neuroradiology Flashcards
Describe the transmantle sign and its diagnosis
High T2/FLAIR signal extending from the ventricle to the cortex. Seen in focal cortical dysplasia, almost always type 2.
joubert syndrome CNS findings and extra-CNS associations
CNS findings:
bat wing 4th ventricle - elongated appearance of 4th ventricle resembles bat with wings outstretched. due to absent vermis and apposed cerebellar hemispheres
molar tooth sign - elongated superior cerebellar peduncles give the midbrain a molar tooth appearance. Results from lack of normal decussation of superior cerebellar peduncular fiber tracts.
Small dysplastic or aplastic cerebellar vermis
Abnormal inferior olivary nucleus
Dysplasia and heterotopia of cerebellar nuclei
Associations:
coloboma retinal dysplasia (50%) nephronopthisis multicystic dysplastic kidneys (30%) hepatic fibrosis polydactyly (15%)
What is Ddx of cerebral ring enhancing lesions? (Mnemonic)
DR MAGIC L
D: demyelinating disease R: radiation necrosis or resolving haematoma M: metastasis A: abscess G: glioblastoma I: infarct (subacute phase) C: contusion L: lymphoma
Name the syndrome:
supranuclear vertical gaze disturbance cause by compression of the tectal plate.
Parinaud syndrome (dorsal midbrain syndrome)
most frequently due to a posterior commissure or pineal region mass
Contents of internal auditory canal
Facial nerve
Three components of the vestibulocochlear nerve:
Cochlear nerve
Superior vestibular nerve
Inferior vestibular nerve
Labyrinthine artery
Contents of foramen spinosum (3)
Middle meningeal artery
Middle meningeal vein
Meningeal branch of mandibular nerve
Key imaging feature of Chiari 2 malformation?
Extension of cerebellar tonsils/brainstem with small posterior fossa and myelomeningocele
What are the CNS imaging manifestations of NF1?
FASI: focal areas of signal intensity in deep white matter and basal ganglia or corpus callosum, areas of T2/FLAIR hyperintensity with no contrast enhancement
optic nerve glioma or optic pathway glioma (may manifest as enlarged optic foramen)
progressive sphenoid wing dysplasia
lambdoid suture defects
dural calcification at vertex
moya moya phenomenon (rare)
buphthalmos
Key imaging feature of Chiari 2 malformation?
Extension of cerebellar tonsils/brainstem with small posterior fossa and myelomeningocele
Describe the different types of focal cortical dysplasia (Blumcke classification)
Type I: focal cortical dysplasia with abnormal cortical lamination
a: radial cortical lamination
b: tangential 6-layer cortical lamination
c: radial and tangential cortical lamination
Type II: focal cortical dysplasia with dysmorphic neurons
a: without balloon cells
b: with balloon cells
Type III: architectural distortion of cortical layer
a: in temporal lobe with hippocampal atrophy
b: adjacent to glial or glioneuronal tumor
c: adjacent to vascular malformation
d: adjacent to other lesions acquired in early childhood
What are the MRI findings in limbic encephalitis
Most cases may not have positive imaging findings
Typical findings:
Bilateral (60%) medial temporal lobe and limbic system involvement.
Cortical thickening and hyperT2/FLAIR in these regions.
Patchy enhancement.
Diffusion restriction is uncommon (unlike herpes encephalitis)
What is the boundary between:
the parietal and temporal lobes the parietal/temporal and the occipital lobes?
The boundary between the parietal and temporal lobes lies on a line extended back from the lateral sulcus.
The parieto-occipital sulcus seperates parietal and occipital lobes however it is only present on the medial surface. On the lateral surface, the parietal/temporal lobes are seperated from the occipital lobe by a line between the superior border of the parieto-occipital sulcus and the preoccipital notch
Where is Broca’s area located?
In the pars opercularis and pars triangularis of the inferior frontal gyrus of the dominant hemisphere.
Brodmann 44 and 45
Where is the cingulate gyrus located (and what seperates it from adjacent structure)?
The cingulate gyrus extends along the medial surface of the frontal to parietal lobes.
It is seperated from the corpus callosum by the callosal sulcus and from the medial surface of the frontal/parietal lobes by the cingulate sulcus
What are the structures of the mesial temporal lobe? (5)
amygdala hippocampus uncus dentate gyrus parahippocampal gyrus
True or false: The normal pineal gland enhances post contrast administration
True
It does not have a blood-brain barrier.
What is the normal thickness of the pituitary infundibulum?
Up to 3.8mm at the optic chiasm
Up to 2.7mm at the pituitary gland
What is the differential diagnosis of subependymal nodules? (4)
Tuberous sclerosis
Heterotopic gray matter
TORCH infection
Metastatic disease
What are MR characteristics of cortical tubers?
