Stroke & its consequences Patient 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, 28 th 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)

Stroke Stroke is a leading cause of disability. In western world: 1.Heart Disease 2.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): MRIMRAstroke 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 potentials 5.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 objects Lesion 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

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 Cerebral Posterior 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)