Retractorless Surgery for Anterior Circulation Aneurysms via a Pterional Keyhole Approach

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.

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.

Retractorless Surgery for Petroclival Meningiomas via the Subtemporal Approach: A Try to Reduce Brain Retraction Injury

Purpose

To present our experience with retractorless surgery for resection of petroclival meningiomas (PCMs) via the subtemporal approach with routine operative instruments.

Methods

Clinical data of patients with PCMs who received surgical treatments via subtemporal approach were retrospectively analyzed. Patient demographics, duration of operation, extent of resection, postoperative brain injury rate, postoperative complication, and surgical outcome were reviewed.

Results

Twenty-nine consecutive patients with retractorless surgery via subtemporal approach performed between November 2018 and November 2021. The gross total resection rate was 82.8% (N = 24). The incidence of postoperative temporal lobe injury was 3.4% (N = 1). All the procedures were completed without fixed retraction or other specialized instruments.

Conclusions

Retractorless surgery via subtemporal approach is a reliable treatment option for PCMs, which can be completed with routine operative instruments.

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.

[Brain retraction injury]

This review is devoted to various techniques for reduction of brain damage during retraction. Searching for reports was carried out in Russian and English languages using the PubMed database (n=721) without restrictions on language, date and study design according to the following keywords: «brain retraction injury», «spatula brain retractors», «tubular brain retractors», «retractorless neurosurgery». Primary screening and exclusion of duplicate manuscripts allowed us to single out the main group of articles (n=121). Some reports were excluded due to non-compliance with inclusion criteria (no description of methods, few references and insufficient data). The final list included 32 studies which were represented by cohort studies, retrospective analyses of surgical interventions, as well as experimental and laboratory studies. Small number of publications did not allow us to obtain unambiguous conclusions. Further research is required to reduce brain retraction trauma.

Retractorless brain surgery: technical considerations

Background

Retraction is necessary to access deep areas in the brain and skull base, but prolonged and forceful use of fixed retraction might be injurious. Several techniques were developed, in the concept of minimally invasive neurosurgery, to eliminate or minimize the use of fixed retractors. The authors discuss the technical considerations and limits in applying dynamic retraction in brain surgery for a variety of lesions using different approaches.

Results

We retrospectively collected 123 cases with brain lesions in diverse locations, were dynamic retraction, using the tools in the operator hands and was achieved successfully instead of fixed retraction. Cases with aneurysms were excluded, although retraction was applied during clipping only. Superficial and large masses that do not require fixed retraction as a routine were excluded also. We relied mainly on patient positioning to benefit from the gravity, proper design of the craniotomy, arachnoid dissection, cerebrospinal fluid aspiration, and internal decompression of the mass when possible.

Different approaches for different lesions were utilized in our patients, subfrontal or pterional and their modifications in 45.5% of cases, suboccipital in 21.1%, retrosigmoid in 13%, the interhemispheric approach in 10.5%, transcortical to lateral ventricles in 7.3%, and posterior subtemporal in 2.4%.

Dynamic retraction with the surgical tools was used successfully in all cases except 7 patients (5.6%) where we had to use fixed retraction transiently.

Conclusion

Several considerations are helpful and amenable to achieve successful brain surgery without fixed retraction. Utilizing the gravity, unlocking of the brain, choosing the surgical corridor, cerebrospinal fluid suctioning, and mastering of the microsurgical techniques are the keys.

Application of three dimensional (3D) curved multi-planar reconstruction images in 3D printing mold assisted eyebrow arch keyhole microsurgery

OBJECTIVE

The application of multi-planar reconstruction of three dimensional (3D) curved surface in microsurgery of 3D printing mold assisted eyebrow arch keyhole approach was studied.

