Minipterional and Supraorbital Keyhole Craniotomies for Ruptured Anterior Circulation Aneurysms: Experience at Single Center

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.

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.

Microsurgical Clipping of Multiple Intracranial Aneurysms via the Keyhole Approach

BACKGROUND

Keyhole surgery has been widely used to clip various intracranial aneurysms. Here, the feasibility of microsurgical clipping of multiple intracranial aneurysms via the keyhole approach was further investigated.

METHODS

The clinical data of 80 patients with multiple intracranial aneurysms treated with keyhole surgery were retrospectively analyzed. The patients included 25 males and 55 females, with an average age of 57.5 years. There were 13 patients with unruptured aneurysms, 67 patients with ruptured aneurysms (small aneurysms accounted for 52.2% of ruptured aneurysms), and a total of 198 aneurysms. A 4 cm incision and a bone hole of approximately 2.5 cm were used per craniotomy standards. Forty-eight cases were treated via the supraorbital keyhole approach, 45 cases via the pterional keyhole approach, and 3 cases via the interhemispheric keyhole approach.

RESULTS

A bilateral and unilateral keyhole approach was applied in 18 and 62 cases, respectively. A total of 170 ipsilateral and 7 contralateral aneurysms were clipped. The complete clipping rate was 98.9%. During the follow-up period of 6-12 months after surgery, the Glasgow outcome scale score was 5 points in 74 cases, 4 points in 5 cases, and 3 points in 1 case. The prognosis was associated with the preoperative Hunt-Hess classification but not with the number of operative sides, the operation opportunity, or the number of clipped aneurysms.

CONCLUSION

Early keyhole surgical clipping of multiple intracranial aneurysms is an effective treatment. Among ruptured aneurysms, small aneurysms are common and need attention and timely treatment.

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.

Cosmetic Outcomes of Supraorbital Keyhole Craniotomy Via Eyebrow Incision: A Systematic Review and Meta-Analysis

Background  Supraorbital eyebrow craniotomy is a minimally invasive alternative to a frontotemporal craniotomy and is often used for tumor and vascular pathologies. The purpose of this study was to investigate how patient cosmetic outcomes are affected by technique variations of this approach. Methods  PubMed, Embase, and Scopus databases were systematically searched, and results were reported according to PRISMA guidelines. For the meta-analysis portion, the DerSimonian-Laird random effects model was used, and the primary end points were patient satisfaction and percentage of permanent cosmetic complications. Results  A total of 2,629 manuscripts were identified. Of those, 124 studies (8,241 surgical cases) met the inclusion criteria. Overall, 93.04 ± 11.93% of patients reported favorable cosmetic outcome following supraorbital craniotomy, and mean number of cases with permanent cosmetic complications was 6.62 ± 12.53%. We found that vascular cases are associated with more favorable cosmetic outcomes than tumor cases ( p  = 0.0001). Addition of orbital osteotomy or use of a drain is associated with adverse cosmetic outcomes ( p  = 0.001 and p  = 0.0001, respectively). The location of incision, size of craniotomy, utilization of an endoscope, method of cranial reconstruction, skin closure, use of antibiotics, and addition of pressure dressing did not significantly impact cosmetic outcomes ( p  > 0.05 for all). Conclusions  Supraorbital craniotomy is a minimally invasive technique associated with generally high favorable cosmetic outcomes. While certain techniques used in supraorbital keyhole approach do not pose significant cosmetic risks, utilization of an orbital osteotomy and the addition of a drain correlate with unfavorable cosmetic outcomes.

