Chapters 27 28 Tripple

Cerebral Circulation „

Brain needs a lot of nutrients … Oxygen … Glucose

„

Interrupt … 5s …5

= unconscious minutes = brain damage

Supply Internal Carotid Arteries „ Vertebral Arteries „ Basilar Arteries „

Internal Carotid „

Common-> … Internal … External

„

4 segments … Cervical … Intrapetrosal „

Temporal bone

… Intracavernous „

Cavernous sinus

… Cerebral

1

Internal Carotid „

Feeds branches: … Ophthalmic

Optic nerve & retina „ Anastomotic connections with external carotid „

…

Bypass for internal carotid occlusion

Internal Carotid „

Feeds branches: … Anterior

choroidal

Optic tract, cerebral peduncles, LGN, posterior limbic system „ Small diameter „

…

Prone to occlusion by thrombus

Internal Carotid „

Feeds branches: … Anterior „

„

„

cerebral

Left and right connected by anterior communicating artery Medial surface of cerebral hemisphere Occlusion …

Contralateral lower extremity ƒ Weakness ƒ Paralysis ƒ Sensory deficit

2

Anterior Cerebral „

Medial striate

„

Orbitofrontal

… Striatum

… Orbital

gyri … Septal area … Displaced by tumors „

Angiogram

Anterior Cerebral „

Frontopolar

„

Callosomarginal

… Frontal

lobe

… Parietal

„

lobe

Pericallosal … Parietal

lobe

Internal Carotid „

Feeds branches: … Middle „

„ „

„

cerebral

Primary and association motor & somatosensory Prefrontal cortex Broca’s and Wernicke’s Occlusion … … … …

Contralteral paralysis Contralateral somatosensory loss Aphasia Changes in personality and thinking

3

Middle Cerebral Artery „

Cortical … Frontal „

Rolandic …

S1 & M1

… Temporal „

Angular

… Parietal

„

Central … Basal

ganglia

Internal Carotid „

Feeds branches: … Posterior

communicating „

Interior carotid to posterior cerebral

Vertebral Artery „ „ „ „

Off of subclavian Enters through foramen magnum Internal surface of medulla 2 vertebrals join at pons to form basilar artery

„

Posterior spinal …

„

Posterior medulla, posterior column and dorsal horn

Anterior spinal … …

Ventral medulla, anterior 2/3 of spinal cord Occlusion „

„

Paralysis below spinal location

Posterior inferior cerebellar artery …

…

Olive, inferior cerebellum, part of medulla, choroid plexus of 4th ventricle, deep cerebellar nuclei Occlusion „

Lateral medullary syndrome

4

Basilar Artery „

Paramedian penetrating … Brainstem

„

Short circumferential … Lateral

„

pons

Long circumferential … Auditory „

„

artery

Inner ear and root of facial nerve Occlusion: deafness

„

Long circumferential … Anterior

inferior cerebellar „

Inferior cerebellum, tegmentum

… Superior

cerebellar

artery „

Superior cerebellum, tegmentum, inferior colliculus

Basilar Artery „

Posterior cerebral …

…

Medial occipital lobe, temporal lobe, caudal parietal lobe, corpus callosum Occlusion „

Homonymous hemianopia …

„

Bilateral … …

…

Spares macular vision ƒ Occipital pole ƒ Middle cerebral artery Prosopagnosia Achromatopsia

Increased intracranial pressure „ „

Compresses Cortical blindness

Circle of Willis „

„

„ „

Anterior, middle and posterior cerebral arteries Anterior and posterior communicating arteries Collateral circulation Really only a circle in 20% of people

5

Cerebral vasculature „

Arteries … Thinner

walls of external elastics … Astrocyte processes are part of walls … Lack „

BBB

… Surrounded

„

Capillaries

„

Veins

… Surrounded

by arachnoid/pia membranes by astrocyte processes

… Thinner

walls valves/muscles

… No „

Allow flow in either direction …

Reversal of flow in occlusion

Cerebral Venous Drainage „

Superficial drainage … Superior „

… Middle „

cerebral

Cavernous sinus

… Inferior „

cerebral

Superior sagittal sinus

cerebral

Cavernous and transverse sinuses

Cerebral Venous Drainage „

Internal Cerebral … Thalamostriate … Septal

vein

vein

„

Basal Vein of Rosenthal

„

Great Cerebral Vein of Galen

… Base

of brain

… Internal

cerebral & basal veins … Straight sinus

6

Strokes „

Infarcts … Occlusions „

Thrombosis or embolism

„

Hemorrhage

„

Characterized by abrupt onset of a neurological deficit Small strokes can add up over time so the damage is less noticeable.

„

„

Aneurysm

Middle Cerebral Artery Syndrome

Middle Cerebral Artery Syndrome „

Contralateral hemiplegia/hemiparesis

„

Aphasia

Face/upper extremities

„

Contralateral kinesthia loss Contralateral visual field defect

„

Contralateral neglect Spatial disorders

„

Gerstmann syndrome

…

„ „

…

„

Optic radiation damage: lose quadrant or hemifield

…

…

…

If left hemisphere

If right hemisphere Finger agnosia, acalculia, right-left disorientation

Contralateral gaze paralysis …

FEF involvement „

Transient (1-2 days)

7

Anterior Cerebral Artery Syndrome

Anterior Cerebral Artery Syndrome „

Unilateral

„

… Contralateral

Bilateral … Unilateral

signs plus involvement of

hemiplegia/hemiparesis „

Lower extremity

… Contralateral

deficit „

Lower extremity

… Motor „

„

sensory

aphasia

If left hemisphere

Orbitofrontal cortex, limbic system, supplemental motor cortex, cingulate gyrus

… Loss

of initiative/spontaneity apathy … Memory/emotional disturbances … Akinetic mutism … Disturbance in gait & posture … Profound

Hemorrhage „ „ „ „ „

Hypertension Aneurysm Arteriovenous malformation Head trauma Bleeding disorder

„

Signs … Sudden „ „ „

onset of

Headache Neck stiffness Loss of consciousness

8

Aneurysm

Arteriovenous malformation

9