Circle of willis 360°

transcript

Circle of Willis 360°24-4-20162.54 am

Great teachers – All this is their work . I am just the reader of their books .

Prof. Paolo castelnuovo

Prof. Aldo Stamm Prof. Mario Sanna

Prof. Magnan

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Circle of willis in anterior & lateral skull base view

??? is intracerebral carotid

ICA Vertebro-basillar

In anterior skull base approach

Middle cranial fossa approach

In anterior skull base approach - Type C Modified Transcochlear Approach – after cutting the tentorium

With mild retraction of the temporal lobe, the bifurcation of the internal carotid artery (ICA) into the anterior (ACA) and middle cerebral (MCA) arteries is seen. The ipsilateral (ON) and contralateral (ONc) optic nerves are seen. The oculomotor nerve (III) is embraced by the posterior cerebral artery (PCA) superiorly and the superior cerebellar artery (SCA) inferiorly

http://www.ajnr.org/content/27/8/1770/F2.expansion.htmlClassification of the anatomic variations in the circle of Willis. In the “textbook” type, both the

precommunicating segment of the anterior cerebral artery (A1) and that of the posterior cerebral artery (P1) were normal in size. The next group included both right and left A1 hypoplasia.

Because no significant difference between cerebral arteries on the right and left sides has been established,5,18 we combined right and left A1 hypoplasia into A1 hypoplasia. The next group

included right and left P1 hypoplasia, which again were treated as a single category, P1 hypoplasia. “Other” type included a combination of A1 hypoplasia and P1 hypoplasia, bilateral P1

hypoplasia, as well as other unclassified variations. ACA indicates anterior cerebral artery; ACo, anterior communicating artery; MCA, middle cerebral artery; ICA, internal cerebral artery; PCo,

posterior communicating artery; PCA, posterior cerebral artery; BA, basilar artery

http://www.ajnr.org/content/27/8/1770/F3.expansion.htmlRelative contribution of proximal arteries to total volume flow in variations in the circle of Willis.

Values signify mean percentage ± SD. The upper left value corresponds to the relative contribution of the right internal carotid artery in the “textbook” type or of the internal carotid

artery ipsilateral to hypoplastic A1 or P1 in the other variations. The upper right value corresponds to the relative contribution of the left internal carotid artery in the “textbook” type, or of the internal carotid artery contralateral to hypoplastic A1 or P1 in the other variations. The

value at the bottom corresponds to the relative contribution of the basilar artery.* The value for A1 hypoplasia variation was significantly smaller than those for “textbook” type and P1 hypoplasia variation. The value for P1 hypoplasia variation was significantly larger than

that for “textbook” type.** The value for A1 hypoplasia variation was significantly larger than that for “textbook” type.

*** The value for P1 hypoplasia variation was significantly smaller than that for “textbook” type.

http://stroke.ahajournals.org/content/30/12/2671/F2.expansion.htmlScheme of anatomic variations of the posterior part of the CW: variant types a

through c are complete, whereas the remainder are incomplete. a, Bilateral PCoApresent. b, PCA originating predominantly from the ICA. This type is known as a

unilateral fetal-type PCA (FTP), indicated by the arrows; the PCoA on the other side is present. c, Bilateral FTP, with both P1 segments patent. d, Unilateral PCoA present. e,

Hypoplasia or absence of both PCoAs, with isolation of the anterior and posterior circle parts at this level. f, Unilateral FTP, with hypoplasia or absence of the P1

segment. g, Unilateral FTP, with hypoplasia or absence of the contralateral PCoA. h, Unilateral FTP, with hypoplasia or absence of the P1 and PCoA. i, Bilateral FTP, with

hypoplasia or absence of both P1 segments. j, Bilateral FTP, with hypoplasia or absence of one P1 segment.

Pcom absent in post-craniopharyngioma case

http://www.anatomyatlases.org/AnatomicVariants/Cardiova

scular/Images0200/0294B.gif

Cisternal / Intracranial ICA [ICA i]

Anatomically speaking, the paraclinoid segment of the internal carotid artery is not fully intracavernous, and it is separated from the cavernous sinus by the extension of the dura

covering the inferior surface of the anterior clinoid process (Reisch et al. 2002 ) .

