Microsurgical anatomy and approaches to thalamic gliomas. Part 2: Maximal safe resection of thalamic gliomas improves outcomes. A single-center experience.

OBJECTIVE: As presented in Part 1 of this series, thalamic gliomas (TGs) are deep-seated, difficult-to-access tumors surrounded by vital neurovascular structures. Given their high operative morbidity, TGs have historically been considered inoperable lesions. Although maximal safe resection (MSR) has become the treatment standard for lobar and even deep-seated mediobasal temporal and insular gliomas, the eloquent location of TGs has precluded this management strategy, with biopsy and adjuvant treatment being the mainstay. The authors hypothesized that MSR can be achieved with low morbidity and mortality for TGs, thus resulting in improved outcomes. METHODS: A retrospective single-center study was performed on all TG patients from 2006 to 2020. Clinical, imaging, and pathology reports were obtained. Univariate and multivariate analyses were performed to determine prognostic variables. Case examples illustrate various approaches and the rationale for staging resections of more complex TGs. RESULTS: A total of 42 patients (26 males, 16 females), among them 12 pediatric (29%) cases, were included. Their mean age was 36.0 ± 21.4 (median 30, range 3-73) years. The median maximal tumor diameter was 45 (range 19-70) mm. Eighteen patients (43%) had a prior stereotactic needle tumor biopsy, with the ultimate diagnosis changed for 7 patients (39%) following microsurgical resection. The most common surgical approaches were transtemporal (29%), anterior interhemispheric transcallosal (29%), and superior parietal lobule (25%). Overall, the combined subtotal and gross-total resection rate was 95% (n = 40). Low-grade gliomas (LGGs; grades I and II) comprised one-third of the group, whereas half of the patients had glioblastoma multiforme. There were no operative mortalities. Although temporary postoperative motor deficits were observed in 12 patients (28.6%), all improved during the early postoperative period except 1 (2.4%), who had mild residual hemiparesis. Two patients required CSF diversion for hydrocephalus. The 2-year overall survival rate was 90% for LGG patients and 15% for high-grade glioma (HGG) patients. Multivariate analysis revealed that histological grade, age, and extent of resection were independent prognostic factors associated with survival. CONCLUSIONS: Management of TGs is challenging, with resection avoided by many, if not most, neurosurgeons, especially for HGGs. The results reported here demonstrate improved outcomes with resection, particularly in younger LGG patients. The authors therefore advocate for MSR for a select cohort of TG patients using carefully planned surgical approaches, contemporary intraoperative adjuncts, and meticulous microsurgical techniques.

Microsurgical anatomy and approaches to thalamic gliomas. Part 1: A cartography guide for navigating to the thalamus. Integrating 3D model rendering with anatomical dissections.

OBJECTIVE: The selection of appropriate microsurgical approaches to treat thalamic pathologies is currently largely subjective. The objective of this study was to provide a structured cartography map for surgical navigation to treat gliomas involving different surfaces of the thalamus. METHODS: Fifteen formalin-fixed, silicone-injected cadavers (30 sides) were dissected, and 10 adult brain specimens (20 sides) were used to illustrate thalamic microsurgical anatomy using the Klingler fiber dissection technique. Exposures and trajectories for the six most common microsurgical approaches were depicted using MR data from healthy subjects converted into surface-rendered 3D virtual brain models. Additionally, thalamic surfaces exposed with all six approaches were color mapped on the virtual 3D model and compared side-by-side in 360° views with previously reported microsurgical approaches. These 3D models were then used in conjunction with topographic data to guide cadaveric dissection steps. RESULTS: There are two general surgical routes to thalamic lesions: the subarachnoid transcisternal and transcortical routes. The transcisternal route consists of the following three approaches: 1) anterior interhemispheric transcallosal approach, which exposes the anterior and superior thalamus; 2) posterior interhemispheric transcallosal approach, which exposes the posterosuperior thalamus; and 3) supracerebellar infratentorial approach, which exposes the posteromedial cisternal thalamus and can be extended laterally to approach the posterolateral thalamus by cutting the tentorium. The three transcortical approaches are the 1) superior parietal lobule approach, which exposes the posterosuperior thalamus and is particularly advantageous in the setting of hydrocephalus; 2) transtemporal gyrus approach, which exposes the inferolateral thalamus; and 3) transsylvian transinsular approach, which exposes the lateral thalamus (slightly more superiorly and posteriorly) and is advantageous for pathologies extending laterally into the peduncle, lenticular nucleus, or insula. CONCLUSIONS: Microsurgical approaches to thalamic gliomas continue to be challenging. Nonetheless, safe and effective cisternal, ventricular, and cortical corridors can be developed with thoughtful planning, anatomical understanding, and knowledge of the advantages, risks, and limitations of each approach. In some cases, it is wise to combine these approaches with staged procedures, as the authors demonstrate in Part 2. In Part 1 of this two-part series, they discuss thalamic microsurgical anatomy and illustrate the trajectory and exposures of all six approaches to guide decision-making. Part 2 discusses their thalamic glioma microsurgical case series, which utilizes these microsurgical approaches.

