ICU Cockpit: a platform for collecting multimodal waveform data, AI-based computational disease modeling and real-time decision support in the intensive care unit.

ICU Cockpit: a secure, fast, and scalable platform for collecting multimodal waveform data, online and historical data visualization, and online validation of algorithms in the intensive care unit. We present a network of software services that continuously stream waveforms from ICU beds to databases and a web-based user interface. Machine learning algorithms process the data streams and send outputs to the user interface. The architecture and capabilities of the platform are described. Since 2016, the platform has processed over 89 billion data points (N = 979 patients) from 200 signals (0.5-500 Hz) and laboratory analyses (once a day). We present an infrastructure-based framework for deploying and validating algorithms for critical care. The ICU Cockpit is a Big Data platform for critical care medicine, especially for multimodal waveform data. Uniquely, it allows algorithms to seamlessly integrate into the live data stream to produce clinical decision support and predictions in clinical practice.

Functional relationship of arterial blood pressure, central venous pressure and intracranial pressure in the early phase after subarachnoid hemorrhage.

BACKGROUND: Intracranial pressure (ICP) and arterial blood pressure (ABP) are related to each other through cerebral autoregulation. Central venous pressure (CVP) is often measured to estimate cardiac filling pressures as an approximate measure for the volume status of a patient. Prior modelling efforts have formalized the functional relationship between CVP, ICP and ABP. However, these models were used to explain short segments of data during controlled experiments and have not yet been used to explain the slowly evolving ICP increase that occurs typically in patients after aneurysmal subarachnoid hemorrhage (SAH). OBJECTIVE: To analyze the functional relationship between ICP, ABP and CVP recorded from SAH patients in the first five days after aneurysm. METHODS: Two methods were used to elucidate this relationship on the running average of the signals: First, using Spearman correlation coefficients calculated over 30 min segments Second, for each patient, linear state space models of ICP as the output and ABP and CVP as inputs were estimated. RESULTS: The mean and variance of the data and the correlation coefficients between ICP-ABP and ICP-CVP vary over time as the patient progresses through their stay in the ICU. On average, after an SAH event, the models show that a) ABP is the bigger driver of changes in ICP than CVP and that increasing ABP leads to reduction in ICP and (b) increasing CVP leads to an increase in ICP. CONCLUSIONS: Finding a) agrees with the hypothesis that patients with subarachnoid hemorrhage have defective autoregulation, and b) agrees with the positive correlation observed between central venous pressure and intracranial pressure in the literature.

The effect of nimodipine on pulmonary function in artificially ventilated patients with aneurysmal subarachnoid hemorrhage.

BACKGROUND: Nimodipine is routinely administered in patients with aneurysmal subarachnoid hemorrhage (aSAH). However, the effect of nimodipine on oxygen exchange in the lungs is insufficiently explored. METHODS: The study explored nimodipine medication in artificially ventilated patients with aSAH. The data collection period was divided into nimodipine-dependent (ND) and nimodipine-independent (NID) periods. Values for arterial partial pressure of oxygen (PaO2) and fraction of inspired oxygen (FiO2) were collected and compared between the periods. Patients were divided in those with lung injury (LI), defined as median Horowitz index (PaO2/FiO2) ≤40 kPa (≤300 mmHg), and without and in those with lower respiratory tract infection (LRTI) and without. RESULTS: A total of 53 out of 150 patients were artificially ventilated, and in 29 patients, the Horowitz index could be compared between ND and NID periods. A linear mixed model showed that during ND period the Horowitz index was 2.3 kPa (95% CI, 1.0-3.5 kPa, P<0.001) lower when compared to NID period. The model suggested that in the presence of LI, ND period is associated with a decrease of the index by 2.8 kPa (95% CI, 1.2-4.3 kPa, P<0.001). The decrease was more pronounced with LRTI than without: 3.4 kPa (95% CI, 0.8-6.1 kPa) vs. 2.1 kPa (95% CI, 0.7-3.4 kPa), P=0.011 and P=0.002, respectively. CONCLUSIONS: In patients with LI or LRTI in the context of aSAH, pulmonary function may worsen with nimodipine treatment. The drop of 2 to 3 kPa of the Horowitz index in patients with no lung pathology may not outweigh the benefits of nimodipine. However, in individuals with concomitant lung injury, the effect may be clinically relevant.

