Myths and methodologies: Assessment of dynamic cerebral autoregulation by the mean flow index

The mean flow index-usually referred to as Mx-has been used for assessing dynamic cerebral autoregulation (dCA) for almost 30 years. However, concerns have arisen regarding methodological consistency, construct and criterion validity, and test-retest reliability. Methodological nuances, such as choice of input (cerebral perfusion pressure, invasive or non-invasive arterial pressure), pre-processing approach and artefact handling, significantly influence mean flow index values, and previous studies correlating mean flow index with other established dCA metrics are confounded by inherent methodological flaws like heteroscedasticity, while the mean flow index also fails to discriminate individuals with presumed intact versus impaired dCA (discriminatory validity), and its prognostic performance (predictive validity) across various conditions remains inconsistent. The test-retest reliability, both within and between days, is generally poor. At present, no single approach for data collection or pre-processing has proven superior for obtaining the mean flow index, and caution is advised in the further use of mean flow index-based measures for assessing dCA, as current evidence does not support their clinical application.

Comparable dynamic cerebral autoregulation and neurovascular coupling of the posterior cerebral artery between healthy men and women

AIMS

Most studies focus on dynamic cerebral autoregulation (dCA) in the middle cerebral artery (MCA), and few studies investigated neurovascular coupling (NVC) and dCA in the posterior cerebral artery (PCA). We investigated NVC and dCA of the PCA in healthy volunteers to identify sex differences.

METHODS

Thirty men and 30 age-matched women completed dCA and NCV assessments. The cerebral blood flow velocity (CBFV) and mean arterial pressure were evaluated using transcranial Doppler ultrasound and a servo-controlled plethysmograph, respectively. The dCA parameters were analyzed using transfer function analysis. The NCV was evaluated by eyes-open and eyes-closed (24 s each) periodically based on voice prompts. The eyes-open visual stimulation comprised silent reading of Beijing-related tourist information.

RESULTS

The PCA gain was lower than that of the MCA in all frequency ranges (all p < 0.05). Phase was consistent across the cerebrovascular territories. The cerebrovascular conductance index (CVCi) and mean CBFV (MV) of the PCA were significantly higher during the eyes-open than eyes-closed period (CVCi: 0.50 ± 0.12 vs. 0.38 ± 0.10; MV: 42.89 ± 8.49 vs. 32.98 ± 7.25, both p < 0.001). The PCA dCA and NVC were similar between the sexes.

CONCLUSION

We assessed two major mechanisms that maintain cerebral hemodynamic stability in healthy men and women. The visual stimulation-evoked CBFV of the PCA was significantly increased compared to that during rest, confirming the activation of NVC. Men and women have similar functions in PCA dCA and NCV.

Hyperemia in head injury: can transcranial doppler help to personalize therapies for intracranial hypertension?

Introduction

An increase in cerebral blood flow is frequent after traumatic brain injury (TBI) and can lead to brain swelling and refractory intracranial hypertension. We hypothesized that Transcranial EcoDoppler (TCD) monitoring could be useful to detect the cause of intracranial hypertension in these patients. Our main objective was to investigate if the increase of velocity in the middle cerebral artery (MCA) on TCD could be associated with intracranial hypertension.

Methods

We retrospectively studied TBI patients consecutively monitored with TCD. Hyperemia was defined as MCA mean velocity higher than 80 cm/s. Intracranial hypertension was considered when hyperosmolar therapy, hyperventilation, or deep sedation was used.

Results

We found hyperemia in 40 patients out of 118 (33.9%). On average, it started at day 2.1 ± 0.9 from admission and significantly increased (MCA velocity at day 1: 74 ± 25 cm/s vs. 109 ± 36 cm/s at day 4; p < 0.001). Intracranial hypertension was significantly associated with hyperemia, occurring in 92.5% of hyperemic and 51.3% of non-hyperemic patients (p < 0.001). Moreover, we found that hyperemia preceded severe intracranial hypertension (p < 0.0001). In a logistic regression model, hyperemia was the only variable significantly correlated with intracranial hypertension (OR 10.64; p < 0.001).

Discussion

Hyperemia was frequent in our population of TBI patients and preceded intracranial hypertension. TCD monitoring, if performed on a daily regular basis, can be a useful method to detect this phenomenon and to guide the therapy. It could be a tool for a cause-oriented therapy of intracranial hypertension.

Updates on Improving Imaging Modalities for Traumatic Brain Injury

The Center for Disease Control and Prevention reports that traumatic brain injury (TBI) was related to over 64,000 deaths in the United States in 2020, equating to more than 611 TBI-related hospitalizations and 176 TBI-related deaths per day. There are both long- and short-term sequelae involved with the pathophysiology of TBI that can range from mild to severe. Recently, more effort has been devoted to understanding the long-term consequences of TBI and how early detection of these injuries can prevent late clinical manifestations. Obtaining proper, detailed imaging is key to guiding the direction of intervention, but there is a gap in the understanding of how TBI imaging can be used to predict and prevent the long-term morbidities seen with even mild forms of TBI. There have been significant strides in the advancement of TBI imaging that allows for quicker, more affordable, and more effective imaging of intracranial bleeds, axonal injury, tissue damage, and more. Despite this, there is still room for improved standardization and more data supporting the justification of using certain imaging modalities. This review aims to outline recent advancements in TBI imaging and areas that require further investigation to improve patient outcomes and minimize the acute and chronic comorbidities associated with TBI.

The Use of Noninvasive Multimodal Neuromonitoring in Adult Critically Ill Patients With COVID-19 Infection

INTRODUCTION

Noninvasive neuromonitoring could be a valuable option for bedside assessment of cerebral dysfunction in patients with coronavirus disease-2019 (COVID-19) admitted to intensive care units (ICUs). This systematic review aims to investigate the use of noninvasive multimodal neuromonitoring in critically ill adult patients with COVID-19 infection.

METHODS

MEDLINE/PubMed, Scopus, Cochrane, and EMBASE databases were searched for studies investigating noninvasive neuromonitoring in patients with COVID-19 admitted to ICUs. The monitoring included transcranial Doppler ultrasonography (TCD), the Brain4care Corp. cerebral compliance monitor (B4C), optic nerve sheath diameter (ONSD), near infrared spectroscopy, automated pupillometry, and electroencephalography (EEG).

RESULTS

Thirty-two studies that investigated noninvasive neuromonitoring techniques in patients with COVID-19 in the ICU were identified from a systematic search of 7001 articles: 1 study investigating TCD, ONSD and pupillometry; 2 studies investigating the B4C device and TCD; 3 studies investigating near infrared spectroscopy and TCD; 4 studies investigating TCD; 1 case series investigating pupillometry, and 21 studies investigating EEG. One hundred and nineteen patients underwent TCD monitoring, 47 pupillometry, 49 ONSD assessment, 50 compliance monitoring with the B4C device, and 900 EEG monitoring. Alterations in cerebral hemodynamics, brain compliance, brain oxygenation, pupillary response, and brain electrophysiological activity were common in patients with COVID-19 admitted to the ICU; these abnormalities were not clearly associated with worse outcome or the development of new neurological complications.

CONCLUSIONS

The use of noninvasive multimodal neuromonitoring in critically ill COVID-19 patients could be considered to facilitate the detection of neurological derangements. Determining whether such findings allow earlier detection of neurological complications or guide appropriate therapy requires additional studies.

Thoracoabdominal normothermic regional perfusion in donation after circulatory death does not restore brain blood flow

Use of thoracoabdominal normothermic regional perfusion (TA-NRP) during donation after circulatory death (DCD) is an important advance in organ donation. Prior to establishing TA-NRP, the brachiocephalic, left carotid, and left subclavian arteries are ligated, thereby eliminating anterograde brain blood flow via the carotid and vertebral arteries. While theoretical concerns have been voiced that TA-NRP after DCD may restore brain blood flow via collaterals, there have been no studies to confirm or refute this possibility. We evaluated brain blood flow using intraoperative transcranial Doppler (TCD) in two DCD TA-NRP cases. Pre-extubation, anterior and posterior circulation brain blood flow waveforms were present in both cases, similar to the waveforms detected in a control patient on mechanical circulatory support undergoing cardiothoracic surgery. Following declaration of death and initiation of TA-NRP, no brain blood flow was detected in either case. Additionally, there was absence of brainstem reflexes, no response to noxious stimuli and no respiratory effort. These TCD results demonstrate that DCD with TA-NRP did not restore brain blood flow.

Intrapulmonary and Intracardiac Shunts in Adult COVID-19 Versus Non-COVID Acute Respiratory Distress Syndrome ICU Patients Using Echocardiography and Contrast Bubble Studies (COVID-Shunt Study): A Prospective, Observational Cohort Study

OBJECTIVES

Studies have suggested intrapulmonary shunts may contribute to hypoxemia in COVID-19 acute respiratory distress syndrome (ARDS) with worse associated outcomes. We evaluated the presence of right-to-left (R-L) shunts in COVID-19 and non-COVID ARDS patients using a comprehensive hypoxemia workup for shunt etiology and associations with mortality.

DESIGN

Prospective, observational cohort study.

SETTING

Four tertiary hospitals in Edmonton, Alberta, Canada.

PATIENTS

Adult critically ill, mechanically ventilated, ICU patients admitted with COVID-19 or non-COVID (November 16, 2020, to September 1, 2021).

INTERVENTIONS

Agitated-saline bubble studies with transthoracic echocardiography/transcranial Doppler ± transesophageal echocardiography assessed for R-L shunts presence.

MEASUREMENTS AND MAIN RESULTS

Primary outcomes were shunt frequency and association with hospital mortality. Logistic regression analysis was used for adjustment. The study enrolled 226 patients (182 COVID-19 vs 42 non-COVID). Median age was 58 years (interquartile range [IQR], 47-67 yr) and Acute Physiology and Chronic Health Evaluation II scores of 30 (IQR, 21-36). In COVID-19 patients, the frequency of R-L shunt was 31 of 182 COVID patients (17.0%) versus 10 of 44 non-COVID patients (22.7%), with no difference detected in shunt rates (risk difference [RD], -5.7%; 95% CI, -18.4 to 7.0; p = 0.38). In the COVID-19 group, hospital mortality was higher for those with R-L shunt compared with those without (54.8% vs 35.8%; RD, 19.0%; 95% CI, 0.1-37.9; p = 0.05). This did not persist at 90-day mortality nor after adjustment with regression.

