Noninvasive Neuromonitoring: Current Utility in Subarachnoid Hemorrhage, Traumatic Brain Injury, and Stroke

Multimodal monitoring in patients with acute brain injury - A survey from critical care providers

BACKGROUND

Multimodal neuromonitoring (MMM) aims to improve outcome after acute brain injury, and thus admission in specialized Neurocritical Care Units with potential access to MMM is necessary. Various invasive and noninvasive modalities have been developed, however there is no strong evidence to support monitor combinations nor is there a known standardized approach. The goal of this study is to identify the most used invasive and non-invasive neuromonitoring modalities in daily practice as well as ubiquitousness of MMM standardization.

METHODS

In order to investigate current availability and protocolized implementation of MMM among neurocritical care units in US and non-US intensive care units, we designed a cross-sectional survey consisting of a self-administered online questionnaire of 20 closed-ended questions disseminated by the Neurocritical Care Society.

RESULTS

Twenty-one critical care practitioners responded to our survey with a 76% completion rate. The most commonly utilized non-invasive neuromonitoring modalities were continuous electroencephalography followed by transcranial doppler. The most common invasive modalities were external ventricular drain followed by parenchymal intracranial pressure (ICP) monitoring. MMM is most utilized in patients with subarachnoid hemorrhage and there were no differences regarding established institutional protocol, 24-h cEEG availability and invasive monitor placement between teaching and non-teaching hospitals. MMM is considered standard of care in 28% of responders' hospitals, whereas in 26.7% it is deemed experimental and only done as part of clinical trials. Only 26.7% hospitals use a computerized data integration system.

CONCLUSION

Our survey revealed overall limited use of MMM with no established institutional protocols among institutions. Ongoing research and further standardization of MMM will clarify its benefit to patients suffering from severe brain injury.

The Role of Automated Infrared Pupillometry in Traumatic Brain Injury: A Narrative Review

Pupillometry, an integral component of neurological examination, serves to evaluate both pupil size and reactivity. The conventional manual assessment exhibits inherent limitations, thereby necessitating the development of portable automated infrared pupillometers (PAIPs). Leveraging infrared technology, these devices provide an objective assessment, proving valuable in the context of brain injury for the detection of neuro-worsening and the facilitation of patient monitoring. In cases of mild brain trauma particularly, traditional methods face constraints. Conversely, in severe brain trauma scenarios, PAIPs contribute to neuro-prognostication and non-invasive neuromonitoring. Parameters derived from PAIPs exhibit correlations with changes in intracranial pressure. It is important to acknowledge, however, that PAIPs cannot replace invasive intracranial pressure monitoring while their widespread adoption awaits robust support from clinical studies. Ongoing research endeavors delve into the role of PAIPs in managing critical neuro-worsening in brain trauma patients, underscoring the non-invasive monitoring advantages while emphasizing the imperative for further clinical validation. Future advancements in this domain encompass sophisticated pupillary assessment tools and the integration of smartphone applications, emblematic of a continually evolving landscape.

Invasive Neuromonitoring in the Stroke Patient

With advances in technology, the options to manage patients with neurologic injuries are often complex. Critical care management of neurologic injury has historically focused on the prevention of secondary ischemic injury through aggressive management of intracranial pressure (ICP) and maintenance of adequate cerebral perfusion pressure (CPP). However, ICP monitoring alone does not identify ischemic changes that herald patient deterioration. Advocates of multimodality monitoring cite the value of early detection of changes in brain oxygenation levels and brain metabolism as advantageous in optimizing stroke outcomes. ICP monitoring alone should not be the sole source of information on which therapy is guided but should be incorporated into the arsenal of emerging and promising invasive neuromonitoring devices.

Cerebral hemodynamic changes to transcranial Doppler sonography in celiac disease: A pilot study

Background

Sonographic mesenteric pattern in celiac disease (CD) suggests a hyperdynamic circulation. Despite the well-known CD-related neurological involvement, no study has systematically explored the cerebral hemodynamics to transcranial Doppler sonography.

Materials and methods

Montreal Cognitive Assessment (MoCA) and 17-item Hamilton Depression Rating Scale (HDRS) were assessed in 15 newly diagnosed subjects with CD and 15 age-, sex-, and education-matched healthy controls. Cerebral blood flow (CBF) velocities and indices of resistivity (RI) and pulsatility (PI) from the middle cerebral artery (MCA), bilaterally, and the basilar artery (BA) were recorded. We also assessed cerebral vasomotor reactivity (CVR) through the breath-holding test (BHT).

Results

Worse scores of MoCA and HDRS were found in patients compared to controls. Although patients showed higher values of CBF velocity from MCA bilaterally compared to controls, both at rest and after BHT, no comparison reached a statistical significance, whereas after BHT both RI and PI from BA were significantly higher in patients. A significant negative correlation between both indices from BA and MoCA score were also noted.

Conclusion

These treatment-naïve CD patients may show some subtle CVR changes in posterior circulation, thus possibly expanding the spectrum of pathomechanisms underlying neuroceliac disease and in particular gluten ataxia. Subclinical identification of cerebrovascular pathology in CD may help adequate prevention and early management of neurological involvement.

