Management of intracranial hypertension

Point-of-care ultrasound of optic nerve sheath diameter to detect intracranial pressure in neurocritically ill children - A narrative review

The rapid diagnosis of increased intracranial pressure is urgently needed for therapeutic reasons in neurocritically ill children, however this can rarely be achieved without invasive procedures. Point-of-care ultrasound of the optic nerve sheath diameter has been proposed as a non-invasive and reliable means to detect increased intracranial pressure in adults. Accordingly, clinicians may be able to use this technique to initiate early treatment and monitor the effectiveness of treatment in conjunction with other clinical examination and diagnostic modalities. Two meta-analyses and a systematic review have been published on this topic in adults. However, data on the correlation between optic nerve sheath diameter and intracranial pressure in neurocritically ill children are scarce. The aim of this review was to briefly describe what is being measured with point-of-care ultrasound of the optic nerve sheath diameter, summarize the most recent findings from adult literature, and provide an update of current work in children.

Intercellular Sodium Regulates Repolarization in Cardiac Tissue with Sodium Channel Gain of Function

In cardiac myocytes, action potentials are initiated by an influx of sodium (Na⁺) ions via voltage-gated Na⁺ channels. Na⁺ channel gain of function (GOF), arising in both inherited conditions associated with mutation in the gene encoding the Na⁺ channel and acquired conditions associated with heart failure, ischemia, and atrial fibrillation, enhance Na⁺ influx, generating a late Na⁺ current that prolongs action potential duration (APD) and triggering proarrhythmic early afterdepolarizations (EADs). Recent studies have shown that Na⁺ channels are highly clustered at the myocyte intercalated disk, facilitating formation of Na⁺ nanodomains in the intercellular cleft between cells. Simulations from our group have recently predicted that narrowing the width of the intercellular cleft can suppress APD prolongation and EADs in the presence of Na⁺ channel mutations because of increased intercellular cleft Na⁺ ion depletion. In this study, we investigate the effects of modulating multiple extracellular spaces, specifically the intercellular cleft and bulk interstitial space, in a novel computational model and experimentally via osmotic agents albumin, dextran 70, and mannitol. We perform optical mapping and transmission electron microscopy in a drug-induced (sea anemone toxin, ATXII) Na⁺ channel GOF isolated heart model and modulate extracellular spaces via osmotic agents. Single-cell patch-clamp experiments confirmed that the osmotic agents individually do not enhance late Na⁺ current. Both experiments and simulations are consistent with the conclusion that intercellular cleft narrowing or expansion regulates APD prolongation; in contrast, modulating the bulk interstitial space has negligible effects on repolarization. Thus, we predict that intercellular cleft Na⁺ nanodomain formation and collapse critically regulates cardiac repolarization in the setting of Na⁺ channel GOF.

Intra-CSF AAV9 and AAVrh10 Administration in Nonhuman Primates: Promising Routes and Vectors for Which Neurological Diseases?

The identification of the most efficient method for whole central nervous system targeting that is translatable to humans and the safest route of adeno-associated virus (AAV) administration is a major concern for future applications in clinics. Additionally, as many AAV serotypes were identified for gene introduction into the brain and the spinal cord, another key to human gene-therapy success is to determine the most efficient serotype. In this study, we compared lumbar intrathecal administration through catheter implantation and intracerebroventricular administration in the cynomolgus macaque. We also evaluated and compared two AAV serotypes that are currently used in clinical trials: AAV9 and AAVrh10. We demonstrated that AAV9 lumbar intrathecal delivery using a catheter achieved consistent transgene expression in the motor neurons of the spinal cord and in the neurons/glial cells of several brain regions, whereas AAV9 intracerebroventricular delivery led to a consistent transgene expression in the brain. In contrast, AAVrh10 lumbar intrathecal delivery led to rare motor neuron targeting. Finally, we found that AAV9 efficiently targets respiratory and skeletal muscles after injection into the cerebrospinal fluid (CSF), which represents an outstanding new property that can be useful for the treatment of diseases affecting both the central nervous system and muscle.

Intracranial pressure, brain morphology and cognitive outcome in children with sagittal craniosynostosis

BACKGROUND

Patients with sagittal craniosynostosis are at increased risk of developing raised intracranial pressure (ICP) and neurocognitive deficiencies such as reduced attention, planning, speech, behavioural and learning disabilities.

AIM

To determine if the existing literature supports a correlation between elevated ICP and negative cognitive outcome in patients with sagittal craniosynostosis. Secondly, to investigate if the risk of developing neurocognitive deficiencies can be explained by changes in brain morphology in this patient category.

METHODS

Systematic literature review in PubMed.

RESULTS

A total of 190 publications were reviewed to determine a possible correlation between raised ICP and cognitive outcome, of which four were included in the study. No significant association was found. Forty-four publications on brain morphology in sagittal craniosynostosis were identified, of which 11 were included in the review. Clear evidence of morphologic changes in multiple areas of the brains of sagittal craniosynostosis patients was found in the literature.

CONCLUSION

The existing literature does not support an association between increased ICP and negative global cognitive outcome measures in patients with sagittal craniosynostosis. Brain morphology is altered in areas related to neurocognition and language in the same patient group. These changes might play a role in the development of neurocognitive deficiencies, though no definitive link is yet established, and further investigation is warranted.

Imaging effects of hyperosmolality on individual tricellular junctions

The use of hyperosmolar agents (osmotherapy) has been a major treatment for intracranial hypertension, which occurs frequently in brain diseases or trauma. However, side-effects of osmotherapy on the brain, especially on the blood-brain barrier (BBB) are still not fully understood. Hyperosmolar conditions, termed hyperosmolality here, are known to transiently disrupt the tight junctions (TJs) at the endothelium of the BBB resulting in loss of BBB function. Present techniques for evaluation of BBB transport typically reveal aggregated responses from the entirety of BBB transport components, with little or no opportunity to evaluate heterogeneity present in the system. In this study, we utilized potentiometric-scanning ion conductance microscopy (P-SICM) to acquire nanometer-scale conductance maps of Madin-Darby Canine Kidney strain II (MDCKII) cells under hyperosmolality, from which two types of TJs, bicellular tight junctions (bTJs) and tricellular tight junctions (tTJs), can be visualized and differentiated. We discovered that hyperosmolality leads to increased conductance at tTJs without significant alteration in conductance at bTJs. To quantify this effect, an automated computer vision algorithm was designed to extract and calculate conductance components at both tTJs and bTJs. Additionally, lowering Ca2+ concentration in the bath facilitates tTJ disruption under hyperosmolality. Strengthening tTJ structure by overexpressing immunoglobulin-like domain-containing receptor 1 (ILDR1) protein abrogates the effect of hyperosmolality. We posit that osmotic stress physically disrupts tTJ structure, as evidenced by super-resolution microscopy. Findings from this study not only provide a high-resolution view of TJ structure and function, but also can inform current osmotherapy and drug delivery strategies for brain diseases.

Forecasting intracranial hypertension using multi-scale waveform metrics

OBJECTIVE

Acute intracranial hypertension is an important risk factor of secondary brain damage after traumatic brain injury. Hypertensive episodes are often diagnosed reactively, leading to late detection and lost time for intervention planning. A pro-active approach that predicts critical events several hours ahead of time could assist in directing attention to patients at risk.

APPROACH

We developed a prediction framework that forecasts onsets of acute intracranial hypertension in the next 8 h. It jointly uses cerebral auto-regulation indices, spectral energies and morphological pulse metrics to describe the neurological state of the patient. One-minute base windows were compressed by computing signal metrics, and then stored in a multi-scale history, from which physiological features were derived.

