Endoscopic lateral skull base

16-4-201711.23 pm

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Some of these slides belongs to ENT proper so Neurosurgeons please skip those slides &

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Great teacher Dr. Sree Ram Murthy MS (ENT) FRCS ; INDIA – so many photos in this presentation are his work - https://www.facebook.com/sreeram.murthy.52

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

FACIAL RECESS

• DEAR SURGEONS FACIAL RECESS, other side of coin if you see the facial recess from ear side it is facial sinus you can observe the sius how big it is tha course of vertical facial nerve and all other structures we have taken the pic in reverse sitting position it is for residents only for understanding retro tympanum FN decompression is easy in this position

1) I S joint 2) pyramidal tip 3) ponticulus 4) facial sinus 5) sinus tympani 6) chordal crest 7) fossula of Grivot Red dotted lines vertical FN

Some thing different..can we do wonders edoscopically with reverse position?Answer is yes...

Endoscopic ear surgeons try stapideoplasty in this position and see how easy the surgery is..

1) I S joint 2) pyramidal tip 3) ponticulus 4) facial sinus 5) sinus tympani 6) chordal crest 7) fossula of Grivot Red dotted lines vertical FN

This is how we see

1) I S joint 2) pyramidal tip 3) ponticulus 4) facial sinus 5) sinus tympani 6) chordal crest 7) fossula of Grivot Red dotted lines vertical FN

Here sinus tympani is actually facial recess .

The point which I want to highlight in this diagram is - lower point of henles spine is exactly in line with 2nd genu - so when you are going deeper and deeper in cortical don't drill below/ nearer to lower point of henles spine , you may hit the 2nd genu . Always drill above henles spine . This is very useful in 1. Children 2. Contracted antrum

Encounterd an interesting abnormality of the facial nerve while doing cortical mastoidectomy...... the facial nerve was exposed in its 2nd genu with hump formation which was blocking the ventilation pathway in the attic region.....the bony ridge that is seen was cleard and the attic widened to establish the ventilation pathway.... sorry for

the poor picture quality.....https://

www.facebook.com/photo.php?fbid=528275190567736&set=gm.466345266781574&type=3&theater

Geniculate crest

geniculate crest• Dear ent surgeons it is a geniculate crest a sharp bony crest between 1st

and 2nd part if facial nerve A rare picture we did it endoscopic cadaveric dissection It is one of the 10 commandments of Fisch you know other nine

• Geniculate crest continue downwards and forms Bils bar we lifted f n to show crest Traumatic f n palsies occur at pergeniculate areas because the crest so sharp like knife and ganglion is fixed between 3 points 1 deep labyrinthine part 2 deep gutter like pre cochleariform part if h f n 3 at foramen of Henli U can observe geniculate crest clearily in microscopic t b dissection we cannot see crest clearly u can observe poramen of Henli clearly here facial nerve decompressions concentrate onthis crest during decompression Dear residents u ask t b dissection surgeons to show this structure during dissection course it is useful

10 mm RULES

Dear surgeons there are 1 to 10 mm rules in temporal bone surgery If surgeon follows those rules the ear surgery is easy and methodical. In temporal

bone no structure is more than 10 mm in length.

10 MM RULES and 5 COLLARS OF BONE

• 10 MM RULES and 5 COLLARS OF BONE Dear Otologists..There are 5 collars (colour) of bone and 10 mm Rules (1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm,10mm) present in ear and temporal bone surgery-There is thin bony collar surrounding the important structures of the ear like the collar of the neck, with particular different colours. after visualising the color of the bone the surgeon can identify the structure deep to the collarthe collars are.. 1) Red spongotic collar - Jugular bulb2) Pink collar - Dura3) Blue collar - Sigmoid sinus4) Yellow collar - Internal Auditory Canal5) White ivory collar - Bony labyrinth

1 mm rule

• 1 mm rule

In posterior part of attic, tegmen is high where as in anterior part of attic tegmen slops down to join tensor canal Here the rule of "1" is applicable.

1) Incus. 2) Malleus. 3) Superio incudo malleolar ligament. 4) Cog . 5) Medial attic. 6) lateral attic. 7) Surface line for internal squamo petrosal suture. 8) Posterior incudal lig.

"1" MM RULE IN TEMPORAL BONE SURGERY

THREE POINT TRIANLE

1. From tip of short process of incus to nearest point of dome of LSC It is 1.25 mm2. From dome of LSC to facial nerve It is 1.77 mm.3. From tip of short process of incus to facial nerve It is 2.36 mm.

The distance of 3 point triangle are important for otologist in1) facian nerve decompression through trans mastoidally2) facial recess approach3) in intact incus trans mastoid geniculate ganglion decompression aftre removal of incus butterss4) in tranns mastoid supra labyrinthine approach

Here the minimum distance between 3 points is 1.25 mm and the maximum distance is 2.36 mm Hence at working in this 3 tier comportant. it is better to use 1 mm bur to avoid injury to these structures

1 Tip of short process of incus 2 Dome of LSC 3 From dome of LSC to nearest point of facial nerve

1 Tip of short process of incus 2 Dome of LSC 3 From dome of LSC to nearest point of facial nerve

1 Tip of short process of incus

2 Dome of LSC

3 From dome of LSC to nearest point of facial nerve

3 mm rule

• Rule of 3 is applicable, which means anterior to posterior end of oval window is 3mm, from posterior end of oval window to anterior border of second genu of Facial Nerve is 3mm, from anterior border of second genu of Facial Nerve to apex of Arnold Triangle is 3mm.

4 mm rule

• RULE OF 4 IN TEMPORAL BONE SURGERY

Rule of 4 in temporal bone surgery is applicable to the bony labyrinth The semicircular canals bear very constant relationship to one otherThe transverse diameter of horizontal semicircular is 4 mm3) The half length of Lateral semicircular canal (from tip of incus to posterior end of LSC)is 4 mm4) The diameter of bony PSC is 4mm5) The half length of PSC is 4mm6 The diameter of bony SSC is 4 mm7) The half length of bony SSC is 4 mm 8) The arch of SSC is roughly 4 mm9 ) so 4 mm is constant landmark in bony labyrinth10) This knowledge enables surgeon to locate each canal particularly the posterior at operation using 4 mm burr as a handy measuring device

• 11) 4mm half distance of LSC 2 mm gap+4mm diameter of bony PSC total 10 mm Hence surgeon wants to skeletonise the labyrinth with out injuring the labyrinth he has to stay 10 mm away from the tip of incus along Donaldsons line downwards 11) If the surgeon drills the bone with in 10 mm of tip of incus along donoldsons line will destroy the posterior canal in sac decompression surgeries12) Hard angles and hard triangles are based on rule of 4 in temporal surgeries12) so surgeons use of 4 mm burr in labyrinthine surgery is handy and safe 14) In Temporal bone dissection subarcuate endoscopy to internal auditory canal is latest exercise The inner diameter of SSC arch is roughly 4 mm hence using 2.8 mm endoscope and following antrocerebellar canal of Chatellier surgeon can directly visualise ICA14) It is useful for surgeon to try subarcuate endoscopy, in bone dissection It is based up on rule of 4.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

5 mm rule

• RULE OF 5 Vestibule is has an anteroposterior diameter of 5 mm and superioinferior length is 5 mm hence 5 mm is reliable length in middle ear During cochlear drilling in posterior area it is advisable to use below 5 mm burr.

a, b Left ear. View of the oval window after stapes removal. Drawing showing the position of the saccule and the utricle with respect to the oval window. The saccule is occupying the major anterior portion visible

through the oval window, from a lateral to medial view.Ss: sinus subtympanicus; rw: round window; f: finiculus; su: subiculum; pr: promontory; psc: posterior

semicircular canal.

6 mm rule

•6 mm Rule - The anterioposterior length of Incus bone from IM joint to tip of the Incus is 6 mm, The distance between the tip of Incus to the tegmen is 6 mm, Surgeon while removing the bone above the tip of the incus in posterior epitympanotomy should not use more than 5 mm burr or else injury to incus or tegmen occurs with bigger burr.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

1) Incus. 2) Malleus. 3) Superio incudo malleolar ligament. 4) Cog . 5) Medial attic. 6) lateral attic. 7) Surface line for internal squamo petrosal suture. 8) Posterior incudal lig.

