Lateral supraorbital approach as an alternative to the classical pterional approach

Juha Hernesniemi: A message from overseas aspirants

Background

Juha Hernesniemi has played a pivotal role in advancing microneurosurgery, particularly in resource-limited settings where structured training opportunities are scarce. His philosophy of simplicity, efficiency, and anatomical preservation has influenced neurosurgeons worldwide, providing them with a framework to refine their skills despite technical and educational constraints.

Methods

This paper examines Hernesniemi's contributions to neurosurgical education through his extensive publications, surgical techniques, and mentorship philosophy. It highlights how his work has provided neurosurgical trainees with a structured pathway to mastering complex procedures, particularly in vascular and microneurosurgery.

Results

Hernesniemi's influence extends beyond direct mentorship, fostering a self-sustaining cycle of learning, where trainees who benefit from his work continue to pass on knowledge to future generations. His surgical videos, research papers, and simplified techniques have empowered neurosurgeons, especially those in resource-constrained environments, to perform complex procedures safely and effectively.

Conclusion

Juha Hernesniemi's contributions to microneurosurgery and neurosurgical education have left a lasting impact on the global community. His philosophy continues to shape future generations of neurosurgeons, reinforcing the power of knowledge dissemination in overcoming training barriers.

Microsurgical Clipping of Blood Blister-like Anterior Communicating Artery Aneurysm in a Patient with Total Occlusion of Left Internal Carotid Artery Aneurysm

Blister-like aneurysms represent a rare subtype characterized by a wide neck and dissecting appearance, predisposing them to perioperative rebleeding due to fragile walls. These aneurysms predominantly occur at non-branching sites of the internal carotid artery (ICA). Still, they may also manifest at atypical locations, including the anterior communicating artery (AComA), anterior cerebral artery, middle cerebral artery, posterior cerebral artery, and basilar artery.1 Treatment of blister-like aneurysms typically involves a combination of microsurgery and endovascular procedures, with no universally established optimal therapeutic approach. Because of the total occlusion of the left ICA and both cerebral hemispheres supply from the right ICA through the anterior communicating artery, we choose microsurgery to avoid thrombotic endovascular complications. Andaluz et al. presented a case series of 5 patients with blister AComA aneurysms who underwent microsurgical intervention.2 We present a challenging case of a 64-year-old man with thick subarachnoid hemorrhage and total and chronic thrombosis of the left ICA that came with a blister-like AComA aneurysm. This patient underwent microsurgical clipping of an aneurysm (Video 1). In our center, lateral supraorbital craniotomy, described by Hernesniemi et al.3 is the preferred surgical approach for most anterior circulation aneurysms. Under general anesthesia and in a supine position, the head was fixed using Sugita then the head and shoulder were elevated above to the cardiac level, rotated 30° to the contralateral side, and tilted slightly with some degree of flexion or extension depending on surgical preferences. A curvilinear frontotemporal skin incision behind the hairline was performed. Preserving facial nerve branches, a myocutaneous flap was reflected anteriorly to the superior orbital rim. One bur hole was set below the posterior extension of the superior temporal line and a modified 4 x 4 cm craniotomy was performed using a conventional craniotomy. The sphenoid ridge was drilled off using a diamond bur maximizing the surgical corridor. Dura was opened in a semilunar fashion and reflected anterolaterally. Dissection was started in the basal frontal surface and arachnoid dissection along the optic nerve and the optic-carotid triangle proceeded. We routinely dissected and opened the lamina terminalis posterior to optic chiasma for further cerebrospinal fluid drainage. Wide Sylvian fissure dissection was performed to minimize brain retraction. Sharp arachnoid dissection over the right A1 to AComA complex and optic chiasma was carried out and then proximal control is achieved with a temporary clip. During aneurysm surgery, an intraoperative rupture occurred that was controlled with a temporary clip. Sharp aneurysm dissection and then aneurysm clipping is made under the temporary clip. Six days after the operation, the patient was discharged home without any neurologic deficit.

Anatomoradiological comparison between the minipterional and supraorbital eyebrow approaches to the interpeduncular region

OBJECTIVE

Advances in surgical technology and microneurosurgery have led to increased utilization of so-called minimally invasive approaches, including the supraorbital eyebrow (SE) and minipterional (MPT) approaches for lesions involving the interpeduncular region. This study aimed to describe and compare anatomical landmarks, along with highlighting the advantages and disadvantages of the SE and MPT approaches to the interpeduncular region.

METHODS

Ten formalin-fixed, latex-injected cadaveric specimens were used to perform bilateral SE and MPT approaches to the interpeduncular region. The operative depth of each approach to key anatomical landmarks was measured. Forty-five axial thin-slice computed tomography studies were reviewed to calculate the operative angles, with consideration of the midline as a reference. A 3D interactive anatomical model generated through the photogrammetry scanning technique was described.

RESULTS

The depths of the operative corridors of the SE and MPT approaches to the interpeduncular fossa were 83.4 ± 1.8 mm and 67.7 ± 3.2 mm, respectively (p < 0.001). The mean angle of the MPT approach to the interpeduncular fossa was significantly wider than the one provided by the SE approach (39.9° ± 5.1° vs 28.4° ± 3.6°, p < 0.001). The interpeduncular region can consistently be accessed through the carotid-oculomotor triangle with the SE approach, as well as with the MPT approach. Furthermore, the SE route offered adequate access to the interpeduncular fossa through the opticocarotid triangle. The MPT route provided direct access to the upper prepontine cistern and anterior mesencephalic zone (AMZ).

CONCLUSIONS

The MPT approach provides a wider and shorter operative corridor and can be employed for lesions in the interpeduncular region with extension to the prepontine cistern and ventrolateral midbrain lesions requiring access through the AMZ. The SE approach is better suited for ventromedial midbrain lesions requiring access via the interpeduncular fossa safe entry zone. Additional studies analyzing these approaches in a clinical setting will help to delineate their reliability and efficacy.

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

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. Conclusion  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.

Keyhole Alternatives to Pterional Craniotomy for the Microsurgical Clipping of Anterior Circulation Aneurysms: Technical Pearls, Surgical Results, and a Case Selection Algorithm

BACKGROUND

Despite a recent surge in keyhole approaches to aneurysm clipping, only few studies have compared these approaches, and none have laid any foundation or roadmap for surgeons newly venturing into these procedures.

OBJECTIVES

To report a single surgeon's experience of multiple keyhole approaches to these aneurysms, and to highlight the case selection algorithm, technical nuances, and surgical results.

MATERIAL AND METHODS

Twenty-four patients (25 aneurysms) underwent aneurysm clipping using either a mini-pterional approach (MPA), lateral supraorbital approach (LSO), or a supraorbital keyhole approach (SOKHA). Intraoperative premature rupture, adequacy of clipping, and immediate postoperative and long-term functional outcomes were recorded.

RESULTS

All but five patients presented with ruptured aneurysms (Hunt and Hess grade 1 in 12 patients, grade 2 in 5 patients, and grade 3 in 2 patients). The anterior communicating artery (A-Comm; n = 14, 56%) was most frequently involved with aneurysms. The MPA was most frequently employed (n = 11, 45.8%), followed by the LSO (n = 9, 37.5%) and the SOKHA (n = 4, 16.7%). An intraoperative rupture (total n = 5, 20.8%) was most frequently seen in the SOKHA group (50%) and the only case of inadequate aneurysm clipping resulted from inadequate clipping ergonomics during the SOKHA for A-Comm aneurysm. Major complications occurred in the supraorbital approaches (one each in the LSO and SOKHA). Irrespective of the approach used, the long-term outcomes were excellent.

