Flow diversion for basilar quadrifurcation aneurysms

BACKGROUND

Flow-diverting devices (FDDs), such as the Pipeline Embolization Device, have been gaining traction for treating challenging posterior circulation aneurysms. Few previous studies have focused on using FDDs to treat aneurysms of the basilar quadrifurcation.

METHODS

We retrospectively reviewed the use of FDDs to treat patients with basilar quadrifurcation aneurysms. Patients were assessed for aneurysm type, previous aneurysm treatment, technical success, periprocedural complications, and long-term aneurysm occlusion.

RESULTS

34 patients were assessed; aneurysms of the basilar apex (n=23) or superior cerebellar artery (SCA) (n=7), or both (n=1), and posterior cerebral artery (PCA) (n=3). The mean (SD) largest aneurysm dimension was 8.7 (6.1) mm (range 1.9-30.8 mm). 14 aneurysms were previously surgically clipped or endovascularly coiled. All aneurysms had a saccular morphology. Complete or near-complete occlusion was achieved in 30 of 34 patients (88%) at final angiographic follow-up, a mean (SD) of 6.6 (5.4) months (range 0-19 months) postoperatively. No patient experienced postoperative symptomatic occlusions of the SCA or PCA; 4 patients developed asymptomatic posterior communicating artery occlusions; 28 patients (82%) experienced no complications; whereas 3 (9%) experienced major complications and 3 (9%) experienced minor complications; and 1 patient died as a result of subarachnoid hemorrhage.

CONCLUSION

Flow diversion may be a safe and effective option to treat basilar quadrifurcation aneurysms. Previously treated basilar quadrifurcation aneurysms with recurrence or residual lesion may benefit from additional treatment with an FDD. Further prospective studies should be directed toward validating these findings.

Eloquent noneloquence: redefinition of cortical eloquence based on outcomes of superficial cerebral cavernous malformation resection

OBJECTIVE

Cerebral cavernous malformations (CMs) are pathological lesions that cause discrete cortical disruption with hemorrhage, and their transcortical resections can cause additional iatrogenic disruption. The analysis of microsurgically treated CMs might identify areas of "eloquent noneloquence," or cortex that is associated with unexpected deficits when injured or transgressed.

METHODS

Patients from a consecutive microsurgical series of superficial cerebral CMs who presented to the authors' center over a 13-year period were retrospectively analyzed. Neurological outcomes were measured using the modified Rankin Scale (mRS), and new, permanent neurological or cognitive symptoms not detected by changes in mRS scores were measured as additional functional decline. Patients with multiple lesions and surgical encounters for different lesions within the study interval were represented within the cohort as multiple patient entries. Virtual object models for CMs and approach trajectories to subcortical lesions were merged into a template brain model for subtyping and Quicktome connectomic analyses. Parcellation outputs from the models were analyzed for regional cerebral clustering.

RESULTS

Overall, 362 CMs were resected in 346 patients, and convexity subtypes were the most common (132/362, 36.5%). Relative to the preoperative mRS score, 327 of 362 cases (90.3%) were in patients who improved or remained stable, 35 (9.7%) were in patients whose conditions worsened, and 47 (13.0%) were in patients who had additional functional decline. Machine learning analyses of lesion objects and trajectory cylinder mapping identified 7 hotspots of novel eloquence: supplementary motor area (bilateral), anterior cingulate cortex (bilateral), posterior cingulate cortex (bilateral), anterior insula (left), frontal pole (right), mesial temporal lobe (left), and occipital cortex (right).

CONCLUSIONS

Transgyral and transsulcal resections that circumvent areas of traditional eloquence and navigate areas of presumed noneloquence may nonetheless result in unfavorable outcomes, demonstrating that brain long considered by neurosurgeons to be noneloquent may be eloquent. Eloquent hotspots within multiple large-scale networks redefine the neurosurgical concept of eloquence and call for more refined dissection techniques that maximize transsulcal dissection, intracapsular resection, and tissue preservation. Human connectomics, awareness of brain networks, and prioritization of cognitive outcomes require that we update our concept of cortical eloquence and incorporate this information into our surgical strategies.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Recurrent Glioblastoma and Radiation Necrosis: A Single-Surgeon Case Series

OBJECTIVE

To evaluate long-term clinical outcomes among patients treated with laser interstitial thermal therapy (LITT) for predicted recurrent glioblastoma (rGBM).

METHODS

Patients with rGBM treated by LITT by a single surgeon (2013-2020) were evaluated for progression-free survival (PFS), overall survival (OS), and OS after LITT.

RESULTS

Forty-nine patients (33 men, 16 women; mean [SD] age at diagnosis, 58.7 [12.5] years) were evaluated. Among patients with genetic data, 6 of 34 (18%) had IDH-1 R132 mutations, and 7 of 21 (33%) had MGMT methylation. Patients underwent LITT at a mean (SD) of 23.8 (23.8) months after original diagnosis. Twenty of 49 (40%) had previously undergone stereotactic radiosurgery, 37 (75%) had undergone intensity-modulated radiation therapy, and 49 (100%) had undergone chemotherapy. Patients had undergone a mean of 1.2 (0.7) previous resections before LITT. Mean preoperative enhancing and T2 FLAIR volumes were 13.1 (12.8) cm3 and 35.0 (32.8) cm3, respectively. Intraoperative biopsies confirmed rGBM in 31 patients (63%) and radiation necrosis in 18 patients (37%). Six perioperative complications occurred: 3 (6%) cases of worsening aphasia, 1 (2%) seizure, 1 (2%) epidural hematoma, and 1 (2%) intraparenchymal hemorrhage. For the rGBM group, median PFS was 2.0 (IQR, 4.0) months, median OS was 20.0 (IQR, 29.5) months, and median OS after LITT was 6.0 (IQR, 10.5) months. For the radiation necrosis group, median PFS was 4.0 (IQR, 4.5) months, median OS was 37.0 (IQR, 58.0) months, and median OS after LITT was 8.0 (IQR, 23.5) months.

CONCLUSIONS

In a diverse rGBM cohort, LITT was associated with a short duration of posttreatment PFS.

A taxonomy for superficial cerebral cavernous malformations: subtypes of cortical and subcortical lesions

OBJECTIVE

A taxonomy for superficial cerebral cavernous malformations (CMs), those based cortically in gyral gray matter or subcortically in underlying white matter, is proposed to build on the comprehensive, systematic characterization of CMs in the entire brain.

METHODS

Patients with superficial cerebral CMs were retrospectively analyzed from a consecutive surgical series between November 2008 and June 2021 at the authors' center. Superficial cerebral CMs were categorized into 4 subtypes based on their cortical location or, if subcortical, proximity to the nearest cerebral surface: convexity, medial, basal, and sylvian. Lobar location was also included for subtyping: frontal, temporal, parietal, and occipital.

RESULTS

A total of 362 CMs were resected in 346 patients. CM subtypes were as follows: 132 (36.5%) convexity, 78 (21.5%) medial, 72 (19.9%) basal, and 80 (22.1%) sylvian. Frontal CMs were most common (155 [42.8%]), followed by parietal (89 [24.6%]), temporal (87 [24.0%]), and occipital (31 [8.6%]). Of all CMs, 302 (83.4%) were cortical and 60 (16.6%) were subcortical. The mean subcortical depth of deep lesions was 2.97 cm, and the mean lesion volume was 4.68 cm3. Overall, 228 lesions (63.0%) were resected through a transgyral approach, and 134 (37.0%) were resected through a transsulcal approach. Good outcomes (modified Rankin Scale [mRS] score ≤ 2) were observed in 314 patients (86.7%) and poor outcomes (mRS score > 2) in 25 patients (6.9%), and 23 patients (6.4%) were lost to late follow-up (mean follow-up duration 11.5 months). Relative outcomes were good (unchanged or improved mRS score) in 327 patients (90.3%) and poor (worse or died) in 35 patients (9.7%).

