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.     

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.     

Transpterygoid Trans-sphenoid Approach to the Lateral Extension of the Sphenoid Sinus to Repair a Spontaneous CSF Leak.

Objective and Importance: Cerebrospinal fluid (CSF) fistula from the middle cranial fossa into the sphenoid sinus is a rare condition. In the past, the treatment of choice has been closure via a craniotomy. Only few geriatric cases are known, which were successfully operated by endoscopic surgery. We present a further case of nontraumatic CSF fistula originating from the middle cranial fossa. A new endoscopic technique was applied. We discuss treatment options for this rare defect. Clinical Presentation: A 76-year-old patient presented with a 2-year history of rhinorrhea. High levels of beta-trace protein pointed to a diagnosis of CSF fistula. The defect was located at the anterior and inferior aspect of the pterygoid recess of the left sphenoid sinus. Intervention: The patient was operated using an endoscopic trans-sphenoidal approach. After endoscopic opening of the maxillary and sphenoid sinus, a complete posterior ethmoidectomy was performed. The medial part of the pterygoid process was removed, allowing endoscopic exposure and closure of the defect. At 1-year follow-up, the CSF fistula had not recurred and the patient had no sequel from the surgical procedure. Conclusion: In selected cases, this new endoscopic partial transpterygoid approach to the middle cranial fossa is recommended for surgical repair of CSF fistula involving the lateral extension of the sphenoid sinus. To our knowledge, ours is the oldest patient with this condition successfully operated by endoscopic means at the world's most northern university hospital.     

The endoscopic supraorbital approach to tumors of the middle cranial base

BACKGROUND: Access to tumors of the middle cranial base has traditionally required wide surgical exposures via open craniotomies. These open techniques often require the use of potentially disfiguring skin incisions and are often associated with a significant degree of brain retraction and potential morbidity. We report our experience with the use of a minimally invasive supraorbital endoscopic approach through the eyebrow for excision of middle cranial base tumors in 2 cases. METHODS: We describe 2 patients with large-sized middle cranial fossa tumors (a medial sphenoid wing meningioma measuring 6 x 4 cm and a recurrent right cavernous sinus meningioma measuring 4 x 3.5 cm) that were entirely removed via a fully endoscopic supraorbital approach using a 1.5-cm keyhole craniotomy. CONCLUSION: These cases demonstrate how the application of endoscopic techniques to surgery of the middle cranial base can eliminate the need for traditional open techniques without compromising surgical success.     

Endoscopic endonasal approaches to the cavernous sinus: surgical approaches

OBJECTIVE: After completion of an earlier endoscopic transsphenoidal anatomic study, we studied various endoscopic transsphenoidal approaches using cadaveric specimens to develop endoscopic endonasal surgical approaches to the cavernous sinus. METHODS: Ten cavernous sinuses in five artery-injected adult cadaveric heads were studied with 0-, 30-, and 70-degree angled 4-mm rod-lens endoscopes. The extent of the surgical exposure, the skewed endoscopic anatomic view, and the maneuverability of surgical instruments through their relative operating spaces were studied after various endoscopic endonasal approaches via one nostril. RESULTS: The paraseptal approach was used between the nasal septum and the middle turbinate and provided exposure at the anteromedial portion of the cavernous sinus. The contralateral paraseptal approach rendered a slightly more medial view at the cavernous sinus than did the ipsilateral approach. This approach offered limited surgical access to the lateral vertical compartment. The middle turbinectomy approach allowed surgical access to the lateral wall of the cavernous sinus, except for the superior orbital fissure and the orbital apex. The middle meatal approach, which was made between the middle turbinate and the lateral nasal wall, revealed the entire lateral vertical compartment of the cavernous sinus, including the orbital apex and the superior orbital fissure. However, its lateral tangential surgical trajectory and the absence of dedicated surgical tools limited the surgeon's surgical maneuverability. A combination of the middle turbinectomy and middle meatal approaches increased the operating space. CONCLUSION: Various endoscopic endonasal surgical approaches to the cavernous sinus were studied using adult cadaveric head specimens.     

