Anatomical study of the cavernous sinus emphasizing operative approaches and related vascular and neural reconstruction

The efficacy of three operative approaches to the cavernous sinus (CS) and the possibilities of vascular and cranial nerve reconstruction in and around the CS were studied in 50 cadaver specimens (25 heads). The lateral operative approach was through the lateral wall, between Cranial Nerves V1 and IV, or between Cranial Nerves V1 and V2. The superior approach was through the superior wall of the CS after removing the anterior clinoid process and unroofing the optic canal. The inferior approach followed the petrous internal carotid artery (ICA) into the CS after an extradural subtemporal exposure or after a combined subtemporal and infratemporal fossa exposure. The different exposures of the spaces of the CS and of the intracavernous structures provided by the superior and the lateral approaches were complementary. The exposure provided by the inferior approach was minimal; however, the junction of the petrous and cavernous ICA was best exposed by this route. The combined subtemporal and infratemporal fossa approach exposed the petrous ICA (for proximal control or for reconstruction) with the greatest ease and with the least temporal lobe retraction. The combination of the superior and lateral approaches and the complete mobilization of the intracavernous ICA facilitated its repair after experimental lacerations. Lacerations of either the inferior and the inferomedial aspects of any portion of the cavernous ICA or of the anterior surface of the posterior vertical segment of the artery were the most difficult to repair. End-to-end anastomosis was more difficult with the posterior third of the artery than with the anterior two-thirds. A vein graft with an average length of 3.5 cm could be sutured from the petrous to the supraclinoid ICA to bypass the cavernous ICA, with an average occlusion time of 45 minutes. End-to-end technique was judged better for the proximal anastomosis, but end (graft)-to-side anastomosis was easier to perform at the distal end because of the location of the ophthalmic artery. Resuture of Cranial Nerves III and VI could not be performed in fresh cadavers if the gap exceeded 0.3 cm. In 3 specimens, the exposure of Cranial Nerve VI in the posterior fossa through the petrous apex and in the orbital apex was followed by graft placement (bypassing the CS). The complex anatomy of the cranial nerves at the apex of the CS was also defined in 10 specimens. Surgeons who perform operations in and around the CS for neoplastic and vascular lesions will find these studies useful.     

A combined frontotemporal and lateral infratemporal fossa approach to the skull base

A variety of neoplasms involve both the infratemporal fossa and the base of the middle cranial fossa, in medial proximity to the cavernous sinus and orbital apex. To provide simultaneous access to both the intracranial and extracranial aspects of these tumors, a temporal or frontotemporal craniotomy may be combined with a lateral exposure of the infratemporal fossa. The approach, which is readily achieved by a neurosurgeon and an otolaryngologist acting as a team, involves a unilateral frontotemporal incision extended inferiorly onto the neck, a lateral facial flap reflected anteriorly, and transection of the zygoma followed by its reflection inferolaterally with the temporalis muscle. This exposure provides excellent visualization of both the intradural and extradural aspects of the anterior portion of the cavernous sinus, allowing for an aggressive resection of neoplasms involving this region. Experience with this procedure is reported here in the management of nine patients: three with nasopharyngeal angiofibromas, three with low-grade malignancies of the upper aerodigestive tract, and three with sphenoid ridge meningiomas.     

