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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4368_Библиотеки_им_академика_М_И_Перельмана
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Clin. car.
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Planum
Limbus dura
Sella
CR
Endoscopic Transtuberculum Transplanum Approach
Fig. 10.2 Clival recess (CR) is
seen inferior to the sellar fl oor. The
exposure of the clival dura is not
necessary for this approach. The
asterisk denotes the position of the
medial opticocarotid recess at the
lateral aspect of the tuberculum. Clin.
car., clinoidal carotid artery; LOCR,
lateral opticocarotid recess; Op.
Op. prom.
*
prom., optic prominence.
that these septations can lead one off the midline to
the paraclival or clinoidal carotid artery. Bone overlying
the sella and the chiasmatic sulcus is eggshelled using a
coarse diamond 4-mm burr (Fig. 10.2).
The thinned-down bone between the limbus dura
and the tubercular strut is gently dissected off while
maintaining the integrity of the dura. Standard endonasal transsphenoidal landmarks can again be appreciated (Fig. 10.3). The removal of the bone at this
stage clearly shows the thickened dural fold (limbus
dura) overlying the limbus sphenoidale. The tuberculum strut is carefully thinned down prior to its subsequent removal (Fig. 10.4). Lateral end of this strut
corresponds to the medial opticocarotid recess which
marks the transition between the paraclinoidal carotid
and the supraclinoidal carotid artery. At this stage, location of the superior intercavernous sinus can be seen.
The anatomic relationships from caudal to rostral (relevant to this approach) are sella, diaphragm, superior
intercavernous sinus, tuberculum, chiasmatic sulcus,
limbus dura, and finally the dura of the planum (not
exposed here) (Fig. 10.5). The next step represents further removal of the bone to expose the planum dura.
The bone overlying the OC along its medial aspect and
the roof can be seen. Bone overlying the clinoidal carotid artery is thinned down and then carefully dissected
off (Fig. 10.6).
Fig. 10.7 shows relevant anatomy of the OC and
the technique for maximal endoscopic endonasal OC
decompression.
10.1.1 General Information
In a standard transplanum/transtuberculum approach,
the limbus sphenoidale is drilled along with further removal of the medial aspect of the anterior root of the lesser
wing of the sphenoid bone (planum sphenoidale) forming
the roof of the OC. In this step, as illustrated, a 270-degree
decompression of the osseous OC has been performed to
enable (after dural cuts) exposure of both the preforaminal and the intracanalicular segments of the optic nerve.
This step requires a thorough understanding of the anatomy of the OC, its osseous, and vascular relationships so
that it can be performed in cases with tuberculum sellae
meningiomas with true OCI, as defined by the presence
of tumor in the osseous OC. Intraoperatively and in anatomic dissections, it becomes progressively difficult to
drill the superolateral aspects of the OC (formed by the
lateral part of the anterior root of the lesser wing of the
sphenoid). In terms of the involvement of the OC, using
the lateral opticocarotid recess (LOCR), we prefer to make
a distinction between the preforaminal ON, roofed by the
falciform ligament from the intracanalicular segment in
the osseous OC. This facilitates the preoperative surgical
strategy (involving examination of preoperative images
in relation to the LOCR) regarding the extent of required
OC decompression and dural opening so that, when required, early intraoperative decompression of the OC can
be performed. Although some of the relevant details are
presented here, we refer the readers to our publication for
a more detailed understanding of this area.
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Endoscopic Transtuberculum Transplanum Approach
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Planum
Limbus dura
Fig. 10.3 Standard endonasal
landmarks can be visualized. Chias.
sulc., chiasmatic sulcus; Clin. car.,
clinoidal carotid artery; CR, clival
recess; LOCR, lateral opticocarotid
recess; Op. prom., optic prominence.
Op. prom.
LOCR
Clin. car.
Chias. sulc.
Sella
CR
Limbus dura
Fig. 10.4 The eggshelled
tuberculum strut (Tuberc. strut)
can be seen. Chias. sulc., chiasmatic
sulcus; Clin. car., clinoidal carotid
artery; CR, clival recess.
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Clin. car.
Chias. sulc.
Tuberc. strut
Sella
CR
Endoscopic Transtuberculum Transplanum Approach
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Clin. car.
Limbus dura
Chias. sulc.
