A Novel Technique for Intraoperative Mapping of the Somatosensory Cortex.

OBJECTIVE: Intraoperative mapping of the nervous system is used to identify "eloquent" cortical areas. In this technical report, we describe a novel way of mapping the somatosensory cortex so that injury to those critical pathways can be avoided. METHODS: An 8-year-old female with drug resistant epilepsy presented for resection of a right posterior parietal focal cortical dysplasia. Left median nerve stimulation was used to record somatosensory evoked potentials (SEPs) directly from the somatosensory cortex with a strip electrode. A handheld monopolar electrode was also used to record both the median and tibial SEP. Total intravenous anesthesia with propofol and remifentanil was used. RESULTS: SEP recordings were obtained from a 4-contact strip electrode placed across the central sulcus. A phase reversal was identified and the most likely post central gyrus was noted. With the strip electrode left in place, a monopolar handheld electrode was used to record the median nerve SEPs from different locations on the postcentral gyrus. The tibial nerve was also stimulated to record where the highest amplitude tibial nerve SEP was present. This map was used delineate functionally "eloquent" areas to avoid during surgery. During resection, the median nerve SEP was recorded from the strip electrode continuously. No significant change in the SEP was noted, and the patient awoke without any sensory deficits. CONCLUSIONS: Sensory mapping of the cortex is possible with a handheld monopolar electrode. This technique is easy to perform and can help reduce neurological morbidity.

A feasibility study of several 3D printing methods for applications in epilepsy surgery.

OBJECTIVE: To describe the process of three-dimensional printing in epilepsy surgery using three different methods: low-force stereolithography (SLA), filament deposition modeling (FDM), and Polyjet Stratasys, while comparing them in terms of printing efficiency, cost, and clinical utility. MRI and CT images of patient anatomy have been limited to review in the two-dimensional plane, which provides only partial representation of intricate intracranial structures. There has been growing interest in 3D printing of physical models of this complex anatomy to be used as an educational tool and for surgical visualization. One specific application is in epilepsy surgery where there are challenges in visualizing complex intracranial anatomy in relation to implanted surgical tools. METHODS: MRI and CT data from patients with refractory epilepsy from a single center that underwent surgery are converted into 3D volumes, or stereolithography files. These were then printed using three popular 3D printing methods: SLA, FDM, and Polyjet. Faculty were surveyed on the impact of 3D modeling on the surgical planning process. RESULTS: All three methods generated physical models with an increasing degree of resolution, transparency, and clinical utility directly related to cost of production and accurate representation of anatomy. Polyjet models were the most transparent and clearly represented intricate implanted electrodes but had the highest associated cost. FDM produced relatively inexpensive models that, however, were nearly completely opaque, limiting clinical utility. SLA produced economical and highly transparent models but was limited by single material capacity. SIGNIFICANCE: Three-dimensional printing of patient-specific anatomy is feasible with a variety of printing methods. The clinical utility of lower-cost methods is limited by model transparency and lack of multi-material overlay respectively. Polyjet successfully generated transparent models with high resolution of internal structures but is cost-prohibitive. Further research needs to be done to explore cost-saving methods of modeling.

Flexible, high-resolution cortical arrays with large coverage capture microscale high-frequency oscillations in patients with epilepsy.

