Novel classification of foramen magnum meningiomas predicted by topographic position relative to neurovascular bundle.

PURPOSE: Proximity to critical neurovascular structures can create significant obstacles during surgical resection of foramen magnum meningiomas (FMMs) to the detriment of treatment outcomes. We propose a new classification that defines the tumor's relationship to neurovascular structures and assess correlation with postoperative outcomes. METHODS: In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor. RESULTS: The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission. CONCLUSION: The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions.

Endoscopic Approaches to the Paramedian Skull Base: An Anatomic Comparison of Contralateral Endonasal and Transmaxillary Strategies.

BACKGROUND: The expanded endoscopic endonasal approach (EEA) is limited laterally by the internal carotid artery (ICA). The EEA to the paramedian skull base often requires complex maneuvers such as dissection of the Eustachian tube (ET) and foramen lacerum (FL), and ICA manipulation. An endoscopic contralateral transmaxillary approach (CTMA) has the potential to provide adequate exposure of the paramedian skull base while bypassing manipulation of the aforementioned anatomic structures. OBJECTIVE: To quantify and compare the surgical nuances of a CTMA and a contralateral EEA when approaching the paramedian skull base in cadaveric specimens. METHODS: Five adult cadaveric heads were dissected bilaterally (10 sides) using a contralateral EEA and a CTMA to expose targets of interest at the paramedian skull base. For each target in both approaches, the surgical freedom, angle of attack, the corridor's "perspective angle," and "turning angle" to circumvent the ICA, ET, and FL were obtained. RESULTS: The CTMA achieved superior surgical freedom at all targets ( P < .05) except at the root entry point of cranial nerve XII. The CTMA provided superior vertical and horizontal angles of " attack " to the majority of targets of interest. Except when approaching the root entry point of cranial nerve XII, the CTMA " turning angle " around the ICA, ET, and FL were wider with CTMA for all targets. CONCLUSION: A CTMA complements the EEA to access the paramedian skull base. A CTMA may limit the need for complex maneuvers such as ICA mobilization and dissection of the ET and FL when approaching the paramedian skull base.

Quantitative Comparative Analysis of the Endoscope-Assisted Expanded Retrosigmoid Approach and the Far-Lateral Approach to the Inframeatal Area: An Anatomic Study With Surgical Implications.

BACKGROUND: The inframeatal area (IFMA) is a complex anatomic region of the posterior cranial fossa. Given its deep-seated location, tumors involving the IFMA represent a surgical challenge. OBJECTIVE: To objectively compare the endoscope-assisted expanded retrosigmoid approach (ERSA) and the far-lateral supracondylar transtubercular approach (FLTA) to address the IFMA. METHODS: Anatomic dissections were performed on 5 cadaveric heads (10 sides). The ERSAs were performed before and after the FLTAs. The surgical exposure, surgical freedom, and angles of attack to the IFMA were measured and compared for each approach. In addition, 2 illustrative clinical cases are reported. RESULTS: Compared with FLTA, ERSA yielded a nonsignificantly smaller mean area of exposure, whereas FLTA provided a significantly larger mean area of surgical freedom, compared with ERSA ( P = .002). The mean horizontal and vertical angles of attack were significantly different between the approaches. In the vertical plane, FLTA yielded the broadest angle of attack at the root entry zone of the lower cranial nerves (CN; P < .004), whereas ERSA did so at the dural entry zone of CN VII/VIII ( P = .006). In the horizontal plane, FLTA achieved its broadest angle of attack at the root entry zone of the lower CNs ( P = 1.83) while ERSA at the dural entry zone of CN VII/VIII ( P = .37). CONCLUSION: ERSA and FLTA granted a comparable exposure with the IFMA. Although FLTA may afford a larger area of surgical freedom, ERSA may be a suitable alternative to approach the IFMA, particularly to reach the most medial and superior aspects of this region. Conversely, FLTA may facilitate access to more caudally targets.

The "Crista Ovale": A Reliable Anatomical Landmark in Transorbital Endoscopic Approaches to the Middle Cranial Fossa.