Pathogenesis and research progress in leukoaraiosis

Leukoaraiosis is a common imaging marker of cerebral small vessel disease. In recent years, with the continuous advances in brain imaging technology, the detection rate of leukoaraiosis is higher and its clinical subtypes are gradually gaining attention. Although leukoaraiosis has long been considered an incidental finding with no therapeutic necessity, there is now growing evidence linking it to, among other things, cognitive impairment and a high risk of death after stroke. Due to different research methods, some of the findings are inconsistent and even contradictory. Therefore, a comprehensive and in-depth study of risk factors for leukoaraiosis is of great clinical significance. In this review, we summarize the literature on leukoaraiosis in recent years with the aim of elucidating the disease in terms of various aspects (including pathogenesis, imaging features, and clinical features, etc.).

Ten Rules for the Management of Moderate and Severe Traumatic Brain Injury During Pregnancy: An Expert Viewpoint

Moderate and severe traumatic brain injury (TBI) are major causes of disability and death. In addition, when TBI occurs during pregnancy, it can lead to miscarriage, premature birth, and maternal/fetal death, engendering clinical and ethical issues. Several recommendations have been proposed for the management of TBI patients; however, none of these have been specifically applied to pregnant women, which often have been excluded from major trials. Therefore, at present, evidence on TBI management in pregnant women is limited and mostly based on clinical experience. The aim of this manuscript is to provide the clinicians with practical suggestions, based on 10 rules, for the management of moderate to severe TBI during pregnancy. In particular, we firstly describe the pathophysiological changes occurring during pregnancy; then we explore the main strategies for the diagnosis of TBI taking in consideration the risks related to mother and fetus, and finally we discuss the most appropriate approaches for the management in this particular condition. Based on the available evidence, we suggest a stepwise approach consisting of different tiers of treatment and we describe the specific risks according to the severity of the neurological and systemic conditions of both fetus and mother in relation to each trimester of pregnancy. The innovative feature of this approach is the fact that it focuses on the vulnerability and specificity of this population, without forgetting the current knowledge on adult non-pregnant patients, which has to be applied to improve the quality of the care process.

Waveform Morphology as a Surrogate for ICP Monitoring: A Comparison Between an Invasive and a Noninvasive Method

BACKGROUND

Although the placement of an intraventricular catheter remains the gold standard technique for measuring intracranial pressure (ICP), the method has several limitations. Therefore, noninvasive alternatives to ICP (ICPni) measurement are of great interest. The main objective of this study was to compare the correlation and agreement of wave morphology between ICP (standard intraventricular ICP monitoring) and a new ICPni monitor in patients admitted with stroke. The second objective was to estimate the discrimination of the noninvasive method to detect intracranial hypertension.

METHODS

We prospectively collected data of adults admitted to an intensive care unit with subarachnoid hemorrhage, intracerebral hemorrhage, or ischemic stroke in whom an invasive ICP monitor was placed. Measurements were simultaneously collected from two parameters [time-to-peak (TTP) and the ratio regarding the second and first peak of the ICP wave (P2/P1 ratio)] of ICP and ICPni wave morphology monitors (Brain4care). Intracranial hypertension was defined as an invasively measured sustained ICP > 20 mm Hg for at least 5 min.

RESULTS

We studied 18 patients (subarachnoid hemorrhage = 14; intracerebral hemorrhage = 3; ischemic stroke = 1) on 60 occasions with a median age of 52 ± 14.3 years. A total of 197,400 waves (2495 min) from both ICP (standard ICP monitoring) and the ICPni monitor were sliced into 1-min-long segments, and we determined TTP and the P2/P1 ratio from the mean pulse. The median invasively measured ICP was 13 (9.8-16.2) mm Hg, and intracranial hypertension was present on 18 occasions (30%). The correlation and agreement between invasive and noninvasive methods for wave morphology were strong for the P2/P1 ratio and moderate for TTP using categoric (κ agreement 88.1% and 71.3%, respectively) and continuous (intraclass correlation coefficient 0.831 and 0.584, respectively) measures. There was a moderate but significant correlation with the mean ICP value (P2/P1 ratio r = 0.427; TTP r = 0.353; p < 0.001 for all) between noninvasive and invasive techniques. The areas under the curve to estimate intracranial hypertension were 0.786 [95% confidence interval (CI) 0.72-0.93] for the P2/P1 ratio and 0.694 (95% CI 0.60-0.74) for TTP.

CONCLUSIONS

The new ICPni wave morphology monitor showed a good agreement with the standard invasive method and an acceptable discriminatory power to detect intracranial hypertension. Clinical trial registration Trial registration: NCT05121155.

Neurophysiological Examinations as Adjunctive Tool to Imaging Techniques in Spontaneous Intracerebral Hemorrhage: IRONHEART Study

Introduction: Intracerebral hemorrhage (ICH) is a devastating disease, which may lead to severe disability or even death. Although many factors may influence the outcome, neurophysiological examinations might also play a role in its course. Our aim was to examine whether the findings of electroencephalography (EEG) and transcranial magnetic stimulation (TMS) can predict the prognosis of these patients.

Methods: Between June 1 2017 and June 15 2021, 116 consecutive patients with ICH were enrolled prospectively in our observational study. Clinical examinations and non-Contrast computed tomography (NCCT) scan were done on admission for ICH; follow-up NCCT scans were taken at 14 ± 2 days and at 3 months ± 7 days after stroke onset. EEG and TMS examinations were also carried out.

