Safety and efficacy of hydroset cranioplasty as an adjunct to gasket-seal and nasoseptal flap closure of the skull base. A case-controlled study.

BACKGROUND: Cerebrospinal fluid leak after endoscopic skull base surgery remains a significant complication. Several investigators have suggested Hydroset cranioplasty to reduce leak rates. We investigated our early experience with Hydroset and compared the rate of nasal complications and CSF leak rates with case-controlled historic controls. METHODS: We queried a prospective database of patients undergoing first time endoscopic, endonasal resection of suprasellar meningiomas and craniopharyngiomas from 2015 to 2023. We compared cases closed with a gasket seal, Hydroset, and a nasoseptal flap with those closed with only a gasket seal and nasoseptal flap. Demographics, technical considerations and postoperative outcomes (SNOT-22) were compared. RESULTS: Seventy patients met inclusion criteria, twenty patients in the Hydroset group (meningioma n = 12; craniopharyngioma n = 8) and 50 control patients (meningioma n = 25; craniopharyngioma n = 25). CSF diversion was used in fewer Hydroset patients (75%, 15/20) compared with control group (94%, 47/50; p = 0.02). CSF leak was less frequent in the Hydroset than the control group (5% versus 12%, p = 0.38). One Hydroset patient required delayed nasal debridement. SNOT-22 responses demonstrated no significant difference in sinonasal complaints between groups (Hydroset average SNOT-22 score 22.45, control average SNOT-22 score 25.90; p = 0.58). CONCLUSIONS: We demonstrate that hydroxyapatite reconstruction leads to improved CSF leak control above that provided by the gasket-seal and nasoseptal flap, without significant associated morbidity as long as the cement is fully covered with vascularized tissue.

Excitatory-inhibitory mismatch shapes node recruitment in an epileptic network.

OBJECTIVE: Focal epilepsy is thought to be a network disease, in which epileptiform activity can spread noncontiguously through the brain via highly interconnected nodes, or hubs, within existing networks. Animal models confirming this hypothesis are scarce, and our understanding of how distant nodes are recruited is also lacking. Whether interictal spikes (IISs) also create and reverberate through a network is not well understood. METHODS: We injected bicuculline into the S1 barrel cortex and employed multisite local field potential and Thy-1 and parvalbumin (PV) cell mesoscopic calcium imaging during IISs to monitor excitatory and inhibitory cells in two monosynaptically connected nodes and one disynaptically connected node: ipsilateral secondary motor area (iM2), contralateral S1 (cS1), and contralateral secondary motor area (cM2). Node participation was analyzed with spike-triggered coactivity maps. Experiments were repeated with 4-aminopyridine as an epileptic agent. RESULTS: We found that each IIS reverberated throughout the network, differentially recruiting both excitatory and inhibitory cells in all connected nodes. The strongest response was found in iM2. Paradoxically, node cM2, which was connected disynaptically to the focus, was recruited more intensely than node cS1, which was connected monosynaptically. The explanation for this effect could be found in node-specific excitatory/inhibitory (E/I) balance, as cS1 demonstrated greater PV inhibitory cell activation compared with cM2, where Thy-1 excitatory cells were more heavily recruited. SIGNIFICANCE: Our data show that IISs spread noncontiguously by exploiting fiber pathways that connect nodes in a distributed network and that E/I balance plays a critical role in node recruitment. This multinodal IIS network model can be used to investigate cell-specific dynamics in the spatial propagation of epileptiform activity.

Additive risk of surgical site infection from more than one risk factor following craniotomy for tumor.