Anatomical Justification of Extradural Resection of the Anterior Clinoid Process

Objective  The study aimed to provide neuroanatomical justification of the extradural resection of the anterior clinoid process (ACP). Material and Method  Using a cross-sectional study design, 47 cranial computed tomography (CT) scans were examined. There were 31 (65.96%) females aged 28 to 79 years. The measured dimensions were ACP length and width, and optic strut (OS) width. Index (i acp ) was measured as the ratio of ACP width to ACP length. The ACP volume and working operating field (WOF) volume were measured using Syngo.via Siemens program. The percentage expansion of WOF after removal of the ACP was estimated on 5 fixed human cadaver heads with the exoscope VITOM 3D. The possibilities of the combined approach were demonstrated in a clinical case. Results  The mean ACP lengths were 11.31 ± 2.76 and 11.54 ± 2.86 mm, on the right and left, respectively. The mean ACP widths were 7.70 ± 1.66 and 7.64 ± 1.67 mm, on the right and left, respectively. Average i acp was 0.67 (minimum 0.45; maximum 0.90). The width of the OS varied in the range from 1.37 to 4.75 mm. The average volume of right ACP was 0.71 ± 0.16 cm 3 , right WOF was 3.26 ± 0.74 cm 3 , left ACP was 0.71 ± 0.15 cm 3 , left and WOF was 3.20 ± 0.76 cm 3 . Removal of the right ACP expanded the right WOF by 22.21 ± 3.88%, and left ACP by 22.78 ± 5.50%. There was an approximately 25% increase in the WOF from the cadaveric dissections. Taking into account the variability of the ACP and OS, we proposed our own surgical classification of complicated (i acp ≥ 0.67; medium OS 2.5 mm ≤ 4.0 mm; wide OS ≥ 4.0 mm; ACP with pneumatization) and uncomplicated ACP (i acp 0.45 ≤ 0.67 mm; i acp ≤ 0.45; narrow OS ≤ 2.5 mm; ACP without pneumatization). Using this classification, we developed an algorithm for ACP dissection and removal. This was piloted in a clinical case of microsurgical clipping of a left internal carotid artery-posterior communicating artery aneurysm via the left minipterional approach. Conclusion  Extradural removal of ACP expands the WOF by approximately 25%, it helps neurosurgeons to improve proximal vascular control and avoid complications, and expands the range of indications for neurosurgical interventions in the skull base area.

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.

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.

Presurgical selection of the ideal aneurysm clip by the use of a three-dimensional planning system

Aneurysm occlusion rate after clipping is higher than after endovascular treatment. However, a certain percentage of incompletely clipped aneurysms remains. Presurgical selection of the proper aneurysm clips could potentially reduce the rate of incomplete clippings caused by inadequate clip geometry. The aim of the present study was to assess whether preoperative 3D image-based simulation allows for preoperative selection of a proper aneurysm clip for complete occlusion in individual cases. Patients harboring ruptured or unruptured cerebral aneurysms prior to surgical clipping were analyzed. CT angiography images were transferred to a 3D surgical-planning station (Dextroscope®) with imported models of 58 aneurysm clips. Intracranial vessels and aneurysms were segmented and the virtual aneurysm clips were placed at the aneurysm neck. Operating surgeons had information about the selected aneurysm clip, and patients underwent clipping. Intraoperative clip selection was documented and aneurysm occlusion rate was assessed by postoperative digital subtraction angiography. Nineteen patients were available for final analysis. In all patients, the most proximal clip at the aneurysm neck was the preselected clip. All aneurysms except one were fully occluded, as assessed by catheter angiography. One aneurysm had a small neck remnant that did not require secondary surgery and was occluded 15 months after surgery. 3D image-based preselection of a proper aneurysm clip can be translated to the operating room and avoids intraoperative clip selection. The associated occlusion rate of aneurysms is high.

Supraorbital Keyhole Craniotomy in Pediatric Neurosurgery: A Systematic Review of Clinical Outcomes and Cosmetic Outcomes

BACKGROUND

Supraorbital keyhole craniotomy is a minimally invasive approach used to access the parasellar region with advantages of decreased cortical exposure, simple closure, and decreased risk of postoperative cerebrospinal fluid leak. The incision of this approach, however, has raised cosmetic concerns, especially for pediatric patients. The aim of this study is to assess postoperative complications and cosmeses of the supraorbital keyhole approach for resection of intracranial lesions in pediatric patients.

METHODS

A literature search of PubMed, Scopus, and Web of Science databases was performed on June 1, 2021, searching for all studies of pediatric patients undergoing supraorbital keyhole craniotomy for surgical resection of lesions in the anterior fossa/sellar region.