Exposure of the intracavernous carotid artery in aneurysm surgery

The pterional intradural approach was used in five cases of large and giant carotid-ophthalmic aneurysms and in two cases of intracavernous aneurysms that arose from the anterior siphon knee in the cavernous sinus (CS) and extended into the carotid cistern. In four cases of large carotid-ophthalmic aneurysms removal of the anterior clinoid process and the roof of the optic canal gave easy access to the pericarotid ring. The anteromedial part of the pericarotid ring was dissected to expose the extradural portion of the internal carotid artery (ICA) proximal to the neck and to make enough room between the wall of the CS and the extradural portion of the ICA, thus allowing easy clipping of the neck. In one case of a giant carotid-ophthalmic aneurysm extending into the CS with an extradural origin of the ophthalmic artery and in two cases of an intracavernous aneurysm arising from the siphon knee, neck clipping was performed by opening the lateral wall and roof of the CS after removal of the optic strut. The opening of the lateral wall anterior to the 3rd nerve facilitated wide exposure of the anterior siphon knee. The horizontal portion of the intracavernous ICA as well as the whole aspect of the aneurysm could be exposed as a result of the extended opening of the cavernous roof anterior to the posterior clinoid process. Successful operative results were obtained in all seven patients. A visual field detect as an operative complication was noted in one patient. No disturbance of ocular movements was noted.     

Extradural total petrous apex resection with trigeminal translocation for improved exposure of the posterior cavernous sinus and petroclival region

We have analyzed a strategy for improved exposure of the posterior cavernous sinus and petroclival region through an extradural subtemporal approach to be utilized in the removal of neoplastic processes with involvement of the apical petrous bone and posterior cavernous sinus. This surgical approach includes the following elements for improved exposure of the posterior cavernous sinus through the middle fossa corridor: (1) maximal extradural exposure and mobilization of the trigeminal nerve complex, allowing its elevation and anterior displacement, (2) complete extradural removal of the anterior petrous pyramid from the porus acousticus to the petrous apex under direct vision, (3) total exposure of the abducens nerve from the posterior fossa to its point of cross over the intracavernous carotid artery, and (4) wide extradural exposure of the cavernous carotid artery in the foramen lacerum region. This strategy can be combined with other related approaches; specifically, frontotemporal or posterior transpetrosal exposures for extensive lesions.Microsurgical dissection and morphometric analysis were performed in 20 fixed cadaver specimens for the purposes of validating the method for clinical application and determining the key elements to maximization of exposure. The trigeminal complex could be anteromedially retracted 4.8 mm +/- 1.3 (range = 3 to 6 mm) without skeletonization of V(2) and V(3). Liberating these two divisions from their bony canals to their first peripheral branch (10.4 mm +/- 2.5 and 5.4 mm +/- 1.1, respectively) resulted in increased mobilization an average of 9.1 mm +/- 1.7 (7 to 14 mm). Further mobilization is achieved by dividing the attachment between the trigeminal connective tissue sheath and the fibrous carotid ring at the foramen lacerum. An average of 13.0 mm +/- 3.1 (7 to 20 mm) of the posterior intracavernous carotid artery was exposed. Detailed microanatomic observations and a comprehensive morphometric analysis of the relevant anatomic relationships were made.     

The Petrolingual Ligament: The Anatomy and Surgical Exposure of the Posterolateral Landmark of The Cavernous Sinus

Summary The petrolingual ligament is the posteroinferior attachment of the lateral wall of the cavernous sinus, where the internal carotid artery enters the cavernous sinus. The petrous segment of the internal carotid artery finishes and the cavernous segment begins at the superior margin of this ligament. The ligament is surgically important due to its identification as a landmark for dissection of the internal carotid artery during the approaches to posterolateral intracavernous and extracavernous lesions. It can be well exposed after mobilization of the gasserian ganglion, or after the trigeminal root and ganglion have been split along the junction of V₂ and V₃ (the transtrigeminal approach). The petrolingual ligament was studied in five cadaveric head specimens from ten sides. The size of the ligament was measured, and its anatomical, clinical and surgical importance is discussed.     

Extradural Total Petrous Apex Resection With Trigeminal Translocation for Improved Exposure of the Posterior Cavernous Sinus and Petroclival Region

We have analyzed a strategy for improved exposure of the posterior cavernous sinus and petroclival region through an extradural subtemporal approach to be utilized in the removal of neoplastic processes with involvement of the apical petrous bone and posterior cavernous sinus. This surgical approach includes the following elements for improved exposure of the posterior cavernous sinus through the middle fossa corridor: (1) maximal extradural exposure and mobilization of the trigeminal nerve complex, allowing its elevation and anterior displacement, (2) complete extradural removal of the anterior petrous pyramid from the porus acousticus to the petrous apex under direct vision, (3) total exposure of the abducens nerve from the posterior fossa to its point of cross over the intracavernous carotid artery, and (4) wide extradural exposure of the cavernous carotid artery in the foramen lacerum region. This strategy can be combined with other related approaches; specifically, frontotemporal or posterior transpetrosal exposures for extensive lesions.

