Resection of the quadrangular lobule of the cerebellum to increase exposure of the cerebellomesencephalic fissure: an anatomical study with clinical correlation.

OBJECTIVE: The lateral aspect of the cerebellomesencephalic fissure frequently harbors vascular pathology and is a common surgical corridor used to access the pons tegmentum, as well as the cerebellum and its superior and middle peduncles. The quadrangular lobule of the cerebellum (QLC) represents an obstacle to reach these structures. The authors sought to analyze and compare exposure of the cerebellar interpeduncular region (CIPR) before and after QLC resection and provide a case series to evaluate its clinical applicability. METHODS: Forty-two sides of human brainstems were prepared with Klingler's method and dissected. The exposure area before and after resection of the QLC was measured and statistically studied. A case series of 59 patients who underwent QLC resection for the treatment of CIPR lesions was presented and clinical outcomes were evaluated at 1-year follow-up. RESULTS: The anteroposterior surgical corridor of the CIPR increased by 10.3 mm after resection of the QLC. The mean exposure areas were 42 mm2 before resection of the QLC and 159.6 mm2 after resection. In this series, ataxia, extrapyramidal syndrome, and akinetic mutism were found after surgery. However, all these cases resolved within 1 year of follow-up. Modified Rankin Scale score improved by 1 grade, on average. CONCLUSIONS: QLC resection significantly increased the exposure area, mainly in the anteroposterior axis. This surgical strategy appears to be safe and may help the neurosurgeon when operating on the lateral aspect of the cerebellomesencephalic fissure.

Bibliometric Analysis: Six Decades of Scientific Production from a Nationwide Institution: Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado (ISSSTE) from Mexico.

BACKGROUND: This study employed bibliometric analysis to ascertain the research focus areas among a group of Mexican physicians affiliated with the Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado (ISSSTE). ISSSTE, a healthcare institution catering to a diverse range of diseases, offers a distinctive perspective on the investigated specialties within the realm of health. The primary objective was to identify knowledge gaps in medical care disciplines through a comprehensive examination of scholarly publications. METHODS: We retrieved Scopus papers affiliated with "ISSSTE" and saved them as .CSV files. Subsequently, we employed VOSviewer, biblioshiny, and bibliometrix for bibliometric analysis. This enabled us to identify prominent institutions, prolific authors, highly cited researchers, and their respective affiliations. RESULTS: Our analysis identified 2063 publications; the specialty internal medicine accounted for the greatest proportion with 831 publications. Original papers accounted for 82% of the total, with 52% of them being written in Spanish. The majority of scientific output, 92%, originated from Mexico City. The annual production has steadily increased since 2010, peaking in 2021 with over 200 publications. However, papers on prevalent conditions, such as metabolic syndrome, received limited citations, and the L0 index (percentage of uncited items) for all papers is close to 60%. Scopus mislabeled one affiliation, and some cases show a low paper-to-author ratio of 0.5 Discussion: Additional concerns, such as honorary authorship due to excessive authors per paper, and the underlying causes of low citation rates in Mexican publications, warrant further examination. Moreover, our research emphasizes the urgency of bolstering research and development funding, which was consistently below 0.5% of GDP for the past four decades, falling short of legal mandates and international benchmarks. We endorse the establishment of robust research collectives in Latin America to address these challenges, foster regional scientific output, and transition from knowledge consumers to knowledge producers, thereby reducing dependence on foreign technology.

Extended resection for seizure control of pure motor strip focal cortical dysplasia during awake craniotomy: illustrative case.