CONCLUSIONS

There was no evidence of increased R-L shunt rates in COVID-19 compared with non-COVID controls. R-L shunt was associated with increased in-hospital mortality for COVID-19 patients, but this did not persist at 90-day mortality or after adjusting using logistic regression.

Critical Care Experience With Clinical Cerebral Autoregulation Testing in Adults With Traumatic Brain Injury

BACKGROUND

To describe the setting, feasibility, and safety of static cerebral autoregulation testing in critically injured adults with traumatic brain injury (TBI).  Methods: We reviewed static autoregulation testing using transcranial Doppler (TCD) ultrasound in patients > 18 years with TBI ICD codes between January 1, 2014, and December 31, 2021. Adverse events during testing were defined as systemic hypertension (systolic blood pressure (SBP>180 mmHg), bradycardia (HR<40 bpm), and high ICP (>30 mmHg). Impaired and absent cerebral autoregulation was defined as an autoregulatory index (ARI) <0.4 and ARI 0, respectively. We characterized prescribed changes in intracranial pressure (ICP) and cerebral perfusion pressure (CPP) targets by autoregulation testing results.  Results: A total of 135 patients, median age 31 (interquartile range (IQR) 24, 43) years, 71.9% male, admission Glasgow coma scale (GCS) score 3 (IQR 3, 5.5), and 70.9% with subdural hematoma from severe (GCS 3-8; 133 (98.5%)) and moderate (GCS 9-12; 2 (1.5%)) TBI, underwent 309 attempted testing. All patients were mechanically ventilated and had ICP monitoring; 246 (80%) had brain tissue oxygen monitoring, and 68 (22%) had an external ventricular drain. The median number of autoregulation tests was two (range 1-3) tests/patient, and the median admission to the first test time was two days (IQR 1, 3). Of 55 (17.8%) tests not completed, systemic hypertension (32, 10.4%), intracranial hypertension (10, 3.2%), and bradycardia (3, 0.9%) were transient. Fifty-three (51%) of the first (n=104) autoregulation tests showed impaired/absent cerebral autoregulation. Impaired/absent autoregulation results at the first test were associated with repeat cerebral autoregulation testing (RR 2.25, 95% CI [1.40-3.60], p=0.0007) than intact cerebral autoregulation results. Pre-testing cerebral hemodynamic targets were maintained (n=131; 86.8%) when cerebral autoregulation was impaired (n=151; RR 1.49, 95% CI [1.25-1.77], p<0.0001). However, 15 (9.9%) test results led to higher ICP targets (from 20 mmHg to 25 mmHg), 5 (3.3%) results led to an increase in CPP target (from 60 mmHg to 70 mmHg), and five out of 131 (3.8%) patients underwent decompressive craniectomy and placement of an external ventricular drain. Intact cerebral autoregulation results (n=43/103, 41.7%) were associated with a change in ICP targets from 20 mmHg to 25 mmHg (RR 3.15, 95% CI [1.97-5.03], p<0.0001).  Conclusions: Static cerebral autoregulation testing was feasible, safe, and useful in individualizing the care of patients with moderate-severe TBI receiving multimodal neuromonitoring. Testing results guided future testing, cerebral hemodynamic targets, and procedural decisions. Impaired cerebral autoregulation was very common.

Effects of pneumoperitoneum and Trendelenburg position on intracranial pressure and cerebral blood flow assessed using transcranial doppler: A prospective observational study

Background and Aims

Laparoscopic lower abdominal surgeries involve carbon dioxide (CO2) insufflation and Trendelenburg position. The raised intra-abdominal pressure can increase intracranial pressure (ICP) and alter cerebral blood flow. This study was conducted to determine the effect of pneumoperitoneum and Trendelenburg position on ICP and cerebral perfusion pressure (CPP) measured using transcranial Doppler (TCD).

Material and Methods

A prospective observational study was conducted in 43 patients of either sex, aged between 18 and 60 years with American Society of Anesthesiologists physical status I and II, undergoing elective laparoscopic surgery in Trendelenburg position. After standard anesthesia induction, pneumoperitoneum was created to facilitate surgery, maintaining an intra-abdominal pressure of 10-15 mmHg and Trendelenburg position of 25°-30°. End-tidal carbon dioxide (EtCO2) was maintained between 30 and 35 mmHg. The ICP was assessed non-invasively using TCD-based diastolic flow velocities (FVd) and pulsatility index (PI) of middle cerebral artery. Data was represented as mean ± standard deviation and compared using paired t test. A P value of < 0.05 was considered significant.

Results

Mean ICPPI at baseline was 14.02 ± 0.89 mmHg which increased to 14.54 ± 1.21 mmHg at pneumoperitoneum and Trendelenburg position (P = 0.005). Mean ICPFVd at baseline was 6.25 ± 2.47 mmHg which increased to 8.64 ± 3.79 mmHg at pneumoperitoneum and Trendelenburg position (P < 0.001). There was no statistically significant change in the CPP or mean arterial pressure values intraoperatively.

Conclusions

Laparoscopic procedures with CO2 pneumoperitoneum in Trendelenburg position increase ICP as measured using TCD ultrasonography. The CPP was not significantly altered when EtCO2 was maintained in the range of 30-35 mmHg.

Brain monitoring after cardiac arrest

PURPOSE OF REVIEW

To describe the available neuromonitoring tools in patients who are comatose after resuscitation from cardiac arrest because of hypoxic-ischemic brain injury (HIBI).

RECENT FINDINGS

Electroencephalogram (EEG) is useful for detecting seizures and guiding antiepileptic treatment. Moreover, specific EEG patterns accurately identify patients with irreversible HIBI. Cerebral blood flow (CBF) decreases in HIBI, and a greater decrease with no CBF recovery indicates poor outcome. The CBF autoregulation curve is narrowed and right-shifted in some HIBI patients, most of whom have poor outcome. Parameters derived from near-infrared spectroscopy (NIRS), intracranial pressure (ICP) and transcranial Doppler (TCD), together with brain tissue oxygenation, are under investigation as tools to optimize CBF in patients with HIBI and altered autoregulation. Blood levels of brain biomarkers and their trend over time are used to assess the severity of HIBI in both the research and clinical setting, and to predict the outcome of postcardiac arrest coma. Neuron-specific enolase (NSE) is recommended as a prognostic tool for HIBI in the current postresuscitation guidelines, but other potentially more accurate biomarkers, such as neurofilament light chain (NfL) are under investigation.

SUMMARY

Neuromonitoring provides essential information to detect complications, individualize treatment and predict prognosis in patients with HIBI.

The Clinical Impact of Recent Methamphetamine Exposure in Aneurysmal Subarachnoid Patients

Background

Methamphetamines (MA) are a frequently used drug class with potent sympathomimetic properties that can affect cerebral vasculature. Conflicting reports in literature exist about the effect of exposure to MA on vasospasm risk and clinical outcomes in aneurysmal subarachnoid hemorrhage (aSAH). This study aimed to characterize the impact of recent MA use on the timing, severity and features of vasospasm in aneurysmal subarachnoid as well as neurological outcomes.

Methods

We retrospectively screened 441 consecutive patients admitted to a tertiary care hospital with a diagnosis of SAH who underwent at least one cerebral digital subtraction angiogram (DSA). Patients were excluded if no urinary toxicology screen was performed within 24 hours of admission, if there was a diagnosis of non-aneurysmal SAH, or if ictus was greater than 72 hours from hospital admission. Vasospasm characteristics were collected from DSA and transcranial doppler (TCD) studies and demographic as well as clinical outcome data was abstracted from the chart.

Results

129 patients were included and 24 tested positive for MA. Among the 312 excluded patients, 281 did not have a urinary toxicology screen and 31 had a non-aneurysmal pattern of SAH or ictus occurring greater than 72 hours from hospital admission. No significant differences were found in respect to patient age, sex, or admission Hunt and Hess Score or Modified Fisher Scale based on MA use. There was no difference in the severity of vasospasm or time to peak severity using either TCD or DSA criteria on multivariate analysis. Aneurysms were more likely to be in the anterior circulation for both groups, however the MA cohort experienced less vasospasm involving the anterior circulation and more isolated posterior circulation vasospasm. There was no difference in delayed cerebral ischemia (DCI) incidence, length of ICU stay, need for ventriculoperitoneal shunt placement, functional outcome at discharge or hospital mortality.

Interpretation

Recent MA use was not associated with worse vasospasm severity, time to vasospasm, or DCI in aSAH patients. Further investigations about localized MA effects in the posterior circulation and impact on long-term functional outcomes are warranted.

Repeat transcranial Doppler ultrasound imaging in Kuwaiti children with sickle cell disease after a 10‐year interval: A prospective, cohort study

Objectives

Transcranial Doppler imaging (TCDI) of the cerebral arteries is the method of choice to predict patients with sickle cell disease (SCD) at risk for stroke. This study reports TCDI follow‐up of cerebral blood flow in a cohort of Kuwaiti children with SCD after a 10‐year interval.

Methods

Twenty‐one pediatric patients with SCD, aged 16.0 ± 1.6 years were initially studied when they were aged 6.5 ± 1.2 years. TCDI scanning was carried out using a phased‐array transducer of 1–3 MHz through the trans‐temporal window. Peak systolic velocity (PSV), end‐diastolic velocity (EDV), time‐averaged mean of the maximum velocity (TAMMV), resistive index (RI), and pulsatility index (PI) were obtained in the anterior and posterior Circle of Willis vessels.