Results: Of the patients in the study, 65.5% were male, and the mean age of the study population was 70 years. Most patients had a history of hypertension, 50.8% of whom had been untreated. In almost 20% of the cases, excessive hypertension was measured on admission, accompanied with >10 mmol/L blood glucose level, whereas their Glasgow Coma Scale was 12 on average. Presence of blood in the ventricles or subarachnoid space and high blood and perihematomal volumes meant poor prognosis. Pathological EEG was prognostic of a worse outcome. With TMS examination at 14 days, it might be possible to estimate outcome in a univariate model and the absence, or reduction of the amplitude of the motor evoked potentials was associated with poor prognosis.

Conclusion: Together with the clinical symptoms, the volume of bleeding, perihematomal edema (or their combined volume), and neurophysiological examinations like EEG and TMS play an important role in the neurological outcome of patients with ICH. This might affect the patients' rehabilitation plans in the future, since with the help of the examinations the subset of patients with potential for recovery could be identified.

The Role of Ultrasound as a Diagnostic and Therapeutic Tool in Experimental Animal Models of Stroke: A Review

Ultrasound is a noninvasive technique that provides real-time imaging with excellent resolution, and several studies demonstrated the potential of ultrasound in acute ischemic stroke monitoring. However, only a few studies were performed using animal models, of which many showed ultrasound to be a safe and effective tool also in therapeutic applications. The full potential of ultrasound application in experimental stroke is yet to be explored to further determine the limitations of this technique and to ensure the accuracy of translational research. This review covers the current status of ultrasound applied to monitoring and treatment in experimental animal models of stroke and examines the safety, limitations, and future perspectives.

Separation of normal and impaired dynamic cerebral autoregulation using deep embedded clustering: a proof-of-concept study

Objective. A previous study has shown that a data-driven approach can significantly improve the discriminative power of transfer function analysis (TFA) used to differentiate between normal and impaired cerebral autoregulation (CA) in two groups of data. The data was collected from both healthy subjects (assumed to have normal CA) and symptomatic patients with severe stenosis (assumed to have impaired CA). However, the sample size of the labeled data was relatively small, owing to the difficulty in data collection. Therefore, in this proof-of-concept study, we investigate the feasibility of using an unsupervised learning model to differentiate between normal and impaired CA on TFA variables without requiring labeled data for learning.Approach. Continuous arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV), which were recorded simultaneously for approximately 10 min, were included from 148 subjects (41 healthy subjects, 31 with mild stenosis, 13 with moderate stenosis, 22 asymptomatic patients with severe stenosis, and 41 symptomatic patients with severe stenosis). Tiecks' model was used to generate surrogate data with normal and impaired CA. A recently proposed unsupervised learning model was optimized and applied to separate the normal and impaired CA for both the surrogate data and real data.Main results. It achieved 98.9% and 74.1% accuracy for the surrogate and real data, respectively.Significance. To our knowledge, this is the first attempt to employ an unsupervised data-driven approach to assess CA using TFA. This method enables the development of a classifier to determine the status of CA, which is currently lacking.

Case Studies in Neuroscience: Transcranial Doppler assessment of increased cerebral blood flow during iterative seizures

This case study aimed at monitoring ictal vasodilation in a clinical setting to confirm the experimental data on enhanced cerebral perfusion during epileptic seizures. Clinical observation of a patient presenting relapsing seizures in the intensive care unit. Transcranial Doppler (TCD) was used to monitor both blood velocities and the arterial caliber in the B-flow mode as a proxy of blood flow of the middle cerebral artery (MCA). A 35-yr-old woman experienced partial epileptic seizures lasting for 1 min that recurred every 5 min. Seizures were monitored with continuous EEG and TCD. During the seizure, the MCA caliber increased whereas velocities remained stable, which doubled the MCA blood flow. Immediately after the seizure, the artery caliber returned to its initial value, and the velocities increased by one-third of the initial value. After intensification of antiepileptic treatment, clinical seizures ceased, and TCD findings returned to normal MCA caliber and velocities. Autoimmune encephalitis was identified by brain biopsy and the patient recovered with corticosteroids treatment. This is the first description of ictal vasodilatation assessed by TCD. Our current understanding holds that cerebral blood flow increases during a seizure, but our report demonstrates that arterial dilation preceded the acceleration of velocities. This case study in a clinical setting confirms the impact of seizures on cerebral blood flow. NEW & NOTEWORTHY The case study is a clinical demonstration of ictal vasodilation. By assessing arterial caliber and blood velocities with transcranial Doppler, we dissected the impact of seizures on blood flow of the middle cerebral artery in the following sequence: 1) vasodilation occurred, concomitant to the epileptic activity, whereas the blood velocities remained stable and 2) immediately after the seizure, the velocities increased and the artery caliber returned to its initial value. As per author, there was no protocol, but one patient gave consent to use data from her medical file.

Paradoxical Contralateral Herniation Detected by Pupillometry in Acute Syndrome of the Trephined

Severe traumatic brain injury has historically been a non-survivable injury. Recent advances in neurosurgical care, however, have demonstrated that these patients not only can survive, but they also can recover functionally when they undergo appropriate cerebral decompression within hours of injury. At the present, general surgeons are deployed further forward than neurosurgeons (Role 2 compared to Role 3) and have been provided with guidelines that stipulate conditions where they may have to perform decompressive craniectomies. Unfortunately, Role 2 medical facilities do not have access to computed tomography imaging or intracranial pressure monitoring capabilities rendering the decision to proceed with craniectomy based solely on exam findings. Utilizing a case transferred from downrange to our institution, we demonstrate the utility of a small, highly portable quantitative pupillometer to obtain reliable and reproducible data about a patient's intracranial pressures. Following the case presentation, the literature supporting quantitative pupillometry for surgical decision-making is reviewed.