Microsurgical dissection and morphometric analysis were performed in 20 fixed cadaver specimens for the purposes of validating the method for clinical application and determining the key elements to maximization of exposure. The trigeminal complex could be anteromedially retracted 4.8 mm ± 1.3 (range = 3 to 6 mm) without skeletonization of V₂ and V₃. Liberating these two divisions from their bony canals to their first peripheral branch (10.4 mm ± 2.5 and 5.4 mm ± 1.1, respectively) resulted in increased mobilization an average of 9.1 mm ± 1.7 (7 to 14 mm). Further mobilization is achieved by dividing the attachment between the trigeminal connective tissue sheath and the fibrous carotid ring at the foramen lacerum. An average of 13.0 mm ± 3.1 (7 to 20 mm) of the posterior intracavernous carotid artery was exposed. Detailed microanatomic observations and a comprehensive morphometric analysis of the relevant anatomic relationships were made.

     

The parasellar osteo-dural chamber and the vascular and neural elements that traverse it. An anatomical concept that would replace the cavernous sinus of classical anatomy

On each side of the sella turcica, because of the existence of vascular and nervous elements, the two aspects of the parasellar segment of the tentorium cerebelli diverge and with the wall of the sphenoid bone form an extradural lodge. In this space are included a venous pathway (the cavernous sinus of the classics), the internal carotid artery and the three oculo-motor cranial nerves. The venous pathway is a plexus of small sized veins, mainly draining the orbital blood, and has neighborhood relations with the carotid. The morphology of the region and the relations of the internal carotid artery and the cranial nerves with the dura propria are the result of the embryonnic development of the brain and the formation of the anterior and middle cerebral fossae. In the parasellar space the cranial nerves have a dural sheath as well as a leptomeningeal one. Nerves III and IV are very close to the lateral wall explaining its multilayered aspect. The internal carotid artery, extradural in its parasellar segment, at the level of the anterior clinoid process, is involved by dura propria to become intradural (the artery does not pierce the dura). Because of the adhesion of the dura propria to the intracranial periosteum the artery is attached to the bone whereas in its extradural and intradural segments it has some mobility. Recent studies have confirmed and completed this topographical concept, first presented in 1949, allowing successful approaches to vascular and tumorous lesions considered inoperable.     

Meningiomas of Meckel's cave.

A series of 16 patients with meningiomas of Meckel's cave is reported. Trigeminal neuralgia, typical or atypical, was the initial symptom in 10 patients (62.5%). At admission, trigeminal signs and symptoms were present in 15 patients (93.7%); in 7 patients (43.7%), trigeminal dysfunction was combined with the impairment of other cranial nerves. On retrospective analysis, these patients fall into two clinical groups that differ also in prognosis. Group 1 comprises eight patients with trigeminal signs and symptoms only. These patients had small meningiomas strictly affecting Meckel's cave. Total removal of the tumor was achieved in seven of eight patients, without adjunctive postoperative neurological deficits. In this group, there were no tumor recurrences. Group 2 comprises the other eight patients in whom trigeminal dysfunction was combined with impairment of other cranial nerves. These patients had large tumors arising from Meckel's cave and secondarily invading the cavernous sinus (five patients) or extending into the posterior fossa (two patients) or largely growing into the middle fossa (one patient). Total removal was achieved in only one patient, and a worsening of the preoperative neurological status was observed in four patients; there were three cases of tumor progression. A subtemporal intradural approach (used in the past in every case) is still used for the small tumors of Group 1 with good results. Since 1985, for tumors involving the cavernous sinus, we have employed a frontotemporal craniotomy with extradural clinoidectomy and superior and lateral approach to the cavernous sinus. When the tumor extends toward the posterior fossa, we use a combined temporosuboccipital-transpetrosal approach.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endoscopic endonasal cavernous sinus surgery: an anatomic study

