REVIEW Tailoring
the Cranio-orbital
Approach
Ossama Al-Mefty and Robert R. Smith Departmentof NeurosurgeryUniversityof MississippiMedicalCenter,Jackson,MS, USA (Received for publication on July 10, 1990)
Abstract.
The various
described;
the author
modifications uses different
Some of the prime indications December
Key words:
and variations modifications
of the cranio-orbital
according
for these modifications
approach
to the location,
are presented
herein.
have been recently
size and extent
of the lesion.
(Keio J Med 39 (4): 217-224,
1990)
skull base surgery,
suprasellar
tumors,
cerebral
Introduction Both McArthurt in 1912, and Frazier2 in 1913, re moved the supraorbital rim to approach the hypophysis. They thought that this approach offered "greater facilities of access with less trauma to vital structures...".1 Re cently, Jane et al.3 modified and revived this approach, and consider it the approach of choice for orbital tumors. The advantage of including part of the orbital bone with the cranial exposure is so appealing that the author has used a different variation of this technique according to the nature and extent of the lesion at the anterior and middle cranial base.4 Other variations have been de scribed by other authors. 5-10 The following is a descrip tion of some of these variations along with the lesions best approached through them. The Supraorbital Approach The supraorbital approach is best suited for midline s uprasellar masses of small to moderate size, such as tuberculum sellae meningiomas, craniopharyngiomas, intracranial approaches to pituitary tumors, hypothala mic tumors or tumors exposed through the lamina ter minalis, and uni- or bilateral optic nerve decompression as in fibrous.dysplasia and osteopetrosis (Fig. 1). Advantages include a low basal exposure with minimal frontal lobe retraction. There are no functional or cos metic deficits, the operative distance to the sella is short ened and it allows good repair of the floor. Surgical technique The patient is placed supine. A spinal needle is inserted Reprint requests to: Dr. Ossama Al-Mefty, Department 39216-4505, USA
of Neurosurgery
217
aneurysm,
orbital
tumors
througha splitmattress andconnectedto a sterilecollec tion bag. A flowcontrolclamp is applied to the draining tube to avoidrapid lossof cerebrospinalfluid(CSF). The table is adjusted so the trunk and head are elevated 20 degrees. The head is then hyperextendedand fixed in a Mayfield head rest to allow the frontal lobe to fall backward. The head is kept straight to facilitate orientation. After makinga bicoronalincisionbehind the hairline, the scalp flap is turned. The incisionextends from the levelof the zygomaticarch on the operated sideto as far as the superior temporal line on the other side. The superficialtemporal artery and the frontalis branchesof the facialnerve are preservedthroughintrasfacialdissec tion. The temporalismuscleis detachedfrom its insertion anteriorlyto as far as the zygomaticarch; the muscleis then retracted posteriorly,exposingthe junction of the zygomatic,sphenoidal,and frontal bones. The periosteumof the frontal bone is incised pos teriorly, dissected forward, and reflected over the anteriorly turned scalp flap. The intact base of this periosteum is then dissected free from the roof and lateral wallof the orbit. It maybe necessaryto use a high speed air drill around the supraorbitalnotch to free the supraorbitalnerve (Fig. 2, lower inset). To begin the supraorbital approach, two burr holes are drilled. The first, MacCarty'skeyhole,is made in the temporal fossa at the frontosphenoidaljunction, just behind the zygomaticprocessof the frontal bone. When the hole is drilled,the surgeonwillsee that its upper half exposesthe dura mater and its lower half exposes the periorbita, the two membranesbeing separated by the roof of the orbit (Fig.2, upper inset). The secondhole is made in the frontal bone above the nasion. To keep it as University of Mississippi Medical Center 2500 N. State St. Jackson, MS
218
0.
1 Examples of cases suitable for the supraorbital Moderate size tuberculum sellae meningioma,
B C D
Pre-chiasmatic Giant pituitary Hypothalamic
Fig. 2 Artist's illustration demonstrating the supraorbital approach. The midline hole and the keyhole are connected by a cut through the frontal bone using the craniotome, and through the orbital roof using a position of the from its canal.
keyhole.
Lower
al.: Tanunng
Fig. A
small as possible, this hole is made with a high speed drill such as the Midas Rex (Fort Worth, Texas). In adults, this hole will invariably pass through the anterior and posterior walls of the frontal sinus. The mucosa is re moved, and the sinus is packed with a small piece of temporalis muscle. The two holes are joined by two bony cuts. The first
Gigli saw. Upper inset: The Freeing the supraorbital nerve
Al-Meny, et
inset:
me Cramo-oroitai Approach
approach:
craniopharyngioma, tumor, lymphoma.
cut is made by a craniotome, which passes through the frontal bone about 4cm above the superior orbital rim, as shown in Figure 2. The second cut requires the use of a Gigli saw. With a fine bit high speed air drill, a groove is made from the burr hole through the medial part of the superior orbital rim, preserving the trochlea. This groove helps direct the Gigli saw and cut through the orbital roof. A Gigli saw guide is then passed between the two burr holes over the roof of the orbit in the epidural space. The orbital roof is cut as shown in Figure 2. This bony incision is carried laterally and inferiorly, and is continued through the lateral orbital rim. During this process, the contents of the orbit are protected with a brain spatula. The surgeon should pay particular attention to keeping the periorbita intact. Injury to the supra-orbital nerve and the trochlear attach ment of the superior oblique muscle should be avoided. The removed and preserved craniotomy flap thus includes the superior and the upper half of the lateral orbital rim, the anterior portion of the orbital roof, and the adjacent frontal bone. The dura over the lower portion of the frontal pole is opened. A minimal degree of brain retraction is required to reach the sellar area (Fig. 3). At the conclusion of the procedure, the dura is closed watertight. To avoid rhinor rhea, the preserved pericranial flap is turned over the frontal sinus and sutured to the dura mater. A heavy suture is used to reattach the bone flap to the cranial vault. The temporalis muscle is sutured back to the fascia at the lateral orbital rim, and the skin is closed in two layers. The supraorbital approach can be incorporated into a bifrontal flap (Fig. 4) for cases of large and giant tumors extending into the anterior fossa or cases of malignant
Keio J Med 39 (4): 217-224,
219
1990
Fig.3 Enhancedoperativephotograph: Surgeon's viewthroughthe supraorbital approach.The dura(D) is incisedtransversely and re flectedoverthe orbit.Elevationof the frontallobedoesnotexceed 1.5cm.The olfactorytract(I) is dissectedand preserved. The optic nerve(II) and carotidcisternare wellvisualized. R: retractoron the frontallobe.