Narrative review of patient-specific 3D visualization and reality technologies in skull base neurosurgery: enhancements in surgical training, planning, and navigation.

Recent advances in medical imaging, computer vision, 3-dimensional (3D) modeling, and artificial intelligence (AI) integrated technologies paved the way for generating patient-specific, realistic 3D visualization of pathological anatomy in neurosurgical conditions. Immersive surgical simulations through augmented reality (AR), virtual reality (VR), mixed reality (MxR), extended reality (XR), and 3D printing applications further increased their utilization in current surgical practice and training. This narrative review investigates state-of-the-art studies, the limitations of these technologies, and future directions for them in the field of skull base surgery. We begin with a methodology summary to create accurate 3D models customized for each patient by combining several imaging modalities. Then, we explore how these models are employed in surgical planning simulations and real-time navigation systems in surgical procedures involving the anterior, middle, and posterior cranial skull bases, including endoscopic and open microsurgical operations. We also evaluate their influence on surgical decision-making, performance, and education. Accumulating evidence demonstrates that these technologies can enhance the visibility of the neuroanatomical structures situated at the cranial base and assist surgeons in preoperative planning and intraoperative navigation, thus showing great potential to improve surgical results and reduce complications. Maximum effectiveness can be achieved in approach selection, patient positioning, craniotomy placement, anti-target avoidance, and comprehension of spatial interrelationships of neurovascular structures. Finally, we present the obstacles and possible future paths for the broader implementation of these groundbreaking methods in neurosurgery, highlighting the importance of ongoing technological advancements and interdisciplinary collaboration to improve the accuracy and usefulness of 3D visualization and reality technologies in skull base surgeries.

Molecular Subgrouping Based on Immunohistochemistry in Medulloblastoma: a Single-Center Experience.

AIM: Medulloblastomas (MBs) are the most commonly observed malignant brain tumors affecting children; they can be classified into molecular subgroups based on the 2016 and 2021 WHO classifications, as WNT-activated, SHH-activated and TP53-wild type, SHH-activated and TP53-mutant, and non-WNT/non-SHH. However, the molecular methods to determine these subgroups are not easily accessible for routine testing as they are expensive. Here, we investigated the efficacy of immunohistochemical methods to determine molecular subgroups and prognostic predictions of MB. MATERIAL AND METHODS: ß-catenin, GAB1, YAP1, filamin A and p53 were immunohistochemically stained, and MYC and MYCN fluorescent in situ hybridization (FISH) procedures were applied to 218 cases in our series. RESULTS: Based on the histomorphological characteristics of the cases, 67.9% were deemed classic MB; 15.6% as desmoplastic/nodular medulloblastoma (DNMB); 12.8% as large cell/anaplastic (LC/A) MB; 3.7% as medulloblastoma with extensive nodularity (MBEN). Molecular characteristics revealed that 50.5% had non-WNT/non-SHH; 33.9% had SHH-activated and TP53-wildtype; 8.7% had WNT-activated; 6.9% had SHH-activated and TP53-mutant. According to the survival curves, LC/A MBs or non-WNT/non-SHH tumors showed the worst prognosis, whereas DNMBs and WNT-activated tumors showed the best prognosis. Classic MBs or SHH-activated tumors showed a moderate course. MYCN amplification was found to act as an independent poor prognostic factor in the study. CONCLUSION: The distribution of histological subtypes and molecular subgroups, amplification rates, and prognostic data obtained through immunohistochemical methods in our study were consistent with those reported in the literature. It was therefore hypothesized that the determination of molecular subgroups by immunohistochemical methods can be useful in daily diagnostic practice, especially in centers with limited access to molecular techniques.

Arteriovenous malformations in the cerebellopontine angle: assessment of the "backdoor resection" technique and microsurgical results in 38 patients.

