Extradural Anterior Clinoidectomy Research Articles

Ultra-Early Optic Nerve Decompression for the Resection of Anterior Clinoidal Meningioma.

Improvement in vision is one of the main goals of surgery for anterior clinoidal meningiomas with visual deficits. Early optic nerve decompression surgery has been advocated in previous studies to achieve the best visual outcome. Through this video, the authors describe their surgical techniques to decompress the optic nerve at the very early stage of surgery.A 35-year-old patient presented with subjective blurry vision in the right eye over the last 8 months. Magnetic resonance images showed a 3.2-cm meningioma arising at the right anterior clinoid. Preoperative ophthalmological test was within the normal range, but the patient wished to have surgical resection after a detailed discussion of benefits and risks related to surgical resection. The surgical strategy consisted of the right lateral subfrontal approach that includes a standard right frontotemporal craniotomy, extradural anterior clinoidectomy, and early optic nerve decompression prior to tumor resection. The tumor was divided into compartments defined by the arteries and resected. Simpson grade II resection was achieved without complications. The patient's symptoms disappeared.In anterior clinoidal meningiomas that cause visual deficits, the optic nerve is assumed very vulnerable to any further injuries related to the operative maneuver. Ultra-early optic nerve decompression can be performed in anterior clinoidal meningiomas regardless of their size by extradural unroofing of the optic canal and sectioning of the optic canal sheath, which we believe contributes to better visual improvement. The link to the video can be found at: https://youtu.be/RIFi4ecWAhQ .

Microsurgical Resection of Lateral Tuberculum Sellae Meningioma: Operative Video

Tuberculum Sellae Meningiomas (TSMs) are lesions dramatically related to the optic apparatus once the principal clinical complain remains on visual alterations. This is the main picture on decision making to evaluate the best time, risk-benefit, and surgical approaches to the patient treatment. In this video, we present a 65 years old female with 30 days complaint of unilateral (right) complete blindness and complete impaired right eye field test. On physical examination, there were normal pupillary function to light tests. The scans demonstrated the presence of a TSM mostly related to the right optic nerve and encasing it altogether with the right internal carotid artery. Promptly, surgery was addressed using a modified one piece cranio-orbital-zygomatic approach with extra-dural anterior clinoidectomy, as this is the procedure of choice of the senior author (LB), with easy access to decompression of the optic canal and nerve. As demonstrated on the video, the optic nerve was encased by the tumor and pushed upwards against the falciform ligament. Complete resection and decompression was established with step by step dissection, starting unroofing the optic canal, opening the ligament and finally with carefully tumor debulking. Pathology demonstrated a grade one meningioma. The patient improved remarkably her visual acuity and visual field tests on the postoperative period, emphasizing the importance of early treatment for nerve function outcome. The link to the video can be found at: https://youtu.be/pALZqDUkltQ .

Microsurgical Resection of Tuberculum Sellae Meningioma via Pterional Craniotomy with Extradural Anterior Clinoidectomy and Optic Unroofing.

Microsurgical treatment of suprasellar tumors, in particular tuberculum sellae meningiomas, poses significant challenge. These tumors are surrounded by vital neurovascular structures, such as optic apparatus, pituitary stalk, internal carotid artery and its branches, and anterior cerebral arteries. In large and complex cases, early identification and decompression of these structures may facilitate safer dissection and resection. Therefore, extradural anterior clinoidectomy with optic unroofing facilitates the internal carotid artery exposure and optic nerve decompression. In this video, we describe a 37-year-old female patient who presented with new onset of severe headaches. On visual examination, she was found to have bitemporal visual defects. MRI scan of the head showed a large, approximately 3 cm suprasellar tumor consistent with tuberculum sellae meningioma. She underwent surgical resection via pterional craniotomy with extradural anterior clinoidectomy and optic unroofing. Microsurgical gross total resection was achieved and histopathology was WHO grade II meningioma. She had an uneventful postoperative course and visual field examination improved significantly. In this video, surgical technique in performing extradural anterior clinoidectomy and optic unroofing and steps of microsurgical resection are demonstrated. The link to the video can be found at: https://youtu.be/oPZ8NTyvxJc .

Choice between Intradural and Extradural Anterior Clinoidectomy in Aneurysm Surgery for Paraclinoid Internal Carotid Artery Aneurysm

Choice between Intradural and Extradural Anterior Clinoidectomy in Aneurysm Surgery for Paraclinoid Internal Carotid Artery Aneurysm

Extradural clinoidectomy for resection of clinoidal meningioma.