Note carotid cave , cavernous sinus , upper & lower dural rings

Oculomotor cistern Cranial nerve III enters the roof included in its own cistern

(oculomotor cistern).

Oculomotor cistern goes uptoanterior clinoid tip

The mOCR is located just medial to the paraclinoidal-supraclinoidal ICA transition and inferior to the distal cisternal segment of the ON(Labib et al. 2013 ).

Cl clivus, ICAc cavernous portion of the internal carotid artery, ON optic nerve, PG pituitarygland, PS planum sphenoidale, TS tuberculum sellae, yellow asterisks upper dural ring, bluearrowheads lower dural ring, white asterisk lateral optico-carotid recess, white circle medial

optico-carotid recess, white arrow ophthalmic artery, black arrows middle clinoid process, redarrows lateral tubercular crest, yellow arrows endocranial region corresponding to MCP

Cadaveric dissection image demonstrating the close anatomical relationship of the posterior clinoid (PC) with both the intracranial carotid artery (ICCA)

and the posterior genu of the intracavernous carotid artery (P. CCA). AL, anterior lobe of the pituitary gland; PL, posterior lobe of the pituitary gland;

BA, basilar artery.

green dotted triangle area for entry of the endoscope into the interpeduncular fossa

Posterior clinoidectomy in cisternostomy in head injury video –

by Dr. Iype Cherian - click https://www.youtube.com/watch?v

=vNaEFMrdgfw

Aneurysms of initial intracranial carotid

Opthalmic artery – Retrograde branch of Intracranial carotid

Branches of the cavernous internalcarotid artery ( ICA ), a rare variation: ophthalmicartery passing through the superiororbital fissure

In the lateral border of the chiasmatic cistern the first part ofthe ICAi is visible.

Note Optic tract here which is above Posterior clinoid process [ PCP ]

In the lateral border of the chiasmatic cistern the first part ofthe ICAi is visible.

Dry bone dissection image taken with a 30-degree endoscope demonstrating the fovea ethmoidalis (FE) and cribriform plate (CP) junction with the planum sphenoidale (PS). This is marked approximately by the posterior ethmoidale artery (PEA). ISS, intersinus septum of sphenoid sinus; ON, optic nerve; CCA, anterior genu of the intracavernous carotid artery.

Supra-clinoidal carotid=1st part of intracranial carotid

APAs anterior perforating arteries, ICAi intracranial portion ofthe internal carotid artery, OT optic tract, SF Sylvian fi ssure,

A 1 [ ACA ] crosses above the Optic tract , not Optic nerve .

Left subchiasmatic cistern

ACA anterior cerebral artery, APAs anterior perforating arteries, FOA fronto-orbital artery,FOV fronto-orbital vein, FPA fronto-polar artery, ICAi intracranial segment of the internal

carotid artery, MCA middle cerebral artery, OlfT olfactory tract, OlfV olfactory vein, ON opticnerve, PS pituitary stalk, TL temporal lobe, black asterisk anterior communicating artery

ICA dividing into ACA and MCA

Optic tract [ OT ]

Sub frontal approach

Fig. 2.1 Drawing showing the skin incision (red line), the craniotomyand the microsurgical intraoperative view of the subfrontal unilateral approach. This approach provides a wide intracranial exposure of the frontal lobe and easy access to the optic nerves, the chiasm, the carotid

arteries and the anterior communicating complex

Fig. 2.4 Intraoperative microsurgical photograph showing contralateralextension of the tumor (T) dissected via a unilateral subfrontal

approach. Note on the left side the falx cerebri (F) andthe mesial surface of the left frontal lobe (FL)

Fig. 2.5 Drawing showing the skin incision (red line), the craniotomyand the microsurgical anatomic view of the subfrontal bilateral

route. This approach provides a wide symmetrical anteriorcranial fossa exposure and easy access to the optic nerves, the

chiasm, the carotid arteries and the anterior communicating arteriescomplex

Supraorbital approach - Fig. 3.2 Illustrations comparing the incision and

bony exposure in a supraorbital craniotomy with those in a pterional craniotomy. a The supraorbital craniotomy utilizes the subfrontal corridor and involves a frontobasal

burr hole and removal of a small window in the frontal bone. b The pterionalcraniotomy utilizes a frontotemporal incision and removal of the frontal and temporal

bones andsphenoid wing. The pterional craniotomy primarily exploits the sylvianfissure