Endoscopic neuroanatomy through the sphenoid sinus.

OBJECT: The aim of the study was to perform endoscopic anatomical studies of skull base structures through the sphenoid sinus in order to better understand endoscopic approaches to skull base lesions. METHODS: Anatomical studies were performed on six cadavers using sinus endoscopes. The sphenoid sinus was entered via a sublabial nasoseptal approach. Stepwise removal of bone surrounding the sphenoid sinus was done to expose the suprasellar area, the retrosphenoid area and the cavernous sinus. The suprasellar dissection exposed the anterior communicating artery (ACom) complex, optic apparatus, pituitary stalk, lamina terminalis, third ventricle and pituitary gland. The retrosphenoid dissection exposed the mamillary bodies, basilar artery and its branches, the mid-brain, the pons, and the third, fifth, sixth, seventh and eighth cranial nerves. The cavernous sinus dissection exposed the carotid artery, and the third, fourth, fifth and the sixth cranial nerves. CONCLUSION: Through the sphenoid sinus, most of the structures in the suprasellar area, cavernous sinus and retrosphenoid area can be reached.     

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.     

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.     

Endoscopic Orientation of the Parasellar Region in Sphenoid Sinus with Ill-Defined Bony Landmarks: An Anatomic Study

The sphenoid bony landmarks are important for endoscopic orientation in skull base surgery but show a wide range of variations. We aimed to describe an instructional model for the endoscopic parasellar anatomy in sphenoid sinuses with ill-defined bony landmarks. Five preserved injected cadaveric heads and four sides of dry skulls were studied endoscopically via transethmoid, transsphenoidal approach. The parasellar region was exposed by drilling along the maxillary nerve (V2) canal [the length of the foramen rotundum (FR) between the middle cranial fossa and the pterygopalatine fossa]. This was achieved by drilling in the inferior part of the lateral wall of posterior ethmoids immediately above the sphenopalatine foramen. Cavernous V2 was traced to the paraclival internal carotid artery (ICA). Cavernous sinus (CS) apex was exposed by drilling a triangle bounded by V2 and its canal inferiorly, bone between FR and superior orbital fissure (SOF) anteriorly, and ophthalmic nerve (V1) superiorly. Drilling was continued toward the annulus of Zinn (AZ) and optic nerve superiorly and over the intracavernous ICA posteriorly. Endoscopic measurements between V2, SOF, AZ, and opticocarotid recess were obtained. Endoscopic systematic orientation of parasellar anatomy is presented that can be helpful for approaching sphenoid sinus with ill-defined bony landmarks.     

Endoscopic endonasal repair of a temporal lobe meningoencephalocele in the pterygoid fossa: A case report and literature review

IntroductionMeningoceles are defined as herniation of the meninges through a skull base defect. If brain tissue is herniated as well, then it is called meningoencephalocele. The most common locations of meningoceles are the cribriform plate and the lateral recess of the sphenoid sinus, with the most common presentation being CSF leakage. We present a case of temporal lobe meningocele that herniated through a defect in the greater wing of the sphenoid bone to the pterygoid fossa and that was diagnosed incidentally while evaluating the patient for seizures.MethodologyCase report and literature review.ConclusionThe endonasal endoscopic approach is a suitable minimally invasive approach for the management of pterygoid fossa lesions, including meningoceles. In this case, the patient had epilepsy with the surgery resulting in the resolution of the seizures.     

Recurrent angiofibroma invading the skull base--case report

A 16-year-old male presented with a massive nasopharyngeal angiofibroma arising in the nasopharynx, nasal cavity, pterygopalatine fossa, and infratemporal fossa, and eroding the pterygoid process of the sphenoid bone. Neuroimaging showed the tumor had infiltrated the parasellar region from the middle cranial fossa and reached the cavernous sinus. The tumor was almost completely removed macroscopically by a modified transbasal approach.     

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.     

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.     

