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

Neurologic and Neuropsychological Outcomes for Treatment of Unruptured Middle Cerebral Artery Aneurysms: Standard Pterional Versus Minipterional Approach in a Retrospective Single-Center Analysis

BACKGROUND

In accordance with technique advancement and minimal invasiveness surgical approaches, the minipterional has progressively replaced the standard pterional approach for treatment of unruptured middle cerebral artery (MCA) aneurysms. Nowadays, multimodal intraoperative resources including microDoppler and microflow probes, indocyanine green videoangiography, and neurophysiologic monitoring constitute a fundamental prerequisite for increasing the safety of the clipping procedure. Our study investigated and compared in a single-center experience the effect of the evolution of a minimally invasive and multimodal approach in unruptured MCA aneurysm surgery by measuring postoperative complication rate, recovery time, and long-term neuropsychological and functional outcomes.

METHODS

One hundred and thirty-one patients who underwent surgical treatment for unruptured MCA aneurysms at our institution were evaluated retrospectively. Patients' clinical, radiologic, and surgical reports were collected. Cognitive evaluation and quality of life were assessed through validated tests in telephone interviews. Patients who met the inclusion criteria were divided into 2 groups: "PT (pterional)" and "MPT (minipterional)."

RESULTS

Ninety-two patients were included in the analysis. A significant reduction of postoperative complication rates and new-onset postoperative seizures was recorded in the MPT group (P value = 0.006). Severe cognitive deficits were lower in the MPT group, although without a clear statistical correlation.

CONCLUSIONS

Decreased complication rates, faster recovery time, and a trend toward better cognitive and functional performances were documented for the MPT group of patients. In our experience, the minipterional approach with multimodality-assisted microsurgery reduced neurologic complications and recovery time and improved long-term cognitive outcome and quality of life.

Minimally invasive keyhole craniotomies for microsurgical clipping of cerebral aneurysms: comparative meta-analysis of the mini-pterional and supraorbital keyhole approaches

OBJECTIVE

Axel Perneczky is responsible for conceptualizing the "keyhole" philosophy as a new paradigm of minimal invasiveness within cranial neurosurgery. Keyhole neurosurgery aims to limit approach-related traumatization and minimize brain retraction while still enabling the neurosurgeon to achieve operative goals. The supraorbital keyhole craniotomy (SOKC) and minipterional (pterional keyhole, PKC) approaches have become mainstays for clipping intracranial aneurysms. While studies have compared these approaches to the traditional pterional craniotomy for clipping cerebral aneurysms, head-to-head comparisons of these workhorse keyhole approaches remain limited.

METHODS

The authors queried three databases per PRISMA guidelines to identify all studies comparing the SOKC to the PKC for microsurgical clipping of cerebral aneurysms. Of 148 unique studies returned on initial query, a total of 5 studies published between 2013 and 2019 met inclusion criteria. Where applicable, quantitative meta-analysis was performed via the Mantel-Haenszel method using Review Manager v5.4 (Nordic Cochrane Centre, Cochrane Collaboration, Copenhagen, Denmark). Risk of bias (ROB) was assessed using the Cochrane ROBINS-I tool, and all studies were assigned a Level of Evidence (I-V).

RESULTS

Across all five studies, the mean age ranged from 53.0 to 57.5 years old, and the cohort consisted of more females (n = 403, 60.6%) than males. The proportion of patients presenting with ruptured aneurysmal SAH was comparable between the SOKC and PKC cohorts (p = 0.43). Clipping rate [defined as the rate of successful aneurysm clip deployment with successful intraoperative occlusion] (OR 1.52 [0.49, 4.71], I2 = 0%, p = 0.47), final occlusion rates (OR 1.27 [0.37, 4.32], p = 0.70), and operative durations (SMD 0.33 [-0.83. 1.49], I2 = 97%, p = 0.58) were comparable regardless of approach used. Furthermore, rates of intraoperative rupture (OR 1.51 [0.64, 3.55], I2 = 0, p = 0.34), postoperative hemorrhage (OR 1.49 [0.74, 3.01], I2 = 0, p = 0.26), postoperative vasospasm (OR 0.94 [0.49, 1.80], I2 = 63, p = 0.86), and postoperative infection (OR 0.70 [0.16, 2.99], I2 = 0%, p = 0.63) were equivocal across SOKC and PKC cohorts.

