Cerebral Vascular Anatomy

Dr.Mohamed Ashraf Zaitoun, MDInterventional Radiology Lecturer, Zagazig University,

EgyptFINR-Switzerland

Knowing as much as possible about your enemy precedes successful battle and

learning about the disease process precedes successful management

Anterior Circulation

Internal Carotid Artery (ICA)a) Originb) Portions :Cervical PortionPetrous PortionCavernous PortionIntradural Portion

a) Origin :-ICA originates in the neck as a terminal branch

of the common carotid artery (CCA) at the level of the thyroid cartilage (i.e. C3 or C4 vertebrae)

-It terminates intracranially at the inferior surface of the brain by dividing into anterior & middle cerebral arteries

-Lateral 2D view following left common carotid artery injection , note the atherosclerotic plaque involving the proximal internal carotid artery1-Common carotid A.2-Internal carotid A.3-External carotid A.5-Occipital artery7-Superior thyroid A.

8-Lingual-facial artery trunk

1-Common Carotid Artery2-Internal Carotid Artery3-Ascending pharyngeal Artery4-Occipital Artery5-Superficial Temporal Artery6-Middle cerebral Artery7-Anterior cerebral Artery8-Middle meningeal Artery9-Maxillary Artery10-Facial Artery11-Lingual Artery12-External Carotid Artery13-Superior Thyroid Artery

b) Portions :1-Cervical Portion-Extends from the bifurcation of the CCA to the

skull base-In this section , the artery lies in the carotid

sheath with the internal jugular vein (IJV) laterally , the vagus nerve & the cranial root of the accessory nerve “XIth” (which travels with Xth) run posteriorly & between these vessels

2-Petrous Portion-The petrous segment of the internal carotid

artery consists of a vertical and a horizontal portion

-It enters the skull base at the exocranial opening of the carotid canal , ascends approximately 1 cm (vertical portion) and then turns anteromedially until it enters the intracranial space at the foramen lacerum (horizontal portion)

-Branches :Angiographically , branches of the petrous

internal carotid artery are uncommon but at least three possible branches are worth remembering :

1-Caroticotympanic Branch2-Mandibulovidian Trunk3-Variant Stapedial Artery

3-Cavernous Segment-Following its petrous passage , the ICA enters the

cavernous sinus and lies medial to the Gasserian ganglion , the ophthalmic division of the trigeminal nerve and the oculomotor , trochlear and abducens cranial nerves

-It runs horizontally forwards and then turns superiorly and medial to the anterior clinoid process , passes through the dural ring and enters its final intradural and supraclinoid course

-Branches : 3 Groups1-The Meningohypophyseal Trunk (MHT)2-The Inferolateral Trunk (ILT)3-The Capsular Arteries of McConnell

4-Intradural Portion-The supraclinoid portion of the ICA is intradural , the

artery having entered the subarachnoid space after crossing the dural ring medial to the anterior clinoid process

-It turns posteriorly and runs lateral to the optic nerve to terminate by dividing into anterior and middle cerebral arteries

-From this portion originates successfully : the ophthalmic artery , the superior hypophyseal artery , the PCOM and the anterior choroidal arteries

Intracranial superior view of the right sellar and parasellar region , AC: anterior clinoid process , ICA: internal carotid artery , LT: lamina terminalis , ON: optic nerve , OlN: olfatory nerve , SW: sphenoid wing , TS: tubercullum sellae

Anterior Cerebral Artery

a) Origin :-The ACA originates below the anterior

perforating substance , lateral to the optic chiasm as one of the terminal branches of ICA

-Frontal view of the anterior (carotid) intracranial circulation1 internal carotid artery - cervical segment2 internal carotid artery - vertical petrous segment3 internal carotid artery – horizontal petrous segment4 presellar segment (C5) internal carotid artery9 ophthalmic artery10 and 11 supraclinoid segment internal carotid artery13 anterior choroidal artery14 internal carotid artery bifurcation15 A1 segment of anterior cerebral artery16 medial lenticulostriate arteries17 recurrent artery of Heubner18 A1-A2 junction anterior cerebral artery19 anterior communicating artery20 proximal A2 segment anterior cerebral artery21 callosomarginal branch of anterior cerebral artery28 pericallosal branch of anterior cerebral artery31 M1 segment of middle cerebral artery32 lateral lenticulostriate arteries33 bifurcation/trifurcation of middle cerebral artery34 anterior temporal lobe branches of middle cerebral43 sylvian point44 opercular branches of middle cerebral artery45 sylvian(insular) branches of middle cerebral artery

