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Pituitary Gland Transposition and Retrosellar Approach
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Fig. 19.14 The pituitary stalk visible after incision of the
diaphragma sellae in an anterior-to-posterior fashion.
Fig. 19.16 Incision of the dura of the upper one-third of the
clivus in the midline, exposing the craniopharyngioma.
Fig. 19.15 Exposure of the dorsum sellae with cranial
retraction of the gland and posterior sellar dura.
Fig. 19.17 Piecemeal resection of the craniopharyngioma
using suction and scissors. The left posterior communicating
artery is visualized.
were released bilaterally, and the sellar dura was incised
bilaterally in an anterior-to-posterior fashion, taking care
to leave the posterior sellar dura undisturbed. The gland
and posterior sellar dura were then retracted cranially,
exposing the dorsum sellae (Fig. 19.15). This was then
drilled completely, and the dura of this upper one-third
of the clivus was incised in the midline (Fig. 19.16), exposing the tumor. The mass was removed in piecemeal
fashion (Fig. 19.17) until all visible tumors were resected.
A weakened pituitary stalk was preserved, and the skull
base was repaired with the nasoseptal flap. Postoperatively, she experienced no decline in cranial nerve
or visual function. She required permanent hormone
replacement therapy as well as oral desmopressin for
persistent diabetes insipidus. The pituitary transposition
has an inherent risk of pituitary dysfunction; however, in
the present case, the decline in the already poor pituitary
function was most likely related to the resection of the
craniopharyngioma away from the friable pituitary stalk.
Fifty-two-month postoperative postcontrast T1-weighted sagittal (Fig. 19.18) and coronal (Fig. 19.19) MRI of the
brain demonstrate gross total resection without evidence
of recurrence.
19.4 Complications
Complications specifically related to the transposition of
the pituitary gland correspond to the anatomic structures
involved in the dissection. Prior to mobilizing the gland,
the diaphragma sellae must be released anteriorly. Doing
so places the arachnoid of the suprasellar cistern at risk of
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Fig. 19.18 Postcontrast T1-weighted sagittal MRI of the
brain in the case example patient 52 months postoperatively
demonstrating gross total resection without evidence of
recurrence.
Fig. 19.19 Postcontrast T1-weighted coronal MRI of the
brain in the case example patient 52 months postoperatively
demonstrating gross total resection without evidence of
recurrence.
being inadvertently lacerated and causing significant cerebrospinal fluid leak. Next, while elevating the pituitary
gland, the mechanical disturbance may lead to dysfunction
of the anterior and/or posterior gland, as can disruption of
the venous drainage if the posterior dural intercavernous
sinus is injured. In a series of 10 patients in whom attention was not paid to preserving the posterior intercavernous
sinus, 1 of the 10 developed both new panhypopituitarism
and diabetes insipidus (2 others had preoperative panhypopituitarism that did not resolve, and 1 of these 2 had preoperative and postoperative diabetes insipidus as well; 7 had
normal gland function preoperatively and postoperatively).
One alternative to reduce the risk of pituitary dysfunction
has been the utilization of hemi-pituitary transposition,
where one of the sides of the pituitary gland is kept attached to the medial wall of the cavernous sinus.
The intercavernous sinuses, cavernous sinus, and,
more posteriorly, the basilar plexus all may bleed profusely, and the surgeon must anticipate the potential for
torrential bleeding and have a plan ready to address it.
Drilling the clivus or over the cavernous sinuses places the paraclival and parasellar segments of the ICA at
risk of injury, and we advocate performing EEA surgery
only in facilities with an available neuroendovascular
interventional radiologist.
5
After transposing the gland
and fully resecting the clivus, the surgeon is afforded
generous access to the prepontine and interpeduncular
cisterns. Given the relative difficulty with working with
angled endoscopes used to view the lateral and superior
aspects of these regions, there exists the potential for
mechanical injury to the critical neurovascular structures such as the brainstem, posterior circulation, and
cranial nerves III, IV, and VI.
19.5 Tips and Tricks
• Know your anatomy! In the words of one of the senior
authors (R. C.), “Your eyes will not see what your brain
does not know.”
• Understanding the dural anatomy in the sellar region
is critical to avoid injury to the structures of the cavernous sinus, inferior hypophyseal artery, and pituitary
gland itself.
• One should leave the posterior dura intact to maintain
the integrity of the gland and glandular drainage, par-
3
ticularly for the neurohypophysis.
