skull base 360°- part 1

SKULL BASE 360° Below presentation is

SKULL BASE 360°-Part 1For

SKULL BASE 360°-Part 2Please click or copy/paste in URL or weblink area

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[ Dated: 21-9-14 ] I will update continuosly with date tag at the end as I am getting more

& more information

Below presentation is

SKULL BASE 360°-Part 1

Endoscopic Lateral Skull base (Neuro-otology)Endoscopic Anterior skull base & Microscopic Lateral skull base &Middle cranial fossa skull base &

Open skull base approaches

Art & Presentation by Dr. N. Murali Chand DLO FHM

Fellowship in HIV medicine, MAMC, New DelhiMy website = www.integratedmedicine.co.in

Cell= +91 99496 77605

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

Approach

1. External corridor doesn’t matter except cosmesis , only internal corridor matters – so in Open approaches of skull

base also use endoscope to get best results – see this video how the Dr. Dugani Suresh ; Neurosurgeon is using

endoscope in Weber Fergusson incision https://www.youtube.com/watch?v=Y95Jf3u8S8o&feature=youtu.be

2. Most of the times “Don’t cross the NERVES”

Prof. Amin Kassam CORRIDOR SURGERY

• Video 1https://www.youtube.com/watch?v=J6ji53nKQy0

Video 2https://www.youtube.com/watch?v=56Wt4vQ9KgE

External carotid artery ligation – Note at division of common carotid , external carotid artery is medial to internal carotid artery – Sometimes the division

may go up very high in neck .

Only to lesion lateral to meridian of pupil in frontal sinus we have to do osteoplastic flap

The landmarks for canine fossa puncture/trephine are the intersection between a vertical line through the pupil and a horizontal line drawn through the floor of the nose.

Enhanced T1-weighted magnetic resonance imaging (MRI),coronal section demonstrates a right nasoethmoidal lesion (adenocarcinoma)

with an “hourglass” intradural extension through the ethmoidalroof. Diffuse enhancement of the dural layer (arrowheads) over

the orbital roof is suspicious for neoplastic spread. The vertical lines limitthe area of the dura safely resectable by a pure endoscopic approach.

“Up & below” approach to frontal sinus

Illustration of the septal incisions necessary to achieve good access to the entire anterior wall of the maxillary sinus for

tumors either originating from this region or with a significant anterior wall attachment. (B) Cadaveric image demonstrating the access to

the anterior wall (AW) of the maxillary sinus with a 70-degree diamond drill (D).

(A) The microdebrider blade has been passed through an inferior meatal antrostomy. Note the anterior fulcrum (nasalvestibule, broken white arrow) and the posterior fulcrum (inferior meatal antrostomy, white arrow). The region of the maxillary

sinusthat can be cleared through this access is shaded. This shaded region is smaller with a middle meatal antrostomy. The single

fulcrum ofthe canine fossa puncture is indicated (white arrow) (B,C,D), illustrating how the entire maxillary sinus can be accessed as the

bladeonly has a single fulcrum.Medial , posterior & Lateral walls approached through Caldwel-luc

The red arrows demonstratethe endonasal approach, and the green arrows represents the transmaxillary

approach. The blue rectangle shows the parasellar structures.A more perpendicular angle of attack is achieved in the transmaxillaryapproach, and the distance to the target from this route is equal to or

smaller than that in the endonasal approach. Temp.: temporal.

Note that in the transmaxillary approach thestructures in the lateral wall of the sphenoid sinus are seen in a

moreperpendicular way, facilitating dissection of this region.

Close-up view of the cavernous sinus through the transmaxillary

approach. Gasser.: gasserian.

The pink and orange linesdemonstrate the possible angles of maneuver in transmaxillary

approach.In green is emphasized the possibilities of resection through

transmaxillary approach.

General view of the radial endoscopic accesses to the skullbase --- The green arrows represent the endonasal approaches,

the red arrows represent the transmaxillaryapproaches, and the purple arrows represent the

subtemporal approaches. Note the multiple possibilitiesof combination of these approaches.