CONCLUSION

The PKC and SOKC approaches appear to afford comparable outcomes when used for open microsurgical clipping of cerebral aneurysms in select patients with both ruptured and unruptured aneurysms. Both are associated with excellent clipping and occlusion rates, minimal perioperative complication profiles, and favorable postoperative neurologic outcomes. Further investigations are merited so clinicians can further parse out the indications and contraindications for each keyhole approach.

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.

The Pterional Keyhole Craniotomy Approach: A Historical Perspective

The pterional craniotomy is a workhorse of cranial surgery that provides access to the anterior and middle fossae. However, newer "keyhole" approaches, such as the micropterional or pterional keyhole craniotomy (PKC) can offer similar exposure for many pathologies while reducing surgical morbidity. The PKC is associated with shorter hospitalizations, reduced operative time, and superior cosmetic outcomes. Furthermore, it represents an ongoing trend toward smaller craniotomy size for elective cranial procedures. In this historical vignette, we trace the history of the PKC from its origins to its current role in the neurosurgeon's armamentarium.

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.

Outcomes and complications of cerebral aneurysms operated on by eyebrow incision according to aneurysm type and location

OBJECTIVE

Trans-eyebrow supraorbital aneurysmal neck clipping, also known as keyhole surgery, have many advantages of minimal invasive surgery. However, there are few studies on whether there is a difference in keyhole surgery according to the location of the aneurysm, and how the complications after keyhole approach differ from the conventional approach. The authors investigated the surgical outcome of keyhole aneurysmal surgery for clarify the characteristics of keyhole surgery.

METHODS

A retrospective study was performed with review of medical records and images of patients with anterior circulation aneurysm undergoing aneurysmal clipping with keyhole surgery. The patient's clinical condition, imaging, surgical condition, and outcome were investigated.

RESULTS

As a result of analysis about the location of the aneurysm, middle cerebral artery (MCA) aneurysm group had a longer operation time than internal carotid artery and anterior cerebral artery aneurysm groups, but there was no significant difference in complication rate. The olfactory dysfunction occurred more than that of conventional surgery and occurred less in MCA aneurysm group than others. Scalp sensory change in the surgical site was more common in patients with unruptured aneurysms.

CONCLUSION

By accurately investigating the frequency and severity of complications associated with trans-eyebrow aneurysmal neck clipping surgery, it can help to select a surgical approach considering risk versus benefit. In addition, patient's satisfaction can be increased by providing information to patients and caregivers in advance about the outcome of this approach and the anticipated complications.

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.

How I do it-Helsinki style mini-pterional craniotomy for clipping of middle cerebral artery bifurcation aneurysms

BACKGROUND

Different versions of the mini-pterional (MPT) approach have been described often with the idea the smaller the better. Attempts to reduce incision and craniotomy size for better cosmetic results should not be performed at the expense of safety.

METHOD

We present our take on the MPT as a balance between size and safety which can be adopted by vascular neurosurgeons in training. The craniotomy stays within the confines of the superior temporal line and is completely covered by temporal muscle after closure.

CONCLUSION

This approach is cosmetically superior while still offering anatomical familiarity and sufficient instrument maneuverability.

The sylvian keyhole approach for surgical clipping of middle cerebral artery aneurysms: Technical nuance to the minipterional craniotomy

Background

The minipterional (MPT) craniotomy is a workhorse approach for clipping of middle cerebral artery (MCA) aneurysms. Because it aims to reach the skull base, traction on the temporal muscle is required. As a result, patients may suffer from transient postoperative temporal muscle discomfort. The sylvian keyhole approach (SKA) represents an alternative craniotomy for the clipping of MCA aneurysms. The aims of this study are to describe the operative technique of the SKA and to discuss the benefits and disadvantages compared to the MPT craniotomy.