RESULTS

Of 729 unique hits, 15 supraorbital keyhole studies reporting on 177 pediatric cases were included in the final review. Quality of all included studies was moderate. Overall, the surgery was well tolerated with a low number of severe adverse events. A wide variety of pathologies were treated with this approach. Complications of surgery included changes in vision, epidural hematoma, subdural hematoma, cerebrospinal fluid leak, and wound infection. At 6 weeks of follow-up, surgical scars in most patients were noted to be minimally detectable. At 3-6 months of follow-up, scars were no longer visible. Cosmetic complications included 5 bone defects, 1 split eyebrow, and 1 case of ptosis.

CONCLUSIONS

This study suggests that supraorbital keyhole craniotomy is a safe and effective approach to access the parasellar region in pediatric patients with excellent cosmetic outcomes reported across multiple institutions.

Keyhole approach in anterior circulation aneurysm: Current indication, advantages, technical limitations, complications and their avoidance

Keyhole surgery recently evolved as a minimal invasive surgical approach for treatment of anterior circulation aneurysm. This review was done to evaluate the keyhole approach for anterior circulation aneurysms, their indications, advantages, technical limitations, complications and their avoidance. The literature review was performed with the phrase "keyhole approach for anterior circulation aneurysm" as a search term in PubMed central, Medline, Google scholar and Embase data base to identify all the articles published till December 2020. Out of 113 articles searched, 22 were included in this review after screening for eligibility. On analyzing these articles, there was total 2058 aneurysm in 1871 patients. Out of 2058 aneurysm, 988 were ruptured and 547 unruptured. In 5 studies, which include 344 aneurysms in 344 cases, aneurysm ruptured or unruptured status was not specified. The most frequent aneurysm site was anterior communicating artery (n=573). The size of the aneurysm mentioned in most of the study was <15 mm. The rate of complete occlusion was ranged from 93.6-100%. The range of intra operative rupture (IOR) was 0-28.6%. The mean operative time was ranged from 70 min-5.34 hours as reported in 13 studies. Good outcome [Glasgow outcome scale (GOS): 4-5] were seen in 75-100% cases. The frontalis muscle weakness has been reported in 3 studies and ranged from 0-1.99%. Keyhole surgery can be a safe and effective treatment modality for treatment of a selected anterior circulation aneurysm. In the experienced hand it has certain advantages over standard pterional craniotomy.

Supraorbital Keyhole Craniotomy via Eyebrow Incision: A Systematic Review and Meta-Analysis

BACKGROUND

Supraorbital eyebrow keyhole craniotomy is a minimally invasive alternative to a frontotemporal craniotomy and is often used for tumor resection and aneurysm clipping. The purpose of this study is to provide a contemporary review on the outcomes related to this approach and to determine whether they vary with the type of pathology and the addition of an endoscope.

METHODS

PubMed, Embase, and Scopus databases were systematically searched, and results were reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. For the meta-analysis portion, the DerSimonian-Laird random effects model was used.

RESULTS

A total of 2629 manuscripts were identified. of those, 124 studies (8241 surgical cases) met the inclusion criteria. Mean total complication rate was 26.7 ± 25.7% and the mean approach-related mortality rate was 1.3 ± 2.8%. Technical success, defined as gross total tumor resection or complete aneurysm clipping, was achieved in 83.6 ± 21.5% of the cases. Vascular pathologies were associated with greater technical success, lower total complications, and longer length of hospital stay compared with tumor cases (P < 0.05 for all). For vascular cases, addition of the endoscope yielded lower technical success (P = 0.001) and lower complication rate (P = 0.041). The use of the endoscope for tumor pathologies did not affect technical success, complications, mortality, length of hospital stay, operative time, or reoperation rate (P > 0.05).

CONCLUSIONS

The supraorbital craniotomy via an eyebrow incision is a feasible minimally invasive approach with an overall high technical success rate for both vascular and tumor pathologies.

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.