Validation and Optimization of Barrow Neurological Institute Score in Prediction of Adverse Events and Functional Outcome After Subarachnoid Hemorrhage-Creation of the HATCH (Hemorrhage, Age, Treatment, Clinical State, Hydrocephalus) Score.

BACKGROUND: The Barrow Neurological Institute (BNI) score, measuring maximal thickness of aneurysmal subarachnoid hemorrhage (aSAH), has previously shown to predict symptomatic cerebral vasospasms (CVSs), delayed cerebral ischemia (DCI), and functional outcome. OBJECTIVE: To validate the BNI score for prediction of above-mentioned variables and cerebral infarct and evaluate its improvement by integrating further variables which are available within the first 24 h after hemorrhage. METHODS: We included patients from a single center. The BNI score for prediction of CVS, DCI, infarct, and functional outcome was validated in our cohort using measurements of calibration and discrimination (area under the curve [AUC]). We improved it by adding additional variables, creating a novel risk score (measure by the dichotomized Glasgow Outcome Scale) and validated it in a small independent cohort. RESULTS: Of 646 patients, 41.5% developed symptomatic CVS, 22.9% DCI, 23.5% cerebral infarct, and 29% had an unfavorable outcome. The BNI score was associated with all outcome measurements. We improved functional outcome prediction accuracy by including age, BNI score, World Federation of Neurologic Surgeons, rebleeding, clipping, and hydrocephalus (AUC 0.84, 95% CI 0.8-0.87). Based on this model we created a risk score (HATCH-Hemorrhage, Age, Treatment, Clinical State, Hydrocephalus), ranging 0 to 13 points. We validated it in a small independent cohort. The validated score demonstrated very good discriminative ability (AUC 0.84 [95% CI 0.72-0.96]). CONCLUSION: We developed the HATCH score, which is a moderate predictor of DCI, but excellent predictor of functional outcome at 1 yr after aSAH.

Changes in the cerebrospinal fluid lipid profile following subarachnoid hemorrhage in a closed cranium model: Correlations to cerebral vasospasm, neuronal cell death and Interleukin-6 synthesis. A pilot study.

BACKGROUND: Phospholipids and sphingolipids are cell membrane components, that participate in signaling events and regulate a wide variety of vital cellular processes. Sphingolipids are involved in ischemic stroke pathophysiology. Throughout cleavage of membrane sphingomyelin by sphingomyelinase in stroke patients, it results in increased Ceramide (Cer) levels in brain tissue. Different studies showed the evidence that sphingomyelinase with Cer production induces expression of interleukin (IL)-6 and have vasoconstrictive proprieties. With this study, we intend to evaluate cerebrospinal fluid (CSF) lipid profile changes in a rabbit closed cranium subarachnoid hemorrhage (SAH) model. METHODS: A total of 14 New Zealand white rabbits were randomly allocated either to SAH or sham group. In the first group SAH was induced by extracranial-intracranial shunting from the subclavian artery into the cisterna magna. Intracranial pressure (ICP) and arterial blood pressure were continuously monitored. Digital subtraction angiography of the basilar artery, CSF and blood samples were performed at day 0 pre SAH and on day 3 post SAH. The amount of IL-6 and various lipids in CSF were quantified using ELISA and Liquid Chromatography-Mass Spectrometry respectively. Cell death was detected in bilateral basal cortex, hippocampus (CA1 and CA3) using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). RESULTS: SAH Induction led to acute increase of ICP and increased delayed cerebral vasospasm (DCVS). At follow up CSF IL-6 levels showed a significant increase compared to baseline. Between baseline and follow up there were no significant differences in any of the measured CSF Lipids irrespective of subgroups. No relevant correlation was found between IL-6 and any of the sphingolipids. We found a correlation between baseline and follow up for the phospholipids phosphatidylethanolamine and phosphatidylcholine. CONCLUSIONS: Neuronal apoptosis, DCVS and IL-6 seems not to be related to changes in CSF lipid profiles except for PEA and PC in a rabbit closed cranium SAH model.

