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CEREBROVASCULAR ANATOMY RITE REVIEW 2016 OUTLINE • External Carotid Artery • Internal Carotid Artery • MCA • ACA • Specific Anatomical Sites • Striatum and IC • Brainstem • Thalamus • Blood Supply of the Spinal Cord • Venous System HIGH-YIELD TOPICS (THESE TOPICS CAME UP REPEATEDLY FROM 2000-2014) • Specific Arteries (their origin and target they supply) • • Middle meningeal • Recurrent Artery of Huebner • Anterior choroidal Alexia without agraphia localization/PCA territory • CADASIL • CAA • Recognize carotid dissection on imaging • Recognize Laminar necrosis on imaging • Pituitary Apoplexy • Hypothermia after cardiac arrest • Anatomy of the deep venous sinus system RITE QUESTION 1A A 45 yo female hits her head while skiing. Initial examination shows a L scalp laceration, but the patient is alert, oriented and without focal deficits. Five hours later she is found obtunded, with unequal pupils, R hemiparesis, and cheynestokes respirations. What is the most likely diagnosis? A) Seizure/Post-Ictal State B) Epidural Hematoma C) Subdural Hematoma D) TBI with diffuse axonal injury RITE QUESTION 1B Head CT reveals the following. Which artery is most likely involved? A) Middle Meningeal Artery B) Middle Cerebral Artery C) Temporal Polar Artery D) Superficial Temporal Artery RITE QUESTION 1C The middle meningeal artery enters the skull via which foramen? A) Jugular Foramen B) Foramen Lacerum C) Foramen Magnum D) Foramen Spinosum RITE QUESTION 1D The middle meningeal artery is a branch off of what artery? A) Internal Carotid Artery B) External Carotid Artery C) Vertebral Artery D) Middle Cerebral Artery Explanation: The middle meningeal artery is a branch off the external carotid artery. It enters the skull via the foramen spinosum. It is just lateral to the foramen ovale in the sphenoid bone. An epidural hemorrhage is most commonly caused by trauma and can involve the middle meningeal artery. It is characterized by a lucid period and a delay prior to symptomatic development of a blood collection. In this patient, extensive bleeding in the left hemisphere led to right-sided long tract signs and uncal herniation. EXTERNAL CAROTID • Branches • • Superior thyroid a. Ascending Pharyngeal a. • • • • • • • • →posterior meningeal artery→foramen magnum Branches (neuromeningeal trunk) supply CN VII-XII Lingual a. Facial a. Occipital a. Posterior Auricular a. Superficial Temporal a. Maxillary a. • • → middle meningeal artery→foramen spinosum Branches (i.e., petrosal a.) supply CN VII Some Anatomists Like F’ing, Others Prefer S&M EXTERNAL CAROTID Meningeal Branches - Why are they important clinically (2 answers)? 1. Most common feeders of dural AV fistulas • AVF embolization can lead to CN palsies 2. Middle meningeal artery common cause of traumatic epidural hematoma RITE QUESTION 2A A 51 yo female with PMH significant for HTN and tobacco abuse presents for evaluation of 3 weeks of progressive diplopia and imbalance. On examination she has L mydriasis, poorly reactive to light, ptosis, and L hypotropia and exotropia on primary gaze. What is the next best test? A) MRI Brain B) MRA Circle of Willis C) CT Chest D) EEG RITE QUESTION 2B MRA Circle of Willis reveals a 6.5mm aneurysm of the posterior communicating artery. The posterior communicating artery is a branch of what major artery? A) Internal Carotid Artery B) Middle Cerebral Artery C) Posterior Cerebral Artery D) Anterior Cerebral Artery RITE QUESTION 2C MRA below reveals which anatomical variant of the Circle of Willis? A) Artery of Percheron B) Fetal Origin PCA C) Bovine Arch D) Accessory Middle Cerebral Artery RITE QUESTION 2C Explanations: A common variant of the circle of Willis is the persistent fetal origin of the posterior cerebral artery (PCA), when the PCA arises directly from the internal carotid artery. The Pcomm and anterior choroidal arteries arise from the internal carotid