CONCLUSION

In properly selected patients, keyhole approaches-particularly the MPA and the LSO-can provide excellent surgical outcomes. The learning curve in the SOKHA is steeper. A pragmatic case selection algorithm is proposed.

Comparative anatomical analysis between lateral supraorbital and minipterional approaches

Background

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).

Methods

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.

Results

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.

Conclusion

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.

Surgical resection of petroclival meningiomas of the cerebellopontine angle and/or diaphragma sellae extension via an extended intradural anterior transpetrous approach

OBJECTIVE

This study aimed to describe the extended intradural anterior transpetrous approach (ATPA) and its usefulness for the surgical resection of petroclival meningiomas (PCMs) of the cerebellopontine angle (CPA) and/or diaphragma sellae (DS) extension.

METHODS

Between January 2017 and December 2019, a total of 22 patients with PCMs extending to the CPA/or DS underwent surgery via extended intradural ATPA by the senior author (Xr.X.). We retrospectively analysed the clinical data, radiological findings, surgical treatment, complications, and outcomes of patients and discussed the operative technique.

RESULTS

In 22 patients, the tumours were gross totally removed (Simpson I and II) in 18 patients (81.8%), subtotally (Simpson III) in 3 patients (13.6%), and partially (Simpson IV) in 1 patient (4.5%). One patient died 48 days after the operation, and no recurrence was found in 21 patients during a median follow-up of 26 months. Postoperative complications included in abducens nerve palsy in 12 patients with recovery in 10 patients, facial numbness in 4 patients with recovery in 3 patients, and hemiplegia and oculomotor nerve palsy in 1 patient each with recovery in all patients. The postoperative MRI showed temporal lobe oedema but no clinical symptoms in 3 patients.

CONCLUSION

Extended intradural ATPA is an alternative approach for PCMs of the CPA and/or DS extension. The single approach can expose both the sellar region and the posterolateral area of the IAC, which is advantageous for extended intradural ATPA.

Pterional vs. lateral supraorbital approach in the management of middle cerebral artery aneurysms: insights from a phantom model study

The pterional approach has traditionally been employed for managing middle cerebral artery (MCA) aneurysms. With potential benefits like reduced surgical morbidity and improved postoperative recovery, the lateral supraorbital approach (LSO) should be considered individually based on aneurysm morphology, location and patient-specific variations of the MCA anatomy, which requires considerable technical expertise traditionally acquired through years of experience. The goal of this study was the development and evaluation of a novel phantom simulator in the context of clinical decision-making in the managmement of MCA aneurysms. For this purpose, high-fidelity simulators inclusive of MCA models with identical M1- and bifurcation aneurysms were manufactured employing 3D reconstruction techniques, additive manufacturing and rheological testings. Medical students, neurosurgical residents, and seasoned neurosurgeons (n = 22) tested and evaluated both approaches. Participants' performances and progress over time were assessed based on objective metrics. The simulator received positive ratings in face and content validity, with mean scores of 4.9 out of 5, respectively. Objective evaluation demonstrated the model's efficacy as a practical training tool, particularly among inexperienced participants. While requiring more technical expertise, results of the comparative analysis suggest that the LSO approach can improve clipping precision and outcome particularly in patients with shorter than average M1-segments. In conclusion, the employed methodology allowed a direct comparison of the pterional and LSO approaches, revealing comparable success rates via the LSO approach while reducing operation time and complication rate. Future research should aim to establish simulators in the context of clinical decision making.

Pear-Shaped Craniopharyngioma: Selection of the Transcranial Approach With Respect to Topographical Classifications

We present the selection of the transcranial microsurgical approach, operative treatment, and outcomes following the resection of a pear-shaped craniopharyngioma (CP). A nine-year-old boy was operated on and followed up for 2.5 years after radical resection of the extrapial CP. Postoperatively, there was no tumor recurrence. The surgical strategy was discussed based on the preoperative MRI appearance of the CP, especially its morphological characteristics, including not only its size and shape but also its relationship with the hypothalamus, pituitary stalk/gland, ventricles, and optic chiasm, and the possible location of perforators. A description of the tumor topography is provided together with a discussion on the rationale for the selection of our surgical approach. Based on an understanding of the tumor topography, important information can be gained for approach selection, surgical planning, and anticipation of the hypothalamic-pituitary outcome.

Virtual reality guided focused Sylvian approach for clipping unruptured middle cerebral artery aneurysms

Objective

The increasing prevalence of unruptured intracranial aneurysms, detected through advanced brain imaging, necessitates a cautious approach to surgical intervention, with a focus on minimizing associated risks. This retrospective study explores the safety and better aesthetic outcomes of a Virtual Reality (VR) guided Focused Sylvian Approach (FSA) in comparison to the standard Pterional Surgical Approach (SPA) for the clipping of unruptured small-medium-size (<10 mm) Middle Cerebral Artery (MCA) aneurysms.

Methods

23 patients with 23 unruptured MCA aneurysms underwent the VR-guided FSA from June 2020 to September 2023, while 22 patients with 23 unruptured MCA aneurysms who underwent SPA were retrospectively recruited from the medical records database from January 2017 to May 2020. The comparative analysis involved surgical duration, postoperative complications, hospital stay, and a three-month follow-up patient's sequela survey.

Results

All aneurysms were effectively treated. The FSA procedure demonstrated a shorter surgical duration compared to the SPA group (164 ± 48 min vs. 196 ± 133 min, P = 0.2974). Despite a slightly higher median age in the FSA group (59 vs. 56 years), the median hospital stay was shorter in the FSA group (6 days) compared to the SPA group (7 days). The SPA group exhibited a higher incidence of complications (17/23) including cephalalgia, scar irritation, scar numbness, and temporal muscle dysfunction, compared to the FSA group (1/23), with a statistical significance of P < 0.05. Although FSA cannot demonstrate significant surgical efficiency in surgical duration and hospitalization, its superior aesthetics and preservation of temporalis muscle function compared to the SPA group.

Conclusion

The VR-guided FSA offers improved aesthetics and preservation of muscle function compared to the SPA. Our retrospective study underscores the potential benefits of VR-guided, personalized, focused Sylvian approaches for managing unruptured small-medium-size MCA aneurysms.

Anterior Choroidal Artery Aneurysm Clipping: Angiographic Diagnostics and Surgical Tactics Focused on Visualizing the Anterior Choroidal Artery Behind the Aneurysm

OBJECTIVE

This study describes our experiences with anterior choroidal artery (AChA) aneurysm clipping with a focus on visualizing the AChA just behind the aneurysm to identify the risk factors for adhesion of the AChA or its branches to the posterior wall of the AChA aneurysm.

METHODS

The initial segment of the AChA just behind the aneurysm was evaluated preoperatively using three-dimensional (3D) rotational angiography, and its course was designated as posteromedial, posterior, or posterolateral. The posterior aspect of the AChA aneurysm was inspected intraoperatively using an endoscope or micromirror.