BACKGROUND: Focal cortical dysplasias (FCD) represent highly intrinsically epileptogenic lesions that require complete resection for seizure control. Resection of pure motor strip FCD can be challenging. Effective control of postoperative seizures is crucial and extending the boundaries of resection in an eloquent zone remains controversial. OBSERVATIONS: The authors report a 52-year-old right-handed male with refractory epilepsy. The seizure phenotype was a focal crisis with preserved awareness and a clonic motor onset of right-hemibody. Epilepsy surgery protocol demonstrated a left pure motor strip FCD and a full-awake resective procedure with motor brain mapping was performed. Further resection of surgical boundaries monitoring function along intraoperative motor tasks with no direct electrical stimulation corroborated by intraoperative-neuromonitorization was completed as the final part of the surgery. In the follow-up period of 3-years, the patient has an Engel-IB seizure-control with mild distal lower limb palsy and no gate compromise. LESSONS: This report represents one of the few cases with pure motor strip FCD resection. In a scenario similar to this case, the authors consider that this variation can be useful to improve seizure control and the quality of life of these patients by extending the resection of a more extensive epileptogenic zone minimizing functional damage.

Operative considerations and surgical treatment of sylvian fissure arteriovenous malformations: a 20-year experience.

OBJECTIVE: Sylvian fissure (SF) arteriovenous malformations (AVMs) are among the most challenging vascular lesions amenable to neurosurgical treatment and account for 10% of all locations. As radiosurgery and endovascular techniques are increasingly involved in multimodal management protocols, the role of microsurgery needs to be reassessed as a stand-alone technique. The aim of this study was to show that total excision can be achieved with reasonable levels of morbidity and mortality in a real-world setting from a specialized high-volume center. METHODS: Forty-three patients with SF AVMs were identified from a series of 577 AVM patients treated microsurgically over a 22-year period. The mean patient age was 33.07 years (range 15-60 years), and there were 22 male and 21 female patients. The mode of presentation was headache in 51.2%, hemorrhage in 34.9%, seizures in 30.2%, and steal phenomenon in 9.3%. The authors analyzed the anatomical basis and angiographic characteristics of such lesions. RESULTS: In the preoperative period, 83.7% of the patients had a modified Rankin Scale (mRS) score of 0-2, and 16.3% had an mRS score of 3-5. After a 12-month follow-up, 95.3% of patients had an mRS score of 0-2, and 4.7% had a score of 3-6. The difference between pre- and postoperative scores was not statistically significant. SF AVMs have several particular features: 1) They produce angiographic steal of the anterior cerebral artery. 2) The nidus is fed by only one of the main trunks of the middle cerebral artery (MCA). 3) Participation of deep perforators is uncommon. 4) They have two or more early draining veins showing their fistulous nature. 5) Preoperative embolization and radiosurgery have a low rate of permanent cure. CONCLUSIONS: These AVMs represent a surgical challenge due to their proximity to critical structures such as the MCA, insula, internal capsule, and speech and memory functions in the dominant hemisphere. Essential key points are the wide opening of the SF and proper differentiation between feeders and normal vessels. Although this location can seem daunting, SF AVMs carry no additional surgical risk if adequately managed.

The Role of 3D Tractography in Skull Base Surgery: Technological Advances, Feasibility, and Early Clinical Assessment with Anterior Skull Base Meningiomas.

Objective The aim of this study is to determine feasibility of incorporating three-dimensional (3D) tractography into routine skull base surgery planning and analyze our early clinical experience in a subset of anterior cranial base meningiomas (ACM). Methods Ninety-nine skull base endonasal and transcranial procedures were planned in 94 patients and retrospectively reviewed with a further analysis of the ACM subset. Main Outcome Measures (1) Automated generation of 3D tractography; (2) co-registration 3D tractography with computed tomography (CT), CT angiography (CTA), and magnetic resonance imaging (MRI); and (3) demonstration of real-time manipulation of 3D tractography intraoperatively. ACM subset: (1) pre- and postoperative cranial nerve function, (2) qualitative assessment of white matter tract preservation, and (3) frontal lobe fluid-attenuated inversion recovery (FLAIR) signal abnormality. Results Automated 3D tractography, with MRI, CT, and CTA overlay, was produced in all cases and was available intraoperatively. ACM subset : 8 (44%) procedures were performed via a ventral endoscopic endonasal approach (EEA) corridor and 12 (56%) via a dorsal anteromedial (DAM) transcranial corridor. Four cases (olfactory groove meningiomas) were managed with a combined, staged approach using ventral EEA and dorsal transcranial corridors. Average tumor volume reduction was 90.3 ± 15.0. Average FLAIR signal change was -30.9% ± 58.6. 11/12 (92%) patients (DAM subgroup) demonstrated preservation of, or improvement in, inferior fronto-occipital fasciculus volume. Functional cranial nerve recovery was 89% (all cases). Conclusion It is feasible to incorporate 3D tractography into the skull base surgical armamentarium. The utility of this tool in improving outcomes will require further study.