MAIN RESULTS

Our model predicted events up to 8 h in advance with an alarm recall rate of 90% at a precision of 30% in the MIMIC-III waveform database, improving upon two baselines from the literature. We found that features derived from high-frequency waveforms substantially improved the prediction performance over simple statistical summaries of low-frequency time series, and each of the three feature classes contributed to the performance gain. The inclusion of long-term history up to 8 h was especially important.

SIGNIFICANCE

Our results highlight the importance of information contained in high-frequency waveforms in the neurological intensive care unit. They could motivate future studies on pre-hypertensive patterns and the design of new alarm algorithms for critical events in the injured brain.

International survey of neurosurgical anesthesia (iSonata) : An international survey of current practices in neurosurgical anesthesia

BACKGROUND

No standardized recommendations have been currently defined for anesthesia management of patients undergoing elective intracranial surgery. It can therefore be assumed that international clinical institutions have diverging approaches or standard operating procedures (SOP) which determine the type of general anesthesia, hemodynamic management, neuromuscular blockade, implementation of hypothermia and postoperative patient care.

OBJECTIVE

This international survey aimed to assess perioperative patient management during elective intracranial procedures. This survey was performed from February to October 2018 and 311 neurosurgical, maximum care centers across 19 European countries were contacted. The aim was to evaluate the anesthesia management to provide relevant data of neuroanesthesia practices across European centers. The survey differentiated between vascular and non-vascular as well as supratentorial and infratentorial procedures.

RESULTS

A total of 109 (35.0%) completed questionnaires from 15 European countries were analyzed. The results illustrated that total intravenous anesthesia was most commonly implemented during elective intracranial procedures (83.8%). All centers performed endotracheal intubation prior to major intracranial surgery (100%). Central venous lines were placed in 63.3% of cases. Moderate intraoperative hypothermia was carried out in 12.8% of the procedures, especially during vascular supratentorial and infratentorial surgery. A neuromuscular blockade during surgery was implemented in 74.1% of patients. Assessment of the neuromuscular junction was performed in 59.2% of cases, 76.7% of patients were immediately extubated in the operating room. 84.7% of these patients were directly transferred to a monitoring ward or an intensive care unit (ICU) and 55.1% of ventilated patients were transferred directly to an ICU.

CONCLUSION

The data demonstrate that many aspects of anesthesia management during elective intracranial surgery vary between European institutions. The data also suggest that a broad consensus exists regarding the implementation of total intravenous anesthesia, airway management (endotracheal intubation), the implementation of urinary catheters, large bore peripheral venous lines and the broad availability of cross-matched red blood cell concentrates. Nevertheless, anesthesia management (e.g. central venous catheterization, moderate hypothermia, neuromuscular monitoring) is still handled differently across many European institutions. A lack of standardized guidelines defining anesthetic management in patients undergoing intracranial procedures could explain this variability. Further studies could help establish optimal anesthesia management for these patients. This in turn could help in the development of national and international guidelines and SOPs which could define optimal management strategies for intracranial procedures.

Hypertonic saline versus other intracranial pressure-lowering agents for people with acute traumatic brain injury

BACKGROUND

Increased intracranial pressure has been shown to be strongly associated with poor neurological outcomes and mortality for patients with acute traumatic brain injury. Currently, most efforts to treat these injuries focus on controlling the intracranial pressure. Hypertonic saline is a hyperosmolar therapy that is used in traumatic brain injury to reduce intracranial pressure. The effectiveness of hypertonic saline compared with other intracranial pressure-lowering agents in the management of acute traumatic brain injury is still debated, both in the short and the long term.

OBJECTIVES

To assess the comparative efficacy and safety of hypertonic saline versus other intracranial pressure-lowering agents in the management of acute traumatic brain injury.

SEARCH METHODS

We searched Cochrane Injuries' Specialised Register, CENTRAL, PubMed, Embase Classic+Embase, ISI Web of Science: Science Citation Index and Conference Proceedings Citation Index-Science, as well as trials registers, on 11 December 2019. We supplemented these searches with searches of four major Chinese databases on 19 September 2018. We also checked bibliographies, and contacted trial authors to identify additional trials.

SELECTION CRITERIA

We sought to identify all randomised controlled trials (RCTs) of hypertonic saline versus other intracranial pressure-lowering agents for people with acute traumatic brain injury of any severity. We excluded cross-over trials as incompatible with assessing long-term outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results to identify potentially eligible trials and extracted data using a standard data extraction form. Outcome measures included: mortality at end of follow-up (all-cause); death or disability (as measured by the Glasgow Outcome Scale (GOS)); uncontrolled intracranial pressure (defined as failure to decrease the intracranial pressure to target and/or requiring additional intervention); and adverse events e.g. rebound phenomena; pulmonary oedema; acute renal failure during treatment).

MAIN RESULTS

Six trials, involving data from 287 people, met the inclusion criteria. The majority of participants (91%) had a diagnosis of severe traumatic brain injury. We had concerns about particular domains of risk of bias in each trial, as physicians were not reliably blinded to allocation, two trials contained participants with conditions other than traumatic brain injury and in one trial, we had concerns about missing data for important outcomes. The original protocol was available for only one trial and other trials (where registered) were registered retrospectively. Meta-analysis for both the primary outcome (mortality at final follow-up) and for 'poor outcome' as per conventionally dichotomised GOS criteria, was only possible for two trials. Synthesis of long-term outcomes was inhibited by the fact that two trials ceased data collection within two hours of a single bolus dose of an intracranial pressure-lowering agent and one at discharge from the intensive care unit (ICU). Only three trials collected data after participants were released from hospital, one of which did not report mortality and reported a 'poor outcome' by GOS criteria in an unconventional way. Substantial missing data in a key trial meant that in meta-analysis we report 'best-case' and 'worst-case' estimates alongside available case analysis. In no scenario did we discern a clear difference between treatments for either mortality or poor neurological outcome. Due to variation in modes of drug administration (including whether it followed or did not follow cerebrospinal fluid (CSF) drainage, as well as different follow-up times and ways of reporting changes in intracranial pressure, as well as no uniform definition of 'uncontrolled intracranial pressure', we did not perform meta-analysis for this outcome and report results narratively, by individual trial. Trials tended to report both treatments to be effective in reducing elevated intracranial pressure but that hypertonic saline had increased benefits, usually adding that pretreatment factors need to be considered (e.g. serum sodium and both system and brain haemodynamics). No trial provided data for our other outcomes of interest. We consider evidence quality for all outcomes to be very low, as assessed by GRADE; we downgraded all conclusions due to imprecision (small sample size), indirectness (due to choice of measurement and/or selection of participants without traumatic brain injury), and in some cases, risk of bias and inconsistency. Only one of the included trials reported data on adverse effects; a rebound phenomenon, which was present only in the comparator group (mannitol). None of the trials reported data on pulmonary oedema or acute renal failure during treatment. On the whole, trial authors do not seem to have rigorously sought to collect data on adverse events.

AUTHORS' CONCLUSIONS

This review set out to find trials comparing hypertonic saline to a potential range of other intracranial pressure-lowering agents, but only identified trials comparing it with mannitol or mannitol in combination with glycerol. Based on limited data, there is weak evidence to suggest that hypertonic saline is no better than mannitol in efficacy and safety in the long-term management of acute traumatic brain injury. Future research should be comprised of large, multi-site trials, prospectively registered, reported in accordance with current best practice. Trials should investigate issues such as the type of traumatic brain injury suffered by participants and concentration of infusion and length of time over which the infusion is given.

Idiopathic Intracranial Hypertension: Shunt Failure and the Role of Obesity

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a chronic condition characterized by raised intracranial pressure in the absence of a known etiology. IIH typically presents in overweight women of childbearing age. Surgical intervention for IIH involves diversion of cerebrospinal fluid, often by the placement of a shunt. Experience suggests higher shunt failure rates in patients with IIH than shunts placed for other etiologies. Here we sought to both establish and compare failure rates for IIH and non-IIH shunts and to examine association with body mass index (BMI).

