Neuro Flashcards
Cause of CN3 (occulor motor) palsy
Think posterior communicating artery aneurysm
Cranial nerve 6 (abducens) palsy
Think raised ICP (downward displacement of the brainstem = stretching of the 6th CN.
Brain myelination progression order
Inferior to superior
Posterior to anterior
Central to peripheral
What is the last part of the brain to myelinate?
Subcortical white matter
What parts of the brain are myelinated at birth?
Brainstem
Posterior limb internal capsule
How does the corpus callosum form?
Front to back
i.e. Rostrum to Splenium
Wide spaced vertical ventricles, dilation of the occipital horns, intracranial lipoma. Diagnosis?
Agenesis of the corpus callosum
Vermis (cerebellar) hypoplasia, cystic dilatation of the 4th ventricle, lambdoid inversion of the torcular. Diagnosis?
Dandy Walker malformation
Spectrum of disease.
Mega cisterna magna (normal cerebellum and posterior fossa)
to Classic DWM (tiny cerebellum, expanded posterior fossa).
MCM - Blake Pouch - Variant DWM - Classic DWM
Large lateral ventricle on one side, with ipsilateral hamartomatous overgrowth of that cerebral hemisphere. Diagnosis?
Hemimegalencephaly
(Ramussen’s encephalitis = BIG ventricle, SMALL cerebral hemispehere)
Types of holoprocencephaly?
Lobar - <50% focal fusion of the anterior brain.
SemiLobar - >50% fusion of the anterior brain.
ALobar - Zero midline cleavage. Single ventricle.
What are the different types of Lissenchephaly?
Lissencephaly (Type 1) - failure of grey matter migration. Agyria (no gyri), thick cortex, “figure of 8” shaped brain.
Lissencephaly (Type 2) - overmigration of grey matter. Cobblestoned thickened cortex. Associated with congenital muscular dystrophy.
What is Double cortex band heterotopia?
Disorganised under migration of grey matter. Double cortex appearance, normal/mildly simplified gyri. Second layer of grey matter seen around the ventricles.
What is periventricular nodular heterotopia?
Under migration of grey matter. Nodular grey matter deposited around the periventricular region.
Cleft in the brain extending from ventricle to the surface filled with CSF. The cleft is lined with grey matter. Diagnosis?
Schizenchephaly (OPEN LIP) - Congenital split brain, lined with grey matter.
If cleft is not filled with CSF, but still lined with grey matter, then its closed lip schizencephaly.
Cleft in the brain extending from ventricle to the surface filled with CSF. The cleft is NOT lined with grey matter. Diagnosis?
Porencephaly - aquired split brain, usually secondary to vascular insult resulting in encephalomalacia. NOT lined with grey matter.
If cleft is lined with grey matter then it’s shizencephaly.
Define Chiari 1 malformation
Cerebellar tonsils >5mm below the level of basion-opistion
Features of chiari 2 malformation
Myelomeningocele
Low lying cerebellar tonsils and torcular
Thinned corpus callosum
Tectal beaking
If also has occipital encephalocele = Chiari Type 3
Patient with urinary incontinene, confusion, and ataxia. CT head shows ventricles out of proportion to atrophy, and upward bowing of the corpus callosum. Diagnosis?
Normal pressure hydrocephalus.
“Wet, Wacky, Wobbly”
Urinary incontinence, confusion, ataxia.
Type of oedema that comes secondary to infarction?
Cytotoxic oedema - INTRAcellular fluid secondary to malfunction of the Na/K+ pump. Tends to favour grey matter, causing loss of grey-white matter differentiation.
Type of oedema that comes secondary to tumour/infection?
Vasogenic oedema - EXTRAcellular fluid. Oedema tracking through the white matter. Spares the grey matter.
Alcoholic, low Na which is rapidly corrected. Now encephalopathic, low GCS, quadraparesis.
MRI shows T2 bright in central pons. Restricted diffusion in central pons.
Diagnosis?
Osmotic demyelination syndrome
Alcoholic. Confusion, ataxia, seizures, and spasticity.
CT head shows hypoattenuating regions of the corpus callosum.
MR shows T2 hyperintensities in the corpus callosum.
Diagnosis?
Marchiafava-bignami disease - demyelination of the corpus callosum.