OBJECTIVE: The endoscopic surgical anatomy of the cavernous sinus was studied to establish an anatomic basis for endoscopic endonasal cavernous sinus surgery. METHODS: Five adult cadaveric heads were studied with 0-, 30-, and 70-degree 4-mm rod-lens endoscopes. The posterior wall of the sphenoidal sinus was approached via a paraseptal, middle turbinectomy, or middle meatal approach. RESULTS: The posterior bony wall of the sphenoidal sinus is subdivided into five vertical compartments: midline, bilateral paramedian, and bilateral lateral. The midline vertical compartment consists of the planum sphenoidale, tuberculum sellae, sella, and clival indentation. The paramedian vertical compartment is composed of the medial third of the optic canal and the carotid artery protuberance. The lateral vertical compartment contains four bony protuberances (optic, cavernous sinus apex, maxillary, and mandibular) and three depressions (carotico-optic, ophthalmomaxillary [V1-V2], and maxillomandibular [V2-V3]). The three depressions form anatomic triangles at the lateral vertical compartment: the optic strut triangle, which is bordered by the optic nerve, carotid artery, and oculomotor nerve (IIIrd cranial nerve); the V1-V2 triangle; and the V2-V3 triangle. The internal carotid artery at the posterior wall of the sphenoidal sinus can be subdivided into two main segments: the parasellar and the paraclival. The vidian canal is a landmark that leads to the foramen lacerum, the mandibular nerve, and the pterygopalatine fossa. CONCLUSION: Endoscopic anatomy of the cavernous sinus has been studied via an endonasal route in cadaveric specimens to provide an anatomic basis for endoscopic endonasal cavernous sinus surgery.     

Frontotemporal orbitozygomatic craniotomy to exposure the cavernous sinus and its surrounding regions. Microsurgical anatomy

BACKGROUND: The microsurgical anatomy of the cavernous sinus and its surrounding regions were examined via frontotemporal orbitozygomatic (FTOZ) craniotomy. Combined with other deep osteotomies, the possibility of exposing the petroclival region and basilar artery was also explored. METHODS: The study was made on 20 sides of 10 cadaveric specimens fixed with formalin, with the help of the surgical microscope (magnification 5-15). RESULTS: The FTOZ was performed with frontotemporal and orbitozygomatic flaps. Extradurally, V2, V3, the trigeminal ganglion, the posterior vertical segment of the intracavernous ICA and the VI nerve were exposed by FTOZ craniotomy. By further removal of the petrous apex (Kawase's triangle), exposure could be extended to the petroclival region; with anterior modification of the microscopic light, in 50% of the specimens, exposure reached as low as the convergence of the vertebral arteries. The anterior part of the cavernous sinus and the orbital apex were examined by removing the anterior clinoid process, orbital roof and unroofing the optic canal. Intradurally, the intrapeduncular fossa (upper 1/3 of the clivus) was examined. The intracavernous cranial nerves and vessels were studied via lateral and superior wall approaches. By removing both the anterior and posterior clinoid processes together, in 80% of the specimens, the exposure could be carried as far as the midpoint of the basilar artery. CONCLUSIONS: FTOZ craniotomy could be used to treat lesions involving the cavernous sinus and its surrounding regions. Incorporated with the petrous apectomy, it could be used to expose the petroclival region and, in selected cases, exposure could be extended to the convergence of the vertebral arteries. Combined with anterior and posterior clinoidectomies, it could also be used to treat midpoint regions of the basilar artery.     

The subtemporal, transcavernous, anterior transpetrosal approach to the upper brain stem and clivus.