PURPOSE: This study seeks to expound upon risk factor etiologies for surgical site infection (SSI) and investigate their combinatorial effects on infection rate following craniotomy for neuro-oncologic pathology. METHODS: Patients who underwent neuro-oncologic craniotomy between 2006 and 2020 were included. Medical records were reviewed to identify the occurrence of wound infection at ≤ 3 months postoperatively. Potential risk factors for infection included tumor pathology, location, anesthesia type, indication, ventricular entry, foreign body, brachytherapy, lumbar drain, prior operation, prior cranial radiation, prior infection, bevacizumab, and medical comorbidities (hypertension, obesity, diabetes, hyperlipidemia, other cancer, cirrhosis). Logistic regression was implemented to determine risk factors for SSI. Chi-square tests were used to assess whether the number of risk factors (e.g., 0, ≥ 1, ≥2, ≥ 3, ≥4) increases the risk of SSI compared to patients with fewer risk factors. The relative increase with each additional risk factor was also evaluated. RESULTS: A total of 1209 patients were included. SSI occurred in 42 patients (3.5%) by 90 days after surgery. Significant risk factors on multivariate logistic regression were bevacizumab (OR 40.84; p < 0.001), cirrhosis (OR 14.20, p = 0.03), foreign body placement (OR 4.06; P < 0.0001), prior radiation (OR 2.20; p = 0.03), and prior operation (OR 1.92; p = 0.04). Infection rates in the combinatorial analysis were as follows: ≥1 risk factor = 5.9% (OR 2.74; p = 0.001), ≥ 2 = 6.7% (OR 2.28; p = 0.01), ≥ 3 = 19.0% (OR 6.5; p < 0.0001), ≥ 4 = 100% (OR 30.2; p < 0.0001). CONCLUSIONS: Risk factors in aggregate incrementally increase the risk of postoperative SSI after craniotomy for tumor.

Safety and efficacy of Cesium-131 brachytherapy for brain tumors.

BACKGROUND: The introduction of Cesium-131 (Cs-131) as a radiation source has led to a resurgence of brachytherapy for central nervous system (CNS) tumors. The aim of this study was to evaluate the safety and efficacy of the largest cohort of Cs-131 patients to-date. METHODS: A retrospective review of all CNS tumors treated with resection and adjuvant Cs-131 brachytherapy at New York-Presbyterian/Weill Cornell from 2010 to 2021 was performed. Overall survival (OS) and local control (LC) were assessed with Kaplan-Meier methodology. Univariable analysis was conducted to identify patient factors associated with local recurrence or radiation necrosis. RESULTS: Adjuvant Cs-131 brachytherapy following resection was performed in 119 patients with a median follow-up time of 11.8 (IQR 4.7-23.6) months and a mean of 22.3 +/-30.3 months. 1-year survival rates were 53.3% (95%CI 41.9-64.6%) for brain metastases (BrM), 45.9% (95%CI 24.8-67.0%) for gliomas, and 73.3% (95%CI 50.9-95.7%) for meningiomas. 1-year local control rates were 84.7% for BrM, 34.1% for gliomas, and 83.3% for meningiomas (p < 0.001). For BrM, local control was superior in NSCLC relative to other BrM pathologies (90.8% versus 76.5%, p = 0.039). Radiographic radiation necrosis (RN) was identified in 10 (8.4%) cases and demonstrated an association with smaller median tumor size (2.4 [IQR 1.8-2.7 cm] versus 3.1 [IQR 2.4-3.8 cm], p = 0.034). Wound complications occurred in 14 (11.8%) patients. CONCLUSIONS: Cs-131 brachytherapy demonstrated a favorable safety and efficacy profile characterized by high rates of local control for all treated pathologies. The concept of brachytherapy has seen a resurgence given the excellent results when Cs-131 is used as a source.

Seizures initiate in zones of relative hyperexcitation in a zebrafish epilepsy model.

Seizures are thought to arise from an imbalance of excitatory and inhibitory neuronal activity. While most classical studies suggest excessive excitatory neural activity plays a generative role, some recent findings challenge this view and instead argue that excessive activity in inhibitory neurons initiates seizures. We investigated this question of imbalance in a zebrafish seizure model with two-photon imaging of excitatory and inhibitory neuronal activity throughout the brain using a nuclear-localized calcium sensor. We found that seizures consistently initiated in circumscribed zones of the midbrain before propagating to other brain regions. Excitatory neurons were both more prevalent and more likely to be recruited than inhibitory neurons in initiation as compared with propagation zones. These findings support a mechanistic picture whereby seizures initiate in a region of hyperexcitation, then propagate more broadly once inhibitory restraint in the surround is overcome.