Systematic Review and Meta-analysis of Methodological Quality in In Vivo Animal Studies of Subarachnoid Hemorrhage.

As a result of increased awareness of wide-spread methodological bias and obvious translational roadblocks in subarachnoid hemorrhage (SAH) research, various checklists and guidelines were developed over the past decades. This systematic review assesses the overall methodological quality of preclinical SAH research. An electronic search for preclinical studies on SAH revealed 3415 potential articles. Of these, 765 original research papers conducted in vivo in mice, rats, rabbits, cats, dogs, pigs, goats, and non-human primates with a focus on brain damage related to delayed cerebral vasospasm and early brain injury met the inclusion criteria. We found methodological shortcomings still to prevail in preclinical SAH research. In addition, basic animal characteristics were typically well described but important technical parameters of SAH induction were often underreported. None of the species, models, or techniques used in preclinical SAH research was methodologically superior to the others. Methodological quality of preclinical SAH research was independent of the number of citations or impact factor of a publication. Consequently, we suggest the SAH research community should consider strategies to improve preclinical research quality in their field, such as public platforms to (pre)register preclinical experiments, consequent support of open science policies, stricter editorial (and reviewer) control of (pre)existing guidelines, and increased efforts in education and training of good laboratory practice for the next generation of researchers.

Sevoflurane sedation attenuates early cerebral oedema formation through stabilisation of the adherens junction protein beta catenin in a model of subarachnoid haemorrhage: A randomised animal study.

BACKGROUND: Severe neurological impairment is a problem after subarachnoid haemorrhage (SAH). Although volatile anaesthetics, such as sevoflurane, have demonstrated protective properties in many organs, their use in cerebral injury is controversial. Cerebral vasodilation may lead to increased intracranial pressure (ICP), but at the same time volatile anaesthetics are known to stabilise the SAH-injured endothelial barrier. OBJECTIVE: To test the effect of sevoflurane on ICP and blood-brain barrier function. DESIGN: Randomised study. PARTICIPANTS: One hundred male Wistar rats included, 96 analysed. INTERVENTIONS: SAH was induced by the endoluminal filament method under ketamine/xylazine anaesthesia. Fifteen minutes after sham surgery or induction of SAH, adult male Wistar rats were randomised to 4 h sedation with either propofol or sevoflurane. MAIN OUTCOME MEASURES: Mean arterial pressure (MAP), ICP, extravasation of water (small), Evan's blue (intermediate) and IgG (large molecule) were measured. Zonula occludens-1 (ZO-1) and beta-catenin (ß-catenin), as important representatives of tight and adherens junction proteins, were determined by western blot. RESULTS: Propofol and sevoflurane sedation did not affect MAP or ICP in SAH animals. Extravasation of small molecules was higher in SAH-propofol compared with SAH-sevoflurane animals (79.1 ±â€Š0.9 vs. 78.0 ±â€Š0.7%, P = 0.04). For intermediate and large molecules, no difference was detected (P = 0.6 and P = 0.2). Both membrane and cytosolic fractions of ZO-1 as well as membrane ß-catenin remained unaffected by the injury and type of sedation. Decreased cytosolic fraction of ß-catenin in propofol-SAH animals (59 ±â€Š15%) was found to reach values of sham animals (100%) in the presence of sevoflurane in SAH animals (89 ±â€Š21%; P = 0.04). CONCLUSION: This experiment demonstrates that low-dose short-term sevoflurane sedation after SAH in vivo did not affect ICP and MAP and at the same time may attenuate early brain oedema formation, potentially by preserving adherens junctions. TRIAL REGISTRATION: No 115/2014 Veterinäramt Zürich.

