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MD4001 > Cerebral Circulation + Stroke > Flashcards

Cerebral Circulation + Stroke Flashcards

1
Q

Draw the circle of Willis.

A

Refer to slide 2 in lecture.

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2
Q

Identify the main components of the circle of Willis.

A

There are three main (paired) constituents of the Circle of Willis:
• Anterior cerebral arteries – terminal branches of the internal carotid arteries.
• Internal carotid arteries– located immediately proximal to the origin of the middle cerebral arteries
• Posterior cerebral arteries – terminal branches of the vertebral arteries.

To complete the circle, two ‘connecting vessels’ are also present:
• Anterior communicating artery – connects the two anterior cerebral arteries.
• Posterior communicating artery – branch of the internal carotid, this artery connects the ICA to the posterior cerebral artery.

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3
Q

What are the main components of the anterior cerebral circulation ?

A

-Internal carotids, supply:
Anterior 3/5 of cerebrum
Diencephalon

-Main branches:
Middle cerebral artery
Anterior cerebral artery
Striate arteries (perforating small blood vessels, supplying area of internal capsule and basal ganglia)

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4
Q

What are the main components of the posterior cerebral circulation ?

A

-Vertebrobasilar arteries (Vertebral arteries, forming basilar artery)
-Supply:
Posterior 2/5 of cerebrum
Diencephalon
Cerebellum
Brainstem

-Major branches: 
Posterior cerebral arteries
Striate and thalamus
Pontine
Cerebellar
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5
Q

Are strokes more common in anterior, or posterior circulation ?

A

Strokes and more common anteriorly

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6
Q

What is a possible cause of lateral medullary syndrome ?

A

Blockage in posterior inferior cerebellar artery

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7
Q

What is a possible cause of third nerve compression ? What is the consequence of this ?

A

Aneurysm in posterior communicating artery (very close to third nerve), causing eye to go out and down, often with dilated pupil

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8
Q

Identify possible consequences of lesions affecting the cavernous sinus.

A

E.g. infection from around the eye, tracking back along veins, into the cavernous sinus –> Cavernous sinus thrombosis, possible rupture of carotid artery

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9
Q

Identify the contents of the cavernous sinus.

A
  • Cranial nerves 3, 4, 5, 6 are around cavernous sinus

- Internal carotid arteries

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10
Q

What is the main characteristic of strokes, with regards to timeline ?

A

SUDDEN ONSET

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11
Q

Define stroke, and distinguish it from a TIA.

A

Interruption of the blood supply to a focal partof the brain causing loss of neurological function.
Symptoms last more than 24 hours, or lead to death with no apparent cause other than that of vascular origin

IN CONTRAST
TIA has the same causes but symptoms last less than 24 hours

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12
Q

Identify the main types of strokes.

A

Ischemia (80%)
Hemorrhagic (15%)
Subarachnoid hemorrhage (5%)

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13
Q

What are the causes of hemorrhagic strokes ?

A

-Hypertension (perforating arteries, especially branches of the middle cerebral artery e.g. choroidal and striate arteries are affected)
-Tumour bleeding disorder
-Vascular malformation (especially arteriovenous malformation)
-Amyloid angiopathy (excess amyloid build up in blood vessels)
(Cerebral Venous Sinus Thrombosis can present with cerebral hemorrhage)

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14
Q

Where do hemorrhagic strokes tend to occur ? What other pathological consequences tend to occur as a result of these ?

A

Primary brain damage
-Basal ganglia and internal capsule (because of hemorrhage from perforating blood vessels)

Secondary brain damage
-Surrounding oedema, vascular disease

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15
Q

What are the causes of ischemic strokes ?

A
  • Cardioembolism
  • Large vessel atherothrombosis (e.g. aorta, internal carotid)
  • Small vessel disease (hypertensive-related occlusion of vessels in the brain)
  • Carotid/vertebral dissection (causing blood going into lining of blood vessels)
  • Hypoperfusion (especially if inadequate collateral circulation, especially in watershed areas)
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16
Q

Describe the histology of ischaemic strokes.

A

Core- all cells are dead
Penumbra- some cells might survive

Size of infarct, area of core, amount of collateral circulation will all influence the eventual outcome from strokes

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17
Q

How many neurons are lost per year in normal aging ?

A

~30 milion neuron loss per year in normal aging

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18
Q

Define watershed area.

A

Areas that are slightly less perfused. If there is a drop in BP very quickly, can cause strokes by having lack of perfusion in those watershed areas (e.g. in arrythmias, MIs). There are three:

1) Cortical Border Zone (between ACA and MCA)
2) Internal Border Zone (between LCA and MCA)
3) Cortical Border Zone (between MCA and PCA)

Especially occur if collagen abnormality present

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19
Q

How is brain blood flow controlled ?

A

Autoregulation (cerebral blood vessels dilate or contract to control amount of blood that gets to brain)

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20
Q

What are consequences of impaired dilation, and force-mediated dilation in the brain ?