Fig. 4 Illustration demonstrating the supraorbital bifrontal bone flap. This flap is used for large, benign tumors or malignant tumors that require the inclusion of the orbit with the specimen. Notice the position of the holes
tumors that require including the orbit with craniofacial resection. The Supraorbital-pterional Approach Because it allows excellent exposure of the anterior and middle cranial base with minimal brain retraction, the supraorbital-pterional approach replaces the tra ditional frontotemporal approach in the author's prac tice. Deep lesions can be handled via subfrontal, transsylvian, or subtemporal routes during the same operation. This approach is most suitable for large lesions in the suprasellar, parasellar, and retrosellar areas, and for those extending into the cavernous sinus and/or the orbit, such as clinoidal meningiomas. It is also suitable for primary lesions of the cavernous sinus (tumors, aneurysms, and fistulae), and interpeduncular fossa and
Fig.
5
A B C
Giant aneurysm of the cavernous Anterior clinoid meningioma, Cranio-orbital meningioma.
Examples
of cases
suitable
cuts.
upper clivus tumors (Fig. 5). Little or no functional, anatomical, or cosmetic deficit is evident after the single bone flap is replaced. Surgical technique The patient is placed supine. The head is rotated 30 to 40 degrees to the opposite side, dropped toward the floor, tilted 5 to 10 degrees, and fixed in the Mayfield head rest. The initial skin and fascia exposure is similar to the supraorbital approach described above. Three holes are drilled as shown in Figure 6. The first is made in the frontal bone off the midline above the nasion. For cosmetic reasons, this hole should be kept as small as possible. Entering the frontal sinus is managed as described above. The second hole (the keyhole) is
for the supraorbital-pterional sinus,
and bony
approach:
220
0 . Al-Metty,
et al.: Tarloring
the Cranio-orbital
Approach
similar to the supraorbital-pterional is needed, but through a much smaller flap (Fig. 7). This can be per formed via an eyebrow incision or a conventional curvi linear incision behind the hairline. The patient is placed supine. The head is rotated about 30 degrees to the opposite side, dropped toward the floor, tilted, and fixed in the Mayfield head rest. Three holes are made to remove the bone flap. A high-speed bone drill is used, providing the luxury of a bony incision with minimal defect. A small hole is made in the frontal bone immediately above the superior orbital rim and lateral to the supraorbital nerve, which is left undisturbed. This hole should be kept to minimal size for cosmetic reasons. In the absence of a large frontal sinus, the burr hole remains lateral to the frontal sinus. In the Fig.6 Illustration demonstrating thesupraorbital-pterional approach. presence of a large frontal sinus, however, the sinus may Theboneflapis madebetweenthreeburr holes:the frontal,keyhole, be entered, exenterated and packed with a piece of and temporal.Thebonycutsare outlined. temporalis muscle. The second hole, (the keyhole) is identical to the one described above. The third hole is made posteriorly, near the floor of the temporal fossa. made in the temporal fossa at the frontosphenoidal Between this hole and the keyhole lies the sphenoid junction, just behind the zygomatic process of the frontal ridge which is fractured as the bone flap is removed. bone. The third hole is made posteriorly near the floor of The removed and preserved bone flap thus includes the temporal fossa. the lateral border of the superior orbital rim, the superior The bone between the burr holes is severed as follows. The paramedian frontal burr hole and the posterior temporal burr holes are connected using the craniotome; the blade passes through the frontal and temporal bones about 4cm above the supraorbital rim. The posterior temporal burr holes and the keyhole are likewise connec ted, with the craniotome passing just above the floor of the temporal fossa. The midline and the keyhole are connected by a Gigli saw cut as described above in the supraorbital approach or by incising the lateral orbital rim with the C-1 attachment. The craniotomy flap is then freed by fracturing it at the sphenoid ridge. The removed and preserved bone flap thus includes the superior orbital rim, the upper portion of the lateral orbital rim, the anterior portion of the orbital roof, and the adjacent frontal and temporal bones. The sphenoid wing is then drilled to the base of the anterior clinoid process using a high speed air drill. Should intracavernous sinus surgery be planned, the anterior clinoid can be removed and the optic canal opened extradurally, or these can'be performed after opening the dura. The dura mater is opened with a semicircular incision centered on the pterion, branching from the main incision posteriorly toward the floor of the temporal fossa. This approach provides excellent wide exposure. The Orbitocranial Approach for Aneurysms In cases of aneurysms, particularly ophthalmic and anterior communicating artery aneurysms, an exposure
Fig. 7 Illustration aneurysms.
