CNS Pathology

Question 1

Briefly describe the nervous system.

Answer 1

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

Question 2

What are neurons?

Answer 2

nondividing, postmitotic, permanent cells

Question 3

What are glial cells?

Answer 3

facultative, mitotic (labile) cells that are capable of dividing

Question 4

What are the symptoms of CNS damage?

Answer 4

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

Question 5

How much CO does the brain receive? What about total body O2 consumption? What about body glucose consumption?

Answer 5

CO: 15%
O2: 20%
glucose: 25%

Question 6

Why are neurons and the brain vulnerable to injury?

Answer 6

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

Question 7

What occurs to the following cells after brain injury?
neurons
oligodendroglia
microglia
astrocytes
ependymal cells

Answer 7

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

Question 8

True or false: there is fibrosis after brain injury

Answer 8

false
rather, a hole is left

Question 9

What is global ischemia?

Answer 9

not enough O2 gets to the brain tissue
ex: patients with chronic heart failure or atherosclerosis

Question 10

What is cerebral infarct?

Answer 10

stroke when blood vessel bursts or leaks (hemorrhage) or when it is blocked by a blood clot, atherosclerotic plaque or embolism (ischemic)

Question 11

What is intracerebral hemorrhage?

Answer 11

bleeding in the brain, such as from a malformed vessel that is weak (aneurysm) or due to trauma

Question 12

What are the risk factors for stroke?

Answer 12

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

Question 13

True or false: there is usually a warning sign for a stroke

Answer 13

false
symptoms usually develop suddenly and without warning
symptoms could occur on and off for a day or two

Question 14

What do the symptoms of stroke depend on?

Answer 14

the area of the brain that has been damaged

Question 15

What is a common acronym used for the symptoms of stroke?

Answer 15

FAST
face drooping (one side)
arm weakness
speech difficulty
time to call 911

Question 16

What are risk factors for hemorrhagic stroke?

Answer 16

cardiovascular (ex: hypertension)
structural (ex: tumor, malformation)
lifestyle (ex: smoking, alcohol, illicit drug use)
medications (ex: antithrombotic, antiplatelet, sympathomimetics)
race
advanced age

Question 17

What are some symptoms of stroke?

Answer 17

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

Question 18

What proportion of strokes are ischemic? What about hemorrhagic?

Answer 18

ischemic: 80%
hemorrhagic: 20% (10-15% nontraumatic)

Question 19

Why does ischemia affect the brain rapidly?

Answer 19

the brain does not store glucose

Question 20

What are factors that influence the progression of CVA over time?

Answer 20

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)

Question 21

What is the pathogenesis of stroke?

Answer 21

1. local vasodilation during ischemia. At at a critical low level of
   CBF, neurons shut down, and below 10ml/100g/min will die
2. excitotoxicity: glutamine and aspartate released from region
   of ischemia, triggering influx of Ca and Na and activation of
   destructive processes leading to cell death
3. inflammation and endothelial cell reaction, leading to
   capillary plugging and increased vascular permeability
4. effects may be reversible if reperfusion within 2-4h because
   metabolism slows down in the region around the infarct
5. neuronal cell death is by necrosis and apoptosis

Question 22

What the treatment of ischemic stroke?

Answer 22

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

Question 23

What is different about tenecteplase compared to alteplase?

Answer 23

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

Question 24

What is the treatment of hemorrhagic stroke?

Answer 24

1. blood pressure control and supportive care to reduce
   intracranial pressure
2. reduce further risk (e.g. reverse anti-clotting if relevant)
   -antiplatelets=desmopressin
   -warfarin=vit K and plasma
   -heparin=protamine sulfate
   -thrombolytics=plasma

Question 25

What are some different brain injuries?

Answer 25

concussion: widespread, microscopic
contusion: localized, macroscopic bruises and/or bleeding
laceration: tearing of tissue

Question 26

What are some neck and spinal cord injuries?

Answer 26

hyperextension injury
hyperflexion injury

Question 27

How are intracranial hemorrhages classified?

Answer 27

according to location:
-epidural
-subdural
-subarachnoid
-intracerebal

Question 28

Describe intracerebral hemorrhages.

Answer 28

common complication of head trauma
rupture of intracerebral vessels
-gunshot wounds
-nontraumatic forms (e.g. stroke)
common in hematologic diseases (e.g. leukemia)

Question 29

What are some different infections of the CNS?

Answer 29

encephalitis
myelitis
meningitis
neurosyphilis
cerebral abscess
AIDS-related CNS lesions

Question 30

What is encephalitis?

Answer 30

inflammation of the brain and spinal cord usually caused by viral infection

Question 31

What are some diseases that affect the brain and spinal cord?

Answer 31

rabies
polyomelitis
herpes encephalitis
measles, mumps, rubella (causes secondary encephalitis)
mosquito-borne viruses (West Nile, La Cross, St Louis, western equine and eastern equine encephalitis)
HSV-1 most common in young adults

Question 32

Who is most at risk for encephalitis?

Answer 32

the very young and very old

Question 33

What are the symptoms of encephalitis?

Answer 33

mild cases may appear with flu-like symptoms and headache
severe cases:
-severe headache
-high fever
-drowsiness
-vomiting
-confusion
-seizures
-abnormal sensations or movements

Question 34

What are the different types of encephalitis?

Answer 34

infectious:
-inflammation occurs as a direct result of an infection, often
viral
post-infectious:
-inflammation caused by the immune system, reacts to a
previous infection or vaccine; can occur many days, weeks, or
sometimes months after initial infection
autoimmune:
-inflammation is caused by the immune system reacting to a
non-infectious cause such as tumor or antibodies
chronic:
-inflammation develops slowly over months; can be the result
of conditions such as HIV though in some cases there is no
obvious cause

Question 35

What are complications of severe encephalitis?

Answer 35

respiratory arrest
coma
death

Question 36

What is COVID brain?

Answer 36

in COVID patients the severe inflammation occurring outside the brain (lungs and elsewhere) sends signals through the BBB that activates the brain’s immune system which perpetuate inflammation
-symptoms: brain fog, impaired cognition, mood disorders, etc
-symptoms may persist for many months after the infection is
resolved and long-term effects are unknown