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Cranio-orbitozygomatic approach: Technique and modifications
Operative Techniques in Otolaryngology (2013) 24, 229–234
Cranio-orbitozygomatic approach: Technique and modifications Christopher J. Bilbao, DO,a Douglas L. Stofko, DO,a Amir R. Dehdashti, MDb From the aDepartment of Neurosurgery, Philadelphia College of Osteopathic Medicine, Pennsylvania; and the b Department of Neurosurgery, Geisinger Medical Center, Pennsylvania KEYWORDS Orbitozygomatic; Craniotomy; Interfascial; Skull base
The orbitozygomatic craniotomy has been developed and modified over the last three decades, and has become a quintessential approach and technique for the well-rounded neurosurgeon. In this paper, we describe the technique as well as numerous modifications developed in order to suit the various pathologies in the anterior and middle cranial fossae. r 2013 Published by Elsevier Inc.
Introduction
Technique
The orbitozygomatic (OZ) craniotomy has become one of the most versatile neurosurgical approaches owing to its capability in accessing lesions involving the orbital apex, paraclinoid and parasellar areas, basilar apex, cavernous sinus, anterior and middle fossa floor, and brainstem. Since originally described by Jane et al,1 it has undergone multiple revisions involving both technique and indication. It has since evolved to incorporate vascular, skull base, and tumor lesions located anywhere in the anterior and middle fossa. Though its various modifications, it also has been developed as a 1- or 2-piece craniotomy, with the orbital rim reserved as its own osteotomy. There are many advantages of the OZ craniotomy over conventional approaches, such as the pterional and subtemporal. Its greatest allure is decreased brain retraction and increased exposure owing to the increased amount of bony resection. For these reasons, we routinely perform the cranio-OZ approach on most complex lesions described earlier in the article. The purpose of this article is to outline the indications, describe the basic technique, and compare the 1- vs 2-piece modifications.
Under general endotracheal anesthesia, the patient is placed in a supine position and the head is turned 101-601, depending on the pathology, to the contralateral side of the incision and extended slightly so the malar eminence is the most superior point in the surgical field. After a thin strip of hair is clipped, a curvilinear incision is made starting at the inferior border of the zygomatic arch and 5 mm anterior to the tragus. The incision extends anteriosuperiorly behind the hairline to terminate just past the midline (Figure 1A). The temporalis fascia is preserved to conduct an interfascial dissection, as originally described by Yasargil et al.2 The anterior one-fourth of the temporalis muscle is exposed. It is at this level that the anterior portion of the temporalis fascia divides into 2 layers, with a thick fad pad (5-6 mm) interposed (Figure 1B). Contained within this fat pad is the frontal branch of the facial nerve, which must be preserved to prevent paralysis of those muscles supplied by the frontalis nerve. To achieve this interfascial dissection, the superficial layer of the temporalis fascia is incised with a scalpel until the fat pad is encountered. A periosteal dissector is utilized in mobilizing the fat pad anteriorly, thus preserving the frontal branch from further dissection. At this location, there is an interfascial vein that must be coagulated and cut. The deep layer of the superficial temporal fascia is then incised medially at the surface of the frontozygomatic process, extending anteriosuperiorly to the superior orbital rim just lateral to the
Address reprint requests and correspondence: Amir R. Dehdashti, MD, Department of Neurosurgery, Geisinger Medical Center, PA. E-mail address: [email protected] 1043-1810/$ - see front matter r 2013 Published by Elsevier Inc. http://dx.doi.org/10.1016/j.otot.2013.09.004
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Figure 1 (A) The pterional craniotomy incision extending from the root of the zygoma to just past midline. (B) The exposure of the interfascial fat pad. Within this fat pad is the frontotemporal branch of the facial nerve. Sectioning or damage to this nerve leads to paralysis of all muscles supplied by the frontalis nerve. (C) The entire flap exposure, including the orbital rim and zygoma. Enough of the orbital rim needs to be exposed to view and avoid, when appropriate, the supraorbital nerve. (D) Myofascial dissection, including cuff to which the flap will be reattached upon closure. The size of the dissection and subsequent craniotomy is tailored to suit the needs of the lesion. (E) Elevation of temporalis muscle inferiorly. Notice the blood supply and innervation of temporalis has been left intact and we have been allowed the appropriate exposure. (Color version of figure is available online.)
notch of the superior orbital foramen. A subgaleal dissection of the skin flap is sought. In this manner, the galea is separated from the pericranium and the skin flap is reflected anteriorly to expose the orbital rim, malar eminence, and zygomatic root (Figure 1C).
