CTC Neuro Flashcards
Pattern of myelination in the brain.
Inferior to superior
Posterior to anterior
Central to peripheral
Sensory then motor.
Subcortical last.
At birth, the brainstem and posterior limb of internal capsule are myelinated.
Immature brain is opposite T1 and T2.
The anterior and posterior pituitary are bright at birth.
How does the corpus callosum develop?
Front to back, then rostrum.
Order of development of the sinuses?
Maxillary, Ethmoid, Sphenoid, and frontal last.
Contents of foramen ovale
V3 and accessory meningeal artery
Contents of inferior orbital fissure
V2
What does NOT run through the cavernous sinus?
CN2
V3
What are the branches of the external carotid artery?
Some Administrators Like Fucking Over Poor Medical Students
Superior Thyroid Ascending Pharyngeal Lingual Facial Occipital Posterior Auricular Maxillary Superficial Temporal
Segments of the ICA
Cervical Petrous Lacerum - adjacent to Meckels cave Cavernous - HTN aneurysm Clinoid Opthalmic - Aneurysm formation Communicating - CN III palsy
Location of CN3 in COW?
Between PCA and SCA
Where does the Anaterior Choroidal Artery arise?
MCA
What are the superficial and deep cerebral veins?
Superficial: Superficial cerebral veins Superior anastomic vein of Trolard Inferior anastomotic vein of Labbe Superficial middle cerebral veins
Deep:
Basal Vein of Rosenthal
Vein of Galen
Inferior Petrosal Sinus
What is the relationship of the Veins of Labbe and Trolard?
Share drainage of the same territory - one gets bigger, the other gets smaller.
Vein of Labbe: Large draining vein, connecting the superficial middle vein and the transverse sinus
Vein of Trolard: Smaller (usually) vein, connecting the superficial middle vein and sagittal sinus.
Basal Vein of Rosenthal: Deep vein that passes lateral to the midbrain through the ambient cistern and drains into the vein of Galen. Courses similar to the PCA.
Vein of Galen: Big vein formed by the union of two internal cerebral veins.
What to think of with CN3 and CN6 palsies?
CN3: PComm Aneurysm
CN6: Increased ICP.
Cause of non-obstructive hydrocephalus?
Something that produces CSF - Choroid plexus papilloma.
What is Hurst Disease?
Acute Hemorrhagic Leukoencephalitis - fulminant form of ADEM with massive brain swelling and death. Hemorrhagic part is only seen on autopsy.
What is PRES?
Posterior Reversible Encephalopathy Syndrome
HTN or chemotherapy.
Asymmetric cortical and subcortical white matter edema (usually in parietal occipital regions). Does NOT diffusion restrict.
What does Osmotic Demyelination Syndrome look like?
T2 bright in the central pons (spares the periphery).
Can also have extra-pontine presentation involving the basal ganglia, external capsule, amygdala, and cerebellum.
What does Wernicke Encephalopathy look like?
Thiamine deficiency.
Enhancement of the mammillary bodies.
Also T2/FLAIR signal in the bilateral medial thalamus and periaqueductal gray.
What does Carbon Monoxide Poisoning Look like?
CT hypodensity/T2 bright GLOBUS PALLIDUS
Carbon monoxide causes “globus” warming.
What is Marchiafava-Bignami?
Swelling and T2 bright signal affecting the corpus callosum - typically beginning in the body, then genu, and lastly splenium).
Will involve the central fibers and spare the dorsal and ventral fibers (“sandwich sign” on sagittal imaging).
What does Methanol Poisoning look like?
Optic nerve atrophy
Hemorrhagic PUTAMEN and subcortical white matter necrosis.
What is Disseminated Necrotizing Leukoencephalopathy?
Severe WM changes which demonstrate ring enhancement - classically with leukemia patients undergoing radiation and chemotherapy - can be fatal.
Can get T2 effects acutely in white mater that can progress to atrophy with chemotherapy. Enhancement or mass effect is rare unless its very severe. Children receiving both radiation and chemotherapy can sometimes develop calcifications.
Findings of Alzheimers
Hippocampal atrophy (first) out of proportion to the rest of the brain atrophy. Temporal horn atrophy >3 mm.
Findings in Lewy Body Dementia
Similar clinical picture to Dementia with Parkinsons, but dementia comes first.