• When incising the dural intercavernous sinuses or
avulsing microscopic bridging veins with dural elevation, one must always have an ample amount of hemostatic agent ready to address venous bleeding.
• Regardless of which agent is used, measures to reduce
venous pressure such as chemical paralysis and head of
bed elevation are effective in reducing venous pressure
and bleeding.
• Do not attempt to fully remove the posterior clinoid
processes while removing the dorsum sellae. Their
ligamentous attachments, particularly to the anterior
clinoid process via the interclinoid ligament, place the
ICA at risk of laceration if one attempts to remove them.
Rather, they can be disconnected from the dorsum sellae with the drill at their connection (or “shoulder”)
and simply left in situ, as they do not guard access to
the interpeduncular and prepontine cisterns.
• Finally, we advocate particular caution in utilizing an
EEA for resection of epidermoid tumors of this region.
Any residual avascular material elaborated by the epithelium serves as a nidus for bacterial infection and
6
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Pituitary Gland Transposition and Retrosellar Approach
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may be seeded with exposure to the nasal cavity during
an EEA. Antibiotics are poorly effective at sterilizing the
infected avascular keratin; so, unless a total resection is
anticipated, a transcranial approach may be more prudent than a transnasal one.
References
1. Hadad G, Bassagasteguy L, Carrau RL, et al. A novel reconstructive technique after endoscopic expanded endonasal
approaches: vascular pedicle nasoseptal flap. Laryngoscope
2006;116(10):1882–1886
2. Fernandez-Miranda JC, Prevedello DM, Madhok R, et al. Sphenoid septations and their relationship with internal carotid arteries: anatomical and radiological study. Laryngoscope
2009;119(10):1893–1896
3. Kassam AB, Prevedello DM, Thomas A, et al. Endoscopic endonasal pituitary transposition for a transdorsum sellae approach to
the interpeduncular cistern. Neurosurgery 2008;62(3, Suppl 1):
57–72, discussion 72–74
4. Kassam AB, Gardner PA, Snyderman CH, Carrau RL, Mintz AH,
Prevedello DM. Expanded endonasal approach, a fully endoscopic transnasal approach for the resection of midline suprasellar
craniopharyngiomas: a new classification based on the
infundibulum. J Neurosurg 2008;108(4):715–728
5. Labib MA, Prevedello DM, Carrau R, et al. A road map to the internal carotid artery in expanded endoscopic endonasal approaches to the ventral cranial base. Neurosurgery 2014;10(Suppl 3):
448–471, discussion 471
6. Campero A, Campero AA, Martins C, Yasuda A, Rhoton AL Jr.
Surgical anatomy of the dural walls of the cavernous sinus. J Clin
Neurosci 2010;17(6):746–750
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0
Chapter 20
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20.1 Indications 210
Transclival Approach
20.2 Surgical Steps 210
20.3 Case Examples 212
20.4 Complications 214
20.5 Tips and Tricks 214
Transclival Approach
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20 Transclival Approach
Joaquim Enseñat, Elena D’avella, Isam Alobid, Matteo de Notaris, Alberto Prats-Galino
Introduction
The endoscopic endonasal approach to the clivus represents an increasingly important surgical corridor for
skull base surgery. It provides surgical access to the ventral midline skull base of the middle and posterior fossa.
Although the approach is mostly used for removal of
chordomas, the same surgical principles can be applied
to a variety of pathologies. Cadaveric studies have documented the extensive exposure through the endoscopic
endonasal transclival approach, and description of surgical technique have supported the successful treatment
of complex skull base pathologies. The anatomic limits of
clivectomy are the floor of the sella superiorly, the foramen magnum inferiorly, and the internal carotid artery
laterally. Removal of the clival bone can be limited to a
transdorsum approach for exposure of the interpeduncular fossa or can be extended to the lower clivus for
tumors of the foramen magnum region. Important anatomic landmarks during the approach are the sella, the
opticocarotid recess, the dorsum sellae, the vidian nerve,
and the paraclival carotid artery. Skull base reconstruction is performed with a multilayered technique together
with a pedicled nasoseptal flap. Major complications of
the transclival approach are cerebrospinal fluid (CSF) leak
and damage to the internal carotid artery, vertebrobasilar
complex, and abducens nerve.
Table 20.1 Anatomic landmarks to be exposed for each surgical step during the endoscopic endonasal transclival approach
20.1 Indications
The endoscopic endonasal transclival approach is used for
lesions involving the clivus or the retroclival region:
• Clival chordomas.