artery. The ACh feeds portions of the globus pallidus, putamen, and the posterior limb of the internal capsule. INTERNAL CAROTID • What are the divisions of the carotid artery (proximal to distal)? • Cervical • • Which branches arise from the cervical segment? NONE • Petrous/Lacerum • Cavernous • Clinoid/Supraclinoid INTERNAL CAROTID • Trace its course from extracranial to intracranial • Neck • Extracranial (None) • Foramen Lacerum • Intracranial Extradural (Caroticotympanic a, pterygoid a) • Enters Cavernous Sinus • Intracranial Interdural (Cavernous branches which anastamose with middle meningeal artery and supply CN III, IV, V, VI and menigohypophyseal trunk branches) • Exits Cavernous Sinus • Intracranial Intradural INTERNAL CAROTID • What are the 4 intracranial intradural (terminal) branches of the ICA? • • • • Opthalmic Superior Hypophyseal Artery Posterior Communicating Artery Anterior Choroidal Artery • What does the Anterior Choroidal Supply? • Posterior Limb of the Internal Capsule RITE QUESTION 3A A 68 yo male with PMH significant for HTN, HLD, DM, tobacco abuse and CAD s/p 4v CABG presents with 1 day of L-sided weakness and ataxia. MRI is below. What is most likely etiology? A. Cardioembolism B. Lipohyalinosis C. Vertebral Dissection D. Aortic Atheroscleotic Disease RITE QUESTION 3B The lacunar infarction pictured below is most likely related to lipohyalinosis of what small arteries? A. Thalamoperforators B. Basilar Perforators C. Meningeal Perforators D. Lenticulostriates RITE QUESTION 3 Explanation: The image shows classic lacunar infarctions involving the basal ganglia and internal capsule. Hypertension is the primary etiology for such lesions. Chronic hypertension is associated with arteriosclerosis (lipohyalinosis) affecting arteries of 50 microns to 200 microns in diameter. The most common regions affected are lenticulostriate vessels that supply the deep cerebral nuclei and internal capsule and arterial territories of the basis pontis and cerebellar hemispheres. MIDDLE CEREBRAL ARTERY • Nomenclature • Tree and trunk method • • • • Stem • Lenticulostriates Superior and Inferior Division • 78% bifurcation pattern • 12% Trifurcation • 10% no branching Prefrontal, Precentral, Central, Superior temporal, angular, etc In relation to anatomical landmarks • M1 (limen insula), M2 (insula), M3 (operculum), M4 (convexity). MIDDLE CEREBRAL ARTERY • Lenticulostriates • lentiform nucleus (putamen and pallidum), body of the caudate nucleus, and the (anterior) posterior limb of the internal capsule RITE QUESTION 4A A 7 yo male with no significant PMH presents with abnormal, hyperkinetic, non-stereotyped movements of the R hand and arm. At times the movements are severe. MRI shows the following. Which is the most likely involved structure explaining his abnormal movements? A. Anterior Limb of IC B. Thalamus C. Caudate Head D. Subthalamic Nucleus RITE QUESTION 4B The head of the caudate is supplied by which of the following arteries? A. Anterior choroidal artery B. Thalamoperforators C. Recurrent artery of Huebner D. Temporopolar artery ANTERIOR CEREBRAL ARTERY The FLAIR MRI image shows an area of high signal intensity in the distribution of the recurrent artery of Heubner. It is consistent with an infarct in this tissue. The recurrent artery of Heubner arises from the A1 segment of the anterior cerebral artery and supplies the anteroinferior portion of the caudate nucleus, the putamen, and the anterior limb of the internal capsule. REVIEW Head of the Caudate/Anterior Limb IC – Recurrent Artery of Huebner Posterior Limb IC/Striatum – Anterior Choroidal A/Lenticulostriates External Capsule/Claustrum – Trick Question: penetrating vessels from MCA on insular surface RITE QUESTION 5A A 52 yo male presents with 2 hours of dizziness, hoarsness, dysarthria, and R sided numbness. Exam is notable for small L ptosis and miosis, L ataxia on FTN and HTS, and loss of pin-prick sensation