Modified denkers approach - Blue dotted line showsthe medial maxillary wall. (B) Panoramic view after removing the medial

maxillary wall. Yellow dotted line shows the connected nasal cavity with maxillary sinusthe maxillary sinus.

Schematic demonstrating how the removal of the lateralaspect of the piriform overture (in the red circle) enables a wider approach

(the green cone compared with the yellow cone) to the lateralregions (pterygopalatine and infratemporal fossa).

Use combination of approaches when ever it is necessary - Combined Transmastoid Middle Cranial

Fossa Approach

Rt lower cranial nerve shwannoma, which approach will be better ,which approach will be better considering this side is

dominant sinus.

Answer • Amit Keshri says - eight nerve was normal,so was 7th,removed tumor

completely with retrolab approach and to get space,the sigmoid plate was decompressed and sinus retracted posteriorly after RMSO [ Retro mastoid sub-occipital ] craniotomy without opening dura posteriorioly.

• Murali Chand Nallamothu For lower cranial nerve schawnnoma POTS approach is the best - but here you are saying it is dominent sinus , no need to sacrifice sigmoid sinus -- so in this case we can use extended translabyrinthine approach for the AFB area part & at carotid canal area part of the tumor can be removed by externally which is included in the lower C - shaped incision

• Murali Chand Nallamothu if the 8 th nerve is good we can try retrolabyrinthinne & retrosigmoid approach & take the help of endoscope.

• Post-op :

Posterior wall of maxillary sinus

Periosteum after removal of posterior bony wall of maxillary sinus – this periosteum must be removed in JNA

MPP/VNLPP/V2

Anteriorly MPP & LPP are fused & posterioly only they are divided .

Erosion of right greater wing of sphenoid in a case of maxillary carcinoma

Medial pterygoid is in line with lateral wall of Sphenoid -- The superior vertical limb represents the paraclival ascending carotid and the

descending vertical limb is represents the medial pterygoid plate. The horizontal bar of the ‘H’ is represented by the sphenoid sinus floor.

Lateral part of Posterior choanae is MPP

ET is just posterior to MPP

Lateral part of Posterior choanae is MPP

Medial pterygoid is in line with Paraclival carotid

Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]

Zygomatic nerve [ ZN ]

Infraorbital groove near inferior orbital fissure – If we drill supero-lateral to infraorbital nerve it is nothing but Inferior orbital fissure .

Infraorbital groove near inferior orbital fissure – If we drill supero-lateral to infraorbital nerve it is nothing but Inferior

orbital fissure .

Red ring = V2

Inferior orbital foramen continues as pterygomaxillary fissure .

One line along Vidian nerve & another line along V2

Lateral to LPP & infra-orbital nerve [ or V2 ] is Infratemporal fossa

One transverse line from Vidian nerve connecting vertical line of V 2 & another transverse line from V2

The space above transverse line of Vidian nerve is Pterygoid Recess of sphenoid – Read the CT – scan/ Plane the surgery by using these lines

The space above transverse line of V2 is Middle cranial fossa ( Meckel’s cave ) –

Read the CT – scan/ Plane the surgery by using these lines

Pterygo-palatine fossa

Pterygopalatine fossa. A, V2 (blue dotted line) coming outfrom the foramen rotundum; B, green-yellow dotted line shows the

pterygopalatine ganglion; C, yellow dotted line shows the vidiannerve; D, red dotted line shows the sphenopalatine artery; E, light bluedotted line shows the great palatine nerve; F, white dotted line showing

the infraorbital artery.

EC – Ethmoidal crest – left nose

PVC , VC & FR are in 45 degree angle line

Endoscopic view of PPG

Tracking of infraorbital nerve leads to V2 & tracking of V2 leads to Trigeminal ganglion/ Middle cranial fossa [ one of the best way to track middle crannial fossa is to track V 2 ]

Zygomatic nerve [ ZN ]

Endoscopic view of foramen rotundum area

Infratemporal fossa

Lateral pterygoid muscle devides internal maxillary artery into 3 parts

1. The maxillary artery & Buccal nerve enters the infratemporal fossa between the superior and inferior head of the

lateral pterygoid muscles. 2. Lingual nerve & Inferior alveolar nerve comes between medial pterygoid & lateral

pterygoid mucles .