-Top down view (superior to inferior) of the skull baseBLACK KEY

5 meningohypophyseal trunk6 horizontal (C4) intracavernous ICA

7 inferolateral trunk9 ophthalmic artery

12 PCOM13 anterior choroidal artery

14 ICA bifurcation15 A1 segment of ACA

19 ACOM20 proximal A2 segment ACA

21 callosomarginal branch of ACA 28 pericallosal branch of anterior cerebral

31 M1 segment of MCA33 bifurcation/trifurcation of MCA

34 anterior temporal lobe branches of MCA35 orbitofrontal branch of MCA

45 sylvian(insular) branches of MCA RED KEY1 vertebral artery2 PICA3 basilar artery4 AICA5 superior cerebellar artery6.1 P1 segment PCA6.2 P2 segment PCA8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA14 vertebral-basilar junction16 pontine perforators17 anterior spinal artery

b) Segmental Anatomy :-A1 segment : from the ICA bifurcation to the ACOM

14mm in length-A2 segment : from ACOM to the origin of the

callosomarginal artery (the junction of the rostrum and genu of the corpus callosum)

-A3 segment : distal to the origin of the callosomarginal artery “a.k.a. pericallosal artery “ (extends around the genu until the artery turns sharply posteriorly)

-A4 and A5 segments : above the corpus callosum are separated by the plane of the coronal fissure

1-ICA , 2-MCA , 3-ACA (A1) , 4-ACA (A2) , Arrow : ACOM

1-Straight sinus , 2-Internal cerebral vein , 3-ACA (A2) , 4-ACA (A3) , 5-Callosomarginal artery , 6-Pericallosal artery , 7-Corpus callosum

c) Branches :1-A1 Section2-A2 Section3-A3 Section4-A4 & A5 Sections

1-A1 Section : Precommunicating Arterya) Lenticulostriate Arteriesb) Recurrent Artery of Heubnerc) Anterior Communicating Artery

Anterior circle of Willis showing lenticulostriate arteries arising from the anterior cerebral arteries (M medial group) and middle cerebral artery (L lateral group) , On the left , the anterior choroidal (AChA) and on the right the recurrent artery of Heubner (RaH) , note that anterior perforating arteries also arise from the anterior communicating artery

2-A2 Section :-The main branches arise from this section are :1-Orbitofrontal artery of the ACA2-Frontopolar Artery

1-Orbitofrontal artery2-Frontopolar artery 3Callosomarginal artery

4-Pericallosal artery

3-A3 Section :-Distal to the origin of the callosomarginal artery or

the genu , if the callosomarginal artery can’t be identified

-It gives a group of four arterial branches :1-Anterior internal frontal2-Middle internal frontal3-Posterior internal frontal4-Paracentral artery

(1) Orbitofronal , (2) Frontopolar , (3) Anterior internal forntal , (4) Middle internal frontal , (5) Posterior internal frontal , (6) paracentral , (7) Superior parietal , (8) Inferior parietal , (9) Callosomarginal , (10) Pericallosal

4-A4 & A5 Sections :-In its A4 (or A5) final section , the pericallosal

artery runs posteriorly over the body of the corpus callosum in the cistern of that name

-It terminates & anastomoses with the posterior pericallosal artery that arises from the PCA

Middle Cerebral Artery

1-Origin :-The MCA arises as the lateral terminal branch of

the ICA

2-Segmental Anatomy :a) M1 :-Horizontal , from the ICA to the lateral fissure

b) M2 :-Insular , the upper & lower trunk arteries thus formed -Designates the branches located inside the Sylvian

fissurec) M3 :-Opercular , denominates the branches located

between the top of the Sylvian fissure and the cerebral cortex

d) M4 :-Cortical , refers to arterial branches on the surface of

the cerebral cortex

(1) MCA bifurcation (genu) , (2) MCA (M1) , (3) ICA (RT side) , (4) ACA (A1) , (5) ICA (LT side) , (6) MCA (LT side)

(1) MCA , M4 , (2) MCA (M3) , (3) MCA (M2) , (4) MCA (M1) , (5) ICA (LT side) , (6) MCA (LT side)

(1) MCA (M4) , (2) MCA (M3) , (3) MCA (M2) , (4) MCA (M1) , (5) LT ICA , (6) LT MCA , (7) Basilar artery , (8) PCA

-2D frontal view following right ICA injection , the appearance of the carotid circulation is normal , Note the early bifurcation of MCA (normal variant)1 ICA – cervical segment2 ICA – vertical petrous segment3 ICA – horizontal petrous segment4 presellar (Fischer C5) ICA6 horizontal (Fischer C4) intracavernous ICA9 ophthalmic artery10 & 11 proximal and distal supraclinoid segment ICA12 posterior communicating artery13 anterior choroidal artery14 internal carotid artery bifurcation15 A1 segment of ACA17 recurrent artery of Heubner20 proximal A2 segment ACA21 callosomarginal branch ACA28 pericallosal branch of ACA31 M1 segment of MCA32 lateral lenticulostriate arteries33 bifurcation/trifurcation of MCA34 anterior temporal lobe branches of MCA35 orbitofrontal branch of MCA43 sylvian point44 opercular branches of MCA