[Everyone Has Low Back Pain: Degenerative Lumbar Spinal Disorders and Their Treatment Options]. / Jeder hat doch Rückenschmerzen: degenerative lumbale Wirbelsäulenerkrankungen und ihre Behandlungsmöglichkeiten.

Everyone Has Low Back Pain: Degenerative Lumbar Spinal Disorders and Their Treatment Options Abstract. Back pain is one of the most widespread diseases. Up to 84 % of people have low back pain at some point in their lives. Unspecific back pain is treated conservatively. As supportive measure, interventional pain therapy can be performed. Surgery for low back pain should be considered in selected cases only. However, accompanying neurological symptoms are frequent, such as radiation, i.e. sciatica. Typical etiologies are disc herniation or - increasingly frequent, and due to the aging population increasingly frequent - spinal canal stenosis. Surgery has a better prognosis in cases where conservative management failed. If severe neurological symptoms are present, surgery is indicated. Osteoporotic compression fractures cause acute back pain. The decision whether these patients should undergo kypho- or vertebroplasty should be based on guidelines.

Outcome, Return to Work and Health-Related Costs After Aneurysmal Subarachnoid Hemorrhage.

OBJECT: Data on health-related costs after aneurysmal subarachnoid hemorrhage (aSAH) are limited. The aim was to evaluate outcome, return to work and costs after aSAH with focus on differences between high- and low-grade aSAH (defined as World Federation of Neurological Surgeons [WFNS] grades 4-5 and WFNS 1-3, respectively). METHODS: A cross-sectional study was performed, including all consecutive survivors of aSAH over a 4-year period. A telephone interview was conducted to assess the Glasgow Outcome Scale Extended and employment status before and after aSAH. Direct costs were calculated by multiplying the length of hospitalization by the average daily costs. Indirect costs were calculated for productivity losses until retirement age according to the human capital approach. RESULTS: Follow-up was performed 2.7 years after aSAH (range 1.3-4.6). Favorable outcome was achieved in 114 of 150 patients (76%) and work recovery in 61 of 98 patients (62%) employed prior to aSAH. High-grade compared to low-grade aSAH resulted less frequently in favorable outcome (52% vs. 85%; p < 0.001) and work recovery (39% vs. 69%; p = 0.013). The total costs were € 344.277 (95% CI 268.383-420.171) per patient, mainly accounted to indirect costs (84%). The total costs increased with increasing degree of disability and were greater for high-grade compared to low-grade aSAH (€ 422.496 vs. € 329.193; p = 0.039). The effective costs per patient with favorable outcome were 2.1-fold greater for high-grade compared to low-grade aSAH (€ 308.625 vs. € 134.700). CONCLUSION: Favorable outcome can be achieved in a considerable proportion of high-grade aSAH patients, but costs are greater compared to low-grade aSAH. Further cost-effectiveness studies in the current era of aSAH management are needed.

Machine Learning Techniques for Personalized Detection of Epileptic Events in Clinical Video Recordings.

Continuous patient monitoring is essential to achieve an effective and optimal patient treatment in the intensive care unit. In the specific case of epilepsy it is the only way to achieve a correct diagnosis and a subsequent optimal medication plan if possible. In addition to automatic vital sign monitoring, epilepsy patients need manual monitoring by trained personnel, a task that is very difficult to be performed continuously for each patient. Moreover, epileptic manifestations are highly personalized even within the same type of epilepsy. In this work we assess two machine learning methods, dictionary learning and an autoencoder based on long short-term memory (LSTM) cells, on the task of personalized epileptic event detection in videos, with a set of features that were specifically developed with an emphasis on high motion sensitivity. According to the strengths of each method we have selected different types of epilepsy, one with convulsive behaviour and one with very subtle motion. The results on five clinical patients show a highly promising ability of both methods to detect the epileptic events as anomalies deviating from the stable/normal patient status.