Microsurgical anatomy of the cranial nerve-centric triangles of the posterior cranial base: cadaveric and radiological anatomical study.

Tumors in the posterior fossa can be situated either dorsal and lateral, ventral and medial, or occupying both regions in relation to the cranial nerves, with the latter position being especially challenging. In an effort to organize neurovascular complexes contained within, anatomically based triangles have been proposed to serve as guiding landmarks for locating critical neurovascular structures. The objectives of this study were to: (1) provide a review of historical anatomically based vascular-centric triangles of the posterior fossa based on respective neurovascular complexes; (2) introduce a more organized alternative system of triangles with the conceptualization of a projection system from superficial to deep; and (3) propose and describe two new triangles of the posterior fossa: Petrous-Acousticofacial and Acousticofacial-Trigeminal. Five cadavers were studied. Neurovascular complexes were described with the use of anatomically guided cranial nerve-centric triangles, each of which was formed by cranial nerves, petrous bone, brainstem, tentorium, and superior petrosal vein. All triangles were measured and anatomical boundaries confirmed by neuronavigation. Two circumferential frameworks were created to correlate superficial and deep anatomy: (1) Outer circumference and (2) Inner circumference. Posterior fossa was divided into the following: (1) Superior complex-corresponds to the sub-asterional region, which was projected to the trigeminal nerve; (2) Middle complex-corresponds to the mastoid emissary vein foramen, which was projected to the facial and vestibulocochlear nerves; and (3) Inferior complex-corresponds to the posterior condylar canal, which projects to the lower cranial nerves. Neuronavigation confirmed these landmarks. Two new triangles were proposed: (1) The Petrous-Acousticofacial triangle, and (2) The Acousticofacial-Trigeminal triangle. Triangles provide a useful anatomical guide to the posterior fossa. We have introduced an organized schema, as well as proposed two new triangles, with the intent to minimize manipulation of neurovascular structures.

Minimally invasive trans-sulcal parafascicular surgical resection of cerebral tumors: translating anatomy to early clinical experience.

The minimally invasive port-based trans-sulcal parafascicular surgical corridor (TPSC) has incrementally evolved to provide a safe, feasible, and effective alternative to access subcortical and intraventricular pathologies. A detailed anatomical foundation is important in mitigating cortical and white matter tract injury with this corridor. Thus, the aims of this study are (1) to provide a detailed anatomical construct and overview of TPSCs and (2) to translate an anatomical framework to early clinical experience. Based on regional anatomical constraints, suitable parafascicular entry points were identified and described. Fiber tracts at both minimal and increased risks for each corridor were analyzed. TPSC-managed cases for metastatic or primary brain tumors were retrospectively reviewed. Adult patients 18 years or older with Karnofsky Performance Status (KPS) ≥ 70 were included. Subcortical brain metastases between 2 and 6 cm or primary brain tumors between 2 and 5 cm were included. Patient-specific corridors and trajectories were determined using MRI-tractography. Anatomy: The following TPSCs were described and translated to clinical practice: superior frontal, inferior frontal, inferior temporal, intraparietal, and postcentral sulci. Clinical: Eleven patients (5 males, 6 females) were included (mean age = 52 years). Seven tumors were metastatic, and 4 were primary. Gross total, near total, and subtotal resection was achieved in 7, 3, and 1 patient(s), respectively. Three patients developed intraoperative complications; all recovered from their intraoperative deficits and returned to baseline in 30 days. A detailed TPSC anatomical framework is critical in conducting safe and effective port-based surgical access. This review may represent one of the few early translational TPSC studies bridging anatomical data to clinical subcortical and intraventricular surgical practice.

The Evolution of Cerebral Language Localization: Historical Analysis and Current Trends.

Language localization has been an evolving concept over the past 150 years, with the emergence of several important yet conflicting ideologies. The classical theory, starting from the phrenologic work of Gall to the identification of specific regions of language function by Broca, Wernicke, and others, proposed that discrete subcomponents of language were organized into separate anatomic structural regions. The holism theory was postulated in an attempt to disclose that language function was instead attributed to a larger region of the cortex, in which cerebral regions may have the capability of assuming the function of damaged areas. However, this theory was largely abandoned in favor of discrete structural localizationist viewpoints. The subsequent cortical stimulatory work of Penfield led to the development of maps of localization, assigning an eloquent designation to specific regions. The expanding knowledge of cortical and subcortical anatomy allowed for the development of anatomically and functionally integrative language models. In particular, the dual stream model revisited the concept of regional interconnectivity and expanded the concept of eloquence. Advancements in cortical-subcortical stimulation, neurophysiologic monitoring, magnetic resonance diffusion tensor imaging/functional magnetic resonance imaging, awake neurosurgical technique, and knowledge gained by white matter tract anatomy and the Human Connectome Project, shed new light on the dynamic interconnectivity of the cerebrum. New studies are progressively opening doors to this paradigm, showing the dynamic and interdependent nature of language function. In this review, the evolution of language toward the evolving paradigm of dynamic language function and interconnectivity and its impact on shaping the neurosurgical paradigm are outlined.

Treatment and outcome in 12 cases of olfactory neuroblastoma at Mexico´s National Cancer Institute: A retrospective clinical analysis and literature review.

INTRODUCTION: Olfactory neuroblastoma (ONB) is a malignant neoplasm that arises from the upper nasal vault. OBJECTIVE: We present a retrospective case series and clinical analysis of 12 ONB cases. MATERIALS AND METHODS: Patients with ONB treated at Mexico´s National Cancer Institute between 2011 and 2018. RESULTS: The Kadish proportion of B, C, and D stage was 16%, 58%, or 25%, respectively. Hyams Grade 1, 2, or 3 was 25%, 50%, and 25%, respectively. The most common surgical approach was the craniofacial in 5 cases (42%), followed by the transfacial in 4 cases (33%), and the endonasal endoscopic approach in 3 cases (25%). Gross total resection was achieved in 8 patients (67%). Five patients (42%) underwent a second operation due to recurrent/progressive disease. The surgical complication rate was 8.3%. Progression-free survival was 41 months and the mean overall survival was 63.6 months. CONCLUSIONS: Surgical resection followed by radiotherapy, and chemotherapy for metastatic and recurrent disease provides the best outcome in terms of survival and recurrence. To the best of our knowledge, this is the first series of cases reported in Mexico.

ANTECEDENTES: El neuroblastoma olfatorio es una neoplasia maligna que se origina en la bóveda nasal superior. OBJETIVO: Presentar una serie de casos y un análisis clínico retrospectivo. MÉTODO: Pacientes con neuroblastoma olfatorio tratados en el Instituto Nacional de Cancerología, de México, entre 2011 y 2018. RESULTADOS: La proporción de Kadish en las etapas B, C y D fue del 16, el 58 y el 25%, respectivamente. Los grados 1, 2 y 3 de Hyams fueron el 25, el 50 y el 25%, respectivamente. El abordaje quirúrgico más frecuente fue el craneofacial, en cinco casos (42%), seguido del transfacial en cuatro (33%) y del abordaje endoscópico endonasal en tres (25%). La resección total macroscópica se logró en ocho pacientes (67%). Cinco pacientes (42%) se sometieron a una segunda operación debido a enfermedad recurrente o progresiva. La tasa de complicaciones quirúrgicas fue del 8,3%. La sobrevida libre de progresión fue de 41 meses y la supervivencia media global fue de 63,6 meses. CONCLUSIONES: La resección quirúrgica seguida de radioterapia y quimioterapia para la enfermedad metastásica y recurrente proporciona el mejor resultado en términos de supervivencia y recurrencia. Hasta donde sabemos, esta es la primera serie de casos reportados en México.

