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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4453_Библиотеки_им_академика_М_И_Перельмана
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210
A.
B. Horizontal segment of the
C.
A.
facial nerve
B.
C.
D.
facial nerve
E.
F.
G.
facial nerve
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Cochleariform process
facial nerve
Anterior epitympanic recess
X. Gao et al.
Fig. 8.11 Dislocate the malleus and explore the anterior epitympanic
recess (right)
Pull down the head of the malleus with a right- angle hook and fully
expose the epitympanum and anterior epitympanic recess. Observe the
Labyrinthine segment of the
Geniculate ganglion
GSPN
Horizontal segment of the
Cochleariform process
Pyramid segment of the
facial nerve
Mastoid segment of the
pink horizontal segment of the facial nerve and white cochleariform
process
Instruments: right-angle hook, suction apparatus
Fig. 8.12 Expose the geniculate ganglion and labyrinthine segment of
the facial nerve (right)
Resect the chorda tympani, cut the tensor tympani tendon and remove
the malleus. Drill off the bone above the horizontal segment of the
facial nerve to expose the geniculate ganglion and the labyrinthine segment of the facial nerve. Observe the GSPN passing forward from the
geniculate ganglion
Instruments: small-sized diamond burs
8 Infratemporal Fossa Approach
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211
A. Remnants of the tympanic
bone
B. Mastoid segment of the
facial nerve
C. Digastric ridge
D. Sigmoid sinus
E. Jugular bulb
F. Occipital bone
Fig. 8.13 Junction of the sigmoid sinus and the jugular bulb (right)
The sigmoid sinus is located at the back of the mastoid. The location of
the jugular bulb is variable. The jugular bulb is usually medial to the
mastoid segment of the facial nerve and below the tympanic cavity. It
can be exposed by working along the lower segment of the sigmoid
sinus. Care should be taken when outlining the jugular bulb to avoid
injury to the posterior semicircular canal and vertical segment of the
facial nerve
A. Stylomastoid foramen
B. Mastoid tip
C. Stylomastoid artery
D. Jugular bulb
E. Sigmoid sinus
Fig. 8.14 Stylomastoid artery (right)
There are two notches located medial to the mastoid tip that accommodate the posterior belly of the digastric muscle and the occipital artery.
Open the digastric muscle ridge and identify the stylomastoid artery
medial to the digastric muscle
Instruments: medium-sized cutting burs, right- angle hook
212
A.
B. Posterior belly of the
A.
B.
C. Lateral semicircular canal
D.
E.
F.
G.
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Stylomastoid foramen
digastric muscle
X. Gao et al.
Fig. 8.15 Excise the mastoid tip (right)
Drill off the tympanic bone, the posterior wall of the mastoid, and bone
around the posterior belly of the digastric muscle with medium-sized
diamond burs, then excise the mastoid tip
Tympanic opening of the
Eustachian tube
Tegmen tympani
Tympanic sulcus (anterior)
Stylomastoid foramen
Posterior semicircular canal
Jugular bulb
Fig. 8.16 Full view of the facial nerve in the temporal bone (right)
The facial nerve is transposed in the type A infratemporal fossa
approach, while in the type B and C infratemporal fossa approaches it
can be left in its normal position. When transposing it, the facial nerve
must be mobilized from the stylomastoid foramen to the geniculate
ganglion. In some cases with well-pneumatized mastoids, the labyrinthine segment of the facial nerve can be partly observed without excision of any of the labyrinth
Instruments: medium-sized diamond burs, surgical knife
8 Infratemporal Fossa Approach
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213
A. Labyrinthine segment of
the facial nerve
B. Geniculate ganglion
C. GSPN
D. Horizontal segment of the
facial nerve
E. Lateral semicircular canal
F. Stapes
G. Cochleariform process
Fig. 8.17 Dissect the pyramid and mastoid segments of the facial nerve
(right)
Outline the bony canal of the facial nerve in the temporal bone in a
spiral fashion until only a thin bone shell is left, then remove the bone
shell with a right-angle hook. (The spiral approach refers to exposure of
the nerve posteriorly in the mastoid segment, laterally at the second
genu, and inferiorly along the horizontal segment which allows preser-
vation of other important structures close to the nerve). Once the facial
nerve is exposed for 1/2–2/3 of its circumference, separate it from the
canal with a middle ear elevator. The epineurium should not be incised.
To avoid any injury, the facial nerve should not be elevated before adequate opening of its bony canal
Instruments: medium- and small-sized diamond burs, right-angle hook,
middle ear elevator
214
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X. Gao et al.
A. Facial nerve (dislocated)
B. Fallopian canal (the
remaining part)
Fig. 8.18 Dislocate the facial nerve from its bony canal (right)
Free the facial nerve along its bony canal from the stylomastoid foramen to the geniculate ganglion. Create a groove in the bone on the anterior bony wall of the epitympanum to accommodate the repositioned
facial nerve. No bony fragments should be left outside the geniculate
ganglion to avoid penetrating the facial nerve when repositioning it.
Retaining the bone medial to the geniculate ganglion is helpful to protect the blood supply and reduce the incidence of postoperative facialnerve paralysis
Instruments: medium- and small-sized diamond burs, right-angle hook,
middle ear elevator
A. Mastoid segment of the
B.