on the L face and R arm and leg. NIHSS is 6. He is not on any medications. There are no contraindications to the administration of IV-tPA by history. Which of the following tests must be checked prior to the administration of tPA? A) Echocardiogram B) Stool guiac C) INR D) Blood Glucose E) MRI Brain RITE QUESTION 5B Prior to the administration of IV-tPA, vital signs are: BP 210/105, HR 88, RR 16, O2 98% RA. Which of the following medications is most appropriate prior to administering tPA? A) IV heparin B) IV labetalol C) ASA/dipyridamole (aggrenox) D) IV Keppra RITE QUESTION 5C The patient’s clinical syndrome most likely localizes to what region of the brain or brainstem? A) L anterior limb of the internal capsule B) L lateral medulla C) R medial midbrain D) R angular gyrus BRAINSTEM Explanation: Hypoglycemia should always be excluded as occasionally this disorder can have signs of focal neurologic dysfunction and thereby mimic stroke. MRI of the brain, echocardiogram, and chest x-ray are not required tests prior to administration of t-PA. A stool guaiac test is not a standard requirement but might be considered in a patient with a possible history of GI bleeding. BRAINSTEM Explanation This patient presents with an acute stroke and is evaluated rapidly in an emergency setting. She appears to be a potential candidate for receiving IV t-PA based on her stroke scale, time window, and absence of contraindications to the drug; however, her blood pressure exceeds the guidelines for use of t-PA and IV labetalol would be indicated. Heparin and dipyridamole/ASA would not be indicated in this acute setting. BRAINSTEM BLOOD SUPPLY This patient has lateral medullary syndrome which usually is caused by occlusion of the posterior inferior cerebellar artery or vertebral dissection. It is characterized by ipsilateral facial anesthesia, contralateral body anesthesia, ipsilateral Horner syndrome, vertigo, dysarthria, ipsilateral cerebellar dysfunction, and hiccups. Right-sided tongue weakness would be associated with a medial medullary syndrome; tinnitus is associated with lateral pontomedullary lesions. Sixth nerve involvement and gaze palsies are associated with pontine lesions. BRAINSTEM BLOOD SUPPLY -PICA comes off vertebral artery -Vertebro-basilar junction is at pontomedullary junction -CN 6 passes between IAA and AICA -CN III passes between PCA and SCA -PCA branches in middle of interpeduncular cistern -Optic nerves/chiasm are ventral to ICA MIDBRAIN Cranial Medial - PCA, P1 (Paramedian A/As of Percheron, via posterior perforated substance) Lateral - PCA, P1 (Quadrigeminal A, Medial Posterior Choroidal A = long circumferentials) Caudal Medial - PCA, P1 (Paramedian A/As of Percheron, via posterior perforated substance) Lateral - PCA, P1 (Quadrigeminal A, Medial Posterior Choroidal A = long circumferentials) Tectum/Inf Colliculus - SCA (variable) PONS Cranial Medial – Basilar (Paramedian perforators) Lateral – Basilar (lateral pontine arteries = circumferentials) Tectum - SCA Caudal Medial - Basilar (paramedian perforators) Lateral - AICA MEDULLA Cranial Medial - Vertebral Artery (paramedian perforators) Postero-lateral – PICA Caudal Medial - ASA (paramedian perforators) Lateral - Vertebral Artery and PSA (circumferentials) Midbrain Weber, Benedikt, Claude – Third Nerve Hemiparesis Syndromes Weber syndrome Oculomotor Nerve – ipsilateral third nerve palsy Cerebral peduncle – contralateral hemiparesis Benedikt syndrome Oculomotor Nerve – ipsilateral third nerve Cerebral Peduncle – contralateral hemiparesis Red Nucleus/SubNig, SCP – movement disorders, ataxia Claude syndrome Oculomotor Nerve – ipsilateral third nerve Red Nucleus/SubNig, SCP – movement disorders, ataxia Nothnagel’s Syndrome usually tumors, not CVA. Symmetrical supranuclear opthalmoparesis and ataxia Lateral medullary syndrome (Wallenberg syndrome) • Crossed sensory only syndrome • • • Trigeminal Nucleus and Spinal