Automated False Alarm Reduction in a Real-Life Intensive Care Setting Using Motion Detection.

BACKGROUND: Contemporary monitoring systems are sensitive to motion artifacts and cause an excess of false alarms. This results in alarm fatigue and hazardous alarm desensitization. To reduce the number of false alarms, we developed and validated a novel algorithm to classify alarms, based on automatic motion detection in videos. METHODS: We considered alarms generated by the following continuously measured parameters: arterial oxygen saturation, systolic blood pressure, mean blood pressure, heart rate, and mean intracranial pressure. The movements of the patient and in his/her surroundings were monitored by a camera situated at the ceiling. Using the algorithm, alarms were classified into RED (true), ORANGE (possibly false), and GREEN alarms (false, i.e., artifact). Alarms were reclassified by blinded clinicians. The performance was evaluated using confusion matrices. RESULTS: A total of 2349 alarms from 45 patients were reclassified. For RED alarms, sensitivity was high (87.0%) and specificity was low (29.6%) for all parameters. As the sensitivities and specificities for RED and GREEN alarms are interrelated, the opposite was observed for GREEN alarms, i.e., low sensitivity (30.2%) and high specificity (87.2%). As RED alarms should not be missed, even at the expense of false positives, the performance was acceptable. The low sensitivity for GREEN alarms is acceptable, as it is not harmful to tag a GREEN alarm as RED/ORANGE. It still contributes to alarm reduction. However, a 12.8% false-positive rate for GREEN alarms is critical. CONCLUSIONS: The proposed system is a step forward toward alarm reduction; however, implementation of additional layers, such as signal curve analysis, multiple parameter correlation analysis and/or more sophisticated video-based analytics are needed for improvement.

The relationship between IL-6, ET-1 and cerebral vasospasm, in experimental rabbit subarachnoid hemorrhage.

BACKGROUND: In subarachnoid hemorrhage (SAH), occurrence of cerebral vasospasm (CVS) mediated by endothelin (ET)-1 might be a result of a compartmental inflammatory response with interleukin (IL)-6 release. We aim to investigate the relationship between ET-1 and IL-6 in association of CVS. METHODS: A total of 24 New Zealand white rabbits where randomly allocated into 3 groups: SAH (N.=10), IL-6 (N.=10), and sham (N.=4). SAH was induced by a closed cranium extracranial-intracranial shunt model. In the IL-6 group, IL-6 was injected into the cisterna magna. CVS of the basilar artery was assessed by digital subtraction angiography. IL-6 and ET-1 concentrations were measured using enzyme-linked immunosorbent assay. Neuronal damage was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling. RESULTS: A significant increase between baseline (day 0) and follow-up (day 3) was found in CSF IL-6 levels of animals in the SAH and IL-6 group. There was a statistically significant correlation between IL-6 and ET-1 levels in the CSF (Pearson's r=0.454, P=0.003). CVS at day 3 was more pronounced in the SAH than in the IL-6 group: 26.0 ±7.2 % and 16.7 ±5.0 % respectively. TUNEL positive apoptotic neurons in the hippocampal formation were present in the SAH group and in a lesser degree in the IL-6 group. CONCLUSIONS: The results indicate that IL-6 triggered CVS after SAH is ET-1 dependent. IL-6 may be a target for new therapeutic approaches.

Natural Cerebral Aneurysm and Spontaneous Subarachnoid Hemorrhage in Mammals Other Than Man: Is There a Scope for Comparative Medicine?

