Medial Maxillectomy
Medial Maxillectomy
Medial Maxillectomy
Bony anatomy
Maxillary sinus
Inferior turbinate
Fovea ethmoidalis
Lacrimal sac in lacrimal fossa
Anterior ethmoidal foramen
Anterior end of maxillary sinus
Lamina papyracea
Infraorbital nerve
2
Medial maxillectomy is done medial to the
Posterior ethmoidal foramen infraorbital nerve.
Optic nerve
Lamina papyracea
Ground lamella
Infraorbital nerve
Inferior orbital fissure
Nasolacrimal duct
Zygoma
Sphenopalatine foramen
Pterygopalatine fossa
The bony anatomy of the hard palate is
illustrated in Figure 11.
Pterygomaxillary fissure
Pterygoid plates
3
Vasculature
Angular vein
Angular artery
Infraorbital
artery
4
inferiorly from the pterygopalatine from the anterior lacrimal crest and
fossa through the pterygopalatine canal approximately 6 mm (5-11 mm) from
(Figure 1) and emerges from the the posterior ethmoidal foramen
greater palatine foramen of the hard
palate (Figure 11). It then runs Nerves
anteriorly medial to the superior
alveolus and enters the incisive The maxillary division of V (V2) enters
foramen (Figure 11). the pterygopalatine fossa via foramen
Infraorbital artery: It courses in the rotundum. The only branch of surgical
infraorbital groove and canal with the significance is the infraorbital nerve. It
infraorbital nerve in the floor of the runs in the floor of the orbit/roof of the
orbit/roof of antrum and exits antrum to exit from the infraorbital
anteriorly via the infraorbital foramen foramen (Figure 15). The only other major
to supply the overlying soft tissues of nerve that has to be considered at
the face (Figures 12, 14). maxillectomy is the optic nerve.
Sphenopalatine artery (Figure 14): It
enters the nasal cavity through
sphenopalatine foramen at the back of
the superior meatus where it gives
origin to posterior lateral nasal
branches.
Posterior septal artery: This is a
branch of the sphenopalatine artery and
crosses the posterior nasal cavity just
above the posterior choana to end on
the nasal septum; one branch descends
in a groove in the vomer to enter the
incisive canal and anastomose with the
greater palatine artery. Figure 15: V2, pterygopalatine ganglion
and infraorbital nerve
Branches of the internal carotid artery of
surgical significance include: Orbital structures
Anterior ethmoidal artery: It
originates from the ophthalmic artery Post ethmoidal for
and enters the orbit through the anterior Ant ethmoidal for
ethmoidal foramen (Figure 3) which is
Frontoethmoidal
located 25 mm from the anterior suture
Optic foramen
lacrimal crest Lamina papyracea
Posterior ethmoidal artery: It Sup orbital fissure
Lacrimal fossa
originates from the ophthalmic artery Inf orbital fissure
and enters the orbit through the Infraorbital foramen
posterior ethmoidal foramen (Figure 3,
7). It is located approximately 36mm
from the anterior lacrimal crest, and
12mm (8-19 mm) from the anterior Figure 16: Right medial orbital wall
ethmoidal foramen
Ophthalmic artery: It emerges with the Figure 16 shows the detailed bony
optic nerve from the optic canal, 44mm anatomy of the orbit. During dissection of
5
the orbit, the following structures are related to the lacrimal drainage system.
encountered: medial palpebral ligament, It lies anterior to the canaliculi, but a
orbital septum, lacrimal sac, periosteum, deep head inserts into the posterior
anterior and posterior ethmoidal arteries lacrimal crest and onto the fascia of the
and inferior orbital fissure (Figure 16, 17). lacrimal sac.
Only when doing orbital exenteration is the Lacrimal sac (Figures 1, 3, 4, 16, 17,
superior orbital fissure encountered. 18): It is located in the lacrimal fossa,
Orbital septum (Figure 17): This which is bound medially by the
connective tissue structure attaches lacrimal bone and the frontal process of
peripherally to the periosteum of the the maxilla (Figure 1, 16). It is related
orbital margin and acts as a diaphragm anteriorly, laterally, and posteriorly to
that retains the orbital contents. the medial palpebral ligament.
Laterally, it is attached to the orbital
margin 1.5mm anterior to the
attachment of the lateral palpebral
ligament to the lateral orbital tubercle.