With this exposure complete, the temporalis muscle is incised posteriorly from the fascial plane created to the scalp incision and then inferiorly to the zygoma. A small myofascial cuff is left superiorly for reapproximation upon closure (Figure 1D). Subperiosteal elevation of the temporalis
Bilbao et al.
Cranio-orbitozygomatic Approach
muscle and its deep fascial layer is conducted, reflecting the muscle inferiorly over the zygoma to effectively expose the zygomatic root and pterion, superior orbital rim, zygomatic process, malar eminence, and the zygomatic arch. A blunt dissector is used to expose the orbital rim to its most anterior
231 margin and free the attachment to the periorbita from the lateral and superior aspects of the orbital wall taking care to avoid the supraorbital nerve. It is at this point that we choose to proceed with the 2-piece craniotomy and orbital osteotomy. To achieve this, a
Figure 2 (A) The complete pterional craniotomy. (B) The first osteotomy cut transecting the superior orbital rim and extending into the intracranial compartment. The intraorbital contents are protected with a cottonoid. (C) The second osteotomy cut creating a “V” shape in the frontozygomatic process. (D) The complete zygomatic osteotomy. The root is dissected with cut no. 3, and the frontozygomatic process is excised in 2 cuts. In this instance, the zygoma separated from the frontozygomatic process. (E) The orbitozygomatic osteotomy. Notice the size of the orbital portion, which is considerably larger in the 2-piece osteotomy vs the 1-piece osteotomy. (Color version of figure is available online.)
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Midas-Rex drill is used to place a single burr hole at the posterior aspect of our exposure just inferior to the superior temporal line. A small craniotomy flap is created to suit the need of the lesion being approached, using a combination of the craniotome drill and a 3-mm cutting burr (Figure 2A). Dural tack-up sutures are placed and the sphenoid wing is drilled and bony keels are removed. The muscle is reflected back over the dura, and a reciprocating saw is then used to complete the orbital and zygomatic osteotomies via 6 distinct bone cuts. The first cut is made across the roof of the orbit, just lateral to the supraorbital nerve (Figures 2B and 4). If a more medial exposure is desired, the nerve can be mobilized from its canal, although this is rarely necessary. The saw is placed perpendicular to the orbital roof and a posterior cut is made into the intracranial compartment. Thin retractors protect the dura from the reciprocating saw. The second and third cuts are designed to divide the zygomatic process just above the malar eminence. The second cut starts at the lateroinferior border of the orbital rim and extends obliquely to create a “V”-shaped cut into the frontozygomatic process (Figures 2C and 4). The root of the zygoma is also then cut in an oblique fashion to effectively divide the zygomatic bone.
The fourth cut connects the second cut to the inferior orbital fissure, whereas the fifth cut connects the superior and inferior orbital fissures. Finally, the sixth cut connects the superior orbital fissure to the first cut and release the orbit. Using the 3-mm cutting burr, the superior and inferior orbital fissures are connected once the inferior orbital fissure is identified using either direct visualization or a no. 4 Penfield in the infratemporal fossa. For the sixth cut, the burr is used to connect cuts no. 5 and no. 1 via an inferior orbital route to remove and preserve as much orbital bone as possible. At this point, the periorbital and soft-tissue attachments can be dissected to free the bone flap completely. In the extended modification, the anterior clinoid process is next extradurally removed to expose the optic nerve in the optic canal. The dura propria of the temporal lobe is dissected away from the membranous dura of the cavernous sinus; the anterior clinoid process is isolated and disconnected from the roof of the optic canal and the lesser wing of the sphenoid using the drill. Finally the last attachment to the optic strut is drilled using a small 2- or 3-mm diamond burr and the clinoid is removed en bloc. The clinoid segment of the internal carotid artery and the optic
Figure 3 (A) Reconstruction of the zygoma and lateral orbit using titanium plates and screws. (B) Reapproximation of the orbitozygomatic osteotomies. This portion is attached before the craniotomy. (C) Complete reattachment of craniotomy and orbitozygomatic pieces. The muscle is reapproximated to the myofascial cuff, particularly in the anteriosuperior section to prevent cosmetic defects. (Color version of figure is available online.)