Methods

In this technical note, we report the experience gained with the SKA. This experience was acquired with virtual reality, 3D-printed models, and anatomical dissections. We also present two clinical cases.

Results

The SKA is centered on the distal sylvian fissure and tailored toward the specific MCA aneurysm. Traction to the temporal muscle is not necessary because access to the skull base is not sought. With the SKA, dissection of the MCA is performed from distal to proximal, aiming for a proximal control at the level of the M1-segment. The limen insulae was identified as a key anatomical landmark for approach selection. The SKA offers good surgical maneuverability when the aneurysm is located at the level or distal to the limen. The MPT craniotomy, however, remains the most appropriate approach when the aneurysm is located proximal to the limen.

Conclusion

The SKA represents a feasible and innovative alternative approach to the MPT craniotomy for surgical clipping of unruptured MCA aneurysms located at the level or distal to the limen insulae.

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.

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.

Neurosurgery outcomes and complications in a monocentric 7-year patient registry

Introduction

Capturing adverse events reliably is paramount for clinical practice and research alike. In the era of “big data”, prospective registries form the basis of clinical research and quality improvement.

Research question

To present results of long-term implementation of a prospective patient registry, and evaluate the validity of the Clavien-Dindo grade (CDG) to classify complications in neurosurgery.

Materials and methods

A prospective registry for cranial and spinal neurosurgical procedures was implemented in 2013. The CDG – a complication grading focused on need for unplanned therapeutic intervention – was used to grade complications. We assess construct validity of the CDG.

Results

Data acquisition integrated into our hospital workflow permitted to include all eligible patients into the registry. We have registered 8226 patients that were treated in 11994 surgeries and 32494 consultations up until December 2020. Similarly, we have captured 1245 complications on 6308 patient discharge forms (20%) since full operational status of the registry. The majority of complications (819/6308 ​= ​13%) were treated without invasive treatment (CDG 1 or CDG 2). At discharge, there was a clear correlation of CDG and the Karnofsky Performance Status (KPS, rho ​= ​-0.29, slope -7 KPS percentage points per increment of CDG) and the length of stay (rho ​= ​0.43, slope 3.2 days per increment of CDG).

Discussion and conclusion

Patient registries with high completeness and objective capturing of complications are central to the process of quality improvement. The CDG demonstrates construct validity as a measure of complication classification in a neurosurgical patient population.

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A prospective registry for cranial and spinal neurosurgical procedures was implemented in 2013.

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We have registered 8226 patients that were treated in 11994 surgeries and 32494 consultations up until December 2020.

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There was a clear correlation of CDG with the Karnofsky Performance Status and with length of hospital stay.

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The Clavien-Dindo grading (CDG) demonstrates construct validity as a measure of complication severity in a neurosurgical patient population.

VR-based training of craniotomy for intracranial aneurysm surgery

PURPOSE

Intracranial aneurysms can be treated micro-surgically. This procedure involves an appropriate head position of the patient and a proper craniotomy. These steps enable a proper access, facilitating the subsequent steps. To train the access planning process, we propose a VR-based training system.

METHOD

We designed and implemented an immersive VR access simulation, where the user is surrounded by a virtual operating room, including medical equipment and virtual staff. The patient's head can be positioned via hand rotation and an arbitrary craniotomy contour can be drawn. The chosen access can be evaluated by exposing the aneurysm using a microscopic view.

RESULTS

The evaluation of the simulation took place in three stages: testing the simulation using the think-aloud method, conducting a survey and examining the precision of drawing the contour. Although there are differences between the virtual interactions and their counterparts in reality, the participants liked the immersion and felt present in the operating room. The calculated surface dice similarity coefficient, Hausdorff distance and feedback of the participants show that the difficulty of drawing the craniotomy is appropriate.

