Bone anatomic variations of the parasellar region and its technical implications in para clinoid and posterior communicating segment aneurysms microsurgical clipping - Technical note.

Background: Microsurgical treatment of paraclinoid aneurysms is a complex task that generally requires anterior clinoid process (ACP) removal to obtain adequate surgical exposure. This procedure poses a considerable technical difficulty due to the association of the ACP to critical neurovascular structures. Furthermore, anatomical variations in the parasellar region, such as the caroticoclinoid foramen (CCF) or an interclinoid bridge (ICB), may impose additional challenges and increase surgical complications. The present study aims to briefly review some anatomic variations in the parasellar region and describe a step-by-step surgical technique for a hybrid anterior clinoidectomy based on the senior author's experience. Methods: We present two cases with bone variations on the parasellar region in patients with a paraclinoid aneurysm and another with a posterior communicating segment aneurysm treated by microsurgical clipping at our hospital. Results: We focused on safely dealing with these variations during surgery, without further complications, and with good postoperative results. Patients were discharged with no significant deficit. Postoperative control, computed tomography angiography showed complete exclusion of aneurysms. Conclusion: Although anatomical variations in the parasellar region can complicate surgical clipping of these aneurysms, it is essential to ensure the best possible surgical outcome to conduct thorough preoperative and radiological evaluations.

Cadaveric Sheep Head Model for Anterior Clinoidectomy in Neurosurgical Training.

BACKGROUND: Anterior clinoidectomy is an important procedure used in the treatment of a range of diseases of the frontotemporal region, both vascular and tumoral. Mastering this technique requires a high level of manual skills training. The objective of the study was to describe an easily accessible and economical alternative model of anterior clinoidectomy, with a principal focus on the significance of mastering technical skills and training tactile feedback. METHODS: Five cadaveric sheep heads (10 sides) fixed in formalin and alcohol were injected with silicone and used to simulate extradural (5 sides) and intradural (5 sides) routes and 1 head was used to prepare an anatomic specimen for better demonstration of the anatomy of the paraclinoid region. RESULTS: A comparative anatomic analysis between the ovine and human anterior clinoid process was performed. Using cadaveric sheep models, all principal steps of the procedure for both the extradural and the intradural routes were imitated. CONCLUSIONS: A cadaveric sheep head model serves as a good model of anterior clinoidectomy regarding manual skills training and can serve as a good alternative to human cadaveric training.

Optic Foraminotomy for Clipping of Superior Carotid-Ophthalmic Aneurysms.

Background: Carotid-ophthalmic aneurysms usually cause visual problems. Its surgical treatment is challenging because of its anatomically close relations to the optic nerve, carotid artery, ophthalmic artery, anterior clinoid process, and cavernous sinus, which hinder direct access. Despite recent technical advancements enabling risk reduction of this complication, postoperative deterioration of visual function remains a significant problem. Therefore, the goal of preserving and/or improving the visual outcome persists as a paramount concern. Objective: We propose optic foraminotomy as an alternative microsurgical technique for dorsal carotid-ophthalmic aneurysms clipping. As a secondary objective, the step by step of that technique and its benefits are compared to the current approach of anterior clinoidectomy. Methods: We present as an example two patients with superior carotid-ophthalmic aneurysms in which the standard pterional craniotomy, transsylvian approach, and optic foraminotomy were performed. Surgical techniques are presented and discussed in detail with the use of skull base dissections, microsurgical images, and original drawings. Results: Extensive opening of the optic canal and optic nerve sheath was successfully achieved in all patients allowing a working angle with the carotid artery for correct visualization of the aneurysm and further clipping. Significant visual acuity improvement occurred in both patients because of decompression of the optic nerve. Conclusion: Optic foraminotomy is an easy and recommended technique for exposing and treating superior carotid-ophthalmic aneurysms and allowing optic nerve decompression during the first stages of the procedure. It shows several advantages over the current anterior clinoidectomy technique regarding surgical exposure and facilitating visual improvement.

Intra- and extradural anterior clinoidectomy: anatomy review and surgical technique step by step.

