CNS Flashcards
On a CT what color is CSF?
dark
Which has more bony detail- CT or MRI?
CT scan
Which is more expensive, CT or MRI?
MRI
Which takes longer, MRI of brain or CT of brain?
MRI
Which has better soft tissue detail- MRI or CT?
MRI
Which scan should you use to rule out a bleed- MRI/ CT?
CT
What does MRI use to create images?
Magnets and radio waves
What are some risks of iodine?
Allergic rx
serious rxn
renal failure
extravasation (iodine not in blood)
What does CT contrast in the brain allow you to see?
Evaluate blood vessels and integrity of the BBB
What are some known causes of contrast induced nephrotoxicity?
Renal insufficiency (Cr >1.5) Diabetes Dehydration CV disease >70 years old Myeloma, hypertension, Hyperuricemia
If an individual is taking ______ you need to change their dosage for a CT with contrast.
Metformin
What does a history of “kidney disease” include?
Tumor, solitary kidney and transplant
________ in huge amounts can be nephrotoxic.
NSAID’s
If an individual has an allergy to iodinate contrast what can you give?
Prednisone 50 mg PO 13, 7, and 1 hour before IV contrast injection
Benadryl 50 mg 1 hour before injection
Gadolinium can cause what (rare disease)?
Nephrogenic systemic fibrosis
What are some absolute contraindications of an MRI?
cardiac pacemakers and implantable defibrillators
implantable drug pumps
vagal and boen growth stimulators
metal in eye
What is a fibrosing disease of the skin and SQ tissues that has an association between gadolinium and severe chronic renal disease?
Nephrogenic systemic fibrosis
It a patient has renal disease what should you get within 6 weeks of an anticipated contrast MRI?
Glomerular filtration rates
if someone had a stroke what should you order?
non-contrast CT or MRI
If someone has a “worst headache of their life”
non-contrast CT to rule out subarachnoid hemorrhage
For seizures what should you order?
CT w/ and w/o contrast. MRI for intractable seizures
for cranial nerve issues what should your order?
MRI with contrast
For dementia what should you order?
Non-contrasted MRI
For trauma what should you order?
Non contrasted CT then get MRI for patients who don’t improve as expected
For a person with vertigo and dizziness what should you order?
MRI with contrast
For hemorrhage what should you order?
Non contrasted CT
For atypical hemorrhage what should you order?
MRI w/ and w/o contrast
Why white matter lighter than grey?
white matter has axons with a little more fluid
What is better, 1.5 or 3 Tesla?
3 Tesla- better detail
For head trauma, what test is best to order?
CT w/o contrast
Patients with what other symptoms should undergo CT?
Headache Vomiting >60 y/o Drug/alcohol intoxication Deficits in short term memory presence of trauma above clavicles
How do most epidural hematomas occur?
With a skull fracture
how does epidural hematoma occur on CT?
Biconvex hemorrhage
If you hear a classic history of “temporary loss of consciousness followed by a lucid period then rapid clinical deterioration” what should you think?
Epidural hematoma
What artery is usually lacerated w/ epidural hematoma?
Middle meningeal artery
What does an epidural hematoma look like?
A lens
What does an subdural hematoma look like?
A crescent, tracks along the inner wall of the skull
What causes a subdural hematoma?
Occurs secondary to torn bridging cortical veins
Is a skull fracture common with subdural hematoma?
No
Where does a subdural hematoma occur?
Between arachnoid and dura mater
What causes the white in acute hemorrhage?
Methemoglobin
Someone who is very anemic (not a lot of met hemoglobin) can have what type of hematoma?
Isodense sub dural hematoma
What is blood in the cortical sulci, fissures and basilar cisterns?
Subarachnoid hemorrhage
What is the biggest thing that causes subarachnoid hemorrhage?
Aneurysm has ruptured
What can a subarachnoid hemorrhage cause?
hydrocephalus
what type pattern does subarachnoid hemorrhage have?
Branching pattern
What is a catheter directed procedure that is invasive and runs into carotid vessels and x-ray dye is injected and you take a picture of the brain?
Cerebral angiography
What are some non-invasive ways to do cerebral angiography?
CTA
MRA
What is like an x-ray but you are seeing it live?
Fluoroscopy (continuous beam)
What are some common causes of non traumatic intra parenchymal hemorrhage?
Hypertension Ruptured aneurysm or vascular malformaton Venous thrombosis Amyloidosis (patients older than 60) Collagen vascular disorders Anticoagulation therapies Tumors Cocaine use
What dose a basilar skull fracture opacify?
Sinus and mastoid air cells with blood
How can basilar skull fracture present clinically?
Otorrhea or rhinorrhea
What type fractures can present with pneumocephalus (air within cranial wall)
Sinus fracture or penetrating skull trauma
What happens in subfalcine herniation?
One side of brain moves over to the other (past the falx)
What is uncular herniation?
the innermost part of the temporal lobe, the uncus, can be squeezed so much that it moves towards the tentorium and puts pressure on the brainstem, most notably the midbrain
What happens with tonsillar herniation?
cerebellar tonsils move downward through foramen magnum
When you hear “blown pupil” what should you think?
increased intracranial pressure
Where does the 3rd cranial nerve run?
b/w posterior cerebral artery and posterior communicating artery
What is a problem where there is too much CSF coming in and not enough coming out?
hydrocephalus
How should you evaluate hydrocephalus in babies?
US
how can you fix hydrocephalus?
With shunts
Most of the time strokes are what?
Embolic
how long will cell viability be maintained w/o the available energy source needed?
2-3 minutes
You can only give thrombolytic therapy within how many hours of stroke onset?
3 hours
What type CT should you order with a stroke?
Non-contrast
What is TPA?
Tissue plasminogen activator
What is more sensitive to signs of stroke- CT or MRI?
MRI (due to diffusion)
How long does it take to see changes of acute ischemia on MRI?
within minutes on onset
How long does it take to see loss of cortical ribbon on CT?
Can occur as early as 3 hours, takes 4-6 hours
When will there be a normal CT with a stroke?
In the acute phase, within 12 hours of the stroke
What are the most common emboli origins for infarcts in the middle cerebral artery?
common carotid artery, internal carotid artery
What does a CT look like in the subacute (2-21 days) after stroke?
wedge-shaped area, low density. Loss of cortical ribbon
________ increase in the first 3 days after a stroke?
Mass effect
What are symptoms of normal pressure hydrocephalus.
Ataxia
dementia
urinary incontinence
What is treatment for normal pressure hydrocephalus?
Shunting
What is a vascular malformation w/ a risk of hemorrhage?
Arteriovenous malformations
What are 2 vascular malformations that are almost always asymptomatic?
Capillary telangiectasias
Cavernous angiomas
What is an intra-axial tumor with edema
vasogenic edema
What is the primary demyelinating disease?
Multiple sclerosis
If you see a white area at the base of the temporal lobes what should you think?
Herpes encephalitis