depicting
the
small
cranio-orbital
flap
used
for
Keio J Med 39 (4): 217-224,
1990
221
part of the lateral orbital rim, the anterior portion of the orbital roof, and a small portion of the adjacent frontal and temporal bone. With a high speed air drill, the sphenoid wing is then drilled to the base of the anterior clinoid process. A semicircular incision centered on the sphenoid ridge is made in the dura. This incision may be extended further from its center toward the floor of the temporal fossa. The sylvian fissure is split in the usual manner. Although a number of carotid-ophthalmic aneurysms have been described, by far the most common is the subchiasmatic type in which the aneurysm projects medially from the surface of the carotid artery along the path of the ophthalmic artery. This aneurysm is best viewed from a medial and superior position. An incision, extending anteriorly toward the frontal fossa, is thus made in the dura covering the anterior clinoid. The dura is separated from the bone exposing the roof of the optic canal to the tuberculum sella. It may be necessary to extend the incision along the base to achieve this exposure. The dural flap is thus turned upward and anteriorly away from the nerve. Using the diamond bit drill, the anterior clinoid is removed and the remaining portions of the lesser sphenoid wing and optic canal are unroofed. Venous bleeding may be encountered here but may be readily controlled using Avetine (Medchem Products, Woburn, MA); Small ethmoidal air cells may also be entered, causing CSF leakage later. In drilling the bony margin, the underlying dura should be preserved since it covers the underlying aneurysm and protects it from the drill. Eventually, the dura propria should be excised and the incision extended along the optic nerve, which is mobilized out of the canal and moved medially, usually off the dome of the aneurysm. This allows visualization of the ophthalmic and carotid arteries as they emerge from the cavernous sinus. In approaching an anterior communicating artery aneurysm, either an interhemispheric or a gyrus rectus approach may be used. Anteriorly and inferiorly project
Fig. 8 A B C
Cases
suitable
for
the superolateral
Venous meningioma in the apex Intracanalicular meningioma, Optic sheath meningioma.
ing aneurysms may be visualized without a gyrus rectus incision. Sliding along the orbital roof anteriorly at the level of the chiasm, medial to the olfactory nerve, the interhemispheric fissure can be opened and its contents visualized adequately. A small ribbon retractor is used to create some pouting of the fissure, opening it for inspec tion. When the aneurysm and its connection to the anterior communicating artery cannot be visualized in this manner, a gyrus rectus incision may be employed. The orbitocranial exposure permits identification and isolation of the A-1 segment at its origin in the internal carotid artery. It also offers much wider and better exposure of an anterior communicating aneurysm. Through a pterional approach, the visualization axis is somewhat lateral. The aneurysm usually projects between the two A-2 segments and may need to be retracted in order to visualize the A-1 and A-2 on both sides. A more anterior projection along the orbital roof, however, often allows visualization of all segments, both A-1's, both A-2's, the communicating artery and the aneurysm. Adhesion between the aneurysm and the opposite A-2, which is difficult to visualize using a pterional approach, is more easily taken care of in the orbitocranial position. The Superolateral Cranio-orbital Approach This modification is used to remove orbital tumors which require a cranial approach and which are not accessible to the lateral and anterior orbital approaches. The superolateral approach gives wide superior and lateral exposure of the orbital contents for microsurgical removal of orbital tumors. It is particularly applicable to large orbital neoplasms, tumors in the orbital apex, optic canal lesions, lesions with intracranial extensions, and medical orbital tumors (Fig. 8). Two separate bone flaps are removed: 1) a craniotomy (or cranio-orbital) flap that includes the superior and lateral orbital rim, and 2) a smaller, more posterior flap that includes the remainder
cranio-orbital
with both
intraorbital
approach: and suprasellar
extensions
,
222
O . Al-Mefty,
et al.: Tailoring
the Cranio-orbital
Approach
of the roof and lateral wall of the orbit. After excision of a tumor, the orbital walls can be reconstructed in their entirety or the surgeon can leave out the smaller posterior flap for orbital decompression. After reconstruction, there are no significant anatomic, functional, or cosmetic deficits. Surgical technique The flap: Patient positioning and skin flap elevation is similar to that of the supraorbital approach described above. The temporalis muscle is detached from its inser tion anteriorly down to as far as the zygomatic arch; the muscle then is retracted posteriorly, exposing the junc tion of the zygomatic, sphenoidal, and frontal bones. The first (cranial or cranio-orbital) bone flap is re moved as follows. Two burr holes are drilled, the frontal hole and the keyhole. These holes are interconnected with a craniotome, which passes through the frontal bone about 4cm above the superior orbital rim as shown in the first step in Figure 9. The second step, also shown in Figure 9, involves using an oscillating blade or prefer ably the B-1 attachment of the Midas Rex drill. This oscillating saw is used to sever the base of the frontal process of the zygomatic bone, with the bony incision extending into the lateral orbital wall formed by the zygomatic bone. The third step in the removal of the cranio-orbital flap requires the use of a Gigli saw to cut through the roof of the orbit as described earlier. The orbit is cut with the Gigli saw as shown in step 3 of Figure 9. This bony incision is carried laterally and inferiorly, close to where the frontal and zygomatic bones meet. The contents of Fig.9 Diagramillustrating the threestagesof removalof thecranial the orbit are protected with a brain spatula during this (cranio-orbital) flap: interconnecting frontaland "keyhole"burrholes, process. The craniotomy flap is then freed by fracturing 1 Craniotome 2 Oscillatingsaw incisingthe baseof the frontalprocessof the it loose at the small, thin lateral orbital wall attachment. zygomatic boneandlateralorbitalwall, In this manner, continuity is maintained between the 3 Giglisawincising theroofoftheorbit.(Reprintedbypermission of lateral orbital rim and the supraorbital portion of the thepublisherfromAl-Mefty0 and FoxJL inSurgicalNeurology flap. The removed and preserved cranio-orbital flap thus 23:601-613,1985,copyright by ElsevierSciencePublishing Co., includes the entire superior and lateral orbital rim, the Inc.) anterior portion of the orbital roof, and the adjacent frontal bone. step 2 of Figure 10. Here the anteroposterior incision The second flap is a smaller posterolateral orbitotomy. extends back through the zygomatic bone and into the The instrument used here is the side-cutting attachment for a high-speed air drill or the C-1 attachment of the greater wing of the sphenoid. These two cuts are inter Midas Rex drill. The orbital contents and the dura mater -connected (Figure 10 right) to permit removal of an over the frontal lobe are gently retracted and protected orbital flap, which includes the posterior portions of the with brain retractors. On the medial part of the roof, an roof and lateral wall of the orbit. Figure 11 illustrates the extensive exposure obtained anteroposterior cut is made through the frontal bone as illustrated in step 1 of Figure 10. The muscle cone by this approach. Bony envelopes have been removed around the optic canal is not interrupted. This cut is without injury to any muscular attachments, nerves, made immediately lateral to the ethmoidal sinuses and vessels, or glands. Thus, combined with microsurgical the trochlear insertion of the superior oblique muscle is techniques, the vast majority of lesions can be exposed left undisturbed. The second bony incision is made in the inside the orbit. If there is any intracranial extension of lower portion-of the lateral wall of the orbit, as shown in an orbital neoplasm, the dura mater can be opened. If
Keio J Med 39 (4): 217-224,
223
1990
larger anterior flap replaced. Otherwise, the entire orbital bone can be reconstructed. The combined flap is repo sitioned to reconstitute the orbital roof and lateral wall. A heavy suture is used to reattach this bone flap to the cranial vault.