OBJECTIVE: Effective surgical treatment of drug-resistant epilepsy depends on accurate localization of the epileptogenic zone (EZ). High-frequency oscillations (HFOs) are potential biomarkers of the EZ. Previous research has shown that HFOs often occur within submillimeter areas of brain tissue and that the coarse spatial sampling of clinical intracranial electrode arrays may limit the accurate capture of HFO activity. In this study, we sought to characterize microscale HFO activity captured on thin, flexible microelectrocorticographic (µECoG) arrays, which provide high spatial resolution over large cortical surface areas. METHODS: We used novel liquid crystal polymer thin-film µECoG arrays (.76-1.72-mm intercontact spacing) to capture HFOs in eight intraoperative recordings from seven patients with epilepsy. We identified ripple (80-250 Hz) and fast ripple (250-600 Hz) HFOs using a common energy thresholding detection algorithm along with two stages of artifact rejection. We visualized microscale subregions of HFO activity using spatial maps of HFO rate, signal-to-noise ratio, and mean peak frequency. We quantified the spatial extent of HFO events by measuring covariance between detected HFOs and surrounding activity. We also compared HFO detection rates on microcontacts to simulated macrocontacts by spatially averaging data. RESULTS: We found visually delineable subregions of elevated HFO activity within each µECoG recording. Forty-seven percent of HFOs occurred on single 200-µm-diameter recording contacts, with minimal high-frequency activity on surrounding contacts. Other HFO events occurred across multiple contacts simultaneously, with covarying activity most often limited to a .95-mm radius. Through spatial averaging, we estimated that macrocontacts with 2-3-mm diameter would only capture 44% of the HFOs detected in our µECoG recordings. SIGNIFICANCE: These results demonstrate that thin-film microcontact surface arrays with both highresolution and large coverage accurately capture microscale HFO activity and may improve the utility of HFOs to localize the EZ for treatment of drug-resistant epilepsy.

Predictors of Blood Transfusion for Endoscopic Assisted Craniosynostosis Surgery.

ABSTRACT: Blood loss is a main cause of morbidity after craniofacial procedures. The purpose of this study is to identify the incidence and predictors for transfusion of blood products in the endoscopic assisted strip craniectomy population. Data was prospectively collected from a single-center multi-surgeon cohort of 78 consecutive patients who underwent endoscopic assisted strip craniectomy for craniosynostosis between July 2013 and December 2020. The authors reviewed patient and treatment characteristics and outcomes. Of the 78 patients, 26 patients were transfused yielding an overall rate of transfusion of 33%. The most common fused suture was sagittal (n = 42, 54%) followed by metopic (n = 15, 19%), multiple (n = 10, 13%), coronal (n = 7, 9%) and finally lambdoid (n = 4, 5%). On univariate analysis, patients' weight in the transfusion cohort were significantly lower than those who did not receive a transfusion (5.6 ± 1.1 versus 6.5 ± 1.1 kg, P = 0.0008). The transfusion group also had significantly lower preoperative hemoglobin compared to the non-transfusion group (10.6 versus 11.1, P = .049). Eleven percent patients admitted to step-down received a transfusion, whereas 39% of patients admitted to the pediatric intensive care unit received a transfusion ( P = 0.042). On multivariate analysis, only higher patient weight (operating room [OR] 0.305 [0.134, 0.693], P = 0.005) was protective against a transfusion, whereas colloid volume (OR 1.018 [1.003, 1.033], P = 0.019) predicted the need for a transfusion.Our results demonstrate that endoscopic craniosynostosis cases carry a moderate risk of transfusion. individuals with lower weight and those that receive colloid volume are also at elevated risk.

Antibacterial prophylaxis for gram-positive and gram-negative infections in cranial surgery: A meta-analysis.

