neuro rads head and brain Flashcards
intersection of the Frontal, Parietal, Temporal and Sphenoid bones
● Pterion:
Thinnest part of the skull
Pterion
trauma in the pterion can cause
○ Trauma here may cause epidural hematoma because the Middle meningeal artery courses through this area
abbreviations of the sutures
Squamosal = Parietal = P Occipital = O Lamboidal = L Coronal = C Sagittal = S Dotted line = anterior fontanelle
standard and customary to only get _____ sliclies with a CT of the head
axial need to request reconstructions
what are we looking for with CT
Symmetry, densities, lucencies ○ Blood: new, old - in trauma, hemorrhage ○ Ischemia, infarction, edema ○ Tumors, metastases ○ Hydrocephalus ○ Bony windows - skull fractures
how wide are
typically between 3-5 mm from the base of the skull to the vertex should be able to see the frontal sinuses
white matter on CTS
appears darker than grey
- eye
- sphenoid sinus
- temporal lobe
- mastoid oracle of the ear (pinna) can be seen outside
- Pons
- 4TH VENTRICLE
- cerebellum
A. forntal lobe
b. sylvian fissure
c
temporal love
d. suprasella cistern
e. midbrain
f. 4th vent
g. cerebullum
A. sup sagitaal sinus
b. frontal lobe
c. laterla vantricle
d. 3rd vent
e 4th vent
f cerebellum
gryi
● Grooves = elevations (worms)
sulci
● Sulci = grooves (space btw the worms)
out to in brain layers
skull
epidural
DAP
DURA
subdural
ARACHNOID
PIA
what kind of contrast do we have with CT
IV not PO
get a creatinin
what is standard ct? CON or NAH
non con is standard
when would you get a non con CT
Suspected acute CVA/TIA, focal neuro deficit
● Headache - atypical, worst of life
● Delirium* ○ If delirium has obvious cause – infection, etc…CT may not be ordered ● HA + fever: Meningitis/Abscess/Encephalitis
● Seizure - first one
● Vertigo/Dizziness w/ central sx’s*
○ Central vertigo – MRI best. CT considered if cannot obtain MRI readily
● Cancer Hx w/ new headache, HIV w/ new HA, ALOC (altered level of consciouness), focal neuro findin
○ Vomiting w/o abdominal sx’s (vomiting is often first sign of increased ICP)
○ Suspected child abuse
when do you get a CTA for a strok pt
if the person has a stroke we can interviene
ALWAYS get a non con CT for stroked person first to determine ischemic or hemorrahgic
if their stroke score if very high you get NON con first
THN you get a CTA of the head and neck
contrast makes everything look white and blood is white you don’t want to confuse a ischemic with a hemorrahgic
other than stroke pts when do we have CTA for pts
Tumors ● Brain abscess, encephalitis ● MRI now often utilized in these conditions
Hypoattenuation
Hypoattenuation (gray) ○ Edema, ischemia, ol
Hyperattenuation
white
system for CT
Check name, date, study, rotation (contrast?)
● Check symmetry ○ Midline shift (mass effect)? Effacement? ○ Effacement = narrowing, obliteration of sulci, ventricles - literally they are squished from mass effect, edema
● Hyperattenuation (white) ○ Acute bleed, calcifications, FB’s
● Hypoattenuation (gray)
○ Edema, ischemia, old blood, tumor, air
● Cisterns, CSF spaces
● Ventricle size, symmetry
● Gyri, sulci symmetric? Edema? Atrophy?