45 sylvian (insular) branches of MCA

-Frontal 3D view following right internalcarotid artery injection , these views show the normal appearance of the intracranial internal carotid artery circulation. The proximal A2 segments of the anterior cerebral arteries have been intentionally removed from the images1 ICA – cervical segment2 ICA – vertical petrous segment3 ICA – horizontal petrous segment4 presellar (Fischer C5) ICA6 horizontal (Fischer C4) intracavernous ICA8 anterior genu (Fischer C3) intracavernous IAC9 ophthalmic artery10 & 11 proximal and distal supraclinoid segment ICA13 anterior choroidal artery14 ICA bifurcation15 A1 segment of ACA20 proximal A2 segment ACA22 orbitofrontal branch of ACA31 M1 segment of MCA33 bifurcation/trifurcation of MCA43 sylvian point44 opercular branches of MCA45 sylvian (insular) branches of MCA

-Lateral 2D view following CA injection in the late arterial phase-The triangle placed on the image is called the sylvian triangle , this represents the geometric representation of the MCA overlying the insular cortex-Alteration in the shape of this triangle can indicate mass displacements of the (MCA) branches

1 ICA – cervical segment2 ICA – vertical petrous segment

3 ICA – horizontal petrous segment4 presellar (Fischer C5) segment ICA

6 horizontal (Fischer C4) intracavernous ICA

8 anterior genu (Fischer C3) intracavernous ICA

9 ophthalmic artery35 orbitofrontal branch of MCA

36 operculofrontal branches of MCA37 pre-central branch(es) of MCA

38 central rolandic branches of MCA39a anterior parietal branch of MCA39p posterior parietal branch of MCA

40 angular artery42m middle temporal branches of MCA42p posterior temporal branches of MCA

43 sylvian point44 opercular branches of MCA

3-Branches :-Can be classified into two groups :a) Deep (perforator) b) Superficial (cortical)

a) Deep (Perforating) Branches :-Arise from the superior surface of the M1

segment-They are grouped as the medial & lateral

lenticulostriate arteries

-2D frontal view following left ICA injections , these images show an aneurysm in the region of the left MCA bifurcation/trifurcation2 ICA – vertical petrous segment3 ICA – horizontal petrous segment4 presellar (Fischer C5) ICA6 horizontal (Fischer C4) intracavernous ICA8 anterior genu (Fischer C3) intracavernous ICA9 ophthalmic artery10 & 11 proximal and distal supraclinoid segments ICA12 PCOM13 anterior choroidal artery14 ICA bifurcation15 A1 segment of ACA18 A1-A2 junction ACA20 proximal A2 segment ACA21 callosomarginal branch of ACA22 orbitofrontal branch of ACA28 pericallosal branch of ACA31 M1 segment of MCA32 lateral lenticulostriate arteries33 bifurcation/trifurcation MCA34 anterior temporal lobe branches MCA35 orbitofrontal branch MCA43 sylvian point44 opercular branches MCA45 sylvian (insular) branches MCA

-2D frontal view following right ICA injection , these views show a small aneurysm projecting inferiorly in the region of the right MCA bifurcation1 ICA – cervical segment2 ICA – vertical petrous segment3 ICA – horizontal petrous segment4 presellar (Fischer C5) segment ICA8 anterior genu (Fischer C3) intracavernous ICA9 ophthalmic artery10 & 11 proximal and distal supraclinoid segments ICA13 anterior choroidal artery14 ICA bifurcation15 A1 segment of ACA18 A1-A2 junction ACA20 proximal A2 segment ACA21 callosomarginal branch of ACA22 orbitofrontal branch of ACA23 frontopolar branch of ACA28 pericallosal branch of ACA31 M1 segment of MCA32 lateral lenticulostriate arteries33 bifurcation/trifurcation of MCA35 orbitofrontal branch of MCA43 sylvian point44 opercular branches MCA45 sylvian (insular) branches of MCAAn aneurysm

b) Superficial (Cortical) branches :-Supply a considerable proportion of the superficial

hemispheric cortex*Arteries to the Frontal lobe :-These run superiorly after leaving the fissure ,

from anterior to posterior :1-Orbitofrontal artery of the MCA2-Prefrontal artery (supplies Broca’s area)3-Precentral artery (or Pre-Rolandic artery of Sillon)4-Central artery (or artery of the Rolandic fissure)

- Lateral 2D view followinginternal carotid artery injection midarterial phase , non-filling of the anterior cerebral artery allows for an unobtrusive view of the more distal (mca) branches. A template typelabeling of the distal middle cerebralartery branches allows for greatervariability in the proximal branchingpattern of the mca vessels. Note thechoroidal blush along the posteriormargin of the globe (eye)1 internal carotid artery – cervical segment2 internal carotid artery – vertical petrous segment3 internal carotid artery – horizontal petrous segment4 presellar (Fischer C5) segment internal carotid artery6 horizontal (Fischer C4) intracavernoussegment internal carotid artery8 anterior genu (Fischer C3) intracavernous segment ICA10 & 11 proximal and distal supraclinoid segments internal carotid artery

