EXERCISE 19

ENDOSCOPIC ENDOMEATAL DISSECTION OF JUGULAR FORAMEN

STEP A – VISUALISATION OF HYPOTYMPANUM.
The hypotympanum is visualised using 0 degree endoscope.
Here trabeculae are observed in hypotympanum. It generally indicates that the distance to jugular bulb to floor of hypotympanum is 9 to 10 mm.
It is associated with cellular mastoid and posteriorly placed sigmoid sinus.

Labelling:
T – Trabiculae
F – Funiculus

STEP B – DRILLING OF HYPOTYMPANUM.
The hypotympanum is gentlly drilled with diomond bur or piezzo electric blade .
Piezzo blade removes the bone leaving soft tissue undamaged.

STEP C – EXPOSURE OF CROTCH.
Careful drilling of floor of hypotymanum including tympanic bone forming lateral wall of hypotympanum exposes the crotch.
Crotch is jugulo carotid septum contains inferior tympanic artery and jocobsons nerve.
Exposure of hypotympanum includes skeletonization of ICA, carotid foramen and jugular bulb

Labelling:
1 – ICA
2 – Jugular bulb
3 – Crotch
4 – Jocobsons nerve cut ends

STEP D – COMPLETE EXPOSURE OF HYPOTYMPANUM.
Complete exposure of anteriory placed ICA, posteriorly placed jugular bulb and crotch are necessory to expose jugular foramen completely through endoscopic endomeatal approach.
For that the tympanic bone is drilled infero laterally to expose jugular foramen
The boundaries of jugular foramen laterally are anteromedially ICA and posterolaterally styloid process

Labelling:
1 – ICA
2 – Jugular bulb
3 – Crotch

STEP E – COMPLETE VISUALISATION OF HYPOTYMPANUM.
The hypotympanum including jugular bulb ICA are visualised.
The crotch is thinned, the opening of inferior tympanic artery is seen.
Normally it is deeper to jocobsons nerve

Labelling:
1 – Opening of inferior tympanic artery
2 – Thinned out crotch
3 – ICA
4 – Jugular bulb

STEP F – REMOVAL OF CROTCH.
Gentle thinning of crotch with diamond drill elivation from ICA and jugular bulb and removal with elivater exposes the ICA jugular bulb area.
Removal of crotch is similar to removal crista galli in transcribriform approach in anterior skull base exposure

Labelling:
1 – Removal and displaced crotch
2 – ICA
3- Jugular bulb

STEP G – SEPERATION OF FIBROUS TISSUE BETWEEN ICA AND JUGULAR BULB.
The fibrous tissue is genltly seperated with elivater

Labelling:
ICA – Inernal carotid artery
FT – Fibrous tissue
JB – Jugular bulb area

STEP H – VISUALISATION OF CAROTID JUGULAR BULB JUNCTION
Inter jugulocarotid region is clearly visualised after seperation of fibrous tissue jugular bulb is pushed posteriorly

Labeling:
ICA – Internal carotid artery
JB – Jugular bulb.
ENDOSCOPIC ENDOMEATAL DISSECTION OF JUGULAR FORAMEN(CONT)


This is direct lateral endoscopic approach of jugular foramen .Anteriorly ica ,
posteriorly jugular bulb and in the middle the lower cranial nerves are visualised through middle ear.It is possible to see jugular foramen and lower cranial nerves through the middle ear with 0degree endoscopes


STEP..H
IDENTIFICATION OF GLASSOPHARYNGEAL NERVE.Once the space between ica and jugular bulb is identified and jugularbulb pushed posteriorly the 9th cranial nerve identified .The nerve
lateral and close to ica
Ica..internal carotid artery
1..Glassopharyngeal nerve
JB..jugular bulb


STEP H1..
ELIVATION OF 9TH CRANIAL NERVE..The 9th nerve is gently elivated from surrounding with sickle knife or with probe .Surgeon can see inferior petrosal sinus passing anteriorly between 9th and 10th cranial nerves
1..9th cranial nerve


STEP I
IDENTIFICATION OF VAGUS NERVE..Vagus nerve identified more medially in between ica and jugular bulb
9th..Glasso pharyngeal nerve
10th..vagus nerve
11th..proximak portion of accessory nerve


STEP J
IDETIFICATION OF ACCESSORY NERVE..Pushing jugular bulb posteriorly the 11th C nerve is identified posterio to vagus and medial to the jugular bulb
Ica
..internal carotid artery
10..vagus nerve
11..Accessory nerve
JB..jugular bulb


STEP K
OPENING OF JUGULAR BULB …The juvular bulb is opened eith sickle knife
1..lumen of jugular bulb


STEP..L
INFERIOR PETROSAL SINUS
Once the jugular bulb is opened the inner opening is visualised
antero inferior portio of jb .There may be 2 or 3 openings in the inner wall of j b
1…sigmoid sinus
2 ..inner wall of jb
3…probe in inferior petrosal sinus


STEP M
VISUALISATION OF MARGO SIGMOID TERMINUS…There is ridge of bone is present at the junction of sigmoid sinus and jugular bulb region .it is visible clearly like a crest
1..Margo sigmoid terminus
2 Sigmoid sinus
3..jugular bulb lumen

D