Lateral Supraorbital Research Articles

Comparative anatomical analysis between lateral supraorbital and minipterional approaches.

The pterional craniotomy, described by Yasargil and Fox in 1975, constitutes the most traditional and important surgical access in vascular neurosurgery. Minimally invasive alternatives include the minipterional (MP) and lateral supraorbital (LSO) craniotomies, which avoid complications such as injury to the frontal branch of the facial nerve, temporal muscle dysfunction, depression of the craniotomy site, frontal sinus opening, and cosmetically unacceptable outcomes. We evaluated and compared the exposures provided by MP and LSO craniotomies through quantitative measurements of the surgical exposure area around the circle of Willis and parasellar regions, as well as angular and linear exposures of the internal carotid artery (ICA) bifurcation, middle cerebral artery (MCA), midpoint of the anterior communicating artery, and tip of the basilar artery (BA). Seven fresh cadavers were dissected at the São Paulo Medical Examiner's Office, SP, and three at the skull base laboratory of Weill Cornell Medical College, New York, USA. The craniotomies were performed sequentially, initially with the LSO craniotomy followed by the MP. After the craniotomy, the surgical exposure area, craniotomy area, and angular exposures in the horizontal and vertical axes were determined. The MP craniotomy provided better angular exposure for the ipsilateral MCA, while the LSO craniotomy and BA provided better vertical axis exposures. The LSO craniotomy provided better angular exposure in the vertical axis for the midpoint of the anterior communicating artery and contralateral ICA bifurcation. Regarding surgical exposure and craniotomy area, there were no statistically significant differences. The MP craniotomy offers a significantly larger surgical exposure compared to the LSO craniotomy, with specific advantages regarding angular exposure to important neurovascular structures. This study provides important quantitative data to guide the choice between these minimally invasive access techniques in vascular neurosurgery.

Comparative cost analysis of endovascular and open approaches for elective treatment of middle cerebral artery aneurysms

Background Intracranial aneurysms of the middle cerebral artery can be treated using several open surgical and endovascular approaches. Given the growing evidence of clinical equipoise between these various treatment strategies, there is a need to assess the costs associated with each. Methods Cost of aneurysm treatment was divided into two categories for comparison. “Initial cost” comprised the total in-hospital expenses for initial aneurysm treatment and “total cost” comprised initial aneurysm treatment and all expenses relating to readmission due to treatment-related complications, prescribed catheter angiograms for monitoring of treatment stability, and any retreatments needed for a given aneurysm. The open surgical group was subdivided into a pterional approach group and a lateral supraorbital (LSO) approach group for. Results Median initial cost was $37,152 (IQR $31,318–$44,947) for aneurysms treated with the pterional approach, $29,452 (IQR $27,779–$32,826) for aneurysms treated with the LSO approach, and $19,587 (IQR $14,125–$30,521) for aneurysms treated with endovascular approaches. The median total cost was $39,737 (IQR $33,891–$62,259) for aneurysms treated with the pterional approach, $31,785 (IQR $29,513–$41,099) for aneurysms treated with the LSO approach, and $24,578 (IQR $18,977–$34,547) for aneurysms treated with endovascular approaches. Analysis of variance test demonstrated variance across groups for both initial and total cost ( p = 0.004, p = 0.008, respectively). In our subsequent analysis, initial cost and total cost were higher in the pterional group than the endovascular group ( p = 0.003 and p = 0.006, respectively). Conclusions Endovascular treatment of elective aneurysms has a significantly lower cost than open surgical treatment with the pterional approach, but not with the LSO approach. For aneurysms not amenable to endovascular treatment, a minimally invasive LSO approach carries a lower cost burden than a pterional approach.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Lateral Supraorbital Approach with Expanded Indications