● Soft tissue, sinuses, mastoids
● Bone Windows
● *Always interpret with attending physician, confirm with radiologist
Blood Can Be Very Bad stands for
Blood, Cisterns, Brain, Ventricles, Bones/Bony Windows
blown pupil
brain can come from the foramen magnum and squeeze the 3rd ventricle and cause a blown pupil
official medical term for squished brain
effaced
effacement
“White things” without IV contrast
Abnormal = blood, calcified masses
- acute bleeding or recent bleeding is white
- tumors can be calicified
Normal = bone, typical calcifications
- pineal gland, choroid plexus, falx, basal ganglia
- therse
“White things” with IV contrast
Normal = vasculature, choroid plexus, pituitary
Abnormal = blood, tumor/mass/infection
“Dark things”:
: Cisterns, CSF spaces
Abnormal = air, edema, ischemia, encephalomalacia
- air from entery point of fracutred skull
- encephalomalacia
- defined as soft brain
- comes from brain degeneration due to lack of vascular supply
- defined as soft brain
- Artifacts: Motion, Metal - scatter effect, streaks
what can efface your sulci
edema
what type of CT would you get for head trauma
NON ct
what are you looking for with a CT trauma
Subdural Hematoma
Epidural Hematoma
Intracerebral Hemorrhage
Cerebral Contusion
indications for CT trauma
Focal neuro finding
GCS <8
Loss of consciousness
Altered level of consciousness
Skull penetration
Worsening HA, vomiting after head trauma
Post-traumatic seizure
Suspected child abuse
Coagulopathy + trauma
Significant mechanism
why can people walk around with subdural hematomas
venous hemorrhage
damage is with the bridging veins between the dura and the arachnoid
shapped like a crescent
subdural hematoma cross the medline T or F
Does not cross midline
● May cross suture lines
doesn’t wrap around the scull
what does acute blood look like on non contrast ct
acute blood is white on non-contrast head CT. Midline shift present
after about a week after a subdural hematoma
Subacute subdural – blood becomes more isodense. Midline shift present
what does a chronic subdural hematoma look like on a CT
acute on chronic subdural – new, hyperdense blood seen in old subdural. Subtle midline shift present
Epidural Hematoma occurs between wehat
Hemorrhage between dura and skull table
what shape and color do you see with epidural hematoma
Lens shape, biconvex
Hyperattenuation
why do we see regain consciousness with epidural hematoma followed by sudden death
when the bleeding occurs and accumulates you get effacement of the ventricles and eventually the brain will herniate and person will die in respiratory failure
what is characteristic of the movement of epidural hematoma
Does not cross suture lines
exapnding arterial hematoma
what is the most common hematoma
traumatic subarachnoid hematoma is the most common
Coup-contrecoup injury
= damage to the brain on both sides: the side that received the initial impact (coup) or blow and the side opposite the initial impact (countrecoup)
○ Common in boxing
Cerebral contusions:
Significant head trauma, coup-contrecoup mechanism common ○ Cerebral contusions often frontal or at periphery ○ Edema is common
who get’s a CT scan for a HA
Indications for CT in headache
○ Focal neuro findings + HA
○ ALOC + HA ○ Fever + HA
○ Vomiting (atypical) + HA
○ HA + vomiting after head trauma
○ Severe, persistent, new HA
○ “Worst HA of my life”
headache in young obese female with vision changes n/v BIH pesudotumor cerebry
Idiopathic intracranial hypertension
pseudotumor cerebri
obese woman n/v HA
how do you dx subarachnoid hemorrhage
are there white things are where are they?
Hyperattenuation (non-contrast CT scan)
● Suprasellar cisterns (Circle of Willis) or other basilar cisterns
● Sulci look white, effacement of sulci
● “Worst HA of life”
● Causes: aneurysm, AV malform tumors, trauma *
MCC
● Common to see subarachnoid hemorrhage in the Sylvian fissure
Increased Intracranial Pressure comes from
mass effect
or brain swelling cerebral edema
first thing you will see on Increased intracranial pressure CT
■ First thing you lose is normal definition of gyri/sulci ■ Infection, reactive, malignancy, toxic, anoxic (don’t have O2)
Hydrocephalus seen with Increased Intracranial Pressure
from CSF
vasogenic type cerebral edema
edema is an area of hypoattenuation that is not as dark as air and surrounds whatever is going on
● Local edema around infection, malignancy
● Vasogenic edema around acute hemorrhage
● Possible midline shift, herniation
● Predominantly affects white matter
Cytotoxic Cerebral Edema
Hypoattenuation
● Cell death after cerebral ischemia (infarct)
● Possible midline shift, herniation
● Affects both white and grey matter
● Dilated ventricles, temporal horns visible
Hydrocephalus
two types of hydrocephalus
Communicating:extraventricular cause
2) Non-communicating - intraventricular cause
describe communicating hydrocephalus
classic finding*
Decreased reabsorption of CSF
■ Acute/chronic, affects the entire ventricular system
● Hallmark = 4th ventricle enlarged
■ Normal Pressure Hydrocephalus
■ Normal Pressure Hydrocephalus is what type of hydrocephalus
Communicating - extraventricular cause
CT findings with non-communicating - intraventricular cause