Anteriorly lingual nerve & posteriorly Inferior Alveolar nerve coming lateral to medial pterygoid muscle

Forceps behind IAN Forceps behind LN

IAN = Inferior alveolar nerve

Triangle formed by temporalis muscle , MPM & LPM

Mandibulotomy approach Endospic view

Post-maxillectomy “Fat pad” over temporalis muscle – which is seen as Fat Pad [ FP ] in the triangle formed by temporalis mucle ,

MTM & LPM endoscopically

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

becoming Parapharyngeal 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 ]

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 present ANTERIOR to Parapharyngeal carotid -- Attached to this ET cartilage [ TP/ET attachment ] is the tensor palatini

(TP) fibrous aponeurosis (solid white line) with its muscle fibers seen below (broken white line).

Hand model --

left hand = medial & lateral pterygoid

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

Parapharyngeal space

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

becoming Parapharyngeal carotid

Post-styloid compartment = carotid space

Sphenoid osteum

Sphenoid osteum present at the juction of upper 2/3rd & lower 1/3rd junction of Superior turbinate – this

became very useful to me in extensive fungal sinusitis with polyposis & bleeding.

Three sequential indentations are made with the blunt end of the 4-mm microdebrider blade starting at the medial upper limit of

the posterior bony choana and moving directly superiorly medial to the cut edge of the superior turbinate.

L-OCR & M-OCR

L-OCR – Triangle 1. Upper boarder – Optic nerve & Opthalmic artery

2. Posterior boarder – Clinoidal carotid 3. Lower boarder – 3rd N. in deep & 6th N. superficially

[ 6th N. & 4th N. & V1 present inferior to 3rd N. ]

The bone of the anterior clinoid (AC) process has been left in place, positioned within the lateral opticocarotid recess.

L-ocr is the space in Optic strut - not the space in Anterior clinoid process

classification of the ophthalmic artery types http://www.springerimages.com/Images/MedicineAndPublicHealth/1-10.1007_s10143-006-0028-6-1

a = intradural type,

b = extradural supra-optic strut type [ Optic strut = L-OCR ]c = extradural trans-optic strut typeon optic nerve, pr proximal ring, cdr carotid dural

ring= 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 Opthalmic foramen in Optic strut

L-ocr is the space in Optic strut - not the space in Anterior clinoid process

Note Optic strutNote Optic strut- Right Optic nerve Anterio-superior view

Pneumatization of anterior clinoid process – in various planes + onodi cell on both sides of sphenoid [ when transverse septum present in sphenoid it is

onodi cell ] + sphenoid recess on left side between V2 & VN .

The same cadaver photo what you are seeing in CT scan above – Note the supraoptic pneumatisation [ present in anterior clinoid process ] in an onodi cell .

ICAcl clinoidal portion of the internal carotid artery , The clinoidalsegment of the internal carotid artery faces the posterior aspect of the optic

strut [L-OCR ]

Red ring – Pneumatization in Optic strut – which is nothing but L-OCR

M-OCR is nothing but Middle Clinooid Process [ indicated by Green Button in both photos ]

The mOCR is located just medial tothe 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

The mOCR is placed at the confluence of the sella, tuberculum sellae, carotid protuberance, opticcanal and planum sphenoidale. The mOCR corresponds to the lateral extent of the tuberculum

sellae. ---- white asterisk lateral opticocarotid recess, white circle medial opticocarotid recess ---

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 ).

Limits of the bone resection – Inner ring in below photo• Posterior ethmoidal arteries

• Medial OCRs

SIS & IIS

SIS – superior intercavernous sinus & IIS – inferior intercavernous sinus

1. Note ASIS & PSIS2. Note Subarachnoid space at antero-superior area , which is the potential

CSF leak area in pituitary surgery .

PSIS – Posterior superior intercavernous sinus ASIS & PSIS together called CIRCULAR SINUS

Cavernous Sinus

Right cavernous sinus dissection. The quadrilateral delimits the right cavernous sinus area.a Before periosteal layer removal. b After periosteal layer removal. c Cavernous sinus

compartments.L = Lateral; AI = anteroinferior; PS = posterosuperior compartment of the cavernous sinus (the

medial is a virtual space in continuity with the AI and PS).