Prior to myelination:
T1 hyperintense
After myelination:
Variable T1
T2 hyper
What is PML?
Progressive multifocal leukoencephalopathy
Demyelinating disease which occurs due to the JC virus infecting oligodendrocytes.
Strongly associated with immunocompromised states.
What are the MR findings of PML?
Bilateral asymmetric periventricular andsubcortical multifocal demyelination.
U-fibers commonly involved. There is a predilection for the parieto-occipital regions.
No mass effect
T2 bright
T1 hypo
Enhancement uncommon
Diffusion restriction is present
Where is Broca’s area located?
Where is Wernicke’s area located?
Broca’s area is in the frontal operculum.
Wernicke’s area is in the superior posterior temporal lobe.
What are the major branches of the maxillary artery?
Middle meningeal artery Accessory middle meningeal artery Descending Palatine artery Facial, sinus and nasoorbital branches Sphenopalatine, infraorbital, posterior superior alveolar, artery of the vidian canal
What white matter disease distribution is characteristic of early CADASIL?
Anterior temporal lobe
External capsule
Which foramina contain each branch of CN5?
The ophthalmic, maxillary and mandibular branches leave the skull through three separate foramina: the superior orbital fissure, the foramen rotundum and the foramen ovale, respectively
What is the arterial supply of the medulla oblongata?
PICA supplies the lateral aspect of the medulla
anterior spinal artery supplies the entire medial aspect
direct branches of the vertebral artery supplies an area between the other two main arteries
What are the common causes of stroke in a young patient and in a child?
younger patient
Emboli
Arterial dissections
Vasculopathy (FMD, vasculitis)
Drug abuse
child
Emboli from congenital heart disease
Venous thrombosis
Blood dyscrasias (i.e., sickle cell disease)
What are the manifestations of NF2?
MIS ME:
Intracranial schwannomas (bilat IAC schwannomas are diagnostic of NF2)
Meningiomas
Spinal ependymomas
Can also be associated with syringomyelia and cataracts
Describe the McDonald diagnostic criteria
criteria for MRI diagnosis of multiple sclerosis
Dissemination in space:
requires ≥1 T2 bright lesions in two or more of the following locations 1:
periventricular
juxtacortical
infratentorial
spinal cord (exclude if pt has brainstem/spinal cord syndrome)
Dissemination in time:
A new lesion not present on prior MR
2 lesions, a symptomatic lesion with enhancement and another T2 bright lesion without enhancement.
What is the etiology of Wernicke encephalopathy?
Thiamine deficiency (vit B1), typically seen in alcoholics.
Can also be seen due to: starvation prolonged TPN w/o supplementation post bariatric surgery hyperemesis gravidum gastrointestinal malignancy chronic dialysis
What are the MR imaging findings of Wernicke encephalopathy?
Symmetric (bilateral) T2/FLAIR hyper in the: mamillary bodies dorsomedial thalami tectal plate periaqueductal area around the 3rd ventricle
these regions can show contrast enhancement and diffusion restriction.
What is the classic clinical presentation of Wernicke encephalopathy?
Triad of ophthalmoplegia, ataxia and confusion
Synchronous pineal and suprasellar masses strongly suggest what pathology?
Germinoma
What are the characteristic imaging findings of a germinoma (pineal)?
CT hyperattenuating
MRI:
T2 iso to gray matter
+ve diffusion restriction
pineal calcifications are engulfed by the tumor (as opposed to exploded)
Look for synchronous pineal and suprasellar masses, CSF dissemination and invasion of adjacent parenchyma.
What is the typical MR imaging appearance of Lhermitte-Duclos disease?
A.K.A. dysplastic cerebellar gangliocytoma
Rare mass-like lesion in the cerebellar hemispheres.
Well circumscribed, T1 hypo, T2 hyper with parallel striated of gyriform architecture to the thickened folia (best on T2)
Enhancement and calcification rare
No restriction
What is the distribution of signal abnormality in heroin leukoencephalopathy?
Symmetric T2 hyper +/- restriction in:
posterior cerebral white matter splenium of corpus callosum posterior limb of internal capsule extending inferiorly into the pontine corticospinal tracts (characteristic) cerebellar peduncles cerebellar white matter
predilection for the corticospinal tract and medial lemniscus.
What is the typical location of a hypothalamic hamartoma?
Hypothalamic hamartomas arise from the tuber cinereum (floor of third ventricle).
Lack of enhancement and long-term stability favors this diagnosis.
They’re associated with gelastic seizures (uncontrollable laughter).
What is the differential diagnosis for basal ganglia T1 hyperintensity?