Comparative study between minimally invasive supraorbital craniotomy and pterional craniotomy for treating anterior circulation cerebral aneurysms in a low-resource setting

The challenges encountered in performing minimally invasive approaches, such as supraorbital minicraniotomy (SOMC), in services without adequate equipment are rarely reported in the literature. This study analyzes the viability of SOMC in the treatment of cerebral aneurysms, using exactly the same resources as pterional craniotomy (PC). The results of these two techniques are compared. 35 patients underwent SOMC, compared to 50 patients underwent CP (100 aneurysms in total), using the same microsurgical instruments. The following variables were compared: operative time, angiographic cure, length of intensive care unit stay during the post-operative period, surgical complications, length of hospital stay after surgery until hospital discharge, intraoperative aneurysm rupture, aesthetic satisfaction with the scar, and neurological status at discharge. SOMC had a significantly shorter operative time in relation to PC (213.9 ± 11.09 min and 268.6 ± 15.44 min, respectively) (p = 0.0081).With respect to the cosmetic parameters assessed by the Visual Analog Scale, the average for SOMC was 94.12 ± 1.92 points, and the average for PC was 83.57 ± 4.75 points (p = 0.036). SOMC was as effective as PC in relation to successful aneurysm clipping (p = 0.77). The SOMC technique did not show advantages over PC in any other variable. Even in a general neurosurgery service lacking a specific structure for minimally invasive surgeries, SOMC was feasible and effective for treating intracranial aneurysms, using the same set of microsurgical instruments used for PC, obtaining better results in operating time and cosmetic satisfaction.

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 extended eyebrow approach: A cadaveric feasibility study

INTRODUCTION

Extradural anterior clinoidectomy (eAC) is key to expose the paraclinoid region. Several authors have pointed limitations of performing an eAC through a supraorbital craniotomy. In this article, we aim to provide educational material and discuss the technical nuances to successfully perform an eAC throughout a modification of the supraorbital approach, the extradural extended eyebrow approach (xEBA+eAC).

METHODS

Four embalmed heads were used for anatomic dissection and perform the xEBA+eAC. Additionally, one head was used for a video demonstration of the surgical approach.

RESULTS

The anterior clinoid process was successfully removed, and the ophthalmic artery and paraclinoid region were exposed in all specimens. Drilling the sphenoid wing until exposing the meningo-orbital band and further interdural dissection are vital steps to expose the anterior clinoid process. Removal of the anterior clinoid process can be simplified in 3 osteotomies, including the optic canal unroofing, detachment from the lateral pillar, and drilling of the optic strut. Sectioning of the distal dural ring facilitates the mobilization of the internal carotid artery and the surgical exposure of the ophthalmic artery.

CONCLUSIONS

xEBA+eAC is a technically feasible approach that provides exposure to the paraclinoid region, along with anterior and middle cranial fossa.

The transsylvian corridor through minimally invasive transcranial approaches: a comparative anatomical study

Minimally invasive transcranial approaches (MITAs) continue to expand in popularity in neurosurgery. Only few MITAs allow sufficient sylvian exposure to enable wide use of the transsylvian corridor. In this study, we aim to compare the transsylvian corridor in two MITAs: the minipterional (MPTa) and the extended supraorbital eyebrow approaches (XSEa). Eight cadaver heads were used to quantify the surgical exposure and maneuverability along the sylvian fissure and the insular lobe provided by the MPTa and the XSEa. Surgical exposure was calculated by means of the exposed length of the sylvian fissure and by the area framed within three extreme points in the insular lobe. Maneuverability was assessed by means of the surgical freedom along the sylvian cistern. XSEa provides twice the frontal exposure and half of the temporal exposure in comparison to the MPTa (p < 0.001 and p = 0.02, respectively). No significant differences were found between the two craniotomies in the length of the exposure of the sylvian fissure, area of insular exposure, or surgical freedom. Both the MPTa and the XSEa afford sufficient grades of exposure along the sylvian fissure and the insular lobe, although the viewing angle is significantly different between the two approaches. Such properties allow either to be used for microsurgery deep within the sylvian cistern. The use of additional corridors, such as the subfrontal route (XSEa) and pretemporal route (MPTa), may influence selection of either the minipterional or the extended supraorbital approaches according to the origin of the surgical pathology addressed.

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 Keyhole Approach in Anterior Circulation Aneurysm - Current Indication and Limitation with Review of Literature

Introduction:

The keyhole approach has been an emerging technique for cerebral aneurysm surgery in the past two decades. The preoperative simulation and tailored-made approach for each patient make feasible to clip many cerebral aneurysms via keyhole approach. In our study, we reviewed the previous experiences of the keyhole approach, related specifically for anterior circulation aneurysm.

Material and Methods:

The comprehensive literature review was performed on PubMed, Google Scholar, ScienceDirect, and various neurosurgery and neurology journals. Then, each manuscript's reference list was reviewed for the potential relevant article. The data of total 17 articles, which met our inclusion criteria included for the final review.