CS divided into four virtual compartments: 1. medial, 2. lateral,

3. posterosuperior, and4. anteroinferior

Medial and posterosuperior compartments are in strict continuity and do not contain nerves, representing a surgical corridor without risk of neural damage. The anteroinferior and lateral compartments contain the abducens nerve and, as surgical corridors, they are exposed to the

riskof injury to the VIth nerve.

Clivus

1. Upper Clivus2. Middle Clivus3. Lower Clivus

Basi occiput & basi sphenoid

Groove for medulla on Lower Clivus [ = Basi Occiput ]

The 6 linear landmarks of the PCF superimposed on a midsagittal T1-weighted MR imaging from a patient with CMI: herniation (HR), McRae line (MC), clivus (CL), Twining

line (TW), cerebellum (CR), and supraocciput (SO).

http://www.ajnr.org/content/34/9/1758.figures-only?cited-by=yes&legid=ajnr;34/9/1758

1. Upper clivus – Upto 6th nerve entry dorello’s canal (petro-clival junction) 2. Middle clivus – from 6th nerve to jugular foramen

3. Lower clivus – from jugular foramen to foramen magnum

Pneumatization of the sphenoid sinus

The middle third (M. 1/3rd) begins at the sellafloor (SF) and extends to the floor of the sphenoid sinus (SSF), and the lower

third (L. 1/3rd) extends from the floor of the sphenoidsinus to the foramen magnum (FM).

Infrapetrous ApproachCarotid-Clival window – Mid clivus

a. Petrosal faceb.Clival face

See the lower clivus relation to the cochlea

In conchal sphenoid surgical landmarks –

1. posterior end of vomer or keel of sphenoid tells about the position of pituitary

2. lateral boarder of posterior choana [ or MPP ]tells about paraclival carotid & sellar carotid C-SHAPE convex is lateral to this line

3. posterior lower boarder of vomer is at the junction of middle & lower 1/3rd clivus & it is exactly at foramen lacerum –my understanding

See the relationship between lower boarder of posterior end of vomer & clivus – vomer lower boarder is at junction of mid & lower clivus – my

understanding

http://www.neurosurgicalapproaches.com/2013/08/25/

Anterior cranial fossa dura Posterior cranial fossa dura

Very rare specimen..The vbj is far inferior to floor of sphenoid sinus

The foramen lacerum (FL) is located lateral to the floor of the sphenoid sinus at the level of the

spheno-petro-clival confuence. JT jugular tubercle, HC hypoglossal canal –

addFig 3.78 also

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

Inferior clival line (Fernandez-Miranda et al. 2012 ) The longus capitis and rectus capitis anterior muscle attach on the inferior surface of

the clivus. Below the RCAM the occipito-cervical joint capsule lies. The area of attachement of the RCAM has been named inferior clival line (Fernandez-Miranda et

al. 2012 ) and correspond to the supracondylar groove (that is a landmark for the hypoglossal canal).

Transcochlear approach

Note CL [ Lower clivus ] in these photos after drilling of cochlea

Note CL [Lower clivus ] in these photos after drilling of cochlea

The clivus bone (CL) can be seen medial to the internal carotidartery (ICA). JB Jugular bulb

In the lower part of the approach, the glossopharyngeal nerve(IX) can be seen. V Trigeminal nerve, VIII Cochlear nerve, AICA Anteriorinferior cerebellar artery, CL Clivus bone, DV Dandy’s vein, FN Facialnerve, FN(m) Mastoid segment of the facial nerve, FN(t) Tympanic segmentof the facial nerve, GG Geniculate ganglion, ICA Internal carotidartery, JB Jugular bulb, MFD Middle fossa dura, SCA Superior cerebellarartery, SS Sigmoid sinus

BT- basal turn of the cochleaFig. 8.34 The bone medial to the internal carotid artery (ICA) has beendrilled and the clivus bone (CL) has been reached. FN Facial nerve,JB Jugular bulb