METHODS

This study was a single-center retrospective consecutive cohort over a 13-year period. There were 1264 non-IIH patients and 116 patients with IIH included in the study. This was a retrospective analysis of time to shunt failure using Kaplan-Meier methods for IIH and non-IIH shunts. Secondary analysis of BMI, shunt type, and sex on IIH shunt failure was also conducted.

RESULTS

The median time to failure of the initial IIH shunt was 22.9 months (interquartile range [IQR], 4-55) compared with 57 months (IQR, 12-87) in non-IIH shunts (P < 0.001; 95% confidence interval, 58.6-233.6). In the IIH group, the median shunt survival for BMI above the healthy range (18.5-25 kg/m²) was 18 months relative to 44 months for those with a healthy BMI.

CONCLUSIONS

Our study suggests that in IIH, relative to hydrocephalus of other causes, shunts have higher failure rates and often require more frequent revisions. Higher shunt failure rates in patients with IIH may be associated with an unhealthy BMI.

Hypertonic saline versus other intracranial pressure-lowering agents for people with acute traumatic brain injury

BACKGROUND

Increased intracranial pressure (ICP) has been shown to be strongly associated with poor neurological outcomes and mortality for patients with acute traumatic brain injury (TBI). Currently, most efforts to treat these injuries focus on controlling the ICP. Hypertonic saline (HTS) is a hyperosmolar therapy that is used in traumatic brain injury to reduce intracranial pressure. The effectiveness of HTS compared with other ICP-lowering agents in the management of acute TBI is still debated, both in the short and the long term.

OBJECTIVES

To assess the comparative efficacy and safety of hypertonic saline versus other ICP-lowering agents in the management of acute TBI.

SEARCH METHODS

We searched the Cochrane Injuries Group's Specialised Register, The Cochrane Library, PubMed, Embase Classic+Embase (OvidSP), ISI Web of Science: Science Citation Index and Conference Proceedings Citation Index-Science, as well as trials registers, on 11 December 2019. We supplemented these searches using four major Chinese databases on 19 September 2018. We also checked bibliographies, and contacted study authors to identify additional studies.

SELECTION CRITERIA

We sought to identify all randomised controlled trials (RCTs) of HTS versus other intracranial pressure-lowering agents for people with acute TBI of any severity. We excluded cross-over trials as incompatible with assessing long term outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results to identify potentially eligible trials and extracted data using a standard data extraction form. Outcome measures included: mortality at end of follow-up (all-cause); death or disability (as measured by the Glasgow Outcome Scale (GOS)); uncontrolled ICP (defined as failure to decrease the ICP to target and/or requiring additional intervention); and adverse events (AEs) (e.g. rebound phenomena; pulmonary oedema; acute renal failure during treatment).

MAIN RESULTS

Six trials, involving data from 295 people, met the inclusion criteria. The majority of participants (89%) had a diagnosis of severe TBI. We had concerns about particular domains of risk of bias in each trial, as physicians were not reliably blinded to allocation, two trials contained participants with conditions other than TBI and in one trial, there were concerns about missing data for important outcomes. The original protocol was available for only one study and other trials (where registered) were registered retrospectively. Meta-analysis for both the primary outcome (mortality at final follow up) and for 'poor outcome' as per conventionally dichotomised GOS criteria, was only possible for two studies. Synthesis of long-term outcomes was inhibited by the fact that two ceased data collection within two hours of a single bolus dose of an ICP-lowering agent and one at discharge from ICU. Only three studies collected data after release from hospital. Due to variation in modes of drug administration, follow-up times, and ways of reporting changes in ICP, as well as no uniform definition of 'uncontrolled ICP', we did not perform meta-analysis for this outcome and report results narratively, by individual trial. Trials tended to report both treatments to be effective in reducing elevated ICP but that HTS had increased benefits, usually adding that pretreatment factors need to be considered (e.g. serum sodium and both system and brain hemodynamics). No trial provided data for our other outcomes of interest. Evidence for all outcomes is considered very low, as assessed by GRADE. All conclusions were downgraded due to imprecision (small sample size), indirectness (due to choice of measurement and/or selection of patients without TBI), and in some cases, risk of bias and inconsistency. Only one of the included trials reported data on adverse effects (AEs) - a rebound phenomenon, which was present only in the comparator group (mannitol). No data were reported on pulmonary oedema or acute renal failure during treatment. On the whole, investigators do not seem to have rigorously sought to collect data on AEs.

AUTHORS' CONCLUSIONS

This review set out to find trials comparing HTS to a potential range of other ICP-lowering agents, but only identified trials comparing it with mannitol or mannitol in combination with glycerol. Based on limited data, there is weak evidence to suggest that HTS is no better than mannitol in efficacy and safety in the long-term management of acute TBI. Future research should be comprised of large, multi-site trials, prospectively registered, reported in accordance with current best practice. Issues such as the type of TBI suffered by participants and concentration of infusion and length of time over which the infusion is given should be investigated.

Nursing Interventions for Patients with Intracranial Hypertension: Integrative Literature Review

Objective: the study sought to identify, in national and international publications, the principal Nursing interventions aimed at patients with intracranial hypertension. Materials and Method: integrative literature review with search in LILACS, PubMed, Scopus, Web of Science, Cinahal, and Google Scholar databases, from 2013 to 2018. Results: the sample was comprised of seven articles fulfilling the inclusion criteria. Two thematic categories were established for the Nursing interventions aimed at patients with intracranial hypertension: cognitive skills and clinical reasoning, necessary to control neuro-physiological parameters and prevent intracranial hypertension, and evidence-based practices to improve care for neuro-critical patients. Conclusions: intracranial hypertension is an event of great clinical impact, whose complications can be minimized and control through specific Nursing interventions that encompass control of neuro-physiological and hemodynamic parameters and prevention of increased intracranial pressure related with the performance of procedures by the Nursing staff.

Quantification of Iodine Leakage on Dual-Energy CT as a Marker of Blood-Brain Barrier Permeability in Traumatic Hemorrhagic Contusions: Prediction of Surgical Intervention for Intracranial Pressure Management

BACKGROUND AND PURPOSE

Hemorrhagic contusions are associated with iodine leakage. We aimed to identify quantitative iodine-based dual-energy CT variables that correlate with the type of intracranial pressure management.

MATERIALS AND METHODS

Consecutive patients with contusions from May 2016 through January 2017 were retrospectively analyzed. Radiologists, blinded to the outcomes, evaluated CT variables from unenhanced admission and short-term follow-up head dual-energy CT scans obtained after contrast-enhanced whole-body CT. Treatment intensity of intracranial pressure was broadly divided into 2 groups: those managed medically and those managed surgically. Univariable analysis followed by logistic regression was used to develop a prediction model.

RESULTS

The study included 65 patients (50 men; median age, 48 years; Q1 to Q3, 25-65.5 years). Twenty-one patients were managed surgically (14 by CSF drainage, 7 by craniectomy). Iodine-based variables that correlated with surgical management were higher iodine concentration, pseudohematoma volume, iodine quantity in pseudohematoma, and iodine quantity in contusions. The regression model developed after inclusion of clinical variables identified 3 predictor variables: postresuscitation Glasgow Coma Scale (adjusted OR = 0.55; 95% CI, 0.38-0.79; P = .001), age (adjusted OR = 0.9; 95% CI, 0.85-0.97; P = .003), and pseudohematoma volume (adjusted OR = 2.05; 95% CI, 1.1-3.77; P = .02), which yielded an area under the curve of 0.96 in predicting surgical intracranial pressure management. The 2 predictors for craniectomy were age (adjusted OR = 0.89; 95% CI, 0.81-0.99; P = .03) and pseudohematoma volume (adjusted OR = 1.23; 95% CI, 1.03-1.45; P = .02), which yielded an area under the curve of 0.89.

