Blood Supply of Brain & Spinal Cord (RCSI) 2024 PDF

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Brain blood vessels and intracerebral bleeds Class Year 2 Semester 1 Course Medicine Lecturer Dr. Vijayalakshmi S B Date 06/11/2024 LEARNING OUTCOMES Describe the blood supply to the brain and spi...

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Brain blood vessels and intracerebral bleeds Class Year 2 Semester 1 Course Medicine Lecturer Dr. Vijayalakshmi S B Date 06/11/2024 LEARNING OUTCOMES Describe the blood supply to the brain and spinal cord Identify the areas supplied by individual arteries Describe the Circle of Willis Define the term “stroke”, and differentiate the main causes of ischaemic and haemorrhagic strokes. Explain the effect of focal lesions caused by strokes in major cortical functional areas  BLOOD SUPPLY TO THE BRAIN A. Anterior system: Internal carotid arteries→ Most of forebrain except occipital lobe B. Posterior system: Vertebro-basilar arteries→ Spinal cord, brainstem, cerebellum and occipital lobes C. The two systems/circulations are connected via Circle of Willis (green zone in the figure) 3  BLOOD SUPPLY Internal carotid arteries Vertebral arteries  BLOOD SUPPLY Where do the internal carotid arteries arise from ? How do they pass up the neck? How do they enter the skull? Where do the vertebral arteries arise from How do they pass up the neck? How do they enter the skull? VERTEBROBASILAR SYSTEM Two Vertebral arteries (L+R) From the subclavian artery Ascend in transverse foramina Enter foramen magnum Release postero-inferior cerebellar artery (PICA) Release posterior and anterior spinal arteries The two vertebral arteries merge into one Basilar artery  VERTEBRAL ARTERIES AND SPINAL CORD Anterior spinal arteries unite to form a single anterior spinal artery Two posterior spinal arteries travel vertically Radicular Posterior spinal Anterior spinal Segmental  8 BLOOD SUPPLY TO SPINAL CORD From vertebral artery or radicular arteries From vertebral artery, PICA or radicular arteries  VERTEBRAL ARTERIES AND SPINAL CORD Spinal arteries are supplemented by Radicular arteries enter intervertebral foramina arising from Segmental arteries. Artery of Adamkiewicz in the lower thoracic or upper lumbar region Branches of the basilar artery Basilar artery formed at the ponto-medullary junction AICA (Anterior Inferior Cerebellar Arteries) Labyrinthine arteries Superior PCA Pontine arteries cerebellar Superior cerebellar arteries Tentorium cerebelli Posterior cerebral arteries Terminal branches Communicate to ICA via posterior communicating arteries Pontine AICA ALPS JC Holland Pontomedullary junction Figure 7.3 Arteries on the base of the brain. The arterial system has been injected with a red dye. Downloaded from: S tud entCon sult (on 6 No vembe r 2 007 12:00 PM) © 2005 Elsevier Figure 7.6 Vertebral angiograms. Radio-opaque material has been introduced into the vertebral artery in order to display its intracranial course and distribution. (A) Lateral view; (B) anteroposterior (Towne's) view. (Courtesy of Professor P D Griffiths) Downloaded from: S tud entCon sult (on 6 No vembe r 2 007 12:00 PM) © 2005 Elsevier INTERNAL CAROTID ARTERY Internal Carotid artery  THE CAROTID SIPHON: ANGIOGRAM 1) Cervical part of ICA Enters carotid foramen/canal 2) Passes through the carotid canal as the petrous part of ICA 3) Opening into top part of foramen lacerum and travels through cavernous sinus (cavernous part) 4) Cerebral part of ICA joins 4 circle of Willis 3 2 1  Internal carotid angiogram Lateral view Antero-posterior view Figure 7.5 Carotid angiograms. Radio-opaque material has been introduced into the internal carotid artery in order to display its intracranial course and distribution. (A) Lateral