*Arteries to the Parietal & Occipital lobes:-These run posterior to the sylvian fissure , from

superior to inferior :1-Anterior parietal2-Posterior parietal3-Angular4-Occipito-temporal

1-Orbitofrontal , 2-Prefrontal , 3-Precentral , 4-Central , 5-Anterior parietal , 6-Post parietal , 7-Angular , 8-Occipito-temporal , 9-Posterior temporal , 10-Middle temporal , 11-Anterior temporal , 12-Tempero-polar

*Arteries to the Temporal lobe :-These run inferiorly after leaving the lateral

sulcus of the sylvian fissure and are arranged from anterior to posterior :

1-Temporo-polar2-Anterior temporal3-Middle temporal4-Posterior temporal

1-Orbitofrontal 2-Pre-rolandic 3-Rolandic branches 4-Anterior and posterior parietal branches 5-Anterior temporal6-Middle temporal 7-Posterior temporal8-Occipito-temporal

-Anterior temporal branch (best seen in AP view) , a typical appearance of an anterior temporal branch of the MCA proximal to the main bifurcation is indicated with the arrow

Posterior Circulation

Vertebral Artery1-Origin :-They are the first branch of the subclavian

arteries , arise from its superior aspect

2-Course :-Arise from the superior aspect of the subclavian

artery and run vertically and posteriorly to the level of the sixth cervical vertebra (C6) (V1) where they enter the foramen in the transverse process

-The VA then runs superiorly in the vertebral canal passing through foramina in the transverse processes of all the upper cervical vertebrae (V2)

-After leaving the superior border of the foramen of the atlas (C2) , it runs horizontally and posteriorly to pass through the more laterally positioned foramen of the axis (C1) and then turns medially to the foramen magnum (V3)

-There , it penetrates the atlantooccipital membrane and dura to enter the cranial cavity through the foramen magnum and then runs upwards and medially to terminate as the basilar artery , formed by joining its contralateral counterpart anterior to the upper border of the medulla oblongata (V4)

3D volume-rendered (a) and curved reformatted (b) images from contrast-enhanced CT angiography show the segments of the vertebral artery. V1 = between its origin and its entry into the transverse foramen of the C6 vertebra, V2 = midcervical course between the processes of C6 to C2, V3 = atlas loop region, V4 = intracranial segment. Note the asymmetric venous plexus enhancement around the V3 segment (arrow in a)

-Frontal 2D view following right vertebral artery injection , there is a normal appearance of the cervical vertebral artery extending approximately to the vertebral-basilar junction

1 vertebral artery2 muscular branches

3 radiculomedullary feeder to anterior spinal artery4 PICAC1 first cervical vertebraeC2 second cervical vertebrae

-3D frontal view following right vertebral artery injection , there is a normal appearance of the cervical vertebral artery extending approximately to the skull base1 vertebral artery2 muscular branchesC1 first cervical vertebraeC2 second cervical vertebrae

-3D posterior view following right vertebral artery injection , there is a normal appearance of the cervical vertebral artery extending approximately to the skull base1 vertebral artery2 muscular branchesC1 first cervical vertebraeC2 second cervical vertebrae

3-Branches :a) Extracranial Branchesb) Intracranial Branches

a) Extracranial Branches :-In its extracranial course , the VA gives branches which

supply the spinal cord and its dura , cervical vertebrae and muscles as well as the dura of the inferior posterior fossa

-These include (from proximal to distal) :1-Branches to the stellate ganglion2-Spinal branches from C6 to C13-Arteries of the cervical expansion4-Muscular branches5-Anterior meningeal artery

b) Intracranial Branches :-In its intracranial portion , the VA gives branches that

supply dura and the medulla oblongata , upper cervical cord and cerebellum , these are :

1-Posterior meningeal artery and artery of the falx cerebelli

2-Medial Group of Perforator Branches3-Anterior Spinal Artery4-Lateral Spinal Artery5-Posterior Inferior Cerebellar Artery

Anterior spinal artery and artery of the falx cerebelli , a lateral projection of the LT VA shows a well-visualized anterior spinal artery (a.sp.a.) directed inferiorly along the anterior surface of the medulla and spine , the LT PICA has a relatively high origin off the intradural left vertebral artery , the artery of the falx cerebelli (f.cb.) arises from the extracranial vertebral artery , it courses diagonally toward the torcular deviating away from the inner table of the skull

(1) PCA , (2) SCA , (3) Pontine branches of the BA , (4) AICA , (5) Internal auditory artery , (6) VA , (7) PICA , (8) Anterior spinal artery , (9) BA

Basilar Artery1-Origin :-BA is formed by joining of both VAs anterior to

the upper border of the medulla oblongata

-3D frontal view following left vertebral artery injection , shows the intracranial vertebral basilar circulation in a patient with severe atherosclerotic vascular disease , note the moderately severe stenosis of the midbasilar artery in addition to a generalized vessel irregularity1 vertebral artery2 (PICA)3 basilar artery4 (AICA)5 (SCA)5v vermian branch of SCA5h hemispheric branch of SCA6.1 P1 segment of (PCA)6.2 P2 segment of (PCA)8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA

-3D frontal view shows lobulated aneurysm arising from the tip of the basilar artery projecting posteriorly into the interpeduncular cistern 1 vertebral artery2 PICA3 basilar artery4 AICA5 SCA6.1 P1 segment of (PCA)6.2 P2 segment of (PCA)7 PCOM9 parieto-occipital branch of PCA10 calcarine branch of PCA14 vertebral basilar junction

-2D frontal view following vertebral artery injection , shows normal intracranial vertebral basilarcirculation , note the blush (*) of the choroid plexus1 vertebral artery2 posterior inferior cerebellar artery (PICA)2v vermian branch of PICA2h hemispheric branch of PICA3 basilar artery4 anterior inferior cerebellar artery (AICA)5 superior cerebellar artery (SCA)5h hemispheric branch of SCA5v vermian branch of SCA6 posterior cerebral artery (PCA)6.2 P2 segment of PCA8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA12 posterior thalamoperforating arteries13L lateral posterior choroidal artery16 pontine perforating artery* blush of choroids plexus

-3D frontal view following vertebral artery injection , shows normal intracranial vertebral basilarcirculation 1 vertebral artery2 posterior inferior cerebellar artery (PICA)2v vermian branch of PICA2h hemispheric branch of PICA3 basilar artery4 anterior inferior cerebellar artery (AICA)5 superior cerebellar artery (SCA)5h hemispheric branch of SCA5v vermian branch of SCA6 posterior cerebral artery (PCA)6.2 P2 segment of PCA8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA12 posterior thalamoperforating arteries13L lateral posterior choroidal artery16 pontine perforating artery

2-Branches :-Its branches can be divided into two groups ,

the perforating arteries and the long circumferential arteries

a) The Perforating Arteries :-Are paramedian and circumferential in

distribution-They supply the corticospinal tracts , other

connecting white matter tracts and the vital deep nuclei of the pons and midbrain

-In the physiological state , they are rarely visible on angiography and do not cross the midline

-2D frontal view following left vertebral artery injection , the intracranial view ofthe vertebral basilar circulation is of a patient with vasculitis , the vasculitis is illustrated by the multifocal areas of stenosis (narrowing) , the vascular branching pattern shows a typicalappearance of vertebral basilar circulation1 vertebral artery2 (PICA)2v vermian branch of PICA2h hemispheric branch of PICA3 basilar artery4 (AICA)5 (SCA)5v vermian branch of SCA5h hemispheric branch of SCA6.1 P1 segment of (PCA)6.2 P2 segment of (PCA)7 PCOM8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA11 anterior thalamoperforating arteries12 posterior thalamoperforating arteries13m medial posterior choroidal artery13L lateral posterior choroidal artery14 vertebral basilar junction15 splenial branch (posterior pericallosal artery) of PCA** region of quadrigeminal plate cistern17 anterior spinal artery

-2D lateral early arteiral view following left vertebral artery injection , the intracranial view of the vertebral basilar circulation is of a patient with vasculitis , the vasculitis is illustrated by the multifocal areas of stenosis (narrowing) , the vascular branching pattern shows a typicalappearance of vertebral basilar circulation1 vertebral artery2 (PICA)2v vermian branch of PICA2h hemispheric branch of PICA3 basilar artery4 (AICA)5 (SCA)5v vermian branch of SCA5h hemispheric branch of SCA6.1 P1 segment of (PCA)6.2 P2 segment of (PCA)7 PCOM8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA11 anterior thalamoperforating arteries12 posterior thalamoperforating arteries13m medial posterior choroidal artery13L lateral posterior choroidal artery14 vertebral basilar junction15 splenial branch (posterior pericallosal artery) of PCA** region of quadrigeminal plate cistern17 anterior spinal artery

-2D lateral late arterial phase view following left vertebral artery injection , the intracranial view of the vertebral basilar circulation is of a patient with vasculitis , the vasculitis is illustrated by the multifocal areas of stenosis (narrowing) , the vascular branching pattern shows a typicalappearance of vertebral basilar circulation1 vertebral artery2 (PICA)2v vermian branch of PICA2h hemispheric branch of PICA3 basilar artery4 (AICA)5 (SCA)5v vermian branch of SCA5h hemispheric branch of SCA6.1 P1 segment of (PCA)6.2 P2 segment of (PCA)7 PCOM8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA11 anterior thalamoperforating arteries12 posterior thalamoperforating arteries13m medial posterior choroidal artery13L lateral posterior choroidal artery14 vertebral basilar junction15 splenial branch (posterior pericallosal artery) of PCA** region of quadrigeminal plate cistern17 anterior spinal artery

b) The Long Circumferential Arteries :1-Internal Auditory Artery (Labyrinthine Artery)2-The Anterior Inferior Cerebellar Artery (AICA)3-The Superior Cerebellar Artery (SCA)4-Posterior Cerebral Artery (PCA)