7 mm Rule

7 mm Rule

- The distance between the anterior commissure of oval window to vertical ICA is 7 mm in normal cellular bone.- The length of vertical ICA is 7 mm. - ICA is present anterior and inferior to oval window Hence in endoscopic transmeatal approaches to clival tumours transcochlear approaches and combained approaches to posterior fossa it is better to use below 6 mm burr and drill the bone from posterior to anterior direction and take the control of ICA If bigger burs are used in narrow anterior space surgeon may directly hit ICA. - Remember the best landmark for identification of vertical carotid is anterior commissure of oval window in normal cellular bone the distance between these two structures is 7 m mm. - The length of vertical ICA from carotid foramen to bulge of genu of ICA is 7 mm- My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

FACIAL NERVE BLOOD SUPPLY

FACIAL NERVE BLOOD SUPPLY

Dear surgeons facial nerve is supplied by two arterial system1 Labyrinthine artery branch of Iaca inturn a branch of basilar artery(vertibral systum)2 superficial petosal artery branch of middle meningeal artery inturnbranch of e c a3 stylomastod artery abranch of post auricular artery inturn abranch of eca

So vertibral external carotid arterial junction in present at facial nerve at labyrinthine segment proximal to geniculate ganglion At that point vascular supply is weak and it is called"weak spot“

At the second genu superficial petrosal and stylomastoid arteries anastomose with rich vascular supply hence it is called "Rich area“

Extrinsic vascular net work the above 3 arteries present with their venae comitantes present between periosteum and epineurium so here the stylomastoid artery along with vertical fn runs in deep bone may not be visible

Superficial petrosal artery runs along hfn at its upper border is visible clearly surgeons if u drill abone at second genu area once u reach fn area there is spouting of sentinel bleeding That is called LIGHT HOUSE SIGNVertibral system is not as robust at iac and labyrinthine part of fnThe intrisic vascular network present with in epineural sheath of nerve consists of small arterioles capillaries and venules Lymph vessels have not been identified in neural compartment

The extrensic and intrensic vascular system support the fn such that even one of the major vessel canbe ligated or nerve can be lifted from canal with out effect on fn

1 Long process of incus 2 superficial petrosal artery 3 H f n 4 pyramidal process 5 chorda 6 junction point between s p a

and stylomastoid artery 7 L s s 8 Antrum 9 Stylo mastoid artery

1 Long process of incus 2 superficial petrosal artery 3 H f n 4 pyramidal process 5 chorda 6 junction point between s p a

and stylomastoid artery 7 L s s 8 Antrum 9 Stylo mastoid artery

1 Long process of incus 2 superficial petrosal artery 3 H f n 4 pyramidal process 5 chorda 6 junction point between s p a

and stylomastoid artery 7 L s s 8 Antrum 9 Stylo mastoid artery

1 Long process of incus 2 superficial petrosal artery 3 H f n 4 pyramidal process 5 chorda 6 junction point between s p a

and stylomastoid artery 7 L s s 8 Antrum 9 Stylo mastoid artery

1 Long process of incus 2 superficial petrosal artery 3 H f n 4 pyramidal process 5 chorda 6 junction point between s p a

and stylomastoid artery 7 L s s 8 Antrum 9 Stylo mastoid artery

FIRST ventilatory pathway

• Dear surgeons Tympanic diaphragm divides the attic from mesotympanum Microscopically the diaphragm may not be visible Endoscopically tympanic diaphragm and ventilatory routes to attic are important fot functional ear surgery

There are 3 main ventilatory routes to attic 1) supra tubal recess 2) Isthmus anticus 3) Isthmus posticus

Supratubal recess is main ventilatory pathway to anterior attic Above STS anterior epitympanic recess is present tensor tympani fold seperates these two in 30% of cases there is 2nd door between these two So anterior attic directly ventilated from ET to through main door and 2nd door to anterio attic space in 70% cases the second is closed then ventilation to anterior attic space comes from isthmus anticusSurgical importance 1) in every tympanoplasty surgery surgeon should visualize these spaces any obstruction is present remove that 2) it prevents selective disventilation syndrome3) These anatomical details and removal of obstruction in these pathways prevents unnecessory mastoidectomies

1) Supra tubal recess 2) Isthmus anticus 3) Isthmus posticus 4) Long process of incus 5) Malleus 6) GATE 1 (from anterior to posterior) 7)

Horizontal tensor fold 8) Anterior attic space 9) Ventilatory route 10) Supra tensor recess 11) Tensor canal 12) Tip of malleus 13) Tegmen 14)

Eustachian tube 15) Bend of ICA

1) Supra tubal recess 2) Isthmus anticus 3) Isthmus posticus 4) Long process of incus 5) Malleus 6) GATE 1 (from anterior to posterior) 7)

Horizontal tensor fold 8) Anterior attic space 9) Ventilatory route 10) Supra tensor recess 11) Tensor canal 12) Tip of malleus 13) Tegmen 14)

Eustachian tube 15) Bend of ICA

1) Supra tubal recess 2) Isthmus anticus 3) Isthmus posticus 4) Long process of incus 5) Malleus 6) GATE 1 (from anterior to posterior) 7)

Horizontal tensor fold 8) Anterior attic space 9) Ventilatory route 10) Supra tensor recess 11) Tensor canal 12) Tip of malleus 13) Tegmen 14)

Eustachian tube 15) Bend of ICA

1) Supra tubal recess 2) Isthmus anticus 3) Isthmus posticus 4) Long process of incus 5) Malleus 6) GATE 1 (from anterior to posterior) 7)

Horizontal tensor fold 8) Anterior attic space 9) Ventilatory route 10) Supra tensor recess 11) Tensor canal 12) Tip of malleus 13) Tegmen 14)

Eustachian tube 15) Bend of ICA

1) Supra tubal recess 2) Isthmus anticus 3) Isthmus posticus 4) Long process of incus 5) Malleus 6) GATE 1 (from anterior to posterior) 7)

Horizontal tensor fold 8) Anterior attic space 9) Ventilatory route 10) Supra tensor recess 11) Tensor canal 12) Tip of malleus 13) Tegmen 14)

Eustachian tube 15) Bend of ICA

1) Supra tubal recess 2) Isthmus anticus 3) Isthmus posticus 4) Long process of incus 5) Malleus 6) GATE 1 (from anterior to posterior) 7)

Horizontal tensor fold 8) Anterior attic space 9) Ventilatory route 10) Supra tensor recess 11) Tensor canal 12) Tip of malleus 13) Tegmen 14)

Eustachian tube 15) Bend of ICA

SECOND ventilatory pathway to attic..

• SECOND ventilatory pathway to attic..It is situated between cochleariform process to long process of incus, Cog vertical tensor folds are seen anteriorly in 50% of cases, circular hole present in vertical tensor fold so ventilation passes through the mesotympanum isthmus anticus then anterior attic. Then the ear is safe ear This space is mainly occupied by body of incus (biggest ossicle u can observe incus), this space is anterior part of posterior attic, the block ofthis gate causes retraction body of incus is also main obstruction. you can visualize roof of attic clearly

• Surgical importance:1) Some surgeons say it is clearence route of attic and if is blocked, edema and granulations may be present in that area.2) Cog is surface land mark for geniculate ganglion.3) In case of attic retraction pockets surgeon can visualize this space and see the obstruction including tensor folds surgeon can excise tha fold completely4) surgeon can test the mobility of incudo malleolar joint by pressing the medial surface of incus.

1) Handle of malleus 2) Cochleariform process 3) Tensor tendon 4) Cog 5) Vertical tensor lig fold 6) Medial surface of body of incus 7) Incus 8) Tegmen tympani 9) Horizontal Facial Nerve

1) Handle of malleus 2) Cochleariform process 3) Tensor tendon 4) Cog 5) Vertical tensor lig fold 6) Medial surface of body of incus 7) Incus 8) Tegmen tympani 9) Horizontal Facial Nerve

1) Handle of malleus 2) Cochleariform process 3) Tensor tendon 4) Cog 5) Vertical tensor lig fold 6) Medial surface of body of incus 7) Incus 8) Tegmen tympani 9) Horizontal Facial Nerve

1) Handle of malleus 2) Cochleariform process 3) Tensor tendon 4) Cog 5) Vertical tensor lig fold 6) Medial surface of body of incus 7) Incus 8) Tegmen tympani 9) Horizontal Facial Nerve

THIRD VENTILATORY GATE :

• THIRD VENTILATORY GATE:Third vetilatory gate to attic is biggest gate lot of dynamic changes occur at this gate. It is present behind long process of incus and medial to posterosuperior part of TM, This gate ventilates posterior attic, auditus, antrum and mastoid. The critical structures like pyramidal process, posterior tympanic sinus, are present at the entrance of gate Gas exchange and buffering actions take place through the gate. This gate also ventilates the medial attic.

• Surgical importance:1) Blockage of this gate by edema granulations leads to retraction pockets. 2) Removal of squamosal cap is important to visualize this gate completely in functional ear surgery.3) Mastoidectomy on demand starts at this area. 4) This is main area of ventilation.5) All cells of mastoid are ventilated through this gate.