Mostly from deposition of T1hyper elements in the basal ganglia:
1- Calcium (idiopathic, calcium and phosphate abnormalities)
2- hepatic failure (wilson’s disease, hepatocerebral degeneration)
3- Toxins/ischemia (CO, long-term TPN [manganese], hyperglycemia, gadolineum chelates, global hypoxia)
4- Blood (methaemoglobin)
5- Japanese encephalitis
6- Hamartoma in NF1
7- kernicterus in neonates
What is the differential diagnosis for basal ganglia T2 hyperintensity?
LINT
1- Lymphoma
2- Ischemia (hypoxia, venous infarct)
3- Neurodegen/metabolic (wilson, huntington, Creutzfeldt-Jakob, methylmalonic acidaemia, mitochondrial diseases, extrapontine myelinolysis)
4- Toxins (CO, cyanide, hypoglycemia, methanol)
What is the etiology of progressive multifocal leukoencephalopathy and what group of patients are affected?
PML is a demyelinating process caused by the JC polyomavirus.
The virus is active in severely immunocompromised patients (AIDS, lymphoproliferative/myeloproliferative dissorders, immunosuppressive therapy, congenital immunodeficiency).
True of false:
MRI lesions due to progressive multifocal leukoencephalopathy involve primarily the white matter, are usually symmetric and nonenhancing.
FALSE
MRI lesions due to progressive multifocal leukoencephalopathy involve primarily the white matter, are usually ASYMMETRIC and nonenhancing.
Some involvement of grey matter structures is present in 50% of cases.
What finding involving the ventricles differentiates congenital cerebral enlargement (hemimegalencephaly) and acquired cerebral enlargement (edema, gliomatosis)?
In hemimegalencephaly, the ipsilateral ventricle is enlarged as well.
What MRI findings can be present in hemimegalencephaly?
Asymmetrically enlarged cerebral hemisphere and ipsilateral ventricle.
White matter abnormalities: advanced myelination, focal heterogeneous T1 signal.
Neuronal migration abnormalities (polymicrogyria, pachygyria, heterotopia)
Calcifications
May have secondary brain atrophy in later stages due to prolonged seizures.
Which pathology is the hot cross bun sign associated with?
Give other MRI findings
Multiple system atrophy
Other findings:
Cerebellar, middle cerebellar peduncle and pontine atrophy
Lateral putaminal linear t2 hyperintensity
Putaminal atrophy
What are the abnormalities and imaging findings of Sturge-Weber Syndrome?
It is a sporadic congenital syndrome consisting of:
- facial nevus flammeus (port wine stain)
- choroidal angiomas
- pial angiomatosis (ipsilateral to facial abnormalities)
Imaging findings:
- Gyriform calcifications
- pial angiomatosis
- Ipsilateral choroid plexus enlargement
- Eventually, progressive atrophy and gliosis due to chronic venous ischemia.
What is the differential diagnosis of bilateral symmetric striopallidodentate calcinosis in an adult?
Fahr disease
Hypoparathyroidism
Pseudohypoparathyroidism
Hyperparathyroidism
What is the most common type of low grade astrocytoma?
Mean age of presentation and most common presentation?
Imaging findings?
Fibrillary astrocytoma
Mean age of 35, 75% present with seizures
Imaging:
Majority located in supratentorial brain.
T1hypo T2hyper no significant enhancement
cysts and calcification are rare
What is the classic imaging appearance characteristic of cerebellar hemangioblastomas?
Cystic mass with an enhancing mural nodule
What is the boundary between the intra-axial and extra-axial space?
The pial surface
What is the cell of origin of meningioma
Arachnoid cap cell
What are the findings in a Chiari III malformation?
Chiari II
low occipital and/or high cervical meningo-encephalocele
TRUE OR FALSE
The presence of irregular vessels, with flow voids, allows you to differentiate a hemangiopericytoma (solitary fibrous tumor) from a meningioma
FALSE
Although helpful in differentiating the two, it is not sufficient to exclude a meningioma.
Give 3 findings that differentiate hemangiopericytoma from meningioma
No calcification
No hyperostosis
Tends to be lobulated
What are the imaging findings of idiopathic intracranial hypertension?
AKA pseudotumor cerebri
Posterior globe flattening (most specific) Optic nerve sheath distention Optic nerve tortuosity Pituitary deformity Empty sella Slit like ventricles Acquired tonsillar ectopia
(several other findings)
What are the complications of an intracranial abscess?
Choroid plexitis
Intraventricular rupture
- Abscess capsule is thinnest near the ventricle
- Often fatal
Leptomeningitis/Ependymitis
Development of daughter abscessesWhat MRI features allow differentiation between GBM and intracranial abscess?
A cystic lesion that markedly restricts centrally is an abscess until proven otherwise, although GBM can sometimes centrally restrict.