White Matter Governed Superior Frontal Sulcus Surgical Paradigm: A Radioanatomic Microsurgical Study-Part II.

BACKGROUND: Kocher's point (KP) and its variations have provided standard access to the frontal horn (FH) for over a century. Anatomic understanding of white matter tracts (WMTs) has evolved, now positioning us to better inform the optimal FH trajectory. OBJECTIVE: To (1) undertake a literature review analyzing entry points (EPs) to the FH; (2) introduce a purpose-built WMT-founded superior frontal sulcus parafascicular (SFSP)-EP also referred to as the Kassam-Monroy entry point (KM-EP); and (3) compare KM-EP with KP and variants with respect to WMTs. METHODS: (1) Literature review (PubMed database, 1892-2018): (a) stratification based on the corridor: i. ventricular catheter; ii. through-channel endoscopic; or iii. portal; (b) substratification based on intent: i. preoperatively planned or ii. intraoperative (postdural opening) for urgent ventricular drainage. (2) Anatomic comparisons of KM-EP, KP, and variants via (a) cadaveric dissections and (b) magnetic resonance-diffusion tensor imaging computational 3D modeling. RESULTS: A total of 31 studies met inclusion criteria: (a) 9 utilized KP coordinate (1 cm anterior to the coronal suture (y-axis) and 3 cm lateral of the midline (x-axis) approximated by the midpupillary line) and 22 EPs represented variations. All 31 traversed critical subcortical WMTs, specifically the frontal aslant tract, superior longitudinal fasciculus II, and inferior fronto-occipital fasciculus, whereas KM-EP (x = 2.3, y = 3.5) spares these WMTs. CONCLUSION: KP (x = 3, y = 1) conceived over a century ago, prior to awareness of WMTs, as well as its variants, anatomically place critical WMTs at risk. The KM-EP (x = 2.3, y = 3.5) is purpose built and founded on WMTs, representing anatomically safe access to the FH. Correlative clinical safety, which will be directly proportional to the size of the corridor, is yet to be established in prospective studies.

White Matter-Governed Superior Frontal Sulcus Surgical Paradigm: A Radioanatomic Microsurgical Study-Part I.

BACKGROUND: Frontal subcortical and intraventricular pathologies are traditionally accessed via transcortical or interhemispheric-transcallosal corridors. OBJECTIVE: To describe the microsurgical subcortical anatomy of the superior frontal sulcus (SFS) corridor. METHODS: Cadaveric dissections were undertaken and correlated with magnetic resonance imaging/diffusion-tensor imaging-Tractography. Surgical cases demonstrated clinical applicability. RESULTS: SFS was divided into the following divisions: proximal, precentral sulcus to coronal suture; middle, 3-cm anterior to coronal suture; and distal, middle division to the orbital crest. Anatomy was organized as layered circumferential rings projecting radially towards the ventricles: (1) outer ring: at the level of the SFS, the following lengths were measured: (A) precentral sulcus to coronal suture = 2.29 cm, (B) frontal bone projection of superior sagittal sinus (SSS) to SFS = 2.37 cm, (C) superior temporal line to SFS = 3.0 cm, and (D) orbital crest to distal part of SFS = 2.32 cm; and (2) inner ring: (a) medial to SFS, U-fibers, frontal aslant tract (FAT), superior longitudinal fasciculus I (SLF-I), and cingulum bundle, (b) lateral to SFS, U-fibers, (SLF-II), claustrocortical fibers (CCF), and inferior fronto-occipital fasciculus, and (c) intervening fibers, FAT, corona radiata, and CCF. The preferred SFS parafascicular entry point (SFSP-EP) also referred to as the Kassam-Monroy entry point (KM-EP) bisects the distance between the midpupillary line and the SSS and has the following coordinates: x = 2.3 cm (lateral to SSS), y ≥ 3.5 cm (anterior to CS), and z = parallel corona radiata and anterior limb of the internal capsule. CONCLUSION: SFS corridor can be divided into lateral, medial, and intervening white matter tract segments. Based on morphometric assessment, the optimal SFSP-EP is y ≥ 3.5 cm, x = 2.3 cm, and z = parallel to corona radiata and anterior limb of the internal capsule.