Fig. 10 Diagram of removal of the orbital bone flap. Left. Incision along the medial part of the orbital roof (1) and along the inferior portion of the lateral wall of the orbit (2). Right. Connecting the above two cuts to free the orbital flap (broken lines). Note retractors protecting the dura mater of the frontal lobe and periorbita surrounding the orbital contents.
Orbital dissection: Optic nerve gliomas and meningio mas are best approached through the medial orbital space. In the event of an optic nerve glioma, the dura is opened prior to intraorbital sectioning of the tumor. The chiasm is inspected and the optic nerve is then exposed in the orbit. Once the presence of a tumor is confirmed, the optic canal is opened with a high speed air drill and the nerve is sectioned behind the globe and gently ele vated back to the apex. The insertion of the levator muscle is transsected and the annulus of Zinn is opened longitudinally. The nerve is sectioned at the chiasmatic end and removed in total. In the case of an optic nerve meningioma, opening the dura, inspecting the parasellar area, and completely unroofing the optic canal with a high speed drill is necessary. The annulus of Zinn must also be opened as described above (Fig. 12). The meningioma's sheath may then be opened, and the tumor dissected along the course of the optic nerve. Every attempt should be made to preserve the retinal artery, which enters the dura about 10mm behind the globe on the nerve's medial surface. This artery must be protected especially during dissection of the medial portion of the optic nerve. Other authors have recommended removing the optic nerve along with the meningioma, particularly in a young
Fig. 11 Illustration of the skull and orbit after removal of both bone flaps. (Reprinted by permission of the publisher from Al-Mefty 0 and Fox JL in Surgical Neurology 23:601-613, 1985, copyright by Elsevier Science Publishing Co., Inc.) necessary, spinal drainage canal may be unroofed.
can be instituted and the optic Should a permanent decom
pression be required at the end of the procedure, the smaller posterior flap may be discarded and only the
Fig. 12 ningioma
Artist's illustration of optic nerve sheath exposure of: a me via the medial orbital space . The optic canal is unroofed; the levator palpebrae is detached, and the annulus of Zinn is sectioned longitudinally. Part of the tumor is shown medial to the optic nerve in the orbital apex.
224 O
patient, or one suffering severe visual loss. If the annulus of Zinn has been opened , repair should be made by suturing the annulus vertically , a difficult task in children, and reattaching the levator muscle . When the annulus is opened, transient dysfunction of the levator and superior rectus muscles can be expected; recovery ensues in a few weeks to six months. When a mass such as a neurofibroma, neurilemmoma , or hemangioma is located lateral to the optic nerve , the periorbita should be opened lateral to the superior rectus and levator muscles. These muscles are then retracted medially. Using microdissection and fine-tip retractors , a plane of cleavage can be developed around the tumor capsule. Careful dissection of fatty tissue from the tumor capsule is mandatory to preserve extraocular muscle innervation as well as the ciliary branches and ganglion. Dissection within the orbit should be very precise to avoid injury to the retinal blood supply, the autonomic nerves, and branches of the third nerve. An extensive tumor, such as a lymphangioma, may require working through both the lateral and medial spaces. At closure, the outer layer of Tenon's fascia is closed and the periorbita is approximated. The cranial dura is sutured tightly. If the optic canal has been opened and the nerve sectioned, a piece of muscle is left in the canal, and fascia is laid into the optic canal area on the orbital and cranial sides to avoid CSF leakage. The orbital wall is reconstructed as described earlier in this chapter.
. Al-Mefty,
et al.: Tailoring
the Cranio-orbital
Approach
Acknowledgment: The authors are grateful to Ms. Julie Hipp for editori als are assistance and to Ms. Kynda Al-Mefty for her assistance in prepar ing this manuscript. References 1. 2. 3.
4. 5. 6.
McArthur LL: An aseptic surgical access to the pituitary body and its neighborhood. JAMA 58: 2009-2011, 1912 Frazier CH: An approach to the hypophysis through the anterior cranial fossa. Ann Surg 57: 145-152, 1913 Jane JA, Park TS, Pobereskin LH, Winn HR, Butler AB: The supraorbital approach: Technical note. Neurosurgery 11: 537-542, 1982 Al-Mefty 0: Surgery of the Cranial Base. Kluwer AcademicPub lishers, Boston, 1989 Fujitsu K, Kuwabara T: Zygomatic approach for lesions in the interpeduncular cistern. J Neurosurg 62: 340-343, 1985 Hakuba A, Liu S, Nishimura S: The orbitozygomatic infratem
poral approach: A new surgical technique. Surg Neurol 26: 271-276, 1986 7. Mann WJ, Gilsbach J, Seeger W, Fldel H: Use of a malar bone graft to augment skull-base access. Arch Otolaryngol 111: 30-33, 1985 8. Mickey B, Close L, Schaeffer S, Samson D: A combined fronto temporal and lateral infratemporal fossa approach to the skull base. J Neurosurg 68: 678-683, 1988 9. Pellerin P, Lesoin F, Dhellemmes P, Donazzan M, Jomin M: Usefulness of the orbitofrontomalar approach associated with bone reconstruction for frontotemporosphenoid meningiomas. Neurosurgery 15: 715-718, 1984 10. Sekhar LN, Schramm VL Jr, Jones NF: Subtemporal-preauricular infratemporal fossa approach to large lateral and posterior cranial base neoplasms. J Neurosurg 67: 488-499, 1987
the Cranio-orbital
Approach
Ossama Al-Mefty and Robert R. Smith Departmentof NeurosurgeryUniversityof MississippiMedicalCenter,Jackson,MS, USA (Received for publication on July 10, 1990)
Abstract.
