Stroke & its consequencesPatient WW• Medical history:

– History of high blood pressure (hypertension)– Massive Stroke in Right Hemisphere

• Behavioral changes:– Partially paralyzed on left side.– Poor emotional control and judgment.– Unaware of his illness (anosognosia).

WW was Woodrow Wilson, 28th US President of USA

Special thanks to Chris Rorden, U. South Carolina

• Similar cases exist today– Sen Tim Johnson (D-South Dakota)– An hemorrhagic stroke (arteriovenous malformation)

StrokeStroke is a leading cause of disability. In western world:

1. Heart Disease2. Stroke (10% of deaths worldwide)3. Cancer

In USA alone- 500,000 people suffer stroke per year- 150,000 people die of stroke per year- 4 million living with stroke- $30 billion in health care costs

• 2/3 of strokes in people > 65 y-old

types of stroke

thrombotic emobolic

Ischemic (80%):the brain artery is clogged

(aka obstructive)

Haemorrhagic (20%):the brain artery ruptures: bleeding

- Some are transitory ischemic attacks (TIA).

- ‘Infarct’: Dead tissue following stroke

• Lesions look different depending on:– How old the lesion is: acute vs. 3 days old– Type of scan (CT, MRI)

• Example of Stroke:

T2 MRI

CT

acute +3days

newer MRI protocols• Diffusion-weighted imaging

– Strokes show up immediately.– Shows permanent white-matter damage.

•

Imaging Infarcts

• MRA (Magnetic Resonance Angiography):

MRI MRA stroke MRA Xray

Obstructive strokes: treatment

• Treatment:– Counterindicated for haemorrhagic strokes

• Prevention of all strokes– Control blood pressure– No smoking– Reduce cholesterol

– stent

Neuronal death in stroke

1. Obstruction 2. Reduction of O2 & glucose 3. Na/K pump stops working:4. Increase in action potentials5. Release of glutamate

1. Open Na channels -> Na rushes in -> so does water -> swelling 2. open Ca channels -> activate enzymes -> lesion cell

Stroke: Consequences

• As always, it depends on which brain area is affected

Example: – Haemorraghic Stroke: It usually lesions orbitofrontal cortex

Haemorrhagic strokes• aneurysm ruptures bleeding

• Symptoms:– Really bad headache .– Throwing up– Other neurological symptoms

• Treatment: Surgery to clip aneurysm

• Consequences: Orbitofrontal lesion (OFC)

• Symptoms: – Changes in personality

– This is true also of lesion of OFC lesion by other mechanisms (trauma, dementia)

aneurism: a sac-like protrusion of an artery caused by a weakened vessel wall

• symptoms

– Social disinhibition– Poor emotion regulation – Denial of deficit– Inability to navigate the social world

• Anatomy– Orbitofrontal Cortex– Amygdala

orbitofrontal lesion

Visual Areas for recognizing objectsLesion

Activation in fMRI in healthy adults

stimulus

Cerebral Achromatopsia: bilateral damage to V4

Visual brain area for Color perception

Area important for speech

• Left frontal cortex• Non-productive aphasia (broca’s aphasia)

• Also brought about by dementia that affects same area

• http://psych.rice.edu/mmtbn/

Hippocampus

• Memory deficit

• But so does Alzheimer’s disease

In sum

• Two types of stroke– Ischemic– Haemorraghic

Behavioral consequences are determined by location of lesion!

Spared slides

•

Ischemic Strokes

Major Arteries Carotid Anterior Cerebral Middle CerebralPosterior Cerebral

Occlusion of middle cerebral artery (MCA)

• embolism travels up carotid artery

• MCA supplies lateral bank of cortex (image from strokecenter.org)

• Damages regions near superior temporal sulcus (sylvian fissure) (figure shows regions damaged in 24 MCA patients, Mort et al. 2003)