CONCLUSIONS

Superficial cerebral CMs were resected through a gyrus or sulcus to open the subarachnoid dissection corridors, traversing the full extent of sulci to deepen the approach and minimize tissue transgression. Transgyral dissection avoids associated arteries but is inherently transgressive, whereas transsulcal dissection preserves cortical tissue and may reduce morbidity. Superficial cerebral CMs occupy the largest territory of the 7 types, and the size and surface complexity of the cerebrum make taxonomic subtyping valuable for clear anatomical description.

A system of anatomical triangles defining dissection routes to brainstem cavernous malformations: definitions and application to a cohort of 183 patients

OBJECTIVE

Anatomical triangles defined by intersecting neurovascular structures delineate surgical routes to pathological targets and guide neurosurgeons during dissection steps. Collections or systems of anatomical triangles have been integrated into skull base surgery to help surgeons navigate complex regions such as the cavernous sinus. The authors present a system of triangles specifically intended for resection of brainstem cavernous malformations (BSCMs). This system of triangles is complementary to the authors' BSCM taxonomy that defines dissection routes to these lesions.

METHODS

The anatomical triangle through which a BSCM was resected microsurgically was determined for the patients treated during a 23-year period who had both brain MRI and intraoperative photographs or videos available for review.

RESULTS

Of 183 patients who met the inclusion criteria, 50 had midbrain lesions (27%), 102 had pontine lesions (56%), and 31 had medullary lesions (17%). The craniotomies used to resect these BSCMs included the extended retrosigmoid (66 [36.1%]), midline suboccipital (46 [25.1%]), far lateral (30 [16.4%]), pterional/orbitozygomatic (17 [9.3%]), torcular (8 [4.4%]), and lateral suboccipital (8 [4.4%]) approaches. The anatomical triangles through which the BSCMs were most frequently resected were the interlobular (37 [20.2%]), vallecular (32 [17.5%]), vagoaccessory (30 [16.4%]), supracerebellar-infratrochlear (16 [8.7%]), subtonsillar (14 [7.7%]), oculomotor-tentorial (11 [6.0%]), infragalenic (8 [4.4%]), and supracerebellar-supratrochlear (8 [4.4%]) triangles. New but infrequently used triangles included the vertebrobasilar junctional (1 [0.5%]), supratrigeminal (3 [1.6%]), and infratrigeminal (5 [2.7%]) triangles. Overall, 15 BSCM subtypes were exposed through 6 craniotomies, and the approach was redirected to the BSCM by one of the 14 triangles paired with the BSCM subtype.

CONCLUSIONS

A system of BSCM triangles, including 9 newly defined triangles, was introduced to guide dissection to these lesions. The use of an anatomical triangle better defines the pathway taken through the craniotomy to the lesion and refines the conceptualization of surgical approaches. The triangle concept and the BSCM triangle system increase the precision of dissection through subarachnoid corridors, enhance microsurgical execution, and potentially improve patient outcomes.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Management of Low-Grade Gliomas and Radiation Necrosis: A Single-Institution Case Series

BACKGROUND

Laser interstitial thermal therapy (LITT) has emerged as a minimally invasive treatment modality for ablation of low-grade glioma (LGG) and radiation necrosis (RN).

OBJECTIVE

To evaluate the efficacy, safety, and survival outcomes of patients with radiographically presumed recurrent or newly diagnosed LGG and RN treated with LITT.

METHODS

The neuro-oncological database of a quaternary center was reviewed for all patients who underwent LITT for management of LGG between 1 January 2013 and 31 December 2020. Clinical data including demographics, lesion characteristics, and clinical and radiographic outcomes were collected. Kaplan-Meier analyses comprised overall survival (OS) and progression-free survival (PFS).

RESULTS

Nine patients (7 men, 2 women; mean [SD] age 50 [16] years) were included. Patients underwent LITT at a mean (SD) of 11.6 (8.5) years after diagnosis. Two (22%) patients had new lesions on radiographic imaging without prior treatment. In the other 7 patients, all (78%) had surgical resection, 6 (67%) had intensity-modulated radiation therapy and chemotherapy, respectively, and 4 (44%) had stereotactic radiosurgery. Two (22%) patients had lesions that were wild-type IDH1 status. Volumetric assessment of preoperative T1-weighted contrast-enhancing and T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences yielded mean (SD) lesion volumes of 4.1 (6.5) cm³ and 26.7 (27.9) cm³, respectively. Three (33%) patients had evidence of radiographic progression after LITT. The pooled median (IQR) PFS for the cohort was 52 (56) months, median (IQR) OS after diagnosis was 183 (72) months, and median (IQR) OS after LITT was 52 (60) months. At the time of the study, 2 (22%) patients were deceased.

CONCLUSIONS

LITT is a safe and effective treatment option for management of LGG and RN, however, there may be increased risk of permanent complications with treatment of deep-seated subcortical lesions.

Barrow Innovation Center: A 5-Year Update and Future Direction

OBJECTIVE

The rich history of neurosurgical innovation served as a model for the Barrow Innovation Center's establishment in 2016. The center's accomplishments are summarized in hopes of fostering the development of similar centers and initiatives within the neurosurgical and broader medical community.

METHODS

A retrospective review (January 2016-July 2021) of patent filings, project proposals, and funding history was used to generate the data presented in this operational review.

RESULTS

Through the 5-year period of analysis, 55 prior art searches were conducted on new patentable ideas. A total of 87 provisional patents, 25 Patent Cooperation Treaty applications, and 48 national stage filings were submitted. In partnership with Arizona State University, the University of Arizona, California Polytechnic State University, and Texas A&M University, a total of 27 multidisciplinary projects were conducted with input from multispecialty engineers and scientists. These efforts translated into 1 startup company and 2 licensed patents to commercial companies, with most remaining ideas and project efforts awaiting interest from industry.

CONCLUSIONS

The multidisciplinary collaborative environment embodied by the Barrow Innovation Center has revolutionized the innovative and entrepreneurial environment of its home institution and enabled neurosurgical residents to get a unique educational experience within the realm of innovation. The bottleneck within the workflow of ideas from conception to commercialization appears to be the establishment of commercial partners; therefore, future efforts within the center will be to establish a panel of industry partnerships to enhance the exposure of ideas to interested companies.

Neurosurgery Subspecialty Practice During a Pandemic: A Multicenter Analysis of Operative Practice in 7 U.S. Neurosurgery Departments During Coronavirus Disease 2019

OBJECTIVE

Changes to neurosurgical practices during the coronavirus disease 2019 (COVID-19) pandemic have not been thoroughly analyzed. We report the effects of operative restrictions imposed under variable local COVID-19 infection rates and health care policies using a retrospective multicenter cohort study and highlight shifts in operative volumes and subspecialty practice.

METHODS

Seven academic neurosurgery departments' neurosurgical case logs were collected; procedures in April 2020 (COVID-19 surge) and April 2019 (historical control) were analyzed overall and by 6 subspecialties. Patient acuity, surgical scheduling policies, and local surge levels were assessed.

RESULTS

Operative volume during the COVID-19 surge decreased 58.5% from the previous year (602 vs. 1449, P = 0.001). COVID-19 infection rates within departments' counties correlated with decreased operative volume (r = 0.695, P = 0.04) and increased patient categorical acuity (P = 0.001). Spine procedure volume decreased by 63.9% (220 vs. 609, P = 0.002), for a significantly smaller proportion of overall practice during the COVID-19 surge (36.5%) versus the control period (42.0%) (P = 0.02). Vascular volume decreased by 39.5% (72 vs. 119, P = 0.01) but increased as a percentage of caseload (8.2% in 2019 vs. 12.0% in 2020, P = 0.04). Neuro-oncology procedure volume decreased by 45.5% (174 vs. 318, P = 0.04) but maintained a consistent proportion of all neurosurgeries (28.9% in 2020 vs. 21.9% in 2019, P = 0.09). Functional neurosurgery volume, which declined by 81.4% (41 vs. 220, P = 0.008), represented only 6.8% of cases during the pandemic versus 15.2% in 2019 (P = 0.02).