OBJECTIVE: Posterior fossa arteriovenous malformations (AVMs) represent 7% to 15% of all intracranial AVMs and are associated with an increased risk of hemorrhage, morbidity, and mortality compared with supratentorial AVMs, thus prompting urgent and definitive treatment. Cerebellopontine angle (CPA) AVMs are a unique group of posterior fossa AVMs incorporating characteristics of brainstem and cerebellar lesions, which are particularly amenable to microsurgical resection. This study reports the clinical, radiological, operative, and outcome features of patients with CPA AVMs in a large cohort. METHODS: The authors conducted a single-surgeon, 2-institution retrospective cohort study of all consecutive patients with CPA AVMs treated with microsurgical resection during a 25-year period. RESULTS: CPA AVMs represented 22% (38 of 176) of all infratentorial AVMs resected by the senior author. Overall, 38 patients (22 [58%] male and 16 [42%] female) met the study inclusion criteria and were analyzed. Most patients presented with hemorrhage (n = 29, 76%). The median age at surgery was 56 (range 6-82) years. Subtypes included 22 (58%) petrosal cerebellar AVMs, 11 (29%) lateral pontine AVMs, and 5 (13%) AVMs involving both the brainstem and cerebellum. Most AVM niduses were small (< 3 cm; n = 35, 92%) and compact (n = 31, 82%). Fourteen (37%) patients harbored flow-related aneurysms. Twenty (53%) patients underwent preoperative embolization. Complete angiographic obliteration was achieved with microsurgery in 35 (92%) patients. Five (13%) patients with poor neurological conditions at presentation died before hospital discharge. Of the 7 (18%) patients with new postoperative neurological deficits, 5 had transient deficits. The median (interquartile range) follow-up was 1.7 (0.5-3.2) years; 32 (84%) patients were alive at last follow-up, and 30 (79%) had achieved a favorable neurological outcome (modified Rankin Scale [mRS] score 0-2). The only independent predictor of unfavorable postoperative outcome (mRS score 3-6) was the preoperative mRS score (p = 0.002). CONCLUSIONS: CPA AVMs are unique posterior fossa lesions, including petrosal cerebellar and lateral pontine AVMs. The "backdoor resection" technique provides a safe and efficient strategy with high obliteration rates and a low risk of treatment-related morbidity. Microsurgical resection should be considered the frontline treatment for most CPA AVMs, except for those with a significant diffuse brainstem component.

Relative Cortical Atrophy Index as a Strong Predictor of Recurrence After Surgery for Chronic Subdural Hematoma.

BACKGROUND AND OBJECTIVES: Chronic subdural hematoma (CSDH) presents significant management challenges in neurosurgical practice, with recurrence being a notable postoperative consideration. This study aimed to evaluate the Relative Cortical Atrophy (RCA) Index as a predictor of recurrence after CSDH surgery. METHODS: A retrospective analysis was conducted on 98 patients who underwent surgical evacuation for unilateral CSDH. The RCA Index was calculated using pre- and postoperative cranial imaging, correlating it with patient demographics, hematoma characteristics, and recurrence. Inter-rater reliability among measurements by 4 independent physicians was assessed using the intraclass correlation coefficient (ICC). Correlation and regression analyses were performed to identify the correlation of the RCA Index with other factors and their potential predicting power of CSDH recurrence, respectively. RESULTS: The study population had a mean age of 74.1 (11.9) years, with a 23.5% (23 patients) recurrence rate of CSDH. The ICC analysis showed excellent inter-rater reliability for RCA Index measurements (ICC: 0.998, 95% CI: 0.997-0.998, P < .001). A higher preoperative RCA Index was significantly associated with recurrence (0.215 [0.031] in the recurrent group vs 0.125 [0.034] in the nonrecurrent group, P < .001). The preoperative RCA Index highly correlated with the postoperative RCA Index (Pearson's correlation: 0.918, P < .001), and there was only a small (average: 0.005) but significant increase in the RCA Index of the unaffected hemisphere after surgery (P = .01).The preoperative RCA Index positively correlated with age, preoperative SDH thickness and volume, and recurrence. A RCA Index cutoff value of 0.165 predicted CSDH recurrence with high sensitivity (95.6%) and specificity (93.3%) (area under the curve = 0.97, 95% CI: 0.93-1). CONCLUSION: The RCA Index is a simple yet robust predictor of CSDH recurrence. Incorporating this measure into the preoperative assessment may enhance surgical planning and postoperative management, potentially reducing recurrence rates.

Quantitative assessment and objective improvement of the accuracy of neurosurgical planning through digital patient-specific 3D models.

