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Nueroscience 206 > Neurodegeneration One - Vascular Stroke > Flashcards

Neurodegeneration One - Vascular Stroke Flashcards

1
Q

Define stroke

A

Damage to the brain or spinal cord caused by abnormality of its blood supply

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2
Q

How is stroke recognized?

A

1) Sudden onset of focal neurological symptoms over a few seconds or minutes that persist for more than 24hrs
2) Symptoms and signs of a focal brain lesion (subarrachnoid hemorrhage is an exception)

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3
Q

Whats the stroke incidence in nz?

A

8000 per year

mean age for stroke is 73 years
25% occur in under 65
Third most common cause of death

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4
Q

What are the type of stroke?

A

1) Ischemic stroke (infarction)
2) Intracerebral hemorrhage (ICH)
3) Subarrchnoid hemmorhage (SAH)

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5
Q

What are the characteristics of an ischemic stroke?

A
  • causes 80-85% all strokes
  • Caused by loss of blood flow to part of brain or spinal cord which deprives the area of oxygen, glucose and leads to infarction (necrosis)
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6
Q

What are the characteristics of an ICH?

A
  • causes ~15% all strokes
  • Bleeding into the brain parenchyma
  • Usually from a small artery supplying the deep WMT or basal ganglia
  • Results in a heamatoma causing symptoms by cutting off pathways in the brain and by exerting pressure on the surrounding brain tissue
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7
Q

What are the characteristics of SAH?

A
  • Least common (<5%)
  • Mostly younger people
  • Bleeding into the subarrachnoid space around the brain and spinal cord
  • Typically caused by blood leaking out of blood vessel, usually an aneurysm (Berry)
  • Different symptoms to other strokes.
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8
Q

What are the different symptoms of SAH?

A
  • Patients have sudden onset of extremely severe headache (thunderclap) +/- abrupt loss of consciousness
  • Headache usually severe in the back of the head
  • Associated with neck stiffness due to irritation of the meninges
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9
Q

How can the symptoms of a ischaemic stroke differ?

A

The symptoms depend on which blood vessels are occluded and the part of the brain that those arteries supply

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10
Q

What are the three possible areas of circulation that could be occluded in an ischaemic stroke?

A
  1. Anterior circulation (FC,T,P)
  2. Posterior circulation (Brainstem, T, SC)
  3. Lunar infarcts (penetrating arteries into deep WM)
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11
Q

What are the three main causes of ischaemic stroke?

A
  1. Arterial disease
  2. Embolism
  3. Reduced systemic perfusion pressure
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12
Q

What is the most common type of arterial disease that causes ischaemic stroke?

A

Atherosclerosis

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13
Q

What does atherosclerosis mainly effect?

A

Bifurcation of arteries

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14
Q

what are four ways atherosclerosis can causes ischaemic stroke?

A
  1. Ulceration of endothelium -> plaque forms -> parts break off travels downstream and blocks smaller art. (thromboembolism)
  2. Adhesion of platelets to wall can trigger coagulation cascade = occlusive thrombosis, can propogate and block art.
  3. Low flow and perfusion pressure from occluded art. = infarction of that part of brain
  4. Haemorrhage into a plaque occludes lumen.
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15
Q

How does an embolism cause ischemic stroke?

A

Thrombus or other material in the heart may break loose and block brain art.

thrombus may be caused by atrial fibrillation, heart valve disease, infection of heart valve, infarction of heart

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16
Q

what are the causes of reduced systemic perfusion pressure?

A

Pump failure
Shock - dehydration, blood loss

Therefore perfusion pressure in some areas of the brain are reduced and die.

17
Q

What is the pathophysiological cause of stroke?

A
  • Brain doest store ATP
  • Needs constant ATP
  • Produces ATP from GLUCOSE only
  • Brain recieves 20% blood flow for this purpose (50ml per 100g brain)

-Damage occurs at <5ml/100g though EEG activity falls at 20ml/100g

18
Q

In the brain what does loss of ATP production cause?

A

No ATP =

  • No ion gradient
  • redistribution of ions (esp Ca in) compromises metabolic function
  • Oxygen free radicals form and destroy organells
  • Loss of cell polarity means lots of excitatory neurotransmitter release

== Irreversible damage (necrosis) even if reperfusion

  • If ischaemic but not enough to cause necrosis, apoptosis can occur
19
Q

What is the degree of ischemia determine by?

A

How low the perfusion is

20
Q

Surrounding the central ischemic infarct zone is?

A

Zones of low perfusion with EEG + Metabolic failure = known as the ischaemic penumbra

21
Q

What is the fate of the ischaemic penumbra?

A

The fate of the ischemic penumbra is determined by the duration, intensity of ischemia

  • If reperfused early enough it can be salvaged
  • If biochemical damage is too severe then necrosis occurs
22
Q

What are the clinical syndromes of ischaemic stroke?

A
  1. Total Anterior Circulation Infract (TACI)
  2. Partial Anterior Circulation Infarct (PACI)
  3. Posterior circulation infarct (POCI)
  4. Lunar Infarct (LACI)
23
Q

What cause TACI?

A

Occlusion of internal carotid artery or middle cerebral artery

24
Q

What are the symptoms of TACI?

A
  • Focal higher cerebral dysfunction (PIMB)
  • Homonymous visual field defect (optic art is branch of carotid)
  • Unilateral motor and/or sensory deficit in at least two of the following : face, arm, legs
25
Q

What causes PACI?

A

Occlusion of the internal carotid or middle cerebral art, or one of its branches, or anterior cerebral art.

26
Q

What are the clinical features of PACI?

A

Two or three components of TACI syndrome

or

Focal higher cerebral dysfunction alone

or

unilateral motor/ sensory deficit which is more restricted than a lacunar infarct (i.e isolated hand involvement)

27
Q

What are the causes of POCI?

A

Occlusion of vetebral, basilar, or posterior cerebral art.

28
Q

What are the clinical features of POCI?

A

Can include any of the following:

  • Ipsilateral crainial nerve pasly + Contralateral motor and or sensory deficit
  • bilateral motor and/or sensory deficit
  • Disorder of conjugate eye movements
  • Isolated homonymous hemianopia
29
Q

What is the cause of LACI?

A

Small deep infarct caused by occlusion of a penetrating artery

Can be occluded by atheroma, lipohyaline degeneration

30
Q

What are clinical features of LACI?

A

Pure motor stroke
Pure hemisensory stroke
ataxia

BUT NOT

  • visual problems
  • brains stem abnormality
  • Impaired consciousness

any grey matter related stuff

31
Q

What is the treatment of acute ischeamic stroke?

A

Treatment must occur within hours of symptoms before irreversible damage has occurred

  • Prevention of clot formation, propagation and embolism
  • Removing the vascular obstruction (thrombolysis)
  • Clot retrieval
32
Q

What may present in a similar manner to a stroke?

A

Transient ischaemic attack (TIA)

33
Q

What is a TIA?

A

Sudden onset of focal neurological conditions that last less than 24 hrs

34
Q

What does TIA represent?

A

Temporary impairment of brain function

– identifier for stroke potential

35
Q

How do you prevent stroke and TIA?

A

Modifying risk factors for stroke (health outcomes)
Anti-platelet medication
Treatment with anticoagulants
Carotid Endarterectomy (for patients with severe stenosis)

36
Q

What are the causes of ICH?

A

Hypertension
Cerebral Amyloid Angiopathy
Malformation of vessels, tumors, drugs

37
Q

What are the causes of SAH?

A

berry aneurysms

Smoking plus other lifestyle factors

Nueroscience 206 (33 decks)

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