CONCLUSION

The presented training simulation for head positioning and access planning benefits from the immersive environment. Thus, it is an appropriate training for novice neurosurgeons and medical students with the goal to improve anatomical understanding and to become aware of the importance of the right craniotomy hole.

Enhanced Recovery After Surgery strategies for elective craniotomy: a systematic review

OBJECTIVE

Enhanced Recovery After Surgery (ERAS) has led to a paradigm shift in perioperative care through multimodal interventions. Still, ERAS remains a relatively new concept in neurosurgery, and there is no summary of evidence on ERAS applications in cranial neurosurgery.

METHODS

The authors systematically reviewed the literature using the PubMed/MEDLINE, Embase, Scopus, and Cochrane Library databases for ERAS protocols and elements. Studies had to assess at least one pre-, peri-, or postoperative ERAS element and evaluate at least one of the following outcomes: 1) length of hospital stay, 2) length of ICU stay, 3) postoperative pain, 4) direct and indirect healthcare cost, 5) complication rate, 6) readmission rate, or 7) patient satisfaction.

RESULTS

A final 27 articles were included in the qualitative analysis, with mixed quality of evidence ranging from high in 3 cases to very low in 1 case. Seventeen studies reported a complete ERAS protocol. Preoperative ERAS elements include patient selection through multidisciplinary team discussion, patient counseling and education to adjust expectations of the postoperative period, and mental state assessment; antimicrobial, steroidal, and antiepileptic prophylaxes; nutritional assessment, as well as preoperative oral carbohydrate loading; and postoperative nausea and vomiting (PONV) prophylaxis. Anesthesiology interventions included local anesthesia for pin sites, regional field block or scalp block, avoidance or minimization of the duration of invasive monitoring, and limitation of intraoperative mannitol. Other intraoperative elements include absorbable skin sutures and avoidance of wound drains. Postoperatively, the authors identified early extubation, observation in a step-down unit instead of routine ICU admission, early mobilization, early fluid de-escalation, early intake of solid food and liquids, early removal of invasive monitoring, professional nutritional assessment, PONV management, nonopioid rescue analgesia, and early postoperative imaging. Other postoperative interventions included discharge criteria standardization and home visits or progress monitoring by a nurse.

CONCLUSIONS

A wide range of evidence-based interventions are available to improve recovery after elective craniotomy, although there are few published ERAS protocols. Patient-centered optimization of neurosurgical care spanning the pre-, intra-, and postoperative periods is feasible and has already provided positive results in terms of improved outcomes such as postoperative pain, patient satisfaction, reduced length of stay, and cost reduction with an excellent safety profile. Although fast-track recovery protocols and ERAS studies are gaining momentum for elective craniotomy, prospective trials are needed to provide stronger evidence.

Validation of the Clavien-Dindo grading system of complications for microsurgical treatment of unruptured intracranial aneurysms

OBJECTIVE

Microsurgery plays an essential role in managing unruptured intracranial aneurysms (UIAs). The Clavien-Dindo classification is a therapy-oriented grading system that rates any deviation from the normal postoperative course in five grades. In this study, the authors aimed to test the applicability of the Clavien-Dindo grade (CDG) in patients who underwent microsurgical treatment of UIAs.

METHODS

The records of patients who underwent microsurgery for UIAs (January 2013-November 2018) were retrieved from a prospective database. Complications at discharge and at short-term follow-up (3 months) were rated according to the Clavien-Dindo system. Patient outcomes were graded using the modified Rankin Scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS). A descriptive statistic was used for data analysis.

RESULTS

Overall, 156 patients underwent 157 surgeries for 201 UIAs (size range 4-42 mm). Thirty-nine patients (25%) had complex UIAs. An adverse event (CDG ≥ I) occurred in 21 patients (13.5%) by the time of discharge. Among these, 10 patients (6.4%) presented with a new neurological deficit. Significant correlations existed between a CDG ≥ I and an increase in mRS and NIHSS scores (p < 0.001). Patients treated for complex aneurysms had a significantly higher risk of developing new neurological deficits (20.5% vs 1.7%, p = 0.007). At the 3-month follow-up, a CDG ≥ I was registered in 16 patients (10.3%); none presented with a new neurological deficit. A CDG ≥ I was associated with a longer hospital length of stay (LOS) (no complication vs CDG ≥ I, 6.2 ± 3.5 days vs 9.3 ± 7.7 days, p = 0.02).

