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532- Neuroscience - Exam 2 > Cereberovascular Disorders > Flashcards

Cereberovascular Disorders Flashcards

0
Q

What is Arterio-Venous (A-V) malformation?

A

A-V malformation is a tangle of thin-walled blood vessels that shunt blood directly from arterial to venous circulation with no capillary bed to allow for gas exchange.

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1
Q

What are the five Cerebrovascular disorders we covered in this section?

A
  1. Arterio-Venous malformation
  2. Berry aneurysm
  3. Vertebrobasilar insufficiency (VBI)
  4. Transient ischemic attack (TIA)
  5. Cerebral vascular accident (CVA) - stroke
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2
Q

A-V malformation is commonly found along with what other events?

A
  1. Intracerebral hemorrhage

2. Focal seizure activity

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3
Q

Is treatment for A-V malformation dangerous? What does treatment typically involve?

A

A-V malformation treatment is dangerous and complicated.

It involves application of vascular clips or embolization of the vessel (deliberately injecting the chemical emboli to deliberately block vessels).

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4
Q

What is a berry aneurysm?

How can a berry aneurysm be fatal?

A

A berry aneurysm is a weakening in the wall of a vessel. The thin wall balloons out under pressure.

The vessel can eventually leak or rupture, causing intracranial hemorrhage.

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5
Q

Where are the majority of berry aneurisms located?

A

Over 90% of berry aneurisms are in the anterior part of the circle of Willis. The remaining are in the vertebrobasilar system.

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6
Q

What is vertebrobasilar insufficiency (VBI)?

A

VBI is a set of systems associated with decreased bloodflow to posterior sections of the brain, such as the medulla, cerebellum, and posterior cerebral hemisphere.

VBI can occur with hyperextension or rotation of the neck which may put torsion on the vertebral artery.

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7
Q

What are some clinical symptoms of vertebrobasilar insufficiency (VBI)?

A

Clinical symptoms include light headedness, vertigo, nystagmus, and loss of balance.

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8
Q

What is transient ischemic attack (TIA)? What causes TIA?

TIA is a huge risk factor for what other cerebrovascular disorder?

A

Transient ischemic attack is a temporary stoppage of bloodflow to a part of the brain.

TIA is caused by minute emboli or blood clot arising from plaques that temporarily block brain arteries but then are broken down.

TIA is a huge risk factor for a stroke. (Nicknamed a “mini-stroke.)

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9
Q

What is a cerebral vascular accident? What causes CVA?

How many individuals are affected by CVA a year?

A

Cerebral vascular accident (or stroke) is a disruption of blood supply to the brain resulting in permanent impairment of functions due to:

  1. Blood vessels being plugged by a thrombus or embolus
  2. Hemorrhage.

Every year there are around 795,000 new victims.

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10
Q

What are the two types of CVA? Which type is more common?

A
  1. Occlusive CVA (88%)
    - Thrombus
    - Embolus
  2. Hemorrhagic CVA (12%)
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11
Q

What are the differences between the two types of occlusive CVA’s?

A
  1. Thrombus
    - A locally formed blood clot, usually in a narrow segment of a vessel
  2. Embolus
    - An obstruction formed by a blood clot, tumor cell, plaque fragment, or fat that travels to a brain artery and gets stuck at a narrow segment of a vessel.
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12
Q

What artery is the most common site of brain infarction of the embolic type? Why?

A

The middle cerebral artery is the most common site of embolic brain infarction because it is a direct continuation of the internal carotid artery.

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13
Q

What is hemorrhagic CVA? What structures are typically affected?

Individuals with what cardiovascular condition are most likely to have a hemorrhagic CVA versus other forms of CVA?

A

Hemorrhagic CVA (12% of total CVA’s) is a brain infarction caused by a thin-walled vessel hemorrhage.

It typically affects deep nuclei (caudate, globus pallidus, putamen).