METHODS

Eighty patients with intracranial aneurysms who underwent treatment at our hospital were enrolled. The patients were divided into two groups: the traditional eyebrow keyhole approach microsurgery group (38 cases in the conventional treatment group) and the three-dimensional curved surface multi-plane reconstruction image combined with 3D printing technology assisted eyebrow keyhole approach microsurgery group (42 cases in the 3D printing assisted treatment group). The Hunt-Hess classification was used to make a preliminary estimation of the patient's condition. The 3D curved multi-planar reconstruction method was used to assist the surgical plan; CT scan was used to establish a 3D printing mold, and the patient's condition and surgical plan were accurately analyzed before surgery. The operative time and the size of the incision area were recorded; postoperative GOS score and postoperative complications were statistically investigated.

RESULTS

The 3D printing assisted treatment group (70.13 ± 15.56), (411.26 ± 10.38) mm² , the operative time and incision area were significantly shorter than the conventional treatment group (120.35 ± 20.46), (663.55 ± 13.54) mm² , p < .05); the GOS score showed that the 3D printing-assisted treatment group was significantly higher than the conventional treatment group (p < .05). The postoperative complication rate was significantly lower in the 3D print-assisted treatment group (9.52%) than in the conventional treatment group (47.36%, p < .05); the cure of intracranial aneurysms in the 3D printing assisted treatment group was more thorough than that in the conventional treatment group, and the difference was significant (p < .05).

CONCLUSION

Compared with the conventional eyebrow arch-hole approach microsurgery, the 3D surface multi-planar reconstruction image combined 3D printing assisted technology was safer and more effective, and the postoperative recovery was better and the incidence of complications was lower.

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.

Retractorless Surgery for Giant Vestibular Schwannomas via the Retrosigmoid Approach

BACKGROUND

A fixed retractor is routinely used during surgery for vestibular schwannoma to maintain the surgical corridor; however, brain injuries can be caused by use of retractors. The aim of this study was to present strategies for retractorless surgery for giant vestibular schwannomas and compare retractorless surgery with traditional retractor-assisted surgery to illustrate feasibility and potentially superiority of retractorless surgery.

METHODS

Clinical data of 61 patients with giant (≥4 cm diameter) vestibular schwannomas undergoing craniotomy were retrospectively analyzed. Patients were divided into 2 cohorts: 1) 35 patients with traditional retractor surgery performed between June 2016 and July 2017; 2) 26 patients with retractorless surgery performed between June 2016 and July 2018. Duration of operation, intraoperative blood loss, extent of resection, rate of retention of facial nerve function, postoperative brain injury rate, intracranial infection rate, hospitalization time, and grade of facial nerve function were compared between the 2 groups.

RESULTS

The incidence of postoperative brain injury was 3.84% in the retractorless surgery group, which was significantly lower compared with the traditional retractor surgery group (22.86%) (P < 0.05). No significant differences were found regarding the other characteristics compared.

CONCLUSIONS

Through appropriate comprehensive measures, retractorless surgery for giant vestibular schwannomas is an achievable goal. This procedure can reduce the incidence of postoperative brain injury with satisfactory tumor resection.

Experience Using the Pterional Keyhole Approach for the Treatment of Ruptured Intracranial Aneurysms of the Anterior Circulation

BACKGROUND

The pterional keyhole approach is a more recently introduced minimally invasive version of the traditional pterional approach for treating aneurysms of the anterior circulation.

METHODS

In this study, we compared operative parameters and clinical outcomes in patients treated with the pterional keyhole approach and historical controls in whom the traditional pterional approach was used. We reviewer records of 356 patients treated with the pterional keyhole approach between 2009 and 2016, along with those of 301 patients treated via the traditional pterional approach at the same period who served as a control group. The clinical manifestations, surgical details, postoperative complications, and modified Rankin Scale scores in the 2 groups were retrospectively compared.

RESULTS

There were 408 aneurysms in the study group and 362 aneurysms in the control group. In the pterional keyhole group, the total clipping ratio was 93.6%, leaving a remnant/wrapping rate of 6.37%, compared with 93.9% and 6.08%, respectively, in the standard pterional group. In the patients treated via the keyhole approach, the mean bone flap diameter was 4 × 3 cm, mean blood loss was 204 ± 100 mL, mean operation time was 160 ± 57 minutes, and mean length of stay was 8.32 ± 2.72 days, compared with control group parameters of 5 × 6 cm, 284 ± 150 mL, 180 ± 49 minutes, and 11.32 ± 2.48 days, respectively. At a 6-month follow-up, 71.1% had a favorable outcome, 25.8% had a poor outcome, and the mortality was 3.09%, compared with 68.1%, 29.9% and 1.99%, respectively, in the control group.