Posterior hypothalamic involvement on pre-operative MRI predicts hypothalamic obesity in craniopharyngiomas.

PURPOSE: Hypothalamic obesity (HO) is a complication associated with craniopharyngioma (CP). Attempts have been made to perioperatively predict the development of this complication, which can be severe and difficult to treat. METHODS: Patients who underwent first transsphenoidal surgical resection in a single center between February 2005 and March 2019 were screened; those who have had prior surgery or radiation, were aged below 18 years, or did not have follow up body mass index (BMI) after surgery were excluded. Primary end point was BMI within 2 years post-surgery. Hypothalamic involvement (HI) was graded based on preoperative and postoperative imaging with regards to anterior, posterior, left and right involvement. Data on baseline demographics, pre-operative and post-operative MRI, and endocrine function were collected. RESULTS: 45 patients met the inclusion and exclusion criteria. Most patients in our cohort underwent gross total resection (n = 35 patients). 13 patients were from no HI or anterior HI only group and 22 patients were classified as both anterior (ant) and posterior (post) HI group. There was no significant difference between the two groups in the gross total, subtotal or near total resection. Pre-operative BMI and post-operative BMI were significantly higher in patients who had ant and post HI on pre-operative MRI (p < 0.05 and p < 0.01, respectively). Similarly, post-operative BMI at 13-24 months was also significantly higher in the ant and post HI group on post-op MRI (p < 0.01). There was no significant difference between the two groups in terms of baseline adrenal insufficiency, thyroid insufficiency, gonadal insufficiency, IGF-1 levels, hyperprolactinemia, and diabetes insipidus. Diabetes insipidus was more common following surgery among those who had anterior and posterior involvement on pre-operative MRI (p < 0.05). CONCLUSIONS: HO appears to be predetermined by tumor involvement in the posterior hypothalamus observed on pre-operative MRI. Posterior HI on pre-operative MRI was also associated with the development of diabetes insipidus after surgery.

[68 Ga]-DOTATATE PET/MR-based evaluation of physiologic somatostatin receptor 2 expression in the adult pituitary gland as a function of age and sex in a prospective cohort.

PURPOSE: The pituitary gland has the fourth highest physiologic avidity of [68 Ga]-DOTATATE. In order to guide our understanding of [68 Ga]-DOTATATE PET in clinical contexts, accurate characterization of the normal pituitary gland is first required. This study aimed to characterize the normal pituitary gland using dedicated brain [68 Ga]-DOTATATE PET/MRI as a function of age and sex. METHODS: A total of 95 patients with a normal pituitary gland underwent brain [68 Ga]-DOTATATE PET examinations for the purpose of diagnosing CNS SSTR2 positive tumors (mean age: 58.9, 73% female). Maximum SUV of the pituitary gland was obtained in each patient. SUV of superior sagittal sinus was obtained to calculate normalized SUV score (SUVR) of the gland. The anatomic size of the gland was collected as maximum sagittal height (MSH). Correlations with age and sex were analyzed. RESULTS: The mean SUV and SUVR of the pituitary gland were 17.6 (range: 7-59.5, SD = 7.1) and 13.8 (range: 3.3-52.6, SD = 7.2), respectively. Older females had significantly higher SUV of the pituitary gland compared to younger females. When stratified by age and sex, both older and younger females had significantly higher pituitary SUV than older males. SUVR did not differ significantly by age or sex. MSH of the pituitary gland in younger females was significantly greater than in younger males at all age cutoffs. CONCLUSION: This study provides an empiric profiling of the physiological [68 Ga]-DOTATATE avidity of the pituitary gland. The findings suggest that SUV may vary by age and sex and can help guide the use of [68 Ga]-DOTATATE PET/MRI in clinical and research settings. Future studies can build on these findings to investigate further the relationship between pituitary biology and demographic factors.

Anterior occipital condyle screw placement through the endonasal corridor: proof of concept study with cadaveric analysis.