BACKGROUND: Perioperative antibiotic prophylaxis against gram positive and gram negative infections is considered standard of care in the perioperative management of patients undergoing cranial surgery. The antibiotic regimen which best reduces the risk of surgical site infections (SSIs) remains controversial. OBJECTIVES: A systematic literature review and meta-analysis were conducted to examine the effect of various prophylactic antibiotics on infection incidence among patients undergoing cranial surgeries. METHODS: A comprehensive search was conducted on Pubmed, EMBASE and Cochrane databases through October 2014 for studies that evaluated the efficacy of antibiotic prophylaxis among patients undergoing cranial surgeries. Pooled effect estimates using both fixed- and random-effect models were calculated. RESULTS: Eight articles were included in the meta-analysis, with a combined total of 1655 cranial procedures. Among these, 74 cases of SSIs were reported after patients received a single antibiotic or a combination of 2 or more antibiotics (pooled incidence of SSIs=6.00%; 95% CI=4.80%, 7.50%; fixed-effects model; I2=73.7%; P-heterogeneity<0.01). Incidence of SSI was 1.00% (95% CI=0.40%, 2.60%) for non-MRSA gram-positive bacterial infections; 2.70% (95% CI=0.90%, 8.00%) for gram-negative bacterial infections; 6.00% (95% CI=4.50%, 7.80%) for gram negative, and non-MRSA gram-positive bacterial infections; and 11.3% (95% CI=7.20%, 17.4%) for gram negative and MRSA gram-positive bacterial infections. Subgroup analysis revealed an effect modification by drug class (P=0.05) and infection type (P-interaction=0.01). More specifically, lincosamides (2.70%; n=1 group), glycopeptides (2.80%; n=1), third generation cephalosporins (5.30%; n=2), antibiotics combination (4.90%; n=4), and penicillin-family antibiotics (5.90%, n=1) offered better coverage against infections than first generation cephalosporins (22.0%; n=2). A meta-regression analysis on study length was not significant (P=0.13). Random-effect models were not materially different form fixed-effects. No evidence of publication bias was found. CONCLUSION: Lincosamides, glycopeptides, third generation cephalosporins, other combinations of prophylactic antibiotics, or penicillin-family antibiotics alone offer better coverage against SSIs than first generation cephalosporin among cranial surgery patients.

The Efficacy of Antibacterial Prophylaxis Against the Development of Meningitis After Craniotomy: A Meta-Analysis.

OBJECTIVE: Prophylactic antibiotics are widely used before craniotomy to prevent postoperative infections. A systematic review and meta-analysis was conducted to examine the effect of prophylactic antibiotics on meningitis after craniotomy. METHODS: PubMed, EMBASE, and Cochrane databases were searched through October 2014 for randomized controlled trials that evaluated the effect of prophylactic antibiotics on meningitis after craniotomy. Pooled effect estimates were calculated using fixed-effects and random-effects models. RESULTS: Seven studies with 2365 patients were included in the final analysis. All studies were randomized controlled trials with different antibiotic regimens. Prophylactic antibiotic use reduced the rate of meningitis after neurosurgery, with a pooled Peto odds ratio of 0.34 (95% confidence interval 0.18-0.63). Cochran's Q test indicated no significant heterogeneity among studies (I(2) = 0; P value for heterogeneity = 0.44). Subgroup analysis based on Gram-negative coverage, blinding design, and study quality demonstrated no statistically significant difference among these groups (P> 0.05 for all). A meta-regression on surgery duration (P = 0.52) and on antibiotics duration (P = 0.59) did not show significant differences in the results among studies. CONCLUSIONS: This meta-analysis shows that prophylactic antibiotic use significantly decreases meningitis infections after craniotomy.

Effect of Hospital Safety-Net Burden on Cost and Outcomes After Surgery.

IMPORTANCE: Safety-net hospitals provide broad services for a vulnerable population of patients and are financially at risk owing to impending reimbursement penalties and policy changes. OBJECTIVE: To determine the effect of patient and hospital factors on surgical outcomes and cost at safety-net hospitals. DESIGN, SETTING, AND PARTICIPANTS: Hospitals in the University HealthSystem Consortium database from January 1, 2009, through December 31, 2012 (n = 31), were grouped according to their safety-net burden, defined as the proportion of Medicaid and uninsured patient charges for all hospitalizations during that time (n = 12,638,166). Nine cohorts, based on a variety of surgical procedures, were created and examined with regard to preoperative characteristics, postoperative outcomes, and resource utilization. Multiple logistic regression was performed to analyze the effect of patient and center factors on outcomes. Hospital Compare data from the Centers for Medicare & Medicaid Services were linked and used to characterize and compare the groups of hospitals. MAIN OUTCOMES AND MEASURES: Postoperative mortality, 30-day readmissions, and total direct cost. RESULTS: For all 9 procedures examined in 231 hospitals comprising 12,638,166 patient encounters, patients at hospitals with high safety-net burden (HBHs) (vs hospitals with low and medium safety-net burdens) were most likely to be young, to be black, to be of the lowest socioeconomic status, and to have the highest severity of illness and the highest cost for surgical care (P < .01 for all). For 7 of 9 procedures, HBHs had the highest proportion of emergent cases and longest length of stay (P < .01 for all). After adjusting for patient characteristics and center volume, HBHs still had higher odds of mortality for 3 procedures (odds ratios [ORs], 1.81-2.08; P < .05), readmission for 2 procedures (ORs, 1.19-1.30; P < .05), and the highest cost of care associated with 7 of 9 procedures (risk ratios, 1.23-1.35; P < .05). Analysis of Hospital Compare data found that HBHs had inferior performance on Surgical Care Improvement Project measures, higher rates of surgical complications, and inferior markers of emergency department timeliness and efficiency (all P < .05). CONCLUSIONS AND RELEVANCE: These data suggest that intrinsic qualities of safety-net hospitals lead to inferior surgical outcomes and increased cost across 9 elective surgical procedures. These outcomes are likely owing to hospital resources and not necessarily patient factors. In addition, impending changes to reimbursement may have a negative effect on the surgical care at these centers.

