Intraoperative Electrocorticography in Awake Brain Surgery: Comparing Three Electrode Configurations for Detecting Stimulus-induced and Spontaneous Epileptiform Activity (P7-10.006)
Objectives: Despite advantages of titanium mesh, hardware exposure affects up to 25% of cases reported in the literature. We aim to identify risk factors associated with titanium mesh exposure following cranioplasty and characterize early wound changes that may signal impending hardware exposure. Methods: A review of 34 patients who underwent titanium mesh cranioplasty between 2015 and 2025 was performed. Seventeen patients with hardware exposure were matched 1:1 with 17 controls. Data on demographics, comorbidities, operative details, and postoperative complications were collected. Statistical analysis included Fisher exact test and t tests, with significance set at P <0.05. Results: Significant risk factors for titanium hardware exposure included a history of metal allergy and reconstruction with advancement flaps. Significant protective factors included patients undergoing postoperative radiation therapy and reconstruction with rotational flaps. Conclusions: Titanium mesh exposure risk increases with metal allergy history, postoperative radiotherapy, and use of advancement flaps for reconstruction. Recognition of early wound changes is crucial for timely intervention. These findings support individualized surgical planning and highlight the need for close postoperative monitoring to reduce complications and improve reconstructive outcomes.
Subcortical Stimulation for Functional Brain Mapping: A Systematic Review
Purpose: Subcortical functional brain mapping is a valuable technique, especially involving lesions within or near white matter tracts. Motor and language deficits caused by intraoperative damage to these subcortical fibers are associated with worse outcomes. However, there are variable approaches to performing subcortical functional brain mapping. This systematic review was performed to better understand indications and optimal stimulation parameters. Methods: A systematic review was performed by PRISMA guidelines, using PubMed, Scopus, and Medline databases. Search dates ranged from inception to November 30th, 2024. Studies included adults who underwent subcortical electrical stimulation for functional brain mapping. Results: A total of 55 articles (249 patients, mean age 44.8 years, 114 female) were included. The most common pathology was brain tumor (96.3%), primarily gliomas and metastases, and 24.4% of all cases had a history of epilepsy. The most frequently mapped white matter tracts were the arcuate fasciculus, corticospinal/pyramidal tract, and inferior fronto-occipital fasciculus, involving motor, language, and cognitive functions. Bipolar stimulation (50–60 Hz, 0.5–1 millisecond, 1–10 mA) was preferred over monopolar stimulation. Among 147 patients with outcome data, 89.1% did not suffer permanent adverse outcomes including neurologic deficits, although long-term outcomes were inconsistently reported. Conclusions: The methodologic variability of subcortical functional brain mapping and lack of long-term follow-up reported limits determination of optimal parameter selection for electrical stimulation although common trends are reported. Functional brain mapping approaches may be guided by the tract and network involved. Further studies are needed to develop a standardized approach and more definitive guideline to its performance.
Intraoperative electrocorticography in awake brain surgery: comparing three electrode configurations for detecting stimulus-induced and spontaneous epileptiform activity
OBJECTIVE The aim of this study was to compare 3 electrode designs—a novel 22-contact circular grid, standard 6-contact strip, and high-density (HD) grid between 32 and 64 contacts—for the detection of epileptiform activity during awake craniotomy. METHODS This study included patients who underwent functional brain mapping with and without direct electrical stimulation during awake craniotomy. Demographic, clinical, and electrocorticography (ECoG) data were collected. RESULTS A total of 194 patients were included, with 264 instances of electrode use: 113 circular grid, 96 strip electrode, and 55 HD grid. The HD grid (15%) was used less to record ECoG during direct electrical stimulation than the circular grid (80%, p < 0.001) and strip electrodes (69%, p < 0.001). Sporadic interictal epileptiform activity was better detected with circular (45%, p < 0.001) and HD (40%, p = 0.006) grids compared with strip electrodes (16%). Spontaneous seizures were recorded more frequently with the circular grid (16%, p = 0.018) compared with the strip electrode (9.4%) and HD grid (1.8%). Afterdischarges were more frequently detected by the circular grid (69%, p = 0.031) and with circular and HD grids (combined) compared with strip electrodes (67% vs 48%, p = 0.024), at lower median intensity (3 mA vs 5 mA, p < 0.001). Multivariable analyses demonstrated circular grids (p < 0.001) to be more sensitive in detecting spontaneous epileptiform activity than strip and HD grid electrodes, and grids (circular and HD) to be better in recording stimulus-induced epileptiform activity (p = 0.01). CONCLUSIONS This study demonstrates a higher rate of detection of epileptiform activity with circular and standard grids when compared with strip electrodes. The standard HD grid was used less during electrical stimulation, demonstrating the importance of both the number of contacts and design array when considering optimal conditions for ECoG and functional brain mapping.