CONCLUSIONS

Operative restrictions during the COVID-19 surge led to distinct shifts in neurosurgical practice, and local infective burden played a significant role in operative volume and patient acuity.

Ketogenic Metabolic Therapy for Glioma

Purpose: This study describes a retrospective case series of patients with glioma who received ketogenic metabolic therapy through dietary adherence and intermittent fasting.

Methods: A retrospective chart review of a single surgeon’s clinic records was performed to identify patients who maintained nutritional ketosis for at least four months between January 2015 and October 2020.

Results: Sixteen patients who met the inclusion criteria constituted a heterogeneous population of patients with diagnoses including eight World Health Organization (WHO) grade IV gliomas (seven glioblastoma, one gliosarcoma), seven WHO grade III gliomas (three oligodendroglioma, four astrocytoma), and one WHO grade II oligodendroglioma. IDH1 mutation status was present for 12 patients, and MGMT methylation status was present for eight patients. The mean (standard deviation [SD]) duration of ketogenic metabolic therapy was 20.6 (13.8) months. The Response Assessment in Neuro-oncology Criteria was applied during the ketogenic metabolic therapy interval, indicating a complete response in eight patients and partial response in eight patients. The mean (SD) progression-free survival while patients maintained ketogenic metabolic therapy was 20.0 (14.4) months.

Conclusion: Ketogenic metabolic therapy appears to convey a survival advantage within this patient series, which highlights the possibility that this therapy, when strictly applied, can augment the standard of care. Further exploration of this modality in a prospective series is warranted to formally explore this therapy.

Unique Presentation and Novel Surgical Approach to a Transcribriform Penetrating Head Injury Caused by a Nail Gun

A penetrating head injury caused by a nail gun is an infrequent clinically diverse condition that varies in severity by the neurovascular structures involved. The authors present the case of a patient whose frontal lobe was pierced by a nail that entered via a transnasal transcribriform trajectory without causing vascular injury or intracranial hemorrhage; the man was unaware of the nail’s presence and presented with headache five days after the incident. The nail was extracted using a bifrontal craniotomy for direct visualization and for defect repair of the skull base combined with endoscopic endonasal extraction of the nail.

Trigeminal Rhizotomy Using Gyroscopic Radiosurgery: A Case Report

Characterized by intense, episodic lancinating pain within the distribution of the trigeminal nerve, trigeminal neuralgia (TN) is the most common craniofacial pain syndrome. Failure of medical management requires the consideration of interventional procedures. Stereotactic radiosurgery (SRS) is one of the more commonly used surgical options. Herein, we report the first published case of a patient with TN treated in the ZAP-X (San Carlos, CA: ZAP Surgical Systems, Inc.) gyroscopic radiosurgery system. This 59-year-old man with multiple sclerosis and recurrent intractable left idiopathic TN following previous SRS was retreated in the Zap-X system using 100 isocentric 5 mm beams to a dose of 7500 cGy. At a three-month follow-up, the patient reported a 45% decrease in his visual analogue scale (VAS) and a reduced need for medication. Albeit preliminary, this initial experience highlights the feasibility of a self-shielded, cobalt-free, device for radiosurgically treating TN.

Avoiding the Radial Paradox: Neuroendovascular Femoral Access Outcomes After Radial Access Adoption

BACKGROUND

Transradial access (TRA) for neuroendovascular procedures is increasing in prevalence. The safety benefits of TRA at a patient level may be offset at a population level by a paradoxical increase in transfemoral access (TFA) vascular access site complications (VASCs), the so-called "radial paradox."

OBJECTIVE

To study the effect of TRA adoption on TFA performance and outcomes in neuroendovascular procedures.

METHODS

Data were collected for all procedures performed over a 10-mo period after radial adoption at a single center.

RESULTS

Over the study period, 1084 procedures were performed, including 719 (66.3%) with an intent to treat by TRA and 365 (33.7%) with an intent to treat by TFA. Thirty-two cases (4.4%) crossed over from TRA to TFA, and 2 cases (0.5%) crossed over from TFA to TRA. TFA was performed in older patients (mean [standard deviation] TFA, 63 [15] vs TRA, 56 [16] years) using larger sheath sizes (≥7 French; TFA, 56.2% vs TRA, 2.3%) ( P < .001 for both comparisons). Overall, 29 VASCs occurred (2.7%), including 27 minor (TFA, 4.6% [18/395] vs TRA, 1.3% [9/689], P = .002) and 2 major (TFA, 0.3% [1/395] vs TRA, 0.1% [1/689], P > .99) complications. Independent predictors of VASC included TFA (OR 2.8, 95% confidence interval [CI] 1.1-7.4) and use of dual antiplatelet therapy (OR 4.2, 95% CI 1.6-11.1).

CONCLUSION

TFA remains an important access route, despite a predominantly radial paradigm, and is disproportionately used in patients at increased risk for VASCs. TFA proficiency may still be achieved in predominantly radial practices without an increase in femoral complications.

Resection of Brainstem Cavernous Malformations: Pearls and Pitfalls for Minimizing Complications

BACKGROUND

Surgical management of brainstem cavernous malformations (CMs) is a controversial topic in the field of neurosurgery. These lesions have a propensity to hemorrhage, thereby disrupting surrounding brainstem eloquence.

METHODS

This article provides the personal reflections of the senior author and a narrative literature review on resection of brainstem CMs.

RESULTS

Here we discuss the indications for microsurgery, microsurgical techniques and nuances, and perioperative management considerations necessary to minimize complications during resection of brainstem CMs, which are lesions of venous origin.

CONCLUSIONS

The natural history of the lesion, risk of future hemorrhage, and potential for symptom resolution should be carefully considered when planning to resect brainstem CMs. Nuanced microsurgical techniques with minimal disruption of normal tissues provide the best chance of satisfactory outcomes.

Resection of Brainstem Arteriovenous Malformations: Pearls and Pitfalls for Minimizing Complications

BACKGROUND

The decision-making process surrounding resection of arteriovenous malformations (AVMs) in proximity to vital brainstem structures is a complex topic. Intricate vasculature in the setting of exquisite brainstem eloquence creates a high-risk operative landscape with the potential for devastating complications. Effective resections are driven by mastery of the relevant operative anatomy, preservation of pertinent vasculature, and technical experience and acumen.

METHODS

This article provides a narrative literature review on the resection of brainstem AVMs.

RESULTS

Operative anatomy and approaches to AVMs of the midbrain (anterior/posterior), pons (anterior/lateral), and medulla (anterior/lateral) are discussed herein, with a focus on pearls and pitfalls for minimizing complications during resection.

CONCLUSIONS

Careful consideration of the patient's clinical background, the natural history of the lesion, and expertise of the treating surgeon are paramount for improving the natural course of brainstem AVMs.

Endovascular therapy versus microsurgical clipping of unruptured wide-neck aneurysms: a prospective multicenter study with propensity score analysis

OBJECTIVE

Numerous techniques have been developed to treat wide-neck aneurysms (WNAs), each with different safety and efficacy profiles. Few studies have compared endovascular therapy (EVT) with microsurgery (MS). The authors' objective was to perform a prospective multicenter study of a WNA registry using rigorous outcome assessments and to compare EVT and MS using propensity score analysis (PSA).