RESULTS

Based on 3D rotational angiography, the main trunk of the AChA showed a posteromedial (n = 47, 57.3%), posterior (n = 18, 22.0%), or posterolateral (n = 17, 20.7%) course just behind the aneurysm. Intraoperatively, 14.6% (12 of 82) of the clipped AChA aneurysms revealed an AChA branch adhered to the posterior wall of the aneurysm. A multivariate analysis revealed that the posterior or posterolateral course of the initial segment of the AChA was a statistically significant risk factor for adhesion of an AChA branch to the posterior wall of the aneurysm (odds ratio [OR] 21.083, 95% confidence interval [CI] 2.567-173.166, P = 0.005).

CONCLUSIONS

The initial course of the AChA just behind an AChA aneurysm can be evaluated using 3D rotational angiography. In contrast to a posteromedial course, a posterior or posterolateral course of the AChA just behind an AChA aneurysm can be a significant risk factor for adhesion of an AChA branch to the posterior wall of an AChA aneurysm.

Minimally invasive keyhole supraorbital craniotomy as treatment option for penetrating foreign body through orbital roof

Intraorbital foreign body is a rare condition, especially when extending into the intracranial compartment. When facing this scenario in the ER, the neurosurgeon must carefully choose the optimal point of surgical access in order to reduce morbidity. The authors hereby report the case of a 66 year-old male with a penetrating trauma to the orbit reaching the anterior cranial base through the orbital roof and associated with an intracerebral hematoma. The removal of the foreign body was performed by a dual approach: an 'eyebrow' supraorbital keyhole craniotomy and an intra-orbital extra-ocular exploration, with later microsurgical drainage of the hematoma and evisceration of the eye 48 hours later. The patient developed a pseudomeningocele, which was treated with lumbar puncture and compressive dressing. After proper intravenous antibiotic prophylaxis, the patient was discharged 21 days after hospital admission.

Preservation of the middle meningeal artery during unruptured aneurysm surgery: an independent risk factor for postoperative chronic subdural hematoma

Background

Although microsurgical clipping for unruptured aneurysms has become safer and more efficient with modern neurosurgical advances, postoperative chronic subdural hematoma (CSDH) persists as an underrecognized complication. This study investigated the association between preservation of the anterior branch of the middle meningeal artery (MMA) during surgery and CSDH development.

Methods

We retrospectively reviewed 120 patients who underwent clipping for unruptured aneurysms at Kyungpook National University Chilgok Hospital between May 2020 and July 2023. We evaluated the patients on the basis of surgical approach-lateral supraorbital (LSO) or standard pterional craniotomy-and the status of the MMA postoperatively. We employed pre-and post-operative MR angiography to assess MMA preservation and used follow-up computed tomography scans to monitor CSDH development.

Results

Of the 120 patients, 22 (18.3%) developed CSDH. Univariate analysis revealed that male sex, advanced age, and MMA preservation are risk factors for postoperative CSDH. Multivariate analysis supported these findings, indicating a significant association with the development of CSDH. MMA preservation was reported in 65 patients, of whom 60 and 5 underwent LSO and pterional craniotomy, respectively.

Conclusion

Preservation of the anterior branch of the MMA during unruptured aneurysm surgery is a risk factor for postoperative CSDH development. Advanced age and male sex also contribute to the increased risk. These findings highlight the need for further investigation into surgical techniques that could mitigate postoperative CSDH development.

Clinical outcomes and complications of eyelid versus eyebrow approaches to supraorbital craniotomy: systematic review and indirect meta-analysis

OBJECTIVE

Eyebrow supraorbital craniotomy is a versatile keyhole technique for treating intracranial pathologies. The eyelid supraorbital approach, an alternative approach to an eyebrow supraorbital craniotomy, has not been widely adopted among most neurosurgeons. The purpose of this systematic review and meta-analysis was to perform a pooled analysis of the complications of eyebrow or eyelid approaches for the treatment of aneurysms, meningiomas, and orbital tumors.

METHODS

A systematic review of the literature in the PubMed, Embase, and Cochrane Review databases was conducted for identifying relevant literature using keywords such as "supraorbital," "eyelid," "eyebrow," "tumor," and "aneurysm." Eyebrow supraorbital craniotomies with or without orbitotomies and eyelid supraorbital craniotomies with orbitotomies for the treatment of orbital tumors, intracranial meningiomas, and aneurysms were selected. The primary outcomes were overall complications, cosmetic complications, and residual aneurysms and tumors. Secondary outcomes included five complication domains: orbital, wound-related, scalp or facial, neurological, and other complications.

RESULTS

One hundred three articles were included in the synthesis. The pooled numbers of patients in the eyebrow and eyelid groups were 4689 and 358, respectively. No differences were found in overall complications or cosmetic complications between the eyebrow and eyelid groups. The proportion of residuals in the eyelid group (11.21%, effect size [ES] 0.26, 95% CI 0.12-0.41) was significantly higher (p < 0.05) than that in the eyebrow group (6.17%, ES 0.10, 95% CI 0.08-0.13). A subgroup analysis demonstrated significantly higher incidences of orbital, wound-related, and scalp or facial complications in the eyelid group (p < 0.05), but higher other complications in the eyebrow group. Performing an orbitotomy substantially increased the complication risk.

CONCLUSIONS

This is the first meta-analysis that quantitatively compared complications of eyebrow versus eyelid approaches to supraorbital craniotomy. This study found similar overall complication rates but higher rates of selected complication domains in the eyelid group. The literature is limited by a high degree of variability in the reported outcomes.

Comparative analysis of supra-orbital keyhole approach and pterional approach for surgical clipping of intracranial anterior circulation aneurysms in patients with favorable Hunt and Hess grades

INTRODUCTION

Traditional large craniotomies have been the standard for aneurysm surgery. However, minimally invasive "keyhole" approaches have gained popularity for aneurysm clipping in recent years. This study focuses on Supra-Orbital Keyhole Approach (SOKHA),its use in clipping of aneurysms of the anterior Circle of Willis. Here we share the experiences of a tertiary care center regarding aneurysm clipping using SOKHA.

MATERIALS AND METHODS

We retrospectively reviewed 166 cases involving aneurysm clipping, with 62 patients undergoing SOKHA and 104 patients undergoing the pterional approach. Factors evaluated included patient demographics, aneurysm characteristics, incidence of intraoperative complications, temporary-clipping usage, and postoperative clinical outcomes. Glasgow Outcome Scale scores were utilized to assess clinical outcomes.

RESULTS

The study found that both the SOKHA and pterional approaches were similar in terms of age distribution, Hunt and Hess grades, and the incidence of hydrocephalus. The majority of aneurysms in both groups were anterior communicating artery aneurysms.Hydrocephalus was observed in 14.5 % of SOKHA cases and 13.5 % of pterional cases. Intraoperative aneurysm rupture occurred in 8.1 % of SOKHA cases and 7.7 % of pterional cases. There were no mortalities in the SOKHA group, while the pterional group had 1.92 % mortality rate. At the last follow-up, 77.4 % of SOKHA cases and 75.9 % of pterional cases had a favorable outcome (Glasgow Outcome Scale IV and V), with no significant difference.

CONCLUSION

SOKHA offers the advantage of potential cosmetic benefit with neurological outcomes comparable to those of the traditional pterional approach, in properly selected patients.

'What's in a name', a systematic review of the pterional craniotomy for aneurysm surgery and its many modifications with a proposal for simplified nomenclature

BACKGROUND

The pterional or frontosphenotemporal craniotomy has stood the test of time and continues to be a commonly used method of managing a variety of neurosurgical pathology. Already described in the beginning of the twentieth century and perfected by Yasargil in the 1970s, it has seen many modifications. These modifications have been a normal evolution for most neurosurgeons, tailoring the craniotomy to the patients' specific anatomy and pathology. Nonetheless, an abundance of variations have appeared in the literature.