Frontotemporal approach

Fig. 4.6 a Craniotomy. b When the flap has been removed thelesser wing of the sphenoid is drilled down to optimize the most

basal trajectory to the skull base. c Dural opening. DM duramater, FL frontal lobe, MMA middle meningeal artery, LWSB

lesser wing of the sphenoid bone, SF sylvian fissure, TL temporallobe, TM temporal muscle, ZPFB zygomatic process of the frontal bone

Fig. 4.8 Intradural exposure; right approach. Before (a) and after (b) opening of the Sylvian fissure. A1 first segment of the anterior cerebral artery, AC anterior clinoid, FL

frontal lobe, HA Heubner’s artery, I olfactory tract, III oculomotor nerve, ICA internal carotid artery, LT lamina terminalis, M1 first segment of the middle cerebral artery,

MPAs perforating arteries, ON optic nerve, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PcoA posterior communicating artery, SF sylvian

fissure, TL temporal lobe, TS tuberculum sellae

Fig. 4.9 Intradural exposure; right approach. a Instruments enlarging the optocarotidarea. b Displacing medially the posterior communicating artery, exposing the

contents of the interpeduncular cistern. AC anterior clinoid, AchA anterior choroidalartery, BA basilar artery, FL frontal lobe, ICA internal carotid artery, III oculomotor

nerve, OA left ophthalmic artery, ON optic nerve, OT optic tract, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PcoA posterior communicating

artery, Ps pituitary stalk, SCA superior cerebellar artery, SHA superior hypophysealartery, TE tentorial edge, TL temporal lobe

Fig. 4.10 Intradural exposure; right approach; enlarged view. A1 first segment of the anterior cerebral artery, A2 second segment of the anterior cerebral artery, AC anterior clinoid, AcoAanterior communicating artery, BA basilar artery, FL frontal lobe, HA Heubner’s artery, ICA

internal carotid artery, III oculomotor nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic artery, ON optic nerve, P2 second segment of the posterior

cerebral artery, PC posterior clinoid, PcoA posterior communicating artery, SCA superior cerebellarartery, SHA superior hypophyseal artery, TE tentorial edge, TL temporal lobe, TS tuberculum sellae

Posteior clinoid can be approached in optico-carotid triangle [ 3mm ] OR lateral carotid triangle

Pcom is seen in optico-carotid triangle – can be injured in cisternostomy while cutting lillequet membrane

Fig. 4.11 Intradural exposure; right approach; close-up view ofthe interpeduncular fossa. AchA anterior choroidal artery, BAbasilar artery, DS dorsum sellae, III oculomotor nerve, IV

trochlear nerve, P1 first segment of the posterior cerebral artery,P2 second segment of the posterior cerebral artery, PC posteriorclinoid, PcoA posterior communicating artery, Ps pituitary

stalk, SCA superior cerebellar artery, TE tentorial edge

Endoscope-assisted microsurgery [ 45° endoscope in a corridor between the carotid artery and the oculomotor nerve ]-- Fig. 4.12

Intradural exposure; right approach; microsurgical (a) and endoscopic (b–d) views. AchAanterior choroidal artery, BA basilar artery, C clivus, FL frontal lobe, ICA internal carotid artery, III

oculomotor nerve, ON optic nerve, P1 first segment of the posterior cerebral artery, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PCA posterior cerebral artery, PcoA

posterior communicating artery, SCA superior cerebellar artery, TE tentorial edge, TL temporal

lobe, Tu thalamoperforating artery; green dotted triangle area for entry of

the endoscope into the interpeduncular fossa

Cadaveric dissection image demonstrating the close anatomical relationship of the posterior clinoid (PC) with both the intracranial carotid artery (ICCA)

and the posterior genu of the intracavernous carotid artery (P. CCA). AL, anterior lobe of the pituitary gland; PL, posterior lobe of the pituitary gland;