BACKGROUND: Transorbital endoscopic approaches (TOEAs) have emerged as adjunct and alternatives for accessing the middle cranial fossa (MCF). Nuances of the skull base anatomy from a ventral transorbital endoscopic viewpoint remain to be fully described. OBJECTIVE: To assess the anatomy of the "crista ovale" (COv), described transcranially as the midsubtemporal ridge (MSR), from a ventral transorbital perspective and evaluate its role as a landmark in TOEA to the MCF. METHODS: Lateral TOEAs to the MCF were performed in 20 adult cadaveric heads (40 sides). The presence of the COv/MSR was evaluated under endoscopic visualization. Anatomic relationships between COv/MSR and surrounding structures were assessed. The presence of COv/MSR was also examined in 30 cadaveric head computed tomography (CT) scans (60 sides). RESULTS: The COv/MSR was identified in 98% (39/40) of sides at the MCF, as 1 of 4 major configurations. The COv/MSR was found anterolateral to the foramen ovale and foramen spinosum (mean distance: 9.2 ± SD 2.4 mm and 12.3 ± SD 2.6 mm, respectively) directly anterior or anteromedial to the petrous apex (mean distance: 26.2 ± SD 2.6 mm) and at a mean 47.6 ± SD 4.7 mm from the approach's surgical portal. It was recognized in 95% (57/60) of CT scans. CONCLUSION: The COv/MSR can be readily identified during TOEA to the MCF and on CT. It serves as a reliable landmark to localize the foramen ovale, foramen spinosum, and petrous apex. Further studies may confirm its surgical significance in transorbital endoscopic procedures.

An update of predictors of cerebral infarction after aneurysmal subarachnoid hemorrhage: systematic review and meta-analysis.

INTRODUCTION: Evidence about predictors of poor outcomes such as cerebral infarction (CI) after aneurysmal subarachnoid hemorrhage (aSAH) has not been fully elucidated. EVIDENCE ACQUISITION: We performed a systematic review and meta-analysis on studies with adults with aSAH considering RCT and non-RCT, prospective, and retrospective cohort studies describing clinical, imaging as well as angiographic studies in patients with aSAH. EVIDENCE SYNTHESIS: After reviewing the complete text, 11 studies were considered eligible, out of which four were ruled out. Degree of clinical severity was the most predictive factor with a higher degree at the presentation on different severity scales being associated with a statistically significant increasing the risk of suffering a CI following aSAH (OR 2.49 [95% CI 1.38-4.49] P=0.0003). Aneurysm size increased the risk of CI (OR 1.49 [95% CI 1.20-1.85] P=0.0003; I2=4%). In six studies analyzed, it was found that an important factor for the subsequent development of CI is vasospasm (OR 7.62 [2.19, 26.54], P=0.0001). CONCLUSIONS: The development of vasospasm is a risk factor for CI development after aSAH. In our review, three factors were associated with an increased risk of CI: clinical severity at presentation, vasospasm, and aneurysm size. The major limitation of this meta-analysis is that included studies were conducted retrospectively or were post hoc analyses of a prospective trial.

A two-stage combined anterolateral and endoscopic endonasal approach to the petroclival region: an anatomical study and clinical application.

OBJECT: The pretemporal transcavernous anterior petrosal (PTAP) approach and the combined petrosal (CP) approach have been used to resect petroclival meningiomas (PCMs). In this cadaveric anatomical study, a two-stage combined PTAP and endoscopic endonasal far medial (EEFM) approach (the PTAPE approach) was compared morphometrically to the CP approach. A case study provides a clinical example of using the PTAPE approach to treat a patient with a PCM. The key elements of the approach selection process are outlined. METHODS: Five cadaveric specimens underwent a CP approach and 5 underwent a PTAPE approach. The area of drilled clivus, length of multiple cranial nerves (CNs), and the area of brain stem exposure were measured, reported as means (standard deviations) by group, and compared. RESULTS: The total area of the clivus drilled in the PTAPE group (695.3 [121.7] mm2) was greater than in the CP group (88.7 [17.06] mm2, P < 0.01). Longer segments of CN VI were exposed via the PTAPE than the CP approach (35.6 [9.07] vs. 16.3 [6.02] mm, P < 0.01). CN XII (8.8 [1.06] mm) was exposed only in the PTAPE group. Above the pontomedullary sulcus, the total area of brain stem exposed was greater with the PTAPE than the CP approach (1003.4 [219.5] mm2 vs. 437.6 [83.7] mm2, P < 0.01). Similarly, the total exposure of the medulla was greater after the PTAPE than the CP exposure (240.2 [57.06] mm2 vs. 48.1 [19.9] mm2, P < 0.01). CONCLUSION: A combined open-endoscopic paradigm is proposed for managing large PCMs. This approach incorporates the EEFM approach to address the limitations of the PTAP and the CP approach in a systematic fashion. Understanding the anatomical findings of this study will aid in tailoring surgical approaches to patients with these complex lesions.