Note cochlear aqueduct [ CA ]Here ICA is vertical part of carotid infront to cochlea – this is not paraclival carotid

Note CL [ clivus ] in these photos after drilling of cochlea

Note the contralateral vertebral artery [ CVA ] in below photo

Lower clivus in Infratemporal fossa approach

PVC – is occupied by Ascending palatine artery (APA)

Craniopharyngioma removal - Lilliquest membrane & Basillar artery

V3 & MMA

V 3 falls like niagara falls from middle cranial fossa to infratemporal fossa 90 degrees away from V1 & V2 – it is anterior to all the 3

structures , Petrous carotid & ET tube & Parapharyngeal carotid

ATN = Auriculotemporal nerve

IAN = Inferior alveolar nerve

My forceps touched the lingual nerve , posterior to this LN is Inferior alveolar nerve – These two nerves present in triangle

formed by medial pterygoid , lateral pterygoid & temporalis muscle

Chorda[CT] attached to LN

Schematic diagram for infratemporal fossa approach

Sometimes V3 can be seen in the sphenoid sinus – in “pneumosinus dilatans multiplex”

The greater wing of sphenoidal is almost completely pnematised. So is the temporal bone on the left.the Left carotid can be traced from the middle ear to the sphenoid - in “pneumosinus dilatans

multiplex”

V3 & MMA

V3[MN] & MMA & ET in lateral & Anterior skull base – see the relationship of ET tube which is medial to V3 & MMA

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

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 ]

In Infratemporal fossa approach- Posterior boarder of Lateral pterygoid bone leads to Foramen Ovale [ FO ] – Dr.Kuriakose

V3 is anterior (infront) to Horizontal carotid (= Petrous carotid ) & ET – It cause indentation on the

ET also .

In open approaches in maxillary swing approach as long as you stay lateral to ET you will not injure the

horizontal part of carotid

Petrous carotid & paraclival carotid is SADDLE shape – LEG of the rider is V3

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

V3 is an important landmarkto locate the post-styloid compartment, as it is anterior

to this space (Falcon et al. 2011 ) .

TP & LP

See the relationship of MPP & TP which is just posterior

Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may extend laterally and involve this sinus involving the Mandibular nerve. This produces a triad of symptoms known as Trotter's

triad [ 1) Conductive deafness ( due to eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain in the distribution of V3 ]

See the relationship between LPP & V3 which is just posterior

Eustachian tube

ET is just posterior to MPP [ Lateral part of Posterior choanae is MPP ]

ET is just posterior to MPP

ET is pointing like an ARROW the posterior genu of internal carotid [ ICAp & CF is parapharyngeal

carotid ]

Sinus of Morgagni - In nasopharyngeal carcinoma, the tumor may extend laterally and involve this sinus involving the Mandibular nerve. This produces a triad of symptoms known as Trotter's

triad [ 1) Conductive deafness ( due to eustachian tube involvement) 2) Ipsilateral immobility of soft palate 3) Neuralgic pain in the distribution of V3 ]

black asterisks medial corridor to ICAp – TVPM attached to anterior surface of ET – so if we go inbetween MPM & TVPM we

reach to ICAp

Bony-cartilagenous junction of ET tube is at posterior genu of carotid - ET is pointing like an ARROW the

posterior genu of internal carotid

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 ]

ET tube in SPF [Spheno-petrosal fissure]

At bony-cartilagenous junction of ET tube – Horizonal carotid & Parapharyngeal carotid is above & below ET - My understanding

In open approaches in maxillary swing approach as long as you stay lateral to ET you will not injure the

horizontal part of carotid

Fossa of Rossenmuller apex is laceral carotid [ Foramen Lacerum ] pharyngeal recess (fossa of Rosenmüller), which projects laterally from the

posterolateral corner of the nasopharynx with its lateral apex facing the internal carotid artery laterally and the foramen lacerum above;

endonasal approaches to expose thearea between the ICAs belong to the sagittal plane, and the

approachesaround the ICA define the coronal plane modules.

