Neuroscience Blood 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. Gillespie 2

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. Dr. Michael P. Gillespie 3

Arterial Supply of the Brain  Internal Carotid Arteries  Vertebral Arteries Dr. Michael P. Gillespie 4

Branches of the Internal Carotid Arteries  Opthalmic artery  Posterior communicating artery  Anterior choroidal artery  Anterior cerebral artery  Middle cerebral artery Dr. Michael P. Gillespie 5

Vertebro-Basilar Circulation  The two vertebral arteries merge to form the basilar artery.  This arterial system supplies the medulla, pons, mesencephalon, and cerebellum. Dr. Michael P. Gillespie 6

Vertebral Artery Branches Anterior spinal artery Posterior inferior cerebellar artery Posterior spinal artery Dr. Michael P. Gillespie 7

Basilar Artery Branches  Anterior inferior cerebellar artery  Labyrinthine (internal Auditory) artery  Pontine arteries  Superior cerebellar artery  Posterior cerebral arteries Dr. Michael P. Gillespie 8

Cerebral Arterial Circle (Circle of Willis) Dr. Michael P. Gillespie 9

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Venous Drainage of the Brain  Sinuses  Cerebral veins Dr. Michael P. Gillespie 15

Sinuses  Superior sagittal sinus  Inferior sagittal sinus  Transverse sinus  Confluence of sinuses  Cavernous sinuses  Sphenoparietal sinuses Dr. Michael P. Gillespie 16

Cerebral Veins  Superficial cerebral veins  Deep cerebral veins Dr. Michael P. Gillespie 17

Venous Return Dr. Michael P. Gillespie18

Spinal Cord Arteries  Posterior spinal arteries  Anterior spinal artery  Spinal medullary and radicular arteries Dr. Michael P. Gillespie 19

Spinal Cord Veins  Anteromedian spinal vein  Anterolateral spinal veins  Posteromedian spinal vein  Posterolateral spinal veins Dr. Michael P. Gillespie 20

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. Dr. Michael P. Gillespie21

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. Dr. Michael P. Gillespie22

Risk Factors  Old age  High blood pressure  Previous stroke or TIA  High cholesterol  Tobacco smoking  Atrial fibrillation Dr. Michael P. Gillespie23

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. Dr. Michael P. Gillespie24

Cerebral Vascular Syndromes  The cerebral cortex is supplied by the following arteries:  Anterior cerebral artery  Middle cerebral artery  Posterior cerebral artery Dr. Michael P. Gillespie25

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). Dr. Michael P. Gillespie26

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. Dr. Michael P. Gillespie27

Posterior Cerebral Artery Syndrome  Occlusion of the posterior cerebral artery results in hemianopsia. Dr. Michael P. Gillespie28

Hemianopsia Both visual fields intact Left homonymous hemianopsia Dr. Michael P. Gillespie29

Hemianopsia Binasal hemianopsia Bitemporal hemianopsia Dr. Michael P. Gillespie30

Midbrain Vascular Syndromes  Weber’s Syndrome  Claude’s Syndrome  Parinaud’s Syndrome  Benedikt’s Syndrome  Superior Cerebellar Artery Syndrome Dr. Michael P. Gillespie31

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. Dr. Michael P. Gillespie32

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. Dr. Michael P. Gillespie33

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. Dr. Michael P. Gillespie34

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. Dr. Michael P. Gillespie35

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. Dr. Michael P. Gillespie36

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. Dr. Michael P. Gillespie37

Pontine Vascular Syndromes  Loss of blood supply to regions of the Pons.  Upper motor neuron paralysis.  Facial paralysis. Dr. Michael P. Gillespie38

Incidence Dr. Michael P. Gillespie39

Necrosis Dr. Michael P. Gillespie40

Subdural Hematoma Dr. Michael P. Gillespie41

Parenchymal Bleed with Hematoma Dr. Michael P. Gillespie42