Results:

It was found that the anterior communicating artery, middle cerebral artery, and internal carotid- posterior communicating aneurysms were the most common locations treated by keyhole approach. The size of an aneurysm was <10 mm in most of the studies. Many studies treated multiple aneurysms by single keyhole approach.

Conclusion:

The keyhole approach has shown benefit in term of satisfactory aneurysmal occlusion rate, short operative time, less blood loss, short hospital stay, and good overall surgical outcome.

Meta-Analysis of Pterional Versus Supraorbital Keyhole Approach for Clipping Intracranial Aneurysms: Direct Comparison of Approach-Related Complications

BACKGROUND

The supraorbital keyhole approach (SKA) and pterional approach (PA) have been recommended for clipping intracranial aneurysms (IAs). We conducted a meta-analysis to systematically and comprehensively compare the clinical outcomes between the 2 approaches.

METHODS

We retrieved potential academic studies that had compared the clinical outcomes of SKA and PA for clipping IAs from the Cochrane Library, Medline, PubMed, and EMBASE databases. The references of the identified studies were carefully reviewed to ensure that all available documents had been included in the present study. The meta-analysis was conducted in accordance with the acknowledged PRISMA (prioritized reported items for systematic review and meta-analysis) guidelines.

RESULTS

A total of 8 studies with 1016 participants were included in our study. Of these 1016 patients with IAs, 518 were assigned to the SKA group and 498 to the PA group. Our results showed that the SKA is preferable for clipping IAs compared with the PA because of its shorter operative time (weighted mean difference, -3.163; 95% confidence interval [CI], -5.577 to -0.749; P = 0.01) and length of stay, especially for the patients with unruptured IAs (weighted mean difference, -52.107; 95% CI, -81.597 to -22.618). However, a lower risk of postoperative infection was found in the SKA group (4.6% vs. 8.5%; odds ratio, 0.398; 95% CI, 0.186-0.850; P = 0.017), which seemed to derive from the ruptured IAs (OR, 0.330; 95% CI, 0.136-0.800; P = 0.014). However, no significant difference was found in the incidence of frontal sinus opening, completed occlusion, procedural complications, intraoperative rupture, postoperative hematoma, or cerebral vessel spasm.

CONCLUSIONS

The SKA was associated with a shorter length of stay and operation time and a lower risk of postoperative infection. Hence, the SKA seems to be equally effective and safe for clipping IAs compared with PA and should be recommended for surgeons who have acquired sufficient experience with this technique owing to its advantages compared with the PA.

Quantitative Anatomic Study of the Minipterional Craniotomy in the Paraclinoid Region: Benefits of Extradural Anterior Clinoidectomy

BACKGROUND

Extradural anterior clinoidectomy (eAC) via the minipterional craniotomy (MPT) approach (MPT+eAC) has been recently introduced to the neurosurgical armamentarium to improve access to anterior and middle fossa skull base structures using a minimally invasive approach. However, the effect of extradural clinoidectomy on surgical exposure with the minipterional approach has not been evaluated. Moreover, the effect of eAC on surgical maneuverability has not been established for either traditional pterional or minipterional craniotomy. We sought to illustrate the microsurgical anatomy of the MPT+eAC and to evaluate the effect of eAC on surgical exposure and maneuverability.

METHODS

The area of exposure, area of surgical freedom, and maneuverability score for the MPT approach and MPT+eAC were compared in 5 cadaveric heads.

RESULTS

Compared with the MPT approach, the MPT+eAC enlarged the area of exposure approximately twofold (93 cm² vs. 184 cm²; P < 0.001). All targets considered in the paraclinoid region, including the posterior communicating artery origin, prechiasmatic region, and ophthalmic artery origin, showed an increase in surgical freedom and maneuverability after performing eAC. Targets remote from the clinoid such as the internal carotid bifurcation were not affected.

CONCLUSIONS

MPT+eAC offers a larger area of exposure and greater surgical freedom and maneuverability at the paraclinoid region using this minimally invasive approach.