Fig. 10.5 Important anatomic
structures of relevance to this
approach are demonstrated
rostrocaudally. Chias. sulc., chiasmatic
sulcus; Clin. car., clinoidal carotid;
CR, clival recess; SIS, superior
intercavernous sinus; Tuberc.,
tuberculum.
Tuberc.
SIS
Sella
CR
Clin. car.
Tuberc.
Fig. 10.6 Exposure of the planum
dura. Chias. sulc., chiasmatic sulcus;
Clin. car., clinoidal carotid artery;
CR, clival recess; LOCR, lateral
opticocarotid recess; Tuberc.,
tuberculum.
Planum dura
Limbus dura
Chias. sulc.
LOCR
SIS
Sella
CR
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Planum dura
Limbus dura
Clin. car.
Sella
Fig. 10.7 Relevant anatomy of the
optic canal and maximal endoscopic
endonasal optic canal decompression.
Clin. car., clinoidal carotid artery;
LOCR, lateral opticocarotid recess.
LOCR
10.1.2 Boundaries of the Optic
Canal and Distinction of Its Segments
The true osseous OC with the intracanalicular segment
of the ON has circumferential bony covering around it.
Accordingly, its boundaries are medially the body of the
sphenoid bone and inferiorly the optic strut and the adjacent part of the body of the sphenoid bone, with the
roof being formed by the anterior root of the lesser wing
of sphenoid bone. Endonasally, the osseous OC (Fig. 10.7,
shaded yellow area between the dotted lines) approximates to the anteroposterior length of the LOCR (~6 mm).
Endonasally, the preforaminal segment can be indirectly
estimated using the anterolateral fold of the limbus just
medial to the LOCR (Fig. 10.7, the length between the
yellow arrow and the posterior dotted curved line or the
posterior aspect of the LOCR). The yellow arrow denotes
the point of posteromedial attachment of the falciform
ligament and represents the area through which the endonasal dural incision should be directed to detach the
falciform ligament.
10.1.3 Surgical Technique for
Maximal Endoscopic Endonasal
Optic Canal Decompression
The medial bony wall is removed with a 1-mm Kerrison
rongeur or a microdissector (Fig. 10.7). The exposure of
the intracanalicular ON surrounded by the optic sheath
is followed anteriorly to the orbital apex. To achieve up
to 270-degree decompression of the intracanalicular ON,
the medial wall, floor, and roof of the OC also need to be
thinned and subsequently removed. The lower margin
of the OC, the body of sphenoid bone adjacent to optic
strut, can be drilled with a 2-mm drill bit. Removal of
the superolateral aspect of the OC to increase the extent
of bony decompression to up to 270 degrees increases
risk of injury to the ON, so employment of a meticulous
technique by an experienced skull base surgeon is necessary to minimize this risk. The superior aspect of the
OC is thinned using the 2-mm drill under copious irrigation. This is followed by positioning of a 1- or 2-mm
Kerrison rongeur or dissectors carefully between the anterior cranial fossa dura and the OC to dissect off the thin
bone and unroof the OC, gently compressing superiorly
on the anterior skull base dura but not inferiorly into the
dura surrounding the OC. It is critically important that
the Kerrison rongeur is placed outside the OC in a reverse fashion. The base of anterior clinoid and the lateral
aspect of the optic strut forming the lateral margin and
the lateral part of the floor of the OC, respectively, cannot be removed safely via an endonasal approach. The
extent of bony decompression is adjusted depending
upon the preoperative imaging studies and the extent of
the involvement of the OC. Prior to any endonasal tumor
manipulation, patients with true OCI should undergo at
least removal of the medial wall of the OC to just beyond the anterior most aspect of the LOCR with further
bony removal depending upon the pattern of OCI. Similarly, patients with extension of tumor limited to the
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Limbus dura
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Planum dura
2
Endoscopic Transtuberculum Transplanum Approach
Fig. 10.8 Schematic representation
of the dural incision on the left side
1
4
OC
to expose the preforaminal and the
intracanalicular segments of the optic
nerve. See text for details. Clin. car.,
clinoidal carotid artery; CR, clival
recess; LOCR, lateral opticocarotid
recess; OC, optic canal.
3
CR
preforaminal segment of the ON can be identified with
respect to the LOCR using the preoperative imaging. Intraoperatively in these cases, bony drilling does not need
to involve the OC and can be stopped at or just beyond
the posterior most aspect of the LOCR obviating any potential risk of injury to the intracanalicular ON.
