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ReviewSt. Marianna Med. J.
Vol. 32, pp. 219�226, 2004
Recent Advances in Surgical Approaches to Parasellar Lesions
Yoshio Taguchi, M.D.
�Received for Publication: September 15, 2004�
Key words
Surgical approaches, Parasellar lesions
Introduction
Recent advances in microsurgical instruments
and refinement of surgical techniques have made it
possible to operate the lesions situated at the medial
end of the sphenoid wing, in the third ventricle,
around the anterior tentorial hiatus, and in the
interpeduncular fossa. Although these parasellar le-
sions are commonly encountered, they may be
di$cult to expose without considerable and poten-
tially harmful brain retraction when approached by
using the conventional surgical approaches, such as
bifrontal, frontotemporal, or temporal craniotomy
developed in the era of the dawn of brain surgery.
Therefore, an alternative approach that avoids
these di$culties would be welcome in appropriate
circumstances. Jane et al.1� have refined the supraor-
bital approach originally developed by McArthur2�
in 1912 and Frazier3� in 1913. More recently, various
surgical techniques have been reported to o#er an
excellent exposure of the cranial base with minimal
brain retraction and to avoid bothersome postop-
erative complications. In the present paper, these
surgical approaches will be reviewed after learning
anatomy and pathology of the parasellar region.
Intrasellar lesions including pituitary adenomas will
be excluded because surgical approaches are quite
di#erent from the lesions described here.
Anatomy and pathology of the parasellar region
Anatomical relations of the parasellar struc-
tures are complex �Fig. 1�. The optic nerve proximal
to its entrance into the optic canal is covered by a
reflected leaf of dura, the falciform ligament, of
which length may vary from less than 1 mm to as
much as 1 cm. The relation of the optic chiasm to
the sella is an important determinant of the ease
with which the pituitary fossa may be exposed by
the trans-frontal surgical route. The normal chiasm
overlies the diaphragma sellae and the pituitary
gland. In approximately 70 percent of cases, the
chiasm is in the normal position. Of the remaining
30 percent, about half are prefixed and half
postfixed4�. The diaphragma sellae, a special form of
arachnoid membrane, forms the roof of the sella
turcica. The diaphragma tends to be concave or
convex rather than flat, and is rectangular and
somewhat thicker at the periphery5�. All the arterial
Fig. 1 Photograph showing the anatomical relationship
around the sella turcica.
Division of Neurosurgery, St. Marianna University Yokohama City Seibu Hospital
1197�1 Yasashi-cho, Asahi-ku, Yokohama Kanagawa Japan 241�0811
219
1
components of the circle of Willis and the adjacent
carotid artery give origin to multiple perforating
branches, which include the superior hypophyseal
artery and other branches passing to the optic
nerve, chiasm, anterior hypothalamus, and anterior
perforated substance. The posterior communicating
artery courses posteromedially above and medial to
the oculomotor nerve and gives rise to multiple
perforators. The anterior choroidal artery is di-
rected posterolaterally below the optic tract. These
arteries may become stretched over parasellar tu-
mors and may feed them. The dura covering the
anterior clinoid process lateral to the optic nerve
and the carotid artery continues to the interclinoid
ligament and the free edge of the tentorium cerebelli
forming the roof of the dural osteum of cranial
nerve III. This dural osteum is in the roof of the
cavernous sinus. The oculomotor nerve perforates
the dura at this osteum of the oculomotor trigone.
Meckel[s cave containing Gasserian ganglion of thetrigeminal nerve is located underneath the tento-
rium, posteroleteral to the oculomotor trigone. The
medial wall of Meckel[s cave consists of the wall ofthe cavernous sinus. The abducens nerve penetrates
the dura inferomedial to Meckel[s cave. Thetrochlear nerve skirts the free edge of the tentorium
cerebelli and joins the upper part of the cavernous
sinus at the level of its posterolateral angle6�.
Parasellar lesions candidates for a surgical
treatment include cerebral aneurysms, neoplasms,
and rarely congenital lesions. Cerebral aneurysms
are the most common among them. Since the intro-
duction of endovascular coil embolization, the basi-
lar quadrification aneurysms are rarely treated with
a direct surgery. Hence, the anterior circulation
aneurysms are the subjects of this article. Meningio-
mas tend to arise at the tuberculum sellae, the
paraclinoidal region, the lateral wall of cavernous
sinus, the upper clivus, or the cavernous sinus itself.
Radiosurgery appears to take the place of the skull
base surgery in the management of bona fide cav-
ernous sinus meningiomas, because the periopera-
tive morbidity and mortality associated with cav-
ernous sinus surgery is appreciable due to the adja-
cent neurovascular structures7�. Craniopharyngio-
mas commonly grow underneath the optico-
hypothalamic complex to displace it superiorly, and
occasionally in the third ventricle. Neurinomas may
arise fromMeckel[s cave. Dermoids or epidermoidsmay be encountered around the sellar region.
The conventional surgical approaches
to the parasellar region
The conventional surgical approaches to the
parasellar region are as follows: 1� anterior ap-proaches, 2� anterolateral approaches, and 3�lateral approaches �Fig. 2�.