PURPOSE: The complex relations of the paraclinoid area make the surgical management of the pathology of this region a challenge. The anterior clinoid process (ACP) is an anatomical landmark that hinders the visualization and manipulation of the surrounding neurovascular structures, hence in certain surgical interventions might be necessary to remove it. We reviewed the anatomical relationships that involve the paraclinoid area and detailed the step-by-step techniques of intra and extradural clinoidectomy in cadaveric specimens. MATERIALS AND METHODS: A literature review was done describing the most relevant anatomic relationships regarding the anterior clinoid process. Extradural and intradural clinoidectomy techniques were performed in six dry bone heads and in ten previously injected cadaverous specimens with colored latex (Sanan et al. in Neurosurgery 45:1267-1274, 1999) and each step of the procedure was recorded using photographic material. Finally, an analysis of the anatomical exposure achieved in each of the techniques used was performed. RESULTS: The main advantage of the intradural clinoidectomy technique is the direct visualization of the neurovascular structures adjacent to the ACP when drilling, at the same time, opening the Sylvian fissure will allow the direct visualization of the ACP variants. The main advantage offered by the extradural technique is that the dura protects adjacent eloquent structures while drilling. Among the disadvantages, it is noted that the same dura that would protect the underlying structures also prevents the direct visualization of these neurovascular structures adjacent to the ACP. CONCLUSION: We reviewed the anatomy of the paraclinoid area and made a step-by-step description of the technique of the anterior clinoidectomy in its intra- and extradural variants in cadaveric preparations for a better understanding.

Anterior Clinoidectomy: Intradural Step-by-Step En Bloc Removal Technique.

OBJECTIVE: Anterior clinoidectomy is an important and essential skill for skull base and cerebrovascular neurosurgeons. We present a 1-piece intradural anterior clinoidectomy, providing a step-by-step description of the technique, independently of anatomic variations. METHODS: Between 2014 and 2020, 128 patients (119 women and 9 men; average age, 54.6 years) underwent intradural anterior clinoidectomy during microsurgical clipping of carotid-ophthalmic aneurysms. RESULTS: The anterior clinoid process continues medially with the planum sphenoidale, over the optic nerve, laterally with the lesser wing of the sphenoid bone, and inferiorly with the optic strut, which is always found anteriorly to the clinoid segment of the internal carotid artery, and separates the optic canal from the superior orbital fissure. The proposed anterior clinoidectomy followed, one after the other, these 3 fixation points for the detachment of the anterior clinoid process. The main indication for intradural anterior clinoidectomy was the management of vascular lesions around paraclinoid (clinoidal and ophthalmic) segments of the internal carotid artery. Complications of the procedure included injury to the internal carotid artery or the ophthalmic artery, thermal damage to the optic nerve, and invasion of the sphenoid sinus or a pneumatized anterior clinoid process, which could lead to postoperative cerebrospinal fluid leakage. CONCLUSIONS: The anterior clinoidectomy technique described here minimizes the drilling surface for detachment of the anterior clinoid process and reduces operative time as well as the amount of bone dust produced by drilling. It also precisely delineates the localization of the optic strut, preventing carotid or optic nerve damage.

Orbitomeningeal Band in Transcavernous Dissection and Anterior Clinoidectomy: 3-Dimensional Operative Video.

The orbitomeningeal or meningo-orbital band (MOB) has been described as the most superficial dural band responsible for tethering the frontotemporal basal dura to the periorbita.1,2 The MBO usually interferes with the surgical approach to the most profound areas of the anterior and middle skull base. It is known that there are no cranial nerves on the lateral surface of the superior orbital fissure; therefore, the neurosurgeon can cut the MOB without causing any neurological deficit and, at the same time, achieving fully exposure of the anterior clinoid process1-4 and/or the lateral wall of the cavernous sinus.5 The purpose of this video is to describe the microsurgical anatomy of the MOB and illustrate the technique for its detachment, accompanied by 2 illustrative cases. To achieve this, we use 3-dimensional recordings of 2 cadaveric specimens' dissections performed by the senior author. Case 1: 58-yr-old female with left blindness. Magnetic resonance imaging (MRI) shows an anterior and middle skull base lesion with orbital compression. Case 2: 32-yr-old male presenting with headache and trigeminal neuralgia. The MRI revealed an hourglass-shaped lesion in the posterior and middle fossa. Both patients signed an informed consent and agree with the use of their images for research purposes. We used a step-by-step approach for an adequate and secure dissection of the MOB highlighting the anatomic structures involved in the process. This approach allows safe and adequate access to the deeper structures of the anterior and middle skull base.

Pterional Craniotomy for Resection of Clinoidal Meningioma Associated With an Aerated Anterior Clinoid Process: 2-Dimensional Operative Video.