Hippocampi remain normal in size and you have some decreased FDG uptake in the lateral occipital cortex with sparing of the mid posterior cingulate gyrus (Cingulate Island Sign).
What is Binswanger Disease?
Subcortical leukcoencephalopahy that affects older people (55 and up), strongly associated with HTN.
Form of small vessel vascular dementia. Spares the subcortical U fibers.
PET findings in Alzheimer, Multi-infarct, Dementia with Lewy Bodies, Picks/Frontotemporal/Depression and Huntingtons
Alzheimers - Low posterior temporoparietal cortical activity - Identical to Parkinson Dementia
Multi-Infarct - Scattered areas of decreased activity - Lyme, HIV, and Vasculitis are mimics
Dementia with Lewy Bodies - Low in lateral occipital cortex - Preservation of the mid posterior cingulate gyrus (Cingulate Island Sign)
Picks/Frontotemporal/Depression - Low Frontal Lobe - Depression is a mimic
Huntingtons - Low activity in caudate nucleus and putamen.
MC TORCH infection?
CMV - Toxo is 2nd MC.
Likes the germinal matrix and causes periventricular tissue necrosis. Periventricular calcifications.
CMV has the highest association with polymicrogyria.
What is Toxoplasmosis?
2nd MC TORCH - CMV is MC. Cat shit.
Calcification pattern is more random and affects the basal ganglia. Frequency increased in the third trimester (but only a problem in the first two).
Hydrocephalus.
What is CNS Rubella?
Calcs are less common than in other TORCH infections.
MRI: Focal high T2 signal might be seen in white matter (related to vasculopathy and ischemic injury).
Peds HSV CNS infection?
HSV-2
Unlike adults, does not primarily affect the limbic system, but instead affects the endothelial cells resulting in thrombus and hemorrhagic infarction with resulting encephalomalacia and atrophy.
What is peds HIV CNS infection?
Not a TORCH, but does occur during pregnancy, at delivery, or through breast feeding.
Brain atrophy predominantly in the frontal lobes.
May have faint BG enhancement seen on CT and MRI preceding the appearance of BG calcification.
CNS TORCH infections
CMV = MC, periventricular calcs, polymicrogyria Toxo = Hydro, BG calcs. Rubella = Vasculopathy/Ischemia. High T2 signal - less calcs HSV = Hemorrhagic Infarct and lead to bad encephalomalacia (hydranencephaly) HIV = Brain atrophy in frontal lobes.
MC opportunistic infection in AIDS
Toxo - T1 dark and T2 bright, ring enhancing lesions - NOT diffusion restricting. Thallium cold.
MC fungal infection is Cryptococcus
HIV Encephalitis vs PML?
HIV: CD4 <200. Symmetric increased T2/FLAIR signal in the deep white matter. T1 will be normal. Lesions will not enhance. May be associated brain atrophy. Spares the subcortical U-fibers.
PML: JC virus. CD4<50. Single or multiple scattered hypodensities, with corresponding T1 hypointensity. T2/FLAIR hyperintensities out of proportion to mass effect. Involve the subcortical U-fibers. Asymmetry helps differentiate from HIV encephalitis.
MRI findings of AIDS encephalitis, PML, CMV, Toxo, and Cryptococcus
AIDS Encephalitis: Symmetric T2 bright
PML: Asymmetric T2 bright, T1 dark
CMV: Periventricular T2 bright, Ependymal enhancement
Toxo: Ring enhancement, Thallium cold
Cryptococcus: Dilated perivascular spaces, basilar meningitis.
Difference between TB meningitis and sarcoid
Enhancement of the basilar meninges with minimal nodularity. Can have dystrophic calcs.
Can have hydrocephalus with TB.
What is Limbic Encephalitis?
Paraneoplastic syndrome - usually small cell lung cancer. Not an infection.
Looks similar to HSV (titer will be negative). Do lung cancer screening.
What does West Nile look like?
T2 bright basal ganglia and thalamus with corresponding restricted diffusion. Hemorrhage is sometimes seen.
Findings of CJD?
DWI showing cortical gyriform restricted signal - most sensitive sign.
Hockey stick sign/Pulvinar Sign - restricted diffusion in the dorsal medial thalamus (which looks like a hockey stick).
Series of MRs or CTs showing rapidly progressive atrophy.
What is Neurocysticercosis?