Note that the eustachian tube indicates the carotid canal only approximately. In other words, it lies ona different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it covers the vessel for all its

length. -- Medially the space between these two CORONAL planes is nothing but Fossa of Rosenmuller [ My understanding ]

Note that the eustachian tube indicates the carotid canal only approximately. In other words, it lies on

a different CORONAL plane in respect of the vessel, and from an anterior viewpoint, it covers the vessel for all its

length. -- Medially the space between these two CORONAL planes is nothing but Fossa of Rosenmuller [ My understanding ]

Surgeons should have in mind that the external orifi ce of the carotid canal is not on the same

coronal plane of the foramen lacerum (anterior genu). It is by far more posteriorly located.

SOF [ Superior Orbital Fissure ]

Parts of SOF 1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal

N.,Trochlear N. 2.Middle part

3. Medial/Inferior part

Parts of SOF 1. Lateral part- LFT [ Liver functional tests ] Menumonic – Lacrimal N., Frontal

N.,Trochlear N. 2.Middle part

3. Medial/Inferior part

Accessing intraconal lesions endonasally requires manipulation of the extraocular muscles. The nerve branches that supply the oculomotor muscles run in the medial

surface of the muscles. Thus, try to avoid excessive retraction of the extraocular muscles to avoid inadvertent muscle paresis.

SOF is the space between two Structs – Superiorly OS [ Optic Strut ] & Inferiorly MS [ Maxillary Strut ]

Anterior view of SOF Posterior view of SOF

Yellow line = “nasal” part of SOF Clinically, the SOF and CS apex represents a continuum.

endoscopic endonasal viewpoint the nasal window to SOF is above V2, and below the lateral

optico-carotid recess.

blue-sky arrows SOF ; MS-Maxillary strut ; MP-Maxillary prominence

Zonule of zinn - inserts on the infraoptic tubercle, which is often found as a canal located beneath the optic strut .

The structure Infero-lateral to SOF is – Horizontal part of carotid

Anterior to L-OCR is Superior Orbital Fissure

SOF - Anterior

SOF - Posterior

MS- Maxillary strut /// Averagedistance from the FR at PPF and the vertical segment of ICAc is

35 mm [ 3.5cm ] (Amin et al. 2010 ) .

SOF , Middle Fossa , V3 in line vertically

GSPN-VIDIAN NERVE

GSPN passes above Horizontal [=petrous] carotid & passes underneath V3 & crosses petro-paraclival carotid junction at

foramen lacerum before becoming vidian nerve

The bone overlying the internal auditory canal has been removedand the dura of the canal has been removed near the fundus. The

facial nerve (FN) can be seen entering its labyrinthine segment to form thegeniculate ganglion (GG) more laterally. V Trigeminal nerve, < Acousticofacial

bundle, C Cochlea, ET Eustachian tube, GPN Greater petrosalnerve, I Incus, IAC Internal auditory canal, ICA Internal carotid artery,

M Malleus, SSC Superior semicircular canal, SV Superior vestibular nerve

Observe the relationship between GSPN & horizontal carotid

Fig. 2.62 The course of the horizontal segment of the internal carotidartery (ICAh), as seen from the middle cranial fossa of a left temporalbone. VI Abducent nerve, C Cochlea, GPN Greater petrosal nerve, IAC

Internal auditory canal, ICA(ic) Intracranial internal carotid, M Mandibularnerve, MMA Middle meningeal artery, MX Maxillary nerve

Fig. 5.47 The view after completion of the middle crannial fossa approach. AE Arcuate eminence,BB Bill’s bar, C Cochlea, FN(iac) Internal auditory canal segmentof the facial nerve, FN(t) Tympanic segment of the facial nerve,

G Geniculate ganglion, GPN Greater petrosal nerve, I Body of the incus,L Labyrinthine segment of the facial nerve, M Head of the malleus,

MFD Middle fossa dura, SVN Superior vestibular nerve

In Infratemporal fossa - Note that the greater petrosal nerve (GPN) is adherentto the dura, and that retracting the dura will lead to stress on thefacial nerve at the geniculate ganglion (GG) level. Thus, if dural retractionis needed, cutting the petrosal nerve will prevent this injury.