1) Long process of incus 2) Stapes 3) Stapes tendon 4) Horizontal FN 5) Lateral semicircular canal 6) Chordal crest 7) Pyramidal eminence 8)

Pyramidal crest 9) Facial sinus 10) Ponticulus 11) Posterior tympanic sinus inferior 12) Posrerior tympanic sinus superior 13) Sinus tympani 14)

Auditus 15) Antrum

1) Long process of incus 2) Stapes 3) Stapes tendon 4) Horizontal FN 5) Lateral semicircular canal 6) Chordal crest 7) Pyramidal eminence 8)

Pyramidal crest 9) Facial sinus 10) Ponticulus 11) Posterior tympanic sinus inferior 12) Posrerior tympanic sinus superior 13) Sinus tympani 14)

Auditus 15) Antrum

1) Long process of incus 2) Stapes 3) Stapes tendon 4) Horizontal FN 5) Lateral semicircular canal 6) Chordal crest 7) Pyramidal eminence 8) Pyramidal crest 9) Facial sinus 10) Ponticulus 11) Posterior tympanic sinus inferior 12) Posrerior tympanic sinus superior 13) Sinus tympani 14) Auditus 15) Antrum

1) Long process of incus 2) Stapes 3) Stapes tendon 4) Horizontal FN 5) Lateral semicircular canal 6) Chordal crest 7) Pyramidal eminence 8)

Pyramidal crest 9) Facial sinus 10) Ponticulus 11) Posterior tympanic sinus inferior 12) Posrerior tympanic sinus superior 13) Sinus tympani 14)

Auditus 15) Antrum

1) Long process of incus 2) Stapes 3) Stapes tendon 4) Horizontal FN 5) Lateral semicircular canal 6) Chordal crest 7) Pyramidal eminence 8)

Pyramidal crest 9) Facial sinus 10) Ponticulus 11) Posterior tympanic sinus inferior 12) Posrerior tympanic sinus superior 13) Sinus tympani 14)

Auditus 15) Antrum

TYMPANOPLASTY

• TYMPANOPLASTY Dear surgeons, If you are doing tympanoplasty in this type of ears then your results are very good, both functionally and in controling the discharge. Here the ventilatory pathways to attic and mastoid are very patent Please before attempting mastoids in this type of ears please look for attic ventilation. Dont do unnecessory mastoidectomies here, simply close the perforation even if the ears are wet.

1) cochleariform process 2) malleus 3) incus 4) cog 5) vertical tensor fold 6) supra tensor space 7)

Eustachian tube

1) cochleariform process 2) malleus 3) incus 4) cog 5) vertical tensor fold 6) supra tensor space 7)

Eustachian tube

1) cochleariform process 2) malleus 3) incus 4) cog 5) vertical tensor fold 6) supra tensor space 7)

Eustachian tube

1) cochleariform process 2) malleus 3) incus 4) cog 5) vertical tensor fold 6) supra tensor space 7)

Eustachian tube

1) cochleariform process 2) malleus 3) incus 4) cog 5) vertical tensor fold 6) supra tensor space 7)

Eustachian tube

COG

COG• COG -

cog.. cog.. cog.., it is familiar name for temporal bone surgeon Microscopically it may be or may not be visible clearly But endoscopically it is clear structure, a bony septum that detaches from the tegmen tympani cranially, coming down vertically towards the cochleariform process. The surgical implications of this cog are1) It is medial projection of transverse crest2) This transverse crest due to its various positions can alter the anterior attic3) If the cog is fully formed it is a constant land mark for geniculate ganglion during endoscopic approach to attic4) Cog is considered to be junction between saccus anticus and saccus medius 5 ) It represent the border between anterior epitympam and posterior epitympanum both have completely different ventilatory pathways

• 6) In 70% cases the vertical tensor fold attaches to cog sometimes the vertical tensor fold is complete or it may be partial, If the vertical tensor fold and horizontal tensor folds are complete then there is complete ventilation block for anterior attic space. 6)In above cases surgeon should completely remove cog along with tensor fold for ventilation and to prevent selective disventilation syndrome. 7) In some cases vertical tensor fold attaches in front of cog not to the cog, There is small space between cog and above ligament, that small place in front of cog is Lurking space for cholesteatomas in those cases surgeon has to look for the space for clearance of disease. 8) Supralabyrinthine space is situated between superior semicircular canal posteriorly, facial nerve anteroinferiorly and tegmen superiorly. Cog divides this space into two. In supralabyrinthine space cholesteatomas cog has to be drilled completely for removal of the disease. 9) cog is roughly indicates the Fisch plane(meatal plane). 10) Cog is rough land mark for IAC on medial side.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

ANTERIOR PART OF POSTERIOR ATTIC - ROOT ENTRY FOR PETROUS APEX

ANTERIOR PART OF POSTERIOR ATTIC ROOT ENTRY FOR PETROUS APEX• Anterior part of posterior medial attic is a surgical space, it has

a important surgical implication. it is bounded superiorly by tegmen anteriorly by cog inferiorly by isthmus anticus medially by supralabyrinthine space laterally by ossicular heads posteriorly it is freely communicates with posterior medial atticThe latero medial diameter is 1.8 mm and antero posterior lengh is 4mm

Microscopically it is not visible through the ear unless surgeon performs atticotomy and removal of ossicles With 45 degree endoscope visualising through isthmus anticus this space is clearly seen.

The surgical implications of this space are• 1 for complete removal of cholesteatomas in attic

space2 for drilling of cog 3 for the perforation of vertical tensor folds in selective disventilation syndromes4 for supra labyrinhine approach to petrous apex5 for decompression of geniculate ganglion6 for transmeatal exposure of mid fossaà7 Rarely for cutting tensor tendon in clik tinnitus8 For excison of malleolar head9 In tubotomies and tuboplasties

Endoscopic ear surgeons should look in to this space routinely to get more details of attic Microscopically this space is not visible, Clear visualisation of this space endoscopically leads to new approaches in future in functional endoscopic ear surgery

• 1 tegmen 2 cog 3 vertical tensor fold 4 tensòr tendon 5 prussaks space 6 handle of malleus 7 supratubal space

HYPOTYMPANUM

• It is unfortunately most neglected portion for ENT and skull base surgeons. Hypotympanum is a part of tympanum below the floor of external auditory canal, extending anteriorly from Carotid canal to styloid apparatus posteriorly, the floor is dome shaped with concavity facing downwards The depth of Hypotympanum is variable from 1 mm to 6 mm The anteroposterior distance is 10mm and mediolaterally it is 4 mm. The surgical implications of Hypotympanum are1) Though it is root entry for major vessels it is neglected part2) It is more variable in depth, surgeon should be careful while entering this cavity 3) Normally Hypotympanum is occupied by trabeculi of variable heights usually they are 7 to 9mm, the anterior long one is called trabeculi longa where as posterior long one is called trabeculi profunda. 4) Some times in Hypotympanum the whole trabeculi are absent. The floor or jugular wall or pavementum pyramidalis raises up to cochlear capsule.

• 5) The nature of Hypotympanum tells the surgeon the type of temporal bone. 6) After opening the Hypotympanum if the trabeculi present surgeon is safe because the jugular dome is 6 mm in deep and sigmoid sinus is posterior. 7) High jugular bulb is associated with anteriorly placed sigmoid sinus where translabyrinthine and intact fallopian bridge techniques are very difficult. 8) With high jugular bulb touching cochlear capsule infra cochlear approach to petrous apex is impossible

• 9) The pneumatic cells opens into Hypotympanum extends into infratubal pneumatic track towards apex of pyramid in the disease process surgeon has to carefully follow the track to remove disease completely. 10) In 24% cases bony cavity or anterior hypotympanic sinus is present in front of the Hypotympanum at the junction of inner and outer walls

• 11) Anterior hypotympanic sinus common area of Lurking cholesteatomas With endoscopic approach surgeon can remove the disease. 12) Finiculus or sustantaculum is a bony crest connecting the postis anticus (anterior lip ) of round window to hypotympanum. It is an important land mark.13) Under the cochlear capsule and finiculus there is deep tunnel passes under the ICA to reach petrous apex it is called sub cochlear tunnel (tunnel of promontory). usually it is present common pathway for extension of cholesteatoma is through this tunnel Microscopically this tunnel is not visible endoscopically we can remove the disease from this tunnel. 14) in 16% cases the bony jugular wall is dehiscent surgeon should be very careful while elevating or removing the disease 15) Jugulo carotid septum present between ICA and jugular bulb present in hypotympanum. Erosion of crotch is characteristic sign of glomus jugulare tumours.