Prognostic Value of Various Hemostasis Parameters and Neurophysiological Examinations in Spontaneous Intracerebral Hemorrhage: The IRONHEART Study Protocol

Rationale: Stroke is one of the leading causes of death in all developed countries. In Hungary, more than 10,000 patients die annually due to cerebrovascular diseases according to the WHO Mortality Database. Of these patients, 10–15 % suffer non-traumatic intracerebral hemorrhage (ICH). ICH results in a higher rate of mortality as compared to ischemic stroke and outcomes are difficult to predict. In the IRONHEART study, we aim to test various hemostasis parameters and clinical neurophysiological examinations in evaluating outcome in ICH.

Methods: In this prospective, observational study, we plan to enroll consecutive patients with non-traumatic spontaneous ICH admitted to a single Stroke Center (Department of Neurology, University of Debrecen, Hungary). The protocol of the IRONHEART study includes the investigation of detailed clinical, laboratory investigations, and various neurophysiological examinations. Stroke severity is quantified based on the National Institutes of Health Stroke Scale (NIHSS) on admission and day 7, 14, and 90 after the onset of stroke. Cranial CT is performed on admission, day 14, and 90 to estimate the ICH volume. Modified Rankin Scale (mRS) is used for evaluating the long-term outcome (90 days post-event). Blood is drawn immediately on admission for specific hemostasis tests. Digital and quantitative EEG techniques and motor evoked potential (MEP) are performed to evaluate the prognosis of cerebral hemorrhage on admission (within 24–48 h), immediately before discharge (~10–14 days later), and 3 months after the event.

Outcomes: The following outcomes are investigated: primary outcomes: mortality by day 14 and day 90, secondary long-term outcome at 90 days post-event where mRS 0–2 is defined as favorable long-term outcome.

Discussion: If associations between outcomes and the investigated parameters (hemostasis and neurophysiological examinations) are confirmed, results might aid prognosis assessment in this subtype of stroke with particularly high mortality. Improving clinical grading systems on ICH severity and outcomes by including the investigated parameters could help to better guide the management of these patients in the future.

Near-Infrared Spectroscopy (NIRS) in Traumatic Brain Injury (TBI)

Traumatic brain injury (TBI) occurs when a sudden trauma causes damage to the brain. TBI can result when the head suddenly and violently impacts an object or when an object pierces the skull and enters brain tissue. Secondary injuries after traumatic brain injury (TBI) can lead to impairments on cerebral oxygenation and autoregulation. Considering that secondary brain injuries often take place within the first hours after the trauma, noninvasive monitoring might be helpful in providing early information on the brain's condition. Near-infrared spectroscopy (NIRS) is an emerging noninvasive monitoring modality based on chromophore absorption of infrared light with the capability of monitoring perfusion of the brain. This review investigates the main applications of NIRS in TBI monitoring and presents a thorough revision of those applications on oxygenation and autoregulation monitoring. Databases such as PubMed, EMBASE, Web of Science, Scopus, and Cochrane library were utilized in identifying 72 publications spanning between 1977 and 2020 which were directly relevant to this review. The majority of the evidence found used NIRS for diagnosis applications, especially in oxygenation and autoregulation monitoring (59%). It was not surprising that nearly all the patients were male adults with severe trauma who were monitored mostly with continue wave NIRS or spatially resolved spectroscopy NIRS and an invasive monitoring device. In general, a high proportion of the assessed papers have concluded that NIRS could be a potential noninvasive technique for assessing TBI, despite the various methodological and technological limitations of NIRS.

Transcranial Doppler for Early Prediction of Cognitive Impairment after Aneurysmal Subarachnoid Hemorrhage and the Associated Clinical Biomarkers

Methods

Prospective study included 40 cases with acute aSAH. Initial evaluation by Glasgow Coma Scale (GCS) and the severity of aSAH was detected by both the clinical Hunt and Hess and radiological Fisher's grading scales. TCD was done for all patients five times within 10 days measuring the mean flow velocities (MFVs) of cerebral arteries. At the 3-month follow-up, patients were classified into two groups according to Montreal Cognitive Assessment (MoCA) scale: the first group was 31 cases (77.5%) with intact cognitive functions and the other group was 9 cases (22.5%) with impaired cognition.

Results

Patients with impaired cognitive functions showed significantly lower mean GCS (p = 0.03), significantly higher mean Hunt and Hess scale grades (p = 0.04), significantly higher mean diabetes mellitus (DM) (p = 0.03), significantly higher mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) (p = 0.02 and p = 0.005, respectively), and significantly higher MFVs measured within the first 10 days. The patients with cognitive impairment were accompanied by a higher incidence of hydrocephalus (p = 0.01) and a higher incidence of delayed cerebral ischemia (DCI) (p < 0.001). Logistic regression analysis detected that MFV ≥ 86  cm/s in the middle cerebral artery (MCA), MFV ≥ 68  cm/s in the anterior cerebral artery (ACA), and MFV ≥ 45  cm/s in the posterior cerebral artery (PCA) were significantly associated with increased risk of cognitive impairment.

Conclusion

Cognitive impairment after the 3-month follow-up phase in aSAH patients was 22.5%. Acute hydrocephalus and DCI are highly associated with poor cognitive function in aSAH. Increased MFV is a strong predictor for poor cognitive function in aSAH. This trial is registered with NCT04329208.

Quantitative Infrared Pupillometry in Nonconvulsive Status Epilepticus

BACKGROUND

Nonconvulsive status epilepticus (NCSE) is a frequent disorder in neurocritical care and diagnosing it can be challenging. NCSE patients often show altered pupil function, but nature and extent may vary. Infrared pupillometry allows detection of subtle changes of pupil function. The neurological pupil index (NPi) is considered a surrogate marker of global pupil function which is supposed to be independent of absolute parameters such as the pupil diameter.

OBJECTIVE

Cross-sectional observational study to assess whether NPi is altered in NCSE.

METHODS

128 consecutive adult emergency patients who had experienced a suspected seizure, have not reached their prior functional level regarding level of consciousness, mental status or focal deficits, had no obvious clinical signs of status epilepticus and had an EEG indication as determined by the treating clinician for exclusion of NCSE were examined by routine EEG and pupillometry. Exclusion criteria were ocular comorbidity (n = 21) and poor EEG quality (n = 4). Pupillometry was performed once directly before the beginning of EEG recording. NCSE diagnosis (no NCSE, possible NCSE and confirmed NCSE) was established according to Salzburg consensus criteria blinded to pupillometry results. Group comparison was performed for right NPi, left NPi, lowest NPi of both sides (minNPi) and the absolute difference of both sides (diffNPi) applying non-parametric testing. In post-hoc analysis, receiver operating characteristics (ROC) of NCSE diagnosis (combined confirmed NCSE and possible NCSE) were performed for minNPi and diffNPi.

RESULTS

From 103 patients included in the final analysis, 5 (4.9%) had confirmed NCSE, 7 (6.8%) had possible NCSE. Right NPi (p = 0.002), left NPi (p < 0.001) and minNPi (p < 0.001) were significantly lower in "confirmed NCSE" and "possible NCSE" compared to "no NCSE"; diffNPi was significantly higher in "confirmed NCSE" and "possible NCSE" compared to "no NCSE" (p < 0.001). There was no significant difference of minNPi and diffNPi between "confirmed NCSE" and "possible NCSE". ROC analysis showed an optimal cut-off of minNPi for NCSE diagnosis of 4.0 (AUC = 0.93, 95% CI 0.86-0.99). Optimal ROC analysis cut-off of diffNPi for NCSE diagnosis was 0.2 (AUC = 0.89, 95% CI 0.80-0.99).

CONCLUSIONS

NPi was significantly reduced and the difference between left and right NPi was significantly higher in confirmed NCSE. An NPi < 4.0 on either side as well as an NPi difference of both sides > 0.2 may be potential indicators of NCSE. Infrared pupillometry may be a helpful diagnostic tool in the assessment of NCSE and should be studied further in larger populations.

A noninvasive flexible conformal sensor for accurate real-time monitoring of local cerebral edema based on electromagnetic induction

Cerebral edema (CE) is a non-specific pathological swelling of the brain secondary to any type of neurological injury. The real-time monitoring of focal CE mostly found in early stage is of great significance to reduce mortality and disability. Magnetic Induction Phase Shift (MIPS) is expected to achieve non-invasive continuous monitoring of CE. However, most existing MIPS sensors are made of hard materials which makes it difficult to accurately retrieve CE information. In this article, we designed a conformal two-coil structure and a single-coil structure, and studied their sensitivity map using finite element method (FEM). After that, the conformal MIPS sensor that is preferable for local CE monitoring was fabricated by flexible printed circuit (FPC). Next, physical experiments were conducted to investigate its performance on different levels of simulated CE solution volume, measurement distance, and bending. Subsequently, 14 rabbits were chosen to establish CE model and another three rabbits were selected as controls. The 24-hour MIPS real-time monitoring experiments was carried out to verify that the feasibility. Results showed a gentler attenuation trend of the conformal two-coil structure, compared with the single-coil structure. In addition, the novel flexible conformal MIPS sensor has a characteristic of being robust to bending according to the physical experiments. The results of animal experiments showed that the sensor can be used for CE monitoring. It can be concluded that this flexible conformal MIPS sensor is desirable for local focusing measurement of CE and subsequent multidimensional information extraction for predicting model. Also, it enables a much more comfortable environment for long-time bedside monitoring.

Sufentanil Reduces Emergence Delirium in Children Undergoing Transthoracic Device Closure of VSD After Sevoflurane-Based Cardiac Anesthesia

Objective

The aim of this study was to evaluate whether sufentanil can reduce emergence delirium in children undergoing transthoracic device closure of ventricular septal defect (VSD) after sevoflurane-based cardiac anesthesia.

Methods

From February 2019 to May 2019, 68 children who underwent transthoracic device closure of VSD at our center were retrospectively analyzed. All patients were divided into two groups: 36 patients in group S, who were given sufentanil and sevoflurane-based cardiac anesthesia, and 32 patients in group F, who were given fentanyl and sevoflurane-based cardiac anesthesia. The following clinical data were recorded: age, sex, body weight, operation time, and bispectral index (BIS). After the children were sent to the intensive care unit (ICU), pediatric anesthesia emergence delirium (PAED) and face, legs, activity, cry, consolability (FLACC) scale scores were also assessed. The incidence of adverse reactions, such as nausea, vomiting, drowsiness and dizziness, was recorded.

