CNS Pathology Flashcards
Briefly describe the nervous system.
consists of highly specialized functional units
CNS is protected from mechanical injury by bones of the skull and vertebrae
CNS is separated from remainder of body by meninges and by BBB
brain and spinal cord are surrounded by CSF
What are neurons?
nondividing, postmitotic, permanent cells
What are glial cells?
facultative, mitotic (labile) cells that are capable of dividing
What are the symptoms of CNS damage?
symptoms result from dysfunction of or loss of function of neurons
-specific loss of function is associated with the area damaged
-global issues can arise from more diffuse injury
How much CO does the brain receive? What about total body O2 consumption? What about body glucose consumption?
CO: 15%
O2: 20%
glucose: 25%
Why are neurons and the brain vulnerable to injury?
high activity level and specialization as well as its fatty nature
many organic toxins are fat-soluble
brain also contains high concentrations of sulfur-containing amino acids which bind toxic heavy metals
What occurs to the following cells after brain injury?
neurons
oligodendroglia
microglia
astrocytes
ependymal cells
neurons:
-axon and/or cell body may become swollen
-rapid death results in phagocytosis
-axons may be regenerated
oligodendroglia:
-these myelinating cells do not regenerate
microglia:
-transform into phagocytic cells once activated by chemotactic
factors
astrocytes:
-undergo hypertrophy and hyperplasia=gliosis
ependymal cells:
-these cells line the ventricles and do not regenerate
True or false: there is fibrosis after brain injury
false
rather, a hole is left
What is global ischemia?
not enough O2 gets to the brain tissue
ex: patients with chronic heart failure or atherosclerosis
What is cerebral infarct?
stroke when blood vessel bursts or leaks (hemorrhage) or when it is blocked by a blood clot, atherosclerotic plaque or embolism (ischemic)
What is intracerebral hemorrhage?
bleeding in the brain, such as from a malformed vessel that is weak (aneurysm) or due to trauma
What are the risk factors for stroke?
high blood pressure (#1 risk factor)
atrial fibrillation
diabetes
family history
high cholesterol
increasing age (esp. >55)
people with heart disease or poor blood flow in their legs
overweight, drinking heavily, poor diet, smoking, drugs, etc
True or false: there is usually a warning sign for a stroke
false
symptoms usually develop suddenly and without warning
symptoms could occur on and off for a day or two
What do the symptoms of stroke depend on?
the area of the brain that has been damaged
What is a common acronym used for the symptoms of stroke?
FAST
face drooping (one side)
arm weakness
speech difficulty
time to call 911
What are risk factors for hemorrhagic stroke?
cardiovascular (ex: hypertension)
structural (ex: tumor, malformation)
lifestyle (ex: smoking, alcohol, illicit drug use)
medications (ex: antithrombotic, antiplatelet, sympathomimetics)
race
advanced age
What are some symptoms of stroke?
change in alertness (sleepy, unconscious, coma)
changes in hearing, taste, sensation of pain/pressure/temp
problems with eyesight
confusion or loss of memory
difficulty swallowing, writing, or reading
vertigo
lack of control over bladder, bowels, balance or coordination
muscle weakness (usually one side)
trouble speaking and walking
What proportion of strokes are ischemic? What about hemorrhagic?
ischemic: 80%
hemorrhagic: 20% (10-15% nontraumatic)
Why does ischemia affect the brain rapidly?
the brain does not store glucose
What are factors that influence the progression of CVA over time?
duration of ischemia (longer is worse)
collateral circulation (more is better)
blood pressure–>affects overall cerebral perfusion
hematological factors (prone to clotting=bad)
temperature (cooler is better, slows down brain metabolism and extent of injury)
glucose metabolism (more is better)
What is the pathogenesis of stroke?
- local vasodilation during ischemia. At at a critical low level of
CBF, neurons shut down, and below 10ml/100g/min will die - excitotoxicity: glutamine and aspartate released from region
of ischemia, triggering influx of Ca and Na and activation of
destructive processes leading to cell death - inflammation and endothelial cell reaction, leading to
capillary plugging and increased vascular permeability - effects may be reversible if reperfusion within 2-4h because
metabolism slows down in the region around the infarct - neuronal cell death is by necrosis and apoptosis
What the treatment of ischemic stroke?
at ER: labwork, CT scan
tPA: 0-3 vs 3-4.5hrs (alteplase, IV r-TPA)
-CI relate to risk of bleeding, including HTN
-ensure no intracranial hemorrhage
-control bp (labetalol or enalapril if bp > 185/110)
intracranial vascular imaging after tPA
stenting considered when tPA contraindicated or ineffective
What is different about tenecteplase compared to alteplase?
single bolus
longer duration due to less inactivation by PAI
thought to work better for larger clots
immediate recovery not better but possibly fewer bleeds
What is the treatment of hemorrhagic stroke?
- blood pressure control and supportive care to reduce
intracranial pressure - reduce further risk (e.g. reverse anti-clotting if relevant)
-antiplatelets=desmopressin
-warfarin=vit K and plasma
-heparin=protamine sulfate
-thrombolytics=plasma