CONCLUSIONS

Quantitative iodine-based parameters derived from follow-up dual-energy CT may predict the intensity of intracranial pressure management in patients with hemorrhagic contusions.

Novel index for predicting mortality during the first 24 hours after traumatic brain injury

OBJECTIVE

Failure of cerebral autoregulation and subsequent hypoperfusion is common during the acute phase of traumatic brain injury (TBI). The cerebrovascular pressure-reactivity index (PRx) indirectly reflects cerebral autoregulation and has been used to derive optimal cerebral perfusion pressure (CPP). This study provides a method for the use of a combination of PRx, CPP, and intracranial pressure (ICP) to better evaluate the extent of cerebral hypoperfusion during the first 24 hours after TBI, allowing for a more accurate prediction of mortality risk.

METHODS

Continuous ICP and arterial blood pressure (ABP) signals acquired from 295 TBI patients during the first 24 hours after admission were retrospectively analyzed. The CPP at the lowest PRx was determined as the optimal CPP (CPPopt). The duration of a severe hypoperfusion event (dHP) was defined as the cumulative time that the PRx was > 0.2 and the CPP was < 70 mm Hg with the addition of intracranial hypertension (ICP > 20 or > 22 mm Hg). The outcome was determined as 6-month mortality.

RESULTS

The cumulative duration of PRx > 0.2 and CPP < 70 mm Hg exhibited a significant association with mortality (p < 0.001). When utilized with basic clinical information available during the first 24 hours after admission (i.e., Glasgow Coma Scale score, age, and mean ICP), a dHP > 25 minutes yielded a significant predictive capacity for mortality (p < 0.05, area under the curve [AUC] = 0.75). The parameter was particularly predictive of mortality for patients with a mean ICP > 20 or > 22 mm Hg (AUC = 0.81 and 0.87, respectively).

CONCLUSIONS

A short duration (25 minutes) of severe hypoperfusion, evaluated as lowered CPP during worsened cerebrovascular reactivity during the 1st day after TBI, is highly indicative of mortality.

Machine Learning and Artificial Intelligence in Neurocritical Care: a Specialty-Wide Disruptive Transformation or a Strategy for Success

PURPOSE OF REVIEW

Neurocritical care combines the complexity of both medical and surgical disease states with the inherent limitations of assessing patients with neurologic injury. Artificial intelligence (AI) has garnered interest in the basic management of these complicated patients as data collection becomes increasingly automated.

RECENT FINDINGS

In this opinion article, we highlight the potential AI has in aiding the clinician in several aspects of neurocritical care, particularly in monitoring and managing intracranial pressure, seizures, hemodynamics, and ventilation. The model-based method and data-driven method are currently the two major AI methods for analyzing critical care data. Both are able to analyze the vast quantities of patient data that are accumulated in the neurocritical care unit. AI has the potential to reduce healthcare costs, minimize delays in patient management, and reduce medical errors. However, these systems are an aid to, not a replacement for, the clinician's judgment.

Inconsistency in Reporting Variables Related to Intracranial Pressure Measurement in Scientific Literature

PURPOSE

To assess whether the collection and communication of intracranial pressure (ICP) values were standardized and reproducible.

METHODS

Integrative review of clinical trials (n = 357) reporting ICP as a variable.

RESULTS

Only 24.1% of studies reported adequate data required for replication. Of the 357 reports, 342 provided information about the design, 274 discussed sampling strategy, 294 identified the ICP device type, 312 provided a unit of measure, 121 provided anatomical localization for measuring ICP, and 83 provided information about patient positioning.

CONCLUSIONS

The majority of literature evaluated did not provide enough data for replication of results. Measuring and reporting ICP in the scientific literature is not standardized. A uniform standard would strengthen the quality of the evidence in neurocritical care and neurosurgical literature and better establish clinical guidelines for ICP management in neurologically injured patients.

Semi-quantitative Cough Strength Score as a Predictor for Extubation Outcome in Traumatic Brain Injury: A Prospective Observational Study

BACKGROUND

Between 25 and 40% of extubated patients with traumatic brain injury (TBI) in the intensive care unit at our hospital (Assiut University Hospital-Assiut-Egypt) require reintubation. This reflects the importance of developing better criteria for predicting successful extubation in TBI. We evaluated the accuracy of semi-quantitative cough strength score (SCSS) and Glasgow coma scale (GCS) in predicting extubation outcomes in TBI.

METHODS

This prospective observational study included patients (18-65 years), with TBI on mechanical ventilation more than 24 h who were ready to be weaned off. Three tools were used. Tool I: Patient assessment sheet, this tool used to assess socio-demographic and clinical data of patients. Tool II: Semi-quantitative cough strength score (0-5). Tool III: Factors affecting successful extubation, this tool used to confirm the presence or absence of factors that can interfere with the results of extubation outcomes. After extubation, patient was followed up for 72 h to check for extubation success. Multivariate logistic binary regression test was used to calculate odds ratio for different clinical data collected before extubation as independent factors and successful extubation as a dependent factor.

RESULTS

Among 80 patients of mean age 40.6 (± 16.1), 34% were female, median admission GCS was 8 (4-13), extubation occurred on mean post-injury day 6.5 (± 4), and 46.3% required reintubation. Successfully extubated patients had higher semi-quantitative cough scores and GCS. 81.3% patients with SCSS 5 were successfully extubated, while all patients with SCSS 0 were reintubated. All patients with GCS 15 were successfully extubated, and all patients with GCS < 12 required intubation.

CONCLUSION

SCSS has shown promise in predicting successful extubation in TBI.

Familial Intracranial Hypertension in 2 Brothers With PTEN Mutation: Expansion of the Phenotypic Spectrum

PTEN (Phosphatase and Tensin Homolog on chromosome TEN) encodes a vastly expressed tumor suppressor protein that antagonizes the PI3 K signaling pathway and alters the MTOR pathway. Mutations in PTEN have been described in association with a number of syndromes including PTEN hamartoma-tumor syndrome, macrocephaly/autism, and juvenile polyposis of infancy. Although there is a wide variability in the clinical and radiologic presentations of PTEN-related phenotypes, the most consistent features include macrocephaly and increased tumorigenesis. Intracranial hypertension may be idiopathic or secondary to multiple etiologies. We describe 2 siblings harboring a PTEN mutation who presented with macrocephaly and intracranial hypertension. Repeat brain MRIs were normal in both. Acetazolamide treatment normalized intracranial pressure, but several trials of medication tapering led to recurrence of intracranial hypertension symptoms. The clinical presentation of our patients expands the PTEN-related phenotypes. We discuss the possible pathophysiology in view of PTEN function.

Intracranial Hemorrhage and Intracranial Hypertension

Central nervous system hemorrhage has multiple pathophysiologic etiologies, including intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and traumatic brain injury (TBI). Given the nuances intrinsic to each of these etiologies and pathophysiologic processes, optimal blood pressure varies significantly and depends on type of hemorrhage and individual characteristics. This article reviews the most current evidence regarding blood pressure targets and provides guidance on reversal of anticoagulation for TBI, ICH, and SAH. It also describes the assessment, optimal therapeutic targets, and interventions to treat intracranial hypertension that can result from TBI, ICH, or SAH.

