Download surgical anatomy for endoscopic sphenoethmoidectomy

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Middle meatus
Hiatus semilunaris superior
Maxillary sinus
Maxillary sinus, natural ostium
Infraorbital cell (Haller cell)
Uncinate process and Uncinectomy
Frontal recess
Middle turbinate, basal lamella
Posterior ethmoid
Onodi cell
Sphenoid sinus
Internal carotid artery
Cavernous sinus
Inspected to assess
(a) the shape and size of the
middle Turbinate
(b) the ethmoid bulla
(c) the free margin of the
uncinate process and the
line of attachment to the
frontal maxillary process
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The frontal recess always continues
with the mucosa on the lateral
surface of the middle turbinate and
is located anteriorly to the frontal
wall of the ethmoid bulla and
communicates with the ethmoid
infundibulum
The location may vary depending
on the number and volume of the
pneumatized cavities in the frontal
bone, the nasal bone, the lacrimal
bone and the agger nasi, and may
not always be visible through the
middle nasal meatus
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The drainage opening of
the hiatus semilunaris
superior, visible from the
conchal sinus (the space
between the middle
turbinate and the medial
wall of the ethmoid bulla)
communicates with the
lateral sinus posterior to
the ethmoid bulla.
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The lateral sinus is formed by:
1. Suprabullar recess (anterior and superior parts)
 Inferior by ethmoid bulla
 Superior by fovea ethmoidalis
2. Retrobullar recess (posterior and inferior parts)
 Anterior by ethmoid bulla
 Posterior by oblique portion of basal lamella
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When the ethmoid bulla is attached to the
ethmoid roof superiorly there is no
suprabullar recess; when the bulla attaches to
the basal lamella of the middle turbinate
inferoposteriorly there is no retrobullar
recess.
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Posterior nasal fontanelle
between the inferior
margin of the ethmoid
bulla and the horizontally
oriented inferior margin
of the uncinate process.
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If an opening becomes
visible in this area before
the inferior half of the
uncinate process is resected,
this always belongs to the
accessory maxillary ostium.
The natural maxillary ostium
lies lateral to the uncinate
process and comes only into
sight after resection of the
uncinate process.
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Is a three-dimensional cavity, is located
lateral to the hiatus semilunaris inferior, a
two-dimensional opening between the free
margin of the uncinate process and ethmoid
bulla.
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Neighbouring structures:
◦ Frontal wall of ethmoid bulla
posteriorly.
◦ Uncinate process and the frontal
maxillary process anteriorly.
◦ Lamina papyracea and the
posterior nasal fontanelle
laterally.
◦ Hiatus semilunaris inferior and
the uncinate process medially.
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Prominence that runs
from posterior to
anterior along the
superior maxillary
sinus wall belongs to
the infraorbital nerve
The natural maxillary
sinus ostium which
normally has an elliptic
shape.
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View of the natural
ostium medially, the
middle meatus, the side
of the uncinate process
facing the hiatus
semilunaris and the
inferior margin of the
ethmoid bulla can be
partially seen.
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Is located lateral to the
uncinate process, at the level
where superior vertical
segment of uncinate process
merges with inferior
horizontal segment.
The anterosuperior margin of
the maxillary sinus ostium is
of elliptic shape and located
more laterally; its
posteroinferior margin lies
more medially, so when
viewed through the 0°
telescope a projection of the
maxillary sinus ostium
becomes visible.
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formed by pneumatization of the lacrimal
bone developing towards the orbital floor,
may narrow the maxillary ostium, and
account for persistent or recurrent sinusitis if
overlooked and not opened
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Once the 30° telescope is
located in the maxillary
sinus cavity the
prominent Haller cell can
be identified and incised
below the inferior margin
of the ethmoid bulla at
the posterosuperior
margin of the natural
ostium.
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Using the sickle knife: Initially the uncinate
process is incised with the sickle knife and then
outfractured by use of Blakesley forceps, which
is the usual approach for total uncinectomy.
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The procedure has certain disadvantages
 When the uncinate process is very close to the
lamina papyracea, the sickle knife might superiorly
fracture the lamina papyracea and the periorbital.
 In the event of a pneumatized uncinate process the
incision might not reach as far as the ethmoid.
CT image of the uncinate process
located close to the lamina
papyracea.