The temporal lobe, posterolateral cavernous sinus, tentorium, and petrous apex restrict anterolateral surgical access to lesions of the upper brain stem and clivus. The authors describe a modified transpetrosal approach that enhances the exposure of clival chordomas and aneurysms of the basilar artery bifurcation. An intradural and extradural subtemporal approach is combined with division of the tentorium and superior petrosal sinus, posterolateral dissection of the cavernous sinus, and intradural removal of the petrous bone from its apex to the cochlea. The indications, advantages, and disadvantages of this subtemporal, transcavernous, anterior transpetrosal approach are described in detail, along with its use in six patients.     

An unusual pterygopalatine meningocele associated with neurofibromatosis type 1. Case report

The authors describe an unusual meningocele of the lateral wall of the cavernous sinus and the anterior skull base in a young patient with typical stigmata of neurofibromatosis Type 1 (NF1). This lesion was discovered during evaluation for recurrent meningitis. It represented an anterior continuation of Meckel's cave into a large cerebrospinal fluid space within the lateral wall of the cavernous sinus, extending extracranially through an enlarged superior orbital fissure into the pterygopalatine fossa adjacent to the nasal cavity. It was successfully obliterated, via an intradural middle fossa approach, with fat packing and fenestration into the subarachnoid space. This meningocele most likely represents a variant of cranial nerve dural ectasia occasionally seen in individuals with NF1. It has as its basis the same mesodermal defect responsible for the more common sphenoid wing dysplasia and spinal dural ectasias identified with this condition. Involvement of the trigeminal nerve with expansion of the lateral wall of cavernous sinus has not been reported previously. The authors surmise, however, that it may be present in some cases of orbital meningocele associated with sphenoid wing dysplasia.     

Anterior transpetrosal-transtentorial approach for sphenopetroclival meningiomas: surgical method and results in 10 patients

This report presents a new surgical method and the results in 10 patients with petroclival meningiomas extending into the parasellar region (sphenopetroclival meningiomas). Minimal but effective extradural resection of the anterior petrous bone via a middle fossa craniotomy offered a direct view of the clival area with preservation of the temporal bridging veins and cochlear organs. The dural incision was extended anteriorly to Meckel's cave, and in cases with invasion of the cavernous sinus, Parkinson's triangle was enlarged by mobilization of the trigeminal nerve. This approach offered an excellent view from the mid-clivus to the cavernous sinus. Extra-as well as intradural tumor masses and dural attachments could be cleared under direct view of the pontine surface. The risk of injury to the lower cranial nerve and of retraction damage to the temporal lobe and brain stem were kept minimal by this approach. Total tumor resection was achieved in 7 patients, with no resultant mortality. Eight patients had a satisfactory postsurgical course, extraocular paresis being their main complaint. The extent of tumor resection depended on the degree of tumor adhesion to the carotid artery, and operative morbidity on the degree of tumor invasion of the brain stem. Of the 3 patients in whom subtotal tumor removal was achieved, only one experienced regrowth of the tumor and underwent a second operation during the follow-up period (6 months-6 years).     

Dumbbell-shaped middle cranial fossa meningioma with interdural cavernous sinus extension: report of two cases with complete removal

BACKGROUND: Surgery for meningiomas involving the cavernous sinus remains controversial. Interdural cavernous sinus is called the lateral dural wall in the cavernous sinus, which is composed of two layers, the outer dural layer and the inner membranous layer. We encountered two cases of dumbbell-shaped middle cranial fossa meningioma with interdural cavernous sinus extension, which were successfully removed by surgical means. CASE DESCRIPTION: A 57-year-old woman presented with headache and decreased visual acuity. Neurological assessment was normal. Computed tomography and magnetic resonance imaging showed the presence of a dumbbell-shaped, smooth-contoured, well-enhanced mass in the right mesial temporal area. The lateral wall of the cavernous sinus was exposed via frontotemporal craniotomy and the tumor originating in the lateral wall was totally removed. A 41-year-old man presented with seizure attacks and drowsy mental status. Magnetic resonance imaging showed the presence of a multilobulated, well-enhanced mass in the left parasellar area. The tumor was totally resected via a transsylvian temporopolar approach. The mass originated from tentorial edge and extended into the cavernous sinus by dural penetration. CONCLUSION: Middle cranial fossa meningioma with interdural cavernous sinus extension can be removed more easily than other tumors with intracavernous sinus extension and, consequently, can be safely resected without any resulting cranial nerve deficit.     