The various
described;
the author
modifications uses different
Some of the prime indications December
Key words:
and variations modifications
of the cranio-orbital
according
for these modifications
approach
to the location,
are presented
herein.
have been recently
size and extent
of the lesion.
(Keio J Med 39 (4): 217-224,
1990)
skull base surgery,
suprasellar
tumors,
cerebral
Introduction Both McArthurt in 1912, and Frazier2 in 1913, re moved the supraorbital rim to approach the hypophysis. They thought that this approach offered "greater facilities of access with less trauma to vital structures...".1 Re cently, Jane et al.3 modified and revived this approach, and consider it the approach of choice for orbital tumors. The advantage of including part of the orbital bone with the cranial exposure is so appealing that the author has used a different variation of this technique according to the nature and extent of the lesion at the anterior and middle cranial base.4 Other variations have been de scribed by other authors. 5-10 The following is a descrip tion of some of these variations along with the lesions best approached through them. The Supraorbital Approach The supraorbital approach is best suited for midline s uprasellar masses of small to moderate size, such as tuberculum sellae meningiomas, craniopharyngiomas, intracranial approaches to pituitary tumors, hypothala mic tumors or tumors exposed through the lamina ter minalis, and uni- or bilateral optic nerve decompression as in fibrous.dysplasia and osteopetrosis (Fig. 1). Advantages include a low basal exposure with minimal frontal lobe retraction. There are no functional or cos metic deficits, the operative distance to the sella is short ened and it allows good repair of the floor. Surgical technique The patient is placed supine. A spinal needle is inserted Reprint requests to: Dr. Ossama Al-Mefty, Department 39216-4505, USA
of Neurosurgery
217
aneurysm,
orbital
tumors
througha splitmattress andconnectedto a sterilecollec tion bag. A flowcontrolclamp is applied to the draining tube to avoidrapid lossof cerebrospinalfluid(CSF). The table is adjusted so the trunk and head are elevated 20 degrees. The head is then hyperextendedand fixed in a Mayfield head rest to allow the frontal lobe to fall backward. The head is kept straight to facilitate orientation. After makinga bicoronalincisionbehind the hairline, the scalp flap is turned. The incisionextends from the levelof the zygomaticarch on the operated sideto as far as the superior temporal line on the other side. The superficialtemporal artery and the frontalis branchesof the facialnerve are preservedthroughintrasfacialdissec tion. The temporalismuscleis detachedfrom its insertion anteriorlyto as far as the zygomaticarch; the muscleis then retracted posteriorly,exposingthe junction of the zygomatic,sphenoidal,and frontal bones. The periosteumof the frontal bone is incised pos teriorly, dissected forward, and reflected over the anteriorly turned scalp flap. The intact base of this periosteum is then dissected free from the roof and lateral wallof the orbit. It maybe necessaryto use a high speed air drill around the supraorbitalnotch to free the supraorbitalnerve (Fig. 2, lower inset). To begin the supraorbital approach, two burr holes are drilled. The first, MacCarty'skeyhole,is made in the temporal fossa at the frontosphenoidaljunction, just behind the zygomaticprocessof the frontal bone. When the hole is drilled,the surgeonwillsee that its upper half exposesthe dura mater and its lower half exposes the periorbita, the two membranesbeing separated by the roof of the orbit (Fig.2, upper inset). The secondhole is made in the frontal bone above the nasion. To keep it as University of Mississippi Medical Center 2500 N. State St. Jackson, MS
218
0.
1 Examples of cases suitable for the supraorbital Moderate size tuberculum sellae meningioma,
B C D
Pre-chiasmatic Giant pituitary Hypothalamic
Fig. 2 Artist's illustration demonstrating the supraorbital approach. The midline hole and the keyhole are connected by a cut through the frontal bone using the craniotome, and through the orbital roof using a position of the from its canal.
keyhole.
Lower
al.: Tanunng
Fig. A
small as possible, this hole is made with a high speed drill such as the Midas Rex (Fort Worth, Texas). In adults, this hole will invariably pass through the anterior and posterior walls of the frontal sinus. The mucosa is re moved, and the sinus is packed with a small piece of temporalis muscle. The two holes are joined by two bony cuts. The first
Gigli saw. Upper inset: The Freeing the supraorbital nerve
Al-Meny, et
inset:
me Cramo-oroitai Approach
approach:
craniopharyngioma, tumor, lymphoma.
cut is made by a craniotome, which passes through the frontal bone about 4cm above the superior orbital rim, as shown in Figure 2. The second cut requires the use of a Gigli saw. With a fine bit high speed air drill, a groove is made from the burr hole through the medial part of the superior orbital rim, preserving the trochlea. This groove helps direct the Gigli saw and cut through the orbital roof. A Gigli saw guide is then passed between the two burr holes over the roof of the orbit in the epidural space. The orbital roof is cut as shown in Figure 2. This bony incision is carried laterally and inferiorly, and is continued through the lateral orbital rim. During this process, the contents of the orbit are protected with a brain spatula. The surgeon should pay particular attention to keeping the periorbita intact. Injury to the supra-orbital nerve and the trochlear attach ment of the superior oblique muscle should be avoided. The removed and preserved craniotomy flap thus includes the superior and the upper half of the lateral orbital rim, the anterior portion of the orbital roof, and the adjacent frontal bone. The dura over the lower portion of the frontal pole is opened. A minimal degree of brain retraction is required to reach the sellar area (Fig. 3). At the conclusion of the procedure, the dura is closed watertight. To avoid rhinor rhea, the preserved pericranial flap is turned over the frontal sinus and sutured to the dura mater. A heavy suture is used to reattach the bone flap to the cranial vault. The temporalis muscle is sutured back to the fascia at the lateral orbital rim, and the skin is closed in two layers. The supraorbital approach can be incorporated into a bifrontal flap (Fig. 4) for cases of large and giant tumors extending into the anterior fossa or cases of malignant
Keio J Med 39 (4): 217-224,
219
1990
Fig.3 Enhancedoperativephotograph: Surgeon's viewthroughthe supraorbital approach.The dura(D) is incisedtransversely and re flectedoverthe orbit.Elevationof the frontallobedoesnotexceed 1.5cm.The olfactorytract(I) is dissectedand preserved. The optic nerve(II) and carotidcisternare wellvisualized. R: retractoron the frontallobe.