METHODS

Unruptured, saccular, not previously treated WNAs were included. WNA was defined as an aneurysm with a neck width ≥ 4 mm or a dome-to-neck ratio (DTNR) < 2. The primary outcome was modified Rankin Scale (mRS) score at 1 year after treatment (good outcome was defined as mRS score 0-2), as assessed by blinded research nurses and compared with PSA. Angiographic outcome was assessed using the Raymond scale with core laboratory review (adequate occlusion was defined as Raymond scale score 1-2).

RESULTS

The analysis included 224 unruptured aneurysms in the EVT cohort (n = 140) and MS cohort (n = 84). There were no differences in baseline demographic characteristics, such as proportion of patients with good baseline mRS score (94.3% of the EVT cohort vs 94.0% of the MS cohort, p = 0.941). WNA inclusion criteria were similar between cohorts, with the most common being both neck width ≥ 4 mm and DTNR < 2 (50.7% of the EVT cohort vs 50.0% of the MS cohort, p = 0.228). More paraclinoid (32.1% vs 9.5%) and basilar tip (7.1% vs 3.6%) aneurysms were treated with EVT, whereas more middle cerebral artery (13.6% vs 42.9%) and pericallosal (1.4% vs 4.8%) aneurysms were treated with MS (p < 0.001). EVT aneurysms were slightly larger (p = 0.040), and MS aneurysms had a slightly lower mean DTNR (1.4 for the EVT cohort vs 1.3 for the MS cohort, p = 0.010). Within the EVT cohort, 9.3% of patients underwent stand-alone coiling, 17.1% balloon-assisted coiling, 34.3% stent-assisted coiling, 37.1% flow diversion, and 2.1% PulseRider-assisted coiling. Neurological morbidity secondary to a procedural complication was more common in the MS cohort (10.3% vs 1.4%, p = 0.003). One-year mRS scores were assessed for 218 patients (97.3%), and no significantly increased risk of poor clinical outcome was found for the MS cohort (OR 2.17, 95% CI 0.84-5.60, p = 0.110). In an unadjusted direct comparison, more patients in the EVT cohort achieved a good clinical outcome at 1 year (93.4% vs 84.1%, p = 0.048). Final adequate angiographic outcome was superior in the MS cohort (97.6% of the MS cohort vs 86.5% of the EVT cohort, p = 0.007).

CONCLUSIONS

Although the treatments for unruptured WNA had similar clinical outcomes according to PSA, there were fewer complications and superior clinical outcome in the EVT cohort and superior angiographic outcomes in the MS cohort according to the unadjusted analysis. These results may be considered when selecting treatment modalities for patients with unruptured WNAs.

ZAP-X Gyroscopic Radiosurgery System: A Preliminary Analysis of Clinical Applications within a Retrospective Case Series

INTRODUCTION

The ZAP-X Gyroscopic Radiosurgery system (ZAP Surgical Systems, Inc., San Carlos, CA, USA) is a novel high-dose targeted stereotactic radiosurgery platform for outpatient use that includes self-shielding, X-ray image guidance, and the capacity to aim the radiation beam gyroscopically at an intracranial lesion using 5 independent degrees of freedom. The ZAP-X Gyroscopic Radiosurgery system accomplishes these actions while meeting widely accepted standards for dose gradient and accuracy. This retrospective study examined data of patients treated with gyroscopic radiosurgery (GRS) to document clinical outcomes.

METHODS

Medical records of all outpatients treated with GRS over a 20-month period from January 2019 to August 2020 were searched to extract relevant details, including follow-up data until August 2021 (32-month study interval). Patients with <6 months of radiographical follow-up data were excluded unless death occurred. Data collection included pretreatment clinical history, pathological diagnosis, radiographical features, treatment parameters, and long-term clinical and radiographical follow-up.

RESULTS

Sixty-eight patients received outpatient treatment with GRS during the 20-month treatment interval, with 59 patients remaining after exclusion for the minimum follow-up threshold, with a mean (standard deviation [SD]) fractionation of 1.85 (1.63). Eighty-two lesions were treated across a very heterogeneous patient population, including meningiomas (42.4%), metastases (39.0%), gliomas (6.8%), schwannomas (1.7%), and pituitary tumor (1.7%). Mean (SD) radiographical follow-up data (14.7 [6.60] months) were available for 56 patients. During that interval, 13 treated lesions in 13 patients (15.9%) demonstrated progression, 9 of which were stable during the initial posttreatment imaging surveillance period. Mean lesion volume was stable from pretreatment (2.54 cm3 [4.37 cm3]) to most recent follow-up (2.80 cm3 [8.20 cm3]) (t [79] = -0.310; p = 0.76). Minor adverse clinical events were noted in 3 (5.1%) of the 59 patients during the posttreatment phase that may have been related to the treatment. Ten (16.9%) patients died within the 32-month study interval.

DISCUSSION/CONCLUSION

This preliminary assessment of the first series of patients treated with the Zap-X Gyroscopic Radiosurgery system documents its overall feasibility in clinical applications. Although the duration of follow-up was brief, GRS appeared to be both safe and effective. Additional analysis, with an ongoing prospective registry, is underway.

Endovascular Therapy Versus Microsurgical Clipping of Ruptured Wide Neck Aneurysms (EVERRUN Registry): a multicenter, prospective propensity score analysis

OBJECTIVE

Randomized controlled trials have demonstrated the superiority of endovascular therapy (EVT) compared to microsurgery (MS) for ruptured aneurysms suitable for treatment or when therapy is broadly offered to all presenting aneurysms; however, wide neck aneurysms (WNAs) are a challenging subset that require more advanced techniques and warrant further investigation. Herein, the authors sought to investigate a prospective, multicenter WNA registry using rigorous outcome assessments and compare EVT and MS using propensity score analysis (PSA).

METHODS

Untreated, ruptured, saccular WNAs were included in the analysis. A WNA was defined as having a neck ≥ 4 mm or a dome/neck ratio (DNR) < 2. The primary outcome was the modified Rankin Scale (mRS) score at 1 year posttreatment, as assessed by blinded research nurses (good outcome: mRS scores 0-2) and compared using PSA.

RESULTS

The analysis included 87 ruptured aneurysms: 55 in the EVT cohort and 32 in the MS cohort. Demographics were similar in the two cohorts, including Hunt and Hess grade (p = 0.144) and modified Fisher grade (p = 0.475). WNA type inclusion criteria were similar in the two cohorts, with the most common type having a DNR < 2 (EVT 60.0% vs MS 62.5%). More anterior communicating artery aneurysms (27.3% vs 18.8%) and posterior circulation aneurysms (18.2% vs 0.0%) were treated with EVT, whereas more middle cerebral artery aneurysms were treated with MS (34.4% vs 18.2%, p = 0.025). Within the EVT cohort, 43.6% underwent stand-alone coiling, 50.9% balloon-assisted coiling, 3.6% stent-assisted coiling, and 1.8% flow diversion. The 1-year mRS score was assessed in 81 patients (93.1%), and the primary outcome demonstrated no increased risk for a poor outcome with MS compared to EVT (OR 0.43, 95% CI 0.13-1.45, p = 0.177). The durability of MS was higher, as evidenced by retreatment rates of 12.7% and 0% for EVT and MS, respectively (p = 0.04).

CONCLUSIONS

EVT and MS had similar clinical outcomes at 1 year following ruptured WNA treatment. Because of their challenging anatomy, WNAs may represent a population in which EVT's previously demonstrated superiority for ruptured aneurysm treatment is less relevant. Further investigation into the treatment of ruptured WNAs is warranted.

Perioperative Complication Profile of Skull Base Meningioma Resection in Older versus Younger Adult Patients

Objectives To better understand the risk-benefit profile of skull base meningioma resection in older patients, we compared perioperative complications among older and younger patients.

Design Present study is based on retrospective outcomes comparison.

Setting The study was conducted at a single neurosurgery institute at a quaternary center.