PURPOSE: Odontoidectomy for ventral compressive pathology may result in O-C1 and/or C1-2 instability. Same-stage endonasal C1-2 spinal fusion has been advocated to eliminate risks associated with separate-stage posterior approaches. While endonasal methods for C1 instrumentation and C1-2 trans-articular stabilization exist, no hypothetical construct for endonasal occipital instrumentation has been validated. We provide an anatomic description of anterior occipital condyle (AOC) screw endonasal placement as proof-of-concept for endonasal craniocervical stabilization. METHODS: Eight adult, injected cadaveric heads were studied for placing 16 AOC screws endonasally. Thin-cut CT was used for registration. After turning a standard inferior U-shaped nasopharyngeal flap endonasally, 4 mm × 22 mm AOC screws were placed with a 0° driver using neuronavigation. Post-placement CT scans were obtained to determine: site-of-entry, measured from the endonasal projection of the medial O-C1 joint; screw angulation in sagittal and axial planes, proximity to critical structures. RESULTS: Average site-of-entry was 6.88 mm lateral and 9.74 mm rostral to the medial O-C1 joint. Average angulation in the sagittal plane was 0.16° inferior to the palatal line. Average angulation in the axial plane was 23.97° lateral to midline. Average minimum screw distances from the jugular bulb and hypoglossal canal were 4.80 mm and 1.55 mm. CONCLUSION: Endonasal placement of AOC screws is feasible using a 0° driver. Our measurements provide useful parameters to guide optimal placement. Given proximity of hypoglossal canal and jugular bulb, neuronavigation is recommended. Biomechanical studies will ultimately be necessary to evaluate the strength of AOC screws with plate-screw constructs utilizing endonasal C1 lateral mass or C1-2 trans-articular screws as inferior fixation points.

Histology of high-grade glioma samples resected using 5-ALA fluorescent headlight and loupe combination.

PURPOSE: 5-Aminolevulinic acid (5-ALA) fluorescence-guided resection of high-grade gliomas (HGG) increases the extent of resection (EOR) and progression-free survival. The headlamp/loupe combination has been introduced as a method of performing fluorescent-guided surgery. This study aims to understand the correlation between fluorescent intensity and histology and between residual fluorescence and radiographic EOR utilizing the headlamp/loupe device. METHODS: Intraoperative samples resected using the headlamp/loupe device from 14 patients were labeled as PINK, VAGUE, or NEGATIVE depending on the degree of fluorescence. Histological assessment of microvascular proliferation, necrosis, and cell density was performed, and samples were classified as histologically consistent with glioblastoma (GBM), high-grade infiltrating glioma (HGIG), IG, or non-diagnostic (NDX). The presence of intraoperative residual fluorescence was compared to EOR on post-operative MRI. RESULTS: There was a significant difference in cell density comparing PINK, VAGUE, and NEGATIVE specimens (ANOVA, p < 0.00001). The PPV of PINK for GBM or HGIG was 88.4% (38/43). The NPV of NEGATIVE for IG or NDX was 74.4% (29/39). The relationship between the degree of fluorescence determination and histological results was significant (X2 (6 degrees of freedom, N = 101) = 42.57, p < 0.00001). The PPV of intraoperative GTR for post-operative GTR on MRI was 100%, while the NPV of intraoperative STR for post-operative STR on MRI was 60%. CONCLUSION: The headlamp/loupe device provides information about histology, cell density, and necrosis with similar PPV for tumor to the operative microscope. Safe complete resection of florescence has a PPV of 100% for radiographic GTR and should be the goal of surgery.

Durable headache relief following endoscopic endonasal resection of sub-centimeter Rathke cleft cysts in medically refractory patients.

