Bilateral Middle Cerebral Artery Research Articles

Assessment of Dynamic Cerebral Autoregulation During Long-Term Exposure to High Altitude in Normal Subjects by Ultrasonography.

To evaluate changes in dynamic cerebral autoregulation (CA) during short-term and long-term exposure to high altitude with ultrasonography, and also study the sex differences in the response of CA to altitude. We assessed the differences in dynamic CA and measured with Doppler ultrasound of the bilateral internal carotid artery (ICA), vertebral artery (VA), and middle cerebral artery (MCA) and the values of basic information within 48 hours and at 2 years after arrival at Tibet in 65 healthy Han young Chinese volunteers, meanwhile, we compared the resistance index (RI) and pulsatility index (PI) of the right MCA at inhale oxygen 8 minutes when a newcomer with 2 years after arrival at Tibet. With 2 years of altitude exposure, the SaO2 of all subjects was above 90%, the mean PEF, DAP, and HR values decreased, HGB increased compared within 48 hours in same-gender groups. Comparisons of cerebral hemodynamics between before 2 years and after 2 years within male and female groups, the mean RI and PI values of bilateral MCA after 2 years were significantly higher than before 2 years, at the same time, the mean RI and PI values of bilateral ICA were significant differences (P < .05) between male groups, with regard to female groups, showed that the mean RI and PI values of bilateral VA were significant differences (P < .05). Comparisons of Right MCA hemodynamics between after oxygen uptake 8 minutes and 2 years, the mean RI and PI values were no significant difference within male and female groups (P > .05). Acute mountain sickness could result from an alteration of dynamic autoregulation of cerebral blood flow, but the impaired autoregulation may be corrected with the extension of time, furthermore, the response of CA to altitude in males and females are different.

REDUCED AEROBIC FITNESS IS ASSOCIATED WITH IMPAIRED CEREBROVASCULAR FUNCTION IN INDIVIDUALS WITH ATRIAL FIBRILLATION

INTRODUCTION &amp; AIMS Lower aerobic fitness (V̇O2peak) is associated with higher risk of cerebrovascular disease. However, the relationship between V̇O2peak and cerebrovascular function and cerebral blood velocity at rest and during exercise has not been investigated in adults with atrial fibrillation (AF). We aimed to compare resting and exercise cerebral blood velocity responses and cerebrovascular function in individuals with AF to healthy controls. METHODS Eight inactive adults either with AF or healthy age-matched controls (AF: n=4, 64±6 years, 50% female; control: n=4, 66±4 years, 75% female) completed a maximal graded exercise test to measure V̇O2peak. Transcranial Doppler was used to measure bilateral middle cerebral artery velocity (MCAv). Vascular function was assessed by measuring MCAv increases and time to peak following a 30s hypercapnia stimulus (9% CO2, 21% O2, and balanced nitrogen), and MCAv during aerobic exercise (3-minute stages at 40%, 60% and 80% V̇O2peak). Blood pressure, heart rate and end-tidal gases were collected alongside MCAv. RESULTS Compared to controls, individuals with AF (both P&amp;lt;0.01) had higher BMI (AF: 31.8±2.0 kg/m2; control: 27.3±0.6 kg/m2), lower V̇O2peak (AF: 19.9±2.5 mL/kg/min; control: 33.7±5.8 mL/kg/min), and similar blood pressure. Resting right and left MCAv was higher in the AF group (R: 66.6±34.0 cm/s; L: 44.2±10.1 cm/s) compared to the control (R: 36.1±6.7 cm/s; L: 34.9±8.7 cm/s); this was not significant (P=0.121 and 0.258). Right MCAv was higher than left MCAv in individuals with AF but this was not significant (P=0.247). Hypercapnia and exercise induced MCAv and time to peak were similar between groups (P&amp;gt;0.05). CONCLUSION Lower V̇O2peak may be associated with increased resting MCAv in individuals with AF. Furthermore, there may be regional disparities in MCAv in individuals with AF. Future studies with larger sample sizes investigating potential mechanisms and volumetric cerebrovascular changes (e.g., vessel diameter, arterial stiffness) in AF are warranted.

Moyamoya Syndrome in a Child with Beta-Thalassemia Trait: A Case Report with Review of Literature

Background: The association of moyamoya angiopathy with hematological conditions such as sickle cell anemia and beta-thalassemia major or intermedia is well-known, but moyamoya syndrome (MMS) associated with thalassemia trait is hardly reported. We report such a rare association. Clinical Description: A 7-year-old boy presented with right-sided monoparesis with right-sided focal seizures, along with right-sided upper motor neuron type facial nerve palsy. He had a history of recurrent transient episodes of limb weakness, which were unevaluated. Examination revealed pallor and mild splenomegaly. Management and Outcome: Routine investigations revealed microcytic hypochromic anemia with normal serum iron levels. High-performance liquid chromatography was suggestive of beta-thalassemia trait. Contrast-enhanced computerized tomography of the head showed infarction in the territory of the left anterior cerebral artery (ACA) and middle cerebral artery (MCA). Magnetic resonance angiography revealed significantly attenuated bilateral internal carotid arteries in the supraclinoid region with attenuated bilateral ACA and bilateral MCA along with collateral formation suggestive of moyamoya angiopathy. The final diagnosis of MMS secondary to beta-thalassemia trait was made. The child improved with aspirin and supportive management. Conclusion: MMS can be rarely associated with the beta-thalassemia trait. Such an underlying, unsuspected heterozygous beta-thalassemia (trait) may be diagnosed only after the identification of moyamoya disease following a stroke.