MALDI mass spectrometry imaging analysis of pituitary adenomas for near-real-time tumor delineation.

We present a proof of concept study designed to support the clinical development of mass spectrometry imaging (MSI) for the detection of pituitary tumors during surgery. We analyzed by matrix-assisted laser desorption/ionization (MALDI) MSI six nonpathological (NP) human pituitary glands and 45 hormone secreting and nonsecreting (NS) human pituitary adenomas. We show that the distribution of pituitary hormones such as prolactin (PRL), growth hormone (GH), adrenocorticotropic hormone (ACTH), and thyroid stimulating hormone (TSH) in both normal and tumor tissues can be assessed by using this approach. The presence of most of the pituitary hormones was confirmed by using MS/MS and pseudo-MS/MS methods, and subtyping of pituitary adenomas was performed by using principal component analysis (PCA) and support vector machine (SVM). Our proof of concept study demonstrates that MALDI MSI could be used to directly detect excessive hormonal production from functional pituitary adenomas and generally classify pituitary adenomas by using statistical and machine learning analyses. The tissue characterization can be completed in fewer than 30 min and could therefore be applied for the near-real-time detection and delineation of pituitary tumors for intraoperative surgical decision-making.

Intraoperative mass spectrometry mapping of an onco-metabolite to guide brain tumor surgery.

For many intraoperative decisions surgeons depend on frozen section pathology, a technique developed over 150 y ago. Technical innovations that permit rapid molecular characterization of tissue samples at the time of surgery are needed. Here, using desorption electrospray ionization (DESI) MS, we rapidly detect the tumor metabolite 2-hydroxyglutarate (2-HG) from tissue sections of surgically resected gliomas, under ambient conditions and without complex or time-consuming preparation. With DESI MS, we identify isocitrate dehydrogenase 1-mutant tumors with both high sensitivity and specificity within minutes, immediately providing critical diagnostic, prognostic, and predictive information. Imaging tissue sections with DESI MS shows that the 2-HG signal overlaps with areas of tumor and that 2-HG levels correlate with tumor content, thereby indicating tumor margins. Mapping the 2-HG signal onto 3D MRI reconstructions of tumors allows the integration of molecular and radiologic information for enhanced clinical decision making. We also validate the methodology and its deployment in the operating room: We have installed a mass spectrometer in our Advanced Multimodality Image Guided Operating (AMIGO) suite and demonstrate the molecular analysis of surgical tissue during brain surgery. This work indicates that metabolite-imaging MS could transform many aspects of surgical care.

Cerebral melioidosis for the first time in the western hemisphere.

This report is the first published case of cerebral melioidosis in the western hemisphere. In this paper the authors review the literature on neurological melioidosis and its presentation and treatment in endemic areas, describe the clinical course of this unique case of a presentation of the disease with cranial abscess in the US, review the pathological and radiological findings associated with this seminal case, and put forth recommendations for recognizing and treating possible future instances of the disease within the western hemisphere.