In middle cranial fossa – same point

Foramen lacerumAFL = Anterior foramen lacerum

* [ black asterisk ] = foramen lacerum

Petrolingual area = foramen lacerum

After elevating V3 anterior[infront] to ET & petrous carotid observe -- GSPN continues as VN [ VN is lateral to paraclival

carotid ]

GSPN & GSPN groove in Surpra petrous windowET 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

Vidian nerve is formed by GSPN & Deep petrosal nerve – so GSPN (passes underneath V3) crosses laterally the Horizontal carotid and paraclival carotid

junction (Prof.Kassam) & continues as Vidian nerve

Blue arrow – LPN & Yellow arrow – GPN

Trans-pterygoid approch-- Vidian Artery present in 60% & enters at the junction of Horizontal carotid & paraclival carotid – it is present above the Vidian nerve so while drilling vidian canal in

JNA first we have to drill inferior half and then upper half [the bone around the vidiancanal is drilled along its inferior half (from 3 o’clock to 9 o’clock) until the carotid

artery is identified at the lacerum segment ]

Vidian nerve - lateral to paraclival carotid & medial to FO [ Foramen Ovale ]- actually it is

Vidian canal & Spheno-palatine foramen are in 90 degrees

Vidian nerve - lateral to paraclival carotid

Close vision of the middle cranialfossa. The gasserian ganglion has been removed

Vidian nerve - lateral to paraclival carotid

Axial T2-weighted magnetic resonance imaging (MRI) sequence at the level of the vidian canal: 1, clivus; 2, pterygoid; 3,

horizontal tractof the internal carotid artery (ICA); 4, vidian canal.

Infratemporal fossa approach type C

Foramen lacerumAFL = Anterior foramen lacerum

Vidian artery – origin from Laceral segment

Lateral Recess is the space between V2 & Vidian nerve .

Courtesy – Dr. Satish Jain , Jaipur

Lateral Recess is the space between V2 & Vidian nerve .

Here TI [ trigeminal impression ] is V2

LRSS = Lateral recess of the sphenoid sinus

Floor of Lateral recess is by ET ---- BS basisphenoid, ET eustachian tube, LRSS lateral recess of the sphenoid sinus, OPPB orbital

process of the palatine bone, PVA(s) palatovaginal artery(ies), RPm rhinopharyngeal mucosa,SPAib inferior branch of the sphenopalatine artery, SPPB sphenoidal process of the palatine bone,

SS sphenoid sinus, RS rostrum sphenoidale, VN vidian nerve

Surpra petrous windowET eustachian tube, GPN greater petrosal nerve, MCFd dura of the middle cranial fossa, MMA

asterisksgreater petrosal nerve groove

Carotid nerve

Middle cranial fossa approach

The middle fossa retractor is fixed at the petrous ridge (PR).AE Arcuate eminence, GPN Greater petrosal nerve, M Middle meningealartery

The expected location of the internal auditory canal (IAC).The bar-shaded areas are the locations for drilling. A Anterior, AE Arcuateeminence, GPN Greater petrosal nerve, MMA Middle meningealartery, P Posterior

Petrous apex bone

Petrous apex - Quadrangular area

Petrous apex – Triangular area

Triangles

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- Endoscopic view of the right cavernous sinus and neurovascular relations, demonstrating the ‘S’ shaped configuration formed by the oculomotor, the abducens and the vidian nerves. 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

6th nerve is parallel to V1 – in the same direction of V1

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

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

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 area1.Supra Trochanteric & Infratrochanteric Triangles2. Upper & lower dural rings

http://www.slideshare.net/INUB/endoscopic-anatomy-and-approaches-of-the-cavernous-sinus-cadaver-study - Endoscopic view (a), and a drawing (b) of the right cavernous sinus demonstrating its

neurovascular relations. c A drawing of the right cavernous sinus demonstrating the exposure of the trochlear nerve after retracting the oculomotor nerve. III oculomotor

nerve, IV trochlear nerve, V1 ophthalmic nerve, VI abducens nerve, ICA internal carotid artery, OA ophthalmic artery, OCh optic chiasm, ON optic nerve, PG pituitary

Triangles of cavernous sinus – see Ant. Medial & Ant. Lateral triangles in both photos. http://www.eneurosurgery.com/surgicaltrianglesofthecavernoussinus.html

