neuroscience blood supply of the central nervous system dr. michael p. gillespie 1

NeuroscienceBlood Supply of the Central Nervous System

Dr. Michael P. Gillespie

1

Blood Supply To the CNS

The central nervous system is one of the most metabolically active systems in the body.

A brief interruption of blood flow can result in serious neurological disturbances.

Dr. Michael P. Gillespie2

Level of Blood Flow

The normal blood flow to the brain is about 50 mL/100g of brain tissue/min.

Ischemic penumbra is a blood flow of 25 mL/100g of brain tissue/min. This level is dangerously low and can lead to loss of brain cells.

A blood flow of 8 mL/100g of brain tissue/min leads to an almost complete loss of functional neurons.

Consciousness is lost within 10 seconds of cessation of blood supply to the brain.


Arterial Supply of the Brain

Internal Carotid Arteries

Vertebral Arteries


Branches of the Internal Carotid Arteries

Opthalmic artery

Posterior communicating artery

Anterior choroidal artery

Anterior cerebral artery

Middle cerebral artery


Vertebro-Basilar Circulation

The two vertebral arteries merge to form the basilar artery.

This arterial system supplies the medulla, pons, mesencephalon, and cerebellum.


Vertebral Artery Branches

Anterior spinal artery

Posterior inferior cerebellar artery

Posterior spinal artery


Basilar Artery Branches

Anterior inferior cerebellar artery

Labyrinthine (internal Auditory) artery

Pontine arteries

Superior cerebellar artery

Posterior cerebral arteries


Cerebral Arterial Circle (Circle of Willis)


Venous Drainage of the Brain

Sinuses

Cerebral veins


Sinuses

Superior sagittal sinus

Inferior sagittal sinus

Transverse sinus

Confluence of sinuses

Cavernous sinuses

Sphenoparietal sinuses


Cerebral Veins

Superficial cerebral veins

Deep cerebral veins


Venous Return


Spinal Cord Arteries

Posterior spinal arteries

Anterior spinal artery

Spinal medullary and radicular arteries


Spinal Cord Veins

Anteromedian spinal vein

Anterolateral spinal veins

Posteromedian spinal vein

Posterolateral spinal veins


Stroke (Cerebrovascular accident CVA)

Diseases involving the blood vessels that supply the brain can cause stroke.

Blockage of vessels (occlusive stroke). Emboli Thrombus

Bleeding from vessels (hemorrhagic stroke). Aneurysm Atrial-Venous Malformation AVM

A ruptured aneurysm can cause a hematoma (blood clot) to form.

The hematoma occludes blood flow to adjacent tissue causing brain ischemia.


Stroke continued…

This can result in syncope.

If the symptoms of ischemia last for less than 24 hours it is referred to as a transient ischemic attack (TIA).

TIAs are usually caused by emboli. They are sometimes caused by atherosclerotic plaques.

If the neurological deficits persist for at least 24 hours it is referred to as a stroke.


Risk Factors

Old age

High blood pressure

Previous stroke or TIA

High cholesterol

Tobacco smoking

Atrial fibrillation


Rehabilitation

Rehabilitation should start as quickly as possible.

Joint R.O.M.

Strength

Re-learning functional tasks.

Activities of daily living.

Speech and language therapy.

Lasts a few days to over a year.


Cerebral Vascular Syndromes

The cerebral cortex is supplied by the following arteries: Anterior cerebral artery Middle cerebral artery Posterior cerebral artery


Anterior Cerebral Artery Syndrome

Damages the precentral gyrus which results in contralateral paralysis (hemiplegia) (mainly of the leg).

Occlusion of both anterior cerebral arteries produces bilateral paralysis.

Occlusion of the post central gyrus results in impaired sensation (mainly in the leg).


Middle Cerebral Artery Syndrome

Occlusion of this artery results in contralateral hemiplegia, predominantly in the upper extremities and face.

If the left hemisphere is involved, aphasia (disturbances in speech) may occur because the speech centers are located laterally in this hemisphere.


Posterior Cerebral Artery Syndrome

Occlusion of the posterior cerebral artery results in hemianopsia.


Hemianopsia

Both visual fields intact

Left homonymous hemianopsia


Hemianopsia

Binasal hemianopsia

Bitemporal hemianopsia


Midbrain Vascular Syndromes

Weber’s Syndrome

Claude’s Syndrome

Parinaud’s Syndrome

Benedikt’s Syndrome

Superior Cerebellar Artery Syndrome


Weber’s Syndrome

Also called medial midbrain syndrome

Occlusion of branches of the posterior cerebral artery.

Ipsilateral paresis of adduction and vertical gaze.

Pupillary dilation (damage to occulomotor nerve on the side of the lesion).

Hemiparesis or Hemiplegia (more often) of the contralateral face, arm, and leg.


Claude’s Syndrome

A brainstem stroke syndrome.

Ipsilateral oculomotor paresis (oculomotor nerve palsy).

Contralateral ataxia and tremor.

Contralateral hemiparesis.

Contralateral hemiplegia.

Affects the lower face, tongue and shoulder.


Parinaud’s Syndrome

A midbrain syndrome.

Also called gaze palsy syndrome and sylvian aqueduct syndrome.

Impaired upward vertical gaze.

Loss of pupillary light reflex.

Henri Parinaud is the father of French ophthalmology.


Benedikt’s Syndrome

A midbrain lesion.

Oculomotor nerve paresis.

Ataxia.

Hemiparesis (more often) or hemiplegia of the contraleteral face, arm, and leg.

Similar to Weber’s Syndrome.


Superior Cerebellar Artery Syndrome

Analgesia and thermoanesthesia on the ipsilateral side of the face (trigeminal nerve damage).

Ipsilateral Horner’s Syndrome.

Contralateral loss of sensations of pain and temperature (spinothalamic tract).

Ipsilateral limb and gait ataxia.


Horner’s Syndrome

Constriction of the ipsilateral pupil (miosis).

Drooping of the upper eyelid (ptosis).

Sinking in of the eyeball (enophthalmos).

Decreased sweating (anhidrosis) on the side of the face affected.


Pontine Vascular Syndromes

Loss of blood supply to regions of the Pons.

Upper motor neuron paralysis.

Facial paralysis.


Incidence


Necrosis


Subdural Hematoma


Parenchymal Bleed with Hematoma


neuroscience blood supply of the central nervous system dr. michael p. gillespie 1

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