The Queen of skull base Carotid 360°

21-1-201611.14pm

The Queen Padmini, Rajasthan, Indiahttps://www.flickr.com/photos/bikashputatunda/

5360119800/

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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CAROTID

Fig. 15.10a, b ICA anatomy in lateral (a) and anteroposterior (b) views,showing the seven segments according to Bouthillier’s classification system –

Mario sanna

Cervical segment (C1)

Petrous segment (C2)

Lacerum segment (C3)

Cavernous segment (C4)

Clinoid segment (C5)

Ophthalmic segment (C6)

Communicating segment (C7)

Parapharyngeal carotid

Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal space & becoming Parapharyngeal carotid

12th nerve bissecting internal & external carotid

Internal carotid artery going medial & posterior to medial pterygoid muscle into Parapharyngeal

space & becoming Parapharyngeal carotid

After removing the LPM you will see Tensor veli palatini muscle (TVPM) coming vertically downwards from anterior surface of ET , protecting parapharyngeal carotid

& after TVPM , thick Stylopharyngeal apneurosis (SPHA ) present ANTERIOR to Parapharyngeal carotid [ So 2 structures ( TVPM & SPHA ) protecting parapharyngeal

carotid ]

Hand model --

left hand = medial & lateral pterygoid

right hand = index is parapharyngealcarotid , middle is IJV , ring is styloid & stylopharyngeal muscles , thumb is horizontal carotid

Great vessels , last 4 cranial nerves & sympathetic plexus present in Post-styloid compartment.

https://www.youtube.com/watch?v=onhE4mU98Qo – good video of medial

approach to parapharyngeal space

Transoral approach to SUPERO-MEDIAL Parapharyngealtumors – incision anterior to anterior pillar of tonsil

In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’scanal medial to paraclival carotid ] & 12th nerve

The hypoglossal nerve exits from the hypoglossal canal medial to the ICAp. It lies posteriorly to the vagus nerve and passes laterally between the internal jugular vein and ICAp.

The hypoglossal nerve is usually accompained, within the hypoglossal canal, by an emissary vein and arterial branches from ascending pharyngeal artery and occipital artery.

C1 atlas, Cl clivus, CS cavernous sinus, CV condylar vein, FCB fi brocartilago basalis, HC hypoglossal canal, ICAc cavernous portion of the internal carotid artery, ICAp parapharyngeal portion of the internal carotid

artery, JT jugular tubercle, OC occipital condyle, XIIcn hypoglossal nerve, violet arrow atlanto-occipital joint

Posterior boarder of Lateral Pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose

Endoscopically [ Anterior skull base ] if we follow upper end of LPT posteriorly we can reach V3 [ Posterior boarder of Lateral Pterygoid bone leads to Foramen Ovale –

Dr.Kuriakose ]

Yellow arrow - Bony-cartilagenous junction of ET tube is at posterior genu of carotid - ET is pointing like an

ARROW the posterior genu of internal carotid

V 3 is anteriror to all the 3 structures - Petrous carotid & ET & Parapharyngeal carotid [ very imp ]

Looping / Kinking of Parapharyngeal carotid

KISSING CAROTIDS1. http://radiopaedia.org/articles/kissing-carotids

2. http://www.ncbi.nlm.nih.gov/pubmed/17607445

• The term kissing carotids refers to tortuous and elongated vessels which touch in the midline. They can be befound in:

• retropharynx 2

• intra-sphenoid 1

– within the pituitary fossa

– within sphenoid sinuses

– within sphenoid bones

• The significance of kissing carotids is two-fold:

– may mimic intra-sellar pathology

– catastrophic if unknown or unreported before transsphenoidal / retropharyngeal surgery

Cervical kissing carotids – here also papaphayrngela kinking present http://www.radrounds.com/photo/cervical-kissing-

carotids-1

Coronal MIP of aberrant medial course of the carotids arteries showing the internal carotids arteries nearly touching at the C2 level.

kinking or looping of the ICAp - when looping present para-pharyngeal carotid comes to pre-styloid compartment – previously thought that para-pharyngeal

carotid never comes anterior to styloid mucles – which is UNTRUE

The stylopharyngeus and styloglossus muscles are critical landmarks, being usually placed anterior to the great vessels (Dallan et al. 2011 ).