Acute symptoms of headache, dizzyness, memory loss.
CT shows low density in the globus pallidus.
MR shows T2/FLAIR high signal in globus pallidus.
Diagnosis?
Carbon monoxide poisoning
Carbon monoxide causes “Globus warming”
Headache, dizziness, optic neuritis, vomiting.
CT shows low density in putamen bilaterally.
MRI shows high T2/FLAIR signal in the putamen.
Diagnosis?
Methanol poisoning
Previous chemoetherapy. Bilateral asymettric subcortical white matter oedema within the occipital lobe. Does not restrict on DWI.
Diagnosis?
PRES (Posterior Reversible Encephalopy Syndrome)
Post chemotherapy. New confusion.
MRI shows bilateral diffuse, confluent high T2/FLAIR signal in the subcortical white matter centrum semiovale.
Diagnosis?
Methotrexate induced leukoencephalopathy
IVDU. New cerebellar ataxia, and pseudo bulbar symptoms.
MRI shows symmetrical “butterfly” high T2 signal in centrum semiovale, posterior limb internal capsule, and deep cerebellar white matter.
Diagnosis?
Heroin induced leukoencephalopathy (Chasing the dragon)
Common locations for MS white matter lesions?
Juxtacortical
Corpus callosum
Periventricular
Infratentorial
Basal ganglia rare.
McDonald Diagnostic criteria for MS?
> 1 lesion disseminated in space (juxtacortical, Corpus callosal, periventricular, infratentorial).
> 1 lesion disseminated in time - >1 month
Active lesions enhance on MR
Old lesions do not enhance (both are T2 bright)
Female patient, 37 y/o, presents with seizure.
MR brain shows large ring enhancing lesion with incomplete ring sign. Minimal mass effect for the size of the lesion.
Diagnosis?
Tumefactive Demyelination.
15 y/o presents with seizure after having a vaccine.
MR shows multiple “incomplete ring” enhancing lesions, sparing the calloso-septal interface.
Diagnosis?
ADEM - Acute Disseminated Encephalomyelitis.
60y/o presents with dementia like symptoms.
MRI shows multiple, small, confluent high T2 signal in centrum semiovale sparing the subcotical U fibres.
Diagnosis?
Subcortical Arteriosclerotic Encephalopathy (small vessel dementia)
CADASIL - cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy - presents at a younger age due to hereditary nature.
5 year old present with progressive impariment of motor/cognitive function.
MRI shows high FLAIR signal in parieto-occipital white matter sparing subcortial U fibres, and extends across the corpus callosum.
Diagnosis?
Adrenoleukodytrophy.
(ALD)
18 month old, convulsions, loss of vision, muscle rigidity.
MRI shows high FLAIR signal in the periventricular white matter in a “tiger stripe” pattern.
Diagnosis?
Metachromatic Leukodystrophy.
Infant with large head, has progressive quadrapaerisis and seizure.
MRI shows high FLAIR signal in the frontal white matter bilaterally.
Diagnosis?
Alexander disease
Ashkenazi Jewish infant with big head. Bloods show elevated NAA.
MR shows diffuse high FLAIR signal throughout the white matter involving the subcortical U fibres.
Diagnosis?
Canavan disease
Infant with a small head.
MRI shows high FLAIR signal in the centrum semiovale and periventricular white matter, with parieto occipital predominance.
Diagnosis?
Krabbe leukodystrophy
MEN 1
Pituitary
Parathyroid
Pancreatic
MEN 2a
PMP
Pheochromocytoma
Medullary thyroid tumour
Parathyroid hyperplasia
MEN 2b
Pheochromocytoma
Medullary thyroid cancer
Mucosal neuroma
Marfanoid features
Patient with cerebellar ataxia, autonomic dysfunction, and parkinsonism.
MRI T2 shows cruciate high signal within the pons, high signal in middle cerebellar peduncles, and cerebellum.
Diagnosis?
Multi system atrophy
(Hot cross bun sign + autonomic dysfunction)
What runs through the cavernous sinus?
CN 3, 4, 5 (V1+2), 6, and the carotid artery
What travels through superior orbital fissure + inferior orbital fissure?
Superior orbital fissure - CN 3, 4, V1, 6
Inferior orbital fissure - V2
What are the Parkinson plus syndromes?