• 16) "Artery of trouble", inferior tympanic artery a branch of ascending pharyngeal artery along with Jacobson's nerve passes through the crotch. The Ascending pharyngeal artery is smallest branch of external carotid in glomus it is the main arterial blood supply gives lot of trouble to surgeon hence Henly named it "Artery of trouble" 17) Finiculus is rough surface land mark for Jacobson's nerve and inferior tympanic artery in Hypotympanum.18) Brackmans triangle is present in hypotympanum The base of the triangle is formed by base of cochlear capsule the anterior limb is formed by ICA the posterior limb is by jugular bulb, It is common route of infracochlear approach for petrous apex. 19) Endoscopically subtympanic sinus is divided from hypotympanum by finiculus. 20) Erosion of outer tympanic wall of hypotympanum leaving annulus intact occur in keratosiscalled "Hanging rope sign" So surgeons Hypotympanum is such important structure during temporal bone dissections we do not dissect this part routinely but endoscopically we can observe clear anatomy of this part.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

SUPRATUBAL RECESS ANTERIOR ATTIC SPACE

SUPRATUBAL RECESS ANTERIOR ATTIC SPACE

Supratubal space and anterior attic space are commonly heard spaces in cholesteatoma surgery Microscopically these spaces may not be clearly visible. These two places are very important for functional otological surgeon Supratubal space is upper part of protympanum Anterior attic space is space above the supratubal space in front of malleus These two spaces develop from saccus anticus and posterior attic space space develop from saccus medius

SURGICAL IMPLICATIONS

1) Endoscopic functional otological surgeon should know detailed anatomy of these spaces in order to perform complete functional surgery2) Ligaments are connective tissue bands and ligamental mucosal folds are two approximated mucosal surfaces with space connective tissue fibres LML, AML, PML and PIL are ligaments where as tensor folds and lateral incudo malleolar folds are ligamental mucosal folds3) horizontal tensor fold separates the supra tubal space to anterior attic space In 70% of cases it totally separates STS to anterior attic space In this type the ventilation of anterior attic is from isthmus anticus

• 4) In 30%of cases the horizontal tensor fold has perforation through which supratubal space communicates with anterior attic space5) Vertical tensor space is attaches to cog or some times anterior to it separates anterior attic space to posterior attic space6) If any granulations edema or cholesteatoma blocks the isthmi or air pathways in tensor folds that will lead to retractions dis ventilation finally cholesteatomas7) The size and position of supratubal space and anterior attic space is variable and depends up on the horizontal tensor fold if the fold is horizontal the supratubal space is shallow and if the horizontal tensor fold is oblique the supratubal space is deep

• 8 ) Vertical tensor fold may be complete or partial9) The common places of presence of cholesteatoma in middle ear cleft are sinus tympani anterior attic recess and hypotympanic sinus10) Anterior atticotomy is a surgical procedure in which opening of anterior attic space to remove the cholesteatoma with microscope11) with an endoscope endoscopic surgeon should remove the disease and Re-establish the ventilation of these places, It is functional otologic surgery12) supratubal space and anterior attic have smooth walls where as posterior attic is having bony excretions That is differentiating point.

• 13) At the entrance of supra tubal recess tensor canal is protruding landmark14) some times supratubal recess is communicated with peri carotid and peri tubal cells Surgeon should be careful while removing disease at that area.15) Rarely 1st genu of ICA reaches upto supratubal recess surgeon should be very careful at these situations16) The relation between CAL (chorda tympani, anterior tympanic artery and anterior malleolar ligament) and supratubal recess should be familiar to surgeon while doing anterior tympanotomy of MorimutsueDuring microscopic temporal bone dissection courses no surgeon showed me these spaces. Endoscopically everything is shown clearly. Hence for cholesteatoma surgeons these spaces are very important to better understanding of ventilation and disease and its removal. My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

UPPER RETROTYMPANUM

• This is endoscopic view of upper retrotympanum, here elevations and depressions are present, sometimes absent or may be partially present. - Like the Cochleariform process in mesotympanum, Finiculus in Hypotympanum, here in the Retrotympanum, the Piramidal eminence is the reference point. - The Pyramidal eminence , chordal eminence and styloid eminence are the important eminences. 1) Pyramidal eminence - from this three crests arise which divide the upper retrotympanum into 4 compartments.2) Chordal eminence - it is the prominence from which the chorda comes out from posterior wall.3) Styloid eminence - A bony prominence of posterior wall at the level of sibiculum. 4) Chordal crest - It is vertical crest connecting chordal eminence to Pyramidal eminences 5) Pyramidal crest - crest between Pyramidal eminence and styloid eminence 6) Ponticulus - It is present between Pyramidal eminence and posterior part of promontory 7) Sibiculum - present between postis posticus of round window and Retrotympanum.

• LATERAL COMPARTMENTIt is present between chorda tympani and FN A) Facial sinus - is between chorda and FN above chordal crestB) Fossula of Grivot - is between Pyramidal eminence and chorda below chordal crest.

• MEDIAL COMPARTMENT A) Sinus Tympani- It is present between Ponticulus and Sibiculum.B) Posterior Tympanic Sinus of Proctor- It is present between Facial Nerve and Ponticulus and it is divided into Posterior Tympanic Sinus Inferior and Superior by Stapedial Tendon.C) Subpyramidal Sinus- It is present under the Pyramidal Eminence.Cholesteatoma present in Sinus Tympani extends to Posterior Tympanic Sinus through Subpyramidal Sinus into Isthumus Posticus finally Aditus, Antrum and Mastoid.These compartments are important for endoscopic cholesteatoma surgeon Majority of these compartments can be visualized with 45 degree endoscope sitting in front of the patient

• Dear surgeons appreciate the above surgical anatomy to appreciate the following surgical implications 1) Sinus Tympani is common site of Cholesteatoma Type A ,Type B, which is approachable through endoscope,Type C is approached through Arnold Triangle.2) Fossule of Grivot is present in 50 percent cases, it is nidus for Cholesteatoma, it is 1 mm in diameter.3) Rules of 1,2,3,4,5,6,7,8,9,10 mm are applicable for temporal bone dissection.4) Rule of 3 is applicable, which means anterior to posterior end of oval window is 3mm, from posterior end of oval window to anterior border of second genu of Facial Nerve is 3mm, from anterior border of second genu of Facial Nerve to apex of Arnold Triangle is 3mm.5) Common site of Lurking Cholesteatoma is Sinus Tympani and Subpyramidal Sinus6) FN passes posterio lateral to Pyramidal eminence, too deep drilling is dangerous at this region7) Stapes muscle is 7mm in length and it originates from Pyramidal ridge not Pyramidal eminence 8) Gentle curettage of posterior meatal wall is necessary to visualise retrotympanum properly 9) Fustis is resistant to cholesteatoma destruction, hence it does not allow cholesteatoma to go down.10) We can see "muscle of musician" (The Stapedius) here Facial nerve supplies this muscle passes underneath the muscle

• 11) ampulla of posterior semicircular canal is present at the floor of sinus tympani hence deep curettage leads to injury it, leading to SN hearing loss. 12) while removing cholesteatoma here the direction of movements of instruments is posterior to anterior to prevent subluxation of stapes.13) Anterior tympanum is meso and protympanum mainly compared to nose serves cleaning where as posterior tympanum as attic antrum and mastoid compared as a lung serves as gas exchange and buffering action. 14) Isthmus posticus situated between long process of incus and posterior incudal ligament mainly serves as a ventilation to key area, Isthmus posticus serves mainly as a clearing area. 15) sibiculum divides retro tympanum in to upper and lower compartments. 16) lower retrotympanum acts as prechamber for sound out flow.Every cholesteatoma surgeon should be familiar with this anatomy Microscopically we may not see these, For residents this anatomy with excellent pictures are very useful. My special thanks to prof presuitti, prof Marchioni and prof Jao Flavio Nogueira who taught me all these things.

it is endoscopy with 45 degrees through posterior isthmus with intact incus 1 . Horizontal f n 2. l s s

3 .auditus 4. antrum 5. long process of incus

SUB PYRAMIDAL SINUS AN IGNORED SPACE :

• SUB PYRAMIDAL SINUS AN IGNORED SPACE :Subpyramidal space unknown, but very important space in retro tympanum it is present under the pyramidal spaceIt is bounded:Larerally by pyramidal processMedially by vestibuleInferiorly by ponticulusSuperiorly leading in to posterior tympanic sinus superiaris of Proctor.Posteriorly by 2nd turn of FNAnteriorly by posterior tympanic sinus inferiorMicroscopically this space ia not visible clearlySurgical importance 1) in 8 % of sinus cholesteatomas this space is involved2) sinus cholesteatoma is extended to antrum through space and posterior tympanic sinus to enter antrum it passes medial to body of incus 3) attic cholesteatoma extends to antrum through posterio pouch of von troltch passes lareral to incus4) second genu of FN is 3.5 mm posterior to pyramidal tip while curetting pyramid to enter the space for removal of cholesteatoma surgeon should not curette too posterior and prevent damage to FN5) In transcanal labyrinthectomy the posterio part of vestibule is entered through this space6) sinus tympani sub pyramidal sinus posterior tympanic sinus are present in a row in retro tympanum To prevent recurrence surgeon should know thouroughly these spaces in cholesteatoma surgery7) some times pyramidal bridge present between pyramid and superior gives subpyramidal sinus pathway.