METHODS

A search strategy was devised according to the 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. To identify articles investigating the variations in the pterional approach, the following search terms were applied: (pterional OR minipterional OR supraorbital) AND (approach OR craniotomy OR technique).

RESULTS

In total, 3552 articles were screened with 74 articles being read in full with 47 articles being included for review. Each article was examined according the name of the technique, temporalis dissection technique, craniotomy technique and approach.

CONCLUSION

This systematic review gives an overview of the different techniques and modifications to the pterional craniotomy since it was initially described. We advocate for the use of a more standardised nomenclature that focuses on the target zone to simplify the management approach to supratentorial aneurysms.

The Management of Intracranial Aneurysms: Current Trends and Future Directions

Intracranial aneurysms represent a major global health burden. Rupture of an intracranial aneurysm is a catastrophic event. Without access to treatment, the fatality rate is 50% in the first 30 days. Over the last three decades, treatment approaches for intracranial aneurysms have changed dramatically. There have been improvements in the medical management of aneurysmal subarachnoid haemorrhage, and there has been an evolution of treatment strategies. Endovascular therapy is now the mainstay of the treatment of ruptured intracranial aneurysms based on robust randomised controlled trial data. There is now an expansion of treatment indications for unruptured intracranial aneurysms to prevent rupture with both microsurgical clipping and endovascular treatment. Both microsurgical and endovascular treatment modalities have evolved, in particular with the introduction of innovative endovascular treatment options including flow diversion and intra-saccular flow disruption. These novel therapies allow clinicians to treat more complex and previously untreatable aneurysms. We aim to review the evolution of treatment strategies for intracranial aneurysms over time, and discuss emerging technologies that could further improve treatment safety and functional outcomes for patients with an intracranial aneurysm.

Rigid but nonmetallic cranioplasty after pterional craniotomy: Technical note

Background

Given the popularity of pterional craniotomy, numerous modifications have been made to prevent postoperative deformities. With the advent of titanium plates, fixation has become both simple and excellent. However, titanium plates can cause skin problems, infection, or cause skull growth to fail.

Methods

To develop a simple, cost-effective, and esthetically satisfactory fixation method, without the use of non-metallic materials, six young and older patients underwent pterional craniotomy. CranioFix Absorbable clamps were used to fix the bone flap in the frontal and temporal regions such that the frontal part was in close contact with the skull. After fixation, the bone chips and bone dust were placed in the bone gap and fixed with fibrin glue. We measured the computed tomography values of the reconstructed area and thickness of the temporal profiles postoperatively over time.

Results

Bone fusion was achieved in all patients by 1 year after surgery. Both the thickness of the temporalis muscle and the thickness of the temporal profile had changed within 2 mm as compared with the preoperative state.

Conclusion

Our simple craniotomy technique, gentle tissue handling, and osteoplastic cranioplasty yielded satisfactory esthetic results and rigidness in pterional craniotomy.

Supraorbital vs pterional keyhole for anterior circulation aneurysms: A systematic review and meta-analysis

Background

The supraorbital approach is a modification of the traditional pterional approach, and it offers the benefits of a shorter skin incision and a smaller craniotomy than the pterional approach. The purpose of this systemic review study was to compare the two surgical approaches for raptured and unruptured anterior cerebral circulation aneurysms.

Methods

We searched PubMed, EMBASE, Cochrane Library, SCOPUS, and MEDLINE, up to August 2021, for published studies on the supraorbital vs pterional keyhole approach for anterior cerebral circulation aneurysms, and reviewers performed a brief qualitative descriptive analysis of both approaches.

Results

Fourteen eligible studies were included in this systemic review. Results indicated that the supraorbital approach for anterior cerebral circulation aneurysms had fewer ischemic events compared to pterional approach. However, no significant difference between both groups in terms of complications such as intraoperative aneurysm rupture, brain hematoma, and postoperative infections for ruptured aneurysms.

Conclusion

The meta-analysis suggests that the supraorbital method for clipping anterior cerebral circulation aneurysms might be a viable alternative to the traditional pterional method as the supraorbital group had decreased ischemic events compared to the pterional group, however, the associated difficulties in utilizing this approach among ruptured aneurysms with cerebral oedema and midline shifts further needs to be understood.

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

OBJECTIVE

The 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.

METHODS

We 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.

RESULTS

Anastomosis was successful in all patients. Despite requiring temporary occlusion of the parent artery, all aneurysms were successfully clipped without any neurological deterioration.

CONCLUSIONS

A 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.

A meta-analysis of Lateral supraorbital vs mini Pterional approach in the outcome of rupture and unruptured noncomplex aneurysms' surgery

To determine the characteristics and to compare the functional outcomes and safety of different subfrontal approaches versus mini Pterional (MPT) approaches mainly for the treatment of ruptured noncomplex intracranial aneurysms. This meta-analysis included articles comparing outcomes of brain aneurysms (BAs) - most for the anterior circulation-, using Lateral supraorbital & Supraorbital keyhole (LSO) versus MPT approach. There were six articles left into the final article pool and the total number of patients was 683 (322 in LSO and 361 in the MPT group). In terms of the early and late time of surgery, the LSO seems to be superior over the MPT approach but with heterogeneity (OR -0.21, CI 95% -0.59 to 0.18, and p=0.04) or (OR -0.21, CI 95% -0.69 to 0.28, and p=0.05), and (p=0.02 and I²=68.97%) or (p=0.05 and I²=61.74%) respectively. Regarding the subgroup of patients with the supra-early time of surgery, surgical duration, completed occlusion, technical intraoperative complications, postoperative infection, intraoperative rupture, vasospasm, good and poor neurological outcomes and clinical deterioration, there was no superiority of the one method over the other. Mini or keyhole craniotomy even challenging might be a good option for neurosurgeons. Particularly in ruptured noncomplex aneurysms' surgery LSO seems to be superior over the MPT approach in terms of the early time and in the late time of surgery but with heterogeneity.

A Brief Explanation on Surgical Approaches for Treatment of Different Brain Tumors

The main goal of brain tumor surgery is to achieve gross total tumor resection without postoperative complications and permanent new deficits. However, when the lesion is located close or within eloquent brain areas, cranial nerves, and/or major brain vessels, it is imperative to balance the extent of resection with the risk of harming the patient, by following a so-called maximal safe resection philosophy. This view implies a shift from an approach-guided attitude, in which few standard surgical approaches are used to treat almost all intracranial tumors, to a pathology-guided one, with surgical approaches actually tailored to the specific tumor that has to be treated with specific dedicated pre- and intraoperative tools and techniques. In this chapter, the basic principles of the most commonly used neurosurgical approaches in brain tumors surgery are presented and discussed along with an overview on all available modern tools able to improve intraoperative visualization, extent of resection, and postoperative clinical outcome.

Implantation of Acellular Dermal Matrix to Prevent Frontotemporal Depression Following Minipterional Craniotomy for the Surgical Clipping of Unruptured Intracranial Aneurysms

OBJECTIVE

The objective of the study was to assess the esthetic efficacy of acellular dermal matrix (ADM) implantation to prevent frontotemporal depression (FTD) following minipterional craniotomy (MPT) to clip unruptured intracranial aneurysms.

