Cerebrovascular Accident

Aka: Stroke

Brain Attack

http://www.strokecenter.org/education/index.html

In this Session

• Brain structure and function• Cerebral circulation• Haemorrhagic stroke• TIA• Ischaemic stroke• Manifestations• Diagnosis and management• Long term disabilities

Review of Brain Structure & Function

Cerebral Cortex

– Divided into Hemispheres

– Functions• Motor - Controlling voluntary movements

• Sensory - Registers and processing sensations

• Association - Higher mental functions

• Language - Comprehension and Production

Cerebral Hemispheres: Lobes

– Frontal

– Temporal

– Parietal

– Occipital

Other Brain Structures

– Brainstem – Medulla – Reticular formation

Other Brain Structures

– Thalamus

Other Brain Structures

– Cerebellum

Other Brain Structures

– Hypothalamus

Language

• Wernicke’s Area– Temporal lobe

– Recognition of spoken & written language

– Composition of spoken and written language

Language

• Broca’s Area– Frontal lobe

– Speech motor function

Coordination of Language in the Brain - How do we read aloud?

Vision

Cerebral Circulation

Arteries supplying the Brain

• Aortic Arch Common Carotid Artery (left & right) internal carotid artery (Left & Right) Circle of Willis

• Aortic Arch Subclavian Arteries Vertebral Arteries (Left & Right) Merge to form Basilar Artery Circle of Willis

• Circle of Willis left & right: Anterior, Middle & Posterior Cerebral Arteries

Definition of Stroke

• Acute focal neurological deficit as a result of vascular disorder

Epidemiology

• Third leading cause of death

• Over 70% strokes in people aged > 65 yr

• Ave. age males 68 yr, female 74 yr

• 1998 Age-standardised stroke mortality (per 100,000 pop) is 43 male, 42 female

• A leading cause of Disability

Risk Factors for Stroke

• Advanced age• Systolic hypertension• Diabetes mellitus• Hypercholesterolemia• Carotid artery stenosis• TIAs• CIGARETTE SMOKING• Lack of exercise• CV disease especially atrial fibrillation• Increased weight

Non-Modifiable Risk Factors

• Age– Risk doubles for each decade after 55 years of

age

• Gender– Men slightly higher than women

• Race

• Heredity

AGE and STROKE

Modifiable Risk Factors

Hypertension RR 4.0

Diabetes RR 1.8

Smoking RR 1.7

Coronary disease RR 2.2

TIA RR 3.9

Atrial fibrillation RR 2.6-4.5

Hyperlipidemia RR 1.8-2.6

Modifiable Risk Factors

For ischaemic stroke:

• Being overweight increases risk by 22%

• Being obese increases risk by 64%

Diet and Stroke• Fish: 3 servings a day associated with a 6% lower

risk of stroke• Fruits and vegetables: >5 servings a day

associated with a 26% lower risk of stroke• Meat: Each daily serving associated with a 24%

increased risk of stroke• Reduced-fat milk: associated with a lower risk of

stroke vs full-fat milk• Chocolate: High consumption associated with a

29% lower risk of stroke

Diet and Stroke• Coffee: 3 to 4 cups per day associated with a 17%

lower risk of stroke• Tea: ≥3 cups per day associated with a 21% lower

risk of stroke• Sugar-sweetened beverages: high intake

associated with increased obesity, diabetes, metabolic syndrome, and coronary heart disease

• Whole grains: high intake associated with a 21% lower incidence of cardiovascular events

• Rice: intake not associated with risk of stroke

Types of Stroke

• Haemorrhagic

• AND

• Ischaemic

Haemorrhagic Stroke

• 15% of strokes

• Release of blood into the extravascular space

• Caused by:– Hypertension– Aneurysms – Head Injury

Berry Aneurysm

• Cause unknown

• Usually around Circle of Willis

Haemorrhagic Stroke

• Rupture of blood vessel causes:– Haemorrhage– Oedema– Compression

• Death is common

Haemorrhage

• Intracerebral haemorrhage

• Subarachnoid haemorrhage

Transient Ischaemic Attack (TIA)

• Ministroke or Brain angina

• Fleeting attack of paralysis, numbness, tingling, aphasia, unilateral blindness or dizziness