Objective: Neurosurgical patient-specific 3D models have been shown to facilitate learning, enhance planning skills and improve surgical results. However, there is limited data on the objective validation of these models. Here, we aim to investigate their potential for improving the accuracy of surgical planning process of the neurosurgery residents and their usage as a surgical planning skill assessment tool. Methods: A patient-specific 3D digital model of parasagittal meningioma case was constructed. Participants were invited to plan the incision and craniotomy first after the conventional planning session with MRI, and then with 3D model. A feedback survey was performed at the end of the session. Quantitative metrics were used to assess the performance of the participants in a double-blind fashion. Results: A total of 38 neurosurgical residents and interns participated in this study. For estimated tumor projection on scalp, percent tumor coverage increased (66.4 ± 26.2%-77.2 ± 17.4%, p = 0.026), excess coverage decreased (2,232 ± 1,322 mm2-1,662 ± 956 mm2, p = 0.019); and craniotomy margin deviation from acceptable the standard was reduced (57.3 ± 24.0 mm-47.2 ± 19.8 mm, p = 0.024) after training with 3D model. For linear skin incision, deviation from tumor epicenter significantly reduced from 16.3 ± 9.6 mm-8.3 ± 7.9 mm after training with 3D model only in residents (p = 0.02). The participants scored realism, performance, usefulness, and practicality of the digital 3D models very highly. Conclusion: This study provides evidence that patient-specific digital 3D models can be used as educational materials to objectively improve the surgical planning accuracy of neurosurgical residents and to quantitatively assess their surgical planning skills through various surgical scenarios.

Repeat endoscopic endonasal transsphenoidal surgery for residual or recurrent Cushing's disease: safety, feasibility, and success.

PURPOSE: The success and outcomes of repeat endoscopic transsphenoidal surgery (ETS) for residual or recurrent Cushing's disease (CD) are underreported in the literature. This study aims to address this gap by assessing the safety, feasibility, and efficacy of repeat ETS in these patients. METHODS: A retrospective analysis was conducted on 56 patients who underwent a total of 65 repeat ETS performed by a single neurosurgeon between January 2006 and December 2020. Data including demographic, clinical, laboratory, radiological, and operative details were collected from electronic medical records. Logistic regression was utilized to identify potential predictors associated with sustained remission. RESULTS: Among the cases, 40 (61.5%) had previously undergone microscopic surgery, while 25 (38.5%) had prior endoscopic procedures. Remission was achieved in 47 (83.9%) patients after the first repeat ETS, with an additional 9 (16.1%) achieving remission after the second repeat procedure. During an average follow-up period of 97.25 months, the recurrence rate post repeat surgery was 6.38%. Sustained remission was achieved in 48 patients (85.7%), with 44 after the first repeat ETS and 4 following the second repeat ETS. Complications included transient diabetes insipidus (DI) in 5 (7.6%) patients, permanent (DI) in 2 (3%) patients, and one case (1.5%) of panhypopituitarism. Three patients (4.6%) experienced rhinorrhea necessitating reoperation. A serum cortisol level > 5 µg/dL on postoperative day 1 was associated with a reduced likelihood of sustained remission. CONCLUSION: Repeat ETS is a safe and effective treatment option for residual or recurrent CD with satisfactory remission rates and low rates of complications.

Posterior Interhemispheric-Transtentorial Approach for Resection of an Arteriovenous Malformation of the Superior Medullary Velum and Fourth Ventricle: 2-Dimensional Operative Video.

Brain arteriovenous malformations (AVMs) of the fourth ventricle represent a rare subtype associated with an aggressive natural course.1,2 In this case, a woman in her early 50s presented with dizziness. An AVM was diagnosed in the left superior cerebellar peduncle extending into the fourth ventricle. The AVM was supplied by superior cerebellar artery branches and classified as a Spetzler-Martin grade III and a Lawton-Young grade III, with a supplemented grade of 6.3,4 Being a single case report, institutional review board approval was not needed. Patient consent was obtained. The lesion was accessed through a torcular craniotomy and posterior interhemispheric-transtentorial approach, employing gravity to naturally retract the parietooccipital lobe.5-7 Dissection continued into the quadrigeminal and ambient cisterns, where the tentorium was incised parallelling the straight sinus to reach the superior vermis. Partial resection of the lingual and central lobules of the vermis facilitated access to the superior medullary velum. The superior cerebellar artery feeders were divided and followed to the superior cerebellar peduncle and through the superior medullary vellum. A vertical incision in the superior medullary velum facilitated entry into the fourth ventricle, where the AVM nidus was dissected circumferentially and resected en bloc. Intraoperative indocyanine green videoangiography and postoperative digital subtraction angiography confirmed complete obliteration of the AVM. After surgery, the patient experienced mild ataxia, but motor symptoms greatly improved during 3-month follow-up. This video illustrates resection of a complex fourth ventricular AVM through a posterior interhemispheric-transtentorial approach, highlighting pivotal considerations of patient positioning and approach selection to optimize treatment outcome for complex posterior fossa AVM resection.

Duraplasty with autologous cervical fascia in pediatric posterior fossa tumor surgery: a single-center experience with 214 cases.