BACKGROUND: The most common presenting symptom in patients with both small and large Rathke cleft cysts (RCC) is headache (H/A). It is well established that patients with large RCC can have significant symptomatic improvement after cyst drainage. However, patients with small RCC (≤ 1 cm) are rarely operated on, even if they present with debilitating H/A. It is not well understood whether resection of these smaller RCCs can lead to durable H/A resolution. METHODS: A retrospective search of our institutional database for sub-centimeter RCCs presenting with intractable H/A and treated with an endoscopic endonasal approach was carried out. A detailed H/A questionnaire as well as patient chart review was conducted to assess the long-term outcome of these patients after surgical intervention. RESULTS: Ten consecutive patients with 11 endonasal surgeries met inclusion criteria. Eight responded to the questionnaire. The median cyst diameter was 6 mm (IQR 3-9). Median preoperative H/A duration was 12 months (range 2 months-15 years). H/As occurred on average for 20 days per month and all required analgesics for symptomatic control for more than 15 of these 20 days. Half of the patients also had to miss work because of H/A. Average preoperative H/A intensity was 8.7 (scale 0-10) compared with postoperative scores of 2.9 at one month, 1.6 at 3 months, and 0.9 at 1 year. There were no permanent endocrinological or other surgical complications. After a median follow-up of 2 years, one patient had radiographic and symptomatic recurrence which resolved after re-operation. CONCLUSIONS: Endoscopic fenestration of sub-centimeter RCCs provides a safe and durable treatment for patients with intractable H/A.

Combined surgical repair and venous sinus stenting for patients with skull base encephaloceles secondary to dural venous sinus stenosis.

BACKGROUND: Chronically elevated intracranial pressure (ICP) seen in idiopathic intracranial hypertension (IIH) can cause the development of skull base encephaloceles and cerebrospinal fluid (CSF) leaks. Surgical repair and ventriculoperitoneal shunt (VPS) placement are mainstays of treatment. Venous sinus stenting (VSS) is a newly accepted treatment modality. The goal of this study was thus to determine if VSS can be used to treat symptoms and prevent recurrence after surgical encephalocele repair. METHODS: Retrospective chart review of patients that had surgical repair of encephaloceles followed by VSS for symptomatic stenosis with elevated pressure gradient. RESULTS: A total of 13 patients underwent a combined encephalocele repair and VSS. Seventy-two percent were female; 46% had headaches, 69% pulsatile tinnitus, and 92% CSF rhinorrhea or otorrhea. One had seizures. Mean lumbar opening pressure was 23.3 ± 2.6 cm H2O; the average sagittal-to-jugular pressure gradient was 12.7 ± 1.8 cmH2O and was elevated in all patients. Four patients had middle fossa craniotomy for repair of tegmen defect (one bilateral); one had a retrosigmoid craniotomy for repair of a sigmoid plate defect. Eight had an endoscopic endonasal repair for sphenoid or cribriform plate encephalocele. There were no VSS procedural complications or complications associated with dual antiplatelet therapy. One patient had meningitis after endoscopic repair that was treated with antibiotics. One patient had recurrence of both CSF leak and venous stenosis adjacent to the stent requiring repeat repair and VSS. There was no further recurrence. CONCLUSION: In patients with dural sinus stenosis and encephaloceles requiring repair, VSS can be performed safely within weeks of surgery for relief of symptoms, resolution of underlying pathology, and prevention of CSF leak recurrence.

Update on management of craniopharyngiomas.

PURPOSE/INTRODUCTION: Craniopharyngiomas are locally-aggressive tumors arising along the hypothalamic-pituitary axis. Treatment is nuanced as a result of their proximity and adherence to vital neurovascular structures and responsiveness to surgery, radiation and, in some cases, chemotherapy. METHODS: We reviewed the literature discussing the current state of knowledge regarding craniopharyngioma biology and therapy. RESULTS: Recent advances in endoscopic endonasal surgery (EEA) have made surgery a safer and more effective option. While cure may be achieved with gross total resection (GTR), when felt to be too risky, a subtotal resection followed by radiation is often a more prudent strategy, particularly in children with hypothalamic invasion. Data on long-term outcome are mostly derived from older studies in which a craniotomy, rather than EEA, was performed. Long-term EEA outcome studies are lacking. Enhanced knowledge of the biological basis of papillary CPs has led to novel medical treatments for BRAFv600E variants that appear to be effective. CONCLUSION: Endoscopic technology has improved surgical results for craniopharyngiomas and expanded the indications for the transsphenoidal approach. The goal of CP surgery goal is maximal safe resection to achieve cure, but subtotal resection and radiation may be equally effective. Early diagnosis of specific variants will facilitate enrollment in promising medical trials.