Individuals with hypertension are typically those affected by a hemorrhagic CVA versus a occlusive CVA.

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14
Q

Type II diabetes is one of the most common risk factors of which cerebrovascular disorder?

What is another name for Type II diabetes?

A

Cerebral vascular accident (stroke)

Type II diabetes is also referred to as Diabetes mellitus

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15
Q

What are some risk factors that contribute to CVA?

A
  1. Age > 55
  2. Family history of CVA
  3. Hypertension
  4. Heart/Vascular disease (atrial fibrillation, atherosclerosis, vasculitis, congential vascular lesions, and blood clotting abnormalities)
  5. Diabetes
  6. Smoking
  7. Previous transient ischemic attack (TIA)
  8. Carotid stenosis
  9. Tumors (which can cause embolus formation)
  10. Dehydration; malnutrition
  11. Trauma
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16
Q

What are some of the conditions that are consequences of CVA?

A
  1. Voluntary movement dysfunction
  2. Sensory loss
  3. Speech/language/swallowing deficits
  4. Decreased cerebration (memory, emotion, confusion, lethary)
  5. Abnormalities in vital functions
  6. Abnormalities related to special senses
17
Q

What are examples of voluntary movement dysfunction that can occur as a result of CVA?

A

Motor cortex or motor pathways are affected

A. Paresis - weakness
B. Paralysis - complete loss of motor function (hemiplegia is loss on one side)
C. Apraxia - inability to plan motor movements

18
Q

What are examples of sensory loss due to CVA?

A

Sensory cortex or sensory pathways are affected

A. Hypesthesia - decrease in sensation
B. Hemianesthesia - loss of sensation on one side
C. Paresthesia - abnormal sensations such as pins and needles, prickling, or tingling

19
Q

What are examples of speech/language/swallowing deficits as a result of CVA?

Which hemisphere of the brain is the speech center located?

A

A. Aphasia - language formation (Broca’s area) or recognition (Wernicke’s area)
B. DysARThria - articulating sounds for word formation
C. DysPHONia - making sounds (whispering, CN X, XI)
D. DysPHAGia - swallowing (CN IX)

(Emphasis added to aid in retention)

The speech center is in the left hemisphere. Left hemisphere strokes are more likely to affect the speech center.

20
Q

What are some examples of decreased cerebration?

A

A. Memory loss (diffuse cerebral damage or to hippocampus - short term)
B. Emotion control loss (limbic system)
C. Confusion, illusion, hallucination
D. Lethary, stupor, coma, death

21
Q

What are some abnormalities in vital functions that can occur due to CVA?

A

A. Abnormal blood pressure, heart rate/rhythm, and respiration (due to brainstem and medulla damage)
B. Abnormal Bladder or bowel function control

22
Q

What are some abnormalities of the special senses that can occur due to CVA?

A

A. Blindness or visual field deficits (hemi-anopsia)
B. Reduced smell or taste
C. Reduced hearing or balance (vestibular)

23
Q

What symptoms are characteristic of Middle Cerebral Artery Occlusion syndrome?

A

A. Contralateral hemiparesis and hemianesthesia - mainly the face and arm (pre- and post- central gyrus)
B. Aphasia (if dominant hemisphere is affected - rarely if non-dominant)
C. Contralateral homonymous hemianopsia (damage to optic radiations)
D. Anosognosia (inability of self-recognition of defect) & hemineglect syndrome (if non-dominant parietal lobe affected - rarely if dominant hemisphere)

24
Q

What symptoms are characteristic of Anterior Cerebral Artery Occlusion syndrome?

A

A. Contralateral hemiparesis and hemianesthesia (mainly lower extremities and foot)
B. Frontal and parietal lobe (inability to identify objects, apathy, personality changes)

25
Q

What symptoms are characteristic of Posterior Cerebral Artery Occlusion syndrome?

A

A. Contralateral homonymous hemianopsia (visual field loss of the same half for both eyes)
B. Visual agnosia (left occipital lobe)
C. Impairment of memory (medial temporal lobe)

26
Q

What are the long range results of CVA?