Other findings:
GBM has thick nodular capsule
Abscess has thin regular capsule
Intermediate to low T2 signal capsule favors abscess
Restricted diffuse of enhancing wall favors GBM
Multiple similar rounded lesions at the grey-white matter junction favors abscess
irregular mass with adjacent secondary lesions embedded in the same region of ‘oedema’ favours GBM
Extensive edema to lesion size favors abscess
TRUE OR FALSE
Lentiform nuclei involvement is typical of early HSV encephalitis
FALSE
The lentiform nuclei are usually spared
What is the causative agent in progressive multifocal leukoencephalopathy?
In immunocompromised patients, it is caused by reactivation of the JC (John Cunningham) virus.
TRUE OR FALSE
In cases of progressive multifocal leukoencephalopathy, there is mass effect on the adjacent sulci because of the edema.
FALSE
PML is a demyelinating process and there is no mass effect on the adjacent sulci. When evaluating white matter abnormality in immunocompromised patients, it is important to assess the adjacent sulci for the presence of mass effect.
What are the MRI features of neurotoxoplasmosis?
Presents in immunocompromised patients
Multifocal ring-enhancing masses at the gray matter-white matter junction
involvement of the basal ganglia and thalami
periventricular involvement
generous surrounding vasogenic edema
T1: iso-hypo
T2: iso-hyper
G+: ring enhancement
What are the imaging findings of progressive multifocal leukoencephalopathy?
Presents in immunocompromised patients
Confluent, bilateral, asymmetric supratentorial white matter and thalamic involvement.
Also involves U-fibers.
T1 hypo T2 hyper No mass effect No enhancement Restricts on DWI
How do you differentiate retinal from choroidal detachment on imaging?
In retinal detachment, the detachment is limited anteriorly by the ora serrata, compared to the choroidal detachment that is not limited and extends beyond it.
The ora serrata marks the junction between the retina and the ciliary body. It is located anteriorly bilaterally, approximately 10 and 2 o’clock
In retinal detachment, the detachment converges posteriorly on the optic disc, compared to the choroidal detachment that diverges at the disc.
What is the most common etiology of leukocoria in children?
Retinoblastoma, almost all present <6 years of age
What is Tolosa-Hunt syndrome?
Tolosa-Hunt syndrome (THS) is an idiopathic inflammatory condition that involves the cavernous sinus and orbital apex, and is essentially a clinical diagnosis of exclusion.
In lacrimal gland pathology, what morphologic criteria can you use to differentiate inflammatory from neoplastic lesions?
In inflammatory lesions, the almond/oval shape of the lacrimal gland is preserved, whereas in neoplasm it becomes rounded.
What findings in the corpus callosum allow you to differentiate holoprosencephaly from partial agenesis of the corpus callosum?
The corpus callosum forms in a anterior to posterior sequence, therefore the splenium and rostrum are absent in partial agenesis of the corpus callosum.
In holoprosencephaly, the splenium and body are present and the genu of the corpus callosum is absent, since telencephalic cleavage occurs in a posterior to anterior direction.
TRUE OR FALSE
Retinal hemorrhage in an infant is specific for non accidental injury
FALSE
It can be seen in a variety of traumatic and non traumatic settings
PED
Why are skull fractures difficult to date?
No periosteal reaction
Simple skull fracture may take up to 6 months to heal in an infant, and 12 months in older child.
When is the peak occurence of neuronal migration?
3-5 months of gestation. Neurons migrate aided by radial glial cells from the periventricular region to the cortical plate
In-utero exposure to what agents can lead to malformations of cortical development? (4)
Infections (CMV or toxoplasmosis)
Ethanol
Cocaine
Ionizing radiation
PED
What are the 3 large classification groups in cerebral cortical malformation?
- Disorders resulting from abnormalities of cell proliferation or apoptosis
- Disorders resulting from abnormal neuronal migration
- Disorders resulting from abnormal cortical organization
PED
What cerebral cortical malformations result from abnormalities of cell proliferation or apoptosis?
microcephalies
megalencephalies
Neoplastic/non-neoplastic abnormal proliferation (TS, DNET, ganglioglioma, etc.)
PED
What cerebral cortical malformations result from abnormal neuronal migration?
lissencephaly/band heterotopia
cobblestone complex (lissencephaly type 2)
grey matter heterotopia
PED
What cerebral cortical malformations result from abnormal neuronal organization?
Polymicrogyria
Schizencephaly
Cortical dysplasia (without balloon cells)
microdysgenesis
PED
What environmental insults are linked to microcephaly?
Irradiation Maternal alcoholism Maternal phenylketonuria Anticonvulsant drugs Rubella Excess vitamin A or organic mercurials
What are the MRI findings of hemimegalencephaly?