Results

The follow‐up indices were mostly lower than in the initial study although they remained within the normal range in all the arteries. TAMMV was less than 170 cm/s, and PSV did not exceed 200 cm/s in all vessels. The initial and follow‐up TAMMV (mean ± SD) were: 77.3 ± 20.9 and 71.6 ± 9.9 in the terminal internal carotid artery, 94.3 ± 25.8 and 82 ± 18.2 in the middle cerebral artery, 76.6 ± 25.6 and 70.6 ± 10.7 in the anterior cerebral artery, and 59.1 ± 15.8 and 63.9 ± 8.5 in the posterior cerebral artery, respectively. The mean differences between the old and follow‐up data for RI, and PI were statistically significant (p < 0.05).

Conclusions

Kuwaiti patients with SCD appear to be largely protected from cerebral artery vasculopathy in childhood.

Stroke is a common complication in sickle cell disease (SCD) in many parts of the world and it tends to be recurrent.

Transcranial Doppler Imaging (TCDI) is used to identify patients at risk for stroke.

Patients with timed average mean of the maximum velocity (TAMMV) > 200 cm/s in the arteries of the Circle of Willis, are at increased risk of stroke and need chronic transfusion for the primary prevention of stroke.

However, stroke is uncommon among Kuwaiti SCD patients with high HbF.

A previous study carried out, about 10 years ago, in a cohort of Kuwaiti pediatric SCD found none with abnormal TAMMV values.

A repeat TCDI study has now been carried out on 21 patients from the cohort that was studied 10 years ago.

We found that TCD remains in the normal range in all the patients and, in fact, the TAMMV and other values were significantly lower in the latest study compared to the initial data.

Cerebral vasculopathy is uncommon among Kuwaiti SCD patients.

Evaluation of transcranial Doppler use in patients with acute liver failure listed for emergency liver transplantation

PURPOSE

Acute liver failure (ALF) is characterized by hepatic encephalopathy (HE) often due to intracranial hypertension (ICH). The risk/benefit-balance of intraparenchymal pressure catheter monitoring is controversial during ALF.

AIMS

Perform an evaluation of transcranial Doppler (TCD) use in patients with ALF listed for emergency liver transplantation.

MATERIAL AND METHODS

Single center retrospective cohort study including all patients registered on high emergency LT list between 2012 and 2018. All TCD measurements performed during ICU stay after listing and after LT (when performed) were recorded. TCD was considered abnormal when pulsatility index (PI) was >1.2.

RESULTS

Among 106 patients with ALF, forty-seven (44%) had a TCD while on list. They had more severe liver and extrahepatic organ failure. When performed, TCD was abnormal in 51% of patients. These patients more frequently developed ICH events (45% vs. 13%, p = .02) and more frequently required increase in sedative drugs and vasopressors. While 22% of patients with normal TCD spontaneously survived, all of those with abnormal TCD died or were transplanted (p = .02). All transplanted patients who had abnormal exams normalized their TCD within 2 (1-2) days after LT.

CONCLUSION

TCD may be a useful non-invasive tool for ICH detection and management, then guide sedation withdrawal.

Vasospasm Management Strategies

Aim-

In this study, we present a broad presentation of the current state of cerebral vasospasm, including its pathogenesis, commonly used treatments, and future outlook.

Methods-

A literature review was conducted for cerebral vasospasms using the PubMed journal database (https://pubmed.ncbi.nlm.nih.gov). Relevant journal articles were narrowed down and selected using the Medical Subject Headings (MeSH) option in PubMed.

Results-

Cerebral vasospasm is the persistent narrowing of cerebral arteries days after experiencing a subarachnoid hemorrhage (SAH). Eventually, if not corrected, this can lead to cerebral ischemia with significant neurological deficits and/or death. Therefore, it is clinically beneficial to diminish or prevent the occurrence or reoccurrence of vasospasm in patients following a SAH to prevent unwanted comorbidities or fatalities. We discuss the pathogenesis and mechanism of development that have been implicated in the progression of vasospasms as well as the manner in which clinical outcomes are quantitively measured. Further, we mention and highlight commonly used treatments to inhibit and reverse the course of vasoconstriction within the cerebral arteries. Additionally, we mention innovations and techniques that are being used to treat vasospasms and the outlook of their therapeutic value.

Conclusion-

Overall, we give a comprehensive summary of the disease that encapsulates cerebral vasospasm and the current and future standards of care that are used to treat it.

Transcranial Doppler Ultrasonography-Related Research in the Caribbean Region

Transcranial Doppler (TCD) ultrasonography is a non-invasive ultrasound technique that uses high-frequency sound waves to measure blood flow velocities in the cerebral vasculature. This review analyzes TCD research in the Caribbean region using a bibliometric analysis of 29 articles from PubMed. The articles were analyzed using Microsoft Excel 2016 and the VOSviewer software (Van Eck and Waltman, Leiden University, Centre for Science and Technology Studies (CWTS), www.vosviewer.com) and characterized various aspects of TCD research, including countries, research themes, authorship, journals, affiliations, and keywords. The majority of the 29 publications came from Cuba (38%), followed by the French West Indies (22%) and Jamaica (20%). Most TCD research focused on sickle cell disease (SCD), accounting for 45% of the studies, followed by 21% of articles on vasospasm and subarachnoid hemorrhage. The use of TCD in brain death and neuro-intensive care was also explored, constituting 17% of the studies. Alternative TCD-monitored treatment options for SCD, such as stem cell transplantation and hydroxyurea, were also frequently investigated. The most productive institutions were Hospital Clínico-Quirúrgico Hermanos Ameijeiras in Havana, Cuba, the Sickle Cell Unit at the University of West Indies (UWI) Mona in Jamaica, the Medical-Surgical Research Center (CIMEQ) in Havana, Cuba, and the SCD Reference Center in Guadeloupe and Martinique in the French West Indies. TCD has been identified as a cost-effective tool for real-time monitoring of cerebral blood flow in many clinical settings, including stroke and SCD, which are prevalent in the Caribbean. Although there is an increase in the trend of using TCD for neuromonitoring in the Caribbean, gaps still exist. Capacity-building initiatives, such as training programs for healthcare providers and the development of local TCD research networks, can improve access to TCD in resource-constrained settings to treat and neuromonitor patients cost-effectively.

Relationship between Middle Cerebral Artery Pulsatility Index and Delayed Neurocognitive Recovery in Patients undergoing Robot-Assisted Laparoscopic Prostatectomy

A steep Trendelenburg (ST) position combined with pneumoperitoneum may cause alterations in cerebral blood flow with the possible occurrence of postoperative cognitive disorders. No studies have yet investigated if these alterations may be associated with the occurrence of postoperative cognitive disorders. The aim of the study was to evaluate the association between an increased middle cerebral artery pulsatility index (Pi), measured by transcranial doppler (TCD) 1 h after ST combined with pneumoperitoneum, and delayed neurocognitive recovery (dNCR) in 60 elderly patients undergoing robotic-assisted laparoscopic prostatectomy (RALP). Inclusion criteria were: ≥65 years; ASA class II-III; Mini-Mental Examination score > 23. Exclusion criteria were: neurological or psychiatric pathologies; any conditions that could interfere with test performance; severe hypertension or vascular diseases; alcohol or substance abuse; chronic pain; and an inability to understand Italian. dNCR was evaluated via neuropsychological test battery before and after surgery. Anesthesia protocol and monitoring were standardized. The middle cerebral artery Pi was measured by TCD, through the trans-temporal window and using a 2.5 MHz ultrasound probe at specific time points before and during surgery. In total, 20 patients experiencing dNCR showed a significantly higher Pi after 1 h from ST compared with patients without dNCR (1.10 (1.0-1.19 95% CI) vs. 0.87 (0.80-0.93 95% CI); p = 0.003). These results support a great vulnerability of the cerebral circulation to combined ST and pneumoperitoneum in patients who developed dNCR. TCD could be used as an intraoperative tool to prevent the occurrence of dNCR in patients undergoing RALP.

Use of duplex echoencephalography to evaluate brain death in children: A novel approach to the diagnosis

BACKGROUND AND PURPOSE

Brain death is defined as the irreversible cessation of brain function with a known etiology. This study aims to establish the value of duplex echoencephalography (DEG) in children fulfilling clinical brain death diagnostic criteria.

METHODS

DEG must show intracranial brain structures. Power Doppler is used to assess venous flow when feasible. Color Doppler patterns in all major arteries are assessed. Spectral analysis of arterial flow is divided into four grades: grade 1: inverted flow during entire diastole with time average peak velocity (TAPV) less or equal to zero; grade 2: disappearance of the inverted diastolic flow at the end of diastole; grade 3: oscillating pattern in early diastole; and grade 4: no diastolic flow with systolic blip. To fulfill diagnosis of brain death, brain perfusion must be lost for 30 minutes.

RESULTS

DEG is performed in 41 pediatric patients. In infants, loss of venous flow occurs regardless of the etiology. Grade 1 is the most common arterial color flow pattern and TAPV is always below zero. A pulsatile color flow is associated with three other types of flow patterns (grades 2-4). TAPV is not calculated, when there is loss of diastolic flow. Diagnosis of brain death is validated using nuclear brain scan in 4 patients. Two have a grade 1 flow pattern, while the other two have a grade 4 flow pattern.

CONCLUSIONS

In children, DEG following a strict protocol can be used to confirm diagnosis of brain death in the appropriate clinical setting.