C.
D. Parotid gland
8 Infratemporal Fossa Approach
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facial nerve
Facial nerve at the
stylomastoid foramen level
Main trunk of the
extratemporal facial nerve
215
Fig. 8.19 Exploration of the main trunk of the extratemporal facial
nerve (right)
Using ophthalmic scissors, the soft tissue anterior to the stylomastoid
foramen can be removed layer by layer parallel to the course of the
facial nerve. The extratemporal facial nerve is explored and the main
trunk is freed for approximately 1cm to reduce stretching of the nerve
during its transpositioning
Hints: When exploring the extratemporal facial nerve, the direction of
separation should be parallel to the direction of the facial nerve bers
to prevent facial nerve injury
Instruments: ophthalmic scissors, ophthalmic forceps
216
A. Mastoid segment of the
B.
C.
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facial nerve
Main trunk of the
extratemporal facial nerve
Facial nerve and its
surrounding connective
tissue at the stylomastoid
foramen
X. Gao et al.
Fig. 8.20 Dissection of the facial nerve at the stylomastoid foramen
level (right)
The connective tissue surrounding the stylomastoid foramen is tightly
connected to the facial nerve and contains vasa vasorum. It can be used
to x the facial nerve in the parotid and protect its blood supply.
Therefore, the facial nerve at the level of the stylomastoid foramen and
the attached soft tissue should be dissected and re-
routed anteriorly
together
Instruments: ophthalmic scissors, ophthalmic forceps
A. Rerouted part of the facial
nerve
B. Fallopian canal (the
remaining part)
C. Stylomastoid soft tissues
are used to fix the facial
nerve
D. Soft tissues surrounding
the stylomastoid foramen
are fixed in the anterior
wall of the cavity
Fig. 8.21 Rerouting of the facial nerve (right)
Transfer the tympanic segment of the facial nerve to the newly formed
bony groove anterolateral to the epitympanum. A tunnel is created in
the tissues of the parotid gland, the mastoid segment of the facial nerve
is transferred to the soft tissue tunnel, and the facial nerve is xed to the
anterior wall of the cavity using sutures. Then the soft tissues surround-
ing the facial nerve at the level of the stylomastoid foramen are sutured
to the soft tissues of the anterior wall of the cavity, and anterior rerouting of the facial nerve is completed
Hints: (1) Do not penetrate or suture the facial nerve. (2) Ensure that
the rerouted facial nerve is tension-free
Instruments: needle holder, round suture needle, suture
A. Rerouted part of the
facial nerve
B.
C. Styloid process
D.
E.
8 Infratemporal Fossa Approach
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217
A. Rerouted part of the facial
nerve
B. Jugular bulb
C. Styloid process
Fig. 8.22 Removing the fallopian canal and freeing the styloid process
(right)
The remaining part of the fallopian canal is removed; the styloid process is explored with ophthalmic scissors; the bone in front of the stylo-
Main trunk of the
extratemporal facial nerve
Jugular bulb
Sigmoid sinus
mastoid foramen is drilled away with a medium-sized cutting bur; the
root of the styloid process can be seen; the muscles of the styloid are
resected and the styloid process is freed
Instruments: ophthalmic scissors, cutting bur
Fig. 8.23 Resection of the styloid process (right)
The freed styloid process is being held by non- toothed forceps; the
bone marrow cavity is clearly visible
Instruments: non-toothed forceps
218
A. Remaining part of the
B.
C.
D. Round window niche
E.
F.
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Eustachian tube
Horizontal segment of the
internal carotid artery
Vertical segment of the
internal carotid artery
Lateral semicircular canal
Posterior semicircular canal
X. Gao et al.
Fig. 8.24 Internal carotid artery canal (right)
The internal carotid artery enters the canal in the petrous portion of the
temporal bone, curving and continuing as the horizontal segment
anteroinferior to the cochlea, exiting the petrous bone anterior to the
foramen lacerum, and then it curves superiorly on its way to the cavern-
ous sinus. After removing the shell of bone anteroinferior to the cochlea
and inferior to the Eustachian tube, the internal carotid artery is clearly
visible
Instruments: medium-sized diamond burs
8 Infratemporal Fossa Approach
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219
A. Middle cranial fossa dura
B. Horizontal segment of the
internal carotid artery
C. Promontory
D. Jugular bulb
E. Internal jugular vein
Fig. 8.25 Horizontal segment of the internal carotid artery (right)
The bone anterosuperior to the horizontal segment of the internal
carotid artery is removed with a medium-sized diamond bur to expose
that section of the artery. Hints: (1) The cochlea is closely related to the
internal carotid artery; to avoid unnecessary opening of the cochlea,
care should be taken not to drill the bone posterior to the internal
carotid artery. (2) The horizontal segment of the internal carotid artery
and the middle cranial fossa dura are separated by only a thin bony
shell. To avoid injuring the middle fossa dura, drilling of the area superior to the horizontal segment of the internal carotid artery must be
carried out very carefully. (3) The thin plate of bone separating the
Eustachian tube from the internal carotid artery may be dehiscent for
up to 5mm in 2% of cases
Instruments: medium-sized diamond burs
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