Dementia with Lewy bodies
Multisystem atrophy
Progressive supra nuclear palsy
Cortico-basal degeneration
Patient with abnormal eye movements, instability and falls.
MRI head shows midbrain atrophy with sparing of the pedicles, and flattening of the superior aspect of the midbrain.
Diagnosis?
Mickey mouse sign
Hummingbird sign
Progressive supranuclear palsy.
Patient with alien limb syndrome, asymmetric movement disorders has an MR brain showing asymmetric cortical atrophy, basal ganglia atrophy, and atrophy of the corpus callosum.
Corticobasal degeneration
Patient presents with glioblastomas and intestinal polyps. What is the diagnosis?
Turcot syndrome
16 year old boy with progressive dementia symptoms. MRI shows eye of tiger sign with high signal around the globus pallidus. Diagnosis?
PKAN - Hallervoden Spatz
What is dolichoectasia and it’s associated diseases?
Dilated and ectatic intracranial vessels.
Most commonly vertebro-basilar or internal carotid.
Can cause compression of cranial nerves.
Associated with Marfans, Ehlers-Dahnlos
What is the most common CNS metastases in a child?
Neuroblastoma.
What are the cortically based tumours?
P-DOG
Pleomorphic xanthoastrocytoma
DNET
Oligodendroglioma
Ganglioglioma
What are the imaging appearances of pleomorphic xanthoastrocytoma?
Supratentorial
Cyst with enhancing nodule.
How can you tell the difference between pleomorphic xanthoastrocytoma, pilocytic astrocytoma, and haemangioblastoma?
All 3 appear as cyst with enhancing nodule.
Pleo - Supratentorial, in temporal lobe
Pilocytic - Posterior fossa in kids
Haemangioblastoma - Posterior fossa in adults, VHL
Typical radiological appearance of a DNET?
Paediatric temporal lobe lesions
T2 Bright and Bubbly appearance
Minimal enhancement
Typical radiological appearance of an oligodendroglioma?
Typically occurs in adults
Calcification - ribbon like
Frontal lobe predominant
Expands the cortex
Typical radiological appearance of a ganglioglioma?
Typically found in temporal lobe in teenagers.
Typically presents with seizures.
Mixed solid cystic appearance.
Can have bony remodeling
What are the intraventricular lesions?
Intraventricular lesions are messy
MESS-C
- Medulloblastoma
- Ependymoma
- Subependymoma
- SEGA
- Central neurocytoma
How do you differentiate between an ependymoma Vs medulloblastoma?
Both classically 4th ventricle tumours.
Ependymoma arises from the floor of 4th ventricle, squeezing out of it (toothpaste sign).
Calc + haemorrhage - enhance heterogeneously.
Medulloblastoma arises from the roof of 4th ventricle, protruding into it. Enhance more homogenously.
Which tumour is most likely to metastases to the spine? Ependymoma or medulloblastoma?
Medulloblastoma - metastases
Need to image rest of spine
What condition are Subependymal Giant Cell Astrocytomas associated with?
Tuberous sclerosis.
Where are SEGAs typically located?
At the base of the lateral ventricles near the foramen of Munro.
Hydrocephalus is commonly present.
What age group do SEGAs appear in Vs Subependymoma?
SEGAs appear in children Vs Subependymoma appears in adults.
What is the classical imaging appearance for a Central neurocytoma?
Cystic “Swiss cheese” appearance.
Interventricular lesion.
Tend to calcify a lot (like oligodendroglioma)
Internal haemorrhage is common.
Name two brain tumours that classically calcify?
Oligodendroglioma
Central neurocytoma
Classic imaging appearance for a choroid plexus papilloma?
Cauliflower appearance.
Hydrocephalus due to excess CSF secretion
Homogeneous enhancement
Classic imaging appearances of a meningioma?
Extra axial (CSF cleft sign)
Classically have a dural tail
What is the most common CP angle masses?
Vestibular Schwannoma (75%)
Meningioma (10%)
Epidermoid (5%)
Dermoid
What condition are Schwannoma associated with?
NF 2
How can you differentiate between a dermoid Vs an epidermoid CPA angle mass?
Dermoids are classically midline + contain fat
Epidermoids are classically off midline + restrict avidly
What is the classical imaging appearances of an AT/RT?