BACKGROUND: Concepts that showed substantial efficacy in animal models of subarachnoid hemorrhage (SAH) often failed to improve outcome in humans with aneurysmal SAH. The concept of "comparative medicine," an open-minded comparison across species, might offer an alternative to the "constructed" animal models' approach. Naturally occurring diseases in animals might bear more similarity to human diseases than models. In this context, the question arises whether spontaneous intracranial aneurysms exist in animals or not, and whether they cause SAH or not. METHODS: A systematic literature search was performed. Only articles dealing with natural aneurysms and/or SAH of mammals other than man were included. All articles dealing with induced aneurysms and/or SAH were removed. RESULTS: Of 2812 screened articles, 9 articles describing natural intracranial aneurysms and/or SAH were found. In total 1979 individual animals of 29 species were examined. Natural intracranial aneurysms were described in 7 individual animals of 6 species. Spontaneous SAH was described in 3 species. In 1 chimpanzee, a ruptured intracranial aneurysm caused an SAH. Histological descriptions of the aneurysms were strikingly similar to those of humans. CONCLUSIONS: Although interesting and innovative, the concept of "comparative medicine" seems to be impracticable due to the seemingly ultralow incidence of natural aneurysmal SAH in mammals other than man. The answer to the question "why intracranial aneurysms are less common in animals despite the strong histological similarity of cerebral arteries" might be a key issue. Last but not least, primates likely matter in SAH-related research, as aneurysmal SAH occurs in primates.

Portable Infrared Pupillometer in Patients With Subarachnoid Hemorrhage: Prognostic Value and Circadian Rhythm of the Neurological Pupil Index (NPi).

BACKGROUND: Portable automated infrared pupillometry is becoming increasingly popular. To generate an objective reference base, the Neurological Pupil index (NPi) which combines different values of the pupillary light reflex is being introduced into clinical practice. In this explorative study, we examined different aspects of the NPi in relation to clinical severity and outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). MATERIALS AND METHODS: Patients with serial assessment of the NPi (NeurOptics pupillometer NPi-200, Irvine, CA) starting no later than day 2 after aSAH onset were included in the study. Relative numbers of pathologic NPi's, absolute NPi values, and their variances were compared according to aSAH clinical severity grade, functional outcome, and case fatality. The correlation between NPi and intracranial pressure, and NPi periodicity, were also examined. RESULTS: In total, 18 patients with 4456 NPi values were eligible for inclusion in the analysis. The general trend of the NPi over time reflected the course of the neurological illness. Mean NPi tended to be lower in patients with clinically severe compared with nonsevere aSAH (3.75±0.40 vs. 4.56±0.06; P=0.171), and in patients with unfavorable compared with favorable outcomes (3.64±0.48 vs. 4.50±0.08; P=0.198). The mean variance of the NPi was higher in patients with severe compared with nonsevere aSAH (0.49±0.17 vs. 0.06±0.02; P=0.025). Pathologic NPi values were recorded more frequently in patients with severe compared with nonsevere aSAH (16.3%±8.8% vs. 0.0%±0.0%; P=0.002), and in those with unfavorable compared with favorable outcomes (19.2%±10.6% vs. 0.7%±0.6%; P=0.017). NPi was inversely correlated with intracranial pressure (Spearman r=-0.551, P<0.001). We observed a circadian pattern of NPi's which was seemingly disrupted in patients with fatal outcome. CONCLUSIONS: On the basis of this preliminary study, the assessment of NPi by pupillometry is feasible and might complement multimodal neuromonitoring in patients with aSAH.

Systematic Review of In Vivo Animal Models of Subarachnoid Hemorrhage: Species, Standard Parameters, and Outcomes.

In preclinical models, modification of experimental parameters associated with techniques of inducing subarachnoid hemorrhage (SAH) can greatly affect outcomes. To analyze how parameter choice affects the relevance and comparability of findings, we systematically reviewed 765 experimental studies of in vivo animal SAH models (2000-2014). During the last decade, we found marked increases in publications using smaller species and models for simulating acute events after SAH. Overall, the fewer types of species and models used did not correlate with an increased standardization in the experimental characteristics and procedures. However, by species, commonly applied, reliable parameters for each experimental SAH technique were identified in mouse, rat, rabbit, and dog models. Our findings can serve as a starting point for discussion toward a more uniform performance of SAH experiments, development of preclinical SAH common data elements, and establishment of standardized protocols for multicenter preclinical trials.