Results

There was no significant difference in age, sex, body weight, operation time or BIS value between the two groups. Extubation time (min), PEAD score and FLACC scale score in group S were significantly better than those in group F (P<0.05). No serious anesthesia or drug-related side effects occurred.

Conclusions

Sufentanil can be safely used in sevoflurane-based fast-track cardiac anesthesia for transthoracic device closure of VSD in children. Compared to fentanyl, sufentanil is more effective in reducing postoperative emergence delirium, with lower analgesia scores and greater comfort.

Cerebral Hemodynamic Changes to Transcranial Doppler in Asymptomatic Patients with Fabry's Disease

BACKGROUND

Patients with Fabry's disease (FD) may be asymptomatic or show a spectrum of clinical manifestations, including cerebrovascular disease, mainly affecting posterior circulation. Few and conflicting studies on cerebral blood flow (CBF) velocity by transcranial Doppler sonography (TCD) in asymptomatic FD (aFD) subjects have been published. Our study aims to assess TCD in aFD subjects to identify any preclinical CBF change.

METHODS

A total of 30 aFD subjects were consecutively recruited and compared to 28 healthy controls. Brain magnetic resonance imaging was normal in all participants. TCD was used to study blood flow velocity and indices of resistance of intracranial arteries from the middle cerebral artery (MCA), bilaterally, and from the basilar artery (BA). Cerebral vasomotor reactivity (CVR) was also evaluated from MCA.

RESULTS

No difference was found between groups for MCA parameters of CBF velocity and CVR. Compared to controls, a higher mean blood flow velocity and a lower resistance index from BA were observed in FD subjects. No correlation was found between any BA-derived TCD parameter and the level of lyso-globotriaosylceramide.

CONCLUSIONS

aFD subjects show evidence of altered CBF velocity in posterior circulation. Preclinical detection of neurovascular involvement in FD might allow appropriate management and prevention of future cerebrovascular complications and disability.

Cerebral Hemodynamic Changes to Transcranial Doppler in Asymptomatic Patients with Fabry's Disease

BACKGROUND

Patients with Fabry's disease (FD) may be asymptomatic or show a spectrum of clinical manifestations, including cerebrovascular disease, mainly affecting posterior circulation. Few and conflicting studies on cerebral blood flow (CBF) velocity by transcranial Doppler sonography (TCD) in asymptomatic FD (aFD) subjects have been published. Our study aims to assess TCD in aFD subjects to identify any preclinical CBF change.

METHODS

A total of 30 aFD subjects were consecutively recruited and compared to 28 healthy controls. Brain magnetic resonance imaging was normal in all participants. TCD was used to study blood flow velocity and indices of resistance of intracranial arteries from the middle cerebral artery (MCA), bilaterally, and from the basilar artery (BA). Cerebral vasomotor reactivity (CVR) was also evaluated from MCA.

RESULTS

No difference was found between groups for MCA parameters of CBF velocity and CVR. Compared to controls, a higher mean blood flow velocity and a lower resistance index from BA were observed in FD subjects. No correlation was found between any BA-derived TCD parameter and the level of lyso-globotriaosylceramide.

CONCLUSIONS

aFD subjects show evidence of altered CBF velocity in posterior circulation. Preclinical detection of neurovascular involvement in FD might allow appropriate management and prevention of future cerebrovascular complications and disability.

A Systematic Review Assessing the Current State of Automated Pupillometry in the NeuroICU

The aim of this study was to assess the current state of automated pupillometry technology and its application in the neurointensive care unit (neuroICU). We performed a literature search using the PubMed, MEDLINE, and EMBASE databases from database inception through a search end date of October 18, 2018, to identify studies reporting on the use of automated pupillometry in the care of critically ill patients with neurological impairment. Two independent reviewers reviewed all titles and abstracts in two filtering phases. Data were extracted independently. One hundred and forty-one articles/abstracts have been published on the use of automated pupillometry in critical care since inception of the PubMed, MEDLINE, and EMBASE databases. We selected and reviewed 22 full-text articles and 8 abstracts, of which 26 were prospective, 2 were retrospective, and 2 were larger case series. Automated pupillometry increased precision, reliability, and reproducibility compared with the manual pupillary examination; detected subtle and early pupillary changes; detected pupillary changes that indicate a rise, or impending rise, in intracranial pressure detected level of analgesia and depth of sedation; served as a prognostic indicator; estimated the clinical severity of aneurysmal subarachnoid hemorrhage; and served as a noninvasive monitor of response to osmotic therapy. At present, no consensus guidelines exist endorsing routine use of automated pupillometry in the neuroICU. However, an increasing quantity of research supports the usefulness of automated pupillometry in this setting. Further large-scale prospective studies are needed before updated consensus guidelines recommending widespread adoption of automated pupillometry are produced.

Resting-State NIRS-EEG in Unresponsive Patients with Acute Brain Injury: A Proof-of-Concept Study

BACKGROUND

Neurovascular-based imaging techniques such as functional MRI (fMRI) may reveal signs of consciousness in clinically unresponsive patients but are often subject to logistical challenges in the intensive care unit (ICU). Near-infrared spectroscopy (NIRS) is another neurovascular imaging technique but low cost, can be performed serially at the bedside, and may be combined with electroencephalography (EEG), which are important advantages compared to fMRI. Combined NIRS-EEG, however, has never been evaluated for the assessment of neurovascular coupling and consciousness in acute brain injury.