Fig. 4 Illustration demonstrating the supraorbital bifrontal bone flap. This flap is used for large, benign tumors or malignant tumors that require the inclusion of the orbit with the specimen. Notice the position of the holes
tumors that require including the orbit with craniofacial resection. The Supraorbital-pterional Approach Because it allows excellent exposure of the anterior and middle cranial base with minimal brain retraction, the supraorbital-pterional approach replaces the tra ditional frontotemporal approach in the author's prac tice. Deep lesions can be handled via subfrontal, transsylvian, or subtemporal routes during the same operation. This approach is most suitable for large lesions in the suprasellar, parasellar, and retrosellar areas, and for those extending into the cavernous sinus and/or the orbit, such as clinoidal meningiomas. It is also suitable for primary lesions of the cavernous sinus (tumors, aneurysms, and fistulae), and interpeduncular fossa and
Fig.
5
A B C
Giant aneurysm of the cavernous Anterior clinoid meningioma, Cranio-orbital meningioma.
Examples
of cases
suitable
cuts.
upper clivus tumors (Fig. 5). Little or no functional, anatomical, or cosmetic deficit is evident after the single bone flap is replaced. Surgical technique The patient is placed supine. The head is rotated 30 to 40 degrees to the opposite side, dropped toward the floor, tilted 5 to 10 degrees, and fixed in the Mayfield head rest. The initial skin and fascia exposure is similar to the supraorbital approach described above. Three holes are drilled as shown in Figure 6. The first is made in the frontal bone off the midline above the nasion. For cosmetic reasons, this hole should be kept as small as possible. Entering the frontal sinus is managed as described above. The second hole (the keyhole) is
for the supraorbital-pterional sinus,
and bony
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similar to the supraorbital-pterional is needed, but through a much smaller flap (Fig. 7). This can be per formed via an eyebrow incision or a conventional curvi linear incision behind the hairline. The patient is placed supine. The head is rotated about 30 degrees to the opposite side, dropped toward the floor, tilted, and fixed in the Mayfield head rest. Three holes are made to remove the bone flap. A high-speed bone drill is used, providing the luxury of a bony incision with minimal defect. A small hole is made in the frontal bone immediately above the superior orbital rim and lateral to the supraorbital nerve, which is left undisturbed. This hole should be kept to minimal size for cosmetic reasons. In the absence of a large frontal sinus, the burr hole remains lateral to the frontal sinus. In the Fig.6 Illustration demonstrating thesupraorbital-pterional approach. presence of a large frontal sinus, however, the sinus may Theboneflapis madebetweenthreeburr holes:the frontal,keyhole, be entered, exenterated and packed with a piece of and temporal.Thebonycutsare outlined. temporalis muscle. The second hole, (the keyhole) is identical to the one described above. The third hole is made posteriorly, near the floor of the temporal fossa. made in the temporal fossa at the frontosphenoidal Between this hole and the keyhole lies the sphenoid junction, just behind the zygomatic process of the frontal ridge which is fractured as the bone flap is removed. bone. The third hole is made posteriorly near the floor of The removed and preserved bone flap thus includes the temporal fossa. the lateral border of the superior orbital rim, the superior The bone between the burr holes is severed as follows. The paramedian frontal burr hole and the posterior temporal burr holes are connected using the craniotome; the blade passes through the frontal and temporal bones about 4cm above the supraorbital rim. The posterior temporal burr holes and the keyhole are likewise connec ted, with the craniotome passing just above the floor of the temporal fossa. The midline and the keyhole are connected by a Gigli saw cut as described above in the supraorbital approach or by incising the lateral orbital rim with the C-1 attachment. The craniotomy flap is then freed by fracturing it at the sphenoid ridge. The removed and preserved bone flap thus includes the superior orbital rim, the upper portion of the lateral orbital rim, the anterior portion of the orbital roof, and the adjacent frontal and temporal bones. The sphenoid wing is then drilled to the base of the anterior clinoid process using a high speed air drill. Should intracavernous sinus surgery be planned, the anterior clinoid can be removed and the optic canal opened extradurally, or these can'be performed after opening the dura. The dura mater is opened with a semicircular incision centered on the pterion, branching from the main incision posteriorly toward the floor of the temporal fossa. This approach provides excellent wide exposure. The Orbitocranial Approach for Aneurysms In cases of aneurysms, particularly ophthalmic and anterior communicating artery aneurysms, an exposure
Fig. 7 Illustration aneurysms.