A Comparative Study of Transcranial Color-Coded Doppler (TCCD) and Transcranial Doppler (TCD) Ultrasonography Techniques in Assessing the Intracranial Cerebral Arteries Haemodynamics.

Cerebrovascular disease (CVD) poses a major public health and socio-economic burden worldwide due to its high morbidity and mortality rates. Accurate assessment of cerebral arteries' haemodynamic plays a crucial role in the diagnosis and treatment management of CVD. The study compared a non-imaging transcranial Doppler ultrasound (TCD) and transcranial color-coded Doppler ultrasound (with (cTCCD) and without (ncTCCD)) angle correction in quantifying middle cerebral arteries (MCAs) haemodynamic parameters. A cross-sectional study involving 50 healthy adults aged ≥ 18 years was conducted. The bilateral MCAs were insonated via three trans-temporal windows (TTWs-anterior, middle, and posterior) using TCD, cTCCD, and ncTCCD techniques. The MCA peak systolic velocity (PSV) and mean flow velocity (MFV) were recorded at proximal and distal imaging depths that could be visualised on TCCD with a detectable spectral waveform. A total of 152 measurements were recorded in 41 (82%) subjects with at least one-sided open TTW across the three techniques. The mean PSVs measured using TCD, ncTCCD, and cTCCD were 83 ± 18 cm/s, 81 ± 19 cm/s, and 93 ± 21 cm/s, respectively. There was no significant difference in PSV between TCD and ncTCCD (bias = 2 cm/s, p = 1.000), whereas cTCCD yielded a significantly higher PSV than TCD and ncTCCD (bias = -10 cm/s, p < 0.001; bias = -12 cm/s, p ≤ 0.001, respectively). The bias in MFV between TCD and ncTCCD techniques was (bias = -0.5 cm/s; p = 1.000), whereas cTCCD demonstrated a higher MFV compared to TCD and ncTCCD (bias = -8 cm/s, p < 0.001; bias = -8 cm/s, p ≤ 0.001, respectively). TCCD is a practically applicable imaging technique in assessing MCA blood flow velocities. cTCCD is more accurate and tends to give higher MCA blood flow velocities than non-imaging TCD and ncTCCD techniques. ncTCCD is comparable to non-imaging TCD and should be considered in clinical cases where using both TCD and TCCD measurements is needed.

Abstract WP194: Quantified Effects of Intra-Arterial Vasodilatory Therapy for Cerebral Vasospasm

Introduction: Cerebral vasospasm is a major cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). Though used routinely in clinical practice, objective metrics to evaluate effectiveness of intra-arterial vasodilatory treatment (IAT) have not been identified. To quantify effects of IAT on flow dynamics in cerebral vasospasm, we retrospectively compared Lindegaard ratios (LR) of aSAH patients pre-and post-IAT. Methods: Subjects included 24 aSAH patients undergoing IAT in the bilateral middle cerebral arteries (MCA) for cerebral vasospasm, diagnosed by standard clinical and radiographic criteria. Subjects were excluded if balloon angioplasty was performed prior to/within 2 days of the index procedure. All subjects received 10 mg IA milrinone, a non-catecholamine phosphodiesterase inhibitor drug, per MCA. Transcranial doppler (TCD) ultrasound was measured pre-IAT (D0) and at D+1 and D+2 post-IAT. LR was calculated as the ratio of mean flow velocities in the middle cerebral artery (MCA) to the ipsilateral extracranial internal carotid artery. Standard threshold for vasospasm is defined as LR&gt;3. Results: Right and left LR were aggregated, total N=48. Average pre-IAT LR was 2.96 (R 2.67/L 3.25±1.29). Post-IA LR were 2.72±1.12 and 3.15±1.55 at D+1 and D+2, respectively. Subjects with pre-IA LR&gt;3 showed an average LR decrease of 21% post-IAT D+1 (p=0.01) and an 8% decrease at D+2 (p=0.16) [Fig.1A]. Subjects with pre-IAT&lt;3 experienced an average LR increase of 28% by D+2 (p=0.02) [Fig 1B]. Conclusion: Subjects with TCD confirmed vasospasm (LR&gt;3) at D0 showed a significant improvement in cerebral blood flow one day after therapy. Subjects who did not meet TCD threshold for vasospasm (LR&lt;3) showed little change one day post-IAT but worsening cerebral blood flow by day two post-IAT. Further study is needed to determine whether LR can be used to predict benefit or objectively assess effectiveness of IAT in aSAH patients with cerebral vasospasm.

Abstract WP121: Cerebral Hemodynamics in the First Week Postpartum in Healthy Women and Women With Preeclampsia

Objective: Standard adult normative data for transcranial Doppler (TCD)-based cerebral hemodynamic measures, such as mean and peak cerebral blood flow velocity (mCBFV, pCBFV), are used to identify pathological conditions such as postpartum angiopathy. However, little is known about cerebral hemodynamics during the early postpartum period, particularly in patients with preeclampsia (PEC). We characterized cerebral hemodynamics using TCD in the first week postpartum in patients with and without PEC. Methods: We prospectively recruited women with PEC and normotensive pregnant women delivering at an urban academic medical center. We measured CBFV in the bilateral middle cerebral arteries with TCD and calculated systolic mCBFV and pCBFV as well as pulsatility index (PI) and PI-derived noninvasive intracