Anterior clinoidectomy in low lying internal carotid artery-posterior communicating artery aneurysm.

BACKGROUND: At times, a regulation internal carotid artery-posterior communicating artery junction (ICA-P-Comm) aneurysm becomes a surgical hurdle owing to its close proximity to the anterior clinoid process, an immovable ICA and a concealed dominant P-Comm artery arising from the aneurysm neck. METHOD: A 70 year old patient with a low lying ICA-P-Comm aneurysm underwent a "tailored" intradural clinoidectomy for aneurysm clipping. CONCLUSION: A tailored anterior clinoidectomy to expose "just enough" allows a proximal ICA control in a suitable area, mobility of an atherosclerotic ICA and exposes the P-Comm artery origin which are essential in safe clipping of these aneurysms.

Assessment of the Anterior Clinoid Process and Optic Strut in Chiari Malformation Type I: A Computed Tomography Study.

Objective This study aimed to evaluate morphological features of the anterior clinoid process (ACP) and the optic strut (OS) in Chiari malformation Type I (CM-I). Methods The study universe consisted of computed tomography images of 41 CM-I patients and 45 normal subjects. Comparison of the parameters for CM-I and the control group was performed with the Student's t -test. A " p < 0.05" was accepted as the significance level. Results ACP length was smaller in CM-I than the control group ( p < 0.001). In contrast to ACP length, ACP angle ( p < 0.001), OS length ( p = 0.022), and the distance between ACP and OS ( p = 0.020) were found greater in CM-I in comparison to the control group ( p < 0.05). ACP width ( p = 0.233) and OS width ( p = 0.376) were similar in both groups. ACP pneumatization in CM-I group was found as 12.20%, whereas in the control group as 8.90%. Two different types about the pneumatization were identified in CM-I group (Type 1: 4.9% and Type 2: 7.3%), whereas three different types in the control group (Type 1: 3.3%, Type 2: 4.4%, and Type 3: 1.1%). Relative to ACP, three different types about OS position were identified in CM-I group (Type C: 31.70%, Type D: 64.60%, and Type E: 3.70%) and the control group (Type C: 7.80%, Type D: 64.40%, and Type E: 27.80%). Conclusion Shorter ACP, wide-angled ACP, longer OS, and more anteriorly located OS were found in CM-I group compared with the normal group. Our findings showed that the pneumatization of ACP was not affected by CM-I.

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.

Exoscopic extradural anterior clinoidectomy.

Extradural anterior clinoidectomy is a resourceful technique to decompress the optic nerve as well as increase exposure of the parasellar region during extensive approaches. Despite requiring adjunctive epidural bone work, this technique allows safe optic nerve mobilization and early devascularization for anterior clinoidal meningioma resection. This 2D operative video describes right optic nerve decompression by extradural anterior clinoidectomy and subsequent resection of a right Al-Mefty type III clinoid meningioma under exoscope magnification. The patient was a 50-year-old woman with a 1-year history of right visual acuity impairment and papillary atrophy. The exoscope allows a 360° view around the anterior clinoid, improving maneuverability. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23118.

Feasibility and efficacy of endoscopic transorbital optic canal decompression for meningiomas causing compressive optic neuropathy.

OBJECTIVE: The endoscopic transorbital approach (ETOA) and transorbital anterior clinoidectomy have been suggested as novel procedures through which to reach the superolateral compartments of the orbit, allowing optic canal decompression. However, there is limited literature describing the technical details and surgical outcomes of these procedures. In this study, the authors aimed to analyze the feasibility and efficacy of endoscopic transorbital decompression of the optic canal through anterior clinoidectomy for compressive optic neuropathic lesions. METHODS: Between 2016 and 2022, the authors performed ETOA for compressive optic neuropathic lesions in 14 patients. All these patients underwent transorbital anterior clinoidectomy through the surgically defined "intraorbital clinoidal triangle," which is composed of the roof of the superior orbital fissure, the medial margin of the optic canal, the medial border of the superior orbital fissure, and the optic strut. Demographic data, tumor characteristics, pre- and postoperative imaging, pre- and postoperative visual examinations, and surgical outcomes were retrospectively reviewed. RESULTS: The mean age at the time of ETOA was 53.3 years (range 41-64 years), and the mean follow-up was 16.8 months (range 6.7-51.4 months). The inclusion criterion in this study was having a meningioma (14 patients). In the preoperative visual function examination, 7 patients with a meningioma showed progressive visual impairment. After endoscopic transorbital optic canal decompression, visual function improved in 5 patients, remained unchanged in 8 patients, and worsened in 1 patient. No new-onset neurological deficit was associated with ETOA and anterior clinoidectomy in any patients. CONCLUSIONS: Endoscopic transorbital decompression of the optic canal with extradural anterior clinoidectomy is a safe and feasible technique that avoids significant injury to the clinoidal internal carotid artery and surrounding neurovascular structures.

Cranioorbital Pretemporal Skull Base Approach with Anterior Clinoidectomy for Removal of Large Left Clinoid Meningioma: "Unwrapping" Encircled Internal Carotid Artery and Decompressing Optic Nerve: 2-Dimensional Operative Video.

Clinoidal meningiomas are meningiomas arising from or in the vicinity of the anterior clinoid process.1 Despite advanced microsurgical techniques, clinoidal meningiomas remain challenging.2 Extradural anterior clinoidectomy with optical unroofing remains an important tool in skull base surgery, which provides a safe operative corridor, facilitating greater extent of resection and enhancing overall outcome, particularly visual function.2-13 A 66-year-old woman presented with history of visual disturbances. Magnetic resonance imaging revealed a dural-based tumor consistent with a large left clinoidal meningioma, with tumor wrapping (encircling) around the left trunk and internal carotid artery (ICA) bifurcation, elevating the left middle cerebral artery M1 segment, and invading the left optic canal. Left cranio-orbital craniotomy with pretemporal exposure was used (Video 1).1,9 A high-speed diamond drill with irrigation completed the extradural anterior clinoidectomy and optical canal unroofing. Use of a 1-mm Kerrison rongeur should be done with utmost care. The tumor was unwrapped via meticulous piecemeal removal. Final dissection and ICA unwrapping was done when the tumor was debulked enough that dissecting it off the artery was safe and under less tension. Due to its obscurity, final decompression of the left optic nerve with incision and opening of the falciform ligament was performed at the end of the procedure.10 Postoperative neuro-ophthalmologic examination showed a grossly unchanged left visual field with some visual acuity improvement. Resection of tumor encircling the ICA has been described previously;14 however, to the best of our knowledge, this is the first video describing removal of a tumor surrounding the ICA (perfomed by senior author K.I.A.), essentially "unwrapping" the left ICA trunk and its bifurcation. The patient consented to publication.

The Usefulness of Extradural Anterior Clinoidectomy for Lower-Lying Posterior Communicating Artery Aneurysms : A Cadaveric Study.

Objective: To confirm the usefulness of the extradural anterior clinoidectomy during the clipping of a lower riding posterior communicating artery (PCoA) aneurysm through cadaver dissection. Methods: Anatomic measurements of 12 adult cadaveric heads (24 sides total) were performed to compare the microsurgical exposure of the PCoA and internal carotid artery (ICA) before and after clinoidectomy. A standard pterional craniotomy and transsylvian approach were performed in all cadavers. The distance from the ICA bifurcation to the origin of PCoA (D1), pre-anterior clinoidectomy distance from the ICA bifurcation to tentorium (D2), post-anterior clinoidectomy distance from the ICA bifurcation to tentorium (D3), pre-anterior clinoidectomy distance from the tentorium to the origin of PCoA (D4) and post-anterior clinoidectomy distance from the tentorium to the origin of PCoA (D5) and the distance of the ICA obtained after anterior clinoidectomy (D6) were measured. We measured the precise thickness of the blade for the Yasargil clip with a digital precision ruler to confirm the usefulness of the extradural anterior clinoidectomy. Results: Twenty-four sites were dissected from 12 cadavers. The age of the cadavers was 79.83±6.25 years. The number of males was the same as the females. The space from the proximal origin of the PCoA to the preclinoid-tentorium (D4) was 1.45±1.08 mm (max: 4.01, min: 0.56). After the clinoidectomy, the space from the proximal origin of the PCoA to the postclinoid-tentorium (D5) was 3.612±1.15 mm (max: 6.14, min: 1.83). The length (D6) of the exposed proximal ICA after the extradural clinoididectomy was 2.17±1.04 mm on the lateral side and 2.16±0.89 mm on the medial side. The thickness of the Yasargil clip blade used during the clipping surgery was 1.35 mm measured with a digital precision ruler. Conclusion: The proximal length obtained by performing an external anterior clinoidectomy is about 2 mm, sufficient for proximal control during PCoA aneurysm surgery, considering the thickness of the aneurysm clips. In a subarachnoid hemorrhage, performing an extradural anterior clinoidectomy could prevent a devastating situation during PCoA aneurysm clipping.