Validity and reliability of pocket-sized ultrasound devices in measurement of optic nerve sheath diameter in ICU patients

The measurement of the optic nerve sheath diameter (ONSD) by ultrasonography (USG) is particularly important for intracranial pressure (ICP) monitoring when invasive measurements are not possible or are contraindicated. Standard USG (SUDs) devices can be bulky and may break down the workflow. The validity and reliability of pocket-sized USG devices (PSUDs) compared to SUDs for ONSD measurement has not been investigated, yet. We compared the reliability and validity of PSUDs with SUDs for ONSD measurement. 35 patients were included in the study. ONSD measurements with PSUDs and SUDs were performed by two clinicians as three different measurements in both sagittal and transverse axis of the eye. There was agreement between mean transverse ONSD (mtONSD), mean sagittal ONSD (msONSD), and mean ONSD(mONSD) values measured with each device according to Bland-Altman test (p = 0.166, p = 0.135, p = 0.066, respectively) with no proportional bias (p = 0.544, p = 0.868, p = 0.929, respectively). Intraclass correlation coefficients (ICC) were found to be greater than 0.7 for mtONSD, msONSD, and mONSD values measured by SUD (ICC = 0.790, ICC = 0.817, and ICC = 0.844, respectively). Similarly, for mtONSD, msONSD, and mONSD values measured by PSUD, ICC were found greater than 0.7 (ICC = 0.763, ICC = 0.814, and ICC = 0.843, respectively). There was no statistically significant difference between mtONSD and msONSD (p = 0.441 for SUD and p = 0.893 for PSUD). There was a good correlation between mtONSD and msONSD (r = 0.767 for SUD and r = 0.816 for PSUD). The total variance between three different measurements in the transverse and sagittal axis was ± 0.6 mm. PSUDs can be used with similar validity and reliability as SUDs for ONSD measurement.

Endovascular treatment of cerebral vasospasm after subarachnoid hemorrhage

Objective

Delayed cerebral ischemia (DCI) is strongly associated with poor outcome after subarachnoid hemorrhage (SAH). Cerebral vasospasm is a major contributor to DCI and requires special attention. To evaluate the effect of vasospasm management on SAH outcome, we performed a pooled analysis of 2 observational SAH cohorts.

Materials

Data from 2 institutional databases with consecutive patients with SAH treated between 2005 and 2012 were pooled. The effect of 2 institutional standards of conservative and endovascular vasospasm treatment (EVT) on the rates of DCI (new cerebral infarcts not visible on the post-treatment imaging) and unfavorable outcome (modified Rankin Scale score >2) at 6 months follow-up was analyzed.

Results

The final analysis included 1,057 patients with SAH. There was no difference regarding demographic (age and sex), clinical (Hunt & Hess grades, acute hydrocephalus, treatment modality, and infections), and radiographic (Fisher grades and aneurysm location) characteristics of the populations. However, there was a significant difference in the rate (24.4% [121/495] vs 14.4% [81/562], p < 0.0001) and timing (first treatment on day 6 vs 8.9 after SAH, p < 0.0001) of EVT. The rates of DCI (20.8% vs 29%, p = 0.0001) and unfavorable outcome (44% vs 50.6%, p = 0.04) were lower in the cohort with more frequent and early EVT. Multivariate analysis confirmed independent effect of EVT standard on DCI risk and outcome.

Conclusions

A preventive strategy utilizing frequent and early EVT seems to reduce the risk of DCI in patients with SAH and improve their functional outcome. We recommend prospective evaluation of the value of preventive EVT strategy on SAH.

Classification of evidence

This study provides Class III evidence that for patients with SAH, a frequent and early EVT to treat vasospasm reduces the risk of DCI and improves functional outcome.

Artificial intelligence in neurocritical care

BACKGROUND

Neurocritical care combines the management of extremely complex disease states with the inherent limitations of clinically assessing patients with brain injury. As the management of neurocritical care patients can be immensely complicated, the automation of data-collection and basic management by artificial intelligence systems have garnered interest.

METHODS

In this opinion article, we highlight the potential artificial intelligence has in monitoring and managing several aspects of neurocritical care, specifically intracranial pressure, seizure monitoring, blood pressure, and ventilation.

RESULTS

The two major AI methods of analytical technique currently exist for analyzing critical care data: the model-based method and data driven method. Both of these methods have demonstrated an ability to analyze vast quantities of patient data, and we highlight the ways in which these modalities of artificial intelligence might one day play a role in neurocritical care.

CONCLUSIONS

While none of these artificial intelligence systems are meant to replace the clinician's judgment, these systems have the potential to reduce healthcare costs and errors or delays in medical management.

Contemporary Management of Increased Intraoperative Intracranial Pressure: Evidence-Based Anesthetic and Surgical Review

Increased intracranial pressure (ICP) is frequently encountered in the neurosurgical setting. A multitude of tactics exists to reduce ICP, ranging from patient position and medications to cerebrospinal fluid diversion and surgical decompression. A vast amount of literature has been published regarding ICP management in the critical care setting, but studies specifically tailored toward the management of intraoperative acute increases in ICP or brain bulk are lacking. Compartmentalizing the intracranial space into blood, brain tissue, and cerebrospinal fluid and understanding the numerous techniques available to affect these individual compartments can guide the surgical team to quickly identify increased brain bulk and respond appropriately. Rapidly instituting measures for brain relaxation in the operating room is essential in optimizing patient outcomes. Knowledge of the efficacy, rapidity, feasibility, and risks of the various available interventions can aid the team to properly tailor their approach to each individual patient. In this article, we present the first evidence-based review of intraoperative management of ICP and brain bulk.

Relationship between intracranial pressure and antifungal agents levels in the CSF of patients with cryptococcal meningitis

The purpose of this study was to evaluate the influence of intracranial hypertension in the cerebrospinal fluid (CSF) levels of amphotericin B and fluconazole levels of patients with cryptococcal meningitis. CSF samples and intracranial pressure were obtained by means of routine punctures performed at days 1, 7, and 14 of therapy, respectively. Amphotericin B and fluconazole CSF levels were measured by HPLC method as previously described. The minimum inhibitory concentration for amphotericin B, fluconazole, 5΄flucytosine, and voriconazole of each Cryptococcus isolate was performed according to CLSI. The predominant Cryptococcus species found was C. neoformans, and the major underlying condition was AIDS. Only one CSF sample had a detectable level for amphotericin B during the 14 days of therapy. Fluconazole CSF levels progressively increased from day 1 to day 14 of therapy for most cases. Fluconazole levels in the CSF were above the minimum inhibitory concentrations (MICs) for Cryptococcus during the initial 14 days of antifungal therapy. Variations of intracranial pressure did not affect amphotericin B and fluconazole levels in the CSF. The generalized estimating correlation (GEE) and Spearman correlation test (SCT) showed no significant correlation between the amphotericin B or fluconazole concentrations in the CSF and intracranial pressure (P = .953 and P = .093, respectively for GEE test and P = .477 and P = .847, respectively, for SCT). Combination therapy of amphotericin B with fluconazole was effective in 60% of the patients considering CSF cultures were negative in 9 of 15 patients after 14 days of therapy. Further studies are necessary to evaluate the role of intracranial hypertension on the therapeutic efficacy of different antifungal agents in patients with cryptococcal meningitis.

Early prediction of neurological outcome after barbiturate coma therapy in patients undergoing brain tumor surgery

After a difficult brain tumor surgery, refractory intracranial hypertension (RICH) may occur due to residual tumor or post-operative complications such as hemorrhage, infarction, and aggravated brain edema. We investigated which predictors are associated with prognosis when using barbiturate coma therapy (BCT) as a second-tier therapy to control RICH after brain tumor surgery. The study included adult patients who underwent BCT after brain tumor surgery between January 2010 and December 2016. The primary outcome was neurological status upon hospital discharge, which was assessed using the Glasgow Outcome Scale (GOS). In the study period, 4,296 patients underwent brain tumor surgery in total. Of these patients, BCT was performed in 73 patients (1.7%). Among these 73 patients, 56 (76.7%) survived to discharge and 25 (34.2%) showed favorable neurological outcomes (GOS scores of 4 and 5). Invasive monitoring of intracranial pressure (ICP) was performed in 60 (82.2%) patients, and revealed that the maximal ICP within 6 h after BCT was significantly lower in patients with favorable neurological outcome as well as in survivors (p = 0.008 and p = 0.028, respectively). Uncontrolled RICH (ICP ≥ 22 mm Hg within 6 h of BCT) was an important predictor of mortality after BCT (adjusted hazard ratio 12.91, 95% confidence interval [CI] 2.788–59.749), and in particular, ICP ≥ 15 mm Hg within 6 h of BCT was associated with poor neurological outcome (adjusted odds ratio 9.36, 95% CI 1.664–52.614). Therefore, early-controlled ICP after BCT was associated with clinical prognosis. There were no significant differences in the complications associated with BCT between the two neurological outcome groups. No BCT-induced death was observed. The active and timely control of RICH may be beneficial for clinical outcomes in patients with RICH after brain tumor surgery.