PURPOSE: Posterior fossa surgeries for pediatric tumors pose challenges in achieving optimal dural repair and duraplasty is usually required. Autografts, allografts, xenografts, and synthetic substitutes can be used for duraplasty. Autologous cervical fascia can be a safe and reliable graft option for duraplasty after posterior fossa surgeries. This study aims to investigate the outcomes of duraplasty with autologous cervical fascial graft in children after posterior fossa surgery for pediatric brain tumors. METHODS: Pediatric patients with posterior fossa tumor who underwent surgery between March 2001 and August 2022 were retrospectively reviewed. Data on demographics, preoperative symptoms, diagnosis, tumor characteristics, hydrocephalus history, and postoperative complications, including cerebrospinal fluid (CSF) leakage, pseudomeningocele, and meningitis were collected. Logistic regression analysis was performed to explore risk factors for postoperative complications. RESULTS: Patient cohort included 214 patients. Autologous cervical fascia was used in all patients for duraplasty. Mean age was 7.9 ± 5.3 years. Fifty-seven patients (26.6%) had preoperative hydrocephalus and 14 patients (6.5%) received VPS or EVD perioperatively. Postoperative hydrocephalus was present in 31 patients (14.5%). Rates of CSF leak, pseudomeningocele, and meningitis were 4.2%, 2.8%, and 4.2% respectively. Logistic regression analysis revealed that postoperative EVD and VPS placement were the factors associated with postoperative complications. CONCLUSION: Autologous cervical fascia is a safe and reliable option for duraplasty with minimal risk of postoperative complications. The straightforward surgical technique and with no additional cost for harvesting the graft renders autologous cervical fascia a favorable alternative for resource-limited countries or surgical settings.

Angiographic measurement of the superficial temporal artery for potential use in cerebral bypass surgery: a combined radiological and cadaveric study.

PURPOSE: This study aims to investigate the microsurgical anatomy of the superficial temporal artery (STA), explore the relationship between STA length and lumen diameter, and develop a reliable radiologic method for selecting STA segments for bypass surgery. METHODS: This study used 10 cadaveric dissections (20 STAs, both sides) and 20 retrospective radiological examinations (40 STAs, both sides), employing curved multiplanar reformation and flow color lookup table (CLUT) DICOM processing. Measurements included vessel lumen diameters and luminal cross-sectional thicknesses 3 mm proximal to the STA bifurcation, 3 mm distal to the frontal branch, 5 cm distal to the frontal branch, 3 mm distal to the parietal branch, and 5 cm distal to the parietal branch. The distance between the STA bifurcation and the superior zygomatic border (SZB) was also measured. In our analysis, descriptive statistics encompassed mean, standard deviation (SD), standard error, minimum and maximum values, and distributions. Comparative statistics were performed using Student's t-test, with statistical significance set at p < 0.05. RESULTS: There were no statistically significant differences between STA measurements of bifurcation distances (p = 0.88) and lumen diameters (p = 0.46) between cadavers and radiological measures. However, lumen thicknesses were larger in frontal branches than parietal branches at the seventh and eighth centimeter (p = 0.012, p = 0.039). Branches became thinner distally from the zygoma in both cadavers and radiological image measurements. CONCLUSION: The CLUT DICOM processing radiological measures provided the high-precision required to enable pre-surgical vessel selection for extracranial-intracranial bypass. The results show that STA vessel luminal diameters are sufficient (> 1 mm) for bypass surgery in the first 9 cm but gradually decrease after that. Also shown is that the choice of frontal versus parietal branches depends on individual anatomical features; therefore, careful preoperative radiological examination is critical.

Interactive microsurgical anatomy education using photogrammetry 3D models and an augmented reality cube.

OBJECTIVE: This study sought to assess the use of an augmented reality (AR) tool for neurosurgical anatomical education. METHODS: Three-dimensional models were created using advanced photogrammetry and registered onto a handheld AR foam cube imprinted with scannable quick response codes. A perspective analysis of the cube anatomical system was performed by loading a 3D photogrammetry model over a motorized turntable to analyze changes in the surgical window area according to the horizontal rotation. The use of the cube as an intraoperative reference guide for surgical trainees was tested during cadaveric dissection exercises. Neurosurgery trainees from international programs located in Ankara, Turkey; San Salvador, El Salvador; and Moshi, Tanzania, interacted with and assessed the 3D models and AR cube system and then completed a 17-item graded user experience survey. RESULTS: Seven photogrammetry 3D models were created and imported to the cube. Horizontal turntable rotation of the cube translated to measurable and realistic perspective changes in the surgical window area. The combined 3D models and cube system were used to engage trainees during cadaveric dissections, with satisfactory user experience. Thirty-five individuals (20 from Turkey, 10 from El Salvador, and 5 from Tanzania) agreed that the cube system could enhance the learning experience for neurosurgical anatomy. CONCLUSIONS: The AR cube combines tactile and visual sensations with high-resolution 3D models of cadaveric dissections. Inexpensive and lightweight, the cube can be effectively implemented to allow independent co-visualization of anatomical dissection and can potentially supplement neurosurgical education.