METHODS

We explored resting-state oscillations in eight-channel NIRS oxyhemoglobin and eight-channel EEG band-power signals to assess neurovascular coupling, the prerequisite for neurovascular-based imaging detection of consciousness, in patients with acute brain injury in the ICU (n = 9). Conscious neurological patients from step-down units and wards served as controls (n = 14). Unsupervised adaptive mixture-independent component analysis (AMICA) was used to correlate NIRS-EEG data with levels of consciousness and clinical outcome.

RESULTS

Neurovascular coupling between NIRS oxyhemoglobin (0.07-0.13 Hz) and EEG band-power (1-12 Hz) signals at frontal areas was sensitive and prognostic to changing consciousness levels. AMICA revealed a mixture of five models from EEG data, with the relative probabilities of these models reflecting levels of consciousness over multiple days, although the accuracy was less than 85%. However, when combined with two channels of bilateral frontal neurovascular coupling, weighted k-nearest neighbor classification of AMICA probabilities distinguished unresponsive patients from conscious controls with > 90% accuracy (positive predictive value 93%, false discovery rate 7%) and, additionally, identified patients who subsequently failed to recover consciousness with > 99% accuracy.

DISCUSSION

We suggest that NIRS-EEG for monitoring of acute brain injury in the ICU is worthy of further exploration. Normalization of neurovascular coupling may herald recovery of consciousness after acute brain injury.

Update on the Neurobiology of Vascular Cognitive Impairment: From Lab to Clinic

In the last years, there has been a significant growth in the literature exploring the pathophysiology of vascular cognitive impairment (VCI). As an "umbrella term" encompassing any degree of vascular-related cognitive decline, VCI is deemed to be the most common cognitive disorder in the elderly, with a significant impact on social and healthcare expenses. Interestingly, some of the molecular, biochemical, and electrophysiological abnormalities detected in VCI seem to correlate with disease process and progression, eventually promoting an adaptive plasticity in some patients and a maladaptive, dysfunctional response in others. However, the exact relationships between vascular lesion, cognition, and neuroplasticity are not completely understood. Recent findings point out also the possibility to identify a panel of markers able to predict cognitive deterioration in the so-called "brain at risk" for vascular or mixed dementia. This will be of pivotal importance when designing trials of disease-modifying drugs or non-pharmacological approaches, including non-invasive neuromodulatory techniques. Taken together, these advances could make VCI a potentially preventable cause of both vascular and degenerative dementia in late life. This review provides a timely update on the recent serological, cerebrospinal fluid, histopathological, imaging, and neurophysiological studies on this "cutting-edge" topic, including the limitations, future perspectives and translational implications in the diagnosis and management of VCI patients.

Update on the Neurobiology of Vascular Cognitive Impairment: From Lab to Clinic

In the last years, there has been a significant growth in the literature exploring the pathophysiology of vascular cognitive impairment (VCI). As an "umbrella term" encompassing any degree of vascular-related cognitive decline, VCI is deemed to be the most common cognitive disorder in the elderly, with a significant impact on social and healthcare expenses. Interestingly, some of the molecular, biochemical, and electrophysiological abnormalities detected in VCI seem to correlate with disease process and progression, eventually promoting an adaptive plasticity in some patients and a maladaptive, dysfunctional response in others. However, the exact relationships between vascular lesion, cognition, and neuroplasticity are not completely understood. Recent findings point out also the possibility to identify a panel of markers able to predict cognitive deterioration in the so-called "brain at risk" for vascular or mixed dementia. This will be of pivotal importance when designing trials of disease-modifying drugs or non-pharmacological approaches, including non-invasive neuromodulatory techniques. Taken together, these advances could make VCI a potentially preventable cause of both vascular and degenerative dementia in late life. This review provides a timely update on the recent serological, cerebrospinal fluid, histopathological, imaging, and neurophysiological studies on this "cutting-edge" topic, including the limitations, future perspectives and translational implications in the diagnosis and management of VCI patients.

Migrainous Infarction And Cerebral Vasospasm: Case Report And Literature Review

Migrainous infarction (MI) is a rare complication of migraines that accounts for 0.5-1.5% of all ischemic strokes. Although the pathogenesis of MI is still debated, cortical spreading depression and the consequent biochemical cascade and hemodynamic changes are presumed to play an important role. Here we describe a case of MI and systematically review the literature on the complex and possibly bidirectional relationship between migraine and stroke. A 44-year-old female with history of migraine with visual aura presented at the Emergency Department due to a sudden onset of left limb paresis and hypoesthesia. Brain magnetic resonance imaging revealed right fronto-parietal ischemic stroke. Two days after hospitalization, the patient experienced a prolonged visual aura and showed ultrasound evidence of intracranial artery vasospasm. To date, there have been 33 published articles on a total 119 patients with MI, although intracranial vasospasm has rarely been reported. Sustained hyperexcitability of cortical neurons, impairment of γ-aminobutyric acid inhibitory circuitry, altered serotonergic transmission, release of vasoconstrictive molecules, and cerebral blood flow changes have been proposed as pathogenic mechanisms of MI. The present case provides insight into the pathophysiological link between stroke and migraine, thus aiding clinicians in therapeutic decision-making although additional studies are needed to clarify the clinical, neuroradiological, and ultrasound findings that link MI and stroke-related migraine.