Initial Experience with Exoscopic-Based Intraoperative Indocyanine Green Fluorescence Video Angiography in Cerebrovascular Surgery: A Preliminary Case Series Showing Feasibility, Safety, and Next-Generation Handheld Form-Factor.

BACKGROUND: Native vessel patency and residual lesion are primary sources of morbidity in cerebrovascular surgery (CVS) that require real-time visualization to inform surgical judgment, as is available in endovascular procedures. Micro Doppler and microscopy-based indocyanine green (ICG) fluorescence are promising evolutions compared with intraoperative angiography (IA), and digital subtraction angiography (DSA) remains the gold standard. Exoscopic visualization in CVS is emerging; however, the feasibility of exoscopic-based ICG (ICG-E) for CVS has not yet been reported. To objective of the study was to provide initial experience with ICG-E video angiography in CVS. METHODS: Retrospective study in which 2 ICG-E form-factors (exoscopic-coupled or self-contained handheld imager) were used to determine native vessel patency and residual and compared with DSA. RESULTS: Eleven patients (8 aneurysms, 3 arteriovenous malformations [AVMs]) were included. ICG-E was feasible in all, providing real-time information leading to operative decisions affecting surgical judgment. For aneurysms, discordance of IA with ICG-E and DSA was 12%. In 1 patient, IA showed non-flow-restrictive branch stenosis; however, both ICG and DSA showed patency. All AVMs were fully obliterated, with 100% concordance among all modalities. ICG averaged 4.2 mg dose/run (1-4 doses/case); 1.25 mg was the lowest dose allowing visualization with no advantage with escalating dosages. There were no intraoperative/perioperative complications. CONCLUSIONS: In this preliminary study, ICG-E was safe and feasible, providing real-time visualization informing surgical decision making. The last 4 cases (2 aneurysms and 2 AVMs) evolved toward a portable handheld device, a readily accessible real-time modality providing contextual anatomic and flow visualization. Larger studies are needed to assess broader safety, dose escalation, and efficacy.

An Anatomically-Based Endoscopic Endonasal Model to Navigate the Anterior Ventral Skull Base.

BACKGROUND: Endoscopic endonasal approaches to access the sellar and parasellar regions are challenging in the face of anatomical variations or pathologic conditions. We propose an anatomically-based model including the orbitosellar line (OSL), critical oblique foramen line (COFL), and paramedial anterior line (PAL) facilitating safe, superficial-to-deep dissection triangulating upon the medial opticocarotid recess. METHODS: Five cadaveric heads were dissected to systematically expose the OSL, COFL, and PAL, illustrated with image guidance. Application of the coordinate system and a 6-step dissection sequence is described. RESULTS: The coordinate system consists of 1) the OSL, connecting a) the anterior orbital point, junction of the anterior buttress of the middle turbinate with the agger nasi region, located 34.3 ± 0.9 mm above the intersection of the vertical plane of the lacrimal crest, and the orthogonal plane of the maxillo-ethmoidal suture; b) the posterior orbital point, junction of the optic canal with the lamina papyracea, located 4 ± 0.7 mm below the posterior ethmoidal artery; and c) the medial opticocarotid recess; 2) COFL (15 ± 2.8 mm), connecting the palatovaginal canal, vidian canal, and foramen rotundum; and 3) PAL (39 ± 0.06 mm), connecting the vidian canal with the posterior ethmoidal artery. CONCLUSIONS: OSL, COFL, and PAL form an anatomically-based model for the systematic exposure when accessing the parasellar and sellar regions. Preliminary anatomical data suggest that this model may be of value when normal anatomy is distorted by pathology or anatomic variations.