-2D frontal view following vertebral artery injection , shows normal intracranial vertebral basilarcirculation , note the blush (*) of the choroid plexus1 vertebral artery2 posterior inferior cerebellar artery (PICA)2v vermian branch of PICA2h hemispheric branch of PICA3 basilar artery4 anterior inferior cerebellar artery (AICA)5 superior cerebellar artery (SCA)5h hemispheric branch of SCA5v vermian branch of SCA6 posterior cerebral artery (PCA)6.2 P2 segment of PCA8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA12 posterior thalamoperforating arteries13L lateral posterior choroidal artery16 pontine perforating artery* blush of choroids plexus

-3D frontal ) view following leftvertebral artery injection , this view show intracranial vertebral basilar circulation in a patient with severe atherosclerotic vascular disease , note the multifocal areas of vessel irregularity and narrowing (stenoses) and the severe narrowing of the distal right vertebral artery (*) , this is a good demonstration of a right AICA-PICA where a medial branch of AICA supplies all or a portion of the PICA territory1 vertebral artery2 (PICA)3 basilar artery4 (AICA)4 – PICA AICA-PICA5 (SCA)5h hemispheric branch of SCA5v vermian branch of SCA6.1 P1 segment of (PCA)6.2 P2 segment of (PCA)8 posterior temporal branch of PCA* severe stenosis (narrowing) distal rightvertebral artery

-2D lateral view following vertebral artery injection , intracranial vertebral basilar circulation is seen with a moderate-size aneurysm arising from the distal vertebral artery near the origin of the PICAvertebral artery2 (PICA)2v vermian branch of PICA2h hemispheric branch of PICA3 basilar artery4 (AICA)5 (SCA)5h hemispheric branch of SCA6 (PCA)6.1 P1 segment of PCA6.2 P2 segment of PCA8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA12 posterior thalamoperforating arteries13m medial posterior choroidal arteries13L lateral posterior choroidal arteries15 splenial branch (posterior pericallosal artery) branch of PCA

-3D frontal view following right vertebral artery injection , this view shows normal intracranial vertebral basilar circulation , note the duplication of the right SCA , this is a normal variant1 vertebral artery2 (PICA)3 basilar artery4 (AICA)5 (SCA)5h hemispheric branch of SCA5v vermian branch of SCA6 (PCA)6.1 P1 segment of PCA6.2 P2 segment of PCA8 posterior temporal branch of PCA9 parieto-occipital branch of PCA10 calcarine branch of PCA14 vertebral basilar junction

External Carotid Artery

a) Origin :-Bifurcation of the common carotid artery

b) Supply :-The ECA supplies the tissues of the scalp , face

and neck

-Lateral 2D view followingselective external carotid artery injection , there is a hypervascular mass adjacent to the proximal ECA, this is the typical appearance of a carotid body tumor (glomus or paraganglioma)6 occipital artery9 lingual artery10 facial artery11 superficial temporal artery12 internal maxillary artery13 middle meningeal artery15 deep temporal artery

-Lateral 3D view following left common carotid artery injection , note the hypervascular mass typical of a carotid body tumor (glomus or paraganglioma) situated between the proximal internal and external carotid arteries1 common carotid artery2 internal carotid artery3 external carotid artery4 ascending pharyngeal artery7 superior thyroid artery9 lingual artery10 facial artery

c) Course :-It arises at the level of the superior border of the

thyroid cartilage and terminates beneath the neck of the mandible by dividing into superficial temporal and internal maxillary arteries

-At its origin , it is situated Anterior to the ICA but as it ascends , it lies more Posteriorly and finally Lateral to ICA (APL)

-Thus , on frontal angiography its origin is medial to the ICA origin and the vessels reverse their relative positions as they run superiorly but on the lateral view the ICA is always posterior

AP (2=ICA,3=ECA) Lateral (2=ICA,3=ECA)

d) Branches :-It has eight branches which will be described in their

usual sequence from proximal to distal-These are :1-Superior Thyroid artery2-Lingual artery3-Ascending Pharyngeal artery (APA)4-Facial artery (FA)5-Occipital artery (OA)6-Posterior Auricular artery (PA)7-Superficial Temporal artery (STA) (terminal)8-Internal Maxillary artery (IMA) (terminal)

Black key1 ascending thoracic aorta2 descending thoracic aorta3 innominate artery4 right subclavian artery5 stump of right common carotid artery6 right vertebral artery7 right thyrocervical trunk8 right costocervical trunk9 right internal mammary artery10 left subclavian artery11 left vertebral artery12 left thyrocervical trunk13 left costocervical trunk14 left internal mammary artery15 left common carotid artery

Red key

2 internal carotid artery3 external carotid artery4 ascending pharyngeal 5 occipital artery6 posterior auricular artery7 superior thyroid artery9 lingual artery10 facial artery11 superficial temporal 12 internal maxillary artery24 transverse facial artery

