Download Cerebrovascular Anatomy 2016

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