CONCLUSIONS

The pterional keyhole approach offers shorter operative times, less blood loss, shorter length of stay, and improved cosmesis without sacrificing outcomes compared with traditional pterional craniotomy.

Method for temporal keyhole lobectomies in resection of low- and high-grade gliomas

OBJECTIVE

The purpose of this study was to describe a method of resecting temporal gliomas through a keyhole lobectomy and to share the results of using this technique.

METHODS

The authors performed a retrospective review of data obtained in all patients in whom the senior author performed resection of temporal gliomas between 2012 and 2015. The authors describe their technique for resecting dominant and nondominant gliomas, using both awake and asleep keyhole craniotomy techniques.

RESULTS

Fifty-two patients were included in the study. Twenty-six patients (50%) had not received prior surgery. Seventeen patients (33%) were diagnosed with WHO Grade II/III tumors, and 35 patients (67%) were diagnosed with a glioblastoma. Thirty tumors were left sided (58%). Thirty procedures (58%) were performed while the patient was awake. The median extent of resection was 95%, and at least 90% of the tumor was resected in 35 cases (67%). Five of 49 patients (10%) with clinical follow-up experienced permanent deficits, including 3 patients (6%) with hydrocephalus requiring placement of a ventriculoperitoneal shunt and 2 patients (4%) with weakness. Three patients experienced early postoperative anomia, but no patients had a new speech deficit at clinical follow-up.

CONCLUSIONS

The authors provide their experience using a keyhole lobectomy for resecting temporal gliomas. Their data demonstrate the feasibility of using less invasive techniques to safely and aggressively treat these tumors.

Less is more: Parahippocampal resection or endoscopic assistance in ambient cistern surgery? Qualitative and quantitative assessment of subtemporal approach

The ambient cistern is an arachnoid complex that extends from the crural cistern to lateral border of cerebral colliculi. The subtemporal approach has been recognized as the best access to reach pathologies in the ambient cistern, however many disadvantages exist. The present work aims to analyze quantitatively the area of exposure provided by the subtemporal access. The objective is to evaluate if there are advantages of using the neuroendoscope in conventional subtemporal access when compared to the subtemporal access with resection of the parahippocampal gyrus. A subtemporal approach was performed in six brain hemispheres. Qualitative and quantitative analyses were made. The linear exposition of the vascular structures and the surgical exposure area were evaluated. The linear exposure to the posterior cerebral artery was 5.95 for subtemporal access (ST) and 13.6 for subtemporal access with resection of the parahippocampal gyrus (STh) (p = 0.019). The total exposure area was 104.8 mm² for ST and 210.5 for STh (p = 0.0001). Regarding endoscope assistance the medial area, ST was 81.0 mm², and STend was 176.2 mm² (p = 0.038). For the total area of exposure, we obtained a value of 210.5 mm² for ST and a value of 391.3 mm² for STend (p = 0.041). In conventional subtemporal access, the use of the neuroendoscopes avoids the need for resection of the parahippocampal gyrus for better visualization of the ambient cistern structures.

Monolateral Pterional Keyhole Approaches to Bilateral Cerebral Aneurysms: Anatomy and Clinical Application

OBJECTIVE

To study the anatomy and clinical application of monolateral pterional keyhole approaches for treating bilateral cerebral aneurysms.

METHODS

Twelve formalin-fixed cadaveric heads underwent right pterional keyhole approaches for management of simulative contralateral aneurysms. The length of the contralateral middle cerebral artery (MCA), distal internal carotid artery (DICA), anterior cerebral artery, and ophthalmic segment of the internal carotid artery (OICA) was recorded. The operability of contralateral aneurysms was assessed using a modified numeric grading system. A total of 16 patients (12 patients with ruptured aneurysms) with bilateral cerebral aneurysms undergoing contralateral pterional keyhole approaches were included.