Mesenchymal stem cell therapies in brain disease

As treatments for diseases throughout the body progress, treatment for many brain diseases has been at a standstill due to difficulties in drug delivery. While new drugs are being discovered in vitro, these therapies are often hindered by inefficient tissue distribution and, more commonly, an inability to cross the blood brain barrier. Mesenchymal stem cells are thus being investigated as a delivery tool to directly target therapies to the brain to treat wide array of brain diseases. This review discusses the use of mesenchymal stem cells in hypoxic disease (hypoxic ischemic encephalopathy), an inflammatory neurodegenerative disease (multiple sclerosis), and a malignant condition (glioma).

Acute Management of Hypertension Following Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is responsible for approximately 15% of strokes annually in the United States, with nearly 1 in 3 of these patients dying without ever leaving the hospital. Because this disproportionate mortality risk has been stagnant for nearly 3 decades, a main area of research has been focused on the optimal strategies to reduce mortality and improve functional outcomes. The acute hypertensive response following ICH has been shown to facilitate ICH expansion and is a strong predictor of mortality. Rapidly reducing blood pressure was once thought to induce cerebral ischemia, though has been found to be safe in certain patient populations. Clinicians must work quickly to determine whether specific patient populations may benefit from acute lowering of systolic blood pressure (SBP) following ICH. This review provides nurses with a summary of the available literature on blood pressure control following ICH. It focuses on intravenous and oral antihypertensive medications available in the United States that may be utilized to acutely lower SBP, as well as medications outside of the antihypertensive class used during the acute setting that may reduce SBP.

Current trends in the management of canine traumatic brain injury: An Internet-based survey

This study characterized trends in management of canine traumatic brain injury (TBI) among 182 small animal veterinarians grouped as follows: Board-certified specialists at a veterinary teaching hospital (BCS-VTH), Board-certified specialists in private practice (BCS-PP), non-specialists at a teaching hospital (DVM-VTH), and non-specialists in private practice (DVM-PP). The BCS-VTH, BSC-PP, and DVM-VTH groups were more comfortable using the modified Glasgow Coma Scale (MGCS) than the DVM-PP group (P < 0.001, P < 0.001, and P = 0.009, respectively). All respondents chose the following diagnostics most frequently: packed cell volume/total solids (95.6%), blood glucose (96.7%), and blood pressure (95.0%). The DVM-VTH group chose the following more frequently than the DVM-PP group: computed tomography (19.4% versus 4.5%; P = 0.027), venous or arterial blood gas (83.9% versus 46.3%; P < 0.001), electrocardiography (71.0% versus 44.8%; P = 0.018), lactate (87.1% versus 59.7%; P = 0.009), and brief thoracic ultrasound (87.1% versus 62.7%; P = 0.017). BCS-PP chose hypertonic saline more frequently than DVM-PP (94.1% versus 74.6%; P = 0.005). The DVM-PP group chose corticosteroid therapy and anticonvulsant therapy more frequently than BCS-PP (10.4% versus 0.0%; P = 0.019; 73.1% versus 43.1%; P = 0.004, respectively). This study highlights variability in management of canine TBI.

Systolic blood pressure lower than the heart rate indicates a poor outcome in patients with severe isolated traumatic brain injury: A cross-sectional study

BACKGROUND

A systolic blood pressure (SBP) lower than the heart rate (HR) could indicate a poor condition in trauma patients. In such scenarios, the reversed shock index (RSI) is < 1, as calculated by the SBP divided by the HR. This study aimed to clarify whether RSI could be used to identify high-risk adult patients with isolated traumatic brain injury (TBI).

METHODS

This retrospective study reviewed 1216 hospitalized adult patients with isolated TBI at a Level I trauma center between January 1, 2009 and December 31, 2015. The patients were grouped and analyzed according to RSI (<1 or ≥ 1). Subgroups of patients with severe TBI (Glasgow Coma Scale [GCS] ≤ 8) or non-severe TBI (GCS > 8) were also compared. The primary outcome was in-hospital mortality. The odds ratios (ORs) of categorical variables were calculated by chi-square tests with 95% confidence intervals (CIs). Mann-Whitney U-tests were used to analyze non-normally distributed continuous data.

RESULTS

Among patients with isolated TBI, those with an RSI <1 had higher mortality (44.7% vs. 7.1%, OR: 10.5, 95% CI: 5.36-20.75; P < 0.001) than those with an RSI ≥1. An RSI <1 indicated a higher risk of mortality (OR: 5.1, 95% CI: 2.08-12.49; P < 0.001) in patients with severe isolated TBI but not in patients with non-severe isolated TBI (OR: 3.6, 95% CI: 0.45-28.71; P = 0.267).

CONCLUSION

Patients with isolated TBI may be at risk for shock. In trauma patients with severe isolated TBI, an SBP lower than the HR indicates a poor outcome.

Management Strategies for Intracranial Pressure Crises in Subarachnoid Hemorrhage

Objectives: Standard management strategies for lowering intracranial pressure (ICP) in traumatic brain injury has been well-studied, but the use of lesser known interventions for ICP in subarachnoid hemorrhage (SAH) remains elusive. Searches were performed in PubMed and EBSCO Host to identify best available evidence for evaluation and management of medically refractory ICP in SAH. The role of standard management strategies such as head elevation, hyperventilation, mannitol and hypertonic saline as well as lesser known management such as sodium bicarbonate, indomethacin, tromethamine, decompressive craniectomy, decompressive laparotomy, hypothermia, and barbiturate coma are reviewed. We also included dose concentrations, dose frequency, infusion volume, and infusion rate for these lesser known strategies. Nonetheless, there is still a gap in the evidence to recommend optimal dosing, timing and its role in the improvement of outcomes but early diagnosis and appropriate management reduce adverse outcomes.

Improvement of Color Vision Following Posterior Cranial Vault Distraction for Crouzon Syndrome

Crouzon syndrome (CS) is one of the craniosynostosis syndromes that leads to early fusion of cranial sutures and increased intracranial pressure. Intracranial hypertension is a serious complication that may lead to vision loss and cognitive impairment. Early detection and management are necessary to prevent complications. The authors present a patient with CS who underwent posterior cranial vault reconstruction with internal distraction after multiple episodes of headache and papilledema. The patient was unaware of any loss of color vision before the surgery; however, he noted an improvement in his color vision after the surgery. Color vision deficits may be an early sign of intracranial hypertension and finding these deficits using noninvasive testing methods may be an indication for early intervention.