• Chondrosarcomas.
• Cholesterol granulomas.
• Craniopharyngiomas in the retrosellar area.
• Clival meningiomas.
• Vascular lesions (brainstem cavernomas, posterior cir-
culation aneurysms).
• Other clival lesions (mucoceles, ossifying fibromas, os-
teogenic sarcomas, adenocarcinomas, plasmacytomas,
metastases, fibrous dysplasia, neuroenteric cysts).
20.2 Surgical Steps
20.2.1 Patient Positioning
The patient is placed in a supine position with the head
fixed in a three-pin Mayfield holder and elevated 20 to 30
degrees, slightly rotated toward the side of the surgeon
and slightly more flexed than for a common endoscopic
procedure for a sellar lesion, to improve the field of view
toward the clivus. Anatomic landmarks of the following
steps can be consulted in Table 20.1.
1–10
Nasal phase Sphenoidal phase Transclival approach Intradural exposure
Middle turbinate Anterior wall of sphenoid sinus Dorsum sellae Floor of III ventricle
Maxillary ostium Sphenoid fl oor Vomer–sphenoid junction Oculomotor nerve
Sphenopalatine artery Clival recess Pter ygoid plate Superior cerebellar arter y
Sphenoid rostrum Medial opticocarotid
recess
Clivocarotid
protuberance
Pterygoid canal Posterior cerebral artery
Vidian nerve Posterior
communicating artery
Petrous internal carotid artery Cerebral peduncle
Rhinopharyngeal mucosa Trochlear nerve
Longus capitis muscle Basilar artery
Longus colli muscle Ventral surface of brainstem
Foramen magnum Abducens nerve
Vertebral arter y
Trigeminal nerve
Anteroinferior cerebellar artery
Lower cranial nerves
Jugular foramen
Posterior inferior cerebellar arter y
Hypoglossal nerve
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20.2.2 Nasal and Sphenoidal Steps
A standard nasal access set used in endoscopic paranasal
sinus surgery is used for the initial and extradural part
of the procedure. Resection of one, usually the right, or
both middle turbinates is performed. A large middle meatal antrostomy can be created to store the nasal septal
flap and keep it safe during the procedure. The nasoseptal flap, pedicled at the sphenopalatine bundle, is created
on one side following the Hadad technique
11
(see Chapter
34). The posterior half of the nasal septum is removed to
widely expose the rostrum (see Chapter 5). The sphenoid
rostrum and anterior wall of sphenoid sinus are removed.
The sphenoid floor is drilled flush with the clival recess
and the clival bone is exposed. By drilling the lateral recess of the sphenoid, the medial and lateral opticocarotid
recesses and the clivocarotid protuberances are visualized and are important surgical landmarks for the rest of
the procedure (Fig. 20.1).
20.2.3 Transclival Approach
At this point, the tumor will often be visible, especially
if the clivus is eroded anteriorly. When the lesion is
not visible, its location is confirmed by intraoperative
navigation, and drilling of the upper clivus can be
started. Removal of the clival bone is initiated with
a diamond burr drill and continued carefully with a
Kerrison punch.
In cases of tumor extension to the upper clivus only
(sphenoidal segment of the clivus), the expanded endonasal approach consists of removal of upper part of the
clivus and the dorsum sellae.
For lesions extending to the foramen magnum region,
bone removal should be extended to the lower part of the
clivus. The vomer–sphenoid junction, the medial pterygoid plate, and vidian canal are identified in a medial to
lateral direction (Fig. 20.2). The vomer and inferior wall
of sphenoid sinus are removed.
The vidian nerve in the pterygoid canal can be identified and the canal is drilled along its inferior circumference until the petrous internal carotid artery at the
lacerum segment is encountered (Fig. 20.3). Then, the
rhinopharyngeal mucosa is dissected and the longus
capitis and longus colli muscles are lateralized (Fig. 20.4).
The limits of clivectomy are the floor of the sella
superiorly, the foramen magnum inferiorly, and the
internal carotid artery laterally (Fig. 20.5).
ICAs
ICAc
ET
Fig. 20.1 By drilling the lateral recess of the sphenoid, the
medial opticocarotid recess and clivocarotid protuberances are
visualized. dm, dura mater; ET, eustachian tube; ICAc, clival
internal carotid artery; ICAs: sellar internal carotid artery; MT:
middle turbinate; PG: pituitary gland.