Anterior approaches and their refinement
Major anterior approaches to the parasellar
region are an interhemispheric approach and a sub-
frontal approach.
In an approach through the frontal interhemi-
spheric fissure, dividing the bridging veins associ-
ated with prolonged retraction often causes contu-
sional hemorrhage in the frontal lobe. To avoid this
complication, a craniotomy is made lower than that
of the conventional bifrontal craniotomy because
bridging veins are not found near the frontal base
�Fig. 3�. The lower the approach is, however, themore the chance of damaging the olfactory nerves.
And the opening of the frontal sinus is inevitable.
Fujitsu et al.8� developed the basal interfalcine ap-
proach to overcome the complications described
above. They made two trapezoid craniotomies just
above the supraorbital bar. The basal portion of the
falx cerebri is split into two leaves with a dissector.
There may be multiple tears and holes in the split
falx that can protect the olfactory nerves. When
wider exposure is needed, one or both of two leaves
are cut. The author feels this technique is somewhat
complex, and believes that meticulous dissection
techniques of the arachnoid of the interhemispheric
fissure and around the olfactory nerves following a
simple division of the falx do not give away any
harmful e#ect. In an approach through the frontal
interhemispheric fissure, the lower craniotomy in-
volving the central supraorbital bar is essential to
access aneurysms of the anterior communicating
artery complex or craniopharyngiomas in the third
ventricle without damaging the structures around
the corridor.
The subfrontal approach has been refined to
develop new surgical techniques. The bifrontal
transbasal approach originally developed by Der-
ome and Guiot9� has now become one of the stan-
dard skull base surgical approaches and has been
applied to various kinds of midline skull base le-
sions with some modification10�12�. Kawakami et al.10�
described an extensive transbasal approach consist-
ing of a bilateral frontal craniotomy followed by an
Taguchi Y220
2
en bloc removal of the whole supraorbital bar in
association with the orbital roofs �Fig. 4�. With thisrefinement, retraction forces to the basal frontal
lobe are apparently lessened and reconstruction of
the skull base become to be much easier. The bi-
frontal transbasal approach not only permit a wider
lateral field of vision which is not available with a
transrhinoseptal or transpalatal approach, but also
allows the surgeon to go deeply as far as the infra-
sellar region, the anterior margin of the foramen
magnum, the anterior arch of the atlas and even the
body of C213� �Fig. 5�. Spetzler et al.14� reported atechnique to spare the olfactory function because,
in the bifrontal transbasal approach, the cribriform
plate is usually removed.
No matter what way the surgeon takes, en-
croachment to the frontal sinus is inevitable. There-
fore, great care should be paid to prevent postop-
erative infections. The following method is com-
monly used: the mucosa of the frontal sinus is re-
moved, and the frontonasal ducts are sutured and
covered by fibrin glue. The author uses this method
when the supraorbital bar is totally removed to
access parasellar lesions, and applies the pericranial
flap to obliterate the space of opened frontal sinus.
It seems important not to leave any dead space in
the cranial cavity �cranialization�.Reconstruction of the midline frontal base is
also an important issue requiring a watertight sepa-
ration between the cranial cavity and the upper
respiratory tract, with a support for the brain. Vari-
ous forms of reconstructive procedures have been
reported including skin grafts, full-thickness scalp
grafts, pericranial flaps15�, galeal frontalis myofascial
flaps16�, and free flaps. The author routinely uses the
Fig. 2 The conventional surgical approaches to parasel-
lar region are indicated in a 3D-CT angiogra-
phy: 1� anterior approach, 2� anterolateral ap-proach, and 3� lateral approach. Note that asmall aneurysmal dilatation is seen at the ante-
rior communicating artery complex.
Fig. 3 Operative corridors of the conventional �solidlines� and transbasal �broken lines� approachesare shown. Note that MRI shows a craniopha-
ryngioma in the third ventricle.
Fig. 4 Illustration showing the author[s original cranio-
tomies of an extensive transbasal approach. Two
bone flaps are made: a bifrontal bone flap �F1�and a flap involving the entire supraorbital bar
�F2�.
Surgical approaches to parasellar lesions 221
3
pericaranial flap because this technique is easy to
perform and reliable to prevent infections as well as
CSF rhinorrhea. To reinforce the structural sup-
port, cranial base bone defects anterior to the sella
turcica is reconstructed by using a vascularized
outer table calvarial bone graft17�. The author does
not feel the necessity of bony reconstruction when
the size of a bone defect is less than two thirds of the
anteroposterior length of the anterior cranial fossa.
The bone defect larger than that described above
will be supported by titanium mesh18�.
Anterolateral approaches and their refinement
Until recently, the most common approach to
parasellar lesions has been widely used frontotem-
poral or pterional approach19�. As a matter of fact,
most cerebral aneurysms have been successfully
treated19�. However, this approach has often en-
countered excessive brain retraction and residual
deficits of a disabling nature, when used to access
medially located, large lesions20�. Various types of
craniotomy including the supraorbital bar have
been developed to lessen brain retraction1�.