Enlargement of a hemisphere
Disorganized appearing sulcal/gyral architecture
Thickened cortex
Poor gray-white matter differentiation {often}
Abnormal T2 prolongation in the underlying white matter
Volume of white matter is typically increased
Heterotopias, cortical dysplasias or polymicrogyria
Ipsilateral lateral ventricle is enlarged
Ipsilateral frontal horn has a characteristic appearance with anteriosuperior straightening
Brainstem and ipsilateral cerebellum can also be involved
What is the most common form of grey matter heterotopia?
subependymal heterotopia
Patients with isolated subependymal heterotopia often have _________ intelligence and development with the most common clinical manifestation being ________.
normal
epilepsy
What is the pathological process in subependymal heterotopia?
there is a complete failure of some cells to migrate resulting in an abnormal accumulation of cells in the periventricular region which appear nodular on imaging. Pathologically these nodules contain astrocytes and neurons of varying sizes. The heterotopia can be unilateral focal, bilateral focal or bilateral diffuse.
TRUE OR FALSE
CMV infection is a well-recognized cause of polymicrogyria
true
Name suspected causes of polymicrogyria (categories)
Hypoxia-ischemia
Infection (CMV)
In utero toxic exposures
Genetic mutations
What is layered polymicrogyria?
Pathologically two major subtypes have been described: layered polymicrogyria in which there is a cell sparse zone of laminar necrosis in cortical layer V and unlayered polymicrogyria in which there is no cell sparse layer. The layer of laminar necrosis is thought to be responsible for the increased infolding of the cortex in these patients secondary to increased growth differences between adjacent layers.
What are the three major features of polymicrogyria?
Abnormal gyral pattern
Increased cortical thickness
Serrated appearance of the gray white junction
What abnormalities are part of septo-optic dysplasia?
absence of septum pellucidum
optic pathway hypoplasia
2/3 of cases: hypothalamic-pituitary dysfunction
1/2 of cases: schizencephaly
What are the spine plain film findings in spinal dysraphism?
Although not an adequate screening tool, the following can be seen:
Non-fused posterior vertebral elements
Pedicular widening
Bony spurs
Vertebral malformations (such as butterfly, block or hemivertebrae)
At what age does the conus medullaris reach the normal adult level of L1-L2?
By 3 months of age.
What are the MRI/CT findings in pseudotumor cerebri?
OCULAR
- Prominent subarachnoid space around optic nerves
- Vertical tortuosity of the optic nerves
- Flattening of the posterior sclera
- Intraocular protrusion of the optic nerve head
- Enhancement of intra-ocular optic nerves
ENLARGED ARACHNOID OUTPOUCHINGS
- Partial empty sella turcica
- Enlarged Meckel cave
- Prominent arachnoid pits
- Small meningoceles (temporal bone, sphenoid wing)
Bilateral venous sinus stenosis
- Lateral segments of transverse sinuses
Slitlike ventricles
Acquired tonsillar ectopia
Describe direct vs indirect caroticocavernous fistula
Direct: direct communication between intracavernous ICA and cavernous sinus
Indirect: communication exists via branches of the carotid circulation (ICA or ECA)
What is hypertrophic olivary degeneration?
Hypertrophic olivary degeneration is a rare condition characterised by unique pattern of trans-synaptic degeneration. It is caused by a lesion in the triangle of Guillain and Mollaret, resulting in hypertrophy of the inferior olivary nucleus. The three corners of the triangle are:
red nucleus
inferior olivary nucleus
contralateral dentate nucleus
Interruption of either connections between the dentate nucleus and contralateral red nucleus (dentatorubral tract, superior cerebellar peduncle) or the connection between the red nucleus and ipsilateral inferior olivary nucleus (central tegmental tract) leads to changes in the olive.
What is the classic clinical presentation of hypertrophic olivary degeneration?
Palatal myoclonus
What are the MRI findings of hypertrophic olivary degeneration?
Inferior olivary nucleus hypertrophy and T2 hyperintensity.
Typically, within a few months T2 signal increases and lasts 3-4 years, whereas hypertrophy occurs later (at about one year), and resolves by 3-4 years.
Lesion/mass can be present in the triangle of Guillain and Mollaret
What is the triangle of Guillain and Mollaret?
The triangle of Guillain and Mollaret, also known as dentatorubro-olivary pathway, has three corners:
- red nucleus
- inferior olivary nucleus
- contralateral dentate nucleus
Connecting fibres are only identified between the red nucleus and inferior olivary nucleus (central tegmental tract) and between the red nucleus and the contralateral dentate nucleus via the superior cerebellar peduncle (rubrodentate fibers).
No connecting tract is present between the inferior olivary nucleus and contralateral dentate nucleus.
Depending on the location of interruption, cerebellar atrophy or hypertrophic olivary degeneration can ensue.