A

A survivor of CVA will almost always make recovery (sometimes quite remarkably).

Improvement can occur in the first or second year and possibly even further with adequete care, training, and encouragement.

27
Q

What is the pathophysiology of an individual losing conciousness?

A

Loss of consciousness occurs when cerebral artery pressure falls below 50-60 mmHg (normal 90) which compromises cerebral blood flow.

When arterial oxygen content (PO2) falls below 40 mmHg, there is insufficient oxygen supply.

28
Q

What process causes excitoxic cell death following CVA?

A

The ischemic cascade is the process that results in excitoxic cell death.

29
Q

Ischemic cascade - what are the factors that determine the type (necrotic vs apoptotic) and extent of cell death?

A
  1. Rate of onset
  2. Duration of ischemia
  3. Severity of occlusion/disruption
  4. Collateral circulation
30
Q

Ischemic cascade - Describe the steps of this process

A
  1. Loss of blood -> no new oxygen or glucose to cell
  2. Cell depleted of ATP and disruption of membrane transport systems (specifically ability to reuptake glutamate into cell)
  3. Inability to reuptake glutamate -> Increased extracellular [glutamate]
  4. Increased extracellular [glutamate] -> hyperexcitement of compromised and neighboring cells
    4a. Increased influx of Ca
    • This causes a cascade of destructive enzymes to enter cell and damage cell integrity, eventually leading to cell death

As the extracellular concentration of glutamate continues to increase, more and more neighboring cells undergo excitotoxic cell death

31
Q

What is the term for the area of the injury/lesion in which the ischemic cascade process is most robust?

A

Focal ischemic injury

32
Q

What is the term for the area of the injury/lesion in which the ischemic cascade process is least robust?

A

Penumbra

33
Q

What is the Monroe-Kellie Doctrine?

A

An increase in a component inside the cranium must be accompanied by a decrease in another component or there will be an increase in Intracranial Pressure (ICP).

(Normally, ICP in an adult is 8-18 mmHg.)

34
Q

Cerebral ischemia or hypoxia increases capillary permeability. How does this affect cranial tissue and intracranial pressure?

A

Increased capillary permeability causes tissue edema and increased ICP.

Tissue edema -> a vicious cycle of brain swelling and further ischemia due to mechanical compression of the microcirculation -> possible cerebral infarction

35
Q

What occurs when intracranial pressure (ICP) equals mean arterial pressure?

A

Cerebral flow ceases and brain death occurs

36
Q

Glucose is the primary energy source of the brain. What percentage of the body’s glucose is used by the brain?

The brain does not store glycogen, so how does the brain get glucose?

What happens if this glucose source is interrupted?

A

The brain uses 80% of the body’s glucose.

The brain gets all of its glucose and oxygen from blood. Any interruption in blood supply or a reduction in oxygen blood levels leads to unconciousness.

37
Q

How does an increase in blood pH affect brain function?

A

A increase in blood pH (ex. 7.4 to 7.8) leads to brain convulsions due to increased excitability of brain neurons.

38
Q

How does a decrease in blood pH affect brain function?

A

A decrease in blood pH (ex. 7.4 to 7.0) leads to a coma due to reduced excitability of brain neurons

39
Q

What is the term for drugs that improve blood flow and dissolve clots?

What is an example of one of these drugs?

A

Clot busters

Tissue plasminogen activator (tPA) - very effective at dissolving clots, which limits damage and functional loss. It is recommended to give tPA in the first there hours following the onset of symptoms.

40
Q

What are examples of neuroprotective drugs?

A
  1. Drugs to block glutamate release - reduce ischemic damage
  2. Glutamate/GABA antagonists - reduce tissue damage
  3. Calcium channel blockers
  4. Oxygen free radical scavenger drugs

532- Neuroscience - Exam 2 (6 decks)

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