Association between Objective and Subjective Olfactory Dysfunction in SARS-CoV-2-Positive Patients Undergoing Skull Base Surgery
Abstract This study aimed to investigate the association between objective and subjective olfactory assessments in patients with recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection undergoing endoscopic endonasal skull base surgery (EESBS). Retrospective cohort study. Academic medical center. Adult patients with and without recent SARS-CoV-2 infection who underwent EESBS for sellar and parasellar lesion resection between 2020 and 2024 at the Mayo Clinic in Florida, Jacksonville, FL. Pre- and postoperative self-reported olfactory dysfunction and University of Pennsylvania Smell Identification Test (UPSIT) scores were collected. Patients with recent SARS-CoV-2 infection had a similar rate of discrepant preoperative objective olfactory assessments (38.2%, 26/68) compared with SARS-CoV-2-negative patients (39.9%, 127/318). SARS-CoV-2-positive patients were twice as likely to report postoperative subjective olfactory dysfunction (46.2%, 12/26) compared with SARS-CoV-2-negative patients (18.1%, 23/127, p = 0.002). There was no statistically significant difference in the mean preoperative (p = 0.162) or postoperative (p = 0.724) UPSIT scores between both groups. Patients with recent SARS-CoV-2 infection and discrepant preoperative objective olfactory assessments were twice as likely to self-report olfactory dysfunction following EESBS compared with SARS-CoV-2-negative controls. This increase in self-reported olfactory dysfunction was not accompanied by changes in objective psychophysical testing. These findings suggest that SARS-CoV-2 infection may impact subjective olfactory recovery following EESBS.
Rapid detection of IDH mutations in gliomas by intraoperative mass spectrometry
The development and performance of two mass spectrometry (MS) workflows for the intraoperative diagnosis of isocitrate dehydrogenase (IDH) mutations in glioma is implemented by independent teams at Mayo Clinic, Jacksonville, and Huashan Hospital, Shanghai. The infiltrative nature of gliomas makes rapid diagnosis necessary to guide the extent of surgical resection of central nervous system (CNS) tumors. The combination of tissue biopsy and MS analysis used here satisfies this requirement. The key feature of both described methods is the use of tandem MS to measure the oncometabolite 2-hydroxyglutarate (2HG) relative to endogenous glutamate (Glu) to characterize the presence of mutant tumor. The experiments i) provide IDH mutation status for individual patients and ii) demonstrate a strong correlation of 2HG signals with tumor infiltration. The measured ratio of 2HG to Glu correlates with IDH-mutant (IDH-mut) glioma ( P < 0.0001) in the tumor core data of both teams. Despite using different ionization methods and different mass spectrometers, comparable performance in determining IDH mutations from core tumor biopsies was achieved with sensitivities, specificities, and accuracies all at 100%. None of the 31 patients at Mayo Clinic or the 74 patients at Huashan Hospital were misclassified when analyzing tumor core biopsies. Robustness of the methodology was evaluated by postoperative re-examination of samples. Both teams noted the presence of high concentrations of 2HG at surgical margins, supporting future use of intraoperative MS to monitor for clean surgical margins. The power of MS diagnostics is shown in resolving contradictory clinical features, e.g., in distinguishing gliosis from IDH-mut glioma.