Endoscopic endonasal skull base surgery: Part 2--The cavernous sinus.

OBJECTIVE: An endoscopic endonasal approach to the cavernous sinus was developed with cadaver study and, subsequently, has been used in patient treatment. METHODS: The endoscopic anatomy, surgical approaches, and ideal head positioning were studied with six cadaver head specimens in order to develop endoscopic endonasal surgery of the cavernous sinus. Three illustrative patient cases are also reported. RESULTS: Horizontal placement of the forehead-chin line of head specimens provided the ideal head positioning for endoscopic endonasal cavernous sinus surgery. Three different surgical approaches were developed to access the cavernous sinus: the paraseptal, middle meatal and middle turbinectomy approaches. While the ipsilateral middle meatal approach provided straight anterior exposure, the contralateral paraseptal approach provided anteromedial exposure at the cavernous sinus. The middle turbinectomy approach rendered straight anterior exposure ipsilaterally and anteromedial exposure contralaterally. The sympathetic nerve climbed up on the surface of the carotid artery. When the dura mater was opened at the anterior wall of the cavernous sinus, the S-shaped carotid siphon was exposed. Cranial nerves III and IV were located inside the C-shaped carotid siphon. Cranial nerve VI was just lateral to the inferior arch of the carotid siphon. The ophthalmic branch of the trigeminal nerve was lateral to cranial nerve VI. When used in patient treatment, this technique was observed to be minimally invasive. CONCLUSION: Endonasal endoscopy for cavernous sinus surgery was studied in cadaver dissection, and subsequently, was used in patient treatment with satisfactory outcomes.     

Dual-Port 2D and 3D Endoscopy: Expanding the Limits of the Endonasal Approaches to Midline Skull Base Lesions with Lateral Extension

Objective To investigate a novel dual-port endonasal and subtemporal endoscopic approach targeting midline lesions with lateral extension beyond the intracavernous carotid artery anteriorly and the Dorello canal posteriorly. Methods Ten dual-port approaches were performed on five cadaveric heads. All specimens underwent an endoscopic endonasal approach from the sella to middle clivus. The endonasal port was combined with an anterior or posterior endoscopic extradural subtemporal approach. The anterior subtemporal port was placed directly above the middle third of the zygomatic arch, and the posterior port was placed at its posterior root. The extradural space was explored using two-dimensional and three-dimensional endoscopes. Results The anterior subtemporal port complemented the endonasal port with direct access to the Meckel cave, lateral sphenoid sinus, superior orbital fissure, and lateral and posterosuperior compartments of the cavernous sinus; the posterior subtemporal port enhanced access to the petrous apex. Endoscopic dissection and instrument maneuverability were feasible and performed without difficulty in both the anterior and posterior subtemporal ports. Conclusion The anterior and posterior subtemporal ports enhanced exposure and control of the region lateral to the carotid artery and Dorello canal. Dual-port neuroendoscopy is still minimally invasive yet dramatically increases surgical maneuverability while enhancing visualization and control of anatomical structures.     