Trigeminal Tract – ipsilateral facial loss of pain and temp Nucleus Solitarius – ipsilateral loss of taste Descending Sympathetic Fibers – ipsilateral Horners • Spinothalamic Tract – Contralateral body loss of P&T • • Nucleus Ambiguus – hoarseness/dysphagia Inferior Cerebellar Peduncle/Vestibular tracts – vertigo, ipsilateral ataxia Medial medullary syndrome (Dejerine syndrome) • Unilateral Sensorimotor stroke with tongue involvement • Medial rostral medulla; Rarely occurs in caudal medulla • Hypoglossal nucleus - ipsilateral tongue weakness • • Pyramidal tracts - Contralateral arm and leg weakness; face spared Medial lemniscus - Contralateral vibration, proprioception, and LT loss Hemimedullary syndrome (Babinski-Nageotte Syndrome) • Combination of the above RITE QUESTION 6A A 75 yo male is found unconscious by his wife 10 minutes after she left him alone in the living room. MRI on arrival is at right. Blood supply to the thalamus arises from which of the following arteries? A) ACA B) MCA C) PCA D) ICA RITE QUESTION 6B Which of the following anatomical variations can result in bilateral thalamic infarcts? A) Fenestrated basilar artery B) Accessory MCA C) Artery of Percheron D) Fetal origin PCA THALMUS 6 5 7 4 RITE QUESTION A 23 yo male undergoes resection of an abdominal yolk sac tumor. Which of the following interventions can prevent spinal cord ischemia during surgery? A)Continuous neuromuscular blockade B)Preoperative lumbar drain placement C)IV heparin infusion D)Foley catheter placement RITE QUESTION A lumbar drain system was not utilized during surgery and the operative course is complicated by hemorrhage and recurrent hypotension. Post-operatively, the patient is noted to have BLE weakness and a sensory level with loss of pain and temperature sensation below. Hypoperfusion through the Artery of Adamkiewicz is suspected. The sensory level described above is most likely at what level? A)T2 B)T9 C)L4 D)S5 SPINAL CORD The spinal cord receives its arterial blood supply via 1 anterior spinal artery (off the vertebral arteries) and 2 posterior spinal arteries (off the vertebral arteries or PICAs) SPINAL CORD There are 31 intersegmental arteries that provide arterial blood to the vertebral bodies, spinal roots, meninges, and ligaments = radicular or medullary arteries Intercostal (radicular a)→posterior ramus→branches to vertebrae/spinal roots/meninges/ligament/cord It is a matter of debate whether blood from the radicular arteries reaches the spinal cord SPINAL CORD However, several of the intersegmental arteries enlarge during gestation and contribute blood to the ASA and PSA (usually one or the other, not both) SPINAL CORD Cervical Spine Branches off the Subclavian • Vertebral As⇾C3 medullary feeder • Thyrocervical As⇾Ascending cervical A • Costocervical As⇾Deep cervical/Supreme intercostal As SPINAL CORD Upper and Middle Thoracic Spine No medullary feeders (intercostals only) Area at greatest risk for hypoperfusion related ischemia SPINAL CORD Low thoracic/Lumbosacral Spine Aorta⇾Artery of Adamkiewicz (Arteria Radicularis Magna)⇾Ascending and Descending branches⇾ASA • Enters at T9-T12 (62%) • Enters on L (73%) Internal Iliacs Lumbar, iliolumbar, middle, and lateral sacral As⇾Ascend with roots of cauda equina RITE QUESTION During an angiographic procedure to treat a dural AVF, an inexperienced operator accidentally injects onyx embolization material into the basal vein of rosenthal. The material will take which of the following paths to the right atrium? A)Basal vein of Rosenthal⇾Vein of Galen⇾Straight Sinus⇾Confluence⇾Transverse⇾Sigmoid⇾Jugular⇾RA B)Basal vein of Rosenthal⇾Inferior Sagittal⇾Straight⇾Confluence⇾Transverse⇾Sigmoid⇾Jugular⇾ RA C)Basal vein of Rosenthal⇾Great vein of Labbe⇾Superior sagittal sinus Sinus⇾Confluence⇾Transverse⇾Sigmoid⇾Jugular⇾RA D)Basal vein of Rosenthal⇾Vein of Galen⇾Straight Sinus⇾Confluence⇾Cavernour Sinus⇾Facial vein⇾Jugular⇾RA VENOUS SYSTEM