Infragalenic triangle as a gateway to dorsal midbrain and posteromedial thalamic lesions: descriptive and quantitative analysis of microsurgical anatomy.

OBJECTIVE: Anatomical triangles provide neurosurgeons with the specificity required to access deep targets, supplementing more general instructions, such as craniotomy and approach. The infragalenic triangle (IGT), bordered by the basal vein of Rosenthal (BVR), precentral cerebellar vein (PCV), and the quadrangular lobule of the cerebellum, is one of a system of anatomical triangles recently introduced to guide dissection to brainstem cavernous malformations and has not been described in detail. This study aimed to quantitatively analyze the anatomical parameters of the IGT and present key nuances for its microsurgical use. METHODS: A midline supracerebellar infratentorial (SCIT) approach through a torcular craniotomy was performed on 5 cadaveric heads, and the IGT was identified in each specimen bilaterally. Anatomical measurements were obtained with point coordinates collected using neuronavigation. Three cadaveric brains were used to illustrate relevant brainstem anatomy, and 3D virtual modeling was used to simulate various perspectives of the IGT through different approach angles. In addition, 2 illustrative surgical cases are presented. RESULTS: The longest edge of the IGT was the lateral edge formed by the BVR (mean ± SD length 19.1 ± 2.3 mm), and the shortest edge was the medial edge formed by the PCV (13.9 ± 3.6 mm). The mean surface area of the IGT was 110 ± 34.2 mm2 in the standard exposure. Full expansion of all 3 edges (arachnoid dissection, mobilization, and retraction) resulted in a mean area of 226.0 ± 48.8 mm2 and a 2.5-times increase in surface area exposure of deep structures (e.g., brainstem and thalamus). Thus, almost the entire tectal plate and its relevant safe entry zones can be exposed through an expanded unilateral IGT except for the contralateral inferior colliculus, access to which is usually hindered by PCV tributaries. Exposure of bilateral IGTs may be required to resect larger midline lesions to increase surgical maneuverability or to access the contralateral pulvinar. CONCLUSIONS: The IGT provides a safe access route to the dorsal midbrain and reliable intraoperative guidance in the deep and complex anatomy of the posterior tentorial incisura. Its potential for expansion makes it a versatile anatomical corridor not only for intrinsic brainstem lesions but also for tumors and vascular malformations of the pineal region, dorsal midbrain, and posteromedial thalamus.

Applications of enhanced recovery after surgery protocols for unruptured anterior circulation aneurysms in tertiary-level healthcare institutions: a national study.

OBJECTIVE: Enhanced recovery after surgery (ERAS) protocols are standardized perioperative care that reduce patients' stress response during hospitalization and improve hospitalization time, complication rates, costs, and readmission rates. This study aimed to investigate the application rate of protocols for elective craniotomy in the surgery of unruptured anterior circulation aneurysms (AnCAs) at tertiary-level healthcare (TLH) institutions in Türkiye and its effect on the outcomes of the patients. METHODS: An electronic survey was sent to all Turkish TLH institutions (n = 127) between May and June 2023. The number of institutions participating in the survey was 38 (30%). The institutions were subdivided according to three main factors: institution type (university hospital [UH] vs training and research hospital [TRH]), annual case volume (low [≤ 20 aneurysms] vs high [> 20 aneurysms]), and institution accreditation status (accredited vs nonaccredited). RESULTS: Overall, 55.3% (n = 21) of the institutions participating in the study were UHs. The rates of those that were accredited and had a high case volume were 55.3% (n = 21) and 31.6% (n = 12), respectively. It was determined that the accredited clinics applied preoperative protocols at a higher rate (p = 0.050), and the length of stay in the postoperative period was shorter in the clinics that used the intraoperative protocols (p = 0.014). CONCLUSIONS: The length of stay in the postoperative period is lower in TLH institutions in Türkiye that highly implement intraoperative protocols. Furthermore, this is the first study in the literature evaluating protocols for elective craniotomy in unruptured AnCAs.

Clinical Significance of Pneumocephalus in Pediatric Mild Traumatic Brain Injury.