depicting
the
small
cranio-orbital
flap
used
for
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part of the lateral orbital rim, the anterior portion of the orbital roof, and a small portion of the adjacent frontal and temporal bone. With a high speed air drill, the sphenoid wing is then drilled to the base of the anterior clinoid process. A semicircular incision centered on the sphenoid ridge is made in the dura. This incision may be extended further from its center toward the floor of the temporal fossa. The sylvian fissure is split in the usual manner. Although a number of carotid-ophthalmic aneurysms have been described, by far the most common is the subchiasmatic type in which the aneurysm projects medially from the surface of the carotid artery along the path of the ophthalmic artery. This aneurysm is best viewed from a medial and superior position. An incision, extending anteriorly toward the frontal fossa, is thus made in the dura covering the anterior clinoid. The dura is separated from the bone exposing the roof of the optic canal to the tuberculum sella. It may be necessary to extend the incision along the base to achieve this exposure. The dural flap is thus turned upward and anteriorly away from the nerve. Using the diamond bit drill, the anterior clinoid is removed and the remaining portions of the lesser sphenoid wing and optic canal are unroofed. Venous bleeding may be encountered here but may be readily controlled using Avetine (Medchem Products, Woburn, MA); Small ethmoidal air cells may also be entered, causing CSF leakage later. In drilling the bony margin, the underlying dura should be preserved since it covers the underlying aneurysm and protects it from the drill. Eventually, the dura propria should be excised and the incision extended along the optic nerve, which is mobilized out of the canal and moved medially, usually off the dome of the aneurysm. This allows visualization of the ophthalmic and carotid arteries as they emerge from the cavernous sinus. In approaching an anterior communicating artery aneurysm, either an interhemispheric or a gyrus rectus approach may be used. Anteriorly and inferiorly project
Fig. 8 A B C
Cases
suitable
for
the superolateral
Venous meningioma in the apex Intracanalicular meningioma, Optic sheath meningioma.
ing aneurysms may be visualized without a gyrus rectus incision. Sliding along the orbital roof anteriorly at the level of the chiasm, medial to the olfactory nerve, the interhemispheric fissure can be opened and its contents visualized adequately. A small ribbon retractor is used to create some pouting of the fissure, opening it for inspec tion. When the aneurysm and its connection to the anterior communicating artery cannot be visualized in this manner, a gyrus rectus incision may be employed. The orbitocranial exposure permits identification and isolation of the A-1 segment at its origin in the internal carotid artery. It also offers much wider and better exposure of an anterior communicating aneurysm. Through a pterional approach, the visualization axis is somewhat lateral. The aneurysm usually projects between the two A-2 segments and may need to be retracted in order to visualize the A-1 and A-2 on both sides. A more anterior projection along the orbital roof, however, often allows visualization of all segments, both A-1's, both A-2's, the communicating artery and the aneurysm. Adhesion between the aneurysm and the opposite A-2, which is difficult to visualize using a pterional approach, is more easily taken care of in the orbitocranial position. The Superolateral Cranio-orbital Approach This modification is used to remove orbital tumors which require a cranial approach and which are not accessible to the lateral and anterior orbital approaches. The superolateral approach gives wide superior and lateral exposure of the orbital contents for microsurgical removal of orbital tumors. It is particularly applicable to large orbital neoplasms, tumors in the orbital apex, optic canal lesions, lesions with intracranial extensions, and medical orbital tumors (Fig. 8). Two separate bone flaps are removed: 1) a craniotomy (or cranio-orbital) flap that includes the superior and lateral orbital rim, and 2) a smaller, more posterior flap that includes the remainder
cranio-orbital
with both
intraorbital
approach: and suprasellar
extensions
,
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Approach
of the roof and lateral wall of the orbit. After excision of a tumor, the orbital walls can be reconstructed in their entirety or the surgeon can leave out the smaller posterior flap for orbital decompression. After reconstruction, there are no significant anatomic, functional, or cosmetic deficits. Surgical technique The flap: Patient positioning and skin flap elevation is similar to that of the supraorbital approach described above. The temporalis muscle is detached from its inser tion anteriorly down to as far as the zygomatic arch; the muscle then is retracted posteriorly, exposing the junc tion of the zygomatic, sphenoidal, and frontal bones. The first (cranial or cranio-orbital) bone flap is re moved as follows. Two burr holes are drilled, the frontal hole and the keyhole. These holes are interconnected with a craniotome, which passes through the frontal bone about 4cm above the superior orbital rim as shown in the first step in Figure 9. The second step, also shown in Figure 9, involves using an oscillating blade or prefer ably the B-1 attachment of the Midas Rex drill. This oscillating saw is used to sever the base of the frontal process of the zygomatic bone, with the bony incision extending into the lateral orbital wall formed by the zygomatic bone. The third step in the removal of the cranio-orbital flap requires the use of a Gigli saw to cut through the roof of the orbit as described earlier. The orbit is cut with the Gigli saw as shown in step 3 of Figure 9. This bony incision is carried laterally and inferiorly, close to where the frontal and zygomatic bones meet. The contents of Fig.9 Diagramillustrating the threestagesof removalof thecranial the orbit are protected with a brain spatula during this (cranio-orbital) flap: interconnecting frontaland "keyhole"burrholes, process. The craniotomy flap is then freed by fracturing 1 Craniotome 2 Oscillatingsaw incisingthe baseof the frontalprocessof the it loose at the small, thin lateral orbital wall attachment. zygomatic boneandlateralorbitalwall, In this manner, continuity is maintained between the 3 Giglisawincising theroofoftheorbit.(Reprintedbypermission of lateral orbital rim and the supraorbital portion of the thepublisherfromAl-Mefty0 and FoxJL inSurgicalNeurology flap. The removed and preserved cranio-orbital flap thus 23:601-613,1985,copyright by ElsevierSciencePublishing Co., includes the entire superior and lateral orbital rim, the Inc.) anterior portion of the orbital roof, and the adjacent frontal bone. step 2 of Figure 10. Here the anteroposterior incision The second flap is a smaller posterolateral orbitotomy. extends back through the zygomatic bone and into the The instrument used here is the side-cutting attachment for a high-speed air drill or the C-1 attachment of the greater wing of the sphenoid. These two cuts are inter Midas Rex drill. The orbital contents and the dura mater -connected (Figure 10 right) to permit removal of an over the frontal lobe are gently retracted and protected orbital flap, which includes the posterior portions of the with brain retractors. On the medial part of the roof, an roof and lateral wall of the orbit. Figure 11 illustrates the extensive exposure obtained anteroposterior cut is made through the frontal bone as illustrated in step 1 of Figure 10. The muscle cone by this approach. Bony envelopes have been removed around the optic canal is not interrupted. This cut is without injury to any muscular attachments, nerves, made immediately lateral to the ethmoidal sinuses and vessels, or glands. Thus, combined with microsurgical the trochlear insertion of the superior oblique muscle is techniques, the vast majority of lesions can be exposed left undisturbed. The second bony incision is made in the inside the orbit. If there is any intracranial extension of lower portion-of the lateral wall of the orbit, as shown in an orbital neoplasm, the dura mater can be opened. If
Keio J Med 39 (4): 217-224,
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1990
larger anterior flap replaced. Otherwise, the entire orbital bone can be reconstructed. The combined flap is repo sitioned to reconstitute the orbital roof and lateral wall. A heavy suture is used to reattach this bone flap to the cranial vault.