BA, basilar artery.

green dotted triangle area for entry of the endoscope into the interpeduncular fossa

Fig. 4.12 Intradural exposure; right approach; microsurgical (a) and endoscopic (b–d) views. AchA anterior choroidal artery, BA basilar artery, C clivus, FL frontal lobe, ICA internal carotid

artery, III oculomotor nerve, ON optic nerve, P1 first segment of the posterior cerebral artery, P2 second segment of the posterior cerebral artery, PC posterior clinoid, PCA posterior cerebral

artery, PcoA posterior communicating artery, SCA superior cerebellar artery, TE tentorial edge, TL temporal lobe, Tu thalamoperforating artery; green dotted triangle area for entry of the

endoscope into the interpeduncular fossa

Fig. 4.13 Intradural exposure; right approach; microsurgical (a)and endoscopic omolateral (b) and contralateral (c) views. A1 first segment of the anterior cerebral artery, AC anterior clinoid, ICA internal carotid artery, FL frontal lobe, III oculomotor

nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic artery, ON optic nerve, PcoA posterior communicating artery, SHA superior hypophyseal artery, TE

tentorial edge, TS tuberculum sellae

Fig. 4.13 Intradural exposure; right approach; microsurgical (a)and endoscopic omolateral (b) and contralateral (c) views. A1 first segment of the anterior cerebral artery, AC anterior clinoid, ICA internal carotid artery, FL frontal lobe, III oculomotor

nerve, LT lamina terminalis, M1 first segment of the middle cerebral artery, OA left ophthalmic artery, ON optic nerve, PcoA posterior communicating artery, SHA superior hypophyseal artery, TE

tentorial edge, TS tuberculum sellae

Craniopharyngioma

https://www.facebook.com/groups/405175366256295/permalink/552393

251534505/?stream_ref=2

Pterional

CRANIOPHARYNGIOMAS-Removal corridors.

Cyst of craniopharyngioma

https://www.scienceopen.com/document_file/84699ab2-4980-4f70-a5b0-c8d95a1fb6a2/PubMedCentral/84699ab2-4980-4f70-a5b0-c8d95a1fb6a2.pdf

FIGURE 4. The capsule of the cystic craniopharyngioma was firmly attached to the left hypothalamus, the stalk was dislocated to the right side (Patient 6). The outgrowth of the

craniopharyngioma from proximal stalk is recognizable A. Complete removal of the capsule was possible, but produced subpial blood injection over the left hypothalamic surface B. MRI scan revealed a small ischemic injury in the left hypothalamus C. This patient had transient sleep

disorder, moderate hyperphagia and memory problems (see also a supplemented video material 1).

FIGURE 2. In this cystic craniopharyngioma (Patient 5), the stalk was centrally infiltrated close to the pituitary and could not be preserved A. The incipient third

ventricle entrance is seen from intracavitary view. The slit into the third ventricle is still covered with tumour capsule B. Complete removal of the capsule opened the

third ventricle C. Petehiae in the hypothalamus bilaterally resulted from apparently gentle traction and blunt dissection of the capsule away from the hypothalamus

D. Psychoorganic change, disorientation and memory deficits were noticed in less than a week after surgery, the transient sleep disorder become apparent in the

second week postoperatively (see also a supplemented video material 2).

FIGURE 3. Large craniopharyngioma (Patient 3) produced unilateral hydrocephalus by obstructing the right formen of Monro A. The dome was filled with soft

cholesterine cristals B, which were easily removed. Lower limbus of the right foramen of Monro is seen through the empty third ventricle D. Despite bilateral preservation

of anteromedial hypothalamus C and stalk preservation E, the patient developed panhypopituitarism and diabetes insipidus with long lasting psychoorganic change

Fronto-temporal orbitozygomatictranscavernous approach

COM= Caratico-occulomotormembrane , DR = dural ring

Division of PComA

Fig. 4.15 Microsurgical view; extradural anterior clinoidectomy. a Exposure and drilling of the anterior clinoid process

and optic canal under microscope magnification. b Widened space after complete removal of the AC. AC anterior clinoid, eON extracranial intracanalar optic nerve, FD frontal dura, ICA

internal carotid artery, iON intraorbital optic nerve, LWSB lesser wing of sphenoid bone, OC optic canal, OR orbit roof, SOF superior orbital fissure, TD temporal dura