Note that the presence of kinking or looping of the ICAp could make this statement untrue.

The stylopharyngeus and styloglossus muscles are critical landmarks, being usually placed anterior to the great vessels (Dallan et al. 2011 ).

Note that the presence of kinking or looping of the ICAp could make this statement untrue.

Cervical kissing carotids – here also papaphayrngeal kinking present http://www.radrounds.com/photo/cervical-kissing-

carotids-1

Coronal MIP of aberrant medial course of the carotids arteries showing the internal carotids arteries nearly touching at the C2 level.

An Aberrant Cervical Internal Carotid Artery in the Mouth – we have to be very careful even in adenoidectomy also.

http://amjmed.org/an-aberrant-internal-carotid-artery-in-the-mouth/

In this kinking of ICA also Prof.MarioSanna uses very flexible ICA stents

Relation of Eustachian tube & looping of parapharyngeal carotid & styloid process – loop of paraphyrngeal carotid came anterior

to ET & styloid process – which means when loop present , it comes to pre-styloid compartment

Forceps in ET tube

The external carotid artery passes deeply to the digastric and stylohyoidmuscles, but superficially to the stylopharyngeus and styloglossal muscle

when running toward the parotid gland (Janfaza et al. 2001 ) .

From Aldostamm - Fig. 42.10 - When there is loop of parapharyngealcarotid , it goes nearer to the RCLM or anterior arch of atlas

Anterior view. The right longus capitis muscle has beenremoved. 1, clivus; 2, anterior arch of the atlas; 3, atlantoaxial joint;4, left longus capitis muscle; 5, longus colli muscle; 6, rectus capitis

anterior muscle; 7, carotid artery.

Intratemporal carotid = Horizontal carotid[= Petrous carotid] + Vertical

carotid

Infra-temporal fossa approach The rest of the anterior canal wall has been drilled away, and

the internal carotid artery is better skeletonized. C Basal turn of thecochlea (promontory), ET Eustachian tube, FN(m) Mastoid segment ofthe facial nerve. G Genu of the internal carotid artery, ICA(v) Vertical

segment of the internal carotid artery

To obtain control of the horizontal segment of the internalcarotid artery, the eustachian tube (ET), glenoid fossa bone (GF), and theanterior zygomatic tubercle (AZT) have to be carefully drilled away.ICA Vertical segment of the internal carotid artery

In live surgery, the middle meningeal artery (MMA) should be

coagulated to prevent bleeding. ICA Internal carotid artery, MFP Middle

fossa plate

The middle meningeal artery (MMA) is being sharply cut.

ET Eustachian tube, ICA Internal carotid artery, MFP Middle fossa plate

Further anterior drilling uncovers the mandibular nerve (MN).This nerve also has to be coagulated in live surgery before it is cut.ET Eustachian tube, ICA Internal carotid artery, MFP Middle fossa plate

Sharply cutting the mandibular nerve (MN). ET Eustachian

tube, ICA Internal carotid artery, MFP Middle fossa plate

The stumps of the mandibular nerve (*). ET Eustachian tube,

ICA Internal carotid artery, MFP Middle fossa plate

Endoscopic view of the eustachian tube orifice(arrow).- Note Internal carotid artery

Junction of precochlear & petrous carotid in anterior tympanum

The tensor tympani muscle has been dissected away from itscanal (TTC). ET Medial wall of the eustachian tube, ICA Internal carotidartery, MFP Middle fossa plate

A large diamond burr is used to remove the remaining boneoverlying the horizontal segment of the internal carotid artery. C Basalturn of the cochlea (promontory), ICA Vertical segment of the internalcarotid artery, MFP Middle fossa plate, MMA Stump of the middlemeningeal artery, MN Stump of the mandibular nerve

In Infra-temporal fossa approachThe full course of the intratemporal internal carotid artery hasbeen freed. AFL Anterior foramen lacerum, CF Carotid foramen, CL Duraoverlying the clivus area, ICA(h) Horizontal segment of the internalcarotid artery, ICA(v) Vertical segment of the internal carotid artery,MN Stump of the mandibular nerve

Drilling of the clivus has been completed. C Basal turn of thecochlea (promontory), FN(m) Mastoid segment of the facial nerve,FN(t) Tympanic segment of the facial nerve, GG Geniculate ganglion,GPN Greater petrosal nerve, ICA Internal carotid artery, RW Round window

Pterygoid trigone – just anterior to foramen lacerum in both photos is Pterygoid trigone

Note the Cochlea basal turn anterior wall in left photo

Note that the basal turn of the cochlea (BT) starts to curvesuperiorly near the internal carotid artery (ICA), a short distance

from the level of the round window.