Awake Surgical Management of Third Ventricular Tumors: A Preliminary Safety, Feasibility, and Clinical Applications Study.

BACKGROUND: Endoscopic and microneurosurgical approaches to third ventricular lesions are commonly performed under general anesthesia. OBJECTIVE: To report our initial experience with awake transsulcal parafascicular corridor surgery (TPCS) of the third ventricle and its safety, feasibility, and limitations. METHODS: A total of 12 cases are reviewed: 6 colloid cysts, 2 central neurocytomas, 1 papillary craniopharyngioma, 1 basal ganglia glioblastoma, 1 thalamic glioblastoma, and 1 ependymal cyst. Lesions were approached using TPCS through the superior frontal sulcus. Pre-, intra-, and postoperative neurocognitive (NC) testing were performed on all patients. RESULTS: No cases required conversion to general anesthesia. Awake anesthesia changed intraoperative management in 4/12 cases with intraoperative cognitive changes that required port re-positioning; 3/4 recovered. Average length of stay (LOS) was 6.1 d ± 6.6. Excluding 3 outliers who had preoperative NC impairment, the average LOS was 2.5 d ± 1.2. Average operative time was 3.00 h ± 0.44. Average awake anesthesia time was 5.05 h ± 0.54. There were no mortalities. CONCLUSION: This report demonstrated the feasibility and safety of awake third ventricular surgery, and was not limited by pathology, size, or vascularity. The most significant factor impacting LOS was preoperative NC deficit. The most significant risk factor predicting a permanent NC deficit was preoperative 2/3 domain impairment combined with radiologic evidence of invasion of limbic structures - defined as a "NC resilience/reserve" in our surgical algorithm. Larger efficacy studies will be required to demonstrate the validity of the algorithm and impact on long-term cognitive outcomes, as well as generalizability of awake TPCS for third ventricular surgery.

Gelatin Paste as an Alternative Cost-Effective Hemostatic Agent in Cranial Surgery: Doing More with Less.

OBJECTIVE: To present an alternative cost-effective hemostatic agent (HA) for cranial surgery and to describe the technique to produce it. METHODS: This HA has been used in 3 reference centers over the last year during 230 procedures, including different types of pathology, such as skull base, oncology, vascular, and trauma, either for endoscopic or open approaches. This agent was made from a low-cost and worldwide-available gelatin foam which was mixed with saline solution in 2 syringes and connected by a 3-way stopcock, making a useful hemostatic paste. RESULTS: The cost was 16 and 28 times less than SURGIFLO and FLOSEAL, respectively. The mean time to prepare the mix was 4 minutes. It was very effective for venous and low-flow bleeding. CONCLUSIONS: The presented technique offers a reliable and cost-effective way of achieving hemostasis in cranial surgery, therefore allowing hospitals with limited resources to perform advanced procedures in a safer way.

Microsurgical Anatomy of the Vertical Rami of the Superior Longitudinal Fasciculus: An Intraparietal Sulcus Dissection Study.