Participants All older (age ≥ 65 years) and younger (<65 years) adult patients treated with World Health Organization grade 1 skull base meningiomas (2008–2017).

Main Outcome Measures Perioperative complications and patient functional status are the primary outcomes of this study.

Results The analysis included 287 patients, 102 older and 185 younger, with a mean (standard deviation [SD]) age of 72 (5) years and 51 (9) years (p < 0.01). Older patients were more likely to have hypertension (p < 0.01) and type 2 diabetes mellitus (p = 0.01) but other patient and tumor factors did not differ (p ≥ 0.14). Postoperative medical complications were not significantly different in older versus younger patients (10.8 [11/102] vs. 4.3% [8/185]; p = 0.06) nor were postoperative surgical complications (13.7 [14/102] vs. 10.8% [20/185]; p = 0.46). Following anterior skull base meningioma resection, diabetes insipidus (DI) was more common in older versus younger patients (14 [5/37] vs. 2% [1/64]; p = 0.01). Among older patients, a decreasing preoperative Karnofsky performance status score independently predicted perioperative complications by logistic regression analysis (p = 0.02). Permanent neurologic deficits were not significantly different in older versus younger patients (12.7 [13/102] vs. 10.3% [19/185]; p = 0.52).

Conclusion The overall perioperative complication profile of older and younger patients was similar after skull base meningioma resection. Older patients were more likely to experience DI after anterior skull base meningioma resection. Decreasing functional status in older patients predicted perioperative complications.

Residual Tumor Volume and Tumor Progression after Subtotal Resection and Observation of WHO Grade I Skull Base Meningiomas

Objective This study investigated the impact of residual tumor volume (RTV) on tumor progression after subtotal resection and observation of WHO grade I skull base meningiomas.

Study Design This study is a retrospective volumetric analysis.

Setting This study was conducted at a single institution.

Participants Patients who underwent subtotal resection of a WHO grade I skull base meningioma and postsurgical observation (July 1, 2007–July 1, 2017).

Main Outcome Measure The main outcome was radiographic tumor progression.

Results Sixty patients with residual skull base meningiomas were analyzed. The median (interquartile range) RTV was 1.3 (5.3) cm3. Tumor progression occurred in 23 patients (38.3%) at a mean duration of 28.6 months postsurgery. The 1-, 3-, and 5-year actuarial progression-free survival (PFS) rates were 98.3, 58.6, and 48.7%, respectively. The Cox multivariate analysis identified increasing RTV (p = 0.01) and history of more than 1 previous surgery (p = 0.03) as independent predictors of tumor progression. In a Kaplan–Meier analysis for PFS, the RTV threshold of 3 cm3 maximized log-rank testing significance between groups of patients dichotomized at 0.5 cm3 thresholds (p < 0.01). The 3-year actuarial PFS rates for meningiomas with RTV ≤3 cm3 and >3 cm3 were 76.2 and 32.1%, respectively. When RTV >3 cm3 was entered as a covariate in the Cox model, it was the only factor independently associated with tumor progression (p < 0.01).

Conclusion RTV was associated with tumor progression after subtotal resection of WHO grade I skull base meningioma in this cohort. An RTV threshold of 3 cm3 was identified that minimized progression of the residual tumor when gross total resection was not safe or feasible.

Microsurgical Anatomy of the Endoscopy-Assisted Retrosigmoid Intradural Suprameatal Approach to the Meckel's Cave

BACKGROUND

Understanding the microsurgical anatomical features of the endoscopy-assisted retrosigmoid intradural suprameatal approach (RISA) is critical for surgeons treating petroclival tumors or lesions in the cerebellopontine region that extend into Meckel's cave.

OBJECTIVE

To evaluate increased exposure for Meckel's cave in the RISA and assess the surgical landmarks for this approach.

METHODS

A standard retrosigmoid craniotomy to the cerebellopontine region was performed in 4 cadaveric specimens (8 hemispheres) with microscope-assisted endoscopy. The length and depth of the drilling region from the suprameatal tubercle to the petrous apex were analyzed. After opening Meckel's cave and mobilizing the trigeminal root completely, the landmarks for this approach were investigated.

RESULTS

The endoscopy-assisted RISA facilitates mobilization of the trigeminal root and enhances surgical exposure in the region of Meckel's cave and the petrous apex with increases of 10.1 ± 1.3 mm in depth, 21.4 ± 3.2 mm in length, and 6.4 ± 0.6 mm in height. The posterior and superior semicircular canals, internal auditory canal, superior petrous sinus, and internal carotid artery (petrous segment) served as important landmarks for this approach. One case illustration is presented to describe the application of this approach.

CONCLUSION

The RISA is suitable mainly for lesions in the posterior fossa that extend into Meckel's cave. The endoscopy-assisted reach optimizes accessibility to the petrous apex region, obviates the need for extensive drilling, and decreases the risk of internal carotid artery injury. Better realization and recognition of microsurgical landmarks and parameters of this approach are crucial for successful outcomes.

Single-Surgeon in Vivo Experience with the Zeiss QEVO Microinspection Tool: An Analysis of Its Use for Extending the Reach of Operative Visualization

The operating microscope is a foundational tool in modern neurosurgery. Operating microscopes serve increasingly as the lynchpin for highly sophisticated visualization platforms incorporating many complementary technologies. The Zeiss QEVO microinspection tool is a 45-degree viewing endoscopic instrument integrated into the Zeiss KINEVO 900 operating microscope (Carl Zeiss AG, Oberkochen, Germany). The QEVO tool enables surgeons to "look around the corners" of the surgical field to optimize visualization within tight operative corridors. In this article, we document our experience using the QEVO microinspection tool in a series of complex cranial neurosurgery procedures. This report focuses on the handling, visualization, and overall utility of the QEVO tool for achieving optimal visualization in deep cranial corridors.

Far-Lateral Approach for Medullary Cavernous Malformation: 2-Dimensional Operative Video

Medullary cavernous malformations are the rarest subtype of brainstem cavernous malformation and are associated with a high degree of morbidity. Selection of surgical candidates is critical, and cases are most favorable when the cavernous malformation abuts the surface of the brainstem. This limits the amount of native tissue transgressed during the resection. This patient had a large cavernous malformation within the caudal medulla eccentric. A right-sided paramedian far-lateral approach was used to access the brainstem. The cavernous malformation was readily apparent along the medullary surface and was dissected away in its entirety. Postoperative imaging confirmed complete resection. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Extradural Clinoidectomy: An Efficient Technique for Expanding the Operative Corridor Toward the Central Skull Base

Extradural anterior clinoidectomy is an important tool for neurovascular and skull base surgery. This technique is cardinal for expanding access to the proximal carotid artery, optic nerve, sella, and the central skull base. The goal of anterior clinoidectomy is to reveal the more proximal ophthalmic and clinoidal segments of the internal carotid artery (ICA) while skeletonizing the proximal optic nerve. This maneuver expands the opticocarotid and carotid-oculomotor windows and therefore the operative corridor to the interpeduncular cisterns; both the carotid artery and optic nerve are partially untethered or liberated and can be more safely mobilized.