Facial translocation: a new approach to the cranial base

Nasopharynx, clivus, and cavernous sinus are difficult regions of the cranial base in which to perform oncologic surgery. We have developed an approach to this area by using facial soft tissue translocation and craniofacial osteotomies. Surgical field obtained at the skull base can extend from the contralateral eustachian tube to ipsilateral geniculate ganglion. It includes the nasopharynx, clivus, sphenoid, and cavernous sinus, as well as the entire infratemporal fossa and superior orbital fissure. Our experience with this technique in 12 patients is reported. All patients healed primarily.     

Microsurgical Anatomy of the Cavernous Sinus: Measurements of the Triangles in and around It.

Objectives: Since the pioneering work of Parkinson, several studies have described the microsurgical anatomy and surgical procedures involving the cavernous sinus (CS). A proposed geometric construct has been adopted as nomenclature for the region by many neurosurgeons. However, authors differ in naming and describing some of these triangular spaces. The purpose of this study is to present the anatomy and measure the dimensions of the 10 triangles in and around this region. Materials and Methods: Eighteen CS of five cadaveric heads and four skull bases fixed in formalin were dissected using 3 x to 40 x magnification of the surgical microscope. The heads and skull bases were injected with colored silicone and the sides and area of the triangles were measured. Each cadaveric head was placed in a Sugita head-holder and a cranio-orbitozygomatic approach and a combined extra- and intradural approach were performed. The last step was the detachment of the brain from the skull base and measurement of the inferolateral paraclival and inferomedial paraclival triangles. Results: The measurements of the medial border, lateral border, and base of each triangle as well as the standard deviation and area are presented. The posteromedial middle fossa triangle was the largest and the clinoidal triangle the smallest. Conclusions: The normal anatomy of the CS triangle and its areas are important in the approach of the CS lesions because these spaces are natural corridors through which the lesions can be reached. The same concept must be used for the triangles around this space. Whenever these geometric spaces might be distorted by pathology or surgical maneuvers, the surgeon must have precise knowledge about their normal sizes.     

Transnasal Endoscopic Resection of a Cavernous Sinus Hemangioma: Technical Note and Review of the Literature

Objective/Importance: Hemangiomas of the cavernous sinus are rare lesions. Complete removal through a transcranial route often causes ocular motor palsies. Because the cranial nerves in the cavernous sinus are lateral to the carotid, a medial approach to the cavernous sinus may be less traumatic to the cranial nerves. Clinical Presentation: A 50-year-old man with headaches, dizziness, diplopia, and magnetic resonance imaging that demonstrated a right cavernous sinus mass expanding into the sella and sphenoid sinus. Intervention: A gross total removal of a cavernous sinus hemangioma was performed through an extended endoscopic transsphenoidal approach. Conclusion: This is the first report of a complete removal of a cavernous sinus hemangioma using an endoscopic transnasal approach. The endoscopic transnasal approach to the medial cavernous sinus may be less traumatic than the transcranial route based on the lateral location of the cranial nerves.     

Endoscopic Endonasal Repair of Cerebrospinal Fluid Leakage Caused by a Rare Traumatic Clival Fracture

An 89-year-old male presented with cerebrospinal fluid (CSF) rhinorrhea associated with head trauma sustained as a pedestrian in a traffic accident. Computed tomography (CT) showed pneumocephalus and multiple cranial bone fractures, including the clivus. Although the CSF rhinorrhea was treated conservatively for a week, clinical symptoms did not improve and surgical repair was performed. Preoperative thin-sliced bone CT and steady-state magnetic resonance images revealed a bone defect at the middle clivus and a collection of CSF fluid from the clival fistula in the sphenoid sinus. Endoscopic endonasal reconstruction was performed, and the 3-mm diameter dural tear and bone defect at the middle clivus were well visualized. The fistula was repaired using a pedicled nasoseptal mucosal flap. The CSF rhinorrhea completely disappeared as a result of the endoscopic endonasal surgery. The present report describes a rare case of CSF rhinorrhea caused by a traumatic clival fracture and surgical management by endoscopic endonasal surgery.     