CONCLUSIONS

The CDG was applicable to patients who received microsurgery of UIAs. A significant correlation existed between CDG and outcome scales, as well as LOS. The aneurysm complexity was significantly associated with a higher risk for new neurological deficit.

Surgical Treatment of Intraorbital Lesions

BACKGROUND

Resection of pure intraorbital tumors is challenging owing to the nearness of the optic apparatus. The objective of this article was to report our experience with different intraorbital tumors and discuss classic approaches and obstacles.

METHODS

A retrospective case series of patients who underwent surgery for intraorbital tumors at a tertiary neurosurgical center between June 2007 and January 2020 was performed.

RESULTS

The study included 34 patients (median age 58 years; range, 18-87 years; 55.9% [19/34] female, 44.1% [15/34] male). Preoperative proptosis was observed in 67.6% (23/34); visual impairment, in 52.9% (18/34); diplopia, in 41.2% (14/34); and ptosis, in 38.3% (13/34). Intraconal tumors were found in 58.8% (20/34). The most common lesions were cavernous hemangiomas in 26.5% (9/34) and metastases in 14.7% (5/34). Gross total resection rate was 73.5% (25/34). Planned biopsy was performed in 14.7% (5/34). Median follow-up time was 15.5 months (interquartile range: 0-113 months). Surgical approaches included supraorbital approach (23.5% [8/34]), pterional approach (52.9% [18/34]), lateral orbitotomy (14.7% [5/34]), transnasal approach (5.9% [2/34]), and combined transnasal approach/lateral orbitotomy (2.9% [1/34]). Excluding planned biopsies, gross total resection was achieved in 80.0% (12/15) with pterional approach, 100% (7/7) with supraorbital approach, 80.0% (4/5) with lateral orbitotomy, and 100% (1/1) with transnasal approach/lateral orbitotomy. Complication rate requiring surgical intervention was 11.8% (4/34).

CONCLUSIONS

Considering the low operative morbidity and satisfactory functional outcome, gross total resection of intraorbital lesions is feasible. We support use of classic transcranial and transorbital approaches. More invasive and complicated approaches were not needed in our series.

When Is Diagnostic Subtraction Angiography Indicated Before Clipping of Unruptured and Ruptured Intracranial Aneurysms? An International Survey of Current Practice

INTRODUCTION

The goal of this survey is to investigate the indications for preoperative digital subtraction angiography (DSA) before clipping of ruptured and unruptured intracranial aneurysms in an international panel of neurovascular specialists.

METHODS

An anonymous survey of 23 multiple-choice questions relating to indications for DSA before clipping of an intracranial aneurysm was distributed to the international panel of attendees of the European-Japanese Cerebrovascular Congress (EJCVC), which took place in Milan, Italy on 7-9 June 2018. The survey was collected during the same conference. Descriptive statistics were used to analyze the data.

RESULTS

A total of 93 surveys were distributed, and 67 (72%) completed surveys were returned by responders from 13 different countries. Eighty-five percent of all responders were neurosurgeons. For unruptured and ruptured middle cerebral artery (MCA) aneurysms without life-threatening hematoma, approximately 60% of responders perform surgery without preoperative DSA. For aneurysms in other locations than MCA, microsurgery is done without preoperative DSA in 68% of unruptured and in 73% of ruptured cases. In cases of ruptured MCA or ruptured non-MCA aneurysms with life-threatening hematoma, surgery is performed without DSA in 97% and 96% of patients, respectively. Factors which lead to preoperative DSA being performed were: aneurysmal shape (fusiform, dissecting), etiology (infectious), size (>25 mm), possible presence of perforators or efferent vessels arising from the aneurysm, intra-aneurysmal thrombus, previous treatment, location (posterior circulation and paraclinoid aneurysm) and flow-replacement bypass contemplated for final aneurysm treatment. These are all factors that qualify an aneurysm as a complex aneurysm.