Microsurgical Resection of Brainstem Arteriovenous Malformation: 2-Dimensional Operative Video

Brainstem arteriovenous malformations (AVMs) are rare lesions (2%-6% of all intracranial AVMs) that are surgically challenging because of the high eloquence of the brainstem, including dense fiber tracts, cranial nerves, and multiple vital cerebrovascular structures. All these lesions possess eloquence and deep venous drainage, making them innately Spetlzer-Martin grade III or above. This patient had a large midbrain AVM with a complex clinical course beginning with ventriculoperitoneal shunting due to mass effect; the patient experienced 4 hemorrhages, underwent radiation treatment, and finally underwent surgical resection. The surgical approach involved a large torcular craniotomy exposing all posterior sinuses at the confluence. The vein of Galen was exposed and carried deeply to permit ambient cistern opening and relaxation of the cerebellum. Because of earlier radiation therapy, the vessels had undergone hyalinosis, which resulted in difficult manipulation of the nidus but did permit excellent coagulation of the vessels. The complete nidus was removed, as confirmed on postoperative angiography. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

The Extended Pterional Craniotomy: A Contemporary and Balanced Approach

Pterional craniotomy is the workhorse approach among cranial operative corridors. It is a highly flexible skull base approach that affords excellent exposure of the anterior cranial fossa, the circle of Willis, and the interpeduncular region. Its strategic use via dynamic retraction can obviate the need to use a more extensive skull base route, such as orbitozygomatic osteotomy, in select cases. The focus of the surgeon should be reaching the surgical target effectively while minimizing disruption of normal anatomy. In other words, the focus should be less on "how to get there" and more on "what to do when you are there." This multimedia presentation summarizes an efficient execution of this route and its expansion and demonstrates the surgical corridor via 3-dimensional virtual reality models.

The Neurosurgical Atlas: advancing neurosurgical education in the digital age

OBJECTIVE

The advent of the internet and the popularity of e-learning resources has promoted a shift in medical and surgical education today. The Neurosurgical Atlas has sought to capitalize on this shift by providing easily accessible video and online education to its users on an international scale. The rising popularity of social media has provided new avenues for expanding that global reach, and the Atlas has sought to do just that. In this study, the authors analyzed user demographics and web traffic patterns to quantify the international reach of the Atlas and examined the potential impact of social media platforms on the expansion of that reach.

METHODS

Twitter, Facebook, and Instagram metrics were extracted using each respective service's analytics tool from the date of their creation through October 2019. Google Analytics was used to extract website traffic data from September 2018 to September 2019 and app data from January 2019 to October 2019. The metrics extracted included the number of platform users/followers, user demographic information, percentage of new versus returning visitors, and a number of platform-specific values.

RESULTS

Since the authors' previous publication in 2017, annual website viewership has more than doubled to greater than 500,000 viewing sessions in the past year alone; international users accounted for more than 60% of the visits. The Atlas Twitter account, established in August 2012, has more than 12,000 followers, primarily hailing from the United States, the United Kingdom, Canada, and Saudi Arabia. The Atlas Facebook account, established in 2013, has just over 13,000 followers, primarily from India, Egypt, and Mexico. The Atlas Instagram account (established most recently, in December 2018) has more than 16,000 followers and the highest percentage (31%) of younger users (aged 18-24 years). The Atlas app was officially launched in May 2019, largely via promotion on the Atlas social media platforms, and has since recorded more than 60,000 viewing sessions, 80% of which were from users outside the United States.

CONCLUSIONS

The Neurosurgical Atlas has attempted to leverage the many e-learning resources at its disposal to assist in spreading neurosurgical best practice on an international scale in a novel and comprehensive way. By incorporating multiple social media platforms into its repertoire, the Atlas is able to ensure awareness of and access to these resources regardless of the user's location or platform of preference. In so doing, the Atlas represents a novel way of advancing access to neurosurgical educational resources in the digital age.

Eponyms in Vascular Neurosurgery: Comprehensive Review of 11 Arteries

OBJECTIVE

Anatomic knowledge and insight depend on the cumulative contributions of anatomists over time, and eponyms pay homage to some of these individuals.

METHODS

A PubMed literature review identified 11 eponymous arteries of the brain and spinal cord.

RESULTS

The 11 eponyms include the artery of Adamkiewicz, the artery of Bernasconi and Cassinari, the artery of Davidoff and Schechter, the recurrent artery of Heubner, McConnell's capsular arteries, the artery of Percheron, the artery of Salmon, the Vidian artery, the arteria termatica of Wilder, the circle of Willis, and the artery of Wollschlaeger and Wollschlaeger.

CONCLUSIONS

Eponyms remind us of an artery's importance and can improve our clinical acumen or technique. They have become an integral part of our day-to-day vocabulary, often without our historical knowledge of these anatomists. This report reviews these histories and the anatomy to deepen our appreciation of arterial eponyms in vascular neurosurgery.

Postoperative 30-day emergency department utilization after 7294 cranial neurosurgery procedures at a tertiary neuroscience center

OBJECTIVE

Hospital readmission and the reduction thereof has become a major quality improvement initiative in organized medicine and neurosurgery. However, little research has been performed on why neurosurgical patients utilize hospital emergency rooms (ERs) with or without subsequent admission in the postoperative setting.

METHODS

This study was a retrospective, single-center review of data for all surgical cranial procedures performed from July 2013 to July 2016 in patients who survived to discharge. The study was approved by the institutional review board of the participating medical center.

RESULTS

The authors identified 7294 cranial procedures performed during 6596 hospital encounters in 5385 patients. The rate of postoperative ER utilization within 30 days after surgical hospitalization across all procedure types was 13.1 per 100 surgeries performed. The two most common chief complaints were pain (30.7%) and medical complication (18.2%). After identification of relevant surgical and patient factors with univariable analysis, a multivariable backward elimination logistic regression model was constructed in which Ommaya reservoir placement (OR 2.65, p = 0.0008) and cranial CSF shunt placement (OR 1.40, p = 0.0001) were associated with increased ER utilization. Deep brain stimulation electrode placement (OR 0.488, p = 0.0004), increasing hospital length of stay (OR 0.935, p < 0.0001), and increasing patient age (OR 0.988, p < 0.0001) were associated with lower rates of postoperative ER utilization. One-half (50%) of ER visit patients were readmitted to the hospital. New/worsening neurological deficit chief complaint (OR 1.99, p = 0.0088), fever chief complaint (OR 2.41, p = 0.0205), altered mentation chief complaint (OR 2.71, p = 0.0002), patient chronic kidney disease (OR 3.31, p = 0.0037), brain biopsy procedure type (OR 3.50, p = 0.0398), and wound infection chief complaint (OR 31.4, p = 0.0008) were associated with increased rates of readmission to the hospital from the ER in multivariable analysis.

CONCLUSIONS

The authors report the rates of and reasons for ER utilization in a large cohort of postoperative cranial neurosurgical patients. Factors identified were associated with both increased and decreased use of the ER after cranial surgery, as well as variables associated with readmission to the hospital after postoperative ER visitation. These findings may direct future quality improvement via prospective implementation of care pathways for high-risk procedures.

Giant diffuse cerebellar AVM: managing ultimate intraoperative challenges

Surgery within the posterior cranial fossa uniquely requires excellence in microsurgical technique, given the complexity of the neurovascular structures housed within this region. Arteriovenous malformations (AVMs) within this region represent the greatest surgical challenge because of the difficulty in resecting an AVM completely while preserving the highly eloquent surrounding structures. The AVM in this video exemplifies a surgeon's "most challenging case," a surgery that spanned two stages, including 14 hours of resection, but concluded with complete resection despite the complexity of deep arterial and dural feeders. The video can be found here: https://youtu.be/WNBuwFHSrQ0.

Contralateral Interhemispheric Transfalcine Transprecuneus Approach: Advancing Operative Angles to Deep-Seated Lesions

The reach to expose the peritrigonal/atrial territories poses special challenges. The highly functional overlying cortices and white matter tracts, such as the optic radiations lateral to the ventricle, postcentral gyrus laterally and more superficially, and the thalamus anteroinferiorly, constrain the surgical corridors to the atrium. Standard interhemispheric or transcortical approaches involve significant retraction and resection of the normal parenchyma. In this offering, the authors describe the contralateral posterior interhemispheric transfalcine transprecuneus approach (PITTA), which provides flexible working angles while protecting the functional brain tissues. In summary, the PITTA is founded on the concept of using a contralateral operative trajectory to augment a more tangential working angle to the more difficult-to-reach lateral target through a midline route. The PITTA emphasizes the importance of operative working angles (versus necessary operative space) through less disruptive exposures as a more viable parameter for achieving desirable results.