Endoscopic endonasal approach to the pterygopalatine fossa: anatomic study

OBJECTIVE: The pterygopalatine fossa is a relatively small anatomic region. Because of its rich vasculonervous contents and its connections with several intracranial and extracranial compartments, it is of particular surgical interest. Because of its deep localization and despite its small size, however, it can require extensive anatomic approaches, especially for invasive cranial base lesions. We performed a cadaveric study through a minimally invasive endoscopic endonasal approach to the pterygopalatine fossa. METHODS: We studied 16 pterygopalatine fossae in eight adult cadaveric heads in which the arteries and veins were injected with latex. For visualization, we used rod-lens endoscopes, 4 mm in diameter and 18 cm in length, with 0-, 30-, 45-, and 70-degree lenses. An endonasal middle meatal transpalatine approach, an endonasal middle meatal transantral approach, and an endonasal inferior turbinectomy transantral approach were used. RESULTS: The middle meatal transpalatine approach allows for medial exposure of the pterygopalatine fossa contents, the middle meatal transantral approach allows a lateral view, and the inferior turbinectomy transantral approach allows the widest view and room for surgical maneuvering in the medial and lateral compartments of the pterygopalatine fossa and the infratemporal fossa. CONCLUSION: Our anatomic study shows that this approach can be considered a valid minimally invasive option to approach pterygopalatine fossa lesions.     

Extended endoscopic endonasal transclival approach to the ventrolateral brainstem and related cisternal spaces: anatomical study

Advances in endoscopic endonasal skull base surgery have led to the development of new routes to areas beyond the midline skull base. Recently, feasible surgical corridors to the lateral skull base have been described. The aim of this study was to describe the anatomical exposure of the ventrolateral brainstem and posterior fossa through an extended endoscopic endonasal transclival transpetrosal and transcondylar approach. Six human heads were used for the dissection process. The arterial and venous systems were injected with red- and blue-colored latex, respectively. A pre- and postoperative computed tomography (CT) scan was carried out on every head. The endoscopic endonasal transclival approach was extended through an anterior petrosectomy and a medial condylectomy. A three-dimensional model of the approach was reconstructed, using a dedicated software, from the overlapping of the pre- and post-dissection CT imaging of the specimen. An extended endoscopic transclival approach allows to gain access through an extradural anterior petrosectomy and medial condylectomy to the anterolateral surface of the brainstem and the posterior fossa. Two main intradural anatomical corridors can be described: first, between the V cranial nerve in the prepontine cistern and the VII–VIII cranial nerves in the cerebellopontine and cerebellomedullary cistern; second, between the VII–VIII cranial nerves and the IX cranial nerve, in the premedullary cistern. Extending the transclival endoscopic approach by performing an extradural anterior petrosectomy and a medial condylectomy provides a safe and wide exposure of the anterolateral brainstem with feasible surgical corridors around the main neurovascular structures.     

Surgical approaches to the cavernous sinus: a microsurgical study

The surgical approaches to the cavernous sinus were examined in 50 adult cadaveric cavernous sinuses using magnification of X3 to X40. The following approaches were examined: 1) the superior intradural approach directed through a frontotemporal craniotomy and the roof of the cavernous sinus; 2) the superior intradural approach combined with an extradural approach for removing the anterior clinoid process and unroofing the optic canal and orbit; 3) the superomedial approach directed through a supraorbital craniotomy and subfrontal exposure to the wall of the sinus adjacent to the pituitary gland; 4) the lateral intradural approach directed below the temporal lobe to the lateral wall of the sinus; 5) the lateral extradural approach for exposure of the internal carotid artery in the floor of the middle cranial fossa proximal to the sinus; 6) the combined lateral and inferolateral approach, in which the infratemporal fossa was opened and the full course of the petrous carotid artery and the lateral wall of the sinus were exposed and; 7) the inferomedial approach, in which the medial wall of the sinus was exposed by the transnasal-transsphenoidal route. It was clear that a single approach was not capable of providing access to all parts of the sinus. The intracavernous structures best exposed by each route are reviewed. The osseous relationships in the region were examined in dry skulls. Anatomic variants important in exposing the cavernous sinus are reviewed.