In most cases, the medial aspect of the horizontal portion of the internal carotid

artery is not covered by bone, but simply by dura.

GSPN bisects the Petrous carotid & V3 and Vertical part of Facial nerve bisects Jugular bulb

GSPN bisects V3

In most cases, the medial aspect of the horizontal portion of the internal carotid

artery is not covered by bone, but simply by dura.

Post-operative vasospasm of laceral segment [ carotid mobilization done for tumor removal ]

Paraclival carotid

Paraclival carotid

1. Lower half of paraclivalcarotid - caudal part, the lacerum segment of the artery corresponding to the extracavernous portion of the vessel, and

2. Upper half of paraclivalcarotid - rostral part, the trigeminal, intracavernousportion of the artery, so-called because the Gasserianganglion is posterior to it and the trigeminal divisions are lateral to it.

Pontomedullary junction = Vertebro-basillar junction = Junction of Mid clivus & Lower clivus = foramen lacerum area The pontomedullary junction. The vertebral artery junction is at the level of the

junction of the inferior and midclivus. The basilar artery runs in a straight line on the surface of the pons. The exit zones of the hypoglossal and abducent nerves are at the same level. The abducent nerve exits from the pontomedullary junction, and ascends

in a rostral and lateral direction toward the clivus.

Lower half of paraclival carotid - caudal part, the lacerum segment of the paraclival carotid

”The unsolved surgical problem remains the medial wall of the ICA at the level of the anterior foramen lacerum, until now unreachable with the available surgical

approaches." - In lateral skull base by Prof. Mario sanna – this unreachable is Carotid-Clival window which is accessable in Anterior skull base

Infrapetrous Approach

Carotid-Clival window – Mid clivusa. Petrosal face

b.Clival face

Upper half of paraclival carotid – rostral part, the trigeminalsegment of the paraclival carotid

TG ( Trigeminal ganglion ) is lateral to upper half [ rostral part ] of Paraclival carotid

Anterior skull base Lateral skull base

“Front door” to Meckel’s cave PLL - It can be considered

the border between the horizontal and cavernous portions of the internal carotid artery.

1. 6th N. crossing carotid at Petro-clival junction when viewing in lateral skull base - The lateral aspect of the parasellar & paraclival carotid junction is crossed by the

abducent nerve (VI) at the entrance of both [ 6th nerve & carotid ] structures into the cavernous sinus.

2. The gulfar segment can be identified at the intersection of the sellar floor and the proximal parasellar internal carotid artery (ICA) (Barges-Coll et al. 2010 ).

After drilling the carotid canal what we see is endosteal layer / periosteum , not directly the ICA

Subperiosteal/Subadventitial DissectionSubperiosteal/subadventitial dissection is accomplished for tumors that involve the ICA to a greater extent, such as C2 glomus tumors and meningiomas (Fig. 15.24a, b). In general, dissection of the tumor from the artery is relatively easier and safer in the vertical intrapetrous segment, which is thicker and more accessible than the horizontal intrapetrous segment. A plane of cleavage between the tumor and the artery should be

found first. In most cases, the tumor is attached to the periosteum surrounding the artery. Dissection

is better started at an area immediately free of tumor. Aggressive tumors may, however, extend even to the adventitia of the artery and subadventitial dissection may be needed. This should be done very carefully in order to avoid any tear to the arterial wall, which can become weakened (Fig. 15.25), with the risk of subsequent blowout.

A case of left glomus jugulare tumor in our early experience. ubadventitial dissection has been performed because the artery had been so weakened after the tumor removal. Although the patient had no relevant complications postoperatively, such excessive manipulation is better

avoided and permanent balloon occlusion or stenting are preferably tried preoperatively.