The septum continues along the
superior orbital rim. Superomedially it
crosses the supraorbital groove, passes
inferomedially anterior to the trochlea,
and follows the posterior lacrimal crest
behind the lacrimal sac. It then crosses
the lacrimal sac to reach the anterior
lacrimal crest, passes inferiorly along
the anterior lacrimal crest and then
laterally along the inferior orbital rim.
Supraorbital
groove
Lacrimal sac
Figure 18: Right lacrimal system
6
Superior Frontal n
orbital fissure ethmoids. CT scan is an important means
of anticipating the extent of maxillectomy
VI n that is required and to assess the anatomy
Lacrimal n
of the skull base and paranasal sinuses.
Once a tumour involves orbital fat, extends
Optic
foramen inferiorly to invade the palate or nasal
floor, extends laterally beyond the
infraorbital foramen, or involves the
posterior antral wall and beyond, then
more extensive resection is required.
VI n
III n
Surgical steps
Inferior orbital fissure
8
around the infraorbital foramen so as to
protect the nerve and to avoid bleeding
from the infraorbital vessels (Figure
24). Inspect the antrum to determine
the extent of the tumour and to plan the
subsequent bony cuts.
Orbital Lamina
periosteum AEA papyracea
Bony resection
9
through the thick inferior orbital rim
just medial to the infraorbital nerve.
2. Osteotomy connecting antrostomy
with nasal vestibule: A sharp
osteotome is used to connect the
anterior antrostomy with the floor of
the nasal vestibule.
3. Osteotomy across frontal process of
maxilla: This part of the dissection
is often best done with a Kerrison’s
rongeur or oscillating saw. There is
often persistent minor bleeding from
Figure 26: Coronal CT demonstrating the bone that may be controlled with
resected lateral nasal wall including bone wax or cautery. The osteotomy
inferior turbinate and uncinate process, is stopped short of the level of the
orbital floor up to infraorbital nerve, frontoethmoidal suture.
lamina papyracea and anterior 4. Osteotomy along orbital floor:
ethmoidectomy, with preservation of the While retracting and protecting the
middle turbinate orbital contents with a narrow
copper retractor an osteotomy is
continued posteriorly through the
thin bone of the orbital floor/antral
roof using either a sharp osteotome
or heavy scissors, aiming for the
posteromedial corner of the roof of
the maxillary sinus
5. Osteotomy along floor of nose: A
sharp osteotome or heavy scissors is
used to divide the lateral wall of the
nose/medial wall of the antrum
along the floor of the nasal cavity up
Figure 27: Coronal CT more posteriorly to the posterior wall of the antrum.
demonstrating resected lateral nasal wall, When doing this dissection with an
inferior turbinate and inferomedial orbital osteotome, the dissection is halted
wall, and ethmoidectomy with resection when the osteotome hits up against
remaining below the level of the posterior the solid pterygoid bone (signalled
ethmoidal foramen, and with preservation by a change in the sound).
of middle turbinate 6. Osteotomy through lacrimal bone,
lamina papyracea and anterior
ethmoids: It is critical that this
The sequence of the osteotomies is
osteotomy be placed below the level
planned to reserve troublesome
of the frontoethmoidal suture line
bleeding to the end (Figure 28). This
and the ethmoidal foramina so as to
may have to be adjusted depending on
avoid fracturing or penetrating
the location and extent of the tumour.
through the cribriform plate. The
osteotomy is done be gently tapping
1. Osteotomy through inferior orbital
on an osteotome to enter the
rim: A sharp osteotome/power
ethmoid air cell systems while
saw/bone nibbler is used to cut
10
carefully retracting the orbital and the posterior ethmoids cells, and
contents laterally. The osteotomy remaining lateral to and preserving the
stops short of the posterior middle turbinate.
ethmoidal artery so as to safeguard The specimen is inspected to determine
the optic nerve. the adequacy of the tumour resection.
7. Vertical posterior osteotomy An external ethmoidectomy may safely
through posterior ethmoids and be completed up to the cribriform
along posterior wall of antrum and plate.
pterygopalatine fossa: The final The ethmoids are carefully inspected to
posterior vertical cut is made with a determine whether an external
heavy curved (Mayo) scissors as a frontoethmoidectomy +/- sphenoidec-
downward continuation of the tomy is required, and for evidence of a
osteotomy in (6). It runs though the CSF leak.
medial wall of the maxillary sinus,
starting superiorly at the posterior
end of the previous osteotomy, and Closure/Reconstruction
ending at the level of the nasal floor.
Haemostasis is achieved with cautery,
bone wax and or topical haemostatics. It is
only rarely necessary to pack the nose.
12