and close but a defect in the skin will persist, with a tract that descends into the subcutaneous tissues or spinal canal called a ____
Diagnosis:
Dorsal dermal sinus
Diagnosis: Infected dorsal derma sinus
It is characterized by agenesis of a portion of the caudal spine usually in association with spinal cord, anorectal and/or genitourinary anomalies.
Caudal agenesis or caudal regression syndrome
Group 1 vs Group 2 caudal regression syndrome:
a. Low-lying tethered cord and may have an additional closed spinal dysraphism such as an intradural lipoma or lipomyelomeningocele.
b. Have a high (L1 or higher) blunted conus with separation of the anterior and posterior nerve roots in a “double-bundle” configuration.
a. Group 2
b. Group 1
Group 1: HIGH
Group 2: LOW
In a process called neurulation, the neural ectoderm folds inward and forms a tube, with the center of the tube becoming the ____ and the central canal of the spinal cord.
Ventricles
Open spinal dysraphisms, sometimes categorized as ____
Spina bifida aperta
This type of spina bifida aperta has its neural placode projecting beyond the plane of the back the malformation
Myelomeningocele
This type of spina bifida aperta has its neural placode laying flat relative to the rest of the back
Myelocele
This lesion forms when interspersed mesodermal tissue prevents the normal development of the posterior bony elements and differentiates into fat, which is contiguous with the subcutaneous fat and tethers the cord at the site of the malformation:
a. If the placode projects beyond the posterior laminar line
b. If the placode does not project beyond the posterior laminar line
Diagnosis:
a. Lipomyelomeningocele
b. Lipomyelocele
Diagnosis: Lipomyelocele
If the mesodermal tissue completely separates from the overlying mesoderm, the posterior elements of the bony canal can close, and the result is an ____
Intradural lipoma
The major abnormality in ____ is a focal dilation of the central canal that causes the cord to protrude through a defect in the dorsal elements. Unlike other closed (skin-covered) spinal dysraphisms, this can be associated with hindbrain herniation.
Myelocystocele
Skin-covered lesions, myelocystoceles can occur in either, and are called:
a. Lumbar or lumbosacral
b. Cervical or thoracic spine
Diagnosis:
a. Terminal myelocystocele
b. Nonterminal myelocystocele
Diagnosis: Nonterminal myelocystocele
It is thought that the development of the neural plate and subsequent infolding to form the neural tube is induced by the ____, a streak of cells situated between the ectoderm and endoderm.
Notochord
If the notochord is divided, two separate neural tubes may form, resulting in two hemicords, called ____
Diastematomyelia or split cord malformation (SCM)
Type 1 vs Type 2 SCM:
a. Each hemicord with their own dural sac
b. Single dural sac
Diagnosis:
a. Type 1 SCM
b. Type 2 SCM
Diagnosis: Type 1 SCM
It is a clinical diagnosis based upon the constellation of pain, gait abnormalities, sensory disturbances, and/or lower extremity weakness, in association with a structural abnormality of the distal cord that could be a cause of increased tension or restricted mobility of the conus medullaris.
Diagnosis:
Tethered cord syndrome
Diagnosis: Fatty Filum Terminale With Tethered Cord
It is the term used to describe a cystic cavity within the spinal cord, usually representing the dilated central canal
Diagnosis:
Syringomyelia or syrinx
Diagnosis: Syringomyelia
The normal central canal is frequently visible on MR imaging, and diameters of up to ____ are likely of no significance.
3 mm
If a syrinx cavity is identified, careful review of the entire spinal column, with special attention to the craniocervical junction, is required.
Scoliosis is defined as any lateral spinal curvature ____.
> 10 degrees
Scoliosis:
a. Most frequent type, with female preponderance and typically presenting with a primary thoracolumbar curve convex to the right (dextroscoliosis).
b. Progression is most common in this type
a. Adolescent
b. Juvenile
In the term neonate, we should see T1 hyperintense myelin in the following structures, except:
a. Deep cerebellar white matter
b. Hippocampus
c. Dorsal brainstem
d. Posterior limbs of the internal capsules
b. Hippocampus
The genu and splenium of the corpus callosum are myelinated by ____ months of age
a. 3
b. 6
c. 9
d. 12
b. 6
What AOG does the fetal brain appear similar to that of a term infant?
a. 36
b. 37
c. 38
d. 39
c. 38
In the term neonate we should see T1 hyperintense myelin in the following structures, except:
a. Deep cerebellar white matter
b. Dorsal brainstem
c. Anterior limbs of the internal capsules
d. Posterior limbs of the internal capsules
c. Anterior limbs of the internal capsules
Ill-defined symmetric FLAIR hyperintensity in these regions (so-called “terminal zones of myelination”) reflects the greater concentration of interstitial fluid in these regions, and persists through the first several years of life.