Bilbao et al.
Cranio-orbitozygomatic Approach
nerve are then visualized. The posterior clinoid and upper portions of the clivus can also be drilled with a high-speed diamond burr after intradural exposure, if necessary. For closure, the OZ osteotomy first and frontotemporal bone flaps next are reattached to their anatomical positions with titanium screws and miniplates (Figure 3A-C). The muscle flap and fascia are rotated back into normal position and sutured to the previously created myofascial cuff. Care is taken to close the anterosuperior corner so as to not create a cosmetic defect. The scalp is closed in a multilayer fashion.
Discussion In the late 1980s, Hakuba et al3 described a technique for approaching lesions involving the cavernous sinus, basilar tip, and parasellar regions, which they named the OZ approach. Shortly after, Al-Mefty4 modified a standard pterional approach by combining the superior and lateral orbits into
233 the osteotomy. The contribution of the cranio-OZ approach to the field of neurosurgery is profound through its increased bony exposure and subsequent decreased need for brain retraction. Gonzalez et al5 quantified the working area of the OZ approach to be 343 mm2, as compared with the pterional working area of 281 mm2. They also concluded that the OZ approach had a significantly increased working angle as well, proving the superiority of the OZ approach to its predecessors. Schwartz et al6 quantified increased exposures based on not only the osteotomy performed but also the penultimate target and compared the results to a standard frontotemporal craniotomy. They found that for posterior clinoid targets, exposure was increased by 26% by removing the orbital rim and an additional 13% after removing the zygoma. For basilar tip lesions targets, exposure increased by 28% and 22% by removing the orbital rim and after removing the zygoma, respectively. Clearly, the benefits of wider exposure and less brain retraction counteract the potential increased morbidity to the patient by exposing them to a more extensive procedure.
Figure 4 (A) AP and intraorbital view demonstrating the order of the osteotomy cuts and their orientations. (B) Oblique view demonstrating second and third osteotomy cuts. AP, anteroposterior. (Color version of figure is available online.)
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Operative Techniques in Otolaryngology, Vol 24, No 4, December 2013
There has been discussion in recent literature regarding the difference between the 1- and 2-piece OZ craniotomy. Tanriover et al7 demonstrated the superiority of the 2-piece craniotomy by calculating the total orbitotomy in each, with a clinically and statistically significant advantage for the 2-piece method. The main disadvantage of removing less orbital wall is the smaller exposure of the anterior communicating artery complex and basal frontal lobes. Proponents of the 1-piece craniotomy, however, emphasize a shorter craniotomy time and easier reconstruction compared with the 2-piece. Campero et al8 offer a 3-piece method for the OZ approach, which involves mobilizing the zygomatic bone with the temporalis muscle. This has 2 distinct advantages: there is less soft-tissue retraction overlying the zygomatic bone when making the osteotomy cuts and better access to the inferior lateral wall of the orbit and anterolateral inferior orbital fissure. We do prefer the 2-piece OZ craniotomy because of safer and larger orbital osteotomy and better preservation of orbital roof decreasing the risk of enophthalmus. We have not encountered any specific complication owing to the 2-piece nature of our OZ craniotomies. Complication avoidance is paramount to conduct a successful procedure. Inadvertent exposure of the frontal sinus, improper reconstruction of the orbit leading to enopthalmos or cosmetic deformity, and lesioning of the frontotemporal branch of the facial nerve are the biggest challenges that arise from this approach. Careful dissection and meticulous reconstruction will help avoid such issues.