Endocrinological outcomes after transcranial resection of tuberculum sellae meningiomas: a systematic review and meta-analysis.

Tuberculum sellae meningiomas (TSMs) arise from the anterior skull base. Endocrine status after TSM resection is an important determinant of quality of life. We sought to better characterize the risk of postoperative endocrinopathy for patients with TSM undergoing open transcranial approach (TCA) microsurgical resection. A systematic review was conducted following MOOSE and PRISMA guidelines. Results were screened against predefined criteria, which included studies evaluating endocrinopathy rates after open transcranial microsurgery for TSM. Outcome incidence was calculated using random-effect meta-analysis of proportions. Eight studies met the inclusion criteria, comprising 406 patients. The average age of the cohort was 52.2 years, and a majority (70%) of the patients were female. The pooled incidence of postoperative transient diabetes insipidus (DI) was 7.5% (95% CI 2.9-12%; p = 0.001; I2 = 75.9%) and permanent DI was 1.6% (95% CI 0.3-2.7%; p = 0.01; I2 = 0%). The pooled rate of postoperative hypopituitarism was 3.6% (95% CI 1.6-5.7%; p < 0.001; I2 = 22.2%), while the incidence of hyperprolactinemia was 1.3% (95% CI 0.1 = 2.6%; p = 0.036; I2 = 8.74%). The incidence of SIADH was 4% in one study but was not included in the meta-analysis. Endocrinopathy after TSM microsurgical resection is rare, but the available studies' poor quality of evidence and inconsistent methodology may reflect that it is underreported in the literature. Nevertheless, clinicians should consider the risk of hormonal impairment and counsel their patients accordingly when selecting a TCA for these lesions.

Morphometric comparison of Fisch type A and endoscopic endonasal far-medial supracondylar approaches to the jugular foramen.

OBJECTIVE: The jugular foramen (JF) is one of the most complex and challenging skull base regions to approach surgically. The extreme medial approach to access the JF provides the approach angle from an anterior direction and does not require dissection and sacrifice of the jugular bulb (JB) to reach the pars nervosa. The authors compared the Fisch type A approach to the extreme medial approach to access the JF and evaluated the usefulness of the extreme medial approach. METHODS: This study was performed at the Anatomical Laboratory for Visuospatial Innovations in Otolaryngology and Neurosurgery of The Ohio State University. For the comparison of surgical maneuverability and visualization, two angles were measured: 1) the angle of attack (AoA), defined as the widest angle of movement achieved with a straight dissector; and 2) the angle of endoscopic exposure (AoEE), defined as the widest angle of movement in the nasal cavity. The differences in eustachian tube (ET) management, approach angle, surgical maneuverability, and surgical application of the Fisch type A approach to the extreme medial approach were compared. RESULTS: There was no difference between ET mobilization and transection regarding cranial-caudal (CC) or medial-lateral (ML) AoA (p = 0.646). The CC-AoA of the Fisch type A approach was significantly wider than the CC-AoA of the extreme medial approach (p = 0.001), and the CC-AoEE was significantly wider than the CC-AoA of the extreme medial approach (p < 0.001). There was no significant difference between the CC-AoA of the Fisch type A approach and the CC-AoEE. The ML-AoA of the Fisch type A approach was significantly wider than the ML-AoA of the extreme medial approach (p = 0.033), and the ML-AoEE was significantly wider than ML-AoA in the extreme medial approach (p < 0.001). The ML-AoEE was significantly wider than the ML-AoA in the Fisch type A approach (p = 0.033). CONCLUSIONS: The surgical maneuverability of the extreme medial approach was not inferior to that of the Fisch type A approach. The extreme medial approach can provide excellent surgical field visualization, while preserving the JB. Select cases of chordomas, chondrosarcomas, and JF schwannomas should be considered for an extreme medial approach. These two approaches are complementary, and a case-by-case detailed analysis should be conducted to decide the best approach.