A

IMPAIRED DILATION

  • Artery collapse
  • Ischemia

FORCE-MEDIATED DILATION

  • Increased flow
  • Vasogenic edema
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21
Q

Which part of the brain is affected by posterior strokes ?

A

Temporal lobe

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22
Q

Which part of the body is affected by an anterior stroke.

A

Often leg (particularly medially), affected by ACA stroke

23
Q

Are most strokes anterior or posterior ? Which artery is most often affected ?

A

Most strokes are anterior

Middle cerebral artery most often affected, posterior cerebral artery less so, anterior cerebral artery even less so.

24
Q

What proportion of all strokes do small vessel strokes account for ?

A

10-15%

25
Q

Identify the main steps taken by first responders in a suspected stroke patient.

A
  • FACE (facial asymmetry)
  • ARMS (weakness, esp. asymmetrical weakness)
  • SPEECH (speech disturbance)
  • TIME (time to call 999 if you see any single one of these signs)

Check glucose! (if possible, because hypoglycemia can mimic stroke)

26
Q

Identify the main questions about a stroke which will guide treatment.

A
  • Is it a stroke?
  • What type?
  • Which part of the brain is affected?
  • What caused the stroke?
  • What is the prognosis?
  • What are the risk factors?
  • What are the functional+emotional consequences?
27
Q

Identify the most common presenting symptoms and signs of a stroke.

A
  • Motor
  • Sensory
  • Speech
  • Hemianopia (less vision or blindness (anopsia) in half the visual field, usually on one side of the vertical midline)
  • Ataxia
  • Diplopia
28
Q

Describe emergency room assessment of a suspected stroke.

A

Airway
Breathing
Circulation

Clarify the history!
Clarify the history! !
Check medical background Check the signs

? Stroke mimics excluded
Level 1 investigations

29
Q

Describe examination in vascular neurology.

A

-BP and pulse measurments in 2 arms
-Conscious level (GCS)
-Cardiac and carotid bruits
-BM/blood glucose value
-Neck stiffness/meningism (Kernig’s/Brudzinkski signs)
-Abnormal or involuntary movements
-Any seizures-like activity
-Skin rash/infarcts e.g. vasculitisc, papular rash
-Specific neurological :
Eye movements (gaze preference, fixed deviation)
Speech, visual fields, inattention, motor and sensory
Gait assessment

30
Q

Identify the main ways to classify strokes.

A

• Oxford Community Stroke Project (OCSP)
-clinical

• TOAST classification
-mechanism (e.g. large vessel, small vessel, cardioembolic)

•Carotid or vertebrobasilar territory

31
Q

Describe the OCSP classification of strokes.

A

Dependent on which of these are affected:

  • Motor/sensory pathways
  • Visual pathways
  • Higher cortical functions
  • Brainstem functions

1) Total Anterior Circulation Syndrome
-triad of hemiparesis (or hemisensory loss), dysphasia (or other higher cortical function) and homonymous
hemianopia

2) Partial Anterior Circulation Syndrome
- brainstem, cerebellar and/or isolated homonymous hemianopia

3) Lacunary Syndrome
- pure motor, pure sensory, sensorimotor, ataxic hemiparesis

4) Posterior Circulation Syndrome
- 2 of the features of TACS or isolated dysphasia or parietal lobe signs (e.g. inattention, agnosia, apraxia, agraphaesthesia, alexia)

32
Q

Identify a tool to assess TIAs and risk of stroke, and some of its criteria.

A

ABCD2 Assessment in TIA and risk of stroke

  • Age
  • BP
  • Clinical features (e.g. unilateral weakness, speech disturbance without weakness)
  • Duration of symptoms in minutes
  • Diabetes
33
Q

Identify the main stroke mimics.

A
  • Seizures
  • Sepsis
  • Syncope
  • Space-occupying lesion (tumor, subdural)
  • Somatisation (hysteria)
34
Q

Identify red flags in the context of strokes.

A
  • No history
  • No risk factors
  • No imaging abnormality
  • Young age
  • Seizures
  • Unusual headache
35
Q

Identify common risk factors for stroke in the elderly.

A
  • Hypertension
  • Ischemic heart disease
  • Smoker
  • Peripheral vascular disease
  • Transient Ischemic Heart Attack
  • Diabetes Meillitus
36
Q

Identify aetiologies of ischemic stroke in the youth.

A
  • Artery dissection

- Cardiac embolism

37
Q

Identify investigations for strokes.

A
  • Good history and examination
  • ECG/Holter (24h ECG), ECHO
  • Cholesterol/autoimmune (causing inflammation of blood vessels) and thrombophilia (causes of clotting) screen
  • Carotid doppler (if anterior circulation stroke)
  • CT brain/MRI brain
  • Cerebral angiography
38
Q

Identify indications for urgent head imaging.