RESULTS

The contralateral A1 segment of the anterior cerebral artery, proximal A2 segment, M1 segment of the MCA, DICA, and OICA was exposed via pterional keyhole approaches. An additional 2 mm of the OICA was exposed after incision of the falciform dural fold was completed. Contralateral aneurysms of the M1 segment (posterior), M2 segment, MCA bifurcation (inferior), A2 segment (lateral), DICA (posterior and lateral), and OICA (superior, inferior, and lateral) could not be fully exposed to perform simulated surgical clipping (operability rate <75%). A total of 36 aneurysms underwent adequate surgical clipping via unilateral pterional keyhole approaches, whereas 1 aneurysm of the A3 segment did not.

CONCLUSIONS

Contralateral aneurysms of the M1 segment (anterior, superior, and inferior), MCA bifurcation (superior and lateral), A1 segment, A2 segment (anterior, posterior, and medial), internal carotid artery bifurcation, DICA (anterior and medial), and OICA (medial) were fully exposed from different angles and surgical maneuvers were performed via pterional keyhole approaches, including in patients presenting with subarachnoid hemorrhage.

Simultaneous Resection of Multiple Metastatic Brain Tumors with Multiple Keyhole Craniotomies

BACKGROUND

The proper management of symptomatic patients with 2 or more brain metastases is not entirely clear, and the surgical outcomes of these patients undergoing multiple simultaneous craniotomies have not been well described. In this article, we describe patient outcomes after simultaneously resecting metastatic lesions through multiple keyhole craniotomies.

METHODS

We conducted a retrospective review of data obtained for all patients undergoing resection of multiple brain metastases in one operation between 2014 and 2016. We describe a technique for resecting multiple metastatic lesions and share the patient outcomes of this operation.

RESULTS

Twenty patients with 46 tumor resections were included in the study. The primary site of metastases for the majority of patients was lung, followed by melanoma, renal, breast, colon, and testes. Nine of 20 (45%) patients had 2 preoperative intracranial lesions, and 11 (55%) had three or more. Karnofsky performance scales were calculated for 14 patients: postoperatively 10 of 14 (71%) scores improved, 2 of 14 (14%) worsened, and 2 of 14 (14%) remained unchanged. After surgery, 9 of 14 (64%) patients were weaned off steroids by 2-month follow-up. The overall median survival time from date of surgery was 10.8 months.

CONCLUSIONS

We present patient outcomes after simultaneously resecting metastatic brain tumors through multiple keyhole craniotomies in symptomatic patients. Our results suggest comparable outcomes and similar surgical risk compared with those undergoing resection of a single brain metastasis. Resection of multiple brain metastases may improve Karnofsky Performance Scale scores in the early postoperative period and allow patients to be weaned from steroids.

Frontal Keyhole Craniotomy for Resection of Low- and High-Grade Gliomas

BACKGROUND

Minimally invasive techniques are increasingly being used to access intra-axial brain lesions.

OBJECTIVE

To describe a method of resecting frontal gliomas through a keyhole craniotomy and share the results with these techniques.

METHODS

We performed a retrospective review of data obtained on all patients undergoing resection of frontal gliomas by the senior author between 2012 and 2015. We describe our technique for resecting dominant and nondominant gliomas utilizing both awake and asleep keyhole craniotomy techniques.

RESULTS

After excluding 1 patient who received a biopsy only, 48 patients were included in the study. Twenty-nine patients (60%) had not received prior surgery. Twenty-six patients (54%) were diagnosed with WHO grade II/III tumors, and 22 patients (46%) were diagnosed with glioblastoma. Twenty-five cases (52%) were performed awake. At least 90% of the tumor was resected in 35 cases (73%). Three of 43 patients with clinical follow-up experienced permanent deficits.

CONCLUSION

We provide our experience in using keyhole craniotomies for resecting frontal gliomas. Our data demonstrate the feasibility of using minimally invasive techniques to safely and aggressively treat these tumors.