Symptoms of anxiety and depression in childhood absence epilepsy.

Childhood absence epilepsy (CAE) has been recently linked to a number of cognitive, behavioral, and emotional disorders. Identification of affective disorders (anxiety and depression) presents unique challenges in pediatric populations, and successful early intervention may significantly improve long-term developmental outcomes. The current study examined the specific anxiety and depression symptoms children with CAE experience, and explored the role of disease factors in the severity of their presentation. Forty-five subjects with CAE and 41 healthy matched controls, ages 6-16 years, participated in the study. The Behavior Assessment System for Children (BASC) was completed by parents, and the Anxiety and Depression subscales were used to characterize problems. Item analysis within the subscales revealed that children with CAE demonstrated higher rates of symptoms of anxiety (nervousness and thought rumination) and depression (sadness and crying), as well as more general psychosocial problems including isolation and low self-esteem. Disease duration, intractability, and medication effects were not associated with higher rates of affective problems in this limited patient sample. Screening of patients with CAE for comorbid psychiatric disorders early by focusing on specific symptom profiles unique to this population may enhance overall treatment and developmental outcomes.

Impaired attention and network connectivity in childhood absence epilepsy.

Patients with childhood absence epilepsy (CAE) often demonstrate impaired interictal attention, even with control of their seizures. No previous study has investigated the brain networks involved in this impairment. We used the continuous performance task (CPT) of attentional vigilance and the repetitive tapping task (RTT), a control motor task, to examine interictal attention in 26 children with CAE and 22 matched healthy controls. Each subject underwent simultaneous 3T functional magnetic resonance imaging-electroencephalography (fMRI-EEG) and CPT/RTT testing. Areas of activation on fMRI during the CPT task were correlated with behavioral performance and used as seed regions for resting functional connectivity analysis. All behavioral measures reflecting inattention were significantly higher in patients. Correlation analysis revealed that impairment on all measures of inattention on the CPT task was associated with decreased medial frontal cortex (MFC) activation during CPT. In addition, analysis of resting functional connectivity revealed an overall decrease within an 'attention network' in patients relative to controls. Patients demonstrated significantly impaired connectivity between the right anterior insula/frontal operculum (In/FO) and MFC relative to controls. Our results suggest that there is impaired function in an attention network comprising anterior In/FO and MFC in patients with CAE. These findings provide an anatomical and functional basis for impaired interictal attention in CAE, which may allow the development of improved treatments targeted at these networks.

Differentiation of attention-related problems in childhood absence epilepsy.

The current study examined the specific types of attention-related problems children with childhood absence epilepsy (CAE) experience and the role of disease factors in the development of attention-related problems. Thirty-eight subjects with CAE and 46 healthy controls, aged 6 to 16, participated in the study. The Behavior Assessment System for Children (BASC) was completed by parents, and the Attention Problems and Hyperactivity subscales were used to characterize the problems of children with CAE. Item analysis within the subscales revealed that children with CAE demonstrate higher rates of hyperactive (overactivity and fidgetiness) and inattentive (forgetfulness and distractibility) problems, and require more supervision. Within-CAE-group analyses revealed that those who were actively having seizures were more impatient and those with a longer duration of illness were less proficient in completing homework. Children with CAE are at risk for certain inattentive and hyperactive problems, which can differ depending on duration of illness and active seizure status.

Simultaneous EEG, fMRI, and behavior in typical childhood absence seizures.

