Ischemic Stroke: Basic Anatomy and Pathophysiology

Dr. Ajay Kumar AgarwallaPhase- A Resident (Neurology)Blue Unit, Neurology dept. , BSMMU

Road Map

• Artery supply of the brain

• Findings associated with occlusion

• Key features of cerebral blood flow

• Auto regulation of cerebral blood flow

• Pathophysiology of infarction in brain

• Factors influence ischemic stroke

Arterial supply of the Brain

Anterior Cerebral Artery OcclusionContralateral hemiparesis and hemisensory loss involving

mainly the leg and foot (paracentral lobule of cortex)Inability to identify objects correctly, apathy, and personality

changes (frontal and parietal lobes)

Contralateral hemiparesis and hemisensory loss involving mainly the face and arm (precentral and postcentral gyri)

Aphasia if the left hemisphere is affected (rarely if the right hemisphere is affected)

Contralateral homonymous hemianopia (damage to the optic radiation)

Middle Cerebral Artery Occlusion

Contralateral homonymous hemianopia with some degree of macular sparing (damage to the calcarine cortex)

Visual agnosia (ischemia of the left occipital lobe)

Impairment of memory (damage of medial aspect of the temporal lobe)

Posterior Cerebral Artery Occlusion

Key features of blood flow in BRAIN

•  In an adult, CBF is typically

750 ml/min or

45-50ml/100g/min or

15 % of the cardiac output (CO)

In normal individuals, CBF remains constant when

the mean arterial pressure varies between

“60 and 160 mmHg”

Ideal Cerebral Auto Ideal Cerebral Auto regulationregulation

Lassen NA. Physiol Rev. 1959;39:183-238Strandgaard S, Paulson OB. Stroke.1984;15:413-416

Matter of Concern

Cerebral Blood Flow (CBF) :

• Less than 23ml/100g/min, physiological

electrical function of the cell begins to fail-

“ischemic penumbra”.

• Below 10 ml/100g/min, ionic membrane

transport failure, Irreversible cell death-

which leads to- “infarction”.

Factors Influence Ischemic Stroke

• Rate and onset of duration• Collateral circulation• Systemic circulation• Hypercoagulable states• Increased temperature• Hyper/hypo glycemia

Reference

Snells Clinical Neuroanatomy, 7th edition

Davidson’s Principles and Practice of Medicine,

22nd edition

Harrison’s Principles of Internal Medicine, 19th

edition

http://what-when-how.com/neuroscience/blood-

supply-of-the-central-nervous-system-gross-ana

tomy-of-the-brain-part-2/

http://en.wikipedia.org/wiki/Cerebral_blood_flow

Stroke Pathophysiology Sid Shah, MD