METHODS

We retrospectively compared the incidence of FTD in 100 patients treated without ADM from March to July 2019 and 100 patients treated with ADM from August to December 2019. ADM was implanted in the interfascial layer to cover the temporalis muscle. The specific location and degree of FTD were analyzed by measuring the thickness and area of multiple points (P1-P12) and regions (S1-S3) through brain computed tomography preoperatively and 1 year postoperatively.

RESULTS

In the non-ADM group, the thickness at P1, P2, P5, P6, and P9 was reduced and the area of S1 and S2 was smaller after surgery than before surgery (P < 0.05), similar to the incision and suture site of the temporalis muscle. However, in the ADM group, the preoperative and postoperative measurements were not different. FTD recognition was significantly lower in the ADM group (6.0%) than that in the non-ADM group (17.0%) (P = 0.015) and occurred in the retroorbital region through P1, P2, P5, and P6, with the area under the receiver operating characteristic curves of 0.840, 0.766, 0.811, and 0.751, respectively. ADM implantation was the only significant predictive factor for FTD recognition in multivariate logistic regression analysis (odds ratio = 0.30; 95% confidence interval: 0.11-0.79; P = 0.015).

CONCLUSIONS

Even MPT cannot completely prevent FTD in the retroorbital region. ADM implantation in MPT can help to improve esthetic satisfaction.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Risk Factors for Postoperative Brain Contusion and Early Outcomes in Patients with Anterior Skull Base Meningiomas Undergoing Unifrontal Surgery: Single Center Experience with 110 Patients

Background

Though frontal lobe contusion is a major cause for morbidity and prolonged hospitalization following excision of anterior skull base meningiomas, there is only limited literature on this complication. This study aimed to find out the incidence of postoperative frontal lobe contusion, identify the risk factors for its development and its impact on early postoperative outcome.

Methods

Data from 110 patients who underwent excision of anterior skull base meningiomas through a unilateral supraorbital craniotomy from 2001 to 2018 were retrospectively analyzed. The risk factors analyzed for development of postoperative contusion were tumor location, size, volume, peritumoral edema, tumor consistency, extent of resection, tumor grade and type of retraction used.

Results

Simpson grade II excision was achieved in ninety-two patients (83.6%). There was no frontal lobe contusion in eighty-two patients (74.5%). Frontal lobe contusion was noted in twenty-eight patients (25.5%), but was severe in only four patients (3.6%). On multivariate analysis, fixed retractor use (OR 11.56 [1.21-110.03]; P =0.03) and WHO grade II tumor (OR 3.29 [1.11-9.77]; P =0.03) were independently associated with postoperative frontal lobe contusion. Patients with higher contusion grade had significantly longer postoperative hospitalization (P =.02) and lower KPS score at discharge (P =.01).

Conclusions

Unilateral supraorbital craniotomy and lateral subfrontal approach is an excellent procedure for excision of anterior skull base meningiomas with minimal postoperative complications related to frontal lobe retraction. Frontal lobe contusion should be avoided with the use of dynamic retraction, since postoperative contusion prolongs hospitalization and worsens the functional outcome at discharge.

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.

Microsurgical Management of Posterior Circulation Aneurysms: A Retrospective Study on Epidemiology, Outcomes, and Surgical Approaches

Posterior circulation aneurysms have been regarded as the most challenging for endovascular coiling and microsurgical occlusion. The role of microsurgical treatment is gradually being overlooked and diminishing in the trend of endovascular treatment. As microsurgical occlusion of posterior circulation aneurysms is decreasing, we present our relevant experience to evaluate treatment options and surgical approaches. A retrospective study was conducted in the Department of Neurosurgery of the First Affiliated Hospital of Soochow University between 2016 and 2021. Patients with posterior circulation aneurysms treated by clipping, bypass, and trapping were enrolled and followed up for at least six months. We included 50 patients carrying 53 posterior circulation aneurysms, 43 of whom had aneurysm ruptures. The posterior cerebral artery and posterior inferior cerebellar artery were the most common aneurysm locations. Direct clipping was performed in 43 patients, while bypass and trapping was performed in six patients. The retrosigmoid, far-lateral, and midline or paramedian suboccipital approaches were performed for those aneurysms in the middle and lower thirds. Aneurysms in the upper third required the lateral supraorbital approach, pterional approach, subtemporal approach, and occipital craniotomy. The lateral supraorbital approach was utilized in seven patients for aneurysms above the posterior clinoid process. Thirty-four patients recovered well with modified Rankin score 0–3 at discharge. No patient experienced aneurysm recurrence during the mean follow-up period of 3.57 years. Microsurgery clipping and bypass should be considered in conjunction with endovascular treatment as a treatment option in posterior circulation aneurysms. The lateral supraorbital approach is a feasible, safe, and simple surgical approach for aneurysms above the posterior clinoid process.

Effects of Modified Osteoplastic Pterional Craniotomy on Temporal Muscle Volume and Frontal Muscle Nerve Function

Introduction  Pterional craniotomy is a surgical approach frequently used in aneurysm and skull base surgery. Pterional craniotomy may lead to cosmetic and functional problems, such as eyebrow drop due to facial nerve frontal branch damage, temporal muscle atrophy, and temporomandibular joint pain. The aim was to compare the postoperative effects of our modified osteoplastic craniotomy with classical pterional craniotomy in terms of any change in volume of temporal muscle and in the degree of frontal muscle nerve damage. Materials and Methods  Aneurysm cases were operated with either modified osteoplastic pterional craniotomy or free bone flap pterional craniotomy according to the surgeon's preference. Outcomes were compared in terms of temporal muscle volume and frontal muscle nerve function 6 months postoperatively. Results  Preoperative temporal muscle volume in the modified osteoplastic pterional and free bone flap pterional craniotomy groups were not different ( p  > 0.05). However, significantly less atrophy was observed in the postoperative temporal muscle volume of the osteoplastic group compared with the classical craniotomy group ( p  < 0.001). In addition, when comparing frontal muscle nerve function there was less nerve damage in the modified osteoplastic pterional craniotomy group compared with the classical craniotomy group, although this did not reach significance ( p  > 0.05). Conclusion  Modified osteoplastic pterional craniotomy significantly reduced atrophy of temporal muscle and caused proportionally less frontal muscle nerve damage compared with pterional craniotomy, although this latter outcome was not significant. These findings suggest that osteoplastic craniotomy may be a more advantageous intervention in cosmetic and functional terms compared with classical pterional craniotomy.

Keyhole Approach for Clipping Anterior Circulation Aneurysms: Clinical Outcomes and Technical Note

Purpose: Keyhole craniotomy is a minimally invasive approach for the treatment of anterior circulation aneurysm. In this study, we evaluated the benefits and value of the keyhole approach by analyzing the surgical results in 235 patients with anterior circulation aneurysm treated by the keyhole approach and identifying lessons learned from addressing various complications in this approach.

Patients and Methods: This was a retrospective study in a single institution of 235 surgical patients with 248 anterior circulation aneurysms who had the supraorbital keyhole approach (SKA) or pterional keyhole approach (PKA) between January 2016 and January 2021. The modified Rankin Scale (mRS) was used to measure long-term results during follow up.