Undercooked pork. Tinea Solium. Involvement of the subarachnoid space over the cerebral hemispheres, basal cisterns, brain parenchyma, and ventricles. Involvement of the basal cisterns carries the worst outcome.
4 Stages:
Vesicular - Thin walled cyst (iso-iso T1/T2 + no edema)
Colloidal - Hyperdense Cyst (bright-bright T1/T2 + edema)
Granular - cyst shrinks, wall thickens (less edema)
Nodular - small calcified lesion (no edema)
Peds Supratentorial vs Infratentorial Tumors
Supratentorial
Astrocytoma (including GBM), PXA, PNET, DNET
Infratentorial
JPA, Medulloblastoma, Ependymoma, Ependymoma, Braainstem Astrocytoma
Adults Supratentorial vs Infratentorial Tumors
Supratentorial
Mets ++
Astrocytoma (including GBM)
Oligodendroglioma
Infratentorial
JPA
Hemangioblastoma
Skull base tumors
Chordoma (midline) Chondrosarcoma (off midline) Esthesioneuroblastoma Sinonasal Carcinoma Mets Lymphoma Paraganglioma
Sella/Parasellar Tumors
Sarcoid Aneurysm Adenoma Rathke's Cyst Teratoma Craniopharyngioma Hamartoma Hypothalamic Glioma Meningioma Optic Nerve Glioma
Intraventricular Tumors
Ependymoma Subependymoma Choroid Plexus Papilloma Central Neurocytoma Colloid Cyst Meningioma Giant Cell Astrocytoma
CP Angle Tumors
Schwannoma
Meningioma
Epidermoid
Arachnoid Cyst
Pineal Region Tumors
Pineocytoma Pineoblastoma PNET Tectal Glioma Meningioma Dermoid Germinoma
What are the “cortically based” tumors?
Most intra-axial tumors are located in the white matter.
Cortically based (DOG):
Dysembryoplastic Neuroepithelial Tumors (DNET)
Oligodendroglioma
Ganglioglioma
Tumor syndromes
NF1: Optic gliomas and astrocytomas
NF2: MSME: Multiple schwannomas, meningiomas, ependymomas
TS: Subependymal tubers, IV giant cell astrocytomas
VHL: Hemangioblastomas
What are the low grade intraxial tumors that enhance?
Ganglioglioma and juvenile pilocytic astrocytoma
Extraxial tumors will enhance and tumors that are high grade enough to disrupt the BBB.
Hemorrhagic mets
MR and CT
Melanoma
Renal
Carcinoid/Choriocarcinoma
Thyroid
What is Turncot Syndrome?
GI polyps and Medulloblastoma and GBMs.
What is associated with an Oligodendroglioma?
1p/19q deletion - has a better outcome.
Calcifies 90% of the time. MC in frontal lobe and “expands the cortex” - cortical infiltration and marked thickening.
Hormones in the anterior and posterior pitutitary
FLAT-PEG
Anterior:
FSH, LSH, ADH, TSH
Posterior:
Prolactin, Endorphins, GSH
What drug can result in Pituitary Apoplexy?
Bromocriptine (or other prolactin drugs)
What is a Craniopharyngioma?
Two types: Papillary (adults) and Adamantinomatous.
Papillary type in adults are solid and do not have calcifications. Recur less frequently than tha Adamantinomatous form (b/c they are encapsulated). Strongly enhance.
Adamantinomatous - calcified. Recur. “Machinery oil”
What is a Hemangiopericytoma?
Soft tissue sarcoma that can mimic an aggressive meningioma b/c they both enhance homogeneously. Can mimic a dural tail, with a narrow base of dural attachment.
Won’t calcify or cause hyperostosis, but will invade the skull.
What is a Desmoplastic Infantile Ganglioglioma/Astrocytoma “DIG”?
Large cystic tumors that like to involve the superficial cerebral cortex and leptomeninges. Have a better prognosis than Atypical Teratoma/Rhabdoid tumors.
Always arise in the supratentorial location usually involving more than one lobe (frontal and parietal MC), and usually present before first birthday.
Buzzword is “rapidly increasing head circumference”.
Brain mets in a kid
Neuroblastoma - like the bones and the dura.
Characteristically involves the posterolateral part of the orbit where the frontal bone and greater wing of the sphenoid meet (EG can do this too).