Meckels cave - Trigeminal notch at petrous apex

Carotid nerve

Petrolingual ligament [ PLL ] & Foramen Lacerum [ FL ]

“Front door” to Meckel’s cave PLL - It can be considered

the border between the horizontal and cavernous portions of the internal carotid artery.

PLL = INFERIOR SPHENOPETROSAL LIGAMENTACP anterior clinoid process, APCF anterior petroclinoid fold, DS dorsum sellae, ICF interclinoid

fold, PF pituitary fossa, PLL petrolingual ligament (inferior sphenopetrosal ligament),PPCF posterior petroclinoid fold, PS planum sphenoidale, SSPL superior sphenopetrosal

ligament (Gruber’s ligament), TS tuberculum sellae, black asterisk middle clinoid process

Lingula of sphenoid

SpL = sphenoid lingula

Lingula of sphenoid

Lingula of sphenoid

red asterisk = lingula of the sphenoid

black arrowhead = lingula of the sphenoid

PLL- Petrolingual ligament - considered as a continuation of the periostium of the carotid canal

(Osawa et al. 2008 ) .

Nerves in lateral wall of cavernous in JNA case

Foramen lacerum - The petrous ICA then curves upward above the

foramen lacerum (FL), thus giving the anterior genu. The segment above the FL is not truly intrapetrous, and it has been called the lacerum segment by some authors

(Bouthillier et al. 1996 ) . These segments, the anterior genu and the anterior vertical segment, are placed above the FL, and the artery does not cross the foramen. In this sense, it is better called the supralacerum segment (Herzallah and Casiano 2007 ) .

Anatomically, the FL is an opening in the dry skull that in life is fi lled by fi brocartilagineous tissue (fi brocartilago basalis).

AFL = Anterior foramen lacerum

* [ black asterisk ] = foramen lacerum

Petrolingual area = foramen lacerum

Vidian artery – origin from Laceralsegment

1. The foramen lacerum (FL) is located lateral to the floor of the sphenoid sinus at the level of the spheno-petro-clival confuence.

2. In respect to the FL, the JT is postero-medially located. Therefore toaccess the jugular tubercle from anteriorly a complete exposure of the foramen

lacerum is needed. black asterisk foramen lacerum , JT jugular tubercle, HC hypoglossal canal

Parasellar carotid

Parasellar carotid – shrimp shapedIt covers four segments of the ICA: (1) the hidden segment; (2) the inferior horizontal segment;

(3) the anterior vertical segment, and (4) the superior horizontal segment. The hidden segment is located at the level of the posterior sellar floor and includes the posterior bend of the ICA. The

inferior horizontal segment appears short due to the perspective view, but is the longest segment of the intracavernous ICA. It courses along the sellar floor. The anterior vertical segment

corresponds to the convexity of the C- shaped parasellar protuberance. The superior horizontal segment includes the clinoidal segment which courses medially to the optic strut, is anchored by

the proximal and distal dural ring and continues in the subarachnoid portion of the vessel.

Parasellar carotid

It covers four segments of the ICA:

1. the hidden segment = Posterior Genu– most common injure area .

2. the inferior horizontal segment – The inferior horizontal segment appears short due to the perspective view, but is the longest segment of the intracavernous ICA.

3. the anterior vertical segment, and

4. the superior horizontal segment ( = Clinioidal segment )

Or in another way 1. Retrosellar prominance2. Infrasellar prominance3. Presellar prominance

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.

Retro, Infra, Presellar prominences

A) Cadaveric dissection image taken within the sphenoid sinus, with removal of bone over the lateral sphenoid wall. The paraclival carotid artery (PCA) enters the base of the sphenoid sinus and runs in a vertical direction. At

approximately the level of the V2 (maxillary division of trigeminal nerve) the carotid artery then enters the cavernous sinus and becomes the intracavernous carotid artery (CCA). Once the artery enters the cavernous sinus it continues to

ascend for a short distance, called the vertical portion of the CCA (V. CCA), before turning anteriorly at the posterior genu of the CCA (P. Genu CCA). This posterior genu corresponds to the floor of the sella. The artery then runs

horizontally as the horizontal portion of the CCA (H. CCA), before reaching the anterior

Intrasellar kissing carotid arteries -This anomaly is particularly

important since it may cause or mimic pituitary disease and also may complicate transsphenoidal

surgery.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0004-282X2007000200034&lng=en&nrm=iso&tlng=en

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study - Endoscopic view of the right cavernous sinus and neurovascular relations,

demonstrating the ‘S’ shaped configuration formed by the oculomotor, the abducens , carotid nerve ( paraclival carotid ) and the vidian nerves.