What is the most common type of pituitary adenoma?
Prolactinoma
What are the imaging findings of pituitary apoplexy?
Hemorrhagic or non-hemorrhagic pituitary necrosis
Pituitary region mass
Peripheral enhancement
Fluid debris/fluid-fluid level
Surrounding edema may be seen in optic tracts and chiasm.
What are the causes of epidural lipomatosis?
Glucocorticoid excess - Steroid administration - Endogenous (Cushing) Obesity Idiopathic
Where does a cephalhematoma occur (between which components of the skull)?
It is hemorrhage between the outer table of the skull and its periosteum.
TRUE OR FALSE
Cephalhematomas do not cross suture lines
TRUE
Cephalhematomas are limited by the periosteum, which is tethered to the suture lines.
Where are senescent calcifications of the globe located?
In the sclera. They are calcifications of the tendinous insertion of the sclera of the globe.
What are the CT and MRI findings of skull hemangioma?
Osteolytic lesion centered in the diploic space with slight bone expansion. Outer table involvement is greater than inner table.
Linear spicules (bone trabeculae) are often present and oriented perpendicularly to the inner and outer tables. Appear as ossification on CT and signal void on MRI.
Avid enhancement on MRI.
Can contain T1 hyperintense component (fat). T2 hyperintensity represents slow flowing blood.
What is the differential diagnosis of bony spicules in a calvarial mass?
Hemangioma
Metastasis
Osteosarcoma
Head & Neck imaging - case review series
What is the hummingbird sign and what diagnosis does it represent?
Flattening or concave outline to the superior aspect of the midbrain on sagittal view, which should be upwardly convex.
Refers to progressive supranuclear palsy
TRUE OR FALSE
If a posterior fossa mass extends into the foramen of Luschka, it is highly unlikely to be intra-axial in origin.
TRUE
Rosenbloom
What is the imaging appearance of a pleomorphic xanthroastrocytoma?
Rare tumor, typically found in young patients
Almost always supratentorial in location, most often temporal lobe
Commonly cystic mass, with enhancing mural nodule.
Little surrounding edema
On MRI, solid component is hypo/iso T1 and iso/hyper T2.
Calcification is rare, may have dural tail/leptomeningeal component.
Name this syndrome:
Idiopathic inflammatory condition that involves the cavernous sinus and orbital apex, and is essentially a clinical diagnosis of exclusion. There is infiltration of lymphocytes and plasma cells, along with thickening of dura mater within the cavernous sinus.
Tolosa-Hunt syndrome
What is the DDx of pachymeningeal enhancement?
Intracranial hypotension Idiopathic pachymeningitis Postoperative empyema metastases (breast, prostate) Meningioma Secondary CNS lymphoma Granulomatous disease
What is the most common cause of intracranial hypotension?
CSF leak
What are the MRI findings in intracranial hypotension?
Most common findings:
Diffuse pachymeningeal thickening and enhancement
Dural venous engorgement (rounded sinus in cross-section)
Tonsillar herniation
Subdural collections
Other findings:
Pituitary gland enlargement
subdural hematomas
cerebral edema
Sagging brainstem
Downward drooping of splenium of corpus callosum
Decreased fluid within optic nerve sheath
Optic chiasm drapping over the pituitary gland
Decreased mamillopontine distance
NEURO
What is the hockey stick sign and what pathology does it most commonly refer to?
AKA pulvinar sign
The hockey stick sign refers to the hyperintense signal involving the pulvinar and dorsomedial thalamic nuclei bilaterally on FLAIR
Most commonly represents variant creutzfeldt-Jakob disease.
NEURO
What pathologies give the hockey stick sign?
AKA pulvinar sign
Variant Creutzfeldt-Jakob disease
Fabry disease
Bilateral thalamic infarcts
ADEM
What is the pulvinar?
The pulvinar nuclei are nuclei located in the postero-lateral aspect of the thalami bilaterally.
What are the 4 most common intracranial manifestations of tuberous sclerosis?
Cortical tubers
Subependymal nodules
Subependymal giant cell astrocytoma
White matter abnormalities
TRUE OR FALSE
Most cortical tubers do not enhance on post-contrast MRI.
TRUE
Only 10% enhance.
T2 hyper, T1 hypo, most calcify after 2 years of age.
What is a cortical tuber?
Cortical tubers are developmental abnormalities of the cerebral cortex in patients with tuberous sclerosis, characterized by a loss of the normal six-layer structure of the cortex and the presence of dysmorphic neurons and large astrocytes.
In tuberous sclerosis, the subependymal nodules represent what type of mass?
hamartoma
What are the MRI findings of subependymal nodules in tuberous sclerosis?
They are hamartomatous lesions.