Abstract Objectives The lateral supraorbital (LSO) approach is a less-invasive alternative to the pterional craniotomy that provides rapid transsylvian access. Establishing familiarity with the LSO technique and its features as compared with other anterolateral approaches is an important component of advanced skull base training. We present a step-by-step demonstration of the LSO approach using cadaveric dissection in a manner that is digestible for trainees at various levels. Design This is anatomic step-by-step dissection and representative case series. Setting This study was carried out in the cadaveric dissection laboratory. Participants A formalin-fixed, latex-injected cadaveric head specimen was dissected under microscopic magnification by a neurosurgery resident under faculty supervision. Following dissection, representative case applications were reviewed. Main Outcome Measures Dissection and case illustration were the main outcome measures. Results A single-layer myocutaneous flap is developed, and a single-burr-hole technique is used, followed by extensive drilling of the sphenoid wing. The dura is opened in a C-shaped fashion centered on the Sylvian fissure, exposing the inferior frontal and superior temporal lobes. Labeled photographs of dissections with pertinent anatomical structures are presented. Three case examples illustrating the versatility of the LSO approach, including the resection of a large pituitary adenoma, an inferior frontal melanoma metastasis presenting to the Sylvian surface, and a frontoinsular low-grade glioma, are reviewed. Conclusions As compared with the pterional craniotomy, the LSO approach involves a shorter incision, smaller craniotomy, and faster exposure; it can be conveniently tailored to various indications. Understanding the step-by-step dissection and indications of the LSO approach is of paramount importance to neurosurgery trainees.

Application of protective superficial temporal artery to middle cerebral artery bypass through the lateral supraorbital approach: Technical note

ObjectiveThe lateral supraorbital (LSO) approach is a minimally invasive craniotomy widely used in the surgical treatment of intracranial aneurysms (IAs). A protective bypass is considered a safety measure in high-risk and complex clipping procedures to maintain distal cerebral flow. However, the protective bypass has so far only been applied through a pterional or larger craniotomy. We aimed to describe the characteristics of the superficial temporal artery to middle cerebral artery (STA-MCA) bypass through the LSO craniotomy to treat complex IAs. MethodsWe retrospectively identified six patients with complex IAs who underwent clipping and a protective STA-MCA bypass through the LSO approach between January 2016 and December 2020. The STA donor artery was harvested through the same curvilinear skin incision with a small extension, and it was anastomosed to the opercular segment of the MCA. Subsequently, aneurysm clipping followed standardized steps. ResultsAnastomosis was successful in all patients. Despite requiring temporary occlusion of the parent artery, all aneurysms were successfully clipped without any neurological deterioration. ConclusionsA protective STA-MCA bypass is feasible through the LSO approach with certain technical modifications. This technique helps protect distal cerebral flow for safe clip placement in the treatment of complex IAs with the associated benefits of a less invasive craniotomy.

Minimally invasive craniotomies for lesions of the anterior and middle fossa.

Minimally invasive craniotomies are the subject of increasing attention over the last two decades in neurosurgery, following the current trend of attempting to increase patient safety by providing surgeries with less tissue disruption, blood loss, and decreased operative time. However, a significant information overlap exists among the various keyhole approaches regarding their indications and differences with more invasive techniques. Therefore, the present study aims to comprehensively review, illustrate, and describe the potential benefits and disadvantages of minimally invasive techniques to access the anterior and middle fossa, including the mini-pterional, mini orbito-zygomatic, supraorbital, lateral supraorbital, and extended lateral supraorbital approaches while comparing them to classic, more invasive approaches.

The Lateral Supraorbital Craniotomy Approach for Anterior Circulation Aneurysms: A Modern Surgical Case Series in the Endovascular Era