III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducensnerve, C clivus, ICA-Sa anterior bend of the internal carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid

artery, ICA-L lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve

VI nerve is parallel & medial to V1 –in the same direction of V1 [ Mneumonic – VI & V1 in same direction ]

1. 6th N. crossing carotid at Petro-clival junction when viewing in lateral skull base - The lateral aspect of the parasellar & paraclival carotid junction is crossed by the

abducent nerve (VI) at the entrance of both [ 6th nerve & carotid ] structures into the cavernous sinus.

2. The gulfar segment can be identified at the intersection of the sellar floor and the proximal parasellar internal carotid artery (ICA) (Barges-Coll et al. 2010 ).

Carotid nerve –part of S’ shaped configuration formed by the

oculomotor, the abducens , carotid nerve ( paraclival carotid ) and the vidian nerves.

VI nerve is parallel & medial to V1 – in the same direction of V1 [ Mneumonic – VI & V1 in same direction ]

STA is devided into 1. Supra-Trochlear triangle 2. Infra-Trochlear triangle

STA is devided into 1. Supra-Trochlear triangle 2. Infra-Trochlear triangle

1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

3. lower dural ring is COM ( Carotico-Oculomotor Membrane )

In the below picture superior cerebellar artery mislabelled as meningohypophyseal trunk .

STA is devided into 1. Supra-Trochlear triangle 2. Infra-Trochlear triangle

1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

3. lower dural ring is COM ( Carotico-Oculomotor Membrane ) Right lateral view of the inferolateral trunk or artery of the inferior cavernous sinus, a branch of the horizontal part of the internal carotid artery (ICA) that provides blood to the dura of the lateral wall of the cavernous sinus as well as to the cranial nerves running along the lateral wall of the cavernous sinus. The trochlear nerve has been displaced inferiorly and the oculomotor nerve has been displaced superiorly. A recurrent branch from the inferolateral trunk is observed in this specimen. This branch heads back toward the tentorium cerebelli forming the so-called marginal tentorial artery. 1=horizontal segment of cavernous ICA, 2=clinoid segment of ICA, 3=supraclinoid ICA, 4=inferolateral trunk or artery of the inferior cavernous sinus, 5=marginal tentorial artery, 6=optic nerve, 7=oculomotor nerve, 8=trochlear nerve, 9=ophthalmic nerve, 10=abducent nerve, and 11=sphenoid sinus.

1. In the posterior part of the CS the trochlear nerve is below the oculomotor nerve, while anteriorly it turns upward and becomes the most superior structure of the CS (at the level of

the optic strut) (Iaconetta et al. 2012 ) .

2. Trochlear nerve is always superior to V1.

The abducens nerve in most case is a single trunk throughout its entire course (Zhang et al. 2012 ) . There are some variants, and one should be aware that the nerve can fuse with the oculomotor nerve for all its course (Zhang et al. 2012 ) . The surgeon must be prepared to face other rare variations, such as different fasciculi within the CS. Globally, the incidence of a duplicated abducens nerve has been reported, ranging

from 8 % to 18 % (Nathan et al. 1974 ; Iaconetta et al. 2001 ; Ozveren et al. 2003 ) . In the prepontine cistern, when the duplication is present, AICA passes through the bundles. Furthermore, the incidence of a

bilaterally duplicated nerve has been reported as frequently as 8 % of the time (Nathan et al. 1974 ; Ozverenet al. 2003 ) . The abducens nerve can pass above the Gruber’s ligament in 12 % of cases (Lang 1995 ) .

Endoscopic vision of the cavernous sinus. Vision obtained through a right supraorbitalapproach with a 30° down-facing lens focusing on the cavernous sinus

ICAc cavernous portion of the internal carotid artery, lwCS lateral wall of the cavernous sinus, SCA superior cerebellar artery, IIIcn oculomotor nerve, IVcn trochlear nerve, Vcn root of the trigeminal nerve,

VIcn abducens nerve, blue arrow Gruber’s ligament, white asterisk Dorello’s canal.