Fig. 4.16 Microsurgical view; intradural anterior clinoidectomy. a, b After the dura above the anterior clinoid process has been transected in a “T” shape (a), we usually drill always parallel

tothe optic nerve and to the carotid artery (b). c The distal ring is finally exposed. A1 precommunicating anterior cerebral artery, AC anterior clinoid, AchA anterior choroid artery, Ch optic chiasm, DR distal ring, fl falciform ligament, FL frontal lobe, ICA internal carotid artery, M1

first tract of the middle cerebral artery, ON optic nerve, PC posterior clinoid, PCOA posterior communicating artery, TS tuberculum sellae

Fig. 4.16 Microsurgical view; intradural anterior clinoidectomy. a, b After the dura above the anterior clinoid process has been transected in a “T” shape (a), we usually drill always parallel

tothe optic nerve and to the carotid artery (b). c The distal ring is finally exposed. A1 precommunicating anterior cerebral artery, AC anterior clinoid, AchA anterior choroid artery, Ch optic chiasm, DR distal ring, fl falciform ligament, FL frontal lobe, ICA internal carotid artery, M1

first tract of the middle cerebral artery, ON optic nerve, PC posterior clinoid, PCOA posterior communicating artery, TS tuberculum sellae

Posterior clinoidectomy

FTOZ – Fronto-temporal orbitozygomatic approach

Subtemporal approach

Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisura

obtained through the pretemporal and subtemporal corridors. In this patient thebasilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c Intraoperative photograph of another patient showing structures in the left lateral incisural space from the

subtemporal corridor. d Same patient. More lateral view. e Same patient. More posterior exposure. The lifting of the free edge of the tentorium shows the trochlear nerve entering the tentorium. The junction between the P2a and P2p segments (P2a, P2p) of the posterior cerebral artery is shown. ACA anterior cerebral artery, AChA

anterior choroidal artery and tiny perforating vessels, BA basilar artery, DS dorsum sellae, FET free edge of tentorium, ICA internal carotid artery, LM Liliequist’s membrane, LON left optic nerve, ON oculomotor nerve, OT

optic tract, PCA posterior cerebral artery, PComA posterior communicating artery, PLChA posterolateralchoroidal artery arising from the P2a–P2p junction, PS pituitary stalk, RON right optic nerve, SCA superior

cerebellar artery, TN trochlear nerve in the arachnoidal covering

Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisuraobtained through the pretemporal and subtemporal corridors. In this patient the

basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c Intraoperative photograph of another patient showing structures in the left lateral incisural space from the

Fig. 7.13 a Intraoperative photograph shows good exposure of the left tentorial anterior and middle incisuraobtained through the pretemporal and subtemporal corridors. In this patient the

basilar apex is well above the superior margin of the dorsum sellae. b Same patient. A more lateral exposure showing the pontomesencephalic junction surface and the neurovascular structures in the ambient cistern. c Intraoperative photograph of another patient showing structures in the left lateral incisural space from the

THE FULLY ENDOSCOPIC SUBTEMPORAL APPROACH [ from Shahanian book ] - The traditional middle fossa subtemporal approach requires long-

standing placement of retractors on the temporal lobe; therefore, potential injury to the temporal lobe can occur

(e.g., hematoma and edema resulting in aphasia, hemiparesis, or seizures). This concern should not be a problem with the described approach because temporal lobe retractors are not used.

(L) a Epidermoid tumor. b Atraumaticsuction. c Brainstem. d Occulomotor (III) nerve. e Posterior cerebral artery (PCA).f Superior cerebellar artery (SCA). g Trochlear (IV) nerve.

(N) a Epidermoid tumor. b Atraumatic suction. c Left-curved tumor forceps. d Occulomotor (III) nerve. e Posterior cerebral artery (PCA). f Posterior communicating (PCOM) artery. g Superior cerebellar artery (SCA).h Brainstem. i Trochlear (IV) nerve.