[Modern principles of neurocritical care]

Neurological diseases frequently demanding admittance to a dedicated neurological intensive care unit (neurocritical care) comprise space-occupying ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, traumatic brain injury, status epilepticus, bacterial meningitis, myasthenic crisis and Guillain-Barré syndrome. Due to often necessary analgesia, sedation and mechanical ventilation, neuromonitoring should ideally be employed. This consists of bedside invasive and non-invasive methods for monitoring cerebral perfusion, oxygenation, metabolism and neurophysiology. Modern treatment principles in neurocritical care mainly aim at avoiding or attenuating secondary neurological brain damage, in particular directed at sufficient perfusion and oxygenation. These include measures such as neuroprotective ventilation, stabilization of the circulation, decreasing intracranial pressure in brain edema and space-occupying processes, anticonvulsive treatment, temperature management and targeted disease-specific treatment.

Transcranial Doppler ultrasound in vascular cognitive impairment-no dementia

BACKGROUND

Although cerebral white matter lesions (WMLs) are considered as a risk factor for vascular dementia, data on their impact on cerebral hemodynamics are scarce. We test and compare transcranial Doppler (TCD) features in WML patients with or without associated cognitive impairment.

METHODS

A sample of non-demented elderly patients with WMLs was consecutively recruited. Mean blood flow velocity (MBFV), pulsatility index (PI), peak systolic blood flow velocity (PSV), end-diastolic blood flow velocity (EDV), and resistivity index (RI) were recorded from the middle cerebral artery bilaterally. Global cognitive functioning, frontal lobe abilities, functional status, and WML severity were also assessed.

RESULTS

161 patients satisfying the clinical criteria for vascular cognitive impairment-no dementia (VCI-ND) were age-matched with 97 presenting WMLs without any cognitive deficit. VCI-ND patients exhibited a decrease in MBFV and EDV, as well as an increase in PI, RI, and PSV. Moreover, a significant correlation between all TCD parameters and the severity of executive dysfunction was observed, whereas PI, RI, and EDV were significantly correlated with the WML load.

CONCLUSIONS

VCI-ND showed a hemodynamic pattern indicative of cerebral hypoperfusion and enhanced vascular resistance. These changes may be considered as the TCD correlate of VCI-ND due to microcirculation pathology. TCD provides useful indices of the occurrence and severity of small vessel disease and executive dysfunction in elderly patients at risk of future dementia.

Migrainous Infarction And Cerebral Vasospasm: Case Report And Literature Review

Migrainous infarction (MI) is a rare complication of migraines that accounts for 0.5-1.5% of all ischemic strokes. Although the pathogenesis of MI is still debated, cortical spreading depression and the consequent biochemical cascade and hemodynamic changes are presumed to play an important role. Here we describe a case of MI and systematically review the literature on the complex and possibly bidirectional relationship between migraine and stroke. A 44-year-old female with history of migraine with visual aura presented at the Emergency Department due to a sudden onset of left limb paresis and hypoesthesia. Brain magnetic resonance imaging revealed right fronto-parietal ischemic stroke. Two days after hospitalization, the patient experienced a prolonged visual aura and showed ultrasound evidence of intracranial artery vasospasm. To date, there have been 33 published articles on a total 119 patients with MI, although intracranial vasospasm has rarely been reported. Sustained hyperexcitability of cortical neurons, impairment of γ-aminobutyric acid inhibitory circuitry, altered serotonergic transmission, release of vasoconstrictive molecules, and cerebral blood flow changes have been proposed as pathogenic mechanisms of MI. The present case provides insight into the pathophysiological link between stroke and migraine, thus aiding clinicians in therapeutic decision-making although additional studies are needed to clarify the clinical, neuroradiological, and ultrasound findings that link MI and stroke-related migraine.

Transcranial Doppler ultrasound in vascular cognitive impairment-no dementia

BACKGROUND

Although cerebral white matter lesions (WMLs) are considered as a risk factor for vascular dementia, data on their impact on cerebral hemodynamics are scarce. We test and compare transcranial Doppler (TCD) features in WML patients with or without associated cognitive impairment.

METHODS

A sample of non-demented elderly patients with WMLs was consecutively recruited. Mean blood flow velocity (MBFV), pulsatility index (PI), peak systolic blood flow velocity (PSV), end-diastolic blood flow velocity (EDV), and resistivity index (RI) were recorded from the middle cerebral artery bilaterally. Global cognitive functioning, frontal lobe abilities, functional status, and WML severity were also assessed.

RESULTS

161 patients satisfying the clinical criteria for vascular cognitive impairment-no dementia (VCI-ND) were age-matched with 97 presenting WMLs without any cognitive deficit. VCI-ND patients exhibited a decrease in MBFV and EDV, as well as an increase in PI, RI, and PSV. Moreover, a significant correlation between all TCD parameters and the severity of executive dysfunction was observed, whereas PI, RI, and EDV were significantly correlated with the WML load.

CONCLUSIONS

VCI-ND showed a hemodynamic pattern indicative of cerebral hypoperfusion and enhanced vascular resistance. These changes may be considered as the TCD correlate of VCI-ND due to microcirculation pathology. TCD provides useful indices of the occurrence and severity of small vessel disease and executive dysfunction in elderly patients at risk of future dementia.