1 pyramidal process 2 stapes tendon 3 stapes 4 ponticulus 5 sibiculumm 6 sinus tympani

7 sub pyramidal sinus 8 round window

1 pyramidal process 2 stapes tendon 3 stapes 4 ponticulus 5 sibiculumm 6 sinus tympani

7 sub pyramidal sinus 8 round window

1 pyramidal process 2 stapes tendon 3 stapes 4 ponticulus 5 sibiculumm 6 sinus tympani

7 sub pyramidal sinus 8 round window

1 pyramidal process 2 stapes tendon 3 stapes 4 ponticulus 5 sibiculumm 6 sinus tympani

7 sub pyramidal sinus 8 round window

1 pyramidal process 2 stapes tendon 3 stapes 4 ponticulus 5 sibiculumm 6 sinus tympani

7 sub pyramidal sinus 8 round window

COCHLEARIFORM PROCESS

• COCHLEARIFORM PROCESS

Dear sirs, It is spoon shaped bony process present over medial wall of middle ear Its surgical implications are 1) it is most resistant part for cholesteatoma bony erosion, hence it is visible even in massive erosion by disease, a land mark 2) Tensor muscle hooks round it to form tendon and forms anterior boundary of isthmus anticus 3) from here tensor muscle passes anteriorly to eustachian tube, hence forms land mark in tubotomy 4) from here FN takes "7" degree up to form pre cochleariform part 5) Jocobson nerve passes vertically down wards it is useful in Jocobson's neurectomy 6) COG or transverse crest is roughly present at this level

• 7) vertical tensor fold attaches to this its perforation is necessory in selective dis ventilation syndrome 7) At this level basal turn of cochlea ends and second turn starts 8) 4 to 5 mm below this cochlear nerve from IAC enters modiolus, a good land mark for trans cochlear surgery 9) Bills bar exactly situated at fundus of IAC at this level on medial side, a good land mark in inner ear surgery 10) plesters 3 rd window is made 1 .5 mm below its posterior edge as cochleatomy and piston insertion in cases of obliterative otosclerosis with unidentifiable windows 11) From its posterior edge BAST crest arises attaches to facial canal it is remnant of stapedial artery gives support to facial canal 12) It is approximate level of anterior wall of vestibule so 1st part of FN passes anterior to it.

PRE COCHLEARIFORM PART OF HORIZONTAL FACIAL NERVE (HFN)

PRE COCHLEARIFORM PART OF HORIZONTAL FACIAL NERVE (HFN)• Surgical Implications -• 1) It is present between geniculate ganglion up to cochleariform process usually 3

to 5 mm in length It is separated from 1st part by geniculate gutter, this part of nerve passes through deep gutter Laterally it is covered by supralabyrinthine and perigeniculate cells of 3 to 5 mm thickness. cochleariform process is useful landmark 5 mm of bone separates between it and 1st part2) Anterior epitympanic recess is useful landmark for identification of this part of nerve. 3) Removal of malleus is necessary for skeletonising this part of nerve4)The continuity of direction of this part anteriorly is greater superficial petrosal nerve through foramen of Henli. 5) Excessive curetting of bone and deep drilling of bone in anterior attic space endangers this nerve damage in cholesteatoma surgery. 6) Supra labyrinthine space is situated between it anteroinferiorly and SSC posteriorly tegmen at roof a common route for supralabyrinthine approach to petrous apex. 7)The angle between this part and labyrinthine part is 70 degrees Once surgeon looks at this laterally these two parts are superimposed.

• 8) GENICULATE GANGLION -It is bluish pink in colour because of its rich blood supply-It is usually covered by fairly thick segment of bone, sometimes it may be covered by thin sheath or sometimes this sheath may also be absent -It lacks bony covering in 15% of cases so it is vulnerable to injuries during surgery especially in Mid fossa approach -The arachnoid piamater extends up to Geniculate ganglion so this area of Facial nerve is primary site for cholesteatoma, vascular malformations, meningiomas and schwannomas. -The proximal (pre Cochleariform ) segment is 3 to 5 mm in length

• 9) FISH IN POND APPEARANCE At the mastoid part the Facial nerve is deep in the bone like a fish in pond, at the post Cochleariform of Horizontal Facial Nerve the fish comes to the surface of water and the Facial nerve appears as a prominent structureThe fish again goes deep into the pond where the Facial nerve deep inside the fallopian canal at the 1'st part and at the IAC.

• 10) "1 MM RULE" IN TEMPORAL BONEusually 1mm of bone separates between Horizontal facial nerve and foot plate facial nerve and lateral semi circular canal and facial nerve and vestibule at the anterior part of foot plate. Hence facial nerve passes through narrow space surrounded by important structures thus prolapse of nerve occurs laterally towards middle ear side Here the diameter of FN is 1.5 to 2 mm here at mid horizontal FN, but the available space is 1 mm (1mm rule), so nerve prolapse occurs at this part so rule of 1 applicable to facial nerve here.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

POST COCHLEARIFORM SEGMENT OF HORIZONTAL FACIAL NERVE

POST COCHLEARIFORM SEGMENT OF HORIZONTAL FACIAL NERVE

• 1) It is often clearly visible paricularly after removal of incus to Otosurgeon2) It is 6 mm in length and 1.75 mm in diameter, Here often there is dehiscence of fallopian canal and often the nerve prolapse towards oval window 3) According to Fisch and Yanagihara there are two areas of marked narrowing of facial canal in adults A) at meatal foramenB) at mid tympanic region Remember if the narrowing above the oval window it is not pathological4) This segment is situated between BAST crest and pyramidal crest These two crests holds the nerve firmly5) Gurriors Line of 3 ridges The lower border line this part of FN corresponds to vestibular crest of medial wall of vestibule and in turn corresponds to transverse crest of fundus of IAC, All three are at same level This is good land mark for surgeon in transmeatal opening of IAC 6) Anterior ends of LSC and FN are parellel 1 mm seperates between two where as at posterior end of foot plate FN is little far away from LSC 2 mm of bone seperates between two7) At anterior end of foot plate FN is close to vestibule 1 mm of bone seperates between two where as at posterior end of footplate vestibule directs medially and 2.5 mm of bone seperates between these two

8) Rule of 3 The distance between anterior and posterior ends of foot plate is 3 mm, The distance between posterior commissure of foot plate and the anterior border of 2nd genu of FN is 3mm finally the distance between 2nd genu to apex of Arnold triangle is 3 mm. 9) Barber poling drilling important for FN decompression vertical FN should be drilled from posterior side of nerve at 2nd genu on lateral side where as on tympanic side it is drilled from inferior side of nerve to decompress FN10) At 2nd genu area the FN is vulnerable to injury during mastoid surgery11) In middle portion the HFN runs over the oval window forming the roof of the posterior tympanic sinus of Proctor this is common area of injury in cholesteatoma. 12) The second segment of FN is linked to mastoid part not by angle but by curve Fossa incudis is present superior to this. Inferiorly inferior Schwalbe sinus present 13) From distal part of HFN the nerve enters the wall of GALLE 14) The distance between the 2nd genu to LSC is 1.77 mm the distance between tip of incus to LSC is 1.25 mm, where as the tip of incus to 2nd genu is 2.36mm. These three points forms facial triangle while drilling bone near the 2 genu these measurements are important for safe drilling.15) Pyramidal Triangle - It is the small triangular bone between distal horizontal facial nerve and Pyramid, the base of the triangle is formed by fallopian crest The apex is situated towards posterior The length of triangle is 3 mm Hence at the apex of the triangle at 3 mm posterior to pyramidal process the FN turns to become 2nd genu It is surgically important, while endoscopic transmeatal decompression of the nerve.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

STYLOID COMPLEX IS IT NEGLECTED?

Especially for - intact fallopian bridge technique for glomous jugulare

surgery

• STYLOID COMPLEX IS IT NEGLECTED?• Styloid complex bone is present between tympanic and

labyrinthine walls of inferior retro tympanum. Microscopically this region is not clearly visible, styloid complex is of 2nd arch origin including facial nerve Styloid complex is composed of1) styloid eminence from retro tympanum towards sibiculum2) styloid peg it is tympanic part of styloid process3) styloid button- round button medial to styloid eminence may be present or may not be, If it is present it indicates good retro facial cellular tract.Vertical facial nerve is present behind styloid complex jugular bulb is always medial to it may be very close or 1.2 cm apart to this Observe these pics the cross point of styloid ridge and pyramidal ridge from the point vertical FN is 5 mm posterior.