Extradural anterior clinoidectomy is a versatile technique to increase exposure of the sellar and parasellar region. It is of particular use in the resection of clinoidal meningiomas, as sphenoidal and clinoidal hyperostosis can cause compression of the optic nerve. Extradural clinoidectomy follows a series of steps, consisting of (1) unroofing of the superior orbital fissure, (2) unroofing of the optic canal, (3) removal of the optic strut, and (4) removal of the anterior clinoid process. The authors show these steps in detail, as well as their application to the resection of a large clinoidal meningioma. The video can be found here: https://youtu.be/O1Fcef29ETg .

Histology of the distal dural ring.

The distal dural ring (DDR) is a conserved intracranial anatomic structure marking the boundary point at which the internal carotid artery (ICA) exits the cavernous sinus (CS) and enters the subarachnoid space. Although the CS has been well described in a range of anatomic studies, to our knowledge no prior study has analyzed the histologic relationship between the ICA and DDR. Correspondingly, our objective was to assess the relationship of the DDR to the ICA and determine whether the DDR can be dissected from the ICA and thus divided, or can only be circumferentially trimmed around the artery. The authors examined ten fresh-frozen, adult cadaveric specimens. A standard frontotemporal craniotomy, orbito-optic osteotomy, and extradural anterior clinoidectomy was performed bilaterally. The cavernous ICA, DDR, and supraclinoid ICA were harvested as an en bloc specimen. Specimens formalin-fixed and paraffin-embedded prior to routine histochemical staining with hematoxylin and eosin and Masson trichrome. In all specimens, marked microscopic investment of the DDR throughout the ICA adventitia was noted. Dural collagen fibers extensively permeated the arterial layers superficial to the muscularis propria, with no evidence of a clear separation between the DDR and arterial adventitia. Histologic analysis suggests that the ICA and DDR are highly interrelated, continuous structures, and therefore attempted intraoperative dissection between these structures may carry an elevated risk of injury to the ICA. We correspondingly recommend careful circumferential trimming of the DDR in lieu of direct dissection in cases requiring mobilization of the clinoidal ICA. Clin. Anat. 30:742-746, 2017. © 2017Wiley Periodicals, Inc.

Extradural anterior clinoidectomy: Technical nuances from a learner's perspective

Background:Extradural removal of the anterior clinoid process (ACP) is a crucial step in the proper surgical exposure of various pathologies in and around the central skull base. Since the pioneering description by Dolenc, the technique of extradural clinoidectomy has undergone several refinements in the light of improved understanding of microsurgical anatomy and maturation of neurosurgical techniques. Mastery of the surgical nuances involved in performing this surgical exercise will allow the young neurosurgeon to execute this step without undue reluctance and trepidation.Objective:This paper is an attempt to describe in detail, from a learner's viewpoint, the sequence of maneuvers involved in extradural removal of the ACP.Materials and Methods:The standard pterional approach and extradural anterior clinoidectomy was performed on four sides of two formalin fixed and latex injected cadaver heads. Important steps were photographed through the surgical microscope.Conclusion:An accurate understanding of the microsurgical anatomy of this region and the surgical nuances relevant to extradural clinoidectomy helps simplify the complexity of this surgical step.

The Extended Lateral Supraorbital Approach and Extradural Anterior Clinoidectomy Through a Frontopterio-Orbital Window: Technical Note and Pilot Surgical Series

Lateral approaches to treat anterior cranial fossa lesions have evolved since the first frontotemporal approach described by Dandy in 1918. We describe a less invasive approach to perform extradural anterior clinoidectomy through a lateral supraorbital (LSO) approach for anterior circulation aneurysms and anterolateral skull base lesions. The extended LSO approach involves performing a standard lateral supraorbital craniotomy followed by drilling of the sphenoid wing and lateral wall of the orbit through the frontal bony opening of the LSO approach, without any temporal extension of the craniotomy. This creates a frontopterio-orbital window exposing the periorbita; superior, medial, and anterior aspect of the temporal dura mater; and superior orbital fissure. After unroofing the superior orbital fissure, the meningo-orbital fold is cut, and the temporal dura mater is peeled from the lateral wall of the cavernous sinus to expose the anterior clinoid process allowing a standard opening of the optic canal and anterior clinoidectomy. The extended LSO approach and extradural anterior clinoidectomy allowed access to 4 sphenoid wing/anterior clinoidal meningiomas, 5 anterior circulation aneurysms, 2 temporomesial lesions, and 1 orbital/cavernous sinus abscess. Postoperatively, 2 patients had transient hemiparesis, 2 patients had transient third nerve palsy, and 1 patient had minimal visual field deterioration. All patients had a modified Rankin Scale score ≤1 at 8-week follow-up. The extended LSO approach opens a new route (frontopterio-orbital window) to perform extradural anterior clinoidectomy safely and increases surgical exposure, angles, and operability of a less invasive keyhole craniotomy (LSO approach) to treat anterior cranial fossa lesions.