Recurrent brainstem cavernous malformations following primary resection: blind spots, fine lines, and the right-angle method

OBJECTIVE

Proximity of brainstem cavernous malformations (BSCMs) to tracts and cranial nerve nuclei make it costly to transgress normal tissue in accessing the lesion or disrupting normal tissue adjacent to the lesion in the separation plane. This interplay between tissue sensitivity and extreme eloquence makes it difficult to avoid leaving a remnant on occasion. Recurrences require operative intervention, which may increase morbidity, lengthen recovery, and add to overall costs. An approximately 20-year experience with patients with recurrent BSCM lesions following primary microsurgical resection was reviewed.

METHODS

A prospectively maintained database of 802 patients who underwent microsurgical resection of cerebral cavernous malformations during 1997-2018 was queried to identify 213 patients with BSCMs. A retrospective chart review was conducted for patients with recurrent BSCM after primary resection who required a second surgery.

RESULTS

Fourteen of 213 patients (6.6%) underwent repeat resection for recurrent BSCM. Thirty-four hemorrhagic events were observed among these 14 patients over 576 patient-years (recurrent hemorrhage rate, 5.9% per year; median discrete hemorrhagic events, 2; median time to rehemorrhage, 897 days). BSCM occurred in the pons in 10 cases, midbrain in 2 cases, and medulla in 2 cases. A blind spot in the operative corridor was the most common cause of residual BSCM (9 patients). All recurrent BSCMs were removed completely, although 2 patients each required 2 operations to treat recurrence. Twelve patients had unchanged or improved modified Rankin Scale scores at last clinical evaluation compared with admission, and 2 patients had worse scores. Recurrence was more common among patients who were operated on in the first versus the second half of the series (8.5% vs 4.7%).

CONCLUSIONS

The 6.6% rate of BSCM recurrence requiring reoperation reflects the fine lines between complete resection and recurrence and between safe and harmful surgery. The detection of remnants is difficult postoperatively and remains so even at 6 months when the resection bed has healed. The 5.9% annual hemorrhage risk associated with recurrent BSCM in this experience is consistent with that reported for unoperated BSCMs. The right-angle method helps to anticipate blind spots and meticulously inspect the resection cavity for residual BSCM during surgery. A low percentage of recurrent BSCM (5%-10%) ensures ongoing effort toward an acceptable balance of safety and completeness.

Prognostic value of the Simpson grading scale in modern meningioma surgery: Barrow Neurological Institute experience

OBJECTIVE

Recently, the prognostic value of the Simpson resection grading scale has been called into question for modern meningioma surgery. In this study, the authors analyzed the relationship between Simpson resection grade and meningioma recurrence in their institutional experience.

METHODS

This study is a retrospective review of all patients who underwent resection of a WHO grade I intracranial meningioma at the authors' institution from 2007 to 2017. Binary logistic regression analysis was used to assess for predictors of Simpson grade IV resection and postoperative neurological morbidity. Cox multivariate analysis was used to assess for predictors of tumor recurrence. Kaplan-Meier analysis and log-rank tests were used to assess and compare recurrence-free survival (RFS) of Simpson resection grades, respectively.

RESULTS

A total of 492 patients with evaluable data were included for analysis, including 394 women (80.1%) and 98 men (19.9%) with a mean (SD) age of 58.7 (12.8) years. The tumors were most commonly located at the skull base (n = 302; 61.4%) or the convexity/parasagittal region (n = 139; 28.3%). The median (IQR) tumor volume was 6.8 (14.3) cm3. Simpson grade I, II, III, or IV resection was achieved in 105 (21.3%), 155 (31.5%), 52 (10.6%), and 180 (36.6%) patients, respectively. Sixty-three of 180 patients (35.0%) with Simpson grade IV resection were treated with adjuvant radiosurgery. In the multivariate analysis, increasing largest tumor dimension (p < 0.01) and sinus invasion (p < 0.01) predicted Simpson grade IV resection, whereas skull base location predicted neurological morbidity (p = 0.02). Tumor recurrence occurred in 63 patients (12.8%) at a median (IQR) of 36 (40.3) months from surgery. Simpson grade I resection resulted in superior RFS compared with Simpson grade II resection (p = 0.02), Simpson grade III resection (p = 0.01), and Simpson grade IV resection with adjuvant radiosurgery (p = 0.01) or without adjuvant radiosurgery (p < 0.01). In the multivariate analysis, Simpson grade I resection was independently associated with no tumor recurrence (p = 0.04). Simpson grade II and III resections resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01) but similar RFS compared with Simpson grade IV resection with adjuvant radiosurgery (p = 0.82). Simpson grade IV resection with adjuvant radiosurgery resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01).

CONCLUSIONS

The Simpson resection grading scale continues to hold substantial prognostic value in the modern neurosurgical era. When feasible, Simpson grade I resection should remain the goal of intracranial meningioma surgery. Simpson grade IV resection with adjuvant radiosurgery resulted in similar RFS compared with Simpson grade II and III resections.

Transtentorial Approach to Parahippocampal Lesions: A Technically Challenging Approach for Preserving Temporal Lobe Structures

In this installment of the Neurosurgical Atlas Series for WORLD NEUROSURGERY, the authors examine the paramedian supracerebellar transtentorial (SCTT) approach as a means of accessing the basal posteromedial temporal lobe for both intradural and extradural lesions. While other approaches, such as the subtemporal, transtemporal, and transsylvian routes, are often used to reach this otherwise impervious region, all of them do so at the expense of supratentorial structural integrity. Despite the long and narrow working distance provided by the SCTT approach, the access it provides to critical, deep-seated regions with little to no associated morbidity makes it our preferred approach in these patients. In this work, we highlight the perioperative considerations for this procedure, discuss the technical nuances of all aspects of the operation, and provide discussion on the approach in the context of its evolution and alternatives.

Treatment of a Fusiform Anterior Cerebral Artery Aneurysm With an A3-A3 Bypass: 2-Dimensional Operative Video

Distal anterior cerebral artery (ACA) aneurysms remain a relatively rare and challenging entity for both open microsurgical and endovascular treatments. These lesions provide a significant surgical challenge because of the narrow interhemispheric surgical field, limited proximal control, common fixation of the aneurysm to the adjacent cingulate gyrus, and possible involvement of an unpaired azygos A2. These challenges result in a known association between distal ACA aneurysms and higher operative morbidity. This video demonstrates indirect obliteration of a prior ruptured fusiform right A2 aneurysm utilizing an A3-to-A3 side-to-side anastomotic bypass with aneurysm trapping. An anterior interhemispheric approach was used for exposure of bilateral ACAs, arteriotomies, microanastomosis, and trapping of the aneurysmal right A2 segment. Postoperatively, the patient's neurological status returned to baseline, and imaging demonstrated evidence of bypass patency with no residual filling of the fusiform aneurysmal segment. This video verifies the feasibility and efficacy of the A3-to-A3 anastomotic bypass for treatment of distal ACA aneurysms. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Hunterian Ligation With Distal Revascularization for Management of a Previously Coiled Giant Internal Cerebral Artery Aneurysm: 2-Dimensional Operative Video

Unclippable giant aneurysms pose a significant microsurgical challenge. Options for management are highly dependent on the aneurysm characteristics and cerebrovascular anatomy. Hunterian (proximal) ligation with either high-flow or low-flow distal revascularization is an option for the treatment of aneurysms of the internal carotid artery (ICA). This patient had a multiply recurrent supraclinoid ICA aneurysm following endovascular treatment and progressive ipsilateral homonymous hemianopsia. In preparation for the clip occlusion of the proximal ICA, the patient underwent a balloon test occlusion of the ICA, which had a negative result, indicative of tolerance. A pterional craniotomy was used to perform a low-flow bypass, superficial temporal artery to M2, and clip occlusion of the proximal ICA. The patient tolerated the procedure well with some pressure-dependent contralateral symptoms, which resolved. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Left Modified Orbitozygomatic Approach for Clipping of Multilobulated Middle Cerebral Artery Bifurcation Aneurysm: 2-Dimensional Operative Video