Fig. 10 Diagram of removal of the orbital bone flap. Left. Incision along the medial part of the orbital roof (1) and along the inferior portion of the lateral wall of the orbit (2). Right. Connecting the above two cuts to free the orbital flap (broken lines). Note retractors protecting the dura mater of the frontal lobe and periorbita surrounding the orbital contents.
Orbital dissection: Optic nerve gliomas and meningio mas are best approached through the medial orbital space. In the event of an optic nerve glioma, the dura is opened prior to intraorbital sectioning of the tumor. The chiasm is inspected and the optic nerve is then exposed in the orbit. Once the presence of a tumor is confirmed, the optic canal is opened with a high speed air drill and the nerve is sectioned behind the globe and gently ele vated back to the apex. The insertion of the levator muscle is transsected and the annulus of Zinn is opened longitudinally. The nerve is sectioned at the chiasmatic end and removed in total. In the case of an optic nerve meningioma, opening the dura, inspecting the parasellar area, and completely unroofing the optic canal with a high speed drill is necessary. The annulus of Zinn must also be opened as described above (Fig. 12). The meningioma's sheath may then be opened, and the tumor dissected along the course of the optic nerve. Every attempt should be made to preserve the retinal artery, which enters the dura about 10mm behind the globe on the nerve's medial surface. This artery must be protected especially during dissection of the medial portion of the optic nerve. Other authors have recommended removing the optic nerve along with the meningioma, particularly in a young
Fig. 11 Illustration of the skull and orbit after removal of both bone flaps. (Reprinted by permission of the publisher from Al-Mefty 0 and Fox JL in Surgical Neurology 23:601-613, 1985, copyright by Elsevier Science Publishing Co., Inc.) necessary, spinal drainage canal may be unroofed.
can be instituted and the optic Should a permanent decom
pression be required at the end of the procedure, the smaller posterior flap may be discarded and only the
Fig. 12 ningioma
Artist's illustration of optic nerve sheath exposure of: a me via the medial orbital space . The optic canal is unroofed; the levator palpebrae is detached, and the annulus of Zinn is sectioned longitudinally. Part of the tumor is shown medial to the optic nerve in the orbital apex.
224 O
patient, or one suffering severe visual loss. If the annulus of Zinn has been opened , repair should be made by suturing the annulus vertically , a difficult task in children, and reattaching the levator muscle . When the annulus is opened, transient dysfunction of the levator and superior rectus muscles can be expected; recovery ensues in a few weeks to six months. When a mass such as a neurofibroma, neurilemmoma , or hemangioma is located lateral to the optic nerve , the periorbita should be opened lateral to the superior rectus and levator muscles. These muscles are then retracted medially. Using microdissection and fine-tip retractors , a plane of cleavage can be developed around the tumor capsule. Careful dissection of fatty tissue from the tumor capsule is mandatory to preserve extraocular muscle innervation as well as the ciliary branches and ganglion. Dissection within the orbit should be very precise to avoid injury to the retinal blood supply, the autonomic nerves, and branches of the third nerve. An extensive tumor, such as a lymphangioma, may require working through both the lateral and medial spaces. At closure, the outer layer of Tenon's fascia is closed and the periorbita is approximated. The cranial dura is sutured tightly. If the optic canal has been opened and the nerve sectioned, a piece of muscle is left in the canal, and fascia is laid into the optic canal area on the orbital and cranial sides to avoid CSF leakage. The orbital wall is reconstructed as described earlier in this chapter.
. Al-Mefty,
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Acknowledgment: The authors are grateful to Ms. Julie Hipp for editori als are assistance and to Ms. Kynda Al-Mefty for her assistance in prepar ing this manuscript. References 1. 2. 3.
4. 5. 6.
McArthur LL: An aseptic surgical access to the pituitary body and its neighborhood. JAMA 58: 2009-2011, 1912 Frazier CH: An approach to the hypophysis through the anterior cranial fossa. Ann Surg 57: 145-152, 1913 Jane JA, Park TS, Pobereskin LH, Winn HR, Butler AB: The supraorbital approach: Technical note. Neurosurgery 11: 537-542, 1982 Al-Mefty 0: Surgery of the Cranial Base. Kluwer AcademicPub lishers, Boston, 1989 Fujitsu K, Kuwabara T: Zygomatic approach for lesions in the interpeduncular cistern. J Neurosurg 62: 340-343, 1985 Hakuba A, Liu S, Nishimura S: The orbitozygomatic infratem
poral approach: A new surgical technique. Surg Neurol 26: 271-276, 1986 7. Mann WJ, Gilsbach J, Seeger W, Fldel H: Use of a malar bone graft to augment skull-base access. Arch Otolaryngol 111: 30-33, 1985 8. Mickey B, Close L, Schaeffer S, Samson D: A combined fronto temporal and lateral infratemporal fossa approach to the skull base. J Neurosurg 68: 678-683, 1988 9. Pellerin P, Lesoin F, Dhellemmes P, Donazzan M, Jomin M: Usefulness of the orbitofrontomalar approach associated with bone reconstruction for frontotemporosphenoid meningiomas. Neurosurgery 15: 715-718, 1984 10. Sekhar LN, Schramm VL Jr, Jones NF: Subtemporal-preauricular infratemporal fossa approach to large lateral and posterior cranial base neoplasms. J Neurosurg 67: 488-499, 1987