Pterional Craniotomy With Anterior Clinoidectomy for the Resection of a Sphenoid Ridge Meningioma: A Case Report and Two-Dimensional Operative Video.

The pterional craniotomy with anterior clinoidectomy is a surgical technique used to resect sphenoid ridge meningiomas. It involves drilling the bone of the anterior clinoid process to gain access to the skull base, including the cavernous sinus and petrous apex particularly. This approach offers several advantages, including excellent exposure of the surgical site, minimal brain retraction, and the ability to visualize and protect critical neurovascular structures. We present a case of a 59-year-old woman presented with headache, dizziness, blurry vision, and unsteady gait for several months. The brain magnetic resonance imaging with gadolinium contrast showed a large space-occupying homogeneously-enhancing lesion at the left skull base, displacing the surrounding structures, including the frontal lobe, temporal lobe, and brainstem. Herein, we present the intraoperative video on a case in which the pterional craniotomy with anterior clinoidectomy that can allow the exposure and resection of the tumor extending into the posterior fossa was utilized for the resection of a large left sphenoid ridge meningioma with brain stem compression.

A Six-Surface System to Describe Anatomy of Anterior Clinoid Process and Its Application in Anterior Clinoidectomy and Resection of Paraclinoid Meningioma.

OBJECTIVE: The anterior clinoid process (ACP) is surrounded by nerves and vessels that, together, constitute an intricate anatomical structure with variations that challenges the performance of individualized anterior clinoidectomy in treating lesions with different extents of invasion. In the present study, we established a 6-surface system for the ACP based on anatomical landmarks and analyzed its value in guiding ACP drilling and resection of paraclinoid meningiomas. METHODS: Using the anatomical characteristics of 10 dry skull specimens, we set 9 anatomical landmarks to delineate the ACP into 6 surfaces. Guided by our 6-surface system and eggshell technique, 5 colored silicone-injected anatomical specimens were dissected via a frontotemporal craniotomy to perform anterior clinoidectomy. Next, 3 typical cases of paraclinoid meningioma were selected to determine the value of using our 6-surface system in tumor resection. RESULTS: Nine points (A-H and T) were proposed to delineate the ACP surface into frontal, temporal, optic nerve, internal carotid artery, cranial nerve III, and optic strut surfaces according to the adjacent tissues. Either intradurally or extradurally, the frontal and temporal surfaces could be identified and drilled into depth, followed by skeletonization of the optic nerve, cranial nerve III, internal carotid artery, and optic strut surfaces. After the residual bone was removed, the ACP was drilled off. In surgery of paraclinoid meningiomas, our 6-surface system provided great benefit in locating the dura, nerves, and vessels, thus, increasing the safety of opening the optic canal and relaxing the oculomotor or optic nerves and allowing for individualized ACP drilling for meningioma removal. CONCLUSIONS: Our 6-surface system adds much anatomical information to the classic Dolenc triangle and can help neurosurgeons, especially junior ones, to increase their understanding of the paraclinoid spatial structure and accomplish individualized surgical procedures with high safety and minimal invasiveness.

Staged Strategies to Deal with Complex, Giant, Multi-Fossa Skull Base Tumors.