Typically occur in the posterior fossa.
Aggressive large heterogenous mass with necrosis
Which low grade tumours classically enhance?
GPS
Ganglioglioma
Pilocytic astrocytoma
SEGA
Classic imaging features of primary CNS lymphoma?
Periventricular
Crosses the corpus callosum
Homogeneously enhancing
What causes gelastic seizures?
Hypothalamic hamartoma
What are the pineal lesions?
GPPP
Germinoma (most common)
Pineal cyst
Pineocytoma
Pineoblastoma
Typical imaging appearances of a germinoma?
Pineal lesion
Heterogeneous mass containing fat and calcification.
Classic imaging features of a pineoblastoma?
PineoBLASToma - “Exploded” calcification
Highly invasive compared to pineocytoma
Classic imaging features of adult Toxoplasmosis CNS infection?
Ring enhancing lesion with LOTS of oedema
Classical imaging features of an Adamantinous Craniopharyngioma?
Supra sella lesion.
- Cystic.
- Peripheral calcification.
- Mostly seen in children.
(Papillary craniopharyngioma is solid, with no calc, in adults)
What are the differences between Adamantinous Craniopharyngioma and Papillary craniopharyngioma?
Both are suprasellar lesion
Adamantinous are cystic with peripheral calcification, seen in kids.
Papillary are mainly solid, with no calc, seen in adults.
What are the leukodystrophies from frontal predominance to occipital predominance?
Alexander disease - frontal
Canavan disease - Diffuse subcortical U
Metachromatic - Periventricular, tigroid
Krabbe - Centrum semiovale and occipital
ALD - Parieto Occipital
What is CADASIL?
CADASIL - cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy - Severe small vessel disease that presents at a young age due to hereditary nature.
How can you differentiate choroid plexus papilloma from choroid plexus carcinoma?
Choroid plexus papilloma enhances homogeneously
Choroid plexus carcinoma enhances heterogeneously
Where do CNS hemangioblastomas occur?
Posterior fossa
Supratentorial (in VHL patients)
Imaging features of optic nerve gliomas
Enlargement of the optic nerve
Enlargement of the optic canal
Kinking of the optic nerve
T2 bright
Typical imaging appearance of vestibular schwannoma
CPA angle mass
Low T1
Heterogeneous High T2
Intense heterogeneous enhancement
How does vein of Galen malformation typically present?
Neonatal high output cardiac failure
Obstructive hydrocephalus
Where does diffuse axonal injury typically occur
Grey white matter junction
Most common brain metastases in adult?
Long Runs? Be My Guest.
- Lung
- Renal
- Breast
- Melanoma
- GI
What is Pick’s disease?
Frontotemporal atrophy
Typically in young men
Type of tauopathy
Classic imaging appearance of Huntington’s disease
Caudate head and putamen atrophy with compensatory dilatation, of the frontal horns of lateral ventricles.
High signal within caudate and putamen
Suprasellar lesions?
SATCHMOE
S - sarcoid
A - aneurysm
T - teratoma, TB
C - craniopharyngioma, chordoma, cleft cyst (rathke)
H - hypothalamic hamartoma/glioma
M - meningioma, metastases
O - optic nerve glioma
E - Eosinphilic granuloma, epidermoid/dermoid
Imaging features of CNS cytomegalovirus.
High T2 oedema typically in a PERIVENTRICULAR distribution.
No enhancement.
Can affect the whole neuro axis.
What is diastematomyelia?
Split cord malformation
Splitting of the distal spinal canal with a bony cleft, resulting in two spinal cords.
What is Moyamoya disease?
Idiopathic, non inflammatory, not atherosclerotic, vascular occlusive disease.
Seen in kids.
Present with hemispheric ischaemic strokes, and watershed infarcts
How can you age subdural haematoma based on MRI blood signal?
TYPE - TIME - T1 SIGNAL - T2 SIGNAL:
Oxy Hb - Immediate - Iso - Iso
Deoxy Hb - 1-2 days - iso - low
Intracellular Met Hb - 2-7 days - high - low
Extracellular Met Hb - 7-28 days - high - high
Hemosiderin - chronic - low - low
TLDR:
T1 signal only becomes high after a couple days
T2 signal only becomes high after a week
Typical MRI appearance of a Rathke Cleft Cyst?