• Surgical importance: endoscopic endomeatal skull base surgeon should be thoroughly familier with styloid complex area1)Idetification ofstyloid complex facilitate the faster and safer exposure of FN endoscopic endomeatally2) styloid button indicates presence of good retro facial cell tract3) styloid peg is tympanic portion of styloid process In tranmeatal skull Base surgery it is good land mark4) In intact fallopian bridge technique for glomous jugulare surgery identification of FN and drilling of styloid complex is most important5) Above the styloid complex middle retro tympanum is hosting chamber for cholesteatomas.Hence dear endoscopic ear surgeons please visualise this neglected but very important part routenely while you are performing EES In future it may give important endoscopic route to skullBase surgery

1) styloid eminence 2) pyramidal process 3) pyramidal eminence 4) jugular bulb 5) styloid peg 6) otosclerotic triangle ( fossula anti

fenestrae) 7) posterior malleolar ligament 8) styloid ridge 9) pyramidal ridge 10) styloid button

1) styloid eminence 2) pyramidal process 3) pyramidal eminence 4) jugular bulb 5) styloid peg 6) otosclerotic triangle

( fossula anti fenestrae) 7) posterior malleolar ligament 8) styloid ridge 9) pyramidal ridge 10) styloid button

1) styloid eminence 2) pyramidal process 3) pyramidal eminence 4) jugular bulb 5) styloid peg 6) otosclerotic triangle

( fossula anti fenestrae) 7) posterior malleolar ligament 8) styloid ridge 9) pyramidal ridge 10) styloid button

1) styloid eminence 2) pyramidal process 3) pyramidal eminence 4) jugular bulb 5) styloid peg 6) otosclerotic triangle

( fossula anti fenestrae) 7) posterior malleolar ligament 8) styloid ridge 9) pyramidal ridge 10) styloid button

1) styloid eminence 2) pyramidal process 3) pyramidal eminence 4) jugular bulb 5) styloid peg 6) otosclerotic triangle

( fossula anti fenestrae) 7) posterior malleolar ligament 8) styloid ridge 9) pyramidal ridge 10) styloid button

1) styloid eminence 2) pyramidal process 3) pyramidal eminence 4) jugular bulb 5) styloid peg 6) otosclerotic triangle

( fossula anti fenestrae) 7) posterior malleolar ligament 8) styloid ridge 9) pyramidal ridge 10) styloid button

FURGUSON'S SQUARE

FURGUSON'S SQUAREThis is superiorly formed by facial nerve inferiorly formed by stapes tendon posterior boundary is upper lip of pyramidal process and anterior boundary is long process of incus Its content is posterior crus of stapes Microscopically it may not be much appreciable, But endoscopically it is clearly seen Now a days we are doing endoscopic reverse position stapes surgery that means we sit in front of patient and do surgery by Victor Goodhil method, most of the ear pathologies are present in posterior part of tympanum If u sit anteriorly u r target is straight in front of u then the surgery is easy. Furgusons square is clearly visible in reverse position The advantages of this position are1) we can visualise posterior part of foot plate with out much bone curette and without removing posterior crus and stapes tendon 2) we can see pathology in retrotympanum with "0" degree scope 3) we can visualise posterior tympanic sinus of proctor for cholesteatomas

• 4) endoscopic trans meatal facial nerve decompression 5) mainly to see posterior stapedio vestibular ligament in otosclerosis (now a days the degree of deafness in otosclerosisis due amount of fixation of that lig)6) posterior meatal wall, stepes tendon and posterior crus do not come in to way during stapes surgery. Microscopically surgeon sits infront of patient and do operation is difficult but endoscopically it is easy, keep in mind our target area is straight in front of us rather than in our stomach surgeons please try and see how easy the stapes surgery is..7) with this Plesters antrotomy and antral control to check and type 1 2 3 atticotomies procedures are easy8) Removal of squomosal cap of Isthmus posticus and follow the disease towards auditus and antrum without extensive mastiodectomies is possible..

POSTERIOR EPITYMPANOTOMY (ATTICO TYMPANATOMY) SURGICAL IMPLICATIONS

• POSTERIOR EPITYMPANOTOMY (ATTICO TYMPANATOMY) SURGICAL IMPLICATIONS

• Dear surgeons, posterior epitympanotomy is 2nd excerise in temporal bone dissection lot of clinical implications are attributed to this space1) Rule of "6" - The distance between the tip of incus to tegmen is 6 mm, Hence surgeon should not use bigger burs than 6 mm while drilling this area The drilling should be medial to lateral direction2) Rule of "7" - The length of incus from tip of incus to lncudo malleolar lig is 7 mm. It is useful measurement while performing mini sub temporal approach3) The lateral attic is situated between ossicles and scutum of Leidy is narrow space measuring about 0.6 mm, Hence it is not advisable to probe in this space with bigger probes.4) Upper part of lateral attic, superior attic, and medial attic is called superior attic This space is clear in this approach5) Axis of rotation of ossicles passes from posterior incudal lig to anterior malleolar lig, Hence subluxation of incus causes up to 25 db hearing loss as occurs in stapedectomy.

• 6) Supratubal recess and anterior attic space is not seen through procedure with intact ossicles. hence surgeon should search for above spaces through endomeatal route with intact ossicles.7) Superior lncudo malleolar ligament is clearily seen through this procedure is land mark for internal squamo tympanic suture, a good land mark in mid fossa surgery.8) Internal petro squamosal venous sinus or LAKE OF LUSCA runs along the above suture which connects sigmoid sinus to middle meningeal vein, some times in adults it persists because of profuse bleeding while seperating dura from tegmen in mid fossa.

• 9) Vein of ENGLISH is a vein connects lake of lusca to sigmoid sinus in majority cases. If vein of english is present, it opens into sigmoid sinus above vein of Santorini. surgeons should not confuse it for Labbes vein as it opens in to transverse sinus posteriorly, if vein of English is present it looks like a bluish thread through intact thin tegmen in this procedure.10) In posterior part of attic, tegmen is high where as in anterior part of attic tegmen slops down to join tensor canal . Here the rule of "1" is applicable.11) Supra labyrinthine space present between superior semicircular canal and HFN lies anterior to incus, it is good route for petrus apex.

• Hence residents, while performing posterior epitympanotomy please observe above points to get good knowledge of temporal bone

1) Incus. 2) Malleus. 3) Superio incudo malleolar ligament. 4) Cog . 5) Medial attic. 6) lateral attic. 7) Surface line for

internal squamo petrosal suture. 8) Posterior incudal lig.

1) Incus. 2) Malleus. 3) Superio incudo malleolar ligament. 4) Cog . 5) Medial attic. 6) lateral attic. 7) Surface line for internal squamo petrosal suture. 8) Posterior incudal lig.

1) Incus. 2) Malleus. 3) Superio incudo malleolar ligament. 4) Cog . 5) Medial attic. 6) lateral attic. 7) Surface line for internal squamo petrosal suture. 8) Posterior incudal lig.

1) Incus. 2) Malleus. 3) Superio incudo malleolar ligament. 4) Cog . 5) Medial attic. 6) lateral attic. 7) Surface line for

internal squamo petrosal suture. 8) Posterior incudal lig.

1) Incus. 2) Malleus. 3) Superio incudo malleolar ligament. 4) Cog . 5) Medial attic. 6) lateral attic. 7) Surface line for

internal squamo petrosal suture. 8) Posterior incudal lig.

FUSTIS

FUSTIS•

it is fustis a solid bony column connecting the retrotympanum to round window niche. So far this structure is neglected Microscopically it may not be clearly visible, but endoscopically it is seen clearly The surgical implications of this structure are 1) its origin is pylogenically different from other parts of that area hence it behaves differently 2) It contains enzymes which are resistant to cholesteatoma destruction 3) it prevents sinus cholesteatoma extending downwards..4) This structure is directed towards round window, in narrow round window niche by following its upper border, we can identify the round window membrane 5) It divides upper part of subtympanic sinus, concomerata into medialis and lateralis. C medialis is site for posterior ampullary nerve section. 6) Fustis regulates smooth out flow of sound waves from round window membrane.

• 7) It helps in creation of pressure difference between round and oval windows encourages acoustic coupling. 8) It gives support round window niche because both postis anticus and postis posticus contains cochlea and subcochlear portion that are hollow structures. 9) This structure modulates according to round window niche i. e, "V" shaped, square shaped, triangular gothic shaped, like that, to have a relation with RW10) In absent sibiculum, the fustis gives support.11) Fustis narrows the round window niche there by protects the round window membrane (rupture)normally. 12) embryologically fustis develops between periosteal layer of the labyrinthine capsule and the thin smooth plate of Pavementum Pyramidalis and it is ontogenically important structure. So surgeons, fustis is very important structure at outflow gate of sound in middle ear. In 1968 Bruce Proctor mentioned, Recently prof Presutti, Prof Marchioni and Prof Joao F Nogueira described this part. so surgeons please look this important but poor part while performing surgeries because it is present in all middle ears..

Round window

• So far round window is neglected part in middle ear Now a days it is gaining popularity For type4 and 5 t plasties sono inversion techniques viroplasties gentamycin and other chemical perfusions cochlear implant insertions corticosteroid perfusions in s n d skullbase approaches round window is important There are so many verieties of shapes of r w s I have previously discussed 4 types of r w s

" High arched" round window

" High arched" round window• Dear surgeons it is" High arched" round window it is

present 1-3%of cases you can compare this window to normal r w which is shown here The arched round window associated with1 compressed cochlear capsule in caratico facial angle2 Deep hypotympanum3 long trabiculae including trabicula longa4 wide concomerata lateralis and absent concomireta medialisWide postis posticus with subcochlear tunnel5 wide sinus tympani

"PARABOLIC" round window

"PARABOLIC" round window

• Dear surgeons it is "PARABOLIC" round window in shape present 1% of cases characterised by 1 two vertical limbs longer than tegmen2 wide niche3 Third limb is formed by styloid complex4 s shaped cochlea including sub vestibular portion5 wide finiculus with high pavementum pyramidalis6 deep carotid recess7 3rd part of facial nerve is nearer to middle ear

• Surgical implications1 wide angle cochlea hence cochlear implant electrode insertion is easy2 narrow vestbular window stapes surgery is difficult3 endoscopic endomeatal f n decompression is easy in these cases4 vibroplasty is easy5 infracochlear approach to petrous apex is not possible in this type of round windows6 endoscopic endomeatal approach to IAC is easy in this type of cases7 s shaped cochlea here allows wide transcochlear approach to clivus