Operative surgical nuances of modified extradural temporopolar approach with mini-peeling of dura propria based on cadaveric anatomical study of lateral cavernous structures.

Background:Extradural temporopolar approach (ETA) has been modified as less invasive manner and named as trans-superior orbital fissure (SOF) approach with mini-peeling technique. The present study discusses the operative nuances of this modified technique on the basis of cadaveric study of lateral cavernous structures.Methods:In five consecutive cadaveric specimens, we performed an extradural anterior clinoidectomy with mini-peeling of the dura propria to expose the anterior clinoid process entirely. We also investigated the histological characteristics of the lateral cavernous sinus (CS) between the dura propria and periosteal dura at the SOF, foramen rotundum (FR), and foramen ovale (FO) levels, and of each trigeminal nerve division.Results:Coronal histological examination of the lateral wall of the CS showed invagination of the dura propria and periosteal dura into the SOF. In contrast, no such invagination was observed at the levels of the FR and FO. This finding supports the technical rationale of the only skeletonization of the SOF for peeling of the dura propria but not FR. In addition, our modified ETA method needs only minimal dural incision between the SOF and FR where no cranial nerves are present.Conclusion:Our technical modification of ETA may be recommended for surgical treatment of paraclinoid lesions to reduce the risk of intraoperative neurovascular injury.

Surgical Treatment of 127 Paraclinoid Aneurysms with Multifarious Strategy: Factors Related with Outcome

Few reports have been published discussing surgical outcomes of paraclinoid aneurysms using multifarious treatments such as high-flow bypass. We retrospectively analyzed findings from 127 consecutive patients (19 males, mean age at surgery: 56.8 years, range: 19-81 years) at our hospital. The size of aneurysms ranged from 2.7-43.2 mm (mean: 6.9 mm). Extradural anterior clinoidectomy was used to clip small aneurysms. As large or giant aneurysms required a longer temporal occlusion period and often could not undergo simple clipping, high-flow bypass with anterior clinoidectomy or cervical internal carotid ligation was performed to reduce aneurysm blood flow and induce thrombosis. We reviewed a postoperative modified Rankin Scale (mRS), radiographic outcomes, cerebral infarction, and visual disturbance. In addition, we analyzed factors relating to the outcomes and complications, with focus on the aneurysm size, location, and type of surgical treatment. Good outcomes were achieved in all patients, as follows: mRS 0:100, mRS 1:16, mRS 2:11, and mRS 3-6:0. Among the 127 patients, complete exclusion of aneurysm was achieved in 119 cases (93.7%). Postoperative morbidity included ischemic lesions in 11 (8.6%) and visual disturbance in 24 (18.8%). Significant statistical differences were observed between ischemic complication and aneurysm size and location (P = 0.0001) and surgical treatment (P < 0.0001). Surgical treatment of unruptured paraclinoid aneurysm has high efficacy with good outcomes and a high rate of complete exclusion. However, the rate of visual disturbance is relatively high. Careful surgical techniques and intraoperative monitoring are therefore required.

Direct suction decompression and fenestrated clip reconstruction of complex paraclinoid carotid artery aneurysm: operative video and nuances of skull base technique.

Direct microsurgical clipping of complex paraclinoid carotid artery aneuryms remains a formidable technical challenge due to the auneurysm's deep location at the skull base, with adjacent bony anatomy, large size, wide neck, and complex neuroanatomical relationships. In this operative video atlas manuscript, the author demonstrates a step-by-step technique for microsurgical clip reconstruction of a large complex ventral paraclinoid carotid artery aneurysm, using a trapping and direct suction decompression strategy followed by multiple fenestrated clip reconstruction of the internal carotid artery (ICA) via a modified orbitozygomatic approach. The nuances of skull base techniques are illustrated including extradural optic nerve decompression, extradural anterior clinoidectomy, incision of the falciform ligament to untether the optic nerve, and release of the distal durai ring to obtain proximal control. Reconstruction of the ICA and preservation of the anterior choroidal artery were achieved with multiple fenestrated clips. Aneurysm obliteration and patency of flow through the ICA was confirmed on video indocyanine green and catheter angiography. Although novel endovascular strategies continue to evolve, these microsurgical skull base techniques should remain in the surgical armamentarium for treating these complex cranial base vascular lesions. The video can be found here: http://youtu.be/IPS6lslk1ds.