BACKGROUND: A number of vertical prolongations of the superior longitudinal fasciculus, which we refer to as the vertical rami (Vr), arise at the level of the supramarginal gyrus, directed vertically toward the parietal lobe. OBJECTIVE: To provide the first published complete description of the white matter tracts (WMT) of the Vr, their relationship to the intraparietal and parieto-occipital sulci (IPS-POS complex), and their importance in neurosurgical approaches to the parietal lobe. METHODS: Subcortical dissections of the Vr and WMT of the IPS were performed. Findings were correlated with a virtual dissection using high-resolution diffusion tensor imaging (DTI) tractography data derived from the Human Connectome Project. Example planning of a transparietal, transsulcal operative corridor is demonstrated using an integrated neuronavigation and optical platform. RESULTS: The Vr were shown to contain component fibers of the superior longitudinal fasciculus (SLF)-II and SLF-III, with contributions from the middle longitudinal fasciculus merging into the medial bank of the IPS. The anatomic findings correlated well with DTI tractography. The line extending from the lateral extent of the POS to the IPS marks an ideal sulcal entry point that we have termed the IPS-POS Kassam-Monroy (KM) Point, which can be used to permit a safe parafascicular surgical trajectory to the trigone. CONCLUSION: The Vr are a newly conceptualized group of tracts merging along the banks of the IPS, mediating connectivity between the parietal lobe and dorsal stream/SLF. We suggest a refined surgical trajectory to the ventricular atrium utilizing the posterior third of the IPS, at or posterior to the IPS-POS Point, in order to mitigate risk to the Vr and its considerable potential for postsurgical morbidity.

Cervical Intramedullary Schwannoma: Case Report and Review of the Literature.

Cervical intramedullary schwannomas are extraordinarily rare. Gross total resection is the best therapeutic option for these types of tumors. Although rare, intramedullary schwannomas should be considered as a differential diagnosis of intramedullary lesions since a good prognosis can be guaranteed to the majority of these patients. We present a case of a cervical intramedullary schwannoma surgically treated in a 19-year-old male patient who initially presented with motor neuron disease.

Reanalyzing the "far medial" (transcondylar-transtubercular) approach based on three anatomical vectors: the ventral posterolateral corridor.

Endoscopic endonasal access to the jugular foramen and occipital condyle - the transcondylar-transtubercular approach - is anatomically complex and requires detailed knowledge of the relative position of critical neurovascular structures, in order to avoid inadvertent injury and resultant complications. However, access to this region can be confusing as the orientation and relationships of osseous, vascular, and neural structures are very much different from traditional dorsal approaches. This review aims at providing an organizational construct for a more understandable framework in accessing the transcondylar-transtubercular window. The region can be conceptualized using a three-vector coordinate system: vector 1 represents a dorsal or ventral corridor, vector 2 represents the outer and inner circumferential anatomical limits; in an "onion-skin" fashion, key osseous, vascular, and neural landmarks are organized based on a 360-degree skull base model, and vector 3 represents the final core or target of the surgical corridor. The creation of an organized "global-positioning system" may better guide the surgeon in accessing the far-medial transcondylar-transtubercular region, and related pathologies, and help understand the surgical limits to the occipital condyle and jugular foramen - the ventral posterolateral corridor - via the endoscopic endonasal approach.

Lactate dehydrogenase as a prognostic marker in neoplastic meningitis.

This study aimed to establish the prognostic utility of lactate dehydrogenase (LDH) levels in the cerebrospinal fluid (CSF) of patients with neoplastic meningitis (NM). Patients with a confirmed diagnosis of NM at a cancer referral center were included. Data on demographic and oncological background, clinical symptoms, diagnostic tests, treatment, and survival were analyzed. In total, 119 patients were included, 74% of whom were females. The mean age was 44.2 years at the time of cancer diagnosis and 46.6 years at the time between NM diagnosis. Primary cancers were mostly breast cancer, lung cancer, or hematologic malignancies. The mean Karnofsky performance score (KPS) was 65. Frequent clinical symptoms were visual complaints, headache, cranial neuropathy, focal weakness, and decreased awareness. Diagnosis was made based on clinical symptoms, cytological CSF analysis results, and/or magnetic resonance imaging findings. The median overall survival (OS) was 4 months (95% CI 2.48-5.52). Prognostic variables associated with a better OS were hematopoietic malignancies, KPS ≥ 70, absence of meningeal signs, receiving any form of treatment, normal CSF glucose levels, and normal CSF LDH levels. After bivariate analysis, high LDH in the CSF remained statistically significant as a poor prognostic indicator. The LDH level is a useful parameter to assess the prognosis of patients with NM. Other factors associated with the prognosis of these patients were tumor type, CSF glucose levels, performance status, and receiving any form of treatment.