Intracranial pressure influences the level of sympathetic tone

Sympathetic overdrive is associated with many diseases, but its origin remains an enigma. An emerging hypothesis in the development of cardiovascular disease is that the brain puts the utmost priority on maintaining its own blood supply; even if this comes at the "cost" of high blood pressure to the rest of the body. A critical step in making a causative link between reduced brain blood flow and cardiovascular disease is how changes in cerebral perfusion affect the sympathetic nervous system. A direct link between decreases in cerebral perfusion pressure and sympathetic tone generation in a conscious large animal has not been shown. We hypothesized that there is a novel control pathway between physiological levels of intracranial pressure (ICP) and blood pressure via the sympathetic nervous system. Intracerebroventricular infusion of saline produced a ramped increase in ICP of up to 20 mmHg over a 30-min infusion period (baseline 4.0 ± 1.1 mmHg). The ICP increase was matched by an increase in mean arterial pressure such that cerebral perfusion pressure remained constant. Direct recordings of renal sympathetic nerve activity indicated that sympathetic drive increased with increasing ICP. Ganglionic blockade, by hexamethonium, preventing sympathetic transmission, abolished the increase in arterial pressure in response to increased ICP and was associated with a significant decrease in cerebral perfusion pressure. This is the first study to show that physiological elevations in ICP regulate renal sympathetic activity in conscious animals. We have demonstrated a novel physiological mechanism linking ICP levels with sympathetic discharge via a possible novel intracranial baroreflex.

Identifying causal relationships between EEG activity and intracranial pressure changes in neurocritical care patients

OBJECTIVE

To explore and assess the relationship between electroencephalography (EEG) activity and intracranial pressure (ICP) in patients suffering from traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) during their stay in an intensive care unit.

APPROACH

We performed an observational prospective cohort study of adult patients suffering from TBI or SAH. Continuous EEG-ECG was performed during ICP monitoring. In every patient, variables derived from the EEG were calculated and the Granger causality (GC) methodology was employed to assess whether, and in which direction, there is any relationship between EEG and ICP.

MAIN RESULTS

One-thousand fifty-five hours of continuous multimodal monitoring were analyzed in 21 patients using the GC test. During 37.88% of the analyzed time, significant GC statistic was found in the direction from the EEG activity to the ICP, with typical lags of 25-50 s between them. When recordings were adjusted by sedation-perfusion and/or bolus-and handling, these percentages hardly changed.

SIGNIFICANCE

Long-lasting, continuous and simultaneous EEG and ICP recordings from TBI and SAH patients provide highly rich and useful information, which has allowed for uncovering a strong relationship between both signals. The use of this relationship could lead to developing a medical device to measure ICP in a non-invasive way.

Is bulk flow plausible in perivascular, paravascular and paravenous channels?

BACKGROUND

Transport of solutes has been observed in the spaces surrounding cerebral arteries and veins. Indeed, transport has been found in opposite directions in two different spaces around arteries. These findings have motivated hypotheses of bulk flow within these spaces. The glymphatic circulation hypothesis involves flow of cerebrospinal fluid from the cortical subarachnoid space to the parenchyma along the paraarterial (extramural, Virchow-Robin) space around arteries, and return flow to the cerebrospinal fluid (CSF) space via paravenous channels. The second hypothesis involves flow of interstitial fluid from the parenchyma to lymphatic vessels along basement membranes between arterial smooth muscle cells.

METHODS

This article evaluates the plausibility of steady, pressure-driven flow in these channels with one-dimensional branching models.

RESULTS

According to the models, the hydraulic resistance of arterial basement membranes is too large to accommodate estimated interstitial perfusion of the brain, unless the flow empties to lymphatic ducts after only several generations (still within the parenchyma). The estimated pressure drops required to drive paraarterial and paravenous flows of the same magnitude are not large, but paravenous flow back to the CSF space means that the total pressure difference driving both flows is limited to local pressure differences among the different CSF compartments, which are estimated to be small.

CONCLUSIONS

Periarterial flow and glymphatic circulation driven by steady pressure are both found to be implausible, given current estimates of anatomical and fluid dynamic parameters.

Multimodal management of severe herpes simplex virus encephalitis: A case report and literature review

BACKGROUND

Herpes simplex encephalitis (HSE) is the most frequent sporadic encephalitis in the world. In severe cases of HSE, the pathology usually progresses with an increase in intracranial pressure secondary to cerebral edema and/or hemorrhagic necrosis. Currently no high-power studies exist regarding the management of severe HSE and most of the papers reported in the literature are case reports. Decompressive craniectomy, effective in some cases of pharmaco-resistant intracranial hypertension (ICH) resulting from other causes, may be suggested in severe HSE, with several good results reported in the literature.

CASE DESCRIPTION

The case of a 26-year-old man with severe HSE and a subsequent ICH is reported. In dealing with an ICH rebellious to conservative treatment, it was decided to perform a right decompressive hemicraniectomy, associated with a right temporal polectomy. The postoperative evolution was satisfactory, with normal neuropsychological tests and a Glasgow Outcome Scale of 1.

CONCLUSION

Although herpes simplex encephalitis is sometimes devastatingly complicated by intracranial hypertension, its management lacks consensus and reliable data in the literature remains scarce. Surgical as well as conservative treatment, used together in a multimodal approach, may hold the key to a greater control of intracranial pressure, thus resulting in a better outcome. In this multimodal management, the window of opportunity where surgery may be considered is small, and must be discussed further and more precisely in future articles.

The course of intracranial pressure after antipyretic therapy in acute brain injury

BACKGROUND

The present study was performed to evaluate intracranial pressure (ICP) variations after antipyretic therapy and their relationship to ICP at baseline (ICPbas) in acute brain injury (ABI) patients.

METHODS

We completed a retrospective analysis on data derived from 2 previously published prospective observational studies. The first study involved 32 ABI patients and was performed to elucidate the cerebral and hemodynamic effects of intravenous (IV) paracetamol. The second study involved 30 ABI patients and was performed to investigate cerebral and hemodynamic effects of intramuscular IM diclofenac sodium (DCF). Overall patient population was divided into 2 groups: 1) Group A (G-A) when ICPbas was ≤ 15 mmHg and 2) Group B (G-B) when ICPbas was > 15 mmHg. The main objective was to evaluate if ICPbas affects the time course of ICP after antipyretics administration.

RESULTS

Data from 62 ABI patients were analyzed. We failed to observe a significant change in ICP after antipyretic treatment in the overall group of patients (P1 = 0.486). A significant difference, however, was found between the two groups (P2 < 0.001). We observed that in the G-A, ICP increased in response to antipyretic administration, whereas in the G-B, ICP decreased. These opposite responses are reflected in the statistically significant interaction (P3 < 0.001).

CONCLUSIONS

Variation in ICP after antipyretic therapy is influenced by ICPbas. Specifically, patients with ICPbas ≤ 15 mmHg showed a significant increase in ICP after antipyretic therapy, while a significant reduction in ICP was observed in patients with ICPbas > 15 mmHg.

Quantitative Phase-Contrast MR Angiography to Measure Hemodynamic Changes in Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE

Idiopathic intracranial hypertension is a syndrome of raised intracranial pressure of unknown etiology. Few MR imaging-based studies have investigated arterial and venous blood flow in these patients. Results are inconclusive, and to our knowledge, no comparison of the hemodynamic parameters before and after CSF pressure reduction has been published. The aim of this study was to assess the short-term effects of normalizing CSF pressure on intracranial flow to better understand the pathophysiology of idiopathic intracranial hypertension.

MATERIALS AND METHODS

In this study, we performed quantitative MR imaging-derived flow measurements of brain-supplying arteries and draining veins/dural sinuses to visualize hemodynamic changes in patients with idiopathic intracranial hypertension before and after therapy by lumbar puncture in comparison with a healthy control group.

RESULTS

We found differences in patients before and after lumbar puncture in the calculated resistance and pulsatility indices in the superior sagittal sinus. Venous pulsatility showed a negative correlation with CSF pressure in untreated patients. Additionally, there was a trend toward lower flow in the superior sagittal sinus in patients compared with healthy controls. Flow in the internal jugular veins was significantly reduced by lumbar puncture, and the resistance and pulsatility indices differed in patients and controls. The arterial flow was not influenced by pressure normalization.