Dura-based giant intracranial schwannoma in the middle fossa

A 49-year-old female presented with a rare giant schwannoma arising from the dura mater of the middle fossa manifesting as loss of left visual acuity. Magnetic resonance imaging revealed a heterogeneously enhanced giant mass in the left middle fossa. Surgery via the transsylvian approach confirmed the origin of the tumor between the left internal carotid artery and the trigeminal nerve in the lateral wall of the cavernous sinus. Elongated abducens nerve was confirmed, but no tumor adhesion to the abducens nerve was found. The tumor was closely attached to the dura mater of the middle fossa and the lateral wall of the cavernous sinus. The histological diagnosis was schwannoma. Both left oculomotor and abducens nerve pareses occurred immediately after the operation but gradually resolved over 3 months. The operative findings indicated that this schwannoma may have arisen from the meningeal branch of the trigeminal nerve in the dura mater of the middle fossa.     

海绵窦上壁的显微外科解剖学研究

目的 研究海绵窦上壁的显微解剖,为海绵窦直接显微手术的开展提供形态学依据。方法 在手术显微镜下观察和测量了４４侧成人海绵窦上壁结构。 结果 海绵窦上壁呈纵长的四边形。外侧界为前床岩韧带和前床突外缘;内侧界为鞍隔的硬膜缘;前界为前床突基底部和镰状硬膜皱褶;后界为后床岩韧带。上壁的硬膜由浅、两层组成,分别与外侧壁的浅、深层相延续。颈内动脉穿出海绵窦上壁时,浅、深两层硬膜分别形成远侧硬膜环和近侧硬膜环。     

A Lateral Transzygomatic-Transtemporal Approach to the Infratemporal Fossa: Technical Note for Mobilization of the Second and Third Branches of the Trigeminal Nerve

This report describes an alternative approach to the infratemporal fossa lesions through a lateral zygomato-temporal craniotemy, which modifies the extradural temporopolar technique for cavernous sinus surgery. First, an L-shaped osteotomy of the zygoma from the frontozygomatic suture attaching the zygomatre arch and low positioned temporal cramotomy are made. Through this zygomato-temporal craniotomy and orbitotemporal drilling, leaving the lateral orbital rim and orbital roof intact, skeletonization of the foramens rotundum and ovale are carried out. The key element of this infratemporal exposure is the dissection and mobilization of the trigeminal nerve, trigeminal second branch rostrally, and the third branch caudally, which facilitates a wide exposure of the infratemporal fossa with preserving trigeminal function. The corridor between the mobilized trigeminal branches provides direct access to the lateral and medial pterygoid plate, internal maxillary artery, sphenoid and maxillary sinuses, maxilla and, finally, the parapharyngeal area. Our experiences have demonstrated that this lateral transzygomatic-transtemporal exposure is satisfactory for use with infratemporal fossa tumors. This approach has an advantage for cranial-base exposure with decreased risks of cosmetic deformity and of trigeminal nerve dysfunction.     

A lateral transzygomatic-transtemporal approach to the infratemporal fossa: technical note for mobilization of the second and third branches of the trigeminal nerve

This report describes an alternative approach to the infratemporal fossa lesions through a lateral zygomato-temporal craniotemy, which modifies the extradural temporopolar technique for cavernous sinus surgery. First, an L-shaped osteotomy of the zygoma from the frontozygomatic suture attaching the zygomatre arch and low positioned temporal cramotomy are made. Through this zygomato-temporal craniotomy and orbitotemporal drilling, leaving the lateral orbital rim and orbital roof intact, skeletonization of the foramens rotundum and ovale are carried out. The key element of this infratemporal exposure is the dissection and mobilization of the trigeminal nerve, trigeminal second branch rostrally, and the third branch caudally, which facilitates a wide exposure of the infratemporal fossa with preserving trigeminal function. The corridor between the mobilized trigeminal branches provides direct access to the lateral and medial pterygoid plate, internal maxillary artery, sphenoid and maxillary sinuses, maxilla and, finally, the parapharyngeal area. Our experiences have demonstrated that this lateral transzygomatic-transtemporal exposure is satisfactory for use with infratemporal fossa tumors. This approach has an advantage for cranial-base exposure with decreased risks of cosmetic deformity and of trigeminal nerve dysfunction.