Nervus Intermedius Outcomes After Vestibular Schwannoma Surgery and Radiosurgery: A Single-Institution Experience.

OBJECTIVE: Nervus intermedius (NI) dysfunction after the management of vestibular schwannoma (VS) is underreported and is experienced by patients undergoing stereotactic radiosurgery and surgical resection. The aim of this study was to present NI outcomes in a series of patients who underwent all treatment modalities for VS and to review the existing literature. METHODS: We performed a retrospective review of all patients with VS who were treated at our institution between January 1, 2008, and December 31, 2018. Demographic data, tumor size, Koos grade, treatment modality, extent of resection, postoperative facial nerve function, and hearing function were collected. NI outcomes were determined from phone interview using a previously published functional questionnaire. RESULTS: Of 222 patients who were reviewed, 98 patients responded to the questionnaire. Patients were stratified into 3 groups: group 1, 54 patients who underwent radiation; group 2, 27 patients who underwent surgical treatment; group 3, 17 patients who underwent both radiation and surgery. Of patients, 28% presented with preoperative NI dysfunction, most commonly dry eye followed by taste dysfunction and lacrimation dysfunction. Following treatment, 79% of patients experienced NI dysfunction, most commonly dry eye. Statistical differences in dry eye and taste dysfunction were observed when comparing the treatment groups. CONCLUSIONS: NI dysfunction is common following treatment for VS and should be included in pretreatment counseling of patients, as it may impact treatment choice and quality of life. Additional studies are warranted to fully characterize NI dysfunction after treatment.

Evidence-based medicine in neurosurgery: why and how?

Since its inception, medical training and practice are based primarily on the clinical experience provided by the mentors of each of the medical schools. In the 1990s, the first steps were taken for the construction of what we now know as evidence-based medicine. Evidence-based medicine is the set of studies, methods, and principles for the prevention of medical diseases, management guidelines, and algorithms used in sources of evidence. Neurosurgery based on evidence has emerged thanks to advances in neuroscience and information technology that allows the globalization of current scientific information. The results of important reviews on the levels of evidence in neurosurgery are low in percentages of high-quality evidence in this field of medicine. Based on the above, the aim of this manuscript was to describe the application of evidence in neurosurgery, the current state of the art in evidence-based medicine, and the steps needed to create evidence of the best quality in neurosurgery.

Third Ventricle Volume Predicts Functional Outcome in Chronic Subdural Hematoma.

OBJECTIVES: There is a lack of evidence demonstrating the utility of computed tomography (CT) to predict chronic subdural hematoma (CSDH) clinical outcomes. We aim to analyze the role of tomographic volumetric analysis in patients with CSDH. METHODS: We performed a retrospective study of patients undergoing burr-hole craniostomy (BHC) for CSDH over five years at a tertiary care center. Degree of midline shift, radiographic density, subdural hematoma volume, acute blood volume, and third ventricle (3VV) and fourth ventricle (4VV) volume were estimated using semiautomatic segmentation of preoperative CT. Postoperative functional outcome was measured by two endpoints: National Institute of Health Stroke Scale (NIHSS) at discharge and short-term modified Rankin Scale (mRS) at 6-week follow-up. Univariate and multivariate analyses were performed using nonparametric tests. Discriminative capacity and optimal thresholds of independent variables were calculated by means of receiving-operative curves (ROC). RESULTS: A total of 79 patients were included for analysis with a median age of 78.5 years. Greater preoperative 3VV independently correlated with poor discharge NIHSS (p = .01) and short-term mRS (p = .03). A cutoff value of 0.545 mL demonstrated the highest sensitivity (77.1%) and specificity (88.8%) with an odds ratio for an mRS functional dependence of 9.29 (p = .001). CONCLUSIONS: Greater preoperative tomographic 3VV independently prognosticates poor discharge NIHSS and 6-week mRS. A threshold 3VV of 0.545 mL can be used to identify patients at higher risk of being dependent at first protocolized follow-up.