-Frontal left common carotid artery injection , normal 2D appearance of the left common carotid artery bifurcation region1 common carotid artery2 internal carotid artery2b carotid bulb3 external carotid artery4 ascending pharyngeal5 occipital artery6 posterior auricular artery7 superior thyroid artery9 lingual artery10 facial artery11 superficial temporal12 internal maxillary artery

-Lateral left common carotid artery injection , normal 2D appearance of the left common carotid artery bifurcation region1 common carotid artery2 internal carotid artery2b carotid bulb3 external carotid artery4 ascending pharyngeal5 occipital artery6 posterior auricular artery7 superior thyroid artery9 lingual artery10 facial artery11 superficial temporal12 internal maxillary artery

-Frontal following left common carotid artery injection , there is a normal 3D appearance of the left common carotid artery bifurcation region1 common carotid artery2 internal carotid artery2b carotid bulb3 external carotid artery5 occipital artery6 posterior auricular artery7 superior thyroid artery9 lingual artery10 facial artery

-lateral following left common carotid artery injection , there is a normal 3D appearance of the left common carotid artery bifurcation region1 common carotid artery2 internal carotid artery2b carotid bulb3 external carotid artery5 occipital artery6 posterior auricular artery7 superior thyroid artery9 lingual artery10 facial artery

-Posterior following left common carotid artery injection , there is a normal 3D appearance of the left common carotid artery bifurcation region1 common carotid artery2 internal carotid artery2b carotid bulb3 external carotid artery5 occipital artery6 posterior auricular artery7 superior thyroid artery9 lingual artery10 facial artery

-Right anterior oblique view following left common carotid artery injection , there is a normal 3D appearance of the left common carotid artery bifurcation region1 common carotid artery2 internal carotid artery2b carotid bulb3 external carotid artery5 occipital artery6 posterior auricular artery7 superior thyroid artery9 lingual artery10 facial artery

1-Common Carotid Artery2-Internal Carotid Artery3-Ascending pharyngeal Artery4-Occipital Artery5-Superficial Temporal Artery6-Middle cerebral Artery7-Anterior cerebral Artery8-Middle meningeal Artery9-Maxillary artery10-Facial artery11-Lingual artery12-External carotid artery13-Superior thyroid artery

Venous Drainage

Intracranial VeinsThere are five types of intracranial veins :1-Diploic Veins2-Emissary Veins3-Meningeal Veins4-Dural Venous Sinuses 5-Cerebral Veins

1-Diploic Veins :-These are relatively large thin-walled

endothelial lined channels which run between the inner and outer table of the skull , i.e. in the diploe

-Communicate with the overlying scalp veins and with the underlying meningeal veins and dural sinuses

2-Emissary Veins :-These are connecting veins between

extracranial veins , diploic veins and the intracranial meningeal veins and sinuses

-They are concentrated around the major dural sinuses , particularly parasagittal to the superior sagittal sinus and around the sigmoid sinus

3-Meningeal Veins :-The meningeal veins form a plexus in the outer

layer of dura and between it and the periosteum of the inner table of the skull

4-Dural Venous Sinuses :-Sinuses are formed within two layers of dura

and drain the veins of the brain , the meninges and the cranium principally into the internal jugular vein

-They comprise the following :1-Superior Sagittal Sinus2-Inferior Sagittal Sinus3-Straight Sinus4-Transverse Sinus5-Superior Petrosal Sinus6-Sigmoid Sinus7-Occipital Sinus and Marginal Sinuses8-Inferior Petrosal Sinus9-Sphenoparietal Sinus10-Cavernous Sinuses

T1+C shows a large CSF-isointense filling defect , consistent with an arachnoid granulation (black arrows) , at the junction point of the vein of Galen and straight sinus , note also the presence of smaller arachnoid granulations within the superior sagittal sinus (white arrowheads)

Technique

Aneurysm

Endovascular Treatments of Intracranial Aneurysms

1-Aim of Treatment2-Parent Artery Occlusion3-Endosaccular Embolization4-Adjuvant Endovascular Treatments

1-Aim of Treatment :-The reason to treat is the risk of rebleeding and the aim

is to exclude the aneurysm from the arterial circulation without compromising any perfusion territory

-Endovascular treatments to occlude aneurysms can be divided into those than involve occlusion of the parent artery and those that preserve it , we are rapidly progressing to the point when the former is largely obsolete , but it is likely to retain a limited role for some time yet

2-Parent Artery Occlusion :a) Techniqueb) Indicationsc) Complications

a) Technique :-Occlusion of the aneurysm parent artery is an

effective method of inducing thrombosis and preventing aneurysm growth and rupture

-Endovascular arterial occlusion has replaced surgical ligation because prior temporary balloon occlusion allows assessment of collateral blood flow and is safer