Results: All 235 patients' aneurysms were fully clamped and have not recurred. Among them, 31 (13.2%) had intraoperative aneurysm rupture, 8 (3.4%) had cerebral vascular spasm, and 4 (1.7%) had intraoperative brain edema. There were seven (3.0%) cases of postoperative infection, eight (3.4%) cases of postoperative cerebral infarction, one (0.4%) case of postoperative hematoma, and two (0.8%) patients had some form of cognitive impairment after surgery. Follow up after surgery demonstrated that 189 out of the 235 patients (80.4%) had favorable outcomes (mRS score 0–2), and 43 (18.3%) had poor outcomes (mRS from 3–5). There were three deaths (1.28%).

Conclusions: The keyhole approach has a quick postoperative recovery, a mild postoperative response, and a good surgical outcome. Our findings indicate that the keyhole approach is a safe and effective surgical method for the treatment of anterior circulation aneurysm.

Case Report: Internal Carotid Artery Thrombosis: A Rare Complication After Fibrin Glue Injection for Cavernous Sinus Hemostasis

Background: Fibrin glue injection within the cavernous sinus (CS) is a demonstrably safe and simple technique to control venous bleeding with a low complication rate. However, this technique does have inherent risks. We illustrate 2 cases of internal carotid artery (ICA) thrombosis after fibrin glue injection in the CS for hemostasis.

Methods: After encountering this complication recently, we conducted a retrospective review of the surgical database of 2 senior neurosurgeons who specialize in cerebrovascular and skull base surgery to identify patients with any complications associated with the use of fibrin glue injection for hemostasis. Approval was given by respective institutional review boards, and patient consent was obtained.

Results: Of more than 10,000 microsurgery procedures performed by 2 senior neurosurgeons with a combined experience of 40 years, including procedures for aneurysms and skull base tumors, 2 cases were identified involving ICA thrombosis after fibrin glue injection in the CS for hemostasis. Both cases involved severe ischemic complications as a result of the ICA thrombosis. In this article, we present their clinical presentation, characteristics, management, and outcomes.

Conclusion: Direct injection of fibrin glue into the CS for hemostasis can effectively control venous bleeding and facilitate complex dissections. However, it can be associated with ICA thrombosis, with subsequent serious ischemia and poor prognosis. Although this complication appears to be rare, increased awareness of this problem should temper the routine use of fibrin glue in anterior clinoidectomy and transcavernous approaches.

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

Background

To 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.

Methods

A 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.

Results

Clipping 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.

Conclusion

Age, 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.

Olfactory nerve sparing technique for anterior skull base meningiomas: how I do it

BACKGROUND

Olfactory function preservation is a desirable objective in anterior skull base (ASB) surgery. The "infracerebral-supraolfactory nerve" corridor is presented.

METHOD

The technique for preserving the olfactory nerves (OlfNs) in anterior ASB meningioma removal involves the following points: deep knowledge of the ASB vascular and meningeal anatomy, precise preoperative planning, wide and sharp dissection of the OlfNs away from the frontal lobes, gravity-aided frontal lobe retraction, Gelfoam-assisted hemostasis on nervous structures, and access to the lesion through an infracerebral-supraolfactory nerve corridor.

CONCLUSIONS

This technique may be a valid option for patients affected by anterior skull base meningiomas with intact preoperative olfactory function.

Minimally Invasive Subfrontal Approach: How to Make it Safe and Effective from the Olfactory Groove to the Mesial Temporal Lobe

BACKGROUND

 Different surgical approaches have been developed to manage lesions of the anterior and middle skull base areas. Frontal, pterional, bifrontal, and fronto-orbito-zygomatic approaches are traditionally used to reach these regions. With advancements in the neurosurgical field, skull opening should be simple and as minimally invasive as possible, tailored on the surgical corridor to the target. The supraorbital approach and the "keyhole" concept have been introduced and popularized by Axel Perneczky starting from 1998 and are now considered a part of everyday practice. The extended possibilities of this surgical route, considering the reachable targets and surgical limits, are described and systematically analyzed, including a description of the salient surgical anatomy, presenting different illustrative cases.

METHODS AND RESULTS

 Different illustrative cases are presented and discussed to underline the potentials and limits of the minimally invasive subfrontal approach (MISFA) and the possibilities to tailoring the craniotomy on the basis of the targets: extra-axial lesions with different localizations (anterior roof of the orbit, olfactory groove, tuberculum sellae, medial third of the sphenoid wing, anterior and posterior clinoid process), deeper intra-axial lesions (gyrus rectus, medial temporal lobe-uncus-amygdala-anterior hippocampus), and vascular lesions (anterior communicating aneurysm). Each case has been preoperatively planned considering the anatomical and radiologic features and using virtual simulation software to tailor the best possible corridor to reach the surgical target.

CONCLUSIONS

 The MISFA is a safe multicorridor approach that can be used efficiently to manage lesions of the anterior and middle skull base areas with extremely low approach-related morbidity.

Retrobulbar Hemangioblastomas in von Hippel-Lindau Disease: Clinical Course and Management

BACKGROUND

Retrobulbar hemangioblastomas involving the optic apparatus in patients with von Hippel-Lindau disease (VHL) are rare, with only 25 reported cases in the literature.

OBJECTIVE

To analyze the natural history of retrobulbar hemangioblastomas in a large cohort of VHL patients in order to define presentation, progression, and management.

METHODS

Clinical history and imaging of 250 patients with VHL in an ongoing natural history trial and 1774 patients in a neurosurgical protocol were reviewed. The clinical course, magnetic resonance images, treatment, and outcomes were reviewed for all included patients.

RESULTS

A total of 18 patients with retrobulbar hemangioblastoma on surveillance magnetic resonance imaging met the inclusion criteria for this study. Of the 17 for whom clinical information was available, 10 patients presented with symptoms related to the hemangioblastoma, and 7 were asymptomatic. The mean tumor volume was larger for symptomatic (810.6 ± 545.5 mm3) compared to asymptomatic patients (307.6 ± 245.5 mm3; P < .05). A total of 5 of the symptomatic patients were treated surgically and all experienced improvement in their symptoms. All 3 symptomatic patients that did not undergo intervention had continued symptom progression. Long-term serial imaging on asymptomatic patients showed that these tumors can remain radiographically stable and asymptomatic for extended periods of time (101.43 ± 71 mo).

CONCLUSION

This study suggests that retrobulbar hemangioblastomas may remain stable and clinically asymptomatic for long durations. Recent growth and larger tumor volume were associated with symptom occurrence. Surgical treatment of symptomatic retrobulbar hemangioblastomas can be safe and may reverse the associated symptoms.

Orbital Rim Sparing Single-piece Fronto-orbital Keyhole Craniotomy Through Eyebrow Incision: A Technical Report and Comparative Review

Background

The classical eyebrow supraorbital keyhole craniotomy has limited working volume due to the thick incurving of the frontal bone necessitating generous drilling of the frontal base. However, the basal variant with sectioning of the orbital rim results in increased periorbital edema.

Objective

We describe a novel orbital rim sparing single-piece fronto-orbital keyhole approach, probably the first such report with a comparative review of relevant literature.

Methods

Following eyebrow incision, bidirectional drilling with a ball tip behind the fronto-zygomatic suture exposes the periorbita and frontal dura, with orbital roof in-between. The craniotomy is fashioned with an angled fronto-orbital cut parallel to and sparing the orbital rim with dura-guard over the periorbita, a frontal cut over the dura, and an optional cut along the lateral orbital roof from within the burr hole. A comparative review of this technique with traditional methods is also carried out.