• Zone of penumbra without central infarction

• Last less than 24 hours

TIA’s

• Warning

• First month after a TIA, carries a 4-8% risk of stroke

• First year, 12-13%; 24-29% over 5 years

• Note: Do not have associated pain (rare), so people may ignore them

• Person should seek immediate medical attention

Ischaemic Penumbra

• Prolonged hypoperfusion (<10 ml/100 gm/min) leads to Cell death

• Ischaemic penumbra is a zone of dysfunctional but not dead brain tissue surrounding an infarct

• Dysfunctional tissue may infarct • “Brain is Time”- need treatment within 3

hours

Ischaemic Stroke

• 85% of all strokes

• Ischaemic: lack of blood flow

• Caused by– Emboli– Thrombosis

• Types are Thrombotic Stroke, Cardiogenic Embolic Stroke, Lacunar Stroke

Thrombotic Stroke

• Most common

• Common sites are the origins of internal carotid, vertebral arteries and junctions of basilar and vertebral arteries

• Normally a single cerebral artery is affected

Cardiogenic Emboli Stroke

• Caused by a moving blood clot

• Most common site is middle cerebral artery

• Most emboli originate in the left heart

• Atrial fibrillation and other heart disease predisposes to embolus formation

Lacunar Stroke

• Small infarcts in deeper, noncortical parts of brain or brain stem

• Cause can be embolism, hypertension, small haemorrhages

• Leave lacunae upon healing

• Produce “lacunar syndromes”

• MRI for diagnosis

Manifestations

Terminology

• Hemiplegia – Paralysis on one side of body• Hemiparesis – weakness on one side of

body• Hemianopia –vision loss in one side of

visual field• Aphasia –language disturbance (speech,

comprehension, writing)• Dysarthria – slurred speech

Terminology

• Diplopia – double vision

• Dysphagia – difficulty swallowing

• Agnosia – impairment of recognition of sensory stimuli

• Ataxia – imbalance

• Apraxia – inability to properly execute movements

Presentations of Acute Stroke

• Alteration in Consciousness• Stupor, delirium, coma, confusion,

memory loss, seizures• Headache; severe and/or neck or facial

pain (Not common)• Aphasia• Facial weakness or asymmetry

Presentations of Acute Stroke

• Weakness, paralysis, or sensory loss

• Ataxia (poor balance, clumsiness, or difficulty walking)

• Visual loss, monocular or binocular

• Intensive vertigo, double vision

Anterior Cerebral Artery Occlusion

• Paralysis of contralateral leg

• Paresis of contralateral arm

• Problems making decisions

• Speech disturbance (aphasia if left hemisphere stroke)

• Some sensory loss over toes, foot, leg

Middle Cerebral Artery Occlusion

• Contralateral hemiplegia (face & arm)

• Contralateral Sensory impairment

• Speech disturbance (aphasia), including difficulty in comprehending written words and writing

• Some visual field loss

Posterior Cerebral ArteryOcclusion

• Visual distubances (Hemianopsia, colour blindness)

• Memory deficits

• Loss of all sensory modalities (thalamus)

Basilar Artery Occlusion

• Complete obstruction of the basilar artery is usually rapidly fatal

• Rapid onset of unconsciousness and deepening coma.

• Supplies the Brain Stem

Vertebral Artery Occlusion

• Vertigo at onset

• Visual distubances (diplopia)

• Ataxia

• Dysphagia

• Dysphonia

Stroke Diagnosis

• Neurological Assessment

• Neuroimaging– Eg. CT, MRI (important for differentiating

ischaemic from haemorrhagic stroke)

• Vascular Imaging– Eg. Angiography

• Carotid Ultrasound

Management: Ischaemic Stroke

• Goal: protection of penumbra zone– Maximize cerebral blood flow and blood volume,

reduce viscosity– Maintain perfusion pressure

• Recanalization with thrombolytic therapy Eg. Tissue plasminogen activator (tPA), streptokinase, urokinase

• Anticoagulants to block occlusive processes (eg. Aspirin)

Long Term Disabilities

• Motor deficits

• Language and speech problems

• Dysarthria

• Aphasia

• Denial or hemiattention