Quantitative analysis of variable extent of anterior clinoidectomy with intradural and extradural approaches: 3-dimensional analysis and cadaver dissection.

Drilling of the anterior clinoid process (ACP) is an integral component of surgical approaches for central and paracentral skull base lesions. The technique to drill ACP has evolved from pure intradural to extradural and combined techniques. To describe the computerized morphometric evaluation of exposure of optic nerve and internal carotid artery with proposed tailored intradural (IDAC) and complete extradural (EDAC) anterior clinoidectomy. We describe a morphometric subdivision of ACP into 4 quadrangles and 1 triangle on the basis of fixed bony landmarks. Computerized volumetric analysis with 3-dimensional laser scanning of dry-drilled bones for respective tailored IDAC and EDAC was performed. Both approaches were compared for the area and length of the optic nerve and internal carotid artery. Five cadaver heads were dissected on alternate sides with intradural and extradural techniques to evaluate exposure, surgical freedom, and angulation of approach. Complete anterior clinoidectomy provides a 2.5-times larger area and 2.7-times larger volume of ACP. Complete clinoidectomy deroofed the optic nerve to an equal extent as by proposed the partial tailored clinoidectomy approach. Tailored IDAC exposes only the distal dural ring, whereas complete EDAC exposes both the proximal and distal dural rings with complete exposure of the carotid cave. Quantitative comparative evaluation provides details of exposure and surgical ease with both techniques. We promote hybrid/EDAC technique for vascular pathologies because of better anatomic orientation. Extradural clinoidectomy is the preferred technique for midline cranial neoplasia. An awareness of different variations of clinoidectomy can prevent dependency on any particular approach and facilitate flexibility.

Cavernous sinus meningiomas: imaging and surgical strategy.

Cavernous sinus (CS) meningiomas which are by definition those meningiomas which originate from the parasellar region are difficult skull base tumors to deal with. For deciding the most appropriate surgical strategy, surgeons need detailed preoperative neuroimaging. The vicinity of the tumor with the vital and highly functional neurovascular structures, tumor extensions into the basal cisterns and skull base structures, and the arterial vascularization and venous drainage pathways, as they shape operative strategy, are important preoperative data to take into account. Thin section CT scan with bone windows, 3D spiral CT reconstruction, MRI, MR angiography, and DSA performed with selective arteriography including late venous phases give those required detailed informations about the tumor and its relation with neurovascular and bony structures. The type of craniotomy and complementary osteotomy and the usefulness of an extradural anterior clinoidectomy with unroofing the optic canal can be decided from preoperative neuroimaging. Data collected also help in determining whether extensive exposure of the middle cranial fossa is necessary to ensure substantial devascularization of the tumor and whether proximal control of the internal carotid artery (ICA) at its intrapetrosal portion might be useful. Study of the capacity of blood supply of the Willis circle is wise for deciding the need and way of performing an extra-intracranial bypass together with tumor removal. Currently the concept of operating only the tumors with extracavernous extensions and to limit resection to only their extracavernous portions is the most accepted way of treating these tumors. It was that strategy that was adopted in the senior author's 220-patient series.Radiosurgery or stereotactic fractionated radiotherapy may complement surgery or can be only reserved for growing remnants.

Extradural Anterior Clinoidectomy as Daily Routine

Extradural Anterior Clinoidectomy as Daily Routine

“Extra-Dural Anterior Clinoidectomy through the Lateral Supraorbital Approach: Surgical Anatomy and Initial Clinical Experience”

“Extra-Dural Anterior Clinoidectomy through the Lateral Supraorbital Approach: Surgical Anatomy and Initial Clinical Experience”

Anterior clinoidectomy

The optic nerve within the optic canal, the parophthalmic segment of the carotid artery, and the oculomotor nerve in the superior orbital fissure all lay against the anterior clinoid process. Bone resection uncovers these structures. For extradural resection of the anterior clinoid process and surrounding bone, two key steps are recommended: bony opening of the superior orbital fissure, and transection of the orbitotemporal periosteal fold. Anterior clinoidectomy is technically challenging. Following a sequence of surgical steps to expose clearly-defined surgical landmarks helps to make this procedure simple and safe. • Pterional craniotomy • Complete extradural anterior clinoidectomy • Slit dura (3 mm) to drain cerebrospinal fluid • Peel dura from orbital roof and lateral wall • Bony opening of superior orbital fissure to use it as surgical corridor • Drilling of optic canal • Transection of orbitotemporal periosteal fold • Hollow anterior clinoid process and piece-meal resection • Transection of falciforme ligament to free optic nerve • Replace falciforme ligament by extradural free pericranial flap.