-Occlusion is generally performed at the level of the aneurysm neck or immediately proximal to the neck

b) Indications :1-Giant secular aneurysms with wide necks and

heavily calcified walls2-Wide-necked & fusiform aneurysms3-Distal aneurysms above the level of the circle

of Willis on small arteries4-Posttraumatic pseudoaneurysms & infectious

aneurysms5-Failed endosaccular embolization

c) Complications :-Complications are :1-Transient neurological deficit (7.25-10.3 %)2-Permanent deficits (1.5-4.4 %)

3-Endosaccular Embolization :a) Techniqueb) Complications

a) Technique :-Coil embolization is performed under general

anaesthesia so the patients can be adequately monitored and immobilized

-Selective catheterization of the aneurysm sac is performed after systemic anticoagulation (by bolus injection or infusion of heparin) and packing is usually performed by placing large initial coils into which smaller coils are packed

b) Complications :1-Periprocedural Complications2-Delayed Complications

1-Periprocedural Complications :a) Aneurysm Ruptureb) Thromboembolic Events

2-Delayed Complications :a) Aneurysm Rebleedingb) Rupture of Previously Unruptured Aneurysmsc) Exacerbation of compression syndromesd) Hydrocephaluse) Sterile meningitic reaction adjacent to the thrombosed

aneurysmf) Transient ischemic episodesg) Radiation induced alopeciah) Seizuresi) Coil compaction causing aneurysms recurrence

5-Adjuvant Endovascular Treatments :-Coil embolization for a minority of aneurysms isn’t

possible because of their anatomy-The features that make a particular aneurysm

uncoilable are :a) Wide neckb) Extreme sizec) Branch arteries arising from within the sacd) Fusiform shape-Stent & Coils and Flow Diverters

a) Stent & Coil :-Placing a stent in the parent artery is a logical solution

to the problem of retaining coils in sessile very wide-necked aneurysms

-Initially , the combined use of coils and stents was confined to treatments of unruptured aneurysms because of the need to place patients on antiplatelet drugs (in addition to periprocedural heparin) as prophylaxis against thrombosis within the stent

b) Balloon-Assisted Coiling :-Balloon-assisted coiling (BAC) which is also known

as (the remodelling technique) involves placement of a suitably sized compliant balloon across the aneurysm neck during coil deployment , the balloon is used to retain coils within the aneurysm to compress their profile at the neck (i.e. remodelling) and to be available to arrest blood flow should rupture occur during embolization

c) Flow Diverters :-Flow diverters have been developed to treat

intracranial aneurysms-These endovascular devices are placed within

the parent artery rather than the aneurysm sac

-They take advantage of altering hemodynamics at the aneurysm / parent vessel interface resulting in gradual thrombosis of the aneurysm occurring over time

Arterio-Venous Malformation (AVM)

Treatment of Brain AVM-The principle aim of treatment is to eliminate the

lifelong risk of hemorrhage-The assumption underlying any form of intervention is

that complete obliteration / removal of the BAVM means that the patient is no longer at risk of future hemorrhage

-Incomplete treatment risks recurrence and future bleeding

-The effects of anatomical cure on other symptoms are less certain

1-Medical Management2-Surgical Resection3-Radiotherapy4-Embolisation

Embolisation-Embolisation is used alone or as an adjuvant

treatment combined with surgery or radiotherapy

-The goals of treatment are different if it is attempted for complete cure , to facilitate surgery or radiotherapy or used as palliative treatment

-We use :1-Cyanoacrylate agents , i.e. N-butyl-2-

cyanoacrylate (n-BCA)2-Onyx

Stroke

Treatment of Acute Stroke1-Intravenous Thrombolysis for Acute Stroke2-Intra-arterial Thrombolysis for Acute Stroke3-Combined Intravenous and Intra-arterial

Thrombolysis4-Stent Retrieval Devices

1-Intravenous Thrombolysis for Acute Stroke :-More recent trials of intravenous (IV)

thrombolysis have used rtPA-They suggest that the treatment is effective if

instigated in the first few hours after the stroke

2-Intra-arterial Thrombolysis for Acute Stroke :-The rationale of intra-arterial (IA) thrombolysis

is to target the drug to the site of thrombosis-Its goal is the same as intravenous treatment ,

i.e. to limit the area of infarcted parenchyma and to enhance the survival of any functionally disabled cerebral tissue in the surrounding ischaemic penumbra

3-Combined Intravenous and Intra-arterial Thrombolysis :

-Combination treatment or ‘bridging’ therapy in which IV rtPA is given during investigations and triage for possible IA treatment , is widely practised

4-Stent Retrieval Devices :-The technique involves passing a microcatheter (over a

standard guidewire) through the thrombus and then delivering the retrievable stent device across the occluded segment

-The stent device is deployed by retrieving the microcatheter, and then a period of 3-5 min should be allowed for the clot to become entrapped within the frame of the device

-The device (and contained thrombus) is then retrieved during the arrest of blood flow in the proximal artery