PG
dm
C1
ICAs
ICAc
MT
ET
ss
iwsphs
VSJ
VC
V
Fig. 20.2 For lesions extending to the foramen magnum
region, bony removal should be extended to the lower part of
the clivus. The vomer–sphenoid junction, the pterygoid plate,
and vidian canal are identifi ed in a medial to lateral direction.
iwsphs, inferior wall of sphenoid sinus; SS, sphenoidal sinus; V,
vomer; VC, vidian canal; VSJ, vomer–sphenoid junction.
PG
C
Fig. 20.3 The vidian nerve in the pterygoid canal can be
identifi ed (blue dots) and the canal is drilled until the petrous
internal carotid artery at the lacerum segment is encountered.
C, clivus; Co, choana; FL, foramen lacerum; ICAc, clival internal
carotid artery; ICAs, sellar internal carotid artery; PG, pituitary
gland; VN, vidian nerve; VSJ, vomer–sphenoid junction.
ICAs
ICAc
VN
FL
VSJ
Co
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C
SF
iwsphs
RPhx
ET
Fig. 20.4 The rhinopharyngeal mucosa is dissected and the
longus capitis and longus colli muscles are lateralized. C, clivus;
ET, eustachian tube; iwsphs, inferior wall of sphenoid sinus;
RPhx, rhinopharyngeal mucosa.
ET
20.2.4 Intradural Exposure
A second set of low-profile instruments and specially
designed bipolar forceps are used for the intradural
work. Dura opening should be performed at the midline,
after locating the position of the internal carotid arteries
on both sides and also basilar artery, with image
guidance and micro-Doppler (Fig. 20.6). Then intradural
exploration can be started (Figs. 20.7a, b and 20.8a, b).
The tumor is removed with the same bimanual technique
used during microscopic resection, but with a significantly
wider field of vision under endoscopic visualization.
ICA
ICA
FM
Fig. 20.5 The limits of clivectomy are the fl oor of the sella
superiorly, the foramen magnum inferiorly, and the internal
carotid artery laterally. FM, foramen magnum; ICA, internal
carotid artery; SF, sellar fl oor.
PG
ICAc
ICAc
BA
20.2.5 Skull Base Reconstruction
We favor a multilayer reconstruction. Fat tissue is placed
intradurally. A layer of cadaveric fascia lata is placed
intradurally in an inlay fashion. A second layer of fascia
lata is placed extradurally (onlay) to cover the dura and
bone edges. The grafts are covered with the vascularized
nasal septal flap. Spongostan is placed to apply pressure
and to hold the repair in place.
20.3 Case Examples
20.3.1 Case 1
A 52-year-old woman presented with diplopia. Neurologic
examination revealed right abducens nerve palsy. Magnetic resonance imaging showed a petroclival chordoma.
Gross total resection was obtained using an endonasal
endoscopic transclival approach. Intraoperative images
show drilling of the vidian canal and its relation with the
petrous internal carotid artery, tumor, and clivus bone
(Fig. 20.9a, b).
dm
Fig. 20.6 Dura opening at the midline, after locating the
position of the internal carotid arteries on both sides and
basilar artery. BA, basilar artery; dm, dura mater; ICAc, clival
internal carotid artery; PG, pituitary gland.
20.3.2 Case 2
A 74-year-old woman was admitted with a diffuse subarachnoid hemorrhage associated with intraventricular
hemorrhage and a starting hydrocephalus. Cerebral angiography revealed a 1.2-mm aneurysm arising at the origin
of the right posterior inferior cerebellar artery. The aneurysm was considered unsuitable for selective coil embolization. With the use of an extended endoscopic endonasal
transclival approach, the aneurysm was accurately reached
endoscopically and successfully clipped (Fig. 20.10).
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III cn
3th V
P
PCA
SCA
VI cn
CP
BA
P
III cn
MB
PCA
III cn
BA
SCA
ab
Fig. 20.7 Intradural exposure at the upper retroclival region. (a–b) Interpeduncular fossa and ventral pons are visualized. 3rd V, fl oor
of the third ventricle; BA, basilar artery; CP, cerebral peduncle; III cn, oculomotor nerve; IV cn, trochlear nerve; MB, mammillary body;
mTL, mesial temporal lobe; P, pons; PCA, posterior cerebral artery; SCA, superior cerebellar artery.