Given the complex and multifaceted nature of resecting giant tumors in the anterior, middle, and, to a lesser extent, the posterior fossa, we present two example strategies for navigating the intricacies of such tumors. The foundational premise of these two approaches is based on a two-stage method that aims to improve the visualization and excision of the tumor. In the first case, we utilized a combined endoscopic endonasal approach and a staged modified pterional, pretemporal, with extradural clinoidectomy, and transcavernous approach to successfully remove a giant pituitary adenoma. In the second case, we performed a modified right-sided pterional approach with pretemporal access and extradural clinoidectomy. This was followed by a transcortical, transventricular approach to excise a giant anterior clinoid meningioma. These cases demonstrate the importance of performing staged operations to address the challenges posed by these giant tumors.

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.

Tailored frontotemporoorbitozygomatic (FTOZ) craniotomy for a large anterior clinoidal meningioma.

Large anterior clinoidal meningiomas are tumors that arise on the anterior clinoid often compressing and encasing the nearby neurovascular structures such as the carotid artery and the optic nerve. These remain as very challenging cases for neurosurgeons because of the issues concerning preservation of critical structures and gross total excision. In this video submission, we will show a case of a large anterior clinoidal meningioma through a tailored frontotemporoorbitozygomotic craniotomy with emphasis on anterior clinoidectomy and the different corridors that can be obtained by this particular approach. The methodical dissection of the tumor and the other critical structures can also be seen.

Advantages of Extradural Anterior Clinoidectomy and Extradural Approach with Dural Incision for Blood Blister Aneurysm or Pseudoaneurysm in the Internal Carotid Artery: Two Case Reports.

Blood blister aneurysms (BBAs) or pseudoaneurysms (PAs) in the internal carotid artery (ICA) have fragile necks; therefore, conventional neck clipping is difficult. The standard treatment for BBAs or PAs is trapping with high or low flow bypass. However, there is no consensus on whether or not anterior clinoidectomy should be performed together. Two patients with ruptured ICA PA (anterior protrusion) or BBA (posterior protrusion) were presented to our hospital. Complete trapping was safely performed for both types of aneurysms via extradural anterior clinoidectomy and the extradural approach with dural incision. The advantages of the procedure are 1) safe proximal clipping, 2) early identification of the ICA C3 portion, 3) minimized frontal lobe retraction, 4) optic canal opening to allow mobility of the optic nerve, and 5) dural ring incision to allow mobility of the ICA.

Modified extradural selective anterior clinoidectomy leaving the optic canal unopened for internal carotid aneurysms: A technical note.

Background: Anterior clinoidectomy is an established procedure used to decompress the optic nerve, mobilize the internal carotid artery (ICA), or enlarge the retrocarotid space. However, its use carries the risk of optic nerve injury. In certain surgeries, such as those for internal carotid aneurysms, propose modification to the anterior clinoidectomy for enlarging the retrocarotid space, especially in operations for ICA aneurysms. Methods: After the anterior clinoid process (ACP) is sufficiently exposed, the internal cancellous bone or pneumatization can be removed through a small window created at its lateral edge to reveal the compact bone of the optic canal. Since the compact bone of the inferior surface facing the ICA is absent or very thin, the ACP can be removed by drilling through the anchoring compact bone with the optic canal in direct sight. Results: In 10 consecutive internal carotid aneurysm cases, the ACP was successfully removed without opening of the optic canal to enlarge the retrocarotid space. Conclusions: Anterior clinoidectomy can be performed to enlarge the retrocarotid space without opening the optic canal from outside the dura.

How I do it: The microsurgical clipping of the giant paraclinoid aneurysm using the retrograde suction decompression technique.

BACKGROUND: Paraclinoid aneurysms account for 5.4% of all intracranial aneurysms. Giant aneurysms are found in 49% of these cases. The 5-year cumulative rupture risk is 40%. Microsurgical treatment of paraclinoid aneurysms is a complex challenge that requires a personalized approach. METHOD: Extradural anterior clinoidectomy and optic canal unroofing were performed in addition to orbitopterional craniotomy. Falciform ligament and distal dural ring transection provided the internal carotid artery and optic nerve mobilization. Retrograde suction decompression was used to soften the aneurysm. Clip reconstruction was performed using tandem angled fenestration and parallel clipping techniques. CONCLUSION: Orbitopterional approach with extradural anterior clinoidectomy combined with retrograde suction decompression technique is a safe and effective modality for treatment of giant paraclinoid aneurysms.