Cell-Free Oxyhemoglobin in Cerebrospinal Fluid After Aneurysmal Subarachnoid Hemorrhage: Biomarker and Potential Therapeutic Target.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) is often complicated by the occurrence of delayed ischemic neurologic deficits (DIND), which impairs the clinical outcome of patients. The release of oxyhemoglobin (oxyHb) from lysing erythrocytes into cerebrospinal fluid (CSF) may critically contribute to the development of DIND. METHODS: Ventricular CSF of 18 high-grade (Fisher 3 and 4) aSAH patients was sampled daily from external ventricular drains between days 0 and 14 after bleeding. CSF was spectrophotometrically analyzed with precise quantification of cell-free oxyHb levels. RESULTS: OxyHb levels in CSF showed a delayed peak reaching the highest levels in the high-risk period for developing of DIND between days 3 and 14 after aneurysm rupture. Patients with DIND had a significantly higher cumulative oxyHb exposure within the first week after bleeding. CONCLUSIONS: OxyHb levels in CSF may be useful as a biomarker to predict DIND in aSAH patients. The contribution of oxyHb in CSF to the pathogenesis of DIND should be further investigated as a potential therapeutic target.

Decision tree analysis in subarachnoid hemorrhage: prediction of outcome parameters during the course of aneurysmal subarachnoid hemorrhage using decision tree analysis.

OBJECTIVEThe aim of this study was to create prediction models for outcome parameters by decision tree analysis based on clinical and laboratory data in patients with aneurysmal subarachnoid hemorrhage (aSAH).METHODSThe database consisted of clinical and laboratory parameters of 548 patients with aSAH who were admitted to the Neurocritical Care Unit, University Hospital Zurich. To examine the model performance, the cohort was randomly divided into a derivation cohort (60% [n = 329]; training data set) and a validation cohort (40% [n = 219]; test data set). The classification and regression tree prediction algorithm was applied to predict death, functional outcome, and ventriculoperitoneal (VP) shunt dependency. Chi-square automatic interaction detection was applied to predict delayed cerebral infarction on days 1, 3, and 7.RESULTSThe overall mortality was 18.4%. The accuracy of the decision tree models was good for survival on day 1 and favorable functional outcome at all time points, with a difference between the training and test data sets of < 5%. Prediction accuracy for survival on day 1 was 75.2%. The most important differentiating factor was the interleukin-6 (IL-6) level on day 1. Favorable functional outcome, defined as Glasgow Outcome Scale scores of 4 and 5, was observed in 68.6% of patients. Favorable functional outcome at all time points had a prediction accuracy of 71.1% in the training data set, with procalcitonin on day 1 being the most important differentiating factor at all time points. A total of 148 patients (27%) developed VP shunt dependency. The most important differentiating factor was hyperglycemia on admission.CONCLUSIONSThe multiple variable analysis capability of decision trees enables exploration of dependent variables in the context of multiple changing influences over the course of an illness. The decision tree currently generated increases awareness of the early systemic stress response, which is seemingly pertinent for prognostication.

A Posterior Oblique Approach to the Lumbar Disk Spaces, Vertebral Bodies, and Lumbar Plexus: A Cadaveric Feasibility Study.

STUDY DESIGN: A laboratory cadaveric study. OBJECTIVE: We aimed to demonstrate the feasibility of a posterior oblique approach, sharing the same advantages as the transpsoas technique while minimizing the risk of lumbar plexus or psoas muscle injuries. SUMMARY OF BACKGROUND DATA: The transpsoas approach for interbody fusion and corpectomy offers advantages over posterior and anterior approaches. However, possible risks include traumatization of the psoas muscle or lumbar plexus. METHODS: All lumbar disk spaces and vertebral bodies were exposed by a posterior oblique approach from left and right on a human cadaveric specimen. The exposure obtained and a step-by-step documentation of the procedure is outlined in detail. RESULTS: We were able to achieve wide exposure of all lumbar disk spaces and vertebral bodies above the L5/S1 disk space. Only the psoas muscle was retracted, and the lumbar plexus nerves were easily visualized and gently retracted. Sharp dissection was only required around the tip of the transverse processes. CONCLUSIONS: A posterior oblique approach seems to be less invasive than the transpsoas approach. Exposure of the anterior column structures above the iliac crest is comparable. The oblique approach offers direct access to the lumbar plexus and the extraforaminal segments of the nerve roots.