Hydroxyapatite cement cranioplasty for reconstruction of translabyrinthine approach: aesthetic results, long-term satisfaction, quality of life, and complications.

BACKGROUND: Translabyrinthine approaches (TLAs) for resection of skull base neoplasms are complex with variable reconstruction techniques. Fat grafts in conjunction with hydroxyapatite bone cement techniques have seldom been described in terms of possible superiority to other skull base reconstruction techniques. We sought to determine the impact of this skull base reconstruction technique on clinical outcomes and patient's satisfaction. METHOD: We performed a retrospective analysis of all patients who underwent translabyrinthine approaches for resection of CPA lesions over a 5-year period. Both post-op objective and subjective markers of reconstruction, as well as postoperative complications, were collected and analyzed. RESULTS: Sixty-nine patients were included, 34 underwent reconstruction with hydroxyapatite and fat (rHAC) and 35 with fat alone (rF). rHAC was associated with fewer cranial wound superficial infection/dehiscence (0% vs 14.3%; p = 0.029) and shorter length of stay (mean ± standard deviation) (6.9 ± 7.4 vs 4.4 ± 3.7 days, p = 0.008). Postoperative subjective characterization of rHAC demonstrated improved satisfaction scores (1.38 ± 0.5 vs 1.83 ± 1; p = 0.049) and fewer reports of post-operative irregularities (11.5% vs 37.5%; p = 0.017). CONCLUSION: The use of hydroxyapatite for cranial reconstruction after translabyrinthine approaches has improved patient satisfaction and decreased cranial defects in our small series. Postoperative complications are consistent with other described methods, but with shorter hospital stay, decreased risk of superficial wound dehiscence/infection, and a perceived superiority in preventing percutaneous post-op CSF leaks.

Soft Gasket Seal Reconstruction After Endoscopic Endonasal Transtuberculum Resection of Craniopharyngiomas.

BACKGROUND: The expanded endoscopic endonasal approach (EEA) is currently well accepted for a variety of ventral skull base tumors. Such an approach often results in a transdural defect and intraoperative cerebrospinal fluid (CSF) leak, and adequate reconstruction is necessary to prevent postoperative CSF leak and its complications. Reconstruction is usually performed using a variety of materials along with the nasoseptal flap. OBJECTIVE: This work's aim is to describe a new reconstructive technique called the "soft gasket seal" (SGS) in detail and compare it with the standard reconstructive technique at our institution for craniopharyngiomas operated via transtuberculum EEA. METHODS: A retrospective chart review was achieved to identify patients who underwent transtubercular EEA for craniopharyngioma between 2010 and 2018, by the same neurosurgical and otolaryngology team using either the SGS or standard reconstructive technique. RESULTS: Of 36 patients who met criteria and were considered for analysis, 15 of them underwent SGS reconstruction and 21 had standard reconstruction. There were 16 female (44%) and 20 male (56%) patients. The median age was 42.2 ± 20.9 years. The rate of postoperative CSF leak in the group of patients treated with the standard technique was 14.2% and 6.6% in the SGS group (odds ratio 0.43 [confidence interval 95% 0.007-6.15], P = 0.62). CONCLUSIONS: The SGS technique provides a simple reconstructive technique in conjunction with the nasoseptal flap, showing a tendency of lower complications when compared with our standard technique while avoiding donor site morbidity. Such results are encouraging, but further studies are necessary to confirm these findings.

Impact of the Extent of Microsurgical Resection in Sphenopetro-clival Meningiomas Trough a Multistaged Approach: A Volumetric Analysis.

