ENDOSCOPIC SINUS SURGERY
Section 5 ()قسمت پنجم فایل
Bakhshaee M, MD
Rhinologist, Assistant Prof. MUMS
Frontal Sinusotomy (I, II, III)
This procedure involves opening of the frontal recess
together with an anterior ethmoidectomy
Frontal sinusotomy I
No instrumentation of the frontal recess is required
when the uncinate process is attached to the skull
base or middle turbinate; when the uncinate process
has been removed, the recess is open unless there
1. Large agger nasi air cells
2. Bulla frontalis
3. Supraorbital cell
Frontal sinusotomy II
Enlarging the frontal recess by the submucosal
removal of agger nasi air cells, bulla frontalis, or a
Frontal sinusotomy III
Extended enlargement with removal of the
frontonasal spine or “beak”.
There are few other reasons for operating on the
frontal recess before trying a partial anterior
1. The presence of fungal disease in the frontal sinus
4. Other pathology in this area that requires wide exposure
Access to the frontal recess may be altered by the
attachment of the uncinate process
Where the uncinate process attaches to the lateral
nasal wall so the frontal sinus drains into the middle
The uncinate process attaches to the skull base
The uncinate process attaches to the middle
Agger Nasi & Bulla Frontalis
A high anterior ethmoidal cell that has pneumatized
into the frontal bone is called the bulla frontalis and
this can displace the frontal recess posteriorly
The supraorbital cell extends up into the frontal
sinus posterior to the frontal recess.
Supraorbital cell can extend over the skull base
The surgeon must have a good
reason for operating in this area.
The landmarks that will help you
are the remains of the uncinate
process, the remainder of the
anterior wall of the ethmoid bulla,
and a knowledge of the air cells
from the CT scan.
Uncapped agger nasi cells,
the terminal recess, and the
ethmoid bulla form domes
that are joined together.
It often appears that this is all
there is and they might fool
you into thinking that one of
them is a small frontal sinus.
The aim is to open this crevice,
which will turn out to be the
pathway to the frontal recess
and the frontal sinus, by
“deflating” the cells.
This is best done by passing the
ball probe well above their
domes and gently lateralizing
Anterior ethmoid artery
You should not go searching for the anterior ethmoid
artery as it is not a useful landmark and to do so is
It is important to be aware that it is partially dehiscent
in 20% of patients.
If the skull base is very well pneumatized, the artery
can even be free like a tightrope, especially if there is
a large supraorbital cell.
This is an extension of a partial anterior
ethmoidectomy that involves surgery into the
posterior ethmoid sinuses and the sphenoid sinus
A sphenoid sinusotomy is a transnasal approach to
open the sphenoid sinus
Sphenoid sinusotomy can be classified into types I,
II, and III depending on its size.
A sphenoethmoid (Onodi) cell
has part of its extension lateral
to the lateral wall of the
sphenoid, which means that the
optic nerve is likely to be
Its natural ostium lies high in the anterior wall of the
sphenoid and can be hidden by the superior and
The roof of the sphenoid sinus is a reliable
landmarkand the posterior ethmoid sinuses do not
drop below this horizontal level of the skull base
The vomer meets the sphenoid in the midline, but the
sphenoid inter sinus septum is symmetric in over
75% of patients
The lateral wall of the sphenoid contains the carotid
artery, which is dehiscent in 30% of patients
The superolateral aspect of the sphenoid sinus
contains the optic nerve, which is visible in 20% of
The posterior ethmoidal cells are entered through
the basal lamella and it is safest to enter these
medially and inferiorly.
Enlarge access to these cells and avoid making a
Always find the sphenoid sinus transnasally first if
you intend opening up all the posterior ethmoid
landmarks to avoid traversing the boundaries of the paranasal
Check the CT scan to see that there is no Onodi cell
as the optic nerve can sometimes be dehiscent in its
Look at the posterior coronal CT slices of the
maxillary sinus and look at the height from the roof
of the maxillary sinus to the roof of the skull base.
Sometimes this can be spacious but sometimes it is
small and it will give the operator an idea of the
extent of the posterior ethmoidal air cells.
The roof of the sphenoid sinus is a useful landmark
as the posterior ethmoid sinuses are not lower than
The posterior ethmoid sinuses that lie medial to the
medial wall of the maxillary sinus in a sagittal
plane can be removed without concern that the
optic nerve or orbit will be damaged.