Next pertinent step involves the endonasal dural incision. This is demonstrated in a schematic representation
of the dural incision on the left side to expose the preforaminal and the intracanalicular segments of the optic
nerve (Fig. 10.8). The incision (Figs. 10.8 and 10.9) starts
in the upper part of the sella and continues superiorly
across the superior intercavernous sinus, tuberculum
dura, and the chiasmatic sulcus before turning laterally
across the limbus and planum dura.
1
The dural flap is
now reflected laterally to identify the origin of the ophthalmic artery. To increase the mobility of this dural leaf,
two further diaphragmatic cuts
directed posteriorly toward the infundibulum
2,3
are made, with the first
2
and the
second performed laterally toward the distal dural ring
(or the medial opticocarotid recess) while being cautious
about the carotid and the ophthalmic arteries.
3
This may
suffice for accessing the tumor around the cisternal or
preforaminal segment of the ON. The intracanalicular
dura around the OC
4
may be opened along its superior aspect from a medial to lateral direction to access intracanalicular tumor.
After completion of the first cut, the dura is reflected downwards to check the origin of the ophthalmic
artery from the supraclinoidal carotid artery beyond
the distal ring prior to carrying out the diaphragmatic cuts (Fig. 10.10). A medially looping ophthalmic
LOCR
Clin. car.
artery should be checked for to prevent potential injury. The dura of the anterior cranial fossa is then reflected upwards to expose the detached medial end of
the falciform ligament with exposure of the underlying
preforaminal optic nerve. Cisternal segment of the optic
nerve can also be seen (Fig. 10.11). The corresponding
intracranial view for the endoscopic view is shown in
the next illustration (Fig. 10.12). Regional anatomy can
be appreciated in addition to the visualization of the
detached medial aspect of the falciform ligament with
underlying preforaminal optic nerve. After completion
of the diaphragmatic cuts and division of the dural
sheath around the ON as far as the orbital apex, exposure of the intracranial and intracanalicular segments of
the optic nerve is achieved (Fig. 10.13). The structures
in the suprasellar infrachiasmatic space are represented
after opening of the dura overlying the chiasmatic sulcus. The superior hypophyseal arteries coming off the
medial aspect of the supraclinoidal carotid artery and
supplying the undersurface of the chiasm and pituitary
stalk can be clearly seen. These vessels should be carefully preserved in operative approaches directed toward
this region (Fig. 10.14).
The dura in the planum region is finally opened to
expose the gyrus rectus and other suprasellar structures,
including the A1 and A2 segments of the anterior cerebral
artery and the anterior communicating artery. Again
superior hypophyseal arteries supplying the underside of
the chiasm and pituitary stalk can be seen. The proximal
cisternal optic nerve can be visualized. Reconstruction
of the skull base defect can be performed using a
vascularized nasoseptal flap (Fig. 10.15).
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Planum dura
Limbus dura
OC
Fig. 10.9 Incision corresponding to
Abhinav et al1 in the schema has been
made in an anatomic specimen on
the right side. Chias. sulc., chiasmatic
sulcus; Clin. car., clinoidal carotid;
CR, clival recess; LOCR, lateral
opticocarotid recess; OC, optic canal.
LOCR
Clin car
Opth. a.
ON.
Chias. sulc.
Sella
CR
Fig. 10.10 Visualizing the origin
of the ophthalmic artery (Opth. a.).
Superior hypophyseal artery (Sup.
hypoph. a.) originating from the
medial aspect of the supraclinoidal
carotid artery can be seen. Clin. car.,
clinoidal carotid; CR, clival recess;
LOCR, lateral opticocarotid recess;
ON, optic nerve.
Sup. hypoph. a.
LOCR
Clin. car.
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Sella
CR
Falc. lig
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Opth. a.
Preforam. ON
Cist. ON
Endoscopic Transtuberculum Transplanum Approach
Fig. 10.11 Detached medial end of
the falciform ligament (Falc. lig) can
be seen overlying the preforaminal
optic nerve (Preforam. ON). Cist. ON,
cisternal segment of the optic nerve;
Clin. car., clinoidal carotid; CR, clival
recess; Dist. ring, distal ring; LOCR,
lateral opticocarotid recess; Sup.
hypoph. a., superior hypophyseal
artery; Supraclin. car., supraclinoidal
Sup. hypoph. a.
carotid artery.