Pediatric Sickle Cell Disease and Stroke: A Literature Review

Both ischemic and hemorrhagic strokes in children can be a complication of sickle cell disease, which also affects adults. The occurrence is high without any screening or preventative care. This review article found that although transcranial Doppler (TCD) has reduced the prevalence of stroke in pediatric patients, there is still a need for an epidemiological survey to define such screening for adults, the ideal dose of hydroxyurea to reduce the incidence of stroke, and to identify silent cerebral stroke to prevent its complications. Increased hydroxyurea prescription and specific antibiotic and vaccination regimes lowered the occurrence of this condition. In pediatric cases with a time-averaged mean of the maximal velocity greater than 200cm/s, transcranial Doppler screening and preventive chronic transfusion for at least the first year have lowered the occurrence of stroke by up to 10 times. The ideal dose of hydroxyurea is still debatable, but it seems to reduce the risk of the first stroke to a comparable level in the average population. Adult ischemic and hemorrhagic stroke prevention has not yet received the same attention. Though there are fewer studies, sickle cell disease is also more common than age-matched controls in terms of silent cerebral infarction on magnetic resonance imaging (MRI), as well as other neurological problems such as cognitive impairment, seizures, and headaches. Currently, there is no evidence-supported way to prevent ischemic stroke in adults at any age. Also, there is no defined ideal dose of hydroxyurea that can be helpful in preventing strokes. Data also lack a way to identify a silent cerebral infarction, so its complications can be prevented. An additional epidemiological survey may help in the prevention of the condition. The primary aim of this article was to emphasize the importance of information on clinical, neuropsychological, and quantitative MRI assessment of sickle cell patients to understand the epidemiology and etiology of stroke in sickle cell patients to prevent stroke and its related morbidity.

Development and Validation of Machine Learning Models to Classify Artery Stenosis for Automated Generating Ultrasound Report

Duplex ultrasonography (DUS) is a safe, non-invasive, and affordable primary screening tool to identify the vascular risk factors of stroke. The overall process of DUS examination involves a series of complex processes, such as identifying blood vessels, capturing the images of blood vessels, measuring the velocity of blood flow, and then physicians, according to the above information, determining the severity of artery stenosis for generating final ultrasound reports. Generation of transcranial doppler (TCD) and extracranial carotid doppler (ECCD) ultrasound reports involves a lot of manual review processes, which is time-consuming and makes it easy to make errors. Accurate classification of the severity of artery stenosis can provide an early opportunity for decision-making regarding the treatment of artery stenosis. Therefore, machine learning models were developed and validated for classifying artery stenosis severity based on hemodynamic features. This study collected data from all available cases and controlled at one academic teaching hospital in Taiwan between 1 June 2020, and 30 June 2020, from a university teaching hospital and reviewed all patients' medical records. Supervised machine learning models were developed to classify the severity of artery stenosis. The receiver operating characteristic curve, accuracy, sensitivity, specificity, and positive and negative predictive value were used for model performance evaluation. The performance of the random forest model was better compared to the logistic regression model. For ECCD reports, the accuracy of the random forest model to predict stenosis in various sites was between 0.85 and 1. For TCD reports, the overall accuracy of the random forest model to predict stenosis in various sites was between 0.67 and 0.86. The findings of our study suggest that a machine learning-based model accurately classifies artery stenosis, which indicates that the model has enormous potential to facilitate screening for artery stenosis.

Investigation of Cerebral Autoregulation Using Time-Frequency Transformations

The authors carried out the study of the state of systemic and cerebral hemodynamics in normal conditions and in various neurosurgical pathologies using modern signal processing methods. The results characterize the condition for the mechanisms of cerebral circulation Institute of Computer Science and Control, Higher School of Cyber-Physical Systems and Control regulation, which allows for finding a solution to fundamental and specific clinical problems for the effective treatment of patients with various pathologies. The proposed method is based on the continuous wavelet transform of systemic arterial pressure and blood flow velocity signals in the middle cerebral artery recorded by non-invasive methods of photoplethysmography and transcranial doppler ultrasonography. The study of these signals in real-time in the frequency range of Mayer waves makes it possible to determine the cerebral autoregulation state in certain diseases before and after surgical interventions. The proposed method uses a cross-wavelet spectrum, which helps obtain wavelet coherence and a phase shift between the wavelet coefficients of systemic arterial pressure signals and blood flow velocity in the Mayer wave range. The obtained results enable comparing the proposed method with that based on the short-time Fourier transform. The comparison showed that the proposed method has higher sensitivity to changes in cerebral autoregulation and better localization of changes in time and frequency.

Early diagnosis of cerebral vasospasm associated with cerebral ischemia following subarachnoid hemorrhage: Evaluation of computed tomography perfusion and transcranial doppler as accurate methods

Cerebral vasospasm (CV) constitutes a major post-operative complication and source of morbidity in cases of subarachnoid hemorrhage (SAH). The early detection of CV in SAH may be difficult both clinically and radiographically. The present pilot study thus aimed to evaluate the practicability of the technique in a tertiary healthcare setting and to assess the diagnostic effectiveness of various diagnostic computed tomography (CT) perfusion (CTP) aspects in predicting the clinical outcome of patients with SAH (traumatic and aneurysmal). A retrospective study including 34 patients in a tertiary care hospital was thus conducted. The results revealed that of the 34 patients, 18 (52.9%) were males, and the mean age was 54.4±18.5 years (16-85 years old; range, 69 years). In total, 15 (44.1%) patients had traumatic SAH following traumatic brain injury (TBI), 11 (33.3%) had aneurysmal SAH, and 8 patients (23.6%) presented with TBI without SAH as controls. CTP was performed on the third to the sixth day, and 15-20 min prior to CPT, a transcranial Doppler ultrasound was performed. Clinical outcomes were documented at 30 days using a CT scan and a complete neurological evaluation, including Glasgow Coma Scale assessment. The results of a multivariate analysis revealed that cerebral blood flow (CBF) was an independent factor for detecting an ischemic event in 1 month (P=0.003). On the whole, the present study demonstrates that CTP, and consequently CBF, is a considerable index that may identify the onset of cerebral ischemia in patients with SAH.

Associations Between Transcranial Doppler Vasospasm and Clinical Outcomes After Aneurysmal Subarachnoid Hemorrhage: A Retrospective Observational Study

OBJECTIVE

The objective is to examine the relationship between transcranial Doppler cerebral vasospasm (TCD-vasospasm), and clinical outcomes in aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

In a retrospective cohort study, using univariate and multivariate analysis, we examined the association between TCD-vasospasm (defined as Lindegaard ratio >3) and patient's ability to ambulate without assistance, the need for tracheostomy and gastrostomy tube placement, and the likelihood of being discharged home from the hospital.

RESULTS

We studied 346 patients with aSAH; median age 55 years (Interquartile range IQR 46,64), median Hunt and Hess 3 [IQR 1-5]. Overall, 68.6% (n=238) had TCD-vasospasm, and 28% (n=97) had delayed cerebral ischemia. At hospital discharge, 54.3% (n=188) were able to walk without assistance, 5.8% (n=20) had received a tracheostomy, and 12% (n=42) had received a gastrostomy tube. Fifty-three percent (n=183) were discharged directly from the hospital to their home. TCD-vasospasm was not associated with ambulation without assistance at discharge (adjusted odds ratio, aOR 0.54, 95% 0.19,1.45), tracheostomy placement (aOR 2.04, 95% 0.23,18.43), gastrostomy tube placement (aOR 0.95, 95% CI 0.28,3.26), discharge to home (aOR 0.36, 95% CI 0.11,1.23).

CONCLUSION

This single-center retrospective study finds that TCD-vasospasm is not associated with clinical outcomes such as ambulation without assistance, discharge to home from the hospital, tracheostomy, and gastrostomy feeding tube placement. Routine screening for cerebral vasospasm and its impact on vasospasm diagnostic and therapeutic interventions and their associations with improved clinical outcomes warrant an evaluation in large, prospective, case-controlled, multi-center studies.

Neurocognitive functioning in children with sickle cell anemia and history of abnormal transcranial doppler ultrasonography

BACKGROUND

Transcranial doppler (TCD) ultrasonography can be used to identify stroke risk in children with sickle cell anemia. Previous studies have reported mixed findings on neurocognitive outcomes in children with elevated TCD. This study examined associations between TCD velocity and neurocognitive outcomes in children and adolescents without prior history of stroke.

PROCEDURE

Participants were selected from the Sickle Cell Clinical Research Intervention Program cohort. The highest recorded mean maximum TCD velocity was selected for analysis, along with participant's most recent data from serial neurocognitive surveillance.

RESULTS

A total of 200 children with sickle cell anemia completed neurocognitive testing (109 males, 91 females; mean age 12.7 years [SD = 3.56]). Most participants were prescribed hydroxyurea (72%) at the time of neurocognitive testing and nearly 16% had a history of chronic transfusions prior to neurocognitive evaluation. Mean age at time of highest TCD value was 6.6 years (SD = 2.5) and 13.5% of screenings were abnormal (≥200 cm/s). Mean interval between TCD and most recent neurocognitive evaluation was 6.1 years (±3.5). There were no significant differences in the interval between TCD and neurocognitive testing across normal, conditional, and abnormal groups. Maximum TCD velocity was not significantly associated with neurocognitive outcomes in multivariate models.

CONCLUSIONS

History of elevated TCD in the absence of overt stroke should not be considered a risk factor for poor neurocognitive outcomes in children and adolescents with sickle cell anemia on modern disease-modifying therapy.

Residual Right-to-Left-Shunt Following Transcatheter Patent Foramen Ovale Closure: The Role of Antithrombotic Treatment

BACKGROUND

Transcatheter closure of patent foramen ovale (PFO) is a highly effective therapy for patients with left circulation thromboembolism, not attributable to other conditions.

OBJECTIVES

This retrospective cohort study investigates the impact of baseline foramen ovale anatomy on the severity of the postclosure shunt.

METHODS

Patients with PFO, who underwent percutaneous closure, were followed up for at least 5 years postimplantation. Patients were classified into two groups based on the presence of high-risk features of the baseline PFO anatomy. At the follow-up follow-up, residual right-to-left shunt was assessed for the high and non-highrisk anatomy groups, via transcranial Doppler at rest and after performing the Valsalva maneuver, with the injection of agitated saline.