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The procedure has certain disadvantages
 If the incision, made at the inferior end of the horizontal portion of the uncinate process, is not carried
backwards posteriorly to a sufficient extent, the
remaining portion may impair vision of the maxillary
sinus ostium
 If the incision is made too far anteriorly, the anterior
portion of the maxilla - a thick bone - is encountered which in turn may impede the attempt of
incising the uncinate process
 If the incision is made too close to the free margin
of the uncinate process, uncinate remnants may
obstruct vision of the foremost anterior ethmoid
cells and agger nasi cells which need to be resected.
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Using the miniature backbiting
nasal forceps: Once the first
uncinate process incision has
been made at the insertion point
of the vertical and horizontal
segments the maxillary sinus
ostium should come into view;
the lower half of the uncinate
process is resected with a sharp
curette, Stammberger antrum
punch, or back-biting nasal
forceps. The upper half of the
uncinate process may be initially
preserved to identify the frontal
recess and its neighbouring
ethmoid cells and finally
resected in a controlled manner
with a curette or through-cutting
forceps.
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If the uncinate process
bends laterally and
inserts onto the lamina
papyracea a blind end
called terminal recess
(recessus terminalis)
appears lateral to the
superior attachment of
the uncinate process
following uncinectomy
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Surrounded by:
◦ Agger nasi cells anteriorly
◦ Frontal cells posteriorly,
and superiorly
◦ Lacrimal cells posteriorly
and interiorly
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Preservation of the
superior attachment of
the uncinate process:
◦ Lacrimal cells, frontal
cells, agger nasi cells and
the terminal recess
located lateral to it.
◦ Frontal recess located
medial and posterior to it.
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The medial line of the
frontal recess lies on
the continuation of the
lateral wall of the
middle turbinate.
In the event of a well
pneumatized frontal
bone, frontal cells can
be found between the
superior end of the
uncinate process and
the frontal recess
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There are no cells
between the frontal
recess and the lateral
margin of the middle
turbinate, and the
recess is consistently
anterior to the
superior insertion of
the anterior wall of the
ethmoid bulla
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Excision of the ethmoid
bulla is usually not
necessary for
identification of the
frontal recess; the frontal
recess can be traced by
following the lateral
portion of the middle
turbinate, the anterior
wall of the ethmoid bulla
and the superior end of
the uncinate process.
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The opening, superior to
the anterior wall of the
ethmoid bulla, lateral to
the superior insertion of
the bulla, posterior to the
superior insertion of the
uncinate process, and
lateral to the frontal recess
communicates with the
frontal bulla
The frontal bulla has a
blind end at the floor of
the frontal bone and
should not be confused
with the frontal recess.
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Three different points of
insertion of the superior
end of the uncinate
process:
◦ Middle turbinate
◦ Lamina papyracea
◦ Skull base
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Might be attached to
more than one point
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The ethmoid bulla is the
largest and the most
interiorly located among
the anterior ethmoid
cells.
Safest entrance point is
inferomedial.
The bulla cavity can be
exposed with a Blakesley
forceps or a sharp
curette.
Once inside the bulla
cavity the basal lamella of
the middle turbinate can
be identified by viewing
backwards
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Is divided into two parts as oblique and
horizontal.
Horizontal portion must not be damaged
because:
◦ Static stability of the middle turbinate is impaired,
or necrosis of the middle turbinate postoperatively.
◦ Bleeding from branches of the sphenopalatine
artery may be triggered.
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Shape of oblique portion may be variable
depending on degree of pneumatization of
anterior and posterior ethmoid cells.
◦ Pneumatization of the suprabullar recess:
 insertion of basal lamella to skull base superiorly is
located posterior to nferior part of oblique segment
◦ Pneumatization of retrobullar recess:
 inferior part of basal lamella assumes a more
posterior position and superior attachment to skull
base assumes a more anterior position
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When the anterior wall of
the ethmoid bulla and the
superior attachment of the
basal lamella of the middle
turbinate are elevated.