CONCLUSIONS

The results of the present study indicate that venous but not arterial blood flow differs in patients compared with controls and that calculating resistance and pulsatility indices may contribute to assessing short-term hemodynamic changes in patients with diagnosed idiopathic intracranial hypertension before and after CSF diversion.

Cushing's sign and severe traumatic brain injury in children after blunt trauma: a nationwide retrospective cohort study in Japan

OBJECTIVE

We tested whether Cushing's sign could predict severe traumatic brain injury (TBI) requiring immediate neurosurgical intervention (BI-NSI) in children after blunt trauma.

DESIGN

Retrospective cohort study using Japan Trauma Data Bank.

SETTING

Emergency and critical care centres in secondary and tertiary hospitals in Japan.

PARTICIPANTS

Children between the ages of 2 and 15 years with Glasgow Coma Scale motor scores of 5 or less at presentation after blunt trauma from 2004 to 2015 were included. A total of 1480 paediatric patients were analysed.

PRIMARY OUTCOME MEASURES

Patients requiring neurosurgical intervention within 24 hours of hospital arrival and patients who died due to isolated severe TBI were defined as BI-NSI. The combination of systolic blood pressure (SBP) and heart rate (HR) on arrival, which were respectively divided into tertiles, and its correlation with BI-NSI were investigated using a multiple logistic regression model.

RESULTS

In the study cohort, 297 (20.1%) exhibited BI-NSI. After adjusting for sex, age category and with or without haemorrhage shock, groups with higher SBP and lower HR (SBP ≥135 mm Hg; HR ≤92 bpm) were significantly associated with BI-NSI (OR 2.84, 95% CI 1.68 to 4.80, P<0.001) compared with the patients with normal vital signs. In age-specific analysis, hypertension and bradycardia were significantly associated with BI-NSI in a group of 7-10 and 11-15 years of age; however, no significant association was observed in a group of 2-6 years of age.

CONCLUSIONS

Cushing's sign after blunt trauma was significantly associated with BI-NSI in school-age children and young adolescents.

Intracranial Pressure Is a Determinant of Sympathetic Activity

Intracranial pressure (ICP) is the pressure within the cranium. ICP rise compresses brain vessels and reduces cerebral blood delivery. Massive ICP rise leads to cerebral ischemia, but it is also known to produce hypertension, bradycardia and respiratory irregularities due to a sympatho-adrenal mechanism termed Cushing response. One still unresolved question is whether the Cushing response is a non-synaptic acute brainstem ischemic mechanism or part of a larger physiological reflex for arterial blood pressure control and homeostasis regulation. We hypothesize that changes in ICP modulates sympathetic activity. Thus, modest ICP increase and decrease were achieved in mice and patients with respectively intra-ventricular and lumbar fluid infusion. Sympathetic activity was gauged directly by microneurography, recording renal sympathetic nerve activity in mice and muscle sympathetic nerve activity in patients, and gauged indirectly in both species by heart-rate variability analysis. In mice (n = 15), renal sympathetic activity increased from 29.9 ± 4.0 bursts.s⁻¹ (baseline ICP 6.6 ± 0.7 mmHg) to 45.7 ± 6.4 bursts.s⁻¹ (plateau ICP 38.6 ± 1.0 mmHg) and decreased to 34.8 ± 5.6 bursts.s⁻¹ (post-infusion ICP 9.1 ± 0.8 mmHg). In patients (n = 10), muscle sympathetic activity increased from 51.2 ± 2.5 bursts.min⁻¹ (baseline ICP 8.3 ± 1.0 mmHg) to 66.7 ± 2.9 bursts.min⁻¹ (plateau ICP 25 ± 0.3 mmHg) and decreased to 58.8 ± 2.6 bursts.min⁻¹ (post-infusion ICP 14.8 ± 0.9 mmHg). In patients 7 mmHg ICP rise significantly increases sympathetic activity by 17%. Heart-rate variability analysis demonstrated a significant vagal withdrawal during the ICP rise, in accordance with the microneurography findings. Mice and human results are alike. We demonstrate in animal and human that ICP is a reversible determinant of efferent sympathetic outflow, even at relatively low ICP levels. ICP is a biophysical stress related to the forces within the brain. But ICP has also to be considered as a physiological stressor, driving sympathetic activity. The results suggest a novel physiological ICP-mediated sympathetic modulation circuit and the existence of a possible intracranial (i.e., central) baroreflex. Modest ICP rise might participate to the pathophysiology of cardio-metabolic homeostasis imbalance with sympathetic over-activity, and to the pathogenesis of sympathetically-driven diseases.

Stress testing of electrically active FlexMEAs with simultaneous electrical recording in fluidic environment: Introduction of a new measurement setup

We present a measurement setup consisting of two fluid-filled pressure chambers to mimic the mechanical stress likely to that of small body movements on biomedical flexible micro-electrode arrays for the analysis of various degradation mechanisms. Our main goal was the simulation of micro-motions in fluid conditions, while maintaining an electric access to the device. These micro-motions would be likely to those occurring in the human body caused by the intracranial pressure in magnitudes of 7-25 mmHg, which translates to a fluid pressure of 9-33 mbar. Furthermore, severe mechanical stress can be administered to the samples under the previously mentioned environment. Therefore, a flexible, polyimide-based sample with various metal test structures was fabricated and analyzed in the presented measurement setup. A comparison of the elongation of the sample's surface as a function of the applied hydrostatic pressure is given with computer simulations.

Methods of Mesenchymal Stem Cell Homing to the Blood-Brain Barrier

Mesenchymal stem/stromal cells (MSC) are multipotent cells that can be isolated from adult and fetal tissues. In vitro, MSCs show functional plasticity by differentiating into specialized cells of all germ layers. MSCs are of relevant to medicine and have been proposed for several disorders. MSCs can be transplanted across allogeneic barriers as "off the shelf" cells. This chapter focuses on methods to deliver MSCs to the brain because neurological pathology such as damage due to stroke can lead to debilitating mental and physical problems. In general, neurological diseases are difficult to treat, partly due to the challenge in getting drugs across the blood-brain barrier (BBB). MSCs as well as other stem cells can cross the BBB. The described method begins to develop procedures, leading to efficient delivery of drugs to the brain. Here describe how MSCs can be propagated from bone marrow aspirates and their utility in delivering small RNA to the brain. The chapter discusses the issue to enhance efficient delivery of MSCs to the brain.

Impacts of Simulated Weightlessness by Dry Immersion on Optic Nerve Sheath Diameter and Cerebral Autoregulation

Dry immersion (DI) is used to simulate weightlessness. We investigated in healthy volunteers if DI induces changes in ONSD, as a surrogate marker of intracranial pressure (ICP) and how these changes could affect cerebral autoregulation (CA). Changes in ICP were indirectly measured by changes in optic nerve sheath diameter (ONSD). 12 healthy male volunteers underwent 3 days of DI. ONSD was indirectly assessed by ocular ultrasonography. Cerebral blood flow velocity (CBFV) of the middle cerebral artery was gauged using transcranial Doppler ultrasonography. CA was evaluated by two methods: (1) transfer function analysis was calculated to determine the relationship between mean CBFV and mean arterial blood pressure (ABP) and (2) correlation index Mxa between mean CBFV and mean ABP.ONSD increased significantly during the first day, the third day and the first day of recovery of DI (P < 0.001).DI induced a reduction in Mxa index (P < 0.001) and an elevation in phase shift in low frequency bandwidth (P < 0.05). After DI, Mxa and coherence were strongly correlated with ONSD (P < 0.05) but not before DI. These results indicate that 3 days of DI induces significant changes in ONSD most likely reflecting an increase in ICP. CA was improved but also negatively correlated with ONSD suggesting that a persistent elevation ICP favors poor CA recovery after simulated microgravity.