Congenital intrasellar lesion found in kids.
60% have suprasellar extension
T1 - 50% high, 50% low due to protein content
T2- 70% high
Gd - No enhancement
An intracystic nodule is present in 75%
Where are germinomas typically found
Pineal gland
Suprasellar
Periventricular
Typical imaging findings for cerebral abscess
Thin enhancing rim of uniform thickness.
Double rim sign:
- outer low signal rim (fibrous capsule), inner high signal rim (enhancing capsule)
What are the types of hypothalamic hamartomas?
Sessile - attached to mammillary region, near mammillary bodies
Pedunculated - attached to the tuber cinereum and projects into the suprasellar cistern
How to differentiate between spinal schwannoma Vs neurofibroma?
Both are low T1 and high T2
Schwannoma displaces nerve roots
Neurofibroma encases nerve roots
Neurofibroma - target sign (central low signal)
How does syringomyelia normally present?
Cape like loss of pain and temperature sensation along back and upper arms
What are the intradural but extramedullary tumours?
No More Spinal Masses
Neurofibroma
Meningioma
Schwannoma
Metastases
Typical imaging findings of CNS amyloidosis?
Cortical, sub cortical and cerebellar micro-haemorrhages, sparing the basal ganglia.
How can you tell the difference between amyloid micro-haemorrhage Vs hypertensive micro-haemorrhage?
Hypertensive micro-haemorrhage typically affects the basal ganglia whereas amyloid micro-haemorrhage spares the basal ganglia
MRI brain findings of Wilson’s disease?
High T2 signal in basal ganglia
Clinical presentation of Wilson’s disease?
Parkinsonism, ataxia and gait abnormalities.
Acute stroke findings on MRI?
T2 bright
Restricted diffusion
ADC values pseudo-normalise as time progresses (~2 weeks)
Most common viral encephalitis?
Herpes simplex virus encephalitis
Typical findings in HSV encephalitis?
Involvement of:
- Fronto-temporal lobes.
- Insular cortex.
- Limbic system.
Haemorrhage is frequent.
Imaging findings in Wernicke’s encephalopathy?
High T2 signal:
- mammillary bodies
- thalamus
- periaqueductal grey matter
What is Lhermitte-Duclos disease?
Dysplastic cerebellar gangliocytoma
Associated with Cowden disease
Typical imaging findings for Dysplastic cerebellar gangliocytoma
Thickening of the cerebellar cortex (Tigroid cerebellum)
High T2 signal.
No enhancement.
Dysplastic cerebellar gangliocytoma = Lhermitte-Duclos disease.
Associated with Cowden syndrome
What is Dysplastic cerebellar gangliocytoma associated with?
Cowden syndrome
What is progressive multifocal leukoencephalopathy?
AIDS related with low CD4 count
Demyelinating disease that affects the subcortical FRONTAL and PARIETO-OCCIPITAL lobes.
Intradural, intramedullary spinal neoplasms?
Energetic Astronauts Have Lively Parties
Ependymoma (60%)
Astrocytoma (33%)
Hemangioblastoma
Lymphoma
Paraganglioma
Spinal ependymoma imaging appearance?
Location cervical or upper thoracic spine (75%), within the central cord
Symmetrical widening of the cord with associated syrinx
Haemorrhage causing “cap sign”
T1 - iso
T2 - high
Gd - strong enhancement
What are spinal ependymomas associated with?
NF2
Spinal cord astrocytoma imaging appearance?
Location cervical and thoracic spine
Eccentric as they originate from cord parenchyma.
Poorly defined margins
T1 - iso
T2 high
Gd - patchy enhancement
Astrocytoma is associated with which condition?
NF1
How to differentiate between spinal cord ependymoma Vs astrocytoma?
Ependymoma adult
Astrocytoma kids
Ependymoma centrally located within cord
Astrocytoma eccentrically located within cord
Ependymoma diffuse enhancement
Astrocytoma patchy enhancement
What do cortical tubers look like on MRI?
Cortical and subcortical high T2 signal.
Rarely enhance.
What is gliomatosis cerebri?
Growth pattern if diffuse glioma that involves at least 3 lobes.
What is Lissencephaly type 2 associated with?
Congenital muscular dystrophy.
Most common association with Chiari 1 malformation?
Syrinx