Supraorbital keyhole approach: Pure endoscopic and endoscope-assisted perspective

OBJECTIVE

To assess the assumed advantages of pure endoscopic and endoscope-assisted methods for the supraorbital keyhole approach. The aim is to demonstrate visibility and accessibility of the pure endoscope approach as a possible standard approach for the supraorbital keyhole approach.

PATIENTS AND METHODS

We performed eight dissections on four cadaver heads using an operating microscope, an endoscope, and neuronavigation. The visibility and accessibility of the anterior and middle cranial fossae regions were compared for each. Special structures were defined to assess their preservation in both approaches. We used pure endoscopy on the eight sides and with a microscope on those same eight sides. Accessibility was quantified for key structures using linear measurements taken with the navigation system. In addition, we present clinical cases in which an endoscope-assisted supraorbital approach was employed.

RESULTS

Our measurements have been reported for each side in the formalin-fixed heads as the mean ± SD (in mm) from the bone margin to selected regions. Moreover, image analysis was performed using ImageJ software to compare selected surface area measurements between the endoscope and microscope images on each side for all cadaveric available specimens. There were no significant statistical differences between visualization of the selected areas. This means that by visual analysis both endoscopic and microscopic images can provide the surgeon nearly the same visibility and accessibility of a selected region.

CONCLUSION

A pure endoscopic method can be used to conduct the supraorbital keyhole approach when the endoscope is used as a primary tool. Our recommendation is to use the measurements described in this study for preoperative planning of the keyhole approach. We believe that with advances in neuro-endoscope technology, and instrumentations, the endoscopic approach may replace the microscopic approach in the near future.

Supraorbital Keyhole Approach for Intracranial Aneurysms : Transitioning from Concerns to Confidence

For surgical minimalism to reduce iatrogenic traumatization, a supraorbital keyhole approach has already been successfully applied to treat many unruptured anterior circulation aneurysms. However, using this minimal approach also raises several technical concerns due to the small cranial opening and cosmetic impact of a facial incision. Yet, such technical limitations can be overcome by using favorable surgical indications, slender surgical instruments, and optimized surgical techniques, while excellent cosmetic outcomes can be achieved using a short skin incision located <1 cm from the supraorbital margin, reconstruction of any bone defects around the bone flap, and meticulous wound closure. Thus, given such reassuring surgical results, in terms of the clipping status, neurological effects, and cosmetic outcomes, any concerns can be transitioned into confidence.

Transblepharo-Preseptal Modified Orbitozygomatic Approach for the Treatment of Ruptured Proximal Anterior Circulation Aneurysms

BACKGROUND

Minimally invasive skull base approaches, including the cosmetically optimal transblepharo-preseptal modified orbitozygomatic (TBMOZ) technique, have been described to treat proximal anterior circulation aneurysms. The use of minimally invasive techniques for previously ruptured aneurysms is rare because of perceived technical challenges in controlling intraoperative ruptures. Herein, we determine the utility of the minimally invasive TBMOZ approach for the treatment of ruptured proximal anterior circulation aneurysms.

METHODS

A retrospective analysis of an institutional review board-approved, prospective database was performed to identify patients with ruptured anterior circulation aneurysms treated with a TBMOZ approach. Patient demographics, aneurysm characteristics, temporary clip time, intra-operative ruptures, and neurologic outcomes were recorded.

RESULTS

Fifteen patients (9 females, 6 males; average age, 53.6 ± 12.2 years) underwent a TBMOZ craniotomy following subarachnoid hemorrhage for clipping of 17 aneurysms (12 anterior communicating, 3 posterior communicating, and 2 carotid terminus). Four of 15 patients (26.6%) experienced intraoperative rupture, which was easily controlled in all patients and did not affect clinical outcomes. All patients had complete aneurysm ablation confirmed on postoperative cerebrovascular imaging. Good neurologic outcomes (Glasgow Outcome Score [GOS] of 5) were achieved in 73.3% (n = 11) of patients at time of hospital discharge; the remaining patients had a GOS of 3-4. No patients experienced frontalis muscle weakness or facial nerve injuries, and all patients had acceptable cosmetic outcomes. One patient (6.6%) experienced a surgery-related complication: postoperative versus vasospasm-induced perforator infarcts.

CONCLUSIONS

The TBMOZ approach provides a minimally invasive option for the safe treatment of previously ruptured proximal anterior circulation aneurysms.