Objective Sphenopetroclival meningiomas (SPCMs) represent a challenge for surgical treatment. The authors used an objective volumetric analysis to assess the effect of the grade of resection and different surgical strategies that may affect the outcome of this tumors. Methods Over a period of 4 years, patients with SPCMs were treated using a middle versus posterior fossa approach, or a two-stage surgery combining both approaches, based on the tumor location in relation to the petrous ridge and tumor volume. Retrospectively, all cases were analyzed with regard to tumor volume, extent of resection (EOR), functional outcome, and complications. Results Twenty-seven patients with SPCMs met the inclusion criteria, and the mean follow-up was 24.8 months. Eleven patients underwent a two-stage surgery, while 16 patients had their SPCMs resected via a single craniotomy. Mean EOR was 87.6% and gross total resection was achieved in 48% of patients. Patients with greater EOR had better functional outcomes ( r = 0.81, p < 0.01). Greater EOR was not accompanied by a significant increase in surgical complications. There was a trend toward lower postoperative volumes and better EOR with our two-stage approach (2.2 vs. 3.2 cm 3 , p = 0.09; and 94.1 vs. 91.2%, p = 0.49, respectively), without an increase in the rate of complications (18.7 vs. 18.2%, p = 0.5). Conclusion Staging of the surgical resection of larger tumors may lead to greater EOR, and this strategy should be considered for larger tumors.

Combined biportal unilateral endoscopic endonasal and endoscopic anterior transmaxillary approach for resection of lesions involving the infratemporal fossa.

BACKGROUND: Approaching tumors involving the infratemporal fossa (ITF) is technically challenging due to the complex relationships between several neurovascular structures and the deep-seated location of these lesions. METHODS: The authors describe in detail a minimally invasive approach to the ITF, consisting on a single-nostril endoscopic endonasal transmaxillary approach aided by an anterior transmaxillary port (EEA-ATMa). Anatomical landmarks and surgical tenets of this approach are highlighted and reviewed with the goal to guarantee successful tumor resection and avoid operative complications. CONCLUSION: The EEA-ATMa is technically feasible and offers excellent surgical exposure to the anterior and lateral aspect of ITF, without the need of transecting the Vidian nerve or performing a wide septectomy.

The Minimally Invasive Posterolateral Transcavernous-Transtentorial Approach. Technical Nuances, Proof of Feasibility, and Surgical Outcomes Throughout a Case Series of Sphenopetroclival Meningiomas.

OBJECTIVE: Sphenopetroclival (SPC) meningiomas are considered among the most complex skull-base neoplasms to approach surgically. We aim to determine whether some SPC meningiomas can be safely and effectively treated using a modified minimally invasive pterional posterolateral transcavernous-transtentorial approach (MIPLATTA). METHODS: Fourteen patients harboring SPC meningiomas were surgically treated through a MIPLATTA. MIPLATTA includes a minipterional craniotomy, anterior extradural clinoidectomy, peeling of the temporal fossa, decompression of cranial nerves (CNs) in the cavernous sinus, and sectioning of the tentorium to reach the upper part of the posterior fossa. RESULTS: Gross total resection was achieved in 11 of 14 patients (78%), whereas near-total resection was accomplished in the other 3 patients (22%), each of whom underwent a further complementary retrosigmoid approach for gross total tumor resection. There were no deaths, and 13 of 14 patients were independent at 6 months follow-up (modified Rankin Scale score ≤2). One patient had pontine infarction after the procedure and experienced moderate disability at follow-up (modified Rankin Scale score 3). All patients had some degree of CN impairment. Of 38 cranial neuropathies, 15 (39%) improved, 20 (53%) remained stable, and 3 (8%) worsened postoperatively. Four new CN deficits were observed postoperatively in 3 patients (fourth CN, 2 patients; third CN, 1; fifth CN, 1). CONCLUSIONS: MIPLATTA is a useful and safe treatment alternative that allows resection of large SPC tumors with dominant invasion of cavernous sinus and middle fossa, preserves hearing and facial motor function, and provides good chances of recovery of visual and oculomotor deficits.