RESULTS

38 patients were examined after a mean follow-up period of 9 ± 3 years after implantation. After retrospective evaluation of the baseline transthoracic and transesophageal echo studies, 14 patients with high-risk PFO anatomy were identified. The degree of the residual right-to-left shunt, as assessed by the number of microbubbles was higher in the high-risk PFO anatomy group compared to the non-high-risk group, both at rest [1.50 (IQR: 0.00-3.25) vs. 0.00 (IQR: 0.00-0.00), p < 0.001] and post-Valsalva maneuver [7.50 (IQR: 1.50- 10.25) vs. 0.00 (IQR: 0.00-3.75), p = 0.003]. Furthermore, in the high-risk group, more microbubbles were detected at rest (p = 0.008) and post-Valsalva (p = 0.002) in subjects without antiplatelet treatment compared to subjects on prolonged antiplatelet therapy.

CONCLUSION

Baseline PFO anatomy affects the severity of the residual right-to-left shunt. Prolonged antiplatelet therapy may benefit patients with high-risk anatomical features.

Emergent neurovascular imaging in patients with blunt traumatic injuries

Blunt cerebrovascular injuries (BCVIs) are commonly encountered after blunt trauma. Given the increased risk of stroke incurred after BCVI, it is crucial that they are promptly identified, characterized, and treated appropriately. Current screening practices generally consist of computed tomography angiography (CTA), with escalation to digital subtraction angiography for higher-grade injuries. Although it is quick, cost-effective, and readily available, CTA suffers from poor sensitivity and positive predictive value. A review of the current literature was conducted to examine the current state of emergent imaging for BCVI. After excluding reviews, irrelevant articles, and articles exclusively available in non-English languages, 36 articles were reviewed and included in the analysis. In general, as CTA technology has advanced, so too has detection of BCVI. Magnetic resonance imaging (MRI) with sequences such as vessel wall imaging, double-inversion recovery with black blood imaging, and magnetization prepared rapid acquisition echo have notably improved the utility for MRI in characterizing BCVIs. Finally, transcranial Doppler with emboli detection has proven to be associated with strokes in anterior circulation injuries, further allowing for the identification of high-risk lesions. Overall, imaging for BCVI has benefited from a tremendous amount of innovation, resulting in better detection and characterization of this pathology.

Role of Bedside Transcranial Ultrasonography in the Assessment of Cerebral Hemodynamics in Decompressive Craniectomy Patients with Cranioplasty: A Single Centre Experience

BACKGROUND

Intracerebral hemorrhage is a leading cause of death and disability worldwide. After intracerebral hemorrhage, cerebral blood flow (CBF) becomes extremely low approaching ischemic thresholds. Concurrently, CBF velocities become strongly correlated to CBF itself post-injury. Identification of such hemodynamic disturbances can be used to predict outcome immediately post-injury when indices are measured using transcranial doppler ultrasonography (TCD). TCD permits non-invasive assessment of different CBF velocities as well as pulsatility index (PI). Abnormal measurement of such indices is believed to correlate to poor outcome.

AIM

To investigate the effect of cerebral hemodynamics after cranioplasty in decompressive craniectomy patients using pre and postoperative TCD.

MATERIALS AND METHODS

This study is a prospective study of 3 years duration undertaken on 64 patients. All the patients were evaluated by TCDbefore and after decompressive craniectomy.All patients were evaluated by transcranial Doppler (TCD) 1 week before and 7-15 days after cranioplasty. TCD results were obtained though trans-temporal approach.

RESULTS

Statistically significant differences between the values before and after craniectomy were detected in Peak Systolic Volume (PSV) for the Anterior Cerebral Artery (ACA) (P = 0.001), in PSV for the Middle Cerebral Artery (MCA) (P < 0.004), in Mean Bloodflow Velocity (MV) for the MCA (P < 0.003), and in PSV for the Posterior Cerebral artery (PCA) (P = 0.001) on the ipsilateral side. There were statistically significant differences between the values before and after cranioplasty in PSV for the PCA (P = 0.004), on contralateral side.After decompressive craniectomy, the PI values for the MCA decreased, on average, to 31+/- 33% of the pre-surgical value in the treated side and to 28+/- 31% on the opposite side. On the other hand, the mean PI values for the extracranial ICA reduced to 34+/- 21% of the initial values in the treated side, and to 21+/- 31% on the opposite side.Cranioplasty improved CBF velocities in all major intracrainal arteries, not only on the side of the lesion adjacent to the cranioplasty, but also in distant regions, such as in the contralateral hemisphere.

CONCLUSION

Decompressive craniectomy significantly improves cerebral hemodynamics both on ipsilateral and contralateral cerebral hemispheres.Concomitantly, PI values on TCD decrease significantly postoperatively, mainly in the decompressed cerebral hemisphere, indicating reduction in cerebrovascular resistance. We conclude that cranioplasty improves neurological status and the mechanism of postoperative improvement of neurological status may be due to increased CBF velocity.

Cerebral hemodynamics in children with sickle cell disease in India: An observational cohort study

India has the second highest number of cases of sickle cell disease (SCD) and affects the most socioeconomically disadvantaged communities living in a horizontal belt from Gujarat to Odisha state. Despite high prevalence, information about cerebral hemodynamics among children with SCD in India remains scarcely described. We performed transcranial Doppler (TCD) to assess cerebral hemodynamics among Indian children with SCD and evaluated their association with clinical and hematological parameters. Children aged 3-18years, diagnosed with SCD living in Raipur in Chhattisgarh and Ahmedabad in Gujarat state were recruited. TCD was performed to obtain flow velocities from middle cerebral (MCA), intracranial internal carotid (ICA) and basilar artery. Associations were evaluated between timed-average-mean-maximum velocities (TAMMV) and various clinical and hematological parameters. Our prospective study included 62 consecutive children with known SCD. Mean ± SD age of the study population was 9.8 ± 3.9 years and 31 (50%) were male. Mean ± SD hemoglobin was 8.64 ± 1.34 Gm/dL while the mean HbSS ± SD was 70.25 ± 15.27%. While 6 (9.6%) children had suffered from stroke during previous 2 years, 7 (11%) demonstrated abnormal TAMMV. Higher HbSS level along with history of iron chelation therapy, blood transfusion and/or stroke showed a trend towards having higher TAMMV. Stroke and cerebral hemodynamic alterations are common among Indian children with SCD. Larger studies with detailed neuroimaging and genetic evaluations are needed for better understanding, characterization, risk stratification as well as optimization of the timing of blood transfusion to reduce physical disabilities among Indian children with SCD.

Acute pontine infarction in a patient with 8-shaped basilar artery fenestration malformation: A case report

INTRODUCTION

Cerebrovascular fenestration malformation is a relatively rare vascular dysplasia, and an 8-shaped basilar artery fenestration malformation is even rarer. The characteristics of transcranial Doppler cerebral blood flow in cerebrovascular fenestration malformations have rarely been studied or reported.

PATIENT CONCERNS

A 58-year-old woman presented with hypertension, diabetes, with no history of smoking or drinking. The patient had no relevant family history. The patient experienced left limb weakness for 2 days, which gradually worsened.

DIAGNOSIS

Head and neck computed tomography angiography revealed an 8-shaped fenestration deformity of the lower segment of the basilar artery with multiple stenoses of the local vessels. Transcranial Doppler cerebral blood flow examination at a depth of 85 cm revealed an eddy current in the lower segment of the basilar artery.

INTERVENTIONS

Tirofiban was administered intravenously for 3 days and subsequently changed to oral clopidogrel antiplatelet treatment.

OUTCOMES

The modified Rankin Scale score at 3 months after disease onset was 0, indicating that the patient recovered well after treatment.

CONCLUSION

A basilar artery 8-shaped fenestration is extremely rare and has seldom been reported. Cerebral vascular fenestration can lead to an acute cerebral infarction and its pathogenesis may include local hemodynamic abnormalities and thrombosis. Eddy currents can be detected by transcranial Doppler cerebral blood flow examination.

Menstrual cycle and oral contraceptives influence cerebrovascular dynamics during hypercapnia

Women experience fluctuating orthostatic intolerance during the menstrual cycle, suggesting sex hormones may influence cerebral blood flow. Young (aged 18-30) healthy women, either taking oral contraceptives (OC; n = 14) or not taking OC (NOC; n = 12), were administered hypercapnic gas (5%) for 5 min in the low hormone (LH; placebo pill) and high hormone (HH; active pill) menstrual phases. Hemodynamic and cerebrovascular variables were continuously measured. Cerebral blood velocity changes were monitored using transcranial doppler ultrasound of the middle cerebral artery to determine cerebrovascular reactivity. Cerebral autoregulation was assessed using steady-state analysis (static cerebral autoregulation) and transfer function analysis (dynamic cerebral autoregulation; dCA). In response to hypercapnia, menstrual phase did not influence static cardiovascular or cerebrovascular responses (all p > 0.07); however, OC users had a greater increase of mean middle cerebral artery blood velocity compared to NOC (NOC-LH 12 ± 6 cm/s vs. NOC-HH 16 ± 9 cm/s; OC-LH 18 ± 5 cm/s vs. OC-HH 17 ± 11 cm/s; p = 0.048). In all women, hypercapnia improved high frequency (HF) and very low frequency (VLF) cerebral autoregulation (decreased nGain; p = 0.002 and <0.001, respectively), whereas low frequency (LF) Phase decreased in NOC-HH (p = 0.001) and OC-LH (p = 0.004). Therefore, endogenous sex hormones reduce LF dCA during hypercapnia in the HH menstrual phase. In contrast, pharmaceutical sex hormones (OC use) have no acute influence (HH menstrual phase) yet elicit a chronic attenuation of LF dCA (LH menstrual phase) during hypercapnia.

The Utility of Quantitative EEG in Detecting Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

SUMMARY

In this review, we discuss the utility of quantitative EEG parameters for the detection of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage in the context of the complex pathophysiology of DCI and the limitations of current diagnostic methods. Because of the multifactorial pathophysiology of DCI, methodologies solely assessing blood vessel narrowing (vasospasm) are insufficient to detect all DCI. Quantitative EEG has facilitated the exploration of EEG as a diagnostic modality of DCI. Multiple quantitative EEG parameters such as alpha power, relative alpha variability, and alpha/delta ratio show reliable detection of DCI in multiple studies. Recent studies on epileptiform abnormalities suggest that their potential for the detection of DCI. Quantitative EEG is a promising, continuous, noninvasive, monitoring modality of DCI implementable in daily practice. Future work should validate these parameters in larger populations, facilitated by the development of automated detection algorithms and multimodal data integration.