view; (B) anteroposterior (Towne's) view. (Courtesy of Professor P D Griffiths) Downloaded from: S tud entCon sult (on 6 No vembe r 2 007 12:00 PM) © 2005 Elsevier  BRANCHES OF THE INTERNAL CAROTID ARTERY Ophthalmic Through the optic canal to the eye Anterior choroidal artery – To choroid plexus, enters the tip of the inferior horn of the lateral ventricle – Also supplies optic chiasma, optic tract, lateral geniculate body (thalamus)+ – and retrolentiform part of the internal capsule – Branch to the pituitary gland Posterior communicating artery 2 terminal branches Anterior cerebral (joined by the anterior communicating arteries) Middle cerebral Anterior cerebral artery Anterior communicating artery Internal Carotid artery Middle cerebral artery Posterior communicating artery Cerebral Arterial Circle (Circle of Willis) Anterior communicating artery Anterior cerebral artery Internal carotid artery Middle cerebral artery Posterior communicating artery Posterior cerebral artery  CEREBRAL ARTERIAL CIRCLE (CIRCLE OF WILLIS) Anterior cerebral arteries, A.Comm artery, internal carotid arteries, P.Comm artery, posterior cerebral arteries. Anterior cerebral artery  Anterior cerebral artery Orbital surface of frontal lobe Medial aspect of hemisphere (except occipital lobe) Upper border of frontal & parietal lobes Lower limb Perineum Micturition & defecation Medial striate arteries to basal ganglia and supply anterior limb and genu of internal capsule 24 ANTERIOR CEREBRAL ARTERY  Middle cerebral artery Lateral fissure Lateral aspect of hemisphere (except anterior cerebral strip & occipital lobe)  Middle cerebral artery Lateral fissure Lateral aspect of hemisphere (except anterior cerebral strip & occipital lobe) Thorax Upper limb Head & neck Speech & auditory  MIDDLE CEREBRAL ARTERY Largest artery Passes to lateral fissure and then Lateral aspect of the hemisphere Supplies the lateral cerebral hemispheres: Lateral aspects of the frontal lobe, Parietal lobe and temporal lobe Medially supplies the anterior temporal lobe Supplies speech (Brocas & Wernickes) and auditory areas Lateral striatal or lenticulostriate arteries to the basal ganglia and internal capsule  Posterior cerebral artery Occipital lobe Infero-medial temporal lobe Usually, terminal branch of the basilar Rarely, may receive more (or all) blood supply via posterior communicating artery (as in the embryo) Blood supply of the central cerebral areas What are they? Basal ganglia, internal capsule etc. Anterior choroidal & striate arteries JC Holland Downloaded from: S tud entCon sult (on 6 No vembe r 2 007 12:55 PM) © 2005 Elsevier INTERNAL CAPSULE Anterior limb – frontopontine fibres, thalamus to prefrontal Genu – corticobulbar fibres Posterior limb – corticospinal & sensory fibres & corticobulbar fibres Retrolentiform – (fibres passing to auditory and visual cortex) Striate arteries There are various names, especially in older books  Lenticulostriate, thalamostriate, long central artery Medial striate arteries From anterior cerebral Internal capsule - anterior limb and genu Nearby basal ganglia Head of caudate, medial globus pallidus, anterior hypothalamus Lateral striate arteries From middle cerebral & anterior choroidal arteries Internal capsule – all! Nearby basal ganglia Putamen Central branches of posterior cerebral… Plus some from posterior communicating Thalamus and third ventricle Blood supply of the central cerebral areas  STROKE Sudden development of focal neurological deficits that are usually related to impaired cerebral blood flow Type: Ischaemic Haemorrhagic Common causes: spontaneous cerebrovascular accidents (CVA) Cerebral thrombosis Cerebral haemorrhage Cerebral embolism Subarachnoid haemorrhage TIAs (Transient Ischaemic