Middle cerebral artery (MCA) aneurysms are associated with one of the most favorable approaches for microsurgical treatment; however, aneurysm geometrics can pose challenges during clip application. The surgeon must be mindful of the clip configuration options available during the planning of ideal clip occlusion for irregular or multilobulated aneurysm domes. This patient had an incidental multilobulated MCA bifurcation aneurysm and underwent an orbitozygomatic approach for microsurgical treatment. Proximal and distal control of the aneurysm were achieved, and complete clip occlusion was achieved following the placement of a single permanent clip. Flow within the parent vessel was well preserved, and complete aneurysm occlusion was achieved. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Optic Nerve Decompression from Coil Mass Impingement and Adhesion Following Large Internal Cerebral Artery Aneurysm Coil Embolization: 2-Dimensional Operative Video

Aneurysmal mass effect is a consideration for treatment modality selection, particularly in the setting of cranial neuropathy or obstructive hydrocephalus. However, the extent of consequences related to mass effect is not always apparent periprocedurally from the original treatment. This unique video highlights a patient who underwent previous coil occlusion of a supraclinoid internal carotid artery (ICA) aneurysm with subsequent occlusion of the ipsilateral ICA who presented 16 yr later with progressive worsening hemianopsia. The preoperative imaging was suggestive of coil mass impingement prompting operative intervention for decompression. Intraoperative inspection demonstrated that the coil mass was exerting mass effect on the optic nerve and had partially migrated out of the aneurysm dome into the optic nerve. The ICA was also transected and mobilized to further reduce mass effect. Careful microsurgical decompression was achieved and prevented further visual compromise. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Microsurgical Clipping of an Unruptured Basilar Apex Aneurysm: 2-Dimensional Operative Video

Aneurysms of the basilar artery apex are generally at an increased risk of rupture compared with aneurysms in other locations, and the risk of rupture increases with increasing aneurysm size. Therefore, these lesions necessitate treatment to decrease the risk of rupture. The location, size, and directionality of dome projection influence the difficulty of microsurgical treatment. The patient presented with an incidental basilar apex aneurysm identified on workup for headaches. The aneurysm projected superoposteriorly into the interpeduncular cistern. The surgical approach involved a wide exposure of the basilar apex complex and meticulous identification and preservation of P1 perforators during clip applications. It was imperative to visualize all perforators on both sides of the clip prior to application, given the severe morbidity associated with a perforator infarct. The patient tolerated the procedure well and remained neurologically intact after the operation. This video is an exemplary demonstration of basilar apex aneurysm clip application for an incidentally discovered aneurysm. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Clipping of Complex Internal Cerebral Artery Terminus Aneurysm: 2-Dimensional Operative Video

Internal carotid artery (ICA) bifurcation, or terminus, aneurysms are uncommon, and although they can be accessed with relative ease, clip occlusion of such aneurysms is often challenging due to the close proximity of basal forebrain perforator vessels. This patient had an incidentally discovered ICA terminus aneurysm and elected for microsurgical clipping. A modified orbitozygomatic approach was used to approach the aneurysm. The clipping was significantly complicated by the adherence and close proximity of the recurrent artery of Heubner to the aneurysm dome. Following successful dissection of the artery from the aneurysm dome and complete visualization of the aneurysm neck to avoid violation of perforator flow, successful clip occlusion of the aneurysm was achieved. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Intraoperative Rerupture and Surgical Clipping of a Small Superiorly Projecting Anterior Communicating Artery Aneurysm: 2-Dimensional Operative Video

Anterior communicating artery (ACoA) aneurysms are prone to rupture even at smaller sizes. The surgical management of ACoA aneurysms is highly dependent on the spatial orientation of the saccular projection, categorized as inferior, superior, anterior, or posterior. Superior projecting aneurysms constitute approximately one-third of all aneurysms involving the ACoA. These aneurysms commonly project within the interhemispheric fissure; however, if the aneurysm is not high-riding, it can often be approached via a transsylvian trajectory. The patient presented after subarachnoid hemorrhage with a 3-mm superiorly projecting ACoA aneurysm. The lesion was approached via a right modified orbitozygomatic craniotomy with a transsylvian trajectory. The aneurysm reruptured after minimal manipulation of the dome. Mitigation of the intraoperative rupture was achieved through temporary clip application to bilateral A1 vessels. Bipolar coagulation and placement of 2 permanent clips facilitated final aneurysm occlusion. Postoperative imaging demonstrated patent bilateral A2 flow and no residual aneurysm filling. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Surgical Challenges Associated With Anterior Choroidal Artery Aneurysm Clipping: 2-Dimensional Operative Video

Surgical treatment of anterior choroidal artery (AChA) aneurysms is challenging because of the constrained operative corridor and limitations imparted by the surrounding rigid structures during the exposure. The AChA most commonly arises as a single branch from the communicating (C7) segment of the internal carotid artery but has 2 to 4 branches in approximately one-third of cases, and aneurysms generally arise from the parent vessel interface with these branches. This patient experienced a sentinel headache 4 d before presenting with subarachnoid hemorrhage. The patient had a large right AChA aneurysm with a unique configuration in which the parent vessel was located anterior to the aneurysm. Endovascular therapy was aborted because there was an AChA branch at the base of the aneurysm. An orbitozygomatic craniotomy was performed that provided transsylvian access to the region of interest. Clip application was challenging because of the close proximity of the branch vessels. Intraoperative indocyanine green evaluation and postoperative angiogram showed patency of the AChA and posterior communicating artery. This video demonstrates the surgical challenge associated with AChA aneurysms because of the proximity of adjacent structures and highlights the importance of meticulous technique during clip application. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Clipping of Basilar and Middle Cerebral Artery Aneurysms: 2-dimensional operative video

Careful preoperative planning for patients with multiple intracranial aneurysms is paramount given the importance of an appropriate trajectory and exposure for each aneurysm that will be clipped. The general principle is to clip aneurysms in a retrograde manner, such that more distal aneurysms are clipped earlier, and more superficial aneurysms are clipped later. This patient had unruptured middle cerebral artery (MCA) and basilar artery (BA) apex aneurysms and elected for surgical clipping of both lesions. An orbitozygomatic craniotomy ipsilateral to the MCA aneurysm was performed to permit clipping of both lesions. The dissection initially focused on exposure of the MCA aneurysm and then focused on the carotid-oculomotor triangle to permit basilar apex exposure and aneurysm clipping. The MCA aneurysm was clipped second. Postoperative imaging demonstrated complete obliteration of both aneurysms. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Transpetrous Clip Occlusion of a Giant Midbasilar Aneurysm Using Hypothermic Cardiac Arrest: 2-Dimensional Operative Video

Basilar trunk aneurysms are historically associated with extremely high morbidity. The complexity of circumflex perforator arteries responsible for the perfusion of the brainstem makes surgical intervention for these lesions particularly challenging. This patient had a giant midbasilar aneurysm that encompassed multiple perforators but was associated with progressive mass effect and debilitating morbidity. Therefore, a transpetrous approach was used with transposition of the facial nerve and sacrifice of the vestibulocochlear nerve to permit access to the aneurysm. Hypothermic cardiac arrest was used to permit dome manipulation with a tandem fenestrated clipping of the aneurysm. Postoperative imaging demonstrated a reduction in mass effect attributable to the significantly reduced dome size and persistence of flow via a reconstructed basilar trunk. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.