Multimodal Monitoring in Large Hemispheric Infarction: Quantitative Electroencephalography Combined With Transcranial Doppler for Prognosis Prediction

Background: We aimed to explore whether transcranial Doppler (TCD) combined with quantitative electroencephalography (QEEG) can improve prognosis evaluation in patients with a large hemispheric infarction (LHI) and to establish an accurate prognosis prediction model.

Methods: We prospectively assessed 90-day mortality in patients with LHI. Brain function was monitored using TCD-QEEG at the bedside of the patient.

Results: Of the 59 (55.3 ± 10.6 years; 17 men) enrolled patients, 37 (67.3%) patients died within 90 days. The Cox regression analyses revealed that the Glasgow Coma Scale (GCS) score ≤ 8 [hazard ratio (HR), 3.228; 95% CI, 1.335–7.801; p = 0.009], TCD-terminal internal carotid artery as the offending vessel (HR, 3.830; 95% CI, 1.301–11.271; p = 0.015), and QEEG-a (delta + theta)/(alpha + beta) ratio ≥ 3 (HR, 3.647; 95% CI, 1.170–11.373; p = 0.026) independently predicted survival duration. Combining these three factors yielded an area under the receiver operating characteristic curve of 0.905 and had better predictive accuracy than those of individual variables (p < 0.05).

Conclusion: TCD and QEEG complement the GCS score to create a reliable multimodal method for monitoring prognosis in patients with LHI.

The within- and between-day reliability of cerebrovascular reactivity using traditional and novel analytical approaches

NEW FINDINGS

What is the central question of the study? What is the reliability of middle cerebral artery velocity cerebrovascular reactivity (CVR) when using traditional and novel outcomes, as measured by transcranial Doppler? What is the main finding and its importance? Traditional CVR approaches presented acceptable reproducibility but should be expressed as an absolute CVR. Large within- and between-individual differences in the middle cerebral artery velocity response profile support using a dynamic peak, rather than a set time point, for the most reliable interpretation. The study highlights the utility of novel kinetic CVR outcomes, but due to increased variability in time-based metrics, this analysis requires larger sample sizes than traditional methods.

ABSTRACT

Cerebrovascular reactivity (CVR) of middle cerebral artery velocity (MCAv) to CO₂ is a common method to assess cerebrovascular function. Yet, the approaches used to calculate CVR outcomes vary. The aim of this study was to explore the within- and between-day reliability of traditional CVR outcomes. The second aim was to explore the reliability of novel kinetic-based analyses. Healthy adults (n = 10, 22.3 ± 3.4 years) completed assessments of CVR over 4 min using a fixed fraction of inspired CO₂ (6%). This was repeated across four separate visits (between-day), and on one visit measures were repeated 2.5 h later (within-day). No mean biases were present between assessments for traditional CVR metrics, expressed as absolute (cm/s/mmHg) or relative (%/mmHg) outcomes (minute 3, minute 4, peak 1 s, peak 30 s) (between-day: P > 0.14, η_p ² < 0.20; within-day: P > 0.22, d > 0.27). Absolute, rather than relative, CVR yielded the most reproducible parameters (coefficient of variation: 8.1-13.2% vs. 14-83%, respectively). There were significant differences between CVR outcomes (P < 0.001, η_p ² > 0.89) dependent on the time point used to determine CVR, as a steady state MCAv response was rarely observed. Furthermore, the MCAv response was not reproducible within an individual (κ = 0.15, P = 0.09). No mean differences were present for novel kinetic outcomes (amplitude, time-delay, time constant) (between-day: P > 0.05, d < 0.33; within-day: P > 0.38, d < 0.25). The results support the need for standardisation and indicate CVR should be defined as a dynamic peak, rather than a set time point for increased reliability. For novel kinetic outcomes variability was greater (CV: 8.7-120.9%) due to the nature of time-based metrics.

Intracranial microembolic signals might be a potential risk factor for cognitive impairment

Objective: We aimed to explore the relationship between microembolic signals (MES) and cognitive impairment in patients with neurological disorders using a 30-minute MES monitoring test.Methods: We retrospectively reviewed patients who visited outpatient departments and underwent a 30-minute MES monitoring session using dual-channel transcranial doppler (TCD) at Beijing Tiantan hospital between July 2016 and December 2018. All patients completed the Montreal Cognitive Assessment (MoCA) and underwent magnetic resonance imaging (MRI). Cognitive impairment was defined as a MoCA score of less than 26. MES were identified according to the criteria of the International Consensus Group on Microembolus Detection.Results: Of the 1356 subjects who underwent MES monitoring, 159 patients (including 50 cases of MES positive and 109 cases of MES negative) had both analyzable MES monitoring recording and cognition evaluation data, of which 72 had cognitive impairment. Compared with the group with no deficits in cognitive function, the proportion of MES positive was significantly higher in patients with impaired cognitive function - that is, 47% (34/72) versus 18.4% (16/87), respectively, with p < 0.05. In multivariate logistic regression analysis, MES were independently associated with lower MoCA score (odd ratios (OR), 7.36; 95% confidence intervals (CI), 2.72-19.85, P < 0.0001).Conclusions: In this retrospective study, we found a possible correlation and relationship between MES and cognitive impairment. Further studies are required to determine whether continuous cerebral microembolization to the brain will lead to progressive cognitive impairment.

Utility of Transcranial Doppler in Moderate and Severe Traumatic Brain Injury: A Narrative Review of Cerebral Physiologic Metrics

Since its creation in the 1980s, transcranial Doppler (TCD) has provided a method of non-invasively monitoring cerebral physiology and has become an invaluable tool in neurocritical care. In this narrative review, we examine the role TCD has in the management of the moderate and severe traumatic brain injury (TBI) patient. We examine the principles of TCD and the ways in which it has been applied to gain insight into cerebral physiology following TBI, as well as explore the clinical evidence supporting these applications. Its usefulness as a tool to non-invasively determine intracranial pressure, detect post-traumatic vasospasm, predict patient outcome, and assess the state of cerebral autoregulation are all explored.

Transcranial Doppler Ultrasonography in Pre-hospital Management of Stroke: Can it make a Difference?

The aim of this paper is to discuss the use of transcranial doppler in the pre-hospital management of stroke. In the pre-hospital organization, neurological defect scales are used, but they are often indicative of the occlusions of anterior circulation and not of the posterior circulation. Patients with posterior circulation stroke are sometimes not diagnosed and clinically treated. In the pre-hospital phase, the transcranial doppler may identify an occlusion of the large cerebral vessels and be useful for stroke patients, in particular those with posterior occlusions, for a more precise diagnosis and consequently for adequate treatment in the excellence centers for stroke.

Neuromonitoring and Neurocognitive Outcomes in Cardiac Surgery: A Narrative Review

Neurocognitive dysfunction after cardiac surgery can present with diverse clinical phenotypes, which include postoperative delirium, postoperative cognitive dysfunction, and stroke, and it presents a significant healthcare burden for both patients and providers. Neurologic monitoring during cardiac surgery includes several modalities assessing cerebral perfusion and oxygenation (near-infrared spectroscopy, transcranial Doppler and jugular venous bulb saturation monitoring) and those that measure cerebral function (processed and unprocessed electroencephalogram), reflecting an absence of a single, definitive neuromonitor. This narrative review briefly describes the technologic basis of these neuromonitoring modalities, before exploring their use in clinical practice, both as tools to predict neurocognitive dysfunction, and with a bundle of interventions designed to optimize cerebral oxygen supply, with the aim of reducing postoperative delirium and cognitive dysfunction following cardiac surgery.

Multimodality Imaging in Acute Ischemic Stroke

Stroke is the most common cause of mortality and morbidity worldwide. The prognosis of stroke depends upon the area affected and its early treatment. Time is of the essence in the care of stroke patients as it is estimated that approximately 1.9 million neurons, 14 billion synapses, and 12 km myelinated nerve fibers are lost per minute. Therefore, early diagnosis and prompt treatment are necessary. The primary goal of imaging in acute stroke is to diagnose the underlying cause, estimate the area affected, predict response towards thrombolytic therapy and to exclude the conditions mimicking stroke. With advancements in radiology, multiple imaging modalities are available for diagnosis and predicting prognosis. None of them is considered alone to be perfect. In this era of multimodality imaging, the decision of choosing appropriate techniques depends upon purpose and availability. Non-Contrast Computed Tomography is time effective, and helps in excluding other causes, Trans Cranial Doppler is time-effective and cost-effective with wide availability, however, is operator dependent and less sensitive. It holds a great future in sonothrombolysis. Magnetic Resonance Imaging is so far considered to be the most superior one in terms of early diagnosis, planning for interventional treatment and predicting the response of treatment. However, it is limited due to high cost and lack of availability. The current review gives a detailed account of all imaging modalities available for imaging stroke and their associated pros and cons.

Ultrasound Diagnostic Method in Vascular Dementia: Current Concepts

BACKGROUND

Increasing interest in identifying cerebral hemodynamics alterations as a cause of possible onset or worsening of cognitive impairment in elderly patients with vascular risk factors.

INTRODUCTION

Intracranial ultrasound is a non-invasive, repeatable inexpensive method for recording variation of the cerebral vascular tree in physiological and pathological conditions and the diagnosis of vascular dementia (VaD).

METHODS

PubMed, Embase, Cochrane library and reference lists have been searched for articles published until March 30, 2020.

RESULTS

Clinical studies reported different Transcranial Doppler (TCD) parameters and subsequently transcranial duplex with color code (TCCD) in patients affected by vascular dementia. The number of studies using TCCD remains limited and most of the available data are still based on TCD. However, the use of transcranial Doppler could better stratify elderly patients with initial signs of cognitive impairment.