anterior to posterior, the
frontal recess and hiatus
semilunaris superior
medially, and in lateral
position the frontal bulla,
the superior boundary of
the suprabullar recess and
the superior boundary of
an anterior ethmoid cell
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The frontal bulla, lateral
to the frontal recess
constitutes the roof of
the frontal cells and
may be pneumatized
towards the orbital roof;
in such cases a
Supraorbital cell can be
seen
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Anterior ethmoid artery,
usually passing through a
thin bony canal, enters the
ethmoid roof laterally from
the lamina papyracea and
extends anteromedially
towards the middle
turbinate
Divides the ethmoid fovea
into:
◦ anterior ethmoid fovea
◦ posterior ethmoid fovea
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The anterior ethmoid artery
limits the anterior fovea
fovea posteriorly, not the
frontal recess
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The cavity lateral to the
anterior ethmoid roof
delineated by the
anterior ethmoid artery
posteriorly is a
supraorbital cell,
located superomedially
to the orbit and
posterior to the frontal
bulla
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Once the bony lamellae
adjacent to the frontal
recess are completely
removed the frontal
sinus lumen can be
viewed through its
ostium or canal.
The vertical lamella of
the middle turbinate is
attached to the
cribriform plate of the
ethmoid sinus medial
to the fovea.
(weakest skull base)
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Nasal cells may form
as a result of
pneumatization
anterior to the
frontal recess and
posterior to the
superior insertion of
the uncinate process
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Access to the posterior
ethmoid cells is
achieved once the
oblique portion of the
basal lamella of the
middle turbinate has
been reached.
The safest point for the
initial dissection of the
basal lamella is the
inferomedial portion
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Once the superior
portion of the basal
lamella is removed and
the skull base comes into
view, the posterior
ethmoid artery travelling
from lateral to medial
almost parallel to the
coronal plane of the skull
base can be identified on
average 12 mm behind
the anterior ethmoid
artery
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The posterior ethmoid
artery travels in a thin
bony canal at the skull
base.
The artery is usually
accompanied by the
ethmoid nerve in the
same bony canal but, as
seen in the example
above, the posterior
ethmoid artery and
posterior ethmoid nerve
may also run separately
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The anterior wall of the sphenoid sinus can
be identified by:
◦ lies inferomedial to the ethmoidectomy cavity and
at a distance of 6.5 cm on average from the anterior
maxillary crest in adult.
◦ lies 1 cm anterior and superior to the superior
boundary of the choana.
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The sphenoethmoid
recess lies superolateral
to the vertical crus formed by the basal
lamella of the middle
turbinate (2) - of an
imaginary "Y" formed by
the posterior nasal
fontanelle, the horizontal
portion of the basal
lamella of the middle
turbinate and the orbital
floor. The sphenoid sinus
lies medial to the
sphenoethmoid recess
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pneumatized posterior
ethmoid cell superolateral to
the sphenoid sinus.
Optic nerve or even the
internal carotid artery may
run through it
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In the presence of an
Onodi cell the anterior
wall of the sphenoid
sinus lies to the
anterior, medial and
inferior of it. Taking
into account that the
orbital apex lies 1-8
mm (5 mm on average)
behind the posterior
ethmoid artery can be
helpful in locating the
optic nerve.
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After the anterior wall
of the sphenoid sinus is
dissected and the
opening enlarged, the
lamella separating the
sphenoid sinus and the
Onodi cell attaching to
the optic nerve come
into view. The lamella
segment adjacent to
the optic nerve should
not be resected.
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The prominences of the
sella, optic nerve and
internal carotid artery can
almost always be identified
when the sphenoid sinus
cavity is inspected.
the prominences of the
maxillary nerve at the
lateral wall and the vidian
nerve at the inferior wall of
the sphenoid sinus can
occasionally be observed
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The internal carotid
artery has been
demonstrated by opening
the posterolateral wall of
the sphenoid sinus to
expose structures which
are associated with the
risk of complications
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When the internal carotid
artery is retracted
medially, the veins of the
cavernous sinus, the
suspensory ligaments of
the internal carotid artery
and the abducent nerve
superolateral come into
view.
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When total
sphenoidectomy is
complete, the lamina
papyracea is removed
and the orbital apex
can be identified
without the risk of
damaging the orbital
periosteum, as in
endoscopic optic nerve
decompression
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The bony canal of the
medial wall of the optic
nerve is resected with
a diamond burr or thin
dissector and the
Zinn's ring ligaments
extending
perpendicular to the
longitudinal axis of the
nerve at the level of
the orbital apex are
identified.