The lateral supraorbital (LSO) approach is a minimally invasive modification of the standard pterional approach to anterior circulation aneurysms. This study aimed to describe a dual-trained cerebrovascular neurosurgeon's first 18-month experience with the LSO approach, including decision-making criteria and lessons learned. This retrospective case series analyzed 50 consecutive patients treated with LSO craniotomy for aneurysm clipping by a single surgeon. Aneurysms were separated into 3 categories by location: internal carotid artery, anterior communicating artery, and middle cerebral artery. Surgical characteristics were evaluated for differences by location and rupture status. Aneurysm clipping via LSO was performed on 57 aneurysms in 50 patients. Fixed retraction was employed less often in patients with internal carotid artery aneurysms than in patients with anterior communicating artery, middle cerebral artery, or multiple aneurysms (10% vs. 68.2%, 45.5%, and 42.9, P= 0.02). Of patients, 26 (52%) presented with subarachnoid hemorrhage; the majority of patients (92.3%) had Hunt and Hess grade I-III. No differences were noted in intraoperative rupture rates, fixed retractor use, operative duration, or estimated blood loss by rupture status. Adverse events included permanent frontalis nerve palsy in 1 patient (2%), temporalis atrophy in 1 patient, and transient aphasia in 1 patient. No postoperative hematomas or strokes were observed. The LSO approach can safely and effectively treat anterior circulation aneurysms and should be considered a viable minimally invasive option for aneurysm clipping. Further studies comparing the LSO approach with other cranial approaches are needed.

Determination of Current Flow Induced by Transcutaneous Electrical Nerve Stimulation for the Treatment of Migraine: Potential for Optimization.

Introduction: Transcutaneous electrical nerve stimulation (TENS) for migraine involves the application of pulsatile stimulation through electrodes placed on the forehead to target the underlying trigeminal nerves. It is a simple, safe modality and has secured clinical approval in several markets including the European Union and the United States. Despite nearing almost 7 years of use (postclinical approval), the exact mechanism of action is not fully known. Guided by the need to stimulate the trigeminal nerves bilaterally, electrode dimensions are simply required to extend enough to cover the underlying nerves. The goal of this study is to examine induced current flow [magnitude and spatial distribution of electric field (EF)] and another driver of stimulation [activating function (AF)] due to TENS therapy for migraine for the first time. We further consider the effect of changing the electrode dimension and shape and propose a design modification to deliver optimal flow.Methods: We developed the first ultra-high-resolution finite element (FE) model of TENS for migraine incorporating the target supratrochlear (ST) and the supraorbital (SO) nerves. We first simulated the clinically approved V-shaped geometry. We then considered three additional designs: extended V-shaped, idealized pill-shaped, and finally an extended V-shaped but with greater contact spacing (extended V-shaped +CS).Results: Our findings revealed that the clinically approved electrode design delivered substantially higher mean current flow to the ST nerve in comparison with the SO nerves (Medial: 53% and Lateral: 194%). Consideration of an extended design (~10 mm longer and ~ 4 mm shorter) and a pill-like design had negligible impact on the induced current flow pattern. The extended V-shaped +CS montage delivered relatively comparable current flow to each of the three target nerves. The EF induced in the ST nerve was 49 and 141% higher in the Medial and Lateral SO nerve, respectively. When considering maximum induced values, the delivery of comparable stimulation was further apparent. Given the existing electrode design's established efficacy, our results imply that preferential targeting of the ST nerve is related to the mechanism of action. Additionally, if comparable targeting of all three nerves continues to hold promise, the extended V-shaped +CS montage presents an optimized configuration to explore in clinical studies.

Influencing Factors for Complication with Aneurysm Rupture of the Fetal Posterior Communicating Artery After Clipping Through the Lateral Supraorbital Approach and Prognosis