CONCLUSION

Intracranial ultrasound employment to detect cerebral hemodynamic changes in VaD patients has been briefly discussed in this review.

Cerebral Hemodynamic Evaluation of Main Cerebral Vessels in Epileptic Patients Based on Transcranial Doppler

Objective: To study whether there is a difference in peak and mean blood flow velocity between the left and right major cerebral vessels in patients with epilepsy.

Methods: Sixteen patients with epilepsy underwent FDG¹⁸-PET-CT (PET) scan and electroencephalogram (EEG) examinations. Transcranial Doppler (TCD) was used to detect the peak flow velocity (PFV), mean flow velocity (MFV), and other hemodynamic indicators of bilateral anterior, middle, and posterior cerebral arteries in each patient. According to different patterns of the PET or interictal EEG, the differences in PFV, and MFV of corresponding vessels on both sides under different patterns were compared.

Results: According to the PET of the low-metabolism region corresponding to the supplying artery, the PFV and MFV of the supplying artery in the low-metabolism region were lower than the value of the corresponding contralateral vessel. The PFV and MFV on the low metabolic side of PET were lower than that of the corresponding vessels on the opposite side. The PFV and MFV on the discharge side of interictal EEG were also lower than the PFV and MFV of the corresponding vessels on the opposite side. The MFV of posterior cerebral artery on the low metabolic side of PET or the interictal discharge side was significantly different from that of the contralateral vessels (P < 0.05). However, the other aforementioned differences in PFV and MFV did not achieve statistical significance.

Conclusion: In epileptic patients, the PFV and MFV of main cerebral vessels on the PET hypometabolized side or the interictal discharge side was lower than that of corresponding vessels on the contralateral side. To some extent, the difference in the MFV of PCA between the bilateral sides can facilitate the lateral diagnosis of the epileptogenic zone.

Transcranial Dopplers Revisited: Development of Novel Markers for Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage

Background

Cerebral vasospasm has been monitored by conventional angiography or transcranial Doppler (TCD). While angiography is the most accurate and reliable method for detection, TCDs are a noninvasive alternative to monitor onset and resolution of vasospasm. We aim to determine whether alternative TCD parameters rather than Lindegaard ratio lead to an improved method to diagnose and potentially prevent cerebral vasospasm.

Methods

A total of 103 consecutive patients with subarachnoid hemorrhage (SAH) were retrospectively reviewed and TCD studies were performed during the first 14 days post-bleed or longer if indicated. Multivariate logistic regression models were developed using significant univariate characteristics. Receiver operating characteristic (ROC) curves evaluated the mean middle cerebral artery (MCA), peak systolic MCA (PSV MCA), and end diastolic MCA (EDV MCA) velocities as well as ratios when compared to the ipsilateral extracranial internal carotid artery (ICA). The area under the curve was calculated to compare accuracy for symptomatic vasospasm.

Results

Thirteen patients (12.6%) were observed to develop cerebral vasospasm. Aneurysm location (p = 0.51), Hunt and Hess grade (p = 0.44), Fischer grade (p = 0.87), comorbidities, age (p = 0.67), or gender (p = 0.41) did not appear to have any effect in predicting the presence of vasospasm. ROC curves demonstrated that MCA EDV appeared to be slightly better compared to MCA velocity in predicting symptomatic vasospasm. PSV MCA/extracranial ICA and the EDV MCA/extracranial ICA ratios appeared to be an improvement to the Lindegaard ratio in the prediction of symptomatic vasospasm.

Conclusion

The utility of peak systolic and end diastolic velocities, instead of the classically referenced mean velocities and Lindegaard ratio, may improve diagnostic sensitivity of cerebral vasospasm after subarachnoid hemorrhage.

Psychopathological Symptom Load and Distinguishable Cerebral Blood Flow Velocity Patterns in Patients With Schizophrenia and Healthy Controls: A Functional Transcranial Doppler Study

Introduction: Schizophrenia is a severe psychiatric disorder, with executive dysfunction and impaired processing speed playing a pivotal role in the course of the disease. In patients with schizophrenia, neurocognitive deficits appear to be related to alterations in cerebral hemodynamics. It is not fully understood if psychopathological symptom load (i.e., presence and severity of symptoms) is also related to alterations in cerebral hemodynamics. We aim to study the relationship between psychopathological symptom load and cerebral hemodynamics in the Middle Cerebral Artery (MCA) during a cognitive task in patients with schizophrenia and healthy controls. Methodology: Cerebral hemodynamics in the MCA were examined in 30 patients with schizophrenia and 15 healthy controls using functional Transcranial Doppler (fTCD) during the Trail Making Test (TMT). Psychopathological symptoms were measured using the Brief Psychiatric Rating Scale (BPRS). Patients were dichotomized according to BPRS scores: mild-moderate (BPRS < 41, n = 15) or marked-severe (BPRS ≧ 41, n = 15). Mean blood flow velocity (MFV) in the MCA and processing speed of the TMT were analyzed. Cerebral hemodynamics were analyzed using the general additional model (GAM) with a covariate analysis of variance (ANCOVA) for group comparisons. Results: Patients and healthy controls were comparable regarding demographics. Patients had a slower processing speed for the TMT-A (patients-severe: 52s, patients-moderate: 40s, healthy-controls: 32s, p = 0.019) and TMT-B [patients-severe: 111s, patients-moderate: 76s, healthy-controls: 66s, p < 0.001)]. Patients demonstrated differing hemodynamic profiles in both TMTs: TMT- A [F _{(6, 1,792)} = 17, p < 0.000); TMT-B [F _{(6, 2,692)} = 61.93, p < 0.000], with a delay in increase in MFV and a failure to return to baseline values. Conclusions: Patients with schizophrenia demonstrated slower speeds of processing during both the TMT-A and TMT-B. The speed of processing deteriorated with increasing psychopathological symptom load, additionally a distinct cerebral hemodynamic pattern in the MCA was observed. Our results further support the view that severity of schizophrenia, particularly psychopathological symptom load, influences performance in neurocognitive tasks and is related to distinct patterns of brain hemodynamics.

Cerebral Blood Flow and Cognitive Performance in Postural Tachycardia Syndrome: Insights from Sustained Cognitive Stress Test

Background

The physiology underlying "brain fog" in the absence of orthostatic stress in postural tachycardia syndrome (POTS) remains poorly understood.

Methods and Results

We evaluated cognitive and hemodynamic responses (cardiovascular and cerebral: heart rate, blood pressure, end‐tidal carbon dioxide, and cerebral blood flow velocity (CBFv) in the middle cerebral artery at baseline, after initial cognitive testing, and after (30‐minutes duration) prolonged cognitive stress test (PCST) whilst seated; as well as after 5‐minute standing in consecutively enrolled participants with POTS (n=22) and healthy controls (n=18). Symptom severity was quantified with orthostatic hypotensive questionnaire at baseline and end of study. Subjects in POTS and control groups were frequency age‐ and sex‐matched (29±11 versus 28±13 years; 86 versus 72% women, respectively; both P≥0.4). The CBFv decreased in both groups (condition, P=0.04) following PCST, but a greater reduction in CBFv was observed in the POTS versus control group (−7.8% versus −1.8%; interaction, P=0.038). Notably, the reduced CBFv following PCST in the POTS group was similar to that seen during orthostatic stress (60.0±14.9 versus 60.4±14.8 cm/s). Further, PCST resulted in greater slowing in psychomotor speed (6.1% versus 1.4%, interaction, P=0.027) and a greater increase in symptom scores at study completion (interaction, P<0.001) in the patients with POTS, including increased difficulty with concentration. All other physiologic responses (blood pressure and end‐tidal carbon dioxide) did not differ between groups after PCST (all P>0.05).

Conclusions

Reduced CBFv and cognitive dysfunction were evident in patients with POTS following prolonged cognitive stress even in the absence of orthostatic stress.

Neuromonitoring during general anesthesia in non-neurologic surgery

Cerebral complications are common in perioperative settings even in non-neurosurgical procedures. These include postoperative cognitive dysfunction or delirium as well as cerebrovascular accidents. During surgery, it is essential to ensure an adequate degree of sedation and analgesia, and at the same time, to provide hemodynamic and respiratory stability in order to minimize neurological complications. In this context, the role of neuromonitoring in the operating room is gaining interest, even in the non-neurolosurgical population. The use of multimodal neuromonitoring can potentially reduce the occurrence of adverse effects during and after surgery, and optimize the administration of anesthetic drugs. In addition to the traditional focus on monitoring hemodynamic and respiratory systems during general anesthesia, the ability to constantly monitor the activity and maintenance of brain homeostasis, creating evidence-based protocols, should also become part of the standard of care: in this challenge, neuromonitoring comes to our aid. In this review, we aim to describe the role of the main types of noninvasive neuromonitoring such as those based on electroencephalography (EEG) waves (EEG, Entropy module, Bispectral Index, Narcotrend Monitor), near-infrared spectroscopy (NIRS) based on noninvasive measurement of cerebral regional oxygenation, and Transcranial Doppler used in the perioperative settings in non-neurosurgical intervention. We also describe the advantages, disadvantage, and limitation of each monitoring technique.