Optic Foraminotomy versus Anterior Clinoidectomy for Small Superior-Projecting Paraclinoid Aneurysms: Visual and Angiographic Outcome Evaluation.

INTRODUCTION: Optic foraminotomy (OF) has been recently proposed as an alternative to anterior clinoidectomy (AC) for selected types of paraclinoid aneurysms. In this study, OF and AC were compared for small superior-projecting paraclinoid aneurysms assuming visual and angiographic results as outcome measures. Indications for OF are also discussed. METHODS: Data of patients who underwent surgery for a paraclinoid aneurysm in the last 10 years were collected across 3 tertiary hospitals. Small to regular-size and superior projecting aneurysms were sorted. Multiple and complex aneurysms were excluded. Records of patients who went through OF were compared with those of patients who underwent AC. Neurologic outcome was reported as a modified Rankin Scale. Aneurysm complete occlusion rate and rate of approach-related worsened vision were selected as outcome measures of efficacy and safety, respectively, of the OF versus AC. Unpaired t test and χ2 test were used for numerical and categorical variables, respectively. A P value less than 0.05 was considered statistically significant. RESULTS: OF and AC groups involved 18 and 25 patients, respectively. Complication rate, overall neurologic outcome, rate of approach-related worsened vision, and complete occlusion rate did not differ between the groups. The average follow-up was 51 ± 34 and 60 ± 41 months in the OF and AC groups, respectively. CONCLUSIONS: Compared to AC, OF did not show either a higher rate of approach-related worsened vision or a lower aneurysm complete occlusion rate. OF can be considered a valid alternative to the AC for small superior-projecting dorsal ICA wall paraclinoid aneurysms.

Pituitary Stalk Hemangioblastoma: Complete Resection through Orbitozygomatic Approach with Extradural Anterior Clinoidectomy.

Background Pituitary stalk hemangioblastomas (PSHBLs) are rare vascular tumors and their surgical removal is challenging due to the proximity with several fundamental anatomic structures including the pituitary stalk, third ventricle, hypothalamus, and optic pathways. To date, only few descriptions of transcranial and transsphenoidal approaches for PSHBLs have been reported in the literature and none in video, with suboptimal outcomes in terms of pituitary function preservation. Here, we describe the use of orbitozygomatic (OZ) craniotomy with extradural anterior clinoidectomy (EAC) for the removal of a PSHBL with preservation of the pituitary stalk. Case Description A 60-year-old woman with a sporadic symptomatic HBL of the pituitary stalk, with the typical features of avid contrast enhancement on T1- and flow voids on T2-weighted magnetic resonance imaging (MRI) images, underwent a right OZ craniotomy with EAC. The choice of the approach was guided by the necessity of exposing the floor of the 3rd ventricle and infundibulum, where the origin of the pituitary stalk is better appreciated and preserved, without brain retraction. EAC was deemed important due to the necessity of widening the right carotico-oculomotor and opticocarotid triangles and gaining access to the ophthalmic segment of the internal carotid artery, origin of the superior hypophyseal artery, and the tumor supply. The postoperative MRI confirmed gross tumor removal with preservation of the pituitary stalk and no tumor recurrence after 2 years of follow-up. Conclusion OZ craniotomy coupled with EAC facilitates surgical removal of PSHBLs thus augmenting the chances of pituitary function preservation. The link to the video can be found at https://youtu.be/hH65W937RGY .

Endoscopic transorbital extradural anterior clinoidectomy: A stepwise surgical technique and case series study [SevEN-013].