OBJECTIVES: Mild traumatic brain injury (mTBI) comprises most (70%-90%) of all pediatric head trauma cases seeking emergency care. Although most mTBI cases have normal initial head computed tomography scan, a considerable portion of the cases have intracranial imaging abnormalities on computed tomography scan. Whereas other intracranial pathological findings have been extensively studied, little is known about the clinical significance of pneumocephalus in pediatric mTBI. METHODS: We retrospectively identified pediatric mTBI patients with pneumocephalus using the institutional database of a large regional trauma referral center. Outcome measures were defined as clinically important TBI (ciTBI), hospitalization, intensive care unit (ICU) admission, and neurosurgical intervention. Comparisons were made between pneumocephalus and control (isolated linear fracture) groups as well as between isolated (only linear fracture and pneumocephalus) and nonisolated pneumocephalus (pneumocephalus and TBI) groups. RESULTS: Among 3524 pediatric mTBI cases, 43 cases had pneumocephalus (1.2%). Twenty-one cases (48.8%) had isolated pneumocephalus. The pneumocephalus group had higher rates of ciTBI, hospital admission, ICU admission, and neurosurgery when compared with the isolated linear fracture (control) group. The isolated pneumocephalus group had fewer ciTBI (21.1% vs 70%, P = 0.002), fewer hospitalization (23.8% vs 81.8%, P < 0.001), but similar ICU admission rates (4.8% vs 22.7%, P = 0.089) and length of hospital stay (4.0 ± 2.7 vs 3.6 ± 2.4 days, P = 0.798) in comparison to the nonisolated pneumocephalus group. None of the patients in the isolated group had neurosurgery whereas 2 patients in the nonisolated pneumocephalus group underwent surgery. Multivariable analysis revealed pneumocephalus as an independent predictor of ciTBI and hospital admission, but not ICU admission or neurosurgical intervention. CONCLUSION: Pneumocephalus is associated with increased rates of hospitalization and ciTBI, but not ICU admission, unfavorable outcome, or neurosurgical intervention in pediatric mTBI. Although usually spontaneously resolving pathology, it may occasionally be linked with complications such as cerebrospinal fluid leakage, meningitis, and tension pneumocephalus. Therefore, careful evaluation, close observation, and early detection of complications may prevent adverse outcomes.

Extracellular-Vesicle-Based Cancer Panels Diagnose Glioblastomas with High Sensitivity and Specificity.

Glioblastoma is one of the most devastating neoplasms of the central nervous system. This study focused on the development of serum extracellular vesicle (EV)-based glioblastoma tumor marker panels that can be used in a clinic to diagnose glioblastomas and to monitor tumor burden, progression, and regression in response to treatment. RNA sequencing studies were performed using RNA isolated from serum EVs from both patients (n = 85) and control donors (n = 31). RNA sequencing results for preoperative glioblastoma EVs compared to control EVs revealed 569 differentially expressed genes (DEGs, 2XFC, FDR < 0.05). By using these DEGs, we developed serum-EV-based biomarker panels for the following glioblastomas: wild-type IDH1 (96% sensitivity/80% specificity), MGMT promoter methylation (91% sensitivity/73% specificity), p53 gene mutation (100% sensitivity/89% specificity), and TERT promoter mutation (89% sensitivity/100% specificity). This is the first study showing that serum-EV-based biomarker panels can be used to diagnose glioblastomas with a high sensitivity and specificity.

Middle meningeal artery embolization associated with reduced chronic subdural hematoma volume and midline shift in the acute postoperative period.

BACKGROUND: Middle meningeal artery (MMA) embolization for endovascular treatment of chronic subdural hematoma (cSDH) is growing in popularity. cSDH volume and midline shift were analyzed in the immediate postoperative window after MMA embolization. METHODS: A retrospective analysis of cSDHs managed via MMA embolization from January 1, 2018 to March 30, 2021 was performed at a large quaternary center. Pre- and postoperative cSDH volume and midline shift were quantified with CT. Postoperative CT was obtained 12 to 36 hours after embolization. Paired t-tests were used to determine significant reduction. Multivariate analysis was performed using logistic and linear regression for percent improvement from baseline volume. RESULTS: In total, 80 patients underwent MMA embolization for 98 cSDHs during the study period. The mean (SD) initial cSDH volume was 66.54 (34.67) mL, and the mean midline shift was 3.79 (2.85) mm. There were significant reductions in mean cSDH volume (12.1 mL, 95% CI 9.32 to 14.27 mL, P<0.001) and midline shift (0.80 mm, 95% CI 0.24 to 1.36 mm, P<0.001). In the immediate postoperative period, 22% (14/65) of patients had a>30% reduction in cSDH volume. A multivariate analysis of 36 patients found that preoperative antiplatelet and anticoagulation use was significantly associated with an expansion in volume (OR 0.028, 95% CI 0.000 to 0.405, P=0.03). CONCLUSION: MMA embolization is safe and effective for the management of cSDH and is associated with significant reductions in hematoma volume and midline shift in the immediate postoperative period.

Effects of Topically Applied Contractubex® on Epidural Fibrosis and Axonal Regeneration in Injured Rat Sciatic Nerve.