Cerebrovascular responses to graded exercise in young healthy males and females

Although systemic sex-specific differences in cardiovascular responses to exercise are well established, the comparison of sex-specific cerebrovascular responses to exercise has gone under-investigated especially, during high intensity exercise. Therefore, our purpose was to compare cerebrovascular responses in males and females throughout a graded exercise test (GXT). Twenty-six participants (13 Females and 13 Males, 24 ± 4 yrs.) completed a GXT on a recumbent cycle ergometer consisting of 3-min stages. Each sex completed 50W, 75W, 100W stages. Thereafter, power output increased 30W/stage for females and 40W/stage for males until participants were unable to maintain 60-80 RPM. The final stage completed by the participant was considered maximum workload(Wmax ). Respiratory gases (End-tidal CO2 , EtCO2 ), middle cerebral artery blood velocity (MCAv), heart rate (HR), non-invasive mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) were continuously recorded on a breath-by-breath or beat-by-beat basis. Cerebral perfusion pressure, CPP = MAP (0. 7,355 distance from heart-level to doppler probe) and cerebral vascular conductance index, CVCi = MCAv/CPP 100mmHg were calculated. The change from baseline (Δ) in MCAv was similar between the sexes during the GXT (p = .091, ωp2  = 0.05). However, ΔCPP (p < .001, ωp2  = 0.25) was greater in males at intensities ≥ 80% Wmax and ΔCVCi (p = .005, ωp2  = 0.15) was greater in females at 100% Wmax . Δ End-tidal CO2 (ΔEtCO2 ) was not different between the sexes during exercise (p = .606, ωp2  = -0.03). These data suggest there are sex-specific differences in cerebrovascular control, and these differences may only be identifiable at high and severe intensity exercise.

A Systematic Review and Meta-analysis of the Therapeutic Effect of Acupuncture on Migraine

Background: Migraine is an intractable headache disorder, manifesting as periodic attacks. It is highly burdensome for patients and society. Acupuncture treatment can be beneficial as a supplementary and preventive therapy for migraine.

Objectives: This systematic review and meta-analysis aimed to investigate the efficacy and safety of acupuncture for migraine, and to examine transcranial doppler changes after acupuncture.

Methods: Reports, conference, and academic papers published before March 15, 2019 in databases including PubMed, Cochrane library, Embase, China National Knowledge Infrastructure, WANFANG Database, Chinese journal of Science and Technology, and China Biomedical were searched. Randomized controlled trials (RCTs) involving acupuncture, sham acupuncture, and medication in migraine were included. The Cochrane Collaboration software, RevMan 5.3, was used for data processing and migration risk analysis.

Results: Twenty-eight RCTs were included. 15 RCTs included medication only, 10 RCTs included sham acupuncture only, and 3 RCTs included both. The study included 2874 patients, split into 3 groups: acupuncture treatment group (n = 1396), medication control group (n = 865), and sham acupuncture control group (n = 613). The results showed that treatment was more effective in the acupuncture group than in the sham acupuncture group (MD = 1.88, 95% CI [1.61, 2.20], P < 0.00001) and medication group (MD = 1.16, 95% CI [1.12, 1.21], P < 0.00001). Improvement in visual analog scale (VAS) score was greater in the acupuncture group than in the sham acupuncture group (MD = −1.00, 95% CI [-1.27,−0.46], P < 0.00001; MD = −0.59, 95% CI [-0.81,−0.38], P < 0.00001), and their adverse reaction rate was lower than that of the medication group (RR = 0.16, 95% CI [0.05, 0.52], P = 0.002). The improvement of intracranial blood flow velocity by acupuncture is better than that by medication, but the heterogeneity makes the result unreliable.

Conclusions: Acupuncture reduced the frequency of migraine attacks, lowered VAS scores, and increased therapeutic efficiency compared with sham acupuncture. Compared with medication, acupuncture showed higher effectiveness with less adverse reactions and improved intracranial blood circulation. However, owing to inter-study heterogeneity, a prospective, multicenter RCT with a large sample is required to verify these results.

Impact of hypotension on cerebral perfusion during general anesthesia induction: A prospective observational study in adults

INTRODUCTION

During anesthesia, decreases in mean arterial pressure (MAP) are common but the impact on possible cerebral hypoperfusion remains a matter of debate. We evaluated cerebral perfusion in patients with or without cardiovascular comorbidities (Hi-risk vs Lo-risk) during induction of general anesthesia and during hypotensive episodes.

METHODS

Patients scheduled for neuroradiology procedure using standardized target-controlled Propofol-Remifentanil infusion were prospectively included. Monitoring included Transcranial Doppler (TCD) measuring mean blood velocity of the middle cerebral artery (Vm), Bispectral Index with burst suppression ratio (SR) and cerebral Near-Infrared Spectroscopy (NIRS). Hypotensive episodes were treated with a 10 µg bolus of Norepinephrine.

RESULTS

Eighty-one patients were included, 37 Hi-risk and 44 Lo-risk. During induction of anesthesia, MAP and Vm decreased in all patients, with greater changes observed in Hi-risk patients compared to Lo-risk patients (-34 [38-29]% vs -17 [25-8]%, P < .001 and -39 [45-29]% vs -28 [34-19]%, P < .01 respectively). In Hi-risk patients, the MAP-decrease correlated with the Vm-decrease (r = .48, P < .01), and was associated with more frequent occurrences of SR (21 vs 5 patients, P < .01 for Hi-risk vs Lo-risk). For the MAP-increase induced by norepinephrine, the Vm-increase was greater in Hi-risk than in Lo-risk patients (+15 [8-21]% vs +4 [1-11]%, P < .01). During induction and norepinephrine boluses, NIRS values did not follow acute changes of Vm.

CONCLUSION

Our results showed that Hi-risk patients had a higher decrease in MAP and Vm, and a higher occurrence of SR during induction of anesthesia than Lo-risk patients. Correction of MAP with norepinephrine increased Vm mainly in Hi-rik patients.

The coexistence of a patent foramen ovale and obstructive sleep apnea may increase the risk of wake-up stroke in young adults

BACKGROUND:

Patent foramen ovale (PFO) and obstructive sleep apnea (OSA) are independent risk factors for young conscious stroke which may also be concomitant symptoms with it. But there is no sufficient attention on these phenomena.

OBJECTIVE:

To investigate the relationship between PFO, OSA and young stroke, and to look for proper treatment.

METHODS:

Three patients with young conscious stroke were reported, each of them was combined with PFO and OSA. All patients were diagnosed as wake-up stroke (WUS). Contrast-enhanced transcranial doppler ultrasound (c-TCD) and polysomnography (PSG) test were used for auxiliary diagnosis.

RESULTS:

Right-to-left shunts and moderate to severe sleep apnea were observed. Increased body mass index (BMI), hemoglobin (HGB) and hematocrit (HCT) index were also observed. After continuous positive airway pressure (CPAP) therapy, the number of microbubbles was reduced in one patient.

CONCLUSIONS:

These suggest that coexistence of PFO and OSA may associate with a greater risk of youth stroke. Decrease risk of stroke might occur if treating with CPAP in patients with OSA.

Cerebral Blood Flow in Low Intracranial Pressure Headaches-What is Known?

Headaches attributed to low cerebrospinal fluid (CSF) pressure are described as orthostatic headaches caused by spontaneous or secondary low CSF pressure or CSF leakages. Regardless of the cause, CFS leaks may lead to intracranial hypotension (IH) and influence cerebral blood flow (CBF). When CSF volume decreases, a compensative increase in intracranial blood volume and cerebral vasodilatation occurs. Sinking of the brain and traction on pain-sensitive structures are thought to be the causes of orthostatic headaches. Although there are many studies concerning CBF during intracranial hypertension, little is known about CBF characteristics during low intracranial pressure. The aim of this review is to examine the relationship between CBF, CSF, and intracranial pressure in headaches assigned to low CSF pressure.

Algorithm for Reliable Detection of Pulse Onsets in Cerebral Blood Flow Velocity Signals

Transcranial Doppler (TCD) ultrasound has been demonstrated to be a valuable tool for assessing cerebral hemodynamics via measurement of cerebral blood flow velocity (CBFV), with a number of established clinical indications. However, CBFV waveform analysis depends on reliable pulse onset detection, an inherently difficult task for CBFV signals acquired via TCD. We study the application of a new algorithm for CBFV pulse segmentation, which locates pulse onsets in a sequential manner using a moving difference filter and adaptive thresholding. The test data set used in this study consists of 92,012 annotated CBFV pulses, whose quality is representative of real world data. On this test set, the algorithm achieves a true positive rate of 99.998% (2 false negatives), positive predictive value of 99.998% (2 false positives), and mean temporal offset error of 6.10 ± 4.75 ms. We do note that in this context, the way in which true positives, false positives, and false negatives are defined caries some nuance, so care should be taken when drawing comparisons to other algorithms. Additionally, we find that 97.8% and 99.5% of onsets are detected within 10 and 30 ms, respectively, of the true onsets. The algorithm's performance in spite of the large degree of variation in signal quality and waveform morphology present in the test data suggests that it may serve as a valuable tool for the accurate and reliable identification of CBFV pulse onsets in neurocritical care settings.

Association Between Periodic Limb Movements in Sleep and Cerebrovascular Changes in Children With Sickle Cell Disease

STUDY OBJECTIVES

Periodic limb movements (PLMs) have been associated with increased risk of stroke, but there is currently scarce research exploring this relationship in the setting of sickle cell disease (SCD). The aim of this study was to explore whether increased PLMs in children with SCD are associated with increased risk of cerebrovascular disease and to determine if there are any clinical or laboratory differences between children with SCD with elevated periodic limb movement index (PLMI) versus those with normal PLMI.

METHODS

This study is a comprehensive review of medical records of 129 children with SCD (aged ≤ 18 years) who had undergone polysomnography for evaluation of sleep-disordered breathing.

RESULTS

Elevated PLMI (PLMI > 5 events/h) was present in 42% (54/129) of children with SCD. Children with elevated PLMI were found to have higher percentage of hemoglobin S, lower total iron, higher arousal index and tendency toward elevated transcranial Doppler velocity (P = .063, odds ratio = 3.9, 95% CI 0.93-16.22). While association between elevated PLMI and isolated cerebrovascular stenosis (P = .050, odds ratio 5.6, 95% CI 1.0-31.10) trended toward significance, there was significantly greater proportion of children with elevated PLMI who had cerebrovascular stenosis with Moyamoya disease (P = .046) as demonstrated by magnetic resonance imaging (MRI).

CONCLUSIONS

The prevalence of elevated PLMI in children with SCD was higher than in previously published data. Elevated PLMI was significantly associated with greater rates of cerebrovascular disease as detected by MRI.