COCHLEA

• Hi, this is human cochlea, I did it in Fortaliza, Brazil with help of prof Jao flavio Nogueria, 3 years back it is endoscopic dissected specimen Its base is situated between two windows, - Remember its apex is directed towards carotid facial angle you should know the course of horizontal FN and greater petrosal nerve which passes through facial hiatus (Henli's foramen) - The internal carotid artery is usually situated 7.5 mm anterior to anterior end of foot plate, if you want it drill cochlea anterior to foot plate please use 5 mm bur not more than that in trans cochlear approach - geniculate ganglion situated over apex of cochlea. - labyrinthine part of facial nerve passes over the roof of 2nd and basal turns in parisier's triangle. - The thickness of cochlear wall is 1 mm to 1.5 mm over promontory Hence it is advisable not to use monopolar cautery over promontory. - In sclerotic mastoids the cochlea close hug the ICA But in cellular mastoids there is gap between ICA and cochlea hence in endoscopic transcochlear approach to clivus it is better to leave anterior turn of cochlea particularly in sclerotic mastoids. - cochlea is under tensor tympani muscle in tubotomy procedure after removal of tensor muscle- please do not drill the medial wall of tensor canal wall as there is 1 mm bone separates it from cochlea. These arer few anatomy and surgical implications of cochlea Any more advise me..

VESTIBULE

• VESTIBULEVestibule is central part of labyrinth measuring about 5×5 mm anterio posterior and superio inferior. The depth of cavity is 2 mm at periphery and 3 mm at centre and belowsurgical implications. 1) The deepest portion of cavity is at its centre and below 3mm hence piston should be inserted at this level2) LINE OF 3 RIDGES OF GURRIER The lower border of HFN is at level of vestibular crest and it turn corresponds to level of transverse crest on fundus level It is important land mark in endoscopic transmeatal opening of IAC. 3) Anteriorly saccule is closure to lateral surface perilymphatic fibres attaches between saccule and foot plate here piston should not be placed here

• 4) Utricle is horizontally placed structure where as saccule is vertically placed on medial wall5 ) utricle is placed at the level of HFN hence in transfoot plate cochlea destruction angled hook is used. 6) Vestibular pyramid is small bony projection present on anterior part of vestibular crest contains terminal fibres of utricular nerve7) Posterior recess is deep recess present posteriorly in vestibule in which crus commune and ampulla of PSC opens in to.

• 8) Cochlear recess is a small recess present behind vertical vestibular crest, inferiorly it lodges beginning of ductus cochlearis. 9) RIECHERTS SPOT - small cribriform area present at inferior part of cochlear recess though nerve filaments go to initial portion of vestibular portion cochlea these are nerve filaments of BECHTEREW it has to be destructed in labyrinthectomy. 8) At floor of vestibule origin of osseous spiral lamina and vestibulo tympanic fissures present, these parts are important for cochlear implant surgeon9) Mouth of scala vestibuli is present at the antero inferior part of oval window In total stapectomy surgeon should not disturb this area.

• 10) Sulciform gutter a small groove present behind utricular recess in which the endolymphatic duct opens in to vestibule During labyrinthine surgeries this area should be safeguarded. 11) The inferior level of vestibule present 1 mm below oval window anterior level is at anterior level of oval window superior level of vestibule is at ampulla of LSC where as the posterior level of vestibule present 3mm posterior to oval window hence 3 mm hook is necessary to destruct labyrinth through oval window.

RULE OF 5 Vestibule is has an anteroposterior diameter of 5 mm and superioinferior length is 5 mm hence 5 mm is reliable length in middle ear During cochlear drilling in posterior area it is advisable to use below 5 mm burr.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy.

PARISIER'S TRIANGLE (DANGEROUS TRIANGLE)

PARISIER'S TRIANGLE (DANGEROUS TRIANGLE)

Perisier's triangle is very important triangle in endoscopic ear surgery1) Superior limb is formed by inferior part of HFN 2) The apex is formed by the geniculate ganglion

3) The base is formed by the anterior commissure (end) of oval window 4) Inferior limb is formed by tunning point of jocobson's nerve to the the

geniculate ganglion.

• The surgical implications are

1) This triangle contains labyrinthine part of FN. 2) During transotic or transcochlear approaches surgeon should respect this triangle and drill carefully to avoid injury to FN. 3) Clinically labyrinthine part consists of two segments a meatal segment of nerve, labyrinthine part of nerve. total length of this nerve is 3 to 5 mm. Anteriorly we can see these parts clearly through this triangle. 4) 1st part of FN passes close to lower border of precochlear HFN towards anterior end of oval window in this triangle. 5) Irregular drilling of cochlea in this triangle damages FN That is why it is called DANGERS TRIANGLE. 6) During trans meatal endoscopic dissection of IAC, this triangle important for identification of nerves7) Translabyrinthine approach visualises posterior surface of 1st part of FN, in transcochlear approaches the anterior surface of the nerve is exposed. In transottic approaches 270 to 320 degrees of 1 st part of FN is exposed. 8)Observe closely the labyrinthine part of FN there is a constriction of labyrinthine segment and meatal segment. Facial nerve key points1) Facial nerve changes direction 5 times during its course from brain stem to styloid foramen. 2) No other nerve in body covers such a long distance in bony canal3) facial nerve contains 10000 axons that are responsible for the innervation of the face musculature and also for the communications with other nerves human body4) work with injured facial nerve requires lot of patience.

• RULE OF 2 IN TEMPORAL BONES1) The diameter of geniculate fossa is 2 mm2) The distance between between geniculate fossa to anterior wall of vestibule is 2 mm3) The thickness of geniculate crest is 2 mm4 ) The diameter of horizontal facial nerve in that area is 2 mmHence while drilling the bone or curetting the bone at perigeniculate area it is not advisable to use bigger burs more than 2mm diameter5) The meatal segment of facial nerve is usually 2 mm anterior and superior to superior vestibular nerve.My special thanks to prof Livio presuitti, prof Daniele Marchioni and prof Jao Flavio Nogueira who taught me this Anatomy

BENZ wheel

SURFACE MARKING OF INTERNAL AUDITORY CANAL ON MEDIAL WALL OF MIDDLE EAR

Dear surgeons it is dissected dry temporal bone showing the surface landmark for fundus of iac . The land mark is BENZWHEEL You can observe three wings of Benz wheel So iac is present anterior to oval window

1 oval window 2 round window 3 ponticulus 4 sibiculum A Basal turn of cochlea B middle turn C apical turn

Surgical implications

1 every resident should be familier with this picture to do further transmeatal skull base surgery2 surgeon should respect antero superior part of this wheel(labyrinthine part of f n travels)while doing transcochlear approach or modified transcochlear approaches endoscopically through the meatus3 in performing cochleactomies4 for endoscopic endomeatal rerouting of fn from iac to stylo mastoid foramen 5 for removal of clival skullbase tumours7 It is front gate to extended endoscopic approaches8 For decompression of labyrinthine fn in cases of transverse fractures

• Dear surgeons it is BENZ wheel in ear 1. Superiorly it is bounded oval window 2. anteriorly by cochlea and 3. inferiorly by scala of basalturn of cochlea

The cochlear nerve from i a c entering to modiolus through the center of the wheel c in picture is cochlear nerve This is first surgical land mark for endoscopic endomeatal approach to i a c

Note the relations between vestibular window modiolus and basal turn of cochleaSurgical implications1) endoscopic cochlear neurectomy2) endoscopic approach to i a c3) Trans cochlear approaches to skull base4) c i surgery5) vestibular nerve sections

11) FN in IAC12) cochlear nerve

Endoscopic transcochlear approach

DEAR SURGEONS these are pictures of C P AngleIt is transmeatal endoscopic cadaveric dissection of c p angle 45 70 degrees of endoscopes are used through transmeatal transinternal auditory canal route is used . We can see the anterior face of cp angle here . All other procedures like retro sigmoid retrolab translab . We see posterior face here infront of us 7th nerve comes first in other procedures the vestibulo cochlear nerve bundle hides facial nerveSo here facial nerve is clearly vaisible from porus to pons

Surgical implications 1) endoscopic exposure to all pathological lesions of c p angle2) Intra cranial grafting of facial nerve we are directly visualising the intracranial portion of nerve3) other pathologies of Meckles cave4) No much bone drilling no brain retraction it is keyhole surgery for future endoscopic lateral skull Base surgeons5) The endoscopic otologist should be thorough with endoscopic anatomy of this region before applying these type of procedures

Vcn ) Vestibulocochlear nerve6th) 6th cranial nerveDc) Durello canalP) PonsIca) Internal carotid arteryIac) Anterior wall of internal auditory canalDv) Dandy veinSca) Superior cerebellar veinTen) Tentorium

endomeatal endoscopic dissection for internal auditory canal

• Dear surgeons This is endomeatal endoscopic dissection for internal auditory canal Under the horizontal facial nerve infront of Round Window including anterior part of oval window is surface land mark for ICA The steps follows:1) Posterior cochleactomy, Identification of base of modiolus2) Creation of benz wheel. Benz wheel divides promontory a) below the RW b) anteroinferiorly cochlea c) antero superiorly internal auditory canal including paresiers triangle.3) opening of posterior wall of Internal auditury canal identifying vestibular nerves.4) Anteriorly once removal of vestibular nerves cochlear and facial nerves are visible.5) The direction of these nerves are important relation once this excerise is well known endoscopic endomeatal exposure of clive and transcochlear approaches are easyMicroscopically trancochlear approach is described by pro portmann but it is not clear.Dear microscopic temporal bone surgeons you combine your microscopic bone excerise with endoscopes to give maximum benifit to residents.