AIM: To investigate the effects of Contractubex® (Cx) on peripheral nerve regeneration and scar formation. MATERIAL AND METHODS: A surgical procedure involving sciatic nerve incision in 24 adult male Sprague-Dawley rats followed by epineural suturing was performed. In weeks 4 and 12 following surgery, macroscopic, histological, functional, and electromyographic examinations of the sciatic nerve were conducted. RESULTS: No significant difference was found between the Cx group and the control group in terms of sciatic function index (SFI) and distal latency results at week 4 (p > 0.05). However, significant improvements in the Cx group were observed in SFI amplitudes and nerve action potentials at week 12 (p < 0.001 and p < 0.001, respectively). Significant improvements were found in the amplitudes of nerve action potentials in the treatment group after weeks 4 and 12 (p < 0.05 and p < 0.001, respectively). Macroscopically and histopathologically, epidural fibrosis decreased (p < 0.05 and p < 0.001, respectively). For both measurement times, the treatment group had significantly higher numbers of axons (week 4, p < 0.05; week 12, p < 0.001), and the treatment group had better results regarding its axon area (weeks 4 and 12, p < 0.001) and myelin thickness (weeks 4 and 12, p < 0.05). CONCLUSION: Cx, which is applied topically in peripheral nerve injury, affects axonal regeneration and axonal maturation positively and reduces the functional loss.

A Novel Surgical Classification of the Sylvian Fissure and Its Implications on the Clinical and Radiological Outcomes of Patients Undergoing Clipping for Unruptured Middle Cerebral Artery Aneurysms.

BACKGROUND: The main access route for middle cerebral artery (MCA) aneurysms is the transsylvian approach. Although Sylvian fissure (SF) variations have been assessed, none have examined how this affects MCA aneurysm surgery. The objective of this study is to investigate how SF variants affect clinical and radiological outcomes for surgically-treated unruptured MCA aneurysms. METHODS: This retrospective study examined consecutive unruptured MCA aneurysms in 101 patients undergoing SF dissection and aneurysm clipping. SF anatomical variants were categorized using a novel functional anatomical classification: Type I: Wide straight, Type II: Wide with frontal and/or temporal opercula herniation, Type III: Narrow straight, and Type IV: Narrow with frontal and/or temporal opercula herniation. The relationships between SF variants and postoperative edema, ischemia, hemorrhage, vasospasm, and Glasgow Outcome Scale (GOS) were analyzed. RESULTS: Study included 101 patients (53.5% women), 60.9 ± 9.4 (range 24-78) years. SF types were 29.7% Type I, 19.8% Type II, 35.6% Type III, and 14.9% Type IV. The SF type with the highest proportion of females was Type IV (n = 11, 73.3%), while it was Type III for males (n = 23, 63.9%) (P = 0.03). There were significant differences between SF types, ischemia, and edema (P < 0.001, P = 0.008, respectively). Although narrow SF types had poorer GOS scores (P = 0.055), there were no significant differences between SF types and GOS, postoperative hemorrhage, vasospasm, or hospital stay. CONCLUSIONS: Sylvian fissure variants may impact intraoperative complications during aneurysm surgery. Thus, presurgical determination of SF variants can predict surgical difficulties, thereby potentially reducing morbidity for patients with MCA aneurysms and other pathologies requiring SF dissection.

Three-Dimensional Modeling and Augmented Reality and Virtual Reality Simulation of Fiber Dissection of the Cerebellum and Brainstem.

BACKGROUND: Surgeons must understand the complex anatomy of the cerebellum and brainstem and their 3-dimensional (3D) relationships with each other for surgery to be successful. To the best of our knowledge, there have been no fiber dissection studies combined with 3D models, augmented reality (AR), and virtual reality (VR) of the structure of the cerebellum and brainstem. In this study, we created freely accessible AR and VR simulations and 3D models of the cerebellum and brainstem. OBJECTIVE: To create 3D models and AR and VR simulations of cadaveric dissections of the human cerebellum and brainstem and to examine the 3D relationships of these structures. METHODS: Ten cadaveric cerebellum and brainstem specimens were prepared in accordance with the Klingler's method. The cerebellum and brainstem were dissected under the operating microscope, and 2-dimensional and 3D images were captured at every stage. With a photogrammetry tool (Qlone, EyeCue Vision Technologies, Ltd.), AR and VR simulations and 3D models were created by combining several 2-dimensional pictures. RESULTS: For the first time reported in the literature, high-resolution, easily accessible, free 3D models and AR and VR simulations of cerebellum and brainstem dissections were created. CONCLUSION: Fiber dissection of the cerebellum-brainstem complex and 3D models with AR and VR simulations are a useful addition to the goal of training neurosurgeons worldwide.