Attacks): neurologic symptoms due to ischaemia (carotid or vertebrobasilar stenosis). Last only a few minutes (but an hour). C/F staggering, dizziness, light-headedness, fainting, and paraesthesia. TIAs are at risk of MI or ischaemic stroke. STROKE  How is blood supply to the brain is affected Definition Stroke The sudden death of brain cells due to lack of oxygen, caused by blockage of blood flow or rupture of an artery to the brain Previously known as a CVA (cerebrovascular accident) Ischaemic vs Haemorrhagic Block vs bleed Hypertension Thrombosis (clot in cerebral arteries) Ischaemia of Rupture of blood vessels the brain cells Embolism – Aneursym generated in A blood vessel outside the brain Trauma C Connolly/ J Holland FAST...  STROKE Cerebral hemispheres – contralateral symptoms Anterior cerebral Contralateral hemiplegia and anaesthesia – where? Middle cerebral Contralateral hemiplegia and anaesthesia – where? ± aphasia Posterior cerebral Contralateral hemianopia Vertebrobasilar – a mix of contralateral & ipsilateral symptoms Brainstem… depends on what has been discussed or not! Medial medullary syndrome Lateral medullary syndrome (part of PICA) Cerebellar hemispheres – ipsilateral symptoms Cerebellar signs (loss of balance & coordination) Superior cerebellar, AICA, PICA**  MIDDLE CEREBRAL ARTERY Bleed/ thromboembolism – contralateral motor sensory loss (sparing lower limb and perineum) +/- speech deficit ( If the dominant hemisphere is involved) Lateral striatal or lenticulostriate arteries to the basal ganglia and internal capsule Main supply to the internal capsule  PICA syndrome Lateral medullary syndrome of Wallenberg… Lateral medulla is supplied by PICA Nucleus ambiguus Vestibulocochlear nuclei Palate, pharynx, larynx Vertigo, nystagmus, tinnitus Trigeminal nucleus (spinal) Sympathetic (descending) Ipsilateral pain & Ipsilateral Horner’s syndrome temperature loss from face Ptosis, meiosis, anhydrosis Spinal lemniscus Contralateral pain and temperature from the body J Holland / A McGarvey  PICA SYNDROME (LATERAL MEDULLARY SYNDROME, WALLENBERG SYNDROME) Contralateral loss of pain and temperature-anterolateral system Ipsilateral loss of pain and temperature from face -spinal trigeminal tract and nucleus Vertigo and nystagmus - vestibular nucleus Loss of taste from ipsilateral ½ of tongue - solitary tract and nucleus (VII and IX nerves) Hoarseness/dysphagia - nucleus ambiguus (IX, X, XI nerves)  MEDIAL MEDULLARY SYNDROME Medial part of the medulla is supplied by the vertebral artery Signs & Symptoms Contralateral hemiparesis – why? Corticospinal tracts in pyramids Contralateral impaired sensations of position and movement, tactile discrimination – why? Medial lemniscus – dorsal columns Ipsilateral paralysis of tongue - why? Hypoglossal nerve & nucleus MEDIAL MEDULLARY SYNDROME May be additional cranial nerve nuclei involved SUBARACHNOID HAEMORRHAGE  46 VENOUS DRAINAGE OF THE BRAIN Drained by a system of veins that empty into the dural sinuses Sinuses empty into the right and left internal jugular veins Cerebral veins – divided into superficial and deep cerebral veins Superficial cerebral veins – superficial middle cerebral vein, superior anastomotic vein of Trolard and inferior anastomotic vein of Labbe Deep cerebral veins – great cerebral vein of Galen, basal vein of Rosenthal and internal cerebral vein 47  48 VENOUS DRAINAGE OF SPINAL CORD Some video links… Anterior cerebral artery stroke https://youtu.be/1mdXNDWL8q0 Middle cerebral artery stroke (N.B. calls lateral striate arteries the lenticulostriate arteries) https://youtu.be/OwPhJGITFKc Posterior cerebral artery stroke https://youtu.be/u1ml2sfao8o Internal capsule stroke https://youtu.be/EgFuykdETbw JC Holland  PRACTICE QUESTIONS THANK YOU