Postero-medial Triangle = KAWASE triangle [Prof.KAWASE , JAPAN Neurosurgeon -below photo]

Fig. 22.31 Clinoidal and oculomotor triangles have been opened and the anterior clinoid removed up to the optic strut, exposing the carotido-oculomotor membrane. The optic strut has two neural-facing surfaces( yellow dotted lines) and one vascular-facing surface (red dotted line). CN: cranial nerve; Falc.: falciform; ICA: internal carotid artery; Inf.:inferior; Lig.: ligament; Pet.: petrosal; V1: first division; V2: second division; V3: third division of trigeminal nerve.

ACP 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

Opticocarotid traiangle by Pterional approach

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 be found 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.

An Aberrant Cervical Internal Carotid Artery in the Mouth

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

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

Looping / Kinking of Parapharyngeal carotid

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 styloglossusmuscles 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 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.

An Aberrant Cervical Internal Carotid Artery in the Mouth

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

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

Relation of Eustachian tube & looping of parapharyngeal carotid & styloid process

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

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

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

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

fromthe 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 & Vertical part of Facial nerve bisects Jugular bulb

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

TG ( Trigeminal ganglion ) is lateral to Paraclival carotid

After drilling the carotid canal what we see is endosteal layer , not directly the ICA – Dr.Janakiram

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.

Fig. 15.25 A case of left glomus jugulare tumor in our early experience.Subadventitial dissection has been performed because the artery had

been so weakened after the tumor removal. Although the patient had norelevant complications postoperatively, such excessive manipulation is

better avoided and permanent balloon occlusion or stenting are preferablytried preoperatively.

Meckels cave - Trigeminal notch at petrous apex

Carotid nerve

Petrolingual ligament [ PLL ] & Foramen Lacerum [ FL ]

Lingula of sphenoid

red asterisk = lingula of the sphenoidblack arrowhead = lingula of the sphenoid

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

(Osawa et al. 2008 ) .

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

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

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

Vidian artery – origin from Laceral segment

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

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

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.

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

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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

Branches of cavernous carotid1. Meningohypophyseal trunk

2. Inferolateral trunk

Branches of Intracranial carotid

1. Superior hypophyseal Artery

Superior Hypophyseal Arteries [ SHAs ]

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

from the intracavernous segment of the ICA

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 .

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

hypophyseal artery ] arises

DMA main feeder of dorellos segement of 6th nerve

Inferolateral trunk

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 ) .

Cholesterol granuloma

cholesterol granuloma immediately behind the ICA

ICA Clin.: clinoid, clinoidal

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

Lower dural ring is nothing but COM [ Carotico-occulomotor membrane ] - The dura lining 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.

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 - paraclinoidportion 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

Intracranial portion of 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 ).

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 ]

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 ]

Pterional

CRANIOPHARYNGIOMAS-Removal corridors.

Cyst of craniopharyngioma

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

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’s canal 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 intracranialexposure of the frontal lobe and easy access to the optic

nerves, the chiasm, the carotid arteries and the anterior communicatingcomplex

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 pterional craniotomy utilizes a frontotemporal incision and removal of the frontal and temporal bones andsphenoid wing. The pterional craniotomy primarily exploits the sylvian fissure

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 optocarotid area. b Displacing medially the posterior communicating artery, exposing the

contents of the interpeduncular cistern. AC anterior clinoid, AchA anterior choroidal artery, 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 hypophyseal artery, 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, AcoA

anterior 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 cerebellar artery,

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. 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. 4.12 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 orbitozygomatic transcavernous approach

COM= Caratico-occulomotor membrane , 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 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 posterolateral choroidal 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 Atraumatic suction. 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 clinoid process.

Carotid artery bleeding

SKULL BASE 360° Above presentation is

SKULL BASE 360°-Part 1For

SKULL BASE 360°-Part 2Please click or copy/paste in URL or weblink area

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[ Dated: 19-4-14 ] I will update continuosly with date tag at the end as I am getting more

& more information

skull base 360°- part 1

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pure endoscopic approach

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presentation isskull

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