Conclusion The OZ craniotomy and its various modifications have led to a continued safe approach to various lesions in the anterior and middle fossae. The advantage of the 2-piece over the 1-piece craniotomy is additional bony removal and increased exposure area.
References 1. Jane JA, Park TS, Pobereskin LH, et al: The supraorbital approach: Technical note. Neurosurgery 11:537-542, 1982 2. Yasargil MG, Reichman MV, Kubik S: Preservation of the frontotemporal branch of the facial nerve using the interfascial temporalis flap for pterional craniotomy. J Neurosurg 67:463-466, 1987 3. Hakuba A, Liu S, Nishimura S: The orbitozygomatic infratemporal approach: A new surgical technique. Surg Neurol 26:271-276, 1986 4. Al-Mefty O: Supraorbital-pterional approach to skull base lesions. Neurosurgery 21:474-477, 1987 5. Gonzalez LF, Crawford NR, Horgan MA, et al: Working area and angle of attack in three cranial base approaches: Pterional, orbitozygomatic, and maxillary extension of the orbitozygomatic approach. Neurosurgery 50:550-557, 2002 6. Schwartz MS, Anderson GJ, Horgan MA, et al: Quantification of increased exposure resulting from orbital rim and orbitozygomatic osteotomy via the frontotemporal transylvian approach. J Neurosurg 91:1020-1026, 1999 7. Tanriover N, Ulm AJ, Rhoton AL, et al: One-piece versus two-piece orbitozygomatic craniotomy: Quantitative and qualitative considerations. Neurosurgery 58(ONS 4 suppl 2):ons229-ons237, 2006 8. Campero A, Martins C, Socolovsky M, et al: Three-piece orbitozygomatic approach. Neurosurgery 66(ONS suppl 1):onsE119-onsE120, 2010
Cranio-orbitozygomatic approach: Technique and modifications Christopher J. Bilbao, DO,a Douglas L. Stofko, DO,a Amir R. Dehdashti, MDb From the aDepartment of Neurosurgery, Philadelphia College of Osteopathic Medicine, Pennsylvania; and the b Department of Neurosurgery, Geisinger Medical Center, Pennsylvania KEYWORDS Orbitozygomatic; Craniotomy; Interfascial; Skull base
The orbitozygomatic craniotomy has been developed and modified over the last three decades, and has become a quintessential approach and technique for the well-rounded neurosurgeon. In this paper, we describe the technique as well as numerous modifications developed in order to suit the various pathologies in the anterior and middle cranial fossae. r 2013 Published by Elsevier Inc.
Introduction
Technique
The orbitozygomatic (OZ) craniotomy has become one of the most versatile neurosurgical approaches owing to its capability in accessing lesions involving the orbital apex, paraclinoid and parasellar areas, basilar apex, cavernous sinus, anterior and middle fossa floor, and brainstem. Since originally described by Jane et al,1 it has undergone multiple revisions involving both technique and indication. It has since evolved to incorporate vascular, skull base, and tumor lesions located anywhere in the anterior and middle fossa. Though its various modifications, it also has been developed as a 1- or 2-piece craniotomy, with the orbital rim reserved as its own osteotomy. There are many advantages of the OZ craniotomy over conventional approaches, such as the pterional and subtemporal. Its greatest allure is decreased brain retraction and increased exposure owing to the increased amount of bony resection. For these reasons, we routinely perform the cranio-OZ approach on most complex lesions described earlier in the article. The purpose of this article is to outline the indications, describe the basic technique, and compare the 1- vs 2-piece modifications.