Blue arrow in Left picture ; * in Right picture - Gruber’s ligament

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study- Endoscopic view of the right cavernous sinus and its

neurovascular relations, demonstrating the triangular area formed by the medial pterygoid process laterally, the parasellar ICA medially and the vidian nerve inferiorly

at the base. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of the internal

carotid artery–parasellar segment, ICA-Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-

L lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study -Endoscopic view of the right cavernous sinus showing its neurovascular

relations and the main anatomic areas. III oculomotor nerve, V1 ophthalmic nerve, V2 maxillary nerve, V3 mandibular nerve, VI abducens nerve, C clivus, ICA-Sa anterior bend of

the internal carotid artery–parasellar segment, ICA Sp posterior bend of the internal carotid artery–parasellar segment, ICA-C paraclival segment of the internal carotid artery, ICA-L

lacerum segment of the internal carotid artery, ICA-P petrous segment of the internal carotid artery, PG pituitary gland, VC vidian canal, VN vidian nerve, STA superior triangular area, SQA

superior quadrangular area, IQA inferior quadrangular area

1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

Branches of cavernous carotid1. Meningohypophyseal trunk

2. Inferolateral trunk

The anterior lobe of the pituitary gland is mainly fed by the superior hypophysealarteries while the posterior lobe is fed mainly by the inferior hypophyseal artery.

Branches of Intracranial carotid 1. Superior hypophyseal Artery

2. Retrograde branch – Opthalmic artery3. Anterior choroidal artery

4. Pcom5. MCA6. ACA

Meningohypophyseal trunk

The MHT is traditionally described as having three branches:

1. the inferior hypophyseal artery, IHA 2. the dorsal meningeal artery (also called the dorsal clival artery) DMA, and

3. the tentorial artery (also called the Bernasconi-Cassinari artery) BCA .

Cadaveric dissection image of the right side of the pituitary gland. Dissection has occurred between the periosteal layer of dura and the meningeal layer of dura (MD) as far posteriorly as

the dorsum sella. The inferior hypophyseal artery (IHA) is visualized asthe base of the posterior clinoid (PC).

Cadaveric dissection image of the pituitary gland tethered from its transposed position by the inferior hypophyseal artery

(IHA). In this image the meningeal and periosteal layers of dura have been removed. The IHA needs to be ligated and cut to allow

complete transposition between the carotid arteries. The dorsum sella (DS) can be visualized. P, pituitary gland; CS, cavernous sinus.

At superior part of Siphon carotid , SHA arises where as inferior part of Siphon carotid MHT [ Inferior

hypophyseal artery ] arises

DMA main feeder of dorellossegement of 6th nerve

DMA main feeder of dorellossegement of 6th nerve

Inferolateral trunk

Inferolateral trunk

Infero-lateral trunk & carotid nerve

In most cases ILT passes superiorly to theabducens nerve (Inoue et al. 1990 ;

Jittapiromsak et al. 2010 ) .

In most cases ILT passes superiorly to theabducens nerve (Inoue et al. 1990 ; Jittapiromsak et al. 2010 ) .

Superior Hypophyseal Arteries [ SHAs ]

The anterior lobe of the pituitary gland is mainly fed by the superior hypophyseal arteries while the posterior lobe is fed mainly by the inferior

hypophyseal artery.

Cadaveric dissection allowing visualization into the subchiasmatic cistern. The superior hypophyseal artery (SHA) can be seen g iving off its chiasmatic (C) and infundibular (I)

branches. ON, optic nerve; OC, optic chiasm; CCA, cavernous carotid artery.

Cadaveric dissection image demonstrating the incised diaphragma (D) to the pituitary stalk (PS). ON, optic nerve; OC, optic chiasm; CCA, cavernous carotid artery.