Brachytherapy for central nervous system tumors.

Radiation is a mainstay of treatment for central nervous system (CNS) tumors. Brachytherapy involves the placement of a localized/interstitial radiation source into a tumor or resection bed and has distinct advantages that can make it an attractive form of radiation when used in the appropriate setting. However, the data supporting use of brachytherapy is clouded by variability in radiation sources, techniques, delivered doses, and trial designs. The goal of this manuscript is to identify consistent themes, review the highest-level evidence and potential indications for brachytherapy in CNS tumors, as well as highlight avenues for future work. Improved understanding of the underlying biology, indications, complications, and evolving industry-academic collaborations, place brachytherapy on the brink of a resurgence.

Surgical strategies in the treatment of MR-negative Cushing's Disease: a systematic review and treatment algorithm.

PURPOSE: Several surgical strategies have been proposed to treat MRI-negative Cushing's Disease. These include tumor removal, if identified, and if a tumor is not identified, resection of varying degrees of the pituitary gland, often guided by inferior petrosal sinus sampling (IPSS). The relative risks and benefits of each strategy have never been compared. METHODS: This systematic review of the literature included only studies on the results of surgery for MRI-negative patients with Cushing's Disease in which the surgical strategy was clearly described and associated remission and/or hypopituitarism rates detailed for each strategy. RESULTS: We identified 12 studies that met inclusion criteria for remission rates and 5 studies for hypopituitarism rates. We divided cases into 6 resection strategies. Remission and hypopituitarism rates for each strategy were: (1) tumor identified, resect tumor only (68%, 0%); (2) resect tumor and surrounding capsule (85%, 0%); and if the tumor was not identified (3) resect inferior 1/3 of gland (78%, no data); (4) resect 30-50% of gland based on IPSS (68%, 13%); (5) resect > 50% but < 100% of gland (65%, 9%); (6) resect entire gland (66%, 67%). Strategy 3 only contained 9 patients. CONCLUSION: Remission rates for MRI-negative Cushing's Disease support surgery as a reasonable approach. Results are best if a tumor is found. If a tumor is not identified, one can either remove one-third of the gland guided by IPSS lateralization, or remove both lateral portions along with the inferior portion leaving sufficient central gland to preserve function. Our recommendations are limited by the lack of rigorous and objective data.

Pediatric pituitary adenomas are more aggressive, more likely to be hormone producing and are more difficult to cure than adult pituitary adenomas: case series and systematic literature review.

PURPOSE: Pediatric pituitary adenomas (pPAs) are uncommon. Thus, their presentation and outcomes after treatment are less well-understood than those of pituitary adenomas in adulthood (aPAs). METHODS: A retrospective chart review was conducted for all patients who underwent endoscopic endonasal transsphenoidal surgery (EETS) for pPA at NewYork-Presbyterian Hospital/Weill Cornell Medicine (NYP/WCM) from 2005-2020. Eleven patients were identified, and information pertaining to age, sex, adenoma characteristics, procedural details, and outcomes was reviewed. A systematic review of the literature was also performed to compare outcomes of EETS versus microscopic endonasal transsphenoidal surgery (METS) for pPA. RESULTS: From 2005-2020, 11 patients underwent EETS for pPA at NYP/WCM. Mean age at operation was 14.9 ± 2.7 years, and 5 patients (45.5%) were male. 10 adenomas (90.9%) were hormone-producing. Of the functional adenomas, 8 (80.0%) were PRL-secreting and 2 (20.0%) were GH-secreting. Maximum adenoma diameter (MAD) ranged from 1.2-5.1 cm, with a median of 1.55 cm. Cavernous sinus invasion (CSI) occurred in 2 patients with macroprolactinoma. Gross total resection (GTR) was achieved in 10 (90.9%). Biochemical remission occurred in 5/10 (50.0%). Post-operative complications were documented in 8 cases (72.7%) and included diabetes insipidus, hypopituitarism, sinusitis, weight gain, cerebrospinal fluid leak, meningitis, and hydrocephalus. Systematic literature review of 105 microscopic and 175 endoscopic cases revealed high frequency of hormone-producing tumors (83.6%) and similar rates of GTR (82.4% vs 85.1%) and biochemical cure (75.8% vs 64.3%). CONCLUSIONS: pPAs are more likely to be hormone producing and may be more aggressive and difficult to cure than aPAs. EETS is an effective treatment, although complication rates may be higher than in adult populations.