CONCLUSION

There is still a high variability in the surgeons' preoperative workup regarding the indication for DSA before clipping of ruptured and unruptured intracranial aneurysms, except for ruptured aneurysms with life-threatening hematoma. There is a general consensus among cerebrovascular specialists that any angioanatomical feature indicating a complex aneurysm should lead to a more detailed workup including preoperative DSA.

Midline Meningiomas of the Anterior Skull Base: Surgical Outcomes and a Decision-Making Algorithm for Classic Skull Base Approaches

Simple Summary

Resectioning midline meningiomas of the anterior skull base such as olfactory groove, planum sphenoidale, or tuberculum sellae is challenging, and determining the appropriate approach is important. Based on our experience with midline meningiomas, we propose a decision algorithm for choosing suitable transcranial approaches. With dichotomizing classic skull bases approaches into median and lateral ones, we display that median approaches provide satisfactory results for olfactory groove meningiomas, whereas lateral approaches enable sufficient exposure of the visual apparatus for planum sphenoidale meningiomas or tuberculum sellae meningiomas. This manuscript aims to point out the sufficiency and feasibility of classic transcranial techniques.

Abstract

(1) Background: Midline meningiomas such as olfactory groove (OGMs), planum sphenoidale (PSMs), or tuberculum sellae meningiomas (TSMs) are challenging, and determining the appropriate approach is important. We propose a decision algorithm for choosing suitable transcranial approaches. (2) Methods: A retrospective chart review between 06/2007 and 01/2020. Clinical outcomes, radiographic findings, and postoperative complication rates were analyzed with respect to operative approaches. (3) Results: We included 88 patients in the analysis. Of these, 18.2% (16/88) underwent an interhemispheric approach, 72.7% (64/88) underwent a pterional/frontolateral/supraorbital approach, 2.3% (2/88) underwent a unilateral subfrontal approach, and 6.8% (6/88) underwent a bifrontal approach. All OGMs underwent median approaches, along with one PSM. All of the other PSMs and TSMs were resected via lateral approaches. The preoperative tumor volume was ∅20.2 ± 27.1 cm³. Median approaches had significantly higher tumor volume but also higher rates of Simpson I resection (75.0% vs. 34.4%). An improvement of visual deficits was observed in 34.1% (30/88). The adverse event rate was 17.0%. Median follow-up was 15.5 months (range 0–112 months). (4) Conclusions: Median approaches provides satisfying results for OGMs, lateral approaches enable sufficient exposure of the visual apparatus for PSMs and TSMs. In proposing a simple decision-making algorithm, the authors found that satisfactory outcomes can be achieved for midline meningiomas.

Development of machine learning-based preoperative predictive analytics for unruptured intracranial aneurysm surgery: a pilot study

BACKGROUND

The decision to treat unruptured intracranial aneurysms (UIAs) or not is complex and requires balancing of risk factors and scores. Machine learning (ML) algorithms have previously been effective at generating highly accurate and comprehensive individualized preoperative predictive analytics in transsphenoidal pituitary and open tumor surgery. In this pilot study, we evaluate whether ML-based prediction of clinical endpoints is feasible for microsurgical management of UIAs.

METHODS

Based on data from a prospective registry, we developed and internally validated ML models to predict neurological outcome at discharge, as well as presence of new neurological deficits and any complication at discharge. Favorable neurological outcome was defined as modified Rankin scale (mRS) 0 to 2. According to the Clavien-Dindo grading (CDG), every adverse event during the post-operative course (surgery and not surgery related) is recorded as a complication. Input variables included age; gender; aneurysm complexity, diameter, location, number, and prior treatment; prior subarachnoid hemorrhage (SAH); presence of anticoagulation, antiplatelet therapy, and hypertension; microsurgical technique and approach; and various unruptured aneurysm scoring systems (PHASES, ELAPSS, UIATS).