Variable signal, but frequently:
T1 hyper
T2 iso-hyper
88% calcify
Variable enhancement
What allows reliable imaging differenciation of a subependymal nodule from a subependymal giant cell astrocytoma?
The only reliable differentiating factor on imaging is serial growth.
What are the MRI findings in Creutzfeldt-Jakob disease?
Can be unilateral or bilateral, symmetric or asymmetric
T2 hyperintensity involving:
- Basal ganglia (putamen, caudate)
- Thalamus (pulvinar sign)
- Cortex
- White matter
Diffusion restriction within these regions.
Rapidly progressing cerebral atrophy
What is the most common early manifestation of Creutzfeldt-Jakob disease on MRI?
Most sensitive?
Most common early: Cortical T2 hyperintensity
Most sensitive: Diffusion restriction
What are the 2 most common tumors located in the lateral and fourth ventricles?
Ependymoma (in children)
Subependymoma
What are the 2 most common tumors located in the atrium of the ventricle?
Meningioma
Metastasis
TRUE OR FALSE
Ependymomas in adults are more commonly supratentorial intra-axial
TRUE
What is the most common site of origin of medulloblastoma?
Cerebellum, most commonly vermis. Usually seen arising from the roof of the 4th ventricle.
TRUE OR FALSE
Both ependymoma and subependymoma typically enhance on post contrast imaging.
FALSE
Ependymoma enhances, but not subependymoma. If there is no enhancement, ependymoma is unlikely.
Is the infundibular stalk normally wider at the median eminence or inferiorly along its insertion with the pituitary gland?
At its median eminence, it tapers as it approach the pituitary gland.
What neurocutaneous syndrome is dysplastic gangliocytoma (l’hermitte-duclos disease) associated with?
Cowden syndrome
What disease processes affect the basilar leptomeninges?
- Infection: TB, neursyphilis, pyogenic infections, cryptococcus
- Sarcoidosis
- Leptomeningeal
metastases - Lymphoma
- Chemical meningitis (drugs, fat from ruptured dermoid)
TRUE OR FALSE
Unlike pyogenic brain abscesses, the lesions in neurotoxoplasmosis do not demonstrate diffusion restriction.
TRUE. The neurotoxoplasmosis abscesses do not demonstrate central diffusion restriction
What is the most common location for gangliogliomas?
temporal lobe, followed by frontal lobe
What is the most common toxic exposure resulting in injuries or infarction to the globus pallidus?
Carbon monoxide poisoning
Others: cyanide and manganese (hyperalimentation)
What is Wallenberg syndrome?
Lateral medullary syndrome (or Wallenberg syndrome) is an acute ischemic infarct due to occlusion of the vessels supplying the lateral medulla oblongata; most commonly occlusion of intracranial portion of the vertebral artery followed by PICA and it’s branches.
What is Wallerian degeneration? Name 6 causes.
It is a secondary manifestation of brain injury distal to the causative lesion. It represents progressive axonal degradation, resulting in gliosis and volume loss.
Typically involves the corticospinal pathways.
Infarction Trauma Demyelinating disease Neurodegenerative processes Neoplasia/radiation injury
What is the radiologic hallmark of Dandy-Walker malformation?
Communication of a retrocerebellar cyst with the fourth ventricle (absent or hypoplastic vermis).
What is the most common location of supratentorial ependymomas?
The trigone of the lateral ventricle
What is the differential diagnosis of intraparenchymal cyst?
Perivascular space Neuroglial cyst Hippocampal sulcus remnant cyst Porencephalic cyst Intraparenchymal epidermoid/arachnoid cysts can occur, but rare
What is the differential diagnosis of intraventricular cysts?
Ependymal cyst Choroid plexus xanthogranuloma Colloid cyst Epidermoid cyst Trapped 4th ventricle
What neurocutaneous syndrome is associated with multiple hemangioblastomas?
Von-Hippel-Lindau
What is the differential diagnosis of tram-track enhancement pattern of the optic nerve sheath?
Meningioma Sarcoid Lymphoma Metastatic disease Pseudotumor
What are the 2 most common neoplasms in the peripineal region in adults?
Meningioma
Primary glioma
What is the TORCH infection typically associated with periventricular calcification?
CMV
TRUE OR FALSE
Plexiform neurofibroma is at significant risk of malignant transformation
TRUE, unlike localised neurofibromas and diffuse cutaneous neurofibromas
What characteristics of a suspected nerve sheath tumor suggest a malignant nature?
- Large tumor size (>5cm)
- Ill-defined infiltrative margins
- Rapid growth
- Heterogeneous signal intensity
- Erosion of adjacent bone
These findings should raise suspicion for MPNST
What are the 3 most common primary cavernous sinus tumors?