Combined use of vancomycin powder and betadine irrigation lowers the incidence of postcraniotomy wound infection in low-risk cases: a single-center risk-stratified cohort analysis.

PURPOSE: Postoperative surgical site infections (SSIs) constitute a significant source of morbidity for neurosurgical patients. Protocols that minimize postoperative wound infections are integral to improving outcomes and curtailing expenditures. The present study seeks to identify risk factors for infection and assess the efficacy of prophylactic betadine irrigation and vancomycin powder in addition to standard antibiotic irrigation. METHODS: We reviewed craniotomies performed by THS at Weill Cornell/New York Presbyterian Hospital to treat neuro-oncologic pathology. Patients were divided into three groups: group 1 - antibiotic irrigation, group 2 - antibiotic irrigation and betadine irrigation, group 3 - antibiotic irrigation, betadine irrigation, and vancomycin powder. SSI was confirmed with bacterial culture. Risk factor identification and assessment of treatment paradigms was performed using chi-square tests and univariate logistic regression. RESULTS: Among 1209 total patients, the 30- and 90-day SSI rates were 1.7% and 3.5%, respectively. Significant predictors of SSI included preoperative use of bevacizumab (OR 40.84; p < 0.0001), foreign body (OR 4.06; p < 0.0001), prior radiation (OR 2.20; p = 0.03), and prior operation/biopsy (OR 1.92; p = 0.04). Risk of infection was 2.1% in low-risk cases and 6.9% in high-risk cases. A significant, incremental decrement in SSIs was identified between the prophylaxis groups, although only among low-risk cases: group 1: 4.53%, group 2: 1.39%, group 3: 0.42% (p = 0.02). Neither vancomycin powder nor betadine significantly reduced the risk of SSI in patients with one or more risk factors. CONCLUSION: Vancomycin powder with betadine irrigation decreased SSI rates following neuro-oncologic cranial procedures in patients at low risk of infection (i.e., no preoperative risk factors).

Pituitary society expert Delphi consensus: operative workflow in endoscopic transsphenoidal pituitary adenoma resection.

PURPOSE: Surgical workflow analysis seeks to systematically break down operations into hierarchal components. It facilitates education, training, and understanding of surgical variations. There are known educational demands and variations in surgical practice in endoscopic transsphenoidal approaches to pituitary adenomas. Through an iterative consensus process, we generated a surgical workflow reflective of contemporary surgical practice. METHODS: A mixed-methods consensus process composed of a literature review and iterative Delphi surveys was carried out within the Pituitary Society. Each round of the survey was repeated until data saturation and > 90% consensus was reached. RESULTS: There was a 100% response rate and no attrition across both Delphi rounds. Eighteen international expert panel members participated. An extensive workflow of 4 phases (nasal, sphenoid, sellar and closure) and 40 steps, with associated technical errors and adverse events, were agreed upon by 100% of panel members across rounds. Both core and case-specific or surgeon-specific variations in operative steps were captured. CONCLUSIONS: Through an international expert panel consensus, a workflow for the performance of endoscopic transsphenoidal pituitary adenoma resection has been generated. This workflow captures a wide range of contemporary operative practice. The agreed "core" steps will serve as a foundation for education, training, assessment and technological development (e.g. models and simulators). The "optional" steps highlight areas of heterogeneity of practice that will benefit from further research (e.g. methods of skull base repair). Further adjustments could be made to increase applicability around the world.