Under general endotracheal anesthesia, the patient is placed in a supine position and the head is turned 101-601, depending on the pathology, to the contralateral side of the incision and extended slightly so the malar eminence is the most superior point in the surgical field. After a thin strip of hair is clipped, a curvilinear incision is made starting at the inferior border of the zygomatic arch and 5 mm anterior to the tragus. The incision extends anteriosuperiorly behind the hairline to terminate just past the midline (Figure 1A). The temporalis fascia is preserved to conduct an interfascial dissection, as originally described by Yasargil et al.2 The anterior one-fourth of the temporalis muscle is exposed. It is at this level that the anterior portion of the temporalis fascia divides into 2 layers, with a thick fad pad (5-6 mm) interposed (Figure 1B). Contained within this fat pad is the frontal branch of the facial nerve, which must be preserved to prevent paralysis of those muscles supplied by the frontalis nerve. To achieve this interfascial dissection, the superficial layer of the temporalis fascia is incised with a scalpel until the fat pad is encountered. A periosteal dissector is utilized in mobilizing the fat pad anteriorly, thus preserving the frontal branch from further dissection. At this location, there is an interfascial vein that must be coagulated and cut. The deep layer of the superficial temporal fascia is then incised medially at the surface of the frontozygomatic process, extending anteriosuperiorly to the superior orbital rim just lateral to the
Address reprint requests and correspondence: Amir R. Dehdashti, MD, Department of Neurosurgery, Geisinger Medical Center, PA. E-mail address: [email protected] 1043-1810/$ - see front matter r 2013 Published by Elsevier Inc. http://dx.doi.org/10.1016/j.otot.2013.09.004
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Operative Techniques in Otolaryngology, Vol 24, No 4, December 2013
Figure 1 (A) The pterional craniotomy incision extending from the root of the zygoma to just past midline. (B) The exposure of the interfascial fat pad. Within this fat pad is the frontotemporal branch of the facial nerve. Sectioning or damage to this nerve leads to paralysis of all muscles supplied by the frontalis nerve. (C) The entire flap exposure, including the orbital rim and zygoma. Enough of the orbital rim needs to be exposed to view and avoid, when appropriate, the supraorbital nerve. (D) Myofascial dissection, including cuff to which the flap will be reattached upon closure. The size of the dissection and subsequent craniotomy is tailored to suit the needs of the lesion. (E) Elevation of temporalis muscle inferiorly. Notice the blood supply and innervation of temporalis has been left intact and we have been allowed the appropriate exposure. (Color version of figure is available online.)
notch of the superior orbital foramen. A subgaleal dissection of the skin flap is sought. In this manner, the galea is separated from the pericranium and the skin flap is reflected anteriorly to expose the orbital rim, malar eminence, and zygomatic root (Figure 1C).
With this exposure complete, the temporalis muscle is incised posteriorly from the fascial plane created to the scalp incision and then inferiorly to the zygoma. A small myofascial cuff is left superiorly for reapproximation upon closure (Figure 1D). Subperiosteal elevation of the temporalis
Bilbao et al.
Cranio-orbitozygomatic Approach
muscle and its deep fascial layer is conducted, reflecting the muscle inferiorly over the zygoma to effectively expose the zygomatic root and pterion, superior orbital rim, zygomatic process, malar eminence, and the zygomatic arch. A blunt dissector is used to expose the orbital rim to its most anterior
231 margin and free the attachment to the periorbita from the lateral and superior aspects of the orbital wall taking care to avoid the supraorbital nerve. It is at this point that we choose to proceed with the 2-piece craniotomy and orbital osteotomy. To achieve this, a
Figure 2 (A) The complete pterional craniotomy. (B) The first osteotomy cut transecting the superior orbital rim and extending into the intracranial compartment. The intraorbital contents are protected with a cottonoid. (C) The second osteotomy cut creating a “V” shape in the frontozygomatic process. (D) The complete zygomatic osteotomy. The root is dissected with cut no. 3, and the frontozygomatic process is excised in 2 cuts. In this instance, the zygoma separated from the frontozygomatic process. (E) The orbitozygomatic osteotomy. Notice the size of the orbital portion, which is considerably larger in the 2-piece osteotomy vs the 1-piece osteotomy. (Color version of figure is available online.)