Extradural removal of the clinoid performed prior to resection of clinoidal meningiomas has been advocated as a way to facilitate devascularization of the tumor and provide early identification and/or decompression of adjacent neurovascular structures. A small number of video publications exist in the literature that provides useful guidance to surgeons preparing for resection of clinoidal region meningiomas.1-3 However, none of these videos portray the variable anatomy associated with an aerated clinoid process. This known anatomical variant can increase the risk profile associated with resection of clinoidal meningomas-especially with regards to postoperative cerebrospinal fluid (CSF) fistula. In this video publication, we discuss the care of a 54 yr-old male who presented with visual deterioration in the right eye. Magnetic resonance imaging (MRI) revealed findings consistent with a right clinoidal meningioma. Computed tomography demonstrated bilateral aeration of the anterior clinoid processes. The patient was taken to the operating room for right pterional craniotomy for resection of the neoplasm. Edited, intraoperative 2-dimensional-video demonstrates the variable anatomy encountered during removal of an aerated clinoid process. Relevant steps associated with subsequent tumor resection are summarized. Following resection, MRI obtained in the early postoperative period demonstrated gross total resection of the neoplasm without untoward finding. The patient noted marked improvement in his vision following surgery and did not suffer any complications relating to postoperative CSF fistula. Full patient consent for photography and/or recording of other forms of video/imaging was obtained in the preoperative period.

The extradural minipterional pretemporal approach for the treatment of spheno-petro-clival meningiomas.

BACKGROUND: Cavernous sinus and petroclival region is an anatomically complex region in close relationship with important neurovascular structures. As such, the surgical treatment of spheno-petro-clival (SPC) meningiomas represents an operative challenge, in which several routes and its combinations might be used. METHODS: We describe in detail the surgical technique of the extradural minipterional pretemporal approach (eMPT-P) to the SPC region and highlight the main anatomical key elements involved in this approach as well as the technical aspects for avoiding surgical complications. CONCLUSION: The eMPT-P is a versatile approach that uses the extradural route, and thereby reduces brain retraction, while provides a good angle of exposure of the SPC region.

Technical Description of Minimally Invasive Extradural Anterior Clinoidectomy and Optic Nerve Decompression. Study of Feasibility and Proof of Concept.

BACKGROUND: Several diseases that involve the optic canal or its contained structures may cause visual impairment. Several techniques have been developed to decompress the optic nerve. OBJECTIVE: To describe minimally invasive extradural anterior clinoidectomy (MiniEx) for optic nerve decompression, detail its surgical anatomy, present clinical cases, and established a proof of concept. METHODS: Anatomic dissections were performed in cadaver heads to show the surgical anatomy and to show stepwise the MiniEx approach. In addition, these surgical concepts were applied to decompress the optic nerve in 6 clinical cases. RESULTS: The MiniEx approach allowed the extradural anterior clinoidectomy and a nearly 270° optic nerve decompression using the no-drill technique. In the MiniEx approach, the skin incision, dissection of the temporal muscle, and craniotomy were smaller and provided the same extent of exposure of the optic nerve, anterior clinoid process, and superior orbital fissure as that usually provided by standard techniques. All patients who underwent operation with this technique had improved visual status. CONCLUSIONS: The MiniEx approach is an excellent alternative to traditional approaches for extradural anterior clinoidectomy and optic nerve decompression. It may be used as a part of more complex surgery or as a single surgical procedure.

Clinoidectomía anterior intradural para clipado de aneurisma paraclinoideo izquierdo: video quirúrgico / Anterior intradural clinoidectomy for clipping left paraclinoid aneurysm: surgical video