Eyebrow supraorbital keyhole craniotomy for olfactory groove meningiomas with endoscope assistance: case series and systematic review of extent of resection, quantification of postoperative frontal lobe injury, anosmia, and recurrence.

BACKGROUND: Olfactory groove meningiomas (OGMs) are commonly treated with open craniotomy. Endonasal approaches have also been described. OBJECTIVE: To present clinical and radiographic outcomes for the minimally invasive eyebrow incision supraorbital keyhole approach with endoscopic assistance for OGMs. METHODS: We performed a retrospective single-center cohort study and a systematic literature review. RESULTS: Fifteen patients were identified, all with Grade I meningiomas. Radiographic gross total resection of enhancing tumor was achieved in all patients. Mean frontal lobe fluid-attenuated inversion recovery volume decreased from 11.1 ± 18.3 cm3 preoperatively to 9.9 ± 11.4 cm3 immediately postoperatively, and there was minimal new restricted diffusion (3.2 ± 2.2 cm3; max 7.5 cm3). Median length of stay was 3 days (range 2-8). Vision was improved in 4 (80%) and stable in 1 (20%) of 5 patients with a preoperative deficit. New postoperative anosmia occurred in 3 (23%) of 13 patients with any preoperative olfaction. All patients were satisfied with their cosmetic result at 3 months. After a median follow-up of 32.2 months, there were 2 (13.3%) asymptomatic radiographic recurrences, 1 treated with radiosurgery and the other with endoscopic endonasal approach (EEA). No patients required further craniotomy. Systematic review revealed the present series to be the largest to date reporting disaggregated outcomes for the eyebrow approach to OGM. CONCLUSION: The eyebrow incision supraorbital keyhole craniotomy with endoscopic assistance is a safe and effective approach to OGM with tumor control rates similar to more invasive open approaches and better than the endonasal approach. Rates of frontal lobe injury, CSF leak and anosmia are comparatively low.

Burst suppression uncovers rapid widespread alterations in network excitability caused by an acute seizure focus.

Burst suppression is an electroencephalogram pattern of globally symmetric alternating high amplitude activity and isoelectricity that can be induced by general anaesthetics. There is scattered evidence that burst suppression may become spatially non-uniform in the setting of underlying pathology. Here, we induced burst suppression with isoflurane in rodents and then created a neocortical acute seizure focus with injection of 4-aminopyridine (4-AP) in somatosensory cortex. Burst suppression events were recorded before and after creation of the focus using bihemispheric wide-field calcium imaging and multielectrode arrays. We find that the seizure focus elicits a rapid alteration in triggering, initiation, and propagation of burst suppression events. Compared with the non-seizing brain, bursts are triggered from the thalamus, initiate in regions uniquely outside the epileptic focus, elicit marked increases of multiunit activity and propagate towards the seizure focus. These findings support the rapid, widespread impact of focal epilepsy on the extended brain network.

In Vivo Femtosecond Laser Subsurface Cortical Microtransections Attenuate Acute Rat Focal Seizures.

Recent evidence shows that seizures propagate primarily through supragranular cortical layers. To selectively modify these circuits, we developed a new technique using tightly focused, femtosecond infrared laser pulses to make as small as ~100 µm-wide subsurface cortical incisions surrounding an epileptic focus. We use this "laser scalpel" to produce subsurface cortical incisions selectively to supragranular layers surrounding an epileptic focus in an acute rodent seizure model. Compared with sham animals, these microtransections completely blocked seizure initiation and propagation in 1/3 of all animals. In the remaining animals, seizure frequency was reduced by 2/3 and seizure propagation reduced by 1/3. In those seizures that still propagated, it was delayed and reduced in amplitude. When the recording electrode was inside the partially isolated cube and the seizure focus was on the outside, the results were even more striking. In spite of these microtransections, somatosensory responses to tail stimulation were maintained but with reduced amplitude. Our data show that just a single enclosing wall of laser cuts limited to supragranular layers led to a significant reduction in seizure initiation and propagation with preserved cortical function. Modification of this concept may be a useful treatment for human epilepsy.