PURPOSE: Absence seizures cause transient impairment of consciousness. Typical absence seizures occur in children, and are accompanied by 3-4-Hz spike-wave discharges (SWDs) on electroencephalography (EEG). Prior EEG-functional magnetic resonance imaging (fMRI) studies of SWDs have shown a network of cortical and subcortical changes during these electrical events. However, fMRI during typical childhood absence seizures with confirmed impaired consciousness has not been previously investigated. METHODS: We performed EEG-fMRI with simultaneous behavioral testing in 37 children with typical childhood absence epilepsy (CAE). Attentional vigilance was evaluated by a continuous performance task (CPT), and simpler motor performance was evaluated by a repetitive tapping task (RTT). RESULTS: SWD episodes were obtained during fMRI scanning from 9 patients among the 37 studied. fMRI signal increases during SWDs were observed in the thalamus, frontal cortex, primary visual, auditory, somatosensory, and motor cortex, and fMRI decreases were seen in the lateral and medial parietal cortex, cingulate gyrus, and basal ganglia. Omission error rate (missed targets) with SWDs during fMRI was 81% on CPT and 39% on RTT. For those seizure epochs during which CPT performance was impaired, fMRI changes were seen in cortical and subcortical structures typically involved in SWDs, whereas minimal changes were observed for the few epochs during which performance was spared. DISCUSSION: These findings suggest that typical absence seizures involve a network of cortical-subcortical areas necessary for normal attention and primary information processing. Identification of this network may improve understanding of cognitive impairments in CAE, and may help guide development of new therapies for this disorder.

Dynamic time course of typical childhood absence seizures: EEG, behavior, and functional magnetic resonance imaging.

Absence seizures are 5-10 s episodes of impaired consciousness accompanied by 3-4 Hz generalized spike-and-wave discharge on electroencephalography (EEG). The time course of functional magnetic resonance imaging (fMRI) changes in absence seizures in relation to EEG and behavior is not known. We acquired simultaneous EEG-fMRI in 88 typical childhood absence seizures from nine pediatric patients. We investigated behavior concurrently using a continuous performance task or simpler repetitive tapping task. EEG time-frequency analysis revealed abrupt onset and end of 3-4 Hz spike-wave discharges with a mean duration of 6.6 s. Behavioral analysis also showed rapid onset and end of deficits associated with electrographic seizure start and end. In contrast, we observed small early fMRI increases in the orbital/medial frontal and medial/lateral parietal cortex >5 s before seizure onset, followed by profound fMRI decreases continuing >20 s after seizure end. This time course differed markedly from the hemodynamic response function (HRF) model used in conventional fMRI analysis, consisting of large increases beginning after electrical event onset, followed by small fMRI decreases. Other regions, such as the lateral frontal cortex, showed more balanced fMRI increases followed by approximately equal decreases. The thalamus showed delayed increases after seizure onset followed by small decreases, most closely resembling the HRF model. These findings reveal a complex and long-lasting sequence of fMRI changes in absence seizures, which are not detectable by conventional HRF modeling in many regions. These results may be important mechanistically for seizure initiation and termination and may also contribute to changes in EEG and behavior.

Early treatment suppresses the development of spike-wave epilepsy in a rat model.

PURPOSE: Current treatments for epilepsy may control seizures, but have no known effects on the underlying disease. We sought to determine whether early treatment in a model of genetic epilepsy would reduce the severity of the epilepsy phenotype in adulthood. METHODS: We used Wistar albino Glaxo rats of Rijswijk (WAG/Rij) rats, an established model of human absence epilepsy. Oral ethosuximide was given from age p21 to 5 months, covering the usual period in which seizures develop in this model (age approximately 3 months). Two experiments were performed: (1) cortical expression of ion channels Nav1.1, Nav1.6, and HCN1 (previously shown to be dysregulated in WAG/Rij) measured by immunocytochemistry in adult treated rats; and (2) electroencephalogram (EEG) recordings to measure seizure severity at serial time points after stopping the treatment. RESULTS: Early treatment with ethosuximide blocked changes in the expression of ion channels Nav1.1, Nav1.6, and HCN1 normally associated with epilepsy in this model. In addition, the treatment led to a persistent suppression of seizures, even after therapy was discontinued. Thus, animals treated with ethosuximide from age p21 to 5 months still had a marked suppression of seizures at age 8 months. DISCUSSION: These findings suggest that early treatment during development may provide a new strategy for preventing epilepsy in susceptible individuals. If confirmed with other drugs and epilepsy paradigms, the availability of a model in which epileptogenesis can be controlled has important implications both for future basic studies, and human therapeutic trials.