Results

Compared to the classical supraorbital keyhole, this minimally invasive approach yields a wider basal exposure with greater working volume for intracranial and orbital lesions. Compared to the basal variant of keyhole fronto-orbital approach, this technique results in the least disturbance to periorbita's attachment with the orbital margin, maintenance of orbital contour, better cosmesis with use of simple tools and self-fitting flap.

Conclusion

The orbital rim sparing single-piece fronto-orbital keyhole craniotomy is an easy and novel minimally invasive approach with greater working volume without the disadvantages of sectioning the orbital rim.

Microsurgical Management of the Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Feasibility Study

BACKGROUND

The proper head positioning decreases the surgical complications by enabling a better surgical maneuverability. Middle cerebral artery (MCA) bifurcation aneurysms have been classified by Dashti et al. [Surg Neurol. 2007 May;67(5):441-56] as the intertruncal, inferior, lateral, insular, and complex types based on dome projection. Our aim was to identify the optimum head positions and to explain the anatomic variables, which may affect the surgical strategy of MCA bifurcation aneurysms.

METHODS

The lateral supraorbital approach bilaterally was performed in the 4 cadaveric heads. All steps of the dissection were recorded using digital camera.

RESULTS

The distal Sylvian fissure (SF) dissection may be preferred for insular type and the proximal SF dissection may be preferred for all other types. Fifteen degrees head rotation was found as the most suitable position for the intertruncal, lateral type and subtype of complex aneurysms related with superior trunk. Thirty degrees head rotation was found the most suitable position for the inferior type, insular type, and subtype of complex aneurysms related with inferior trunk.

CONCLUSIONS

The head positioning in middle cerebral bifurcation aneurysms surgery is a critical step. It should be tailored according to the projection and its relationship with the parent vessels of the middle cerebral bifurcation.

Morphometric Comparison of the Pterional Trans-Sylvian and the Pretemporal Trans-Clinoidal Approaches to the Posterior Communicating Artery

BACKGROUND

Posterior communicating (Pcom) aneurysms in the modern era have tended toward increased complexity and technical difficulties. The pretemporal approach is a valuable extension to the pterional approach for basilar apex aneurysms, but its advantages for Pcom aneurysms have not been previously elucidated.

OBJECTIVE

To quantify characteristics of the pretemporal approach to the Pcom.

METHODS

We dissected 6 cadaveric heads (12 sides) with a pretemporal transclinoidal approach and measured the following variables: (1) exposed length of internal carotid artery (ICA) proximal to the Pcom artery; (2) exposed circumference of ICA at the origin of Pcom; (3) deep working area between the optic nerve and tentorium/oculomotor nerve; (4) superficial working area; (5) exposure depth; and (6) the frontotemporal (superior posterolateral) and (7) orbito-sphenoidal (inferior anterolateral) angles of exposure.

RESULTS

Compared with pterional craniotomy, the pretemporal transclinoidal approach increased the exposed length of the proximal ICA from 3.3 to 11.7 mm (P = .0001) and its circumference from 5.1 to 7.8 mm (P = .0003), allowing a 210° view of the ICA (vs 137.9°). The deep and superficial working areas also significantly widened from 53.7 to 92.4 mm2 (P = .0048) and 252.8 to 418.2 mm2 (P = .0001), respectively; the depth of the exposure was equivalent. The frontotemporal and spheno-Sylvian angles increased by 17° (P = .0006) and 10° (P = .0037), respectively.

CONCLUSION

The pretemporal approach can be useful for complex Pcom aneurysms by providing easier proximal control, wider working space, improved aneurysm visualization, and more versatile clipping angles. Enhanced exposure results in a potentially higher rate of complete aneurysm obliteration and complication avoidance.

The lateral supraorbital approach, doable and cosmetic access to anterior skull base

Background

The anterior skull base region can be reached through multiple corridors. The most frequently used are the pterional, bifrontal, unifrontal, and orbitozygomatic approaches. These approaches are more extensive and time consuming. The lateral supraorbital approach is a less extensive frontal modification of the classic pterional approach designed to manage tumors and aneurysms of this region.

Objective

To evaluate efficacy, safety, and cosmetic results of the lateral supraorbital approach and to present some tricks to have an easy access to different pathologies at the anterior skull base through this approach.

Methods

Analysis of 50 operations for anterior skull base pathologies, vascular and neoplastic, made through the lateral supraorbital approach in Neurosurgery Department, Tanta University Hospitals between January 2013 and April 2017. The basic steps in performing the procedure are described. Special tricks required in individual cases and how to identify their need from preoperative images are discussed.

Results

We operated on 50 patients having 34 neoplastic and 16 vascular lesions. The mean incision length was 11 cm, mean bone flap size was 3.5 × 5.4 cm, and mean craniotomy time was 20 min.

All patients were satisfied with their scars; there were no limitations to this approach regarding nature or size of the lesion. We had 8 morbidities (4 transient and 4 permanent) and 2 mortalities; all morbidities and mortalities were not related to the approach.

Conclusion

The lateral supraorbital approach is simple, fast, and effective corridor to anterior skull base pathologies without significant morbidities or mortalities related to the approach.

Supraorbital eyebrow keyhole approach for microsurgical management of ruptured anterior communicating artery aneurysm

The mortality and disability rate of patients with ruptured anterior communicating artery (AComA) aneurysm after bleeding is high. Even with the most advanced treatment methods, the incidence of complications remains high. The purpose of the present study was to determine the efficacy of microsurgery via supraorbital eyebrow keyhole approach (SOEK) in clipping ruptured AComA aneurysms. Between September 2010 and October 2018, 543 patients with intracranial aneurysms were admitted to the Department of Neurosurgery of the Third Affiliated Hospital of Sun Yat-Sen University (Guangzhou, China). Among them, 85 patients with ruptured AComA aneurysm and subarachnoid hemorrhage (SAH) underwent microsurgical clipping via the SOEK approach. In those patients, the clipping rate, complications and clinical efficacy of treatment were evaluated. The average age of the patients was 52.69±9.94 years (range, 28-78 years). The proportions of small, medium and large aneurysms were 83.5, 15.3 and 1.2%, respectively. Procedural complications occurred in 9 cases (10.5%). The occlusion rate of the aneurysms was 98.8%. The average follow-up period was 37.9 (±24.5) months. A total of 81.2% of the patients with SAH had a good clinical prognosisat 1 year (modified Rankin scale score, ≤2). In conclusion, for a skilled and experienced surgeon, SOEK was indicated to be a safe procedure for the treatment of ruptured AComA aneurysms; it provided sufficient intra-operative exposure and a high clipping rate.

Minipterional craniotomy for surgical clipping of anterior circulation aneurysms: compatibility between the feasibility, safety and efficiency

Objective

The aim of this study was to assess the feasibility, safety and efficiency of minipterional craniotomy (MPT) for surgical clipping of anterior circulation aneurysms.

Methods

A retrospective study was conducted to compare the MPT from Jan 2015 to Dec 2018 and conventional pterional craniotomy (CPT) from Jan 2012 to Dec 2013 in unruptured intracranial aneurysms (UIA) and ruptured intracranial aneurysms (RIA). The feasibility and safety of MPT and CPT were assessed by analyzing medical records, radiologic imaging, and clinical outcomes. The efficiency of MPT and CPT were based on a survey research of temporomandibular dysfunction, facial nerve paralysis, and facial asymmetry.