Superior Hypophyseal Arteries [ SHAs ]- more commonly arise from the paraclinoid ICA - In rare cases SHAs originate

from the intracavernous segment of the ICA

Opthalmic artery

Carotid course – click

• https://www.youtube.com/watch?v=JlNmSI3tS8Q&list=UU3vRSTN8Rx46MQwq06XRJIA

classification of the ophthalmic artery typeshttp://www.springerimages.com/Images/MedicineAndPublicHealth/1-

10.1007_s10143-006-0028-6-1a = intradural type,

b = extradural supra-optic strut type [ Optic strut = L-OCR ]c = extradural trans-optic strut type

on optic nerve, pr proximal ring, cdr carotid duralring= upper dural ring , ica internal carotid artery

I think this variation is type c

In both type a = intradural type,b = extradural supra-optic strut types Opthalmic

foramen is in Optic canal

In Type c = extradural trans-optic strut type , the Opthalmicforamen in Optic strut

http://www.nature.com/eye/journal/v20/n10/fig_tab/6702377f3.html#figure-title

The upper diagram is Type a or b Opthalmic artery , the lower diagram is Type c Opthalmic artery

Dup OC = Duplicate Opthalmiccanal

Origin and intracranial and intracanalicular course of the ophthalmic artery and its subdivisions, as seen on opening the optic canal (reproduced from Hayreh67).

Both from one specimen. (a) The extraduralorigin of the right ophthalmic artery, so that no ophthalmic artery is seen even on opening theoptic canal; a thinning of the dural sheath is seen at 'X', indicating the position of the artery. (b) The ophthalmic artery is seen after removing the duralsheath covering it (reproduced from Hayrehand Dass2).

Schematic drawing origin (a medial, b central, c lateral) and exit(d lateral, emedial) of superior wall of the ophthalmic artery

A diagrammatic representation of variations in origin and intraorbital course of ophthalmic artery. (a) Normal pattern. (b–e) The ophthalmic artery arises from the internal carotid artery as usual,

but the major contribution comes from the middle meningeal artery. (f and g) The only source of blood supply to the ophthalmic artery is the middle meningeal artery, as the connection with the internal carotid artery is either absent (f) or obliterated (g) (reproduced from Hayreh and Dass3).

Origin, course, and branches of the ophthalmic artery in two adult specimens. Segment Y disappeared in (a) and segment Z disappeared in (b), resulting in the ophthalmic artery crossing under the optic nerve in both. In (b) an anastomosis is seen in lateral wall of the cavernous sinus between the part of the internal carotid artery lying in proximal part of the cavernous sinus and a branch from the ophthalmic artery passing through the superior orbital fissure (reproduced from

Hayreh67).

Various relations of OA [ Opthalmic artery ] to ON

left figure when it crosses under the optic nerve (in 17.4%) and right figure when it crosses over the optic nerve (in 82.6%).

Pcom

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 con fi guration), PcomAn posterior communicating artery (normal con fi guration), 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, IIIcnoculomotor 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

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

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

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

Relationship of PcomA & 3rd nerve - Aneurysms of theposterior communicating artery may present with third nerve palsy.

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.

AchA anterior choroidal artery

Usually, the AchA arises from the ICA as a single artery, in most cases close to the PcomA. In rare cases (2 %), it arises from the

PcomA or the MCA (Lang 1995 ; Rhoton 2003 ) . In the great majority of cases, it arises from the cisternal segment of the ICA

lateral to the optic tract and passes below or along the optic tract (usually medially to it) to get the lateral surface of the cerebral

peduncle.

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 con fi guration), PcomAn posterior communicating artery (normal con fi guration), 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, IIIcnoculomotor 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 ) .

In the great majority of cases, it arises from the cisternal segment of the ICA lateral to the optic tract and passes below or along the optic tract (usually

medially to it) to get the lateral surface of the cerebral peduncle.

Division of PComA

Cholesterol granuloma

cholesterol granuloma immediately behind the ICA

Anterior skull base approach Lateral skull base approach

ICA Clin.: clinoid, clinoidal

Dural rings – the ICA between upper & lower dural ring is Clinoidal ICA

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

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

Upper [ green bangle ] & lower dural [ red bangle ] rings

Lower dural ring is nothing but COM [ Carotico-occulomotor membrane ] - The duralining the inferior aspect of the anterior clinoid process forms the lower

dural ring. This ring is often incomplete on the medial side and often a venous channel can follow the paraclinoidal ICA to the upper dural ring.

By Fronto temporal approach

lower dural ring - This ring is often incomplete on the medial side and often a venous channel can follow the paraclinoidal ICA to the upper dural ring.