Introducción: Los aneurismas paraclinoideos representan un verdadero desafío microquirúrgico para su resolución. Objetivo: Presentamos el caso de una mujer de 43 años de edad con cefalea, detectando en angiografía aneurisma paraclinoideo izquierdo. Material y métodos: Se realizó abordaje pterional izquierdo y exposición de carótida interna a nivel cervical, durotomía arciforme con apertura de cisterna silviana hacia cisterna carotídea. Se expone la apófisis clinoides anterior, observándose en el video, el aneurisma naciendo del segmento clinoideo de la arteria carótida interna, siendo imposible el clipado de la misma sin clinoidectomía anterior. Se secciona la duramadre desde medial respecto al conducto óptico hasta la apófisis clinoides. Se realiza fresado en la base de la apófisis clinoides para exponer el anillo dural distal. Se libera la carótida en el segmento clinoideo a través de la sección del anillo dural distal para poder movilizarla. Identificado el cuello distal y proximal del aneurisma, se comienza la reconstrucción colocando un clip a 90° en dirección anteroposterior, un segundo clip en dirección posteroanterior y al punzar el aneurisma se constata flujo aneurismático presente. Se coloca un tercer y cuarto clip en tándem desde la proximidad a la carótida interna hacia el domo del aneurisma. Finalmente se posiciona un quinto clip curvo sobre los anteriores para darles mayor presión de cierre. Resultados: Se observa angiografía postoperatoria con exclusión completa el aneurisma con adecuada permeabilidad carotidea. El período postoperatorio fue excelente, sin déficit neurológico. La paciente brindo consentimiento para publicar sus imágenes y videos.

Introduction: Paraclinoid aneurysms represent a true microsurgical challenge. Objective: We present the case of a 43-year-old woman with headache, in whom a left paraclinoid aneurysm was detected by angiography. Methods and Materials: A left pterional approach was adopted, combined with exposing the internal carotid artery at the cervical level, and an arciform durotomy with the opening of the sylvian fissure to the carotid cistern. The anterior clinoid process was exposed, revealing the aneurysm originating from the clinoid segment of the carotid artery; consequently, clipping was impossible without an anterior clinoidectomy. The dura was cut medially from the optic canal to the clinoid process. Drilling was performed at the base of the clinoid process to expose the distal carotid dural ring. The carotid was released in the clinoid segment by sectioning the distal dural ring to mobilize it. After identifying the distal and proximal neck of the aneurysm, reconstruction was initiated by placing a 90-degree clip in the anteroposterior direction; then, a second clip in the posteroanterior direction and puncturing the aneurysm, demonstrating that aneurysmal flow was present. Third and fourth clips were placed in tandem, one proximal to the internal carotid and the other at the dome of the aneurysm. Finally, a fifth curved clip was placed over the previous clips to increase their closure pressure. Results: Postoperative angiography revealed complete exclusion of the aneurysm with adequate carotid permeability. The postoperative period lacked any complications or neurological deficits. The patient consented to have her images and videos published. Conclusions: Combining a left pterional approach with exposing the internal carotid artery at the cervical level and performing an arciform durotomy at the sylvian fissure's opening into the carotid cistern, an angiographically-detected left paraclinoid aneurysm was treated successfully with an excellent outcome.

Aneurismas paraclinoideos: experiencia personal de 1 año en el Hospital Regional de Temuco / Paraclinoid aneurysm: 1 year personal experience at Hospital Regional de Temuco

Se presenta la experiencia personal en el tratamiento de 5 pacientes con 7 aneurismas paraclinoideos tratados quirúrgicamente en el Hospital Regional Temuco durante junio de 2015 y julio de 2016 (13 meses). Todos los pacientes fueron previamente discutidos con neurorradiologo Intervencional local y considerados no favorables para terapia endovascular. En todos ellos se realizó una craneotomía mini pterional con clinoidectomía extradural y exposición de la arteria carótida interna cervical. Cuatro pacientes consultaron con hemorragia subaracnoidea y requirieron cirugía cerebral de urgencia. En 6 aneurismas se realizó clipaje y en 1 trapping. Cuatro pacientes no tuvieron deterioro neurológico y evolucionaron favorablemente mientras que 1 paciente falleció por hipoperfusión secundario al trapping de la carótida supraclinoidea. Se enfatiza el manejo interdisciplinario, el plan preoperatorio y el conocimiento de la neuroanatomía en el tratamiento de esta patología.

A personal experience is presented in treating 5 patients with 7 paraclinoid aneurysm who underwent surgery at Hospital Regional Temuco between june 2015 and july 2016 (13 months). All patients were previously discussed with local interventional neuroradiologist considering them not favorable to endovascular therapy. Mini pterional craniotomy with extradural clinoidectomy and internal cervical carotid artery exposure was performed in all of them. 4 patients presented with subarachnoid hemorrhage and required urgent brain surgery. Direct clipping was optimal in 6 aneurysm and 1 was treated with trapping. 4 patients had no neurological deteriotation with excellent outcome and 1 patient died because of hypoperfusion secondary to the supraclinoid carotid trapping. Interdisciplinary management, preoperative planning and neuroanatomy knowledge are emphasized in order to treat this pathology.

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.