BA
mTL
IV cn
V cn
AICA
P VI cn
VA
MO
a
Fig. 20.8 Intradural exposure of the inferior retroclival region. (a) Ventral surface of pons and medulla oblongata, basilar artery, and
vertebral arteries are visible at midline; inferiorly, the origin of the posteroinferior cerebellar artery, the inferior cranial nerves, and
rootlets of the hypoglossal nerve are visualized. (b) Superolaterally, the cisternal segment of the abducens nerve and the origin of
the trigeminal nerve are exposed. AICA, anterior inferior cerebellar artery; BA, basilar artery; LCN, lower cranial nerves ; MO, medulla
oblongata; P, pons; PICA, posterior inferior cerebellar artery; VA, vertebral artery; V cn, trigeminal nerve; VI cn, abducens nerve; XII cn,
hypoglossal nerve.
VA
LCN
PICA
XII CN
b
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ICAc
ICAp
VN
a b
Fig. 20.9 Intraoperative images showing (a) the identifi cation of vidian nerve and petrous internal carotid artery, and (b) removal
of the clival portion of the tumor, medially to the internal carotid artery. ClivalD, clival dura; ICAc, clival internal carotid artery; ICAp,
petrous internal carotid artery; VN, vidian nerve.
Clivus
Tumor
ClivalD
During the endoscopic endonasal approach to the mid-
dle clivus, injury to the abducens nerve is possible.
AICA
R
With this approach, the cisternal segment of the nerve in
its mediolateral ascending trajectory is entirely exposed.
The vertebrobasilar junction provides a reliable landmark
marking the origin of both abducens nerves. During a
PICA
R
transclival approach, dural opening should therefore be
performed at the midline and extended laterally, because
the abducens nerve would be in its ascending cisternal
segment at least 6 mm off the midline. The interdural
VA
R
A
segment of the abducens nerve is the short portion of the
nerve that ascends between the two layers of dura that
form the walls of the inferior petrosal sinus just posterior
to the paraclival carotid, at the level of the lateral margin of
AS
the midclival approach. The lateral clival artery, branch of
the dorsal meningeal artery, can be used as a surgical reference for the interdural segment of the abducens nerve.
Fig. 20.10 An endoscopic endonasal transclival approach
was performed for a small posterior inferior cerebellar
artery aneurysm. Intraoperative image of clip placement. A,
aneurysm; AICAr, right anterior inferior cerebellar artery; AS,
aspirator; PICAr, right posterior inferior cerebellar artery; VAr,
right vertebral artery.
When the clivectomy is extended laterally, the interdural
segment of the abducens nerve is at significant risk.
The endoscopic endonasal transclival approach is associated with a high risk of CSF leak, due to the need
of a large bony and dural opening and the presence of
premesencephalic and prepontine cisterns next to the
skull base opening of the transclival approach.
11,17–20
2,6,15,16
20.4 Complications
The basilar venous plexus is situated between the two layers
of dura. It can span from the upper third of the clivus to its
entire length. The basilar plexus is connected to the paired
cavernous sinus superiorly, the inferior petrosal sinus laterally, and the marginal sinus inferiorly. Bleeding in the basilar
plexus should be managed upon dural opening.
not be cauterized safely but it is usually controlled with soft
packing using hemostatic material, such as Floseal.
Main vascular injuries during the transclival approach
concern the internal carotid arteries bilaterally and the
basilar artery, especially in patients undergoing revision
surgery after radiotherapy.
of arterial vessels to stop the arterial bleeding should
be attempted with compression by a muscle graft and
hemostatic material, such as Surgicel. Direct application
of Floseal on the arterial tear should be avoided due to the
risk of iatrogenic thrombosis. In selective cases, a vascular
clip placement might be considered.
214
1,9,13,14
Endoscopic packing
2–5,12
It can-
20.5 Tips and Tricks
The vidian nerve is an important landmark for a safe
localization of the petrous carotid artery at the foramen
lacerum. It can be identified inside the pterygoid canal
approximately 0.5 cm laterally to the vomer–sphenoid
junction. By drilling the bone inferomedially to this canal,
the surgical corridor can be widened to the level of the
petrous segment of the internal carotid artery, while reducing the risk of tearing the vessel.
sella is exposed, the most obvious and least dangerous
place to identify the carotid remains at the level of the
parasellar carotid protuberances, which are generally
clearly seen.
The ultrasound (micro-)Doppler probe is a fast, safe,
and accurate technique for localizing the internal carotid
artery, the vertebrobasilar system, and smaller vessels of
posterior circulation,
4,5,13,14
particularly when the carotid
has been displaced after partial tumor removal and navigational systems are no longer reliable.
21
However, when the
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