BackgroundTo explore the influencing factors for complication with aneurysm rupture of the fetal posterior communicating artery after clipping through the lateral supraorbital (LSO) approach and prognosis.MethodsA total of 119 patients with posterior communicating artery aneurysm (PCoAA) accompanied by fetal posterior cerebral artery (fPCA), who underwent clipping through the LSO approach from January 2014 to December 2019, were selected. They were aged 50–70 years old, (60.5 ± 13.7) on average. The treatment outcome, incidence of complications and follow-up results were analyzed. Based on the follow-up results, univariate comparative analysis was conducted for the clinical data of patients with good or poor prognosis. The statistically significant factors were incorporated into multivariate Cox regression analysis, and the nomogram prediction model for prognosis was established. The accuracy of the model was assessed using the Hosmer–Lemeshow goodness-of-fit test.ResultsClipping through the LSO approach was successful in all cases. Perioperative complications occurred in 41 patients. According to the follow-up results, 89 patients had good prognosis, while 30 had poor prognosis. Age of > 65 years old, history of hypertension, high Hunt–Hess grade and high modified Fisher grade were independent risk factors for the poor prognosis of patients with PCoAA accompanied by fPCA after clipping through the LSO approach. The results obtained by the established model were consistent with the actual ones.ConclusionAge, history of hypertension, Hunt–Hess grade and modified Fisher grade are independent risk factors for the prognosis of patients with PCoAA accompanied by fPCA after clipping through the LSO approach.

Transcranial Approaches to the Orbit.

Transcranial approaches to the orbit provide familiar and flexible approaches with wide access to the majority of the orbit, only limited in the inferomedial orbit. A pterional craniotomy is the predominant approach but can be expanded with an orbital or zygomatic osteotomy for even wider access. Minimally invasive approaches, such as the lateral supraorbital or "eyebrow" supraorbital approach, are options for selected pathologies and minimize morbidity related to the approach.

Anatomical Assessment of the Endoscopic Assisted Lateral Supraorbital Approach and Endoscopic Endonasal Transclival Approach to Basilar Apex Aneurysms.

To assess the feasibility of using an endoscopic-assisted lateral supraorbital (LSO) approach and an endoscopic endonasal transclival approach (EETA) for basilar apex (BAX) aneurysms. Ten cases with LSO approaches, with or without posterior clinoidectomy and endoscopic assistance, and 10 cases with EETA, with or without drilling of the dorsum sellae, were performed on 20 cadaveric heads. Anatomical exposure and surgical freedom at the BAX were evaluated. Anatomical exposure provided by the LSO approach was limited to the BAX and ipsilateral posterior cerebral artery (PCA) and increased with a mean value of 5.0 mm after posterior clinoidectomy; the basilar artery, contralateral PCA, and superior cerebellar arteries (SCAs) were visualized in all cases. Accordingly, surgical freedom was larger. Endoscopic assistance provided a significant increase in basilar artery exposure; however, surgical freedom did not increase markedly. The main advantage of EETA was the greatest exposure of the basilar artery. With drilling of the dorsum sellae, anatomical exposure increased by a mean value of 3.4 mm, and provided the greatest amount of surgical freedom and visualization of the basilar artery terminal bifurcation and of the SCAs in all cases. The endoscopic-assisted LSO approach and the EETA may represent a feasible approach for treatment of BAX aneurysms lying within 5.0 mm below and within 3.4 mm above the dorsum sellae.

Surgical resection of tuberculum sellae meningiomas through lateral supraorbital approach: A report of 34 cases

Objective To assess the reliability and safety of lateral supraorbital (LSO) approach in the surgical treatment of tuberculum sellae meningiomas (TSMs). Methods A total of 34 patients underwent operation through LSO approach between June 2013 and June 2017 at Department of Neurosurgery at Qilu Hospital of Shandong University and their clinical data were retrospectively analyzed in this study. All patients underwent surgical resection of the tumor via LSO approach. The extent of resection of the tumor was assessed using the Simpson classification. The effectiveness of the procedure was evaluated based on the patient's postoperative MRI and improvement in neurological symptoms, and the safety of the procedure was assessed based on the occurrence of postoperative complications. Results All patients were followed up for 3-36 months with an average of 12±5 months. Of the 34 patients, 30 underwent Simpson Ⅰ-Ⅱ resection and 4 received Simpson Ⅲ resection. Postoperative visual acuity was improved in 23 cases, no change was reported in 8 cases, and visual impairment was worse than preoperative conditions in 3 cases. There were 3 cases of postoperative fever, 3 cases of hyponatremia, 1 case of psychiatric symptoms, 1 case of cerebral edema, and 2 cases of epileptic seizures. In 1 (3%) patient, postoperative imaging findings confirmed recurrence. Conclusions LSO approach has multiple advantages including simplified and fast skull opening and closing, clean operative field and small trauma, and it could be used in the effective treatment of TSMs. Key words: Meningioma; Microsurgery; Treatment outcome; Lateral supraorbital approach; Tuberculum sellae