A
  • Depressed level of consciousness
  • Unexplained progressive or fluctuating symptoms
  • Papiloedema, neck stiffness or fever
  • Severe headache at onset
  • History of trauma prior to onset
  • Indication for thrombolysis or anticoagulation
  • History of anticoagulant treatment or known bleeding tendency
39
Q

How does CT help stroke diagnosis ?

A

-Helps to exclude a bleed
-May also show:
Cerebellar hemorrhage
Early ischemia
Tumors
SDH
Mass effects (if big stroke, mass effect occurs, cannot see sulci due to swelling of brain)
Loss of normal grey white differentiation (especially a bit later on)

40
Q

How does MRI help stroke diagnosis ?

A

DWI = Diffusion weighted images (basically mix of T2 and
diffusion weighting).
ADC: Apparent Diffusion Coefficient, it’s pure diffusion of water.

Acutely, in stroke, 35 minutes after symptom onset, have high signal DWI and low signal ADC.
Over period of time, the two signals reverse:
-1-2 weeks, DWI stays high, ADC signal increases to normal.
-2 weeks +, DWI becomes lower, ADC becomes high and stays high).

This can help us to understand the timeframe of a stroke.

41
Q

Distinguish pros and cons between CT, and MRI.

A 
CT
Pros: 
-Can detect bleed
-Available 24/7
-Quick
Cons: 
-Lacks sensitivity
MRI
Pros: 
-Sensitive
-Diagnostic
-Management
-Pronostic
Cons: 
-Limited availability
-Precautions
-Slow
42
Q

Describe management of acute strokes.

A
  • Aspirin (300 mg/d) in ischemic stroke (don’t need to have scan first)
  • Thrombolytic treatment with IV r-tPA if onset < 4.5 stroke, hemorrhage excluded by imaging, and considered suitable for treatment
  • Endovascular treatment/mechanical thrombectomy (with clot-retrieval decide in selected patients)
  • Aggressive early BP Rx in ICH; SBP < 140
  • Neurosurgery opinion for secondary hydrocephalus especially in cerebellar stroke
  • Anticoagulation in AF (once bleed excluded and usually after 10-14 days of stroke)
  • In ischemic stroke, avoid antihypertensive medications unless MABP > 130 mmHg. In hemorrhagic stroke, aim for SBP <140 mmHg especially in the first 6 hours
  • If BP persistently elevated, treat with IV Labetolol (avoid abrupt falls in BP)
  • In raised ICP, hyperventilate mechanically + mannitol + decompressive hemicraniectomy
43
Q

Describe diagnosis of SAH.

A

-CT brain/lumbar puncture if CT normal looking for bilirubin and xanthochromia + Cerebral angiogram

44
Q

Describe management of SAH

A
  • Airway: intubate if severe hypoxaemia
  • Fluid: 3L of 0.9% NaCl per 24 hrs
  • BP: Keep MABP < 130 mmHg. If higher, use IV Labetolol, or esmolol or enalparil
  • Nimodipine
  • Codeine or tramadol for pain (avoid NSAIDs)
  • Phenytoin if seizures have occurred
45
Q

Describe secondary prevention of strokes (e.g. if someone has had stroke in the past).

A
  • Anti-thrombolytics: Clopidogrel or Aspirin + Dipyridamole. In AF: Warfarin or NOAC (rivaroxaban)
  • BP: Target BP < 130/80 with Calcium channel blocker, thiazide diuretic (bendroflumethazide), ACE inhibitor (e.g. ramipril)
  • Anti-lipids: if total cholesterol is high, treat with statin
  • Carotid endarterectomy (CEA) should be considered for all symptomatic stroke/TIA patients and with 50-99% stenosis
46
Q

When should carotid endarterectomy be performed fas a secondary prevention measure for stroke ?

A

CEA should be performed as soon as patient is stable and fit for surgery: ideally within 1 week

47
Q

Describe long term management of strokes.

A
  • Psychosocial and support needs reviewed on regular basis. Potential issues include: communication, mobility, driving, depression, pressure sores, sepsis, nutrition, post-stroke seizures, shoulder pain, cognitive impairment, and behavioural problem
  • Multidisciplinary team approach, including: physio, occupational therapy, social worker, speech and language therapy, clinical psychologist, dietician, stroke nursing and GP
48
Q

What is the rank of strokes as a cause of death worldwide ? What proportion of that is in the first month ?

A

Mortality: 2nd commonest cause of death wordwide

49
Q

What is the proportion of mortality of ischemic, and hemorrhagic strokes ?

A

Ischemic: 40%
Hemorrhagic: 70%

50
Q

What proportion of all survivors are disabled ?

A

1/3 near independant
1/3 severely disabled
1/3 independent with support

51
Q

What is the commonest cause of adult disability ?

A

Strokes

52
Q

How large is the risk of developing a stroke after a TIA ? When is this risk the highest ?

A

20% within first month with highest risk within first 72 hours

53
Q

What is the commonest cause of adult disability ?

A

Strokes

MD4001 (74 decks)

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