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Operative Techniques in Otolaryngology, Vol 24, No 4, December 2013
Midas-Rex drill is used to place a single burr hole at the posterior aspect of our exposure just inferior to the superior temporal line. A small craniotomy flap is created to suit the need of the lesion being approached, using a combination of the craniotome drill and a 3-mm cutting burr (Figure 2A). Dural tack-up sutures are placed and the sphenoid wing is drilled and bony keels are removed. The muscle is reflected back over the dura, and a reciprocating saw is then used to complete the orbital and zygomatic osteotomies via 6 distinct bone cuts. The first cut is made across the roof of the orbit, just lateral to the supraorbital nerve (Figures 2B and 4). If a more medial exposure is desired, the nerve can be mobilized from its canal, although this is rarely necessary. The saw is placed perpendicular to the orbital roof and a posterior cut is made into the intracranial compartment. Thin retractors protect the dura from the reciprocating saw. The second and third cuts are designed to divide the zygomatic process just above the malar eminence. The second cut starts at the lateroinferior border of the orbital rim and extends obliquely to create a “V”-shaped cut into the frontozygomatic process (Figures 2C and 4). The root of the zygoma is also then cut in an oblique fashion to effectively divide the zygomatic bone.
The fourth cut connects the second cut to the inferior orbital fissure, whereas the fifth cut connects the superior and inferior orbital fissures. Finally, the sixth cut connects the superior orbital fissure to the first cut and release the orbit. Using the 3-mm cutting burr, the superior and inferior orbital fissures are connected once the inferior orbital fissure is identified using either direct visualization or a no. 4 Penfield in the infratemporal fossa. For the sixth cut, the burr is used to connect cuts no. 5 and no. 1 via an inferior orbital route to remove and preserve as much orbital bone as possible. At this point, the periorbital and soft-tissue attachments can be dissected to free the bone flap completely. In the extended modification, the anterior clinoid process is next extradurally removed to expose the optic nerve in the optic canal. The dura propria of the temporal lobe is dissected away from the membranous dura of the cavernous sinus; the anterior clinoid process is isolated and disconnected from the roof of the optic canal and the lesser wing of the sphenoid using the drill. Finally the last attachment to the optic strut is drilled using a small 2- or 3-mm diamond burr and the clinoid is removed en bloc. The clinoid segment of the internal carotid artery and the optic
Figure 3 (A) Reconstruction of the zygoma and lateral orbit using titanium plates and screws. (B) Reapproximation of the orbitozygomatic osteotomies. This portion is attached before the craniotomy. (C) Complete reattachment of craniotomy and orbitozygomatic pieces. The muscle is reapproximated to the myofascial cuff, particularly in the anteriosuperior section to prevent cosmetic defects. (Color version of figure is available online.)
Bilbao et al.
Cranio-orbitozygomatic Approach
nerve are then visualized. The posterior clinoid and upper portions of the clivus can also be drilled with a high-speed diamond burr after intradural exposure, if necessary. For closure, the OZ osteotomy first and frontotemporal bone flaps next are reattached to their anatomical positions with titanium screws and miniplates (Figure 3A-C). The muscle flap and fascia are rotated back into normal position and sutured to the previously created myofascial cuff. Care is taken to close the anterosuperior corner so as to not create a cosmetic defect. The scalp is closed in a multilayer fashion.
Discussion In the late 1980s, Hakuba et al3 described a technique for approaching lesions involving the cavernous sinus, basilar tip, and parasellar regions, which they named the OZ approach. Shortly after, Al-Mefty4 modified a standard pterional approach by combining the superior and lateral orbits into
233 the osteotomy. The contribution of the cranio-OZ approach to the field of neurosurgery is profound through its increased bony exposure and subsequent decreased need for brain retraction. Gonzalez et al5 quantified the working area of the OZ approach to be 343 mm2, as compared with the pterional working area of 281 mm2. They also concluded that the OZ approach had a significantly increased working angle as well, proving the superiority of the OZ approach to its predecessors. Schwartz et al6 quantified increased exposures based on not only the osteotomy performed but also the penultimate target and compared the results to a standard frontotemporal craniotomy. They found that for posterior clinoid targets, exposure was increased by 26% by removing the orbital rim and an additional 13% after removing the zygoma. For basilar tip lesions targets, exposure increased by 28% and 22% by removing the orbital rim and after removing the zygoma, respectively. Clearly, the benefits of wider exposure and less brain retraction counteract the potential increased morbidity to the patient by exposing them to a more extensive procedure.