Magnetic Resonance Imaging Signal Characteristics of Medishield: Early Postoperative Profile in a Rabbit Interlaminotomy Model.

OBJECTIVE: Application of Medishield to the nerve root is common during spinal surgery to create a mechanical barrier from pain mediators and reduce scar formation. However, Medishield's signal characteristics on magnetic resonance imaging (MRI) have not yet been examined. METHODS: Microsurgical interlaminotomy was performed on 2 lower lumbar segments in 17 adult New Zealand white rabbits. After dural exposure, applications of 1 mL (autologous blood clot or Medishield) were randomized for each level. On postoperative days 1 through 3, various MRI sequences in 1.5T were performed including T1-weighted, T2-w, T1-gadolinium-weighted, susceptibility-weighted and turbo inversion recovery magnitude (TIRM) sequence. Signaling characteristics were analyzed by 3 blinded observers. Inter-rater agreement was calculated using Fleiss's kappa coefficient (κ). Positive and negative likelihood ratios in detecting Medishield by MRI were determined. RESULTS: Of 24 MRIs performed, TIRM sequence identified Medishield with the highest likelihood ratio. Medishield's positive likelihood ratio was highest (5.8) on postoperative day 1 with interobserver agreement of 93% (κ = 0.75); these rates declined to 2.5 and 1.4 on postoperative days 2 and 3 with interobserver agreements of 71% (κ = 0.43) and 83% (κ = 0.67), respectively. Medishield adherence was confirmed in each rabbit by histologic examinations. CONCLUSION: Understanding that radiologic detection of Medishield diminished over time as its signal characteristics became less distinguishable from a blood clot is essential in clinical practice. Medishield was detected on postoperative day 1 but not 2 days later after hemodynamic changes had occurred. These results may provide a guide for postoperative findings, such as differential diagnosis of hematoma.

Evaluation of a filament perforation model for mouse subarachnoid hemorrhage using 7.0 Tesla MRI.

The filament perforation model (FPM) in mice is becoming increasingly popular to elucidate the molecular pathogenesis of neuronal injury after subarachnoid hemorrhage (SAH). We evaluated brain MRI in a mouse FPM. A total of 28 male C57Bl/6J mice were used. Seventeen animals underwent SAH induction by FPM. In two animals, transient middle cerebral artery occlusion (MCAo) was induced. Nine mice served as controls. T1-weighted images (T1WI), T2-weighted images (T2WI), T2(∗)-weighted images (T2*WI) and apparent diffusion coefficient maps were acquired at day 0 and at various time points following SAH (range: day 1-6 after SAH). Cerebral blood flow (CBF) analysis by (14)C-iodoamphetamine ((14)C-IMP) autoradiography was conducted in nine animals. Hemorrhage could be best confirmed using T2*WI. The degree of hemorrhage varied. All animals evaluated for ⩾2days were hydrocephalic, which was best seen on T2WI. T2-hyperintensity of the corpus callosum and external capsule, indicating white matter (WM) injury, was present after SAH. Ventricle and WM injury volumes were statistically significantly higher at day 3 compared to day 0. Territorial ischemia was detectable in MCAo but not in SAH. Markedly hypointense cortical veins were visible in the hyperacute and delayed phase after SAH on T2*WI. The (14)C-IMP analysis indicated decreased CBF after SAH. MRI is feasible and useful in evaluating pathophysiological changes over time. T2*WI seems best for SAH detection and grading. The chronological change of hydrocephalus and WM injury could be analyzed. T2*WI illustrated specific signal changes of cortical veins, possibly caused by increased oxygen extraction fraction due to decreased CBF.