Clinoid has three roots of attachment 1. Anteriror root = Anterior Clinoid process attachemnt to planum

2. Posterior root = Optic struct = L-OCR 3. 3rd root = Anterior Clinoid process attachment to Lesser wing of sphenoid

Three surgical attachments of the right anterior clinoid process. (a, sphenoid ridge; b, roof of optic canal; c, optic strut.)

Anterior clinoid drilling videos in FTOZ [ neurosurgery skull base ]

1. https://www.youtube.com/watch?v=wO2cWHiOdO0

2. https://www.youtube.com/watch?v=4dkQY3zxJHU

3. https://www.youtube.com/watch?v=vd4_lPVIUvE

4. https://www.youtube.com/watch?v=_dvYB1InGMc

5. https://www.youtube.com/watch?v=83_VuKHXOmQ

6. https://www.youtube.com/watch?v=0KwBhTqNXA4

7. https://www.youtube.com/watch?v=pCURjQ83HzU

8. https://www.youtube.com/watch?v=DNIy0L3oFgY

9. https://www.youtube.com/watch?v=GT4eBB2x58Q

10. https://www.youtube.com/watch?v=OS4Mc0X8tlU

11. https://www.youtube.com/watch?v=_xq9e3p1cc4

blue-sky arrow = upper dural ring,

The lower dural ring is given by the COM [ Carotid-oculomotor

membrane ] , that lines the inferior surface of the ACP. It can be visible, through a transcranial route, only by removing the ACP. The lower dural ring is also called

Perneczky’s ring. Medially the COM blends with the dura that lines the carotid sulcus(Yasuda et al. 2005 )

Endoscopic supraorbital view with a 30°down-facing lens -The right portion of the planum sphenoidale is seen from above.

Right side

Upper & lower dural rings

1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

ICAcl clinoidal portion of the internal carotid artery , The clinoidal segment of the internal carotid artery faces the posterior aspect of the optic strut.

white arrowhead - paraclinoid

portion of the internal carotid artery – after removal of anterior clinoidal process

ICA Clin.: clinoid, clinoidal [ Observe here also – posterior border of Optico-carotid recess is Clinoidal ICA ]

ICA Clin.: clinoid, clinoidal

ICA Clin.: clinoid, clinoidal

ICA Clin.: clinoid, clinoidal

ICA Clin.: clinoid, clinoidal

Cisternal / Intracranial ICA [ICA i]

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.

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 ]

First part of intracranial carotid & paraclinoidalcarotid present in infra-chiasmatic cistern

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

Note the first part of ICAi in chiasmatic cistern in bifrontalcraniotomy approach & note the optico-carotid recess on both sides .

Endoscopic anterior skull base approach

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,

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 ]

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

Surpra petrous approach

Surpra petrous window [ see the GSPN groove here ] ET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA

middle meningeal artery, SPS superior petrosal surface, TI trigeminal impression, V3 thirdbranch of the trigeminal nerve, yellow arrow accessory middle meningeal artery, white

asterisks greater petrosal nerve groove

Infrapetrous approach

Inferior petrosal sinus is superior to jugular tubercle & hypoglossal canal is inferior to jugular tubercle

Infratemporal fossa [=intact cochlear approach – Dr.Morwani ] type B approach

The pontomedullary junction.1. The exit zones of the hypoglossal and abducent nerves are at the same level [ same vertical line when view from Transclival

approah ( through lower clivus ) ] 2. The abducent nerve exits from the pontomedullary junction, and ascends

in a rostral and lateral direction toward the clivus.

In infrapetrous approach there are chances of injury to 6th nerve [ in dorello’scanal medial to paraclival carotid ] & 12th nerve

When we are drilling lower clivus – lateral to hypoglossal canal we get Jugular fossa

Adenoid cycstic carcinoma clivus -- Just look at the carotid. .The paraclival both sides 360 degree encased..look at the mass eroding Petros apex going above horizontal

carotid above the meckels cave..we need a trans cavernous..trans supra Petros. .infra Petros. . App..

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

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

Note the first part of ICAi in chiasmatic cistern in bifrontalcraniotomy approach & note the optico-carotid recess on both sides .

Endoscopic anterior skull base approach

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

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

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

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

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

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

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

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.

Carotid artery bleeding

Various forceps designed to control internal carotid artery bleeding – designed by Prof. PJ

wormald

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