Q) a Occulomotor (III) nerve. b Internal carotid artery (ICA). c Posterior cerebral artery (PCA).d Superior cerebellar artery (SCA).

(P) a Ipsilateral optic (II) nerve. b Internal carotid artery (ICA). c Occulomotor (III) nerve.d Dura overlying anterior clinoidprocess.

The recurrent artery of Heubner usually origins from the post-communicating segment of the anteriorcerebral artery (ACA). It doubles back the ACA to reach the medial part of the Sylvian fi ssure, below

the anterior perforated substance. Sometimes its path is so long that the artery loops below the basalsurface of the frontal lobes. Not frequently more than one recurrent arteries can be present (Rhoton

2003 ). According to Lang the artery is double in about 30% of cases (Lang 1995 ) .

3rd ventricle entry by - Supra optic chiasmic route – by Lamina terminalis

Recurrent artery of heubner originates near Acom

(A) The middle cerebral artery (MCA) gives rise to the lateral lenticulostriate arteries (LLA) at the bifurcation complex. The medial lenticulostriate arteries (MLA) arise from the proximal section of A1. At the juncture of A1-AComm-A2 the recurrent artery of Heubner (RAH) is given off. AComm completes the anterior portion of the circle of

Willis and has several perforating vessels ( Acomm Perf) that head posteriorly. In the first 5 mm of A2 the orbitofrontal ( OF) artery is given off with the frontopolar (FP)

artery staying more medial. (B) A clinical picture after removal of a tuberculum sellameningioma with a well-defined display of the anterior cerebral arteries.

Recurrent artery of heubner [ R-RAH ] originates near Acom

In parasellar pituitary 3rd n & 4th n & Pcom present in Postero-superior cavernous compartment

a,b Intraoperative image of the fenestration of deep cystic membrane using different microsurgical instruments (forceps and scissors). Asterisks posterior communicating artery and anterior choroidal

artery. c Fenestration of the cisternal layer (cross Liliequist’s membrane). d Intraoperative picture at the end of the procedure

http://www.springerimages.com/Images/MedicineAndPublicHealth/1-10.1007_s00381-004-0940-4-0

ACA anterior cerebral artery, AchA anterior choroidal artery, BA basilar artery, Cl clivus, DS diaphragmasellae, ICAi intracranial portion of the internal carotid artery, OA ophthalmic artery, ON optic nerve,

PcomAf posterior communicating artery (fetal configuration), PcomAn posterior communicating artery (normal configuration), PG pituitary gland, PS pituitary stalk, P1 fi rst segment of the posterior cerebral artery, SCA superior cerebellar artery, SHAs superior hypophyseal arteries, TS tuberculum sellae, IIIcn

oculomotor nerve

The PcomA is the most variable vessel of Willis’s circle. If PcomA is wider than P1, it is said to be of the fetal type. This happens in about 20 % of cases. In 1 % of cases, it is absent (Lang 1995 ) .

Relationship of PcomA & 3rd nerve –parallel or cross each other

Posteior clinoid can be approached in optico-carotid triangle [ 3mm ] OR lateral carotid triangle

Pcom is seen in optico-carotid triangle – can be injured in cisternostomy while cutting lillequet membrane

A 1 [ ACA ] crosses above the Optic tract , not Optic nerve .

Left subchiasmatic cistern

Relationship of PcomA & 3rd nerve – parallel or cross each other in Kernochan's Notch diagram

http://en.wikipedia.org/wiki/Kernohan%27s_notch

Relationship of PcomA & 3rd nerve

Division of PComA

Endoscopic third ventricle from posteriorly -- a. Infundibularrecess b. tuber cinereum c. mammillary bodies

left posterior communicating artery (a), mammillary body (b), and right posterior hypoplasic communicating artery (c) ---measurement performed between the posterior communicating arteries using Geogebra software (a-b = 11.3 mm),

In the descriptive analysis of the 20 specimens, the PCoAsdistance was 9 to 18.9 mm, mean of 12.5 mm, median of 12.2

mm, standard deviation of 2.3 mm.