RESULTS

We included 156 patients (26.3% male; mean [SD] age, 51.7 [11.0] years) with UIAs: 37 (24%) of them were treated for multiple aneurysm and 39 (25%) were treated for a complex aneurysm. Poor neurological outcome (mRS ≥ 3) was seen in 12 patients (7.7%) at discharge. New neurological deficits were seen in 10 (6.4%), and any kind of complication occurred in 20 (12.8%) patients. In the internal validation cohort, area under the curve (AUC) and accuracy values of 0.63-0.77 and 0.78-0.91 were observed, respectively.

CONCLUSIONS

Application of ML enables prediction of early clinical endpoints after microsurgery for UIAs. Our pilot study lays the groundwork for development of an externally validated multicenter clinical prediction model.

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.

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.

Comparative anatomical analysis between the minipterional and supraorbital approaches

OBJECTIVE

Keyhole approaches, namely the minipterional approach (MPTa) and the supraorbital approach (SOa), are alternatives to the standard pterional approach to treat lesions located in the anterior and middle cranial fossae. Despite their increasing popularity and acceptance, the indications and limitations of these approaches require further assessment. The purpose of the present study was to determine the differences in the area of surgical exposure and surgical maneuverability provided by the MPTa and SOa.

METHODS

The areas of surgical exposure afforded by the MPTa and SOa were analyzed in 12 sides of cadaver heads by using a microscope and a neuronavigation system. The area of exposure of the region of interest and surgical freedom (maneuverability) of each approach were calculated.

RESULTS

The area of exposure was significantly larger in the MPTa than in the SOa (1250 ± 223 mm2 vs 939 ± 139 mm2, p = 0.002). The MPTa provided larger areas of exposure in the ipsilateral and midline compartments, whereas there was no significant difference in the area of exposure in the contralateral compartment. All targets in the anterior circulation had significantly larger areas of surgical freedom when treated via the MPTa versus the SOa.

CONCLUSIONS

The MPTa provides greater surgical exposure and better maneuverability than that offered by the SOa. The SOa may be advantageous as a direct corridor for treating lesions located in the contralateral side or in the anterior cranial fossa, but the surgical exposure provided in the midline region is inferior to that exposed by the MPTa.

The extradural minipterional approach for the treatment of paraclinoid aneurysms: a cadaver stepwise dissection and clinical case series

Minipterional (MPT) craniotomy has recently been added to the neurosurgical armamentarium as a less invasive alternative to the pterional craniotomy for the treatment of parasellar lesions. However, its clinical applicability in the treatment of certain complex aneurysms, such as those arising in the paraclinoid region, remains unclear. To illustrate the microsurgical anatomy of a modified extradural MPT approach, which combines a classic MPT craniotomy with an extradural anterior clinoidectomy, and to demonstrate its clinical applicability in the treatment of complex paraclinoid aneurysms. A stepwise extradural MPT approach is illustrated in a cadaver study. Clinical outcome data from a series of 19 patients with 20 paraclinoid aneurysms treated surgically using the extradural MPT approach between 2016 and 2018 were retrospectively collected. In 95% of the cases, complete aneurysm occlusion was achieved. No aneurysm recurrences were seen during follow-up with a median length of 21 months. The outcome, according to the modified Rankin Scale, was 0 points in 12 patients (63%), 1 point in 6 patients (32%), and 2 points in 1 patient (5%). Four out of 6 patients (67%) with initial visual symptoms showed improvement following treatment, whereas in two (11%), vision became worse. The extradural MPT approach ensures a sufficiently large exposure of the paraclinoid region that is comparable with conventional approaches with the advantage of being minimally invasive. Our case series demonstrates the feasibility of this approach for the treatment of complex paraclinoid aneurysms.