Selection Strategy for Optimal Keyhole Approaches for Middle Cerebral Artery Aneurysms: Lateral Supraorbital Versus Minipterional Craniotomy

The lateral supraorbital (LS) and minipterional (MP) approaches have been reported for treating intracranial aneurysms as alternative to the pterional approach. We describe our decision making for selecting the minicraniotomy, LS versus MP, for managing noncomplex aneurysms of the middle cerebral artery (MCA), based on the depth of the aneurysm within the Sylvian fissure. We report on a consecutive case series of 50 patients who underwent clipping of 54 ruptured/unruptured MCA aneurysms by means of LS or MP craniotomies. The distance between the MCA (M1) origin and the aneurysmal neck is key to selection of the approach: LS was used for MCA aneurysms <15 mm from the M1 origin and MP for MCA aneurysms ≥15 mm from the M1 origin. 11 of 50 patients presented with subarachnoid hemorrhage (10 ruptured MCA aneurysms). Overall, 59 aneurysms were successfully clipped (54 of the MCA). The mean distance between the M1 origin and the aneurysmal neck was 10.1 mm (range, 4-17 mm) for patients treated by LS and 20 mm (range, 15-30 mm) for those treated by MP. All but 1 MCA aneurysms were successfully treated. At last follow-up (mean, 14 months), no reperfusion of the clipped aneurysms was observed. Our strategy for selecting the keyhole approach based on the depth of the aneurysm within the Sylvian fissure is efficient and safe. We suggest the use of the LS approach when the aneurysm is <15 mm from the M1 origin and the MP approach when the aneurysm is ≥15 mm from the M1 origin.

Comparative analysis on microsurgical removal of craniopharyngioma via lateral supraorbital approach and standard pterional approach

BackgroundCraniopharyngioma is a kind of intracranial benign tumor that is primarily treated with surgery. At present, a variety of surgical approaches are used for tumor resection. We have conducted a comparative analysis of the two approaches most used in our department.MethodsThe study retrospectively analyzed the clinical data from 65 patients with craniopharyngioma surgically treated by the two approaches mentioned above. Among these patients, 24 were treated by lateral supraorbital (LSO) approach and 41 by standard pterional approach. Indicators including, but not limited to, length of incision, operation time, postoperative pituitary function, urine volume, visual function improvement, and hospitalization were used to compare these two groups of patients.ResultsThe data shows that there was no significant difference in total tumor resection rate (P = 0.54), postoperative visual field improvement (P = 0.68) and postoperative function of endocrine. However, the LSO approach significantly reduced the operative incision (P = 0.001), shortened the operation time (P = 0.001) and operative complexity, while reducing the incidence of postoperative complications (P = 0.04).ConclusionsIn surgical treatment of craniopharyngioma, LSO approach has similar surgical effect with standard pterional approach, but it can significantly shorten the operation time, reduce surgical trauma and the incidence of complications. Therefore, LSO provides another alternative to surgical approach for microsurgical removal of craniopharyngioma.