Endoscopic extradural anterior clinoidectomy and optic nerve decompression through a pterional port

Since the first description of the intradural removal of the anterior clinoid process, numerous refinements and modifications have been proposed to simplify and enhance the safety of the technique. The growing use of endoscopes in endonasal and transcranial approaches has changed the traditional management of many skull base lesions. We describe an endoscopic extradural anterior clinoidectomy and optic nerve decompression through a minimally invasive pterional port. Minimally invasive optic nerve decompression, with endoscopic extradural anterior clinoidectomy, through a pterional keyhole craniotomy was performed on five preserved cadaveric heads. The endoscopic pterional port provided a shorter and more direct route to the anterior clinoid region, and helped avoid unnecessary and extensive bone removal. An extradural approach helped minimize complications associated with infraction of the subdural space and allowed for the maintenance of visibility while drilling with continuous irrigation. Adequate 270° bone decompression of the optic canal was achieved in all specimens. Endoscopic extradural anterior clinoidectomy and optic nerve decompression is feasible through a single minimally invasive pterional port.

The Pterional Approach and Extradural Anterior Clinoidectomy to Clip Paraclinoid Aneurysms

ObjectiveThe surgical clipping of paraclinoid segment internal carotid artery aneurysms is considered difficult because of the complex anatomical location and important neighboring structures. Our experiences of pterional craniotomy and extradural anterior clinoidectomy (EAC) to clip paraclinoid aneurysms are reported herein.MethodsWe present two patients with paraclinoid aneurysms who underwent surgical clipping using pterional craniotomy and EAC. The clinical results and operative techniques were reviewed from the patients' medical records.ResultsEAC improves the surgical field in the suprasellar and periclinoid regions. Clinically, a good outcome was obtained in both cases. No surgical complications directly resulting from the EAC were observed.ConclusionFavorable surgical results can be obtained with pterional craniotomy and EAC for the clipping of paraclinoid aneurysms. EAC is advocated for the clipping of paraclinoid aneurysms.

Measurement of Critical Structures around Paraclinoidal Area : A Cadaveric Morphometric Study.

ObjectiveAlthough removal of the anterior clinoid process (ACP) is essential surgical technique, studies about quantitative measurements of the space broadening by the anterior clinoidectomy are rare. The purposes of this study are to investigate the dimension of the ACP, to quantify the improved exposure of the parasellar space after extradural anterior clinoidectomy and to measure the correlation of each structure around the paraclinoidal area.MethodsEleven formalin-fixed Korean adult cadaveric heads were used and frontotemporal craniotomies were done bilaterally. The length of C6 segment of the internal carotid artery on its lateral and medial side and optic nerve length were checked before and after anterior clinoidectomy. The basal width and height of the ACP were measured. The relationships among the paraclinoidal structures were assessed. The origin and projection of the ophthalmic artery (OA) were investigated.ResultsThe mean values of intradural basal width and height of the ACP were 10.82 mm and 7.61 mm respectively. The mean length of the C6 lateral and medial side increased 49%. The mean length of optic nerve increased 97%. At the parasellar area, the lengths from the optic strut to the falciform liament, distal dural ring, origin of OA were 6.69 mm, 9.36 mm and 5.99 mm, respectively. The distance between CN III and IV was 11.06 mm.ConclusionWith the removal of ACP, exposure of the C6 segments and optic nerve can expand 49% and 97%, respectively. This technique should be among a surgeon's essential skills for treating lesions around the parasellar area.

安全で正確な脳動脈瘤クリッピングのための手術解剖の確認と正常構造の温存─無血術野の獲得と強拡大下操作─

The skills of skull-base drilling and cerebral revascularization are now essential in open surgery for cerebral aneurysms. For this purpose, achieving a bloodless operative field, and identifying and preserving the normal anatomical structures are imperative. We propose the effectiveness of creating a bloodless operative field and operating under a high magnetic field by presenting four common approaches for aneurysm surgery: the transsylvian approach; interhemispheric approach; extradural anterior clinoidectomy; and lateral suboccipital approach. Here we show how we achieve our preferred operative field and present our operative figures. For safe, high-quality clipping of cerebral aneurysms, vascular surgeons should create a bloodless operative field, adjust to surgery under a high magnetic field and train hard for skull-base drilling by attending cadaver courses.