Results

Total 628 patients who underwent 458 MPT (UIA:313, RIA:145) and 170 CPT (UIA: 106, RIA: 64) with anterior circulation aneurysms were included in this study. The baseline characteristics between MPT and CPT had no difference (p>0.05). There was no difference in the incidence of postoperative hemorrhage or ischemic lesions between MPT and CPT (p>0.05). The incidence of surgical wound infection was lower in MPT (0.4%) than CPT (3.5%) (p=0.002). More than 90% of postoperative pain disappeared faster in MPT (14.25±4.83 days) than CPT (27.59±10.35 days), and the feeling of facial asymmetry in surgical side was also lower for MPT (1.7%) than CPT (7.6%) (p<0.001). In the MPT, no patients presented with progress to chronic pain, masticatory disability, discomfort of maximal mouth opening or permanent facial palsy.

Conclusions

We suggest that MPT and CPT had similar clinical outcomes, and MPT showed better functional and cosmetic outcomes than CPT in terms of temporomandibular dysfunction, facial nerve paralysis, and facial asymmetry. Therefore, MPT for surgical clipping of anterior circulation aneurysms can be a compatible technique that satisfies the feasibility, safety and efficiency.

The Transpalpebral Versus the Transciliary Variant of the Supraorbital Keyhole Approach: Anatomic Concepts for Aneurysm Surgery

BACKGROUND

The supraorbital craniotomy (SOC) is classically performed through a skin incision in the patient's eyebrow. A variant with a skin incision in the patient's eyelid has become increasingly popular in recent years.

OBJECTIVE

To compare the transpalpebral and the transciliary variants of the SOC with regard to their potential role in aneurysm surgery.

METHODS

We carried out cadaveric dissections and virtual craniotomies on computerized tomography datasets. The skin incision, the craniotomy location and size, the working angles, and the achievable exposure of neurovascular structures were assessed and compared for both variants of the SOC.

RESULTS

The skin incision measured 4 cm for the transpalpebral and 3 cm for the transciliary variant. The skin could be retracted 1.5 cm upward from the lower edge of the orbital rim with the transpalpebral and 2.5 cm upward with the transciliary variant. The craniotomy size was 2.5 × 1.5 cm for both variants, given that the transpalpebral variant included an orbital osteotomy. The bony opening in the transpalpebral variant was 1 cm more caudal; this restricted the craniocaudal working angles and, thereby, limited the achievable exposure of neurovascular structures in the paraclinoid area and along the sphenoid ridge.

CONCLUSION

If the orbital rim and the anterior aspect of the orbital roof are removed, then the transpalpebral variant of the SOC enables a bony opening that is just as large as that of the transciliary variant. Nonetheless, the more caudal location of the bony opening alters the available working angles and may impede exposure of key structures during aneurysm surgery.

Microneurosurgical treatment under the guidance of neuroendoscopy for an intracranial optic nerve Schwannoma: A case report

RATIONALE

Optic Schwannoma is rarely observed clinically as optic nerve had anatomically impossibility for the location of Schwannoma. However, several reports described the established cases of optic Schwannoma, of which the locations were in orbit or within optic canal. The occurrence of optic Schwannoma intracranially has been not reported.

PATIENT CONCERNS

A 60-year-old female complained of visual impairment in the right eye and the frequent headache and the dizziness over 2 years with unknown reasons. The result of magnetic resonance imaging (MRI) showed a round, well-circumscribed, heterogeneously enhancing signal with cystic change displayed on the right suprasellar cistern.

DIAGNOSES

Intracranial optic Schwannomas.

INTERVENTIONS

The patient accepted microneurosurgery assisted by endoscopy. We observed a gray and yellow lesion located near the right anterior clinoid process with a mid-sized cyst. And there was a vague boundary between the tumor and the right optic nerve which was compressed by the tumor. Optic chiasm and left optic nerve were also compressed. Meanwhile, the tumor had also adhesion to the right anterior cerebral artery (ACA).

OUTCOMES

After the tumor was totally resected, the patient had satisfactory recovery.

LESSONS

We reported an intracranial optic Schwannoma removal with the lateral supraorbital keyhole approach assisted by neuroendoscopy. Intracranial optic Schwannoma was rarely seen clinically. Neuroendoscopy imaging suggested the close relationship between the tumor and ACA, supporting vasculature-origin hypothesis for the optic Schwannoma.

Same viewing angle, minimal craniotomy enlargement, extreme exposure increase: the extended supraorbital eyebrow approach

The supraorbital eyebrow approach (SEa) has been commonly used as a straightforward route to reach lesions located in the anterior cranial fossa. The reduced surgical exposure provided by this approach limits its applicability. A modification of the SEa, the extended supraorbital eyebrow approach (X-SEa), allows use of the transylvian corridor to approach parasellar lesions, while maintaining most of the aesthetic advantages of the SEa. To quantify the surgical exposure and maneuverability provided by the X-SEa using a cadaveric study. Eleven heads were used to obtain all stereotactic measurements. Surgical exposure and maneuverability were measured by means of the area of exposure and the angles of attack along key representative points in the anterior circulation. The horizontal angle of attack at the middle cerebral artery provided by the X-SEa was larger than that provided by the SEa (32.6 vs 18.4°, p = 0.009). The X-SEa afforded broader vertical angles of attack at all targets in the anterior circulation (p < 0.05). The total area of exposure provided by the X-SEa was significantly larger than that provided by the SEa (1272 vs 978 ± 156 mm², p = 0.003). The area of exposure in the ipsilateral trigon and in the midline quadrangle was also significantly larger for the X-SEa (paramedian 195 vs 121 mm², p = 0.01; midline 1310 vs 778 mm², p = 0.002). The X-SEa increases the exposure and surgical maneuverability along the anterior and middle cranial fossa when compared to the standard SEa.

The endoscopic transpterional port approach: anatomy, technique, and initial clinical experience

OBJECTIVE

The evolution of microsurgical and endoscopic techniques has allowed the development of less invasive transcranial approaches. The authors describe a purely endoscopic transpterional port craniotomy to access lesions involving the cavernous sinus and the anterolateral skull base.

METHODS

Through single- or dual-port incisions and with direct endoscopic visualization, the authors performed an endoscopic transpterional port approach (ETPA) using a 4-mm straight endoscope in 8 sides of 4 formalin-fixed cadaveric heads injected with colored latex. A main working port incision is made just below the superior temporal line and behind the hairline. An optional 0.5- to 1-cm second skin port incision is made on the lateral supraorbital region, allowing multiangle endoscopic visualization and maneuverability. A 1.5- to 2-cm craniotomy centered over the pterion is done through the main port, which allows an extradural exposure of the cavernous sinus region and extra/intradural exposure of the frontal and temporal cranial fossae. The authors present a pilot surgical series of 17 ETPA procedures and analyze the surgical indications and clinical outcomes retrospectively.

RESULTS

The initial stage of this work on cadavers provided familiarity with the technique, standardized its steps, and showed its anatomical limits. The clinical ETPA was applied to gain access into the cavernous sinus, as well as for aneurysm clipping and meningioma resection. Overall, perioperative complications occurred in 1 patient (6%), there was no mortality, and at last follow-up all patients had a modified Rankin Scale score of 0 or 1.

CONCLUSIONS

The ETPA provides a less invasive, focused, and direct route to the cavernous sinus, and to the frontal and temporal cranial fossae, and it is feasible in clinical practice for selected indications with good results.