LOCR
Chias. sulc.
Clin. car.
Planum dura
Limbus dura
Dist. ring
Preforam. ON
Supraclin. car.
Sella
CR
Fig. 10.12 Intracranial view for
the endoscopic view as presented
in the previous figure. Chias.
sulc., chiasmatic sulcus; Cist. ON.,
cisternal optic nerve; Pit. stalk,
pituitary stalk; Preforam. ON.,
preforaminal optic nerve.
Pit. stalk
Chiasm
Cist. ON
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Preforam. ON
Cist. ON.
LOCR
Fig. 10.13 Endonasal view on the
right side after completion of the
diaphragmatic cuts and division of
the dural sheath around the ON as
far as the orbital apex to expose
the intracranial and intracanalicular
segments of the optic nerve. Cist.
ON., cisternal optic nerve; Clin. car.,
clinoidal carotid; CR, clival recess;
LOCR, lateral opticocarotid recess; Pit.
stalk, pituitary stalk; Preforam. ON.,
preforaminal optic nerve.
Pit. stalk
Clin. car.
ON
Supraclin. car.
Sup. hypoph. a.
Sella
CR
Planum dura
Chiasm
Pit. stalk
Limbus dura
Fig. 10.14 Structures in the
suprasellar infrachiasmatic space
after opening of the dura overlying
the chiasmatic sulcus. ON, optic
nerve; Pit. stalk, pituitary stalk; Pit.
gland, pituitary gland; Sup. hypoph.
a., superior hypophyseal arteries;
Supraclin. car., supraclinoidal
carotid artery.
10.2 Case Example
A 57-year-old woman presented with severe left optic
neuropathy (20/800) and bitemporal hemianopsia
(Fig. 10.16). Intraoperative images and postoperative
102
Pit. gland
magnetic resonance scan demonstrate complete resection
of the suprasellar lesion performed via the endonasal
approach. Postoperatively, she had significant improvement
in the left eye visual function (20/80) with an almost
complete resolution of the field defect on the left side.
Gyrus rectus
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ACA
Sup. hypoph. a.
Acom a
Orbitofront. a.
Pit. stalk
Endoscopic Transtuberculum Transplanum Approach
Fig. 10.15 Dura in the planum
region opened to expose the gyrus
rectus and other suprasellar structures
including the A1 and A2 segments of
the anterior cerebral artery (ACA) and
the anterior communicating artery
(Acom A.). Cist. ON., cisternal optic
nerve; Orbitofront. a., orbitofrontal
artery; Pcom a., posterior
communicating artery ; Pit. stalk,
pituitary stalk; Sup. hypoph.
a, superior hypophyseal arteries.
Cist. ON.
Pcom a.
a b
d e
Fig. 10.16 (a–c) These MR images (T1 with contrast; coronal) demonstrate a tuberculum sella meningioma in a 57-year-old with
evidence of left optic canal invasion and compromised visual function. (d–f) Intraoperative and the postoperative images (T1 with
contrast) demonstrate complete resection of the tumor with preservation of the critical neurovascular structures.
c
f
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Acknowledgment
We would like to acknowledge Dr. Wei Hsin Wang at the
Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taiwan and the School of
Medicine, National Yang-Ming University, Taipei, Taiwan
for his technical help and contribution toward a few of
the anatomic dissection pictures.
References
1. Abhinav K, Acosta Y, Wang WH, et al. Endoscopic endonasal
approach to the optic canal: anatomic considerations and surgical
relevance. Neurosurgery 2015;11(Suppl 3):431–445, discussion
445–446
2. Kassam A, Snyderman CH, Mintz A, Gardner P, Carrau RL. Expanded endonasal approach: the rostrocaudal axis. Part I. Crista galli to
the sella turcica. Neurosurg Focus 2005;19(1):E3
3. Liu JK, Christiano LD, Patel SK, Tubbs RS, Eloy JA. Surgical nuances
for removal of tuberculum sellae meningiomas with optic canal
involvement using the endoscopic endonasal extended transsphenoidal transplanum transtuberculum approach. Neurosurg Focus
2011;30(5):E2
4. Koutourousiou M, Fernandez-Miranda JC, Stefko ST, Wang EW,
Snyderman CH, Gardner PA. Endoscopic endonasal surgery for suprasellar meningiomas: experience with 75 patients. J Neurosurg
2014;120(6):1326–1339
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