Al-Mefty21� modified the supraorbital approach re-
fined by Jane et al1�. to enable to access cavernous
sinus lesions by temporal extension of the craniot-
omy. A mobilization of the zygoma in addition to
usual craniotomy has been reported to o#er an
excellent exposure of the cranial base with minimal
retraction22�. Fujitsu and Kuwabara23� reported the
zygomatic approach which involves detachment of
the zygomatic arch of the temporal bone as well as
a portion of the lateral orbital rim as a free bone
flap, and described that their approach permitted
obliquely upward access to the interpeduncular
fossa using the lowest possible supratentorial route.
Similar detachment of the zygomatic arch has been
reported from several institutions24�30�. Hakuba et
al.24, 25� stressed that, in their orbitozygomatic in-
fratemporal approach, manipulation of the vital
structures in the skull base became to be much
easier and safer than that with the conventional
approach because the working distance to the le-
sions in the parasellar region and the interpeduncu-
lar fossa is about 3 cm shorter and the angle to the
lesions about 1 or 2 cm lower than via either the
perional or subtemporal approach. Taguchi et al.31�
have developed a new surgical technique, the fron-
totemporal orbitozygomatico-alar approach, which
combined a supraorbital approach with a detach-
ment of the zygomatic arch. A similar surgical tech-
nique was reported by Zabramski et al.32� three years
later. The author confirmed the advantages de-
scribed above and added two more advantages:
viewing the lesion multidirectionally and accessing
the lesion medial to the optic canal much easier.
However, the author realized that the techniques
described previously needed skillful hands and in-
evitably resected a part of the basal bony structures
of the orbital roof, the sphenoid ridge and the
temporal bone resulting in enophthalmos33� or pul-
sating exophthalmos9�. Recently, Taguchi et al.34�
Fig. 5 a, b Photographs showing preoperative �a� andpostoperative �b� T1-weighted MRI of sagittalview. Note that a large cystic mass �craniopha-ryngioma� in the spheno-nasopharynx is totallyremoved and no cerebral herniation is present.
Taguchi Y222
4
have modified the frontotemporal orbitozygomati-
co-alar approach and developed the frontotemporal
orbito-alar approach to reduce complex and exten-
sive osteotomies on the zygoma. This approach
consists of two bone flaps illustrated in Figure 6
providing a quite similar operative field to the fron-
totemporal orbitozygomatico-alar approach with-
out basal bony defects �Fig. 7�. This approach o#ersa definitive advantage in cranio-orbital approach by
avoiding postoperative complications and by o#e-
ring a simpler, less invasive surgical technique, in
addition to the advantages already provided by the
other cranio-orbital approaches that improve the
angle of the surgeon[s vision and the space availablefor working. Similar modifications to the orbitozy-
gomatic approach were reported more recently35�.
a
b
Fig. 6 a, b Illustrations showing the frontotemporal
orbito-alar approach. Burr holes and osteotomy
incisions are shown on its outer aspect �a� andinner aspect �b�.
a
b
Fig. 7 a, b Intraoperative photographs showing a wide
working space o#ered by the frontotemporal
orbito-alar approach: extradural view of the left
approach �a� and intradural view of the rightapproach �b�.
Surgical approaches to parasellar lesions 223
5
Lateral approaches and their refinement
Modern endovascular surgical techniques ap-
pear to take place the conventional surgical treat-
ment of posterior circulation aneurysms. The sub-
temporal approach had widely been applied to
obliterate basilar bifurcation aneurysms has now
been on the wane. A large parasellar lesions extend-
ing to the middle fossa can be successfully managed
with recently refined anterolateral approaches de-
scribed before �Fig. 8�. Hence, lateral approacheshave become to be used to access around Meckel[scave or the lesions behind the dorsum sellae ��Fig.9�. The subtemporal-transtentorial approach o#ersa surgical field encompassing the upper clivus, but
in which the petrous ridge obscures the surgical
view behind the petrous bone. A common disad-
vantage of this approach has been damage to the
temporal lobe caused by retraction, particularly if
the venous drainage is interrupted20, 36�. In order to
conquer this disadvantage, Kawase et al.37, 38� devel-
oped an anterior transpetrosal-transtentorial ap-
proach. They drilled away the anterior petrous
bone via the epidural route after making a temporal
craniotomy, that is surrounded by the trigeminal
impression anteriorly, the eminentia arcuata poste-
riorly, the major petrosal groove laterally, and the
carotid canal and the internal carotid artery inferi-
orly. Although the superior petrosal sinus is sacri-
ficed inevitably, the sphenopetroclival region down
to the internal auditory meatus can be accessed with
ease. The author, however, recommended a combi-
nation of a subtemporal- transtentorial approach
and an anterior transpetrosal-transtentorial ap-
proach, because the latter provided a fairly limited
working space and access to the petrous apex ex-
tradurally is limited by the subtemporal dura.
Conclusions
Regardless of various techniques described
here, there would be a number of advantages, in-
cluding 1� reducing the brain retraction; 2�shortening the distance to the target; 3� viewingthe lesion directly with a wide working space; and
4� accessing easily to regions used to be no man[sland.
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