Obstruction of outflow of CSF - usually d/t tumor or mass
Narrow site - 3rd or 4th vent, fora
■ 4th ventricle normal sized, sulci normal
>50 years old ○ Gait disturbance ○ Dementia ○ Urinary incontinence
classic presentation of
Normal Pressure Hydrocephalus
Special hydrocephalus – Communicating type
Normal Pressure Hydrocephalus is caused by
Dilated ventricles out of proportion to atrophy
Giant ventricle but normal sulci
Diffuse prominence of sulci, ventricles
● Space between edges of brain and skull table
● Normal CSF production, absorption
● Incidental finding, chronic (happens over time)
all characteristic of
Cerebral Atrophy
Cerebral Atrophy seen most commonly
dementia (Alzheimer’s), alcoholism (cerebellar)
higher incidence of subdural hematoma
what window period might we see a falsely negative CT with a CVA
<6hrs sx’s, CT often falsely negative if ischemic ○ MRI more sensitive early on if ischemic
Hemorrhagic CVA →
call neurosurgeon
may have to have surgery to stop the bleed
Ischemic CVA (negative CT)
call neurologist for stent or TPA
Acute: hyperattenuation: collections of blood seen without a shift and with edema
could be a hemorrhagic stroke
what spots of the brain does hemorrahgic stroke favor
● Favor basal ganglia, thalamus, pons, cerebellum
Local vasogenic edema
● Effacement of gyri/sulci & midline shift common
● Risks: HTN, coagulopathy, stimulants (cocaine, meth
) ● Less common than ischemic; more morbidity/mortality
Hemorrhagic CVA
more sensitivity with this type of imaging in ischemic CVA
● MRI more sensitive early
Vascular watershed” distribution of ischemia seen in
ischemic CVA
4 subtle CVA signs
- Hyperdense vessel sign
- Loss of “insular ribbon” - grey matter stripe or interface with white matter
- Lentiform nucleus and caudate nucleus are not distinctly visible
- Effacement of sulci
lacunar infarcs
very very deep
seen as a deep area of hypoattunation
DM, HTN pts, not horribly insignificant unless there are many
occur with tiny vessels
intra-axial tumor is
within brain parenchyma
■ Glioma, astrocytoma, etc
extra axial tumors on CT are located
outside of brain itself
■ Meningioma, acoustic neuroma
Big, round, multiple, enhance w/ contrast
METS
Glioma and astrocytoma
are both what type of tumor (location)
intra axial
sxs of braintumors
HA, vomitting, altered mental status or nothing
neurocystocitosis !
first time seizure in an otherwise well person in an endemic area casued by a worm in the brain
cysticercosis cyst with edema
parascitic agent
Weighting: T1 or T2? ■ CSF is WHITE on _______
Weighting: T1 or T2? ■ CSF is WHITE on T2-weighted image
indications for MRI
More sensitive than CT for cerebellar lesions, central vertigo, multiple sclerosis (test of choice along with an LP), diffuse axonal injury, tumors
○ *Need an MRI for the diagnosis of multiple sclerosis → looking for MS plaques (not found on CT)
seen as plawues with MRI also need a lumbar puncture
EDH is usually due to injury to the _______ secondary to an _______
EDH is usually due to injury to the middle meningeal artery or vein secondary to an associated skull fracture. Unlike subdural hematoma, EDHs do not cross suture lines, but can cross the tentorium.
high density, extra-axial, biconvex lens- shaped mass lesion usually in the temporal-parietal region of the brain
EDH
MCC of SAH
Rupture of an aneurysm is the most common cause of a SAH (50-70%)
Suprasellar cisterns (Circle of Willis) or other basilar cisterns
● Sulci look white, effacement of sulci
SAH
worst ha of my life
Rupture of an aneurysm is the most common cause of a SAH (50-70%) but not the only cause as trauma these tow things can also produce a SAH
, arteriovenous malformations or breakthrough of an intraparenchymal bleed can also produce subarachnoid hemorrhage.
a shift of the frontal horns of the lateral ventricles (o the right of midline (dotted line), would indicats the presence of__________
a shift of the frontal horns of the lateral ventricles (o the right of midline (dotted line), would indicats the presence of subfalcine herniation.
Communicating hydrocephalus is due to abnormalities that inhibit _______, most often at the level of the _______and is usually treated with a ventricular shunt.
Communicating hydrocephalus is due to abnormalities that inhibit the resorption of cerebrospinal fluid, most often at the level of the arachnoid villi and is usually treated with a ventricular shunt.
the thalami are on either side of the ____, and the caudate nuclei (C) are on either side of the __________
the thalami are on either side of the third ventricle (black arrow), and the caudate nuclei (C) are on either side of the frontal horns of the lateral ventricles.
Headache in young, obese female with vision changes, n/v
Benign Intracrainial Hypertension or Pseudotumor Cerebri
Hypoattenuation from encephalomalacia is typically seen as this type of edema
Cytotoxic Cerebral Edema
Dilated ventricles, temporal horns visible seen with this type of edema
Hydrocephalus
CSF build up in the brain
= non communicating Hydrocephalus
you can tell because the fourth ventricle is not enlarged
diffuse prominent sulci and ventricles are characteristic of
cerberal atrophy
deep in the brain
HTN
DM