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Variants Are Associated With Disease Risk and Clinical Phenotypic Measures in Patients With Normal Pressure Hydrocephalus
Endoscopic Endonasal Resection of the Medial Wall of the Cavernous Sinus and Its Impact on Outcomes of Pituitary Surgery: A Systematic Review and Meta-Analysis
Introduction. Pituitary adenomas have the potential to infiltrate the dura mater, skull, and the venous sinuses. Tumor extension into the cavernous sinus is often observed in pituitary adenomas and techniques and results of surgery in this region are vastly discussed in the literature. Infiltration of parasellar dura and its impact for pituitary surgery outcomes is significantly less studied but recent studies have suggested a role of endoscopic resection of the medial wall of the cavernous sinus, in selected cases. In this study, we discuss the techniques and outcomes of recently proposed techniques for selective resection of the medial wall of the cavernous sinus in endoscopic pituitary surgery. Methods. We performed a systematic review of the literature using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and protocol and a total of 4 studies with 106 patients that underwent an endoscopic approach for resection of pituitary tumors with resection of medial wall from cavernous sinus were included. Clinical and radiological data were extracted (sex, mean age, Knosp, prior surgery, tumor size and type, complication rate, and remission) and a meta-analysis using the RevMan 5.4 software was performed. Results. A total of 5 studies with 208 patients were included in this analysis. The mean age of the study population was 48.87 years (range 25–82) with a female/male ratio of 1:1.36. Majority of the patients had Knosp Grade 1 (n = 77, 37.02%) and Grade 2 (n = 53, 25.48%). The complication rate was 4.81% (n = 33/106) and the most common complication observed was a new transient CN dysfunction and diplopia. Early disease remission was observed in 94.69% of the patients (n = 196/207). The prevalence rate of CS medial wall invasion varied from 10.4 % up to 36.7%. This invasion rate increased in frequency with higher Knosp Grade. The forest plot of persistent disease vs. remission in this surgery approach showed a p < 0.00001 and heterogeneity (I^2 = 0%). Discussion. Techniques to achieve resection of the medial wall of the cavernous sinus via the endoscopic endonasal approach include the “anterior to posterior” technique (opening of the anterior wall of the cavernous sinus) and the “medial to lateral” technique (opening of the inferior intercavernous sinus and). Although potentially related with improved endocrinological outcomes, these are advanced surgical techniques and require extensive anatomical knowledge and extensive surgical experience. Furthermore, to avoid procedure complications, extensive study of the patient’s configuration of cavernous ICA, Doppler-guided intraoperative imaging, surgical navigation system, and blunt tip knives to dissect the ICA’s plane are recommended. Conclusion. Endoscopic resection of the medial wall of the cavernous sinus has been associated with reports of high rates of postoperative hormonal control in functioning pituitary adenomas. However, it represents a more complex approach and requires advanced experience in endoscopic skull base surgery. Additional studies addressing case selection and studies evaluating long term results of this technique are still necessary.
Racial disparities in inpatient clinical presentation, treatment, and outcomes in brain metastasis
Abstract Background Few studies have assessed the impact of race on short-term patient outcomes in the brain metastasis population. The goal of this study is to evaluate the association of race with inpatient clinical presentation, treatment, in-hospital complications, and in-hospital mortality rates for patients with brain metastases (BM). Method Using data collected from the National Inpatient Sample between 2004 and 2014, we retrospectively identified adult patients with a primary diagnosis of BM. Outcomes included nonroutine discharge, prolonged length of stay (pLOS), in-hospital complications, and mortality. Results Minority (Black, Hispanic/other) patients were less likely to receive surgical intervention compared to White patients (odds ratio [OR] 0.70; 95% confidence interval [CI] 0.66–0.74, p < 0.001; OR 0.88; 95% CI 0.84–0.93, p < 0.001). Black patients were more likely to develop an in-hospital complication than White patients (OR 1.35, 95% CI 1.28–1.41, p < 0.001). Additionally, minority patients were more likely to experience pLOS than White patients (OR 1.48; 95% CI 1.41–1.57, p < 0.001; OR 1.34; 95% CI 1.27–1.42, p < 0.001). Black patients were more likely to experience a nonroutine discharge (OR 1.25; 95% CI 1.19–1.31, p < 0.001) and higher in-hospital mortality than White (OR 1.13; 95% CI 1.03–1.23, p = 0.008). Conclusion Our analysis demonstrated that race is associated with disparate short-term outcomes in patients with BM. More efforts are needed to address these disparities, provide equitable care, and allow for similar outcomes regardless of care.