Day 1 review Flashcards
• Faster and cheaper • Radiation • Better for bone, blood and trauma • Bone and blood – bright • Fat and air – dark higher resolution but requires radiation and dye
CT
- Slower and more expensive
* Better for soft tissue
MRI
– fat and brain are bright; csf and air are dark
• T1
– CSF and fat are bright; air and bone are dark
• T2
• MRA – no dye or radiation, good for
aneurysms and stenosis
Use ___ for acute stroke to evaluate for hemorrhage
CT:
• Hemorrhage will be bright
• CTA to evaluate source of bleeding
• No findings in early acute ischemic stroke
is most sensitive for acute stroke findings
Soft tissue like spinal cord
• MRI
- Extracellular
- White matter
- Tumor, abscess, hematoma, contusion
- Inflammatory, chemo and cytokines
- Breakdown of BBB in tumor,
- Responds to steroids
Vasogenic
Intracellular
• Gray matter
• Ischemia, meningitis, trauma, hepatic enceph.
• Cellular swelling from sodium (and then water)
• Dysfunctional membrane pumps
• Does not respond to steroids
Cytotoxic
• Subfalcine hernation – side to side, hemispheric lesion with a_____ infarct
ACA
Transtentorial/uncal – temporal lobe pushes through onto brainstem : what are the 3
PCA infarct, CNIII compression, Duret hemorrhage
– through foramen magnum • Respiratory arrest and death
Tonsillar hernation
- Ventricular system open with Decreased absorption at arachnoid granulations
- Meningitis, hemorrhage, thrombosis
- Or CSF overproduction
- Choroid plexus tumor
Communicating hydrocephalus
- Obstruction of ventricular system
* Tumor, aqueductal stenosis, thickened meninges
Noncommunicating hydrocephalus
Common location of contusions
orbital and temporal regions, crests of gyri
What happens in acute contusions?
see superficial hemorrhage and edema
What happens in Chronic contusions
– cavitated, macrophages with hemosiderin, fibrillary astrocytes
____on the injury side,_____ on the opposite
Coup
contracoup
- axonal shearing in white matter
- Petechial hemorrhages
- Maximum deficit at onset
Diffuse Axonal
- Skull fracture (high speed)
- Accumulates slowly (lucid interval)
- Always life threatening
- Middle meningeal artery
- Convex appearance
Epidural hematoma
- Any trauma, common in elderly
- Can present acute, subacute or chronic
- Bridging veins
- Can become chronic
- Concave appearance
Subdural hematoma
- ______ worse than hypoxia alone
- Reduced O2 delivery to tissues,
- If low BP, worst in ________
Ischemia
watershed/borderzone areas
AReas susceptible to ischema
- Hippocampus CA1, cortical lamina 3-5, cerebellar purkinje cells most sensitive
- Neurons>oligodendrocytes>astrocytes
- Red is dead (dead neurons appear red after ischemia)
- soft swollen brain, loss of G/W distinction
* 8-12hr Red neurons; up to 48hr neutrophils
• Acute focal ischemia
- liquefactive necrosis
* Macrophages, necrotic tissue, reactive astrocytes, vascular proliferation
Subacute focal ischemia
• Cavitation, glial scar
presentes in Chronic focal ischemia
- Bleeding can occur after an infarct if reperfusion into ischemic brain
- More common in :
embolic stroke, cortical lesions
***Tends to be petechial blood with surrounding ischemic brain edema
Describe Large vessel atherosclerosis
- Carotid bifurction, MCA origin, basilar origin
- Plaque rupture causes thrombosis
- Complete vessel occlusion can cause stroke if collateral circulation isn’t adequate
Small vessel hyaline arteriolosclerosis
- Seen in HTN and DM
- Small perforator vessels (basal ganglia, Internal capsule, thalamus, pons, white matter)
- Lacunar strokes 1-1.5cm
Embolism
• Tend to go to distal branches at cortex with ____ Most common vessel
MCA
*Shower of emboli can happen A/P, L/R
Embolism from cardiac source cause by:
• Atrial fibrillation, valvular disease, MI with akinetic segment • Endocarditis
Artery to artery embolism
• Carotid plaque, intracranial stenosis
another source of embolism
venous clotting,leads to bleeds from back pressure in draining veins :Parasagittal bleeds
CVT
Hypertension causing intercerbral hemorrhage
• Causes _______at small penetrating vessels (same ones that cause lacunes)
hyaline arteriolosclerosis
areas susceptible to hyaline arteriolosclerosis causing intercerbral hemorrhage
• Basal ganglia, pons, cerebellum, thalamus, IC and white matter
How does intracerebral hemorrhage differ from hemorrhagic infarct?
not having surrounding infarcted tissue
• Large clot (hematoma) rather than petechial blood
- AVM
- Congenital abnl of vessels with arterio-venous direct connection
- High bleed risk
- Presents with seizures, bleeding, focal deficit
AVM: intracerebral hemorrhage
- Lobar hemorrhage
- elderly
- Beta amyloid on congo red stain
Amyloid angiopathy: intracerebral hemorrhage
- Develop with age, medial defect is congenital
- Bifurcations of circle of willis, ACOM>MCA>ICA>basila
- Worse with smoking ,HTN
Berry aneurysm; subarachnoid hemorrhage