Background: Anterior clinoidectomy is an important procedure for approaching the central skull base lesions. However, anterior clinoidectomy through the endoscopic transorbital approach (ETOA) still has limitations due to technical difficulties and the structural complexity of the anterior clinoid process (ACP). Therefore, the authors designed a stepwise surgical technique of extradural anterior clinoidectomy through the ETOA. The purpose of this study was to evaluate the feasibility of this technique. Methods: Anatomical dissections were performed in 6 cadaveric specimens using a neuroendoscope and neuro-navigation system. The extradural anterior clinoidectomy through the ETOA was performed stepwise, and based on the results, this surgical technique was performed in the 7 clinical cases to evaluate its safety and efficiency. Results: Endoscopic extradural anterior clinoidectomy was successfully performed in all cadaveric specimens and patients using the proposed technique. This 5-step technique enabled detachment of the lesser wing of sphenoid bone from the ACP, safe unroofing of the optic canal, and resection of the optic strut without injuring the optic nerve and internal carotid artery. Since the sequential resection of the 3 supporting roots of the ACP was accomplished safely, anterior clinoidectomy was then successfully performed in all clinical cases. Furthermore, no complications related to the anterior clinoidectomy occurred in any clinical case. Conclusion: We designed a stepwise surgical technique that allows safe and efficient anterior clinoidectomy through the ETOA. Using this technique, extradural anterior clinoidectomy can be accomplished under direct endoscopic visualization with low morbidity. Since this technique is applicable to the central skull base surgery where anterior clinoidectomy is necessary, it expands the application of the ETOA.

Clip Reconstruction of a Previously Leaked Large Complex Posterior Communicating Segment Aneurysm with Extradural Anterior Clinoidectomy.

Fusiform or near-fusiform aneurysms that involve the long segment of the supraclinoid internal carotid artery (ICA) pose significant challenges to neurovascular surgeons. Involvement of the origin of vital branching arteries in this segment may preclude safe treatment with flow diverting stents. In addition, clip reconstruction may also not be possible in this region due to entire or near-entire involvement of the circumference of the ICA ( Fig. 1 ). In this video article, we present a case of a complex and previously leaked, (visualized with hemosiderin) aneurysm of the posterior communicating segment of the ICA, in a 60-year-old female. Multiple complexities made this aneurysm challenging to treat. These included (1) a 270-degree encirclement of the ICA with multiple lobulations that left only a small section of nondiseased vessel wall, (2) a relatively short segment of the supraclinoidal ICA that made proximal control challenging thus requiring an extradural anterior clinoidectomy, (3) a fetal posterior communicating artery that originated immediately proximal to the beginning of the aneurysm, and lastly, (4) an anterior choroidal artery that was firmly adherent over the aneurysm dome. In this video, we present the microsurgical steps for dealing with this complex aneurysm, including extradural clinoidectomy and clip reconstruction ( Fig. 2 ). Postoperatively, the patient woke up without any deficits. Angiography showed complete obliteration of the aneurysm. The link to the video can be found at: https://youtu.be/3Zz-ecvlDIc .

Cavernous Sinus Epidermoid Cyst Removal through a No-Keyhole Pterional Craniotomy: Operative Video and Technical Nuances.

Intracranial epidermoid cysts are considered benign tumors with good general prognosis. However, their radical removal may be associated with certain morbidity, especially when the capsule is attached to neurovascular structures. Epidermoid cysts located in the cavernous sinus are very rare. We present an operative video of a 22-year-old female patient, who suffered a right-sided headache for 5 years. The video demonstrates main steps and surgical nuances of resection of a right interdural cavernous sinus epidermoid cyst, measuring 22 × 19 × 21 mm (4.3 cc) ( Fig. 1A ). On initial physical examination, the patient had a right partial third nerve palsy (mild ptosis with minimal diplopia), without any other cranial nerve deficit. A right no-keyhole pterional craniotomy was performed, followed by extradural anterior clinoidectomy and peeling of the outer dural layer of the lateral wall of the cavernous sinus. The dura matter was also detached from the distal carotid dural ring, which was exposed by the clinoidectomy ( Fig. 2A ). This maneuver provided excellent exposure of the interdural epidermoid cyst, which severely compressed the oculomotor nerve against the posterior petroclinoid dural fold ( Fig. 2B ). Gross total resection of the epidermoid cyst was achieved ( Fig. 1B and C ). The patient developed a transient worsening of the third nerve palsy, which recovered completely 3 months after the surgery. Postoperative magnetic resonance imaging revealed no signs of residual tumor. The link to the video can be found at: https://youtu.be/pobhYb5ZNig .