a. Periaqueductal regions
b. Subthalamic regions
c. Peritrigonal regions
d. Perivascuscular regions
c. Peritrigonal regions
The following findings are suggestive of complete corpus callosum agenesis, except:
a. Colpocephaly
b. Upturned posterior horns of the lateral ventricles
c. Absence of the cingulate sulcus allows the interhemispheric sulci to extend all the way to the third ventricular margin
d. Underrotated hippocampi
b. Upturned posterior horns of the lateral ventricles
ANTERIOR
The following findings can be seen associated with partial agenesis or hypogenesis of the corpus callosum, except:
a. Truncation of the anterior–posterior dimension, though it can also be segmental, with the callosum appearing as two separate commissures
b. Interhemispheric cysts
c. Interhemispheric lipomas
d. All of the above are associated with partial agenesis or hypogenesis of the corpus callosum
d. All of the above are associated with partial agenesis or hypogenesis of the corpus callosum
Diagnosis
Corpus callosal lipoma
The following are associated with optic nerve hypoplasia, except:
a. Partial or complete absence of the septum pellucidum
b. Dysgenesis of the corpus callosum
c. Anomalies of the hypothalamic–pituitary axis
d. Malformations of cortical development, most notably schizencephaly
e. AOTA are associated with optic nerve hypoplasia
e. AOTA are associated with optic nerve hypoplasia
In this malformation, there is lack of separation of the posterior frontal and parietal regions with cleavage of the anterior frontal and occipital lobes
Syntelencephaly
Associated findings in Chiari I malformation include the following, except:
a. Abnormal pointed morphology of the cerebellar tonsils
b. Ventral tilt of the dens
c. Basilar invagination and platybasia
d. Effacement of the CSF spaces at the foramen magnum
b. Ventral tilt of the dens
DORSAL
This associated finding in Chiari I malformation is deemed important as this is one of the main causes of neurologic deficits and symptoms
a. Syringomyelia
b. Basilar invagination
c. Platybasia
d. Effacement of the CSF spaces at the foramen magnum
a. Syringomyelia
Diagnosis
Syringomyelia/syrinx
Diagnosis
Chiari II malformation
Diagnosis
Classic Dandy-Walker malformation
Injuries occurring prior to ____ weeks of gestation that disrupt neuronal migration often result in fetal demise or severe global brain malformations
a. 6 weeks
b. 12 weeks
c. 24 weeks
d. 36 weeks
c. 24 weeks
In more severe hypoxic/ischemic injury, a primary factor in the pattern and propagation of injury is the presence of excitatory synapses that rely on the neurotransmitter glutamate and are populated by N-methyl-d-aspartate (NMDA) receptors. These receptors are overexpressed in the developing brain and are concentrated in the following locations, except:
a. Thalami
b. Subthalamic nuclei
c. Brainstem
d. None of the above
c. Basal ganglia
Normally hand preference should not be evident prior to ____ of age
a. 12 months
b. 18 months
c. 24 months
d. 26 months
b. 18 months
True about NF-2, except:
a. It is more common in young adult and affects chromosome 22
b. CNS findings include T2 hyperintensities in the basal ganglia, thalami, deep cerebral white matter and cerebellum
c. Malignant degeneration of nerve sheath tumors are rare
d. Sphenoid dysplasia, ribbon ribs, and vascular dysplasias are uncommon
b. CNS findings include T2 hyperintensities in the basal ganglia, thalami, deep cerebral white matter and cerebellum
These are seen more in NF-1 and do not exhibit mass effect or enhancement, and they may overlap gray and white matter structures. They are dynamic, typically absent in young infants, increasing in frequency until around age 10, decreasing after puberty, and rarely seen in adulthood. On pathology they are characterized by spongiform changes due to abnormal myelin vacuolization, and their subsequent resolution is presumed due to myelin repair. Although benign in and of themselves, they can make identification of adjacent neoplastic lesions more difficult.
Most common optic nerve glioma in NF-1
Pilocytic astrocytoma
Indolent with asymptomatic tumors
MRI: fusiform enlargement of the optic nerves with variable enhancement, and extension to optic chiasm and may also spread dorsally into the optic tracts and adjacent brain
True about peripheral tubers:
a. They’re usually visualized as cortical–subcortical dysplastic lesions that may or may not enhance
b. Once myelination is completed, these lesions are best visualized on T2-weighted sequences, where they are hyperintense relative to normal white matter
c. With time the subcortical component may become cystic, and some lesions may develop calcifications
d. All of the above
d. AOTA
Which among the findings are most characteristic brain lesions in patients with tuberous sclerosis:
a. Peripheral tubers
b. Subependymal nodules
c. Subependymal giant cell astrocytomas
d. Gliomas of the retina
b. Subependymal nodules
-protrude inward from the outer walls of the lateral ventricles
-hyperintense on T1WI and hypointense on T2WI in infants, but become more isointense to white matter with age
-begin to calcify after the first year of life, and show variable enhancement
Other less common CNS manifestation of TS:
1. Curvilinear white matter lesions that extend from the ventricular margin toward the peripheral tubers, reflecting tracts of disordered neuronal migration caused by the mutation of the tuberin gene
2. Benign gliomas of the retina (giant optic drusen or retinal astrocytoma)
3. Giant aneurysms
These represent SEN near the caudothalamic groove that may develop proliferation of the balloon cells
Subependymal giant cell astrocytomas (SEGA)
-can enlarge to obstruct the foramen of Monro and cause hydrocephalus
-This is why evaluation for developing SEGAs is the primary reason for imaging follow-up in patients with TS
Diagnosis
Tuberous sclerosis