Schwannoma
Meningioma
Cavernous hemangioma
Name some signs of cavernous sinus invasion by a pituitary adenoma
Encasement of the intracavernous ICA by >30% of its diameter
Tumour extension lateral to the top (12 o’clock) of the ICA
Interposition of abnormal soft tissue between the lateral wall of the CS and the ICA
What does CLIPPERS stand for?
Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids
What are the MRI findings in CLIPPERS?
multiple punctate patchy and linear regions of contrast enhancement relatively confined to the pons.
Similar changes may be present in other regions including cerebellar peduncles and cerebellar hemispheres
T2 hyperintense
What is the MRI appearance of a clival chordoma?
Typically midline, can originate more laterally from the spheno-occipital synchondrosis. Can extend into the cavernous sinus.
T1: intermediate signal with focal high-signal areas representing hemorrhage or high protein.
T2: hyperintense with hypointense areas representing residual fragments or sequestrations of bone.
What is the DDx of a clival mass?
Metastasis Chordoma (midline) Chondrosarcoma (off-midline: petroclival synchondrosis) Plasmacytoma Intraosseous lymphoma Neuroenteric cyst
What is the most common primary malignant extracranial neoplasm to invade the cavernous sinus? How does it spread?
Nasopharyngeal carcinoma
Skull base erosion
Perineural spread along branches of CNV
What is the site of origin of nasopharyngeal juvenile angiofibroma?
sphenopalatine foramen
What are the imaging features of an intracranial dermoid cyst?
Typically midline, most commonly posterior fossa/vermis and suprasellar/subfrontal.
CT: Well defined fat density lobulated masses. Can have wall Ca2+. If enhancing: thin peripheral rim.
MRI: T1hyper, T2 variable, no enhancement
If ruptured, T1hyper foci in subarachnoid space with extensive pial enhancement if chemical meningitis.
What is the clinical triad of Tolosa-Hunt syndrome?
Unilateral ophthalmoplegia, cranial nerve palsies, dramatic response to corticosteroids
What is Tolosa-Hunt syndrome?
Idiopathic inflammatory condition
Retro-orbital pseudotumor extending to the cavernous sinus.
There is a non-specific low grade inflammatory process with lymphocytes and plasma cells.
What are the MRI findings in Tolosa-Hunt syndrome?
Enlarged cavernous sinus containing abnormal soft tissue T1iso to muscle T2 variable (hypo to hyper) Contrast enhancement on C+ Focal ICA narrowing
What are the MRI findings in inflammatory myofibroblastic tumor?
Inflammatory cell infiltration and variable fibrotic response. Typically affects the orbit, extends into cavernous sinus in 10% of patients.
Focal enlargement of an extra-ocular muscle and a soft-tissue lesion replacing the orbital fat, which may extend into the cavernous sinus.
Hypo-iso T2
C+: Enhances
Can be indistinguishable from orbital pseudotumor on imaging
What is idiopathic hypertrophic pachymeningitis?
Rare inflammatory disease with diffuse dural involvement.
On MR, there is dural enhancement and thickening, which may be extensive or localized.
Can involve the cavernous sinus, leading to thrombosis.
There can be white matter edema and hydrocephalus due to venous hypertension.
What are the MR findings of a carotid cavernous fistula?
Dilated cavernous sinus
Multiple signal intensity void structures
Gradient echo: the flow voids show high signal intensity
Enhancing vessels on MR angiography
Proptosis
Enlarged superior ophthalmic vein
Orbital fat stranding
Enlarged extraocular muscles
TRUE OR FALSE
Fat deposits within the cavernous sinus can be normal
TRUE
This can also be seen in obese individuals, those taking corticosteroids or those with Cushing syndrome.
When a mass arises in the lateral wall of the cavernous sinus, what are the top 2 differential diagnoses?
Meningioma
Cavernous hemangioma
What is the DDx for inflammatory, infectious and granulomatous lesions involving the cavernous sinus?
Tuberculosis
Sarcoirdosis
Tolosa-Hunt Syndrome
Fungal Infection
Wegener Granulomatosis
Inflammatory myofibroblastic tumor
Idiopathic hypertrophic pachymeningitis
What is the DDx for benign neoplastic lesions involving the cavernous sinus?
Schwannoma
Meningioma
Cavernous hemangioma
Pituitary adenoma
Chordoma Plexiform neurofibroma Melanocytoma Juvenile angiofibroma Dermoid/epidermoid cyst
What is the DDx for malignant neoplastic lesions involving the cavernous sinus?
Metastases
Nasopharyngeal carcinoma
Sphenoid sinus carcinoma Lymphoma/leukemia Rhabdomyosarcoma Chondrosarcoma Malignant peripheral nerve sheath tumor PTLD LCH/Rosai-Dorfman/Erdheim-Chester