Figure 4 (A) AP and intraorbital view demonstrating the order of the osteotomy cuts and their orientations. (B) Oblique view demonstrating second and third osteotomy cuts. AP, anteroposterior. (Color version of figure is available online.)
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Operative Techniques in Otolaryngology, Vol 24, No 4, December 2013
There has been discussion in recent literature regarding the difference between the 1- and 2-piece OZ craniotomy. Tanriover et al7 demonstrated the superiority of the 2-piece craniotomy by calculating the total orbitotomy in each, with a clinically and statistically significant advantage for the 2-piece method. The main disadvantage of removing less orbital wall is the smaller exposure of the anterior communicating artery complex and basal frontal lobes. Proponents of the 1-piece craniotomy, however, emphasize a shorter craniotomy time and easier reconstruction compared with the 2-piece. Campero et al8 offer a 3-piece method for the OZ approach, which involves mobilizing the zygomatic bone with the temporalis muscle. This has 2 distinct advantages: there is less soft-tissue retraction overlying the zygomatic bone when making the osteotomy cuts and better access to the inferior lateral wall of the orbit and anterolateral inferior orbital fissure. We do prefer the 2-piece OZ craniotomy because of safer and larger orbital osteotomy and better preservation of orbital roof decreasing the risk of enophthalmus. We have not encountered any specific complication owing to the 2-piece nature of our OZ craniotomies. Complication avoidance is paramount to conduct a successful procedure. Inadvertent exposure of the frontal sinus, improper reconstruction of the orbit leading to enopthalmos or cosmetic deformity, and lesioning of the frontotemporal branch of the facial nerve are the biggest challenges that arise from this approach. Careful dissection and meticulous reconstruction will help avoid such issues.
Conclusion The OZ craniotomy and its various modifications have led to a continued safe approach to various lesions in the anterior and middle fossae. The advantage of the 2-piece over the 1-piece craniotomy is additional bony removal and increased exposure area.
References 1. Jane JA, Park TS, Pobereskin LH, et al: The supraorbital approach: Technical note. Neurosurgery 11:537-542, 1982 2. Yasargil MG, Reichman MV, Kubik S: Preservation of the frontotemporal branch of the facial nerve using the interfascial temporalis flap for pterional craniotomy. J Neurosurg 67:463-466, 1987 3. Hakuba A, Liu S, Nishimura S: The orbitozygomatic infratemporal approach: A new surgical technique. Surg Neurol 26:271-276, 1986 4. Al-Mefty O: Supraorbital-pterional approach to skull base lesions. Neurosurgery 21:474-477, 1987 5. Gonzalez LF, Crawford NR, Horgan MA, et al: Working area and angle of attack in three cranial base approaches: Pterional, orbitozygomatic, and maxillary extension of the orbitozygomatic approach. Neurosurgery 50:550-557, 2002 6. Schwartz MS, Anderson GJ, Horgan MA, et al: Quantification of increased exposure resulting from orbital rim and orbitozygomatic osteotomy via the frontotemporal transylvian approach. J Neurosurg 91:1020-1026, 1999 7. Tanriover N, Ulm AJ, Rhoton AL, et al: One-piece versus two-piece orbitozygomatic craniotomy: Quantitative and qualitative considerations. Neurosurgery 58(ONS 4 suppl 2):ons229-ons237, 2006 8. Campero A, Martins C, Socolovsky M, et al: Three-piece orbitozygomatic approach. Neurosurgery 66(ONS suppl 1):onsE119-onsE120, 2010