What is a Juvenile Pilocytic Astrocytoma?
Cyst with a nodule in a kid - nodule will enhance. Posterior fossa (or optic chiasm).
What is a DNET?
Dysembryoplastic Neuroepithelial Tumors
Kid with drug resistant seizures. Temporal lobe. Focal cortical dysplasia is seen in 80%.
Hypodense on CT and MRI will be little if any surrounding edema. High T2 signal “bubbly lesion.”
What is a PXA?
Pleomorphic Xanthroastrocytoma
Superficial tumor ALWAYS supratentorial and usually involves the temporal lobe.
Cyst with a nodule. Usually no peritumoral T2 signal. Frequently invades the leptomeninges. Look like a Desmoplastic Infantile Glioma but not in an infant.
What is a PNET?
Primitive Neuroectodermal Tumor
Same histo as a medulloblastoma. Supratentorial (deep white matter). Classically very heterogeneous and known for metting outside the CNS.
What is Garlin Syndrome?
Medulloblastoma, look for thick dural calcs.
Get basal cell skin cancer after radiation and have odontogenic cysts.
What are the 3 tumors associated with the Pineal Gland?
Germinoma- most common.
Pineocytoma
Pineoblastoma
What is a Pineal Germinoma?
MC pineal tumor. Boys.
Precocious puberty may occur from secretion of hCG. Mass containing fat and calcifications with variable contrast enhancement. Heterogeneous on T1 and T2 (b/c of mixed components)
“Engulfed” calcifications
What is a Pineocytoma?
Rare in childhood. Well-circumscribed, and non-invasive. Tend to be more solid, and the solid component do typically enhance.
“Exploded” calcifications
What is a Pineoblastoma?
Does occur in childhood. Unlike pineocytoma high invasive - like a PNET of the pineal gland.
Associated with retinoblastomas. Heterogeneous and enhance avidly.
“Exploded” calcifications
Brain tumor syndromes
NF-1: Optic nerve gliomas
NF-2: MSME: Multiple schwanomas, meningiomas, and ependymomas
VHL: Hemangioblastoma (brain and spine)
TS: Subependymal Giant Cell Astrocytoma, Cortical tubers
Nevoid Basal Cell Syndrome (Gorlin): Medulloblastoma
Turcot: GBM, Medulloblastoma
Cowdens: Lhermitte-Dulcos (Dysplastic cerebellar gangliocytoma).
Things associated with LeFort 1, 2, and 3
LeFort 1: Lateral Nasal Aperture
LeFort 2: Inferior Orbital Rim and Orbital Floor
LeFort 3: Zygomatic Arch and Lateral Orbital Rim/Wall
Watershed infarcts in a kid
Moyamoya
What is “Fogging” with strokes?
Phase in the evolution of stroke when the infarcted brain looks like normal tissue. Seen around 2-3 weeks post infarct. Usually noncon CT, but T2 can have similar effect. Can see infarct with IV contrast.
Things that restrict diffusion other than stroke?
Bacterial Abscess CJD (cortical) Herpes Epidermoids Hypercellular brain tumors (classic is lymphoma) Acute MS lesions Oxyhemoglobin Post Ictal States
What is Venous Infarct?
Higher risk for hemorrhagic transformation.
Dehydration in babies. Adults- coagulopathies (protein C and S) and OCPs. MC site is the sagittal sinus.
Tend to have heterogeneous restricted diffusion. Can result in vasogenic edema that eventually progresses to stroke and cytotoxic edema.
Arterial stroke = cytotoxic edema
Venous stroke = vasogenic edema + cytotoxic edema.
What are the stigmata of chronic venous thrombosis?
Development of dural AVF, or increased CSF pressure from impaired drainage.
What are the subtypes of aneurysms?
Fusiform- Associated with PAN, connective tissue disorders, or syphilis. MC affect the posterior circulation. May mimic a CPA mass.
Pedicle Aneurysm - associated with AVM. Found on the artery feeding the AVM. May be higher risk to bleed than the AVM itself (b/c of high flow)
Blister Aneurysm - Broad-based at a non-branch point (supraclinoid ICA is MC). Angio is often negative.
Infundibular Widening - Not a true aneurysm, but a funnel-shaped enlargement at the origin of the PComm at the junction with the ICA. “Not greater than 3mm.”