• 1) Surface marking for IAC2) Vestibule 3) Modiolus 4) Spherical recess 5) Horizontal FN6) Round window 7) Modiolus 8) Posterior part of vesribule 9) RW niche 10) Medial wall of vestibule 10) Superior and inferior vestibular nerves11) FN in IAC12) cochlear nerve

11) FN in IAC12) cochlear nerve

IAC 360 DEGREES :

• IAC 360 DEGREES :• Surgeons it is cadaveric endoscopic

dissection of IAC 360 degrees.• The dissection steps are

1) Simple mastoidectomy2) Intact fallopian bridge technique3) Trans labyrinthine approach to IAC4) Trans meatal cochlectomy5) Identification of ICA6) 360 degree exposure of IAC

• Surgical implications

It is basic exercise of mastoidectomy intact fallopian bridge technique tranmeatal exposure of IAC and finally transotic approach

For transotic removal of acoustic tumours.

Here surgeon can know the relation between IAC Facial nerve and ICA

It is a combination of trans labyrinthine approach to IAC to expose its posterior surface transmeatal approach to expose anterior surface of IAC finally intact fallopian bridge technique for under surface exposure of IAC. It is done fully endoscopically.

Dear temporal bone surgeons practice this exercise you know 360 degrees of IAC and the relations with the surround structures.

1) ICA 2) Eustachian tube 3) Eochleactomy (endomeatal transcochlear route 4) IAC (360 degrees) 5) Horizontal Facial Nerve 6) Crotch 7)

Jugular bulb 8) Translab approach to IAC 9) labyrinthine Facial Nerve 10) Vestibular nerves

1) ICA 2) Eustachian tube 3) Eochleactomy (endomeatal transcochlear route 4) IAC (360 degrees) 5) Horizontal Facial Nerve 6) Crotch 7)

Jugular bulb 8) Translab approach to IAC 9) labyrinthine Facial Nerve 10) Vestibular nerves

1) ICA 2) Eustachian tube 3) Eochleactomy (endomeatal transcochlear route 4) IAC (360 degrees) 5) Horizontal Facial Nerve 6) Crotch 7)

Jugular bulb 8) Translab approach to IAC 9) labyrinthine Facial Nerve 10) Vestibular nerves

1) ICA 2) Eustachian tube 3) Eochleactomy (endomeatal transcochlear route 4) IAC (360 degrees) 5) Horizontal Facial Nerve 6) Crotch 7)

Jugular bulb 8) Translab approach to IAC 9) labyrinthine Facial Nerve 10) Vestibular nerves

1) ICA 2) Eustachian tube 3) Eochleactomy (endomeatal transcochlear route 4) IAC (360 degrees) 5) Horizontal Facial Nerve 6) Crotch 7)

Jugular bulb 8) Translab approach to IAC 9) labyrinthine Facial Nerve 10) Vestibular nerves

posterior ampullary nerve (singular nerve)

E N T surgeons it is rare video of exposure and visualising of posterior ampullary nerve (singular nerve).It arises from inferior vestibular nerve and passes through the singular foramen which is situated 1 mm medial to fundus of IAC, then it passes posteriorly towards sinus tympani. At the floor of the sinus tympani ampulla of posterior semicircular canal is present.The singular nerve supplies to the ampulla of posterior semicircular canalThe surgical landmark for this nerve is concomerata medialis and posterior lip of round window, hereby drilling posterior to Round window exposes the singular nerve,In the above video we can see- IAC- Inferior vestibular nerve- A white structure, thread like, passing from IVN in IAC, towards sinus tympani is clearly seen.The indications for this exposure are- Identification of IAC in which it guides ur towards posterior wall of IAC- Nerve section in BPPVSometimes due to its variational course we may not be able to visualise this nerve. Prof Richard R Gacek described this procedure for BPPV (Gacek's Neurectomy).https://www.facebook.com/groups/1618442198418497/permalink/1676666562596060/

See video

https://www.facebook.com/groups/1618442198418497/permalink/1676666562596060

/

Fully Endoscopic SubtemporalApproach

INDICATIONS.

The fully endoscopic subtemporal approach provides minimallyinvasive surgical access to the 1. ipsilateral petroclival, 2. Suprasellar and parasellar, cavernous sinus, and 3. medial sphenoid wing regions.

Pathologies in these areas may include 4. Hypothalamic gliomas; 5. craniopharyngiomas, especially with a prefixed-optic

chiasm; 6. trigeminal schwannomas or neurofibromas; 7. petroclival, sphenoid wing, and cavernous sinus meningiomas; 8. arachnoid cysts of the middle cranial fossa; 9. pituitary macro adenomas with major lateral extensions; 10. chordomas of the middle and upper clivus; 11. carcinomas; rhabdomyosarcomas; and other benign and malignant lesions

extending to or through the middle skull base, with or without invasion of the cavernous sinus

COMPLICATIONS

During the skin incision, the frontotemporal branch ofthe facial nerve is the most likely motor branch to be injuredbecause it is vulnerable in its superficial path as it penetratesjust below the zygomatic arch close to the temporomandibular joint and traverses an oblique course superiorly over and above the zygomatic arch. This is avoided by carefully elevating the lateral periosteum of the arch to protect the nerve and not extending the skin incision below the lower border of the zygomatic root. The course of the nerve over the zygomatic arch can be estimated by a line connecting a point 0.5 cm inferior to the tragus to a point 1.5 cm lateral to the superior brow.

The auriculotemporal nerve, a sensory branch of the mandibular division of the trigeminal nerve, lies posterior to the superficial temporal artery within the temporoparietal fascia (the surgeon may often encounter an anterior branch of the artery during the skin incision), and therefore elevation anteriorto the frontal branch of the superficial temporal artery should proceed with caution to avoid injuring this nerve. Whenever

MECKEL'S CAVE THROUGH ENDOSCOPIC SUBTEMPORAL APPROACH

• Today I have done Radio frequency gangliolysis of Gassarian ganglion for severe Trigeminal neuralgia through fully endoscopic subtemporal fossa extra dural approach. 'C' shaped, 2 cm preauricular incision, mini craniotomy separation of mid fossa dura from Temporal bone, middle menengial artery coagulation, Identification and following the GSPN, foramen ovale, mandibular nerve, Extradural Isolation of Gassarian Ganglion by KAWASE method and radio frequency lysis of ganglion are the steps.Through this fully endoscopic approach, Merkel's cave and Gassarian Ganglion are visualised.For a better understanding, Cadaveric dissection of middle cranial fossa is posted here..Patient was having severe neuralgia prior to this surgery, now the the pain is temporarily subsided.. Long term results are awaited.

The Fully Endoscopic RetrosigmoidApproach = MIRA

MIRA = Minimally invasive retrosigmoid approach

subarcuate artery• Dear surgeons drVetrivel showed us subarcuate artery usually

it is eaither branch of labyrinth artery or from aica asit passes through iac it sends branch to petrous apex and its branches to posterior meningeal artery and superficial petrosal artery then it passesthrough the petromastiod orantro cerebellar canal of Chatellier and comes to antrm under the.arch.of ssc to supply medial wall of antrum The surgical implications are1 it is surgical land mark for a light house sign b to guide to subsrcuate endoscopy to internal auditory canal c to follow the vein of Els worth Luscas lake The rule of 4 is applicable here

SSC dehiscence = Superior semi circular canal dehiscence

Endoscopic repair of SCCD

Video of endoscopic SCCD https://youtu.be/yTiF_OGrbEo

Microscopic repair of SCCD• MCV Clinics #012

GIDDINESS...Corrected by simple surgery• Surgically correctable causes of giddiness include Superior

SCCDehiscence (congenital), Lateral SCC Dehiscence (cholesteatoma/ Iatrogenic), etc.All inner ear diseases – accurate diagnosis is more critical than the management.Only HRCT is useful and Plain CT Brain will not pick it up. Caloric responses may be variable.

• Case of a 67yr.old with recurrent vertigo lasting 2-3hrs for 5 months, triggered by bending down and getting up.Our patient had a Transmastoid exposure of labyrinth, thinning of tegmen antri, followed by exposure of Superior SCC Arch under GA. Oncedehiscence was exposed it was plugged with periosteum.

• — with Anand Veluswamy.

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