Lateral Supraorbital Versus Pterional Approach: Analysis of Surgical, Functional, and Patient-Oriented Outcomes

Recently, the lateral supraorbital (LSO) keyhole variant of the standard pterional (PT) approach has been popularized for anterior skull base surgery, because it provides good anatomic exposition, reduced complications, and better aesthetic and functional results. However, these aspects have been formally compared only by a limited number of studies. We reviewed our experience with 50 consecutive anterior communicating artery (AComA) and A1/A2 aneurysms. Of these 50 patients, 25 had undergone the standard PT approach and 25, the LSO variant. We report the results in terms of exclusion of the aneurysm, postoperative complications, functional/masticatory outcomes, and aesthetic and patient satisfaction. From January 2014 to December 2015, 25 patients with unruptured AComA and A1/A2 aneurysms underwent the standard PT craniotomy. From January 2016 to March 2017, another 25 patients underwent the LSO technique. No statistically significant differences were observed in the aneurysmal exclusion rate at angiographic follow-up or major complications. A statistically significant difference in the clinical outcome (Glasgow Outcome Scale) was evident only for the immediate postoperative time and was not significant during the follow-up period. The hospital stay was shorter in the LSO group. Minor complications, patient satisfaction, aesthetics, and functional and masticatory outcomes were significantly better statistically in the LSO group. The LSO approach demonstrated a lower rate of early clinical minor complications, with a reduction in hospitalization. The LSO approach provides better results for patient satisfaction, masticatory comfort, and cosmetic results. In our experience, the LSO approach is a safe and effective substitute to the standard PT craniotomy to treat unruptured AComA and A1/A2 aneurysms.

Comparison between modified lateral supraorbital approach and pterional approach in the surgical treatment of middle cerebral artery aneurysms

BackgroundThe Middle cerebral artery (MCA) aneurysm is a common type of craniocerebral aneurysm that is prone to rupture and high mortality. The classic surgical approaches are the Pterional approach and the Lateral Supraorbital (LSO) approach, but there are shortcomings.MethodsThis study retrospectively analyzed clinical and imaging data from 181 patients with MCA aneurysm clipping in the Department of Neurosurgery, First Affiliated Hospital of Soochow University between 2011 and 2017. Statistical analysis using parametric and nonparametric tests showed that P values below 0.05 were considered statistically significant.ResultsThe preoperative GCS score (P = 0.003), Hunt-Hess scale (P < 0.001) and the operating habits of the surgeon (P < 0.001) affected the surgeon to choose a surgical approach. The choice of two surgical methods on the operation time (P < 0.001), skin incision (P < 0.001), complications (P = 0.026), tracheotomy (P = 0.014), prognosis (P = 0.002) were significantly different. Different surgical approaches (P = 0.002), Hunt-Hess scale (P < 0.001), GCS scale (P < 0.001), GCS sorse (P < 0.001), skin incision (P = 0.031) and complications (P < 0.001) are closely related to the prognosis of patients.ConclusionsModified LSO approach provides another surgical approach for MCA aneurysm clipping, while avoiding the drawbacks of the LSO approach in the clipping of MCA distal aneurysm.

Lateral supraorbital approach for microsurgical resection of olfactory groove meningiomas

Objective To investigate the safety and efficacy of the application of lateral supraorbital (LSO) approach for microsurgical resection of olfactory groove meningiomas. Methods Between January 2013 and December 2016, 20 patients with olfactory groove meningiomas underwent surgery through LSO approach at Department of Neurosurgery, the Second Affiliated Hospital of Zhejiang University School of Medicine. Their clinical data, surgical treatment and outcomes were analyzed retrospectively. Neuroradiological findings, improvement of symptoms and some relevant evaluation scales were used to assess the efficacy and safety of LSO for resection of olfactory groove meningiomas. Results Six patients had Simpson grade Ⅰ resection, 12 had Simpson grade Ⅱ grade resection and 2 had Simpson grade Ⅳ resection. The mean operation time was 204.8±77.4 min and the mean intraoperative blood loss was 192.5±109.2 ml. Four patients developed fever post operation, 1 had psychiatric symptoms, 1 had disturbance of consciousness, 1 had cerebral edema, and 1 developed seizure. No incision infection or cerebrospinal fluid rhinorrhea occurred. Post surgery, 2 out of 8 patients with preoperative impairment of olfactory function obtained symptomatic improvement. Among the 4 patients with vision impairment, 2 achieved improvement, 1 remained the same and 1 reported aggravation. During the follow-up of 19 patients lasting 3-40 months with an average of 16.4±9.7 months, favorable outcomes were reported in 16 cases, severe disability in 1 and tumor recurrence in 2. There was no death. Conclusion Microsurgery through LSO approach demonstrates advantages in resection of olfactory groove meningiomas including shorter operative duration, less invasiveness, and low morbidity and mortality, which is thus worthy of recommendation. Key words: Meningioma; Microsurgery; Lateral supraorbital approach; Treatment outcome

Clinical analysis of lateral supraorbital microsurgical approach for ruptured anterior circulation aneurysm

Objective: To explore the safety and efficiency of lateral supraorbital (LSO) approach for the ruptured anterior circulation aneurysm. Methods: The clinical data of 23 patients with grade Ⅰ-Ⅲ ruptured anterior circulation aneurysm via LSO at the Second Hospital of Shandong University from February 2016 to December 2016 were retrospectively analyzed. The clinical data included their clinical manifestations, radiological finding, microsurgical techniques and follow-up results. Results: All patients were diagnosed as anterior circulation aneurysm by preoperative CT angiography (CTA) or Digital Subtraction Angiography (DSA). They all accepted aneurysm clipping via LSO. The operations carried out smoothly, with no operation related complications. They were followed up for 2 to 12 months, and the Glasgow outcome scales (GOS) were 5 in 18 patients (78.3%), 4 in 2 patients (8.7%), 3 in 2 patients (8.7%), and 1 in 1 patient (4.3%). Conclusion: LSO could provide adequate exposure for the anterior circulation aneurysm, so the clipping could be carried out safely and effectively. LSO is a simple and minimally invasive surgical approach, and when it is used by the skilled master of pterion approach, its advantage could be fully played.

Anterior Midline Skull Base Meningiomas: Interhemispheric Approach versus the Different Classical Surgical Approaches—Clinical Outcomes

Backgrounds: Different surgical approaches have been used to remove anterior skull base meningiomas (ASBMs) such as olfactory groove (OG) and tuberculum sellae (TS) meningiomas. These tumors are traditionally resected through pterional (PT), lateral supraorbital (LS) approaches. The endonasal endoscopic (EE) approach has gained some attention in recent years. The interhemispheric (IH) approach represents another option that has been rarely described and even more rarely compared with other approaches.

Quantification of Working Volumes, Exposure, and Target-Specific Maneuverability of the Pterional Craniotomy and Its Minimally Invasive Variants

Quantitative comparison of minimally invasive and standard cranial approaches remains a methodologic challenge. The aim of this study was to apply a new digital, navigation-based method to quantify multiple parameters of the pterional, supraorbital, lateral supraorbital and mini-pterional approaches and to describe a target-specific maneuverability score. Supraorbital, lateral supraorbital, mini-pterional, and standard pterional craniotomies were performed on 8 sides in 4 cadaver heads. The limits of superficial and deep exposure and surgical target points were registered with image-guidance (Medtronic Stealth). A custom software (Guided Therapeutics Eyes II Software [GTxEyesII]) calculated superficial and deep surface areas, working volumes, and target distances. Volumes were reconstructed digitally and visualized with GTxEyesII. Finally, we defined for each approach a target-specific maneuverability score based on surface exposure, target distance, target position, and anatomical obstacles. Surface exposure and volumes were significantly smaller for keyhole approaches compared with standard pterional craniotomy (P < 0.01). Maneuverability index scores showed the greatest values for standard pterional craniotomies, but nearly equally high scores could be achieved by one or several of the less-invasive approaches for most of the targets. The combination of a navigation-based measurement method with custom software (GTxEyesII) provides a powerful tool for visualization and quantification of surgical approaches. Compared with standard pterional craniotomy, alternative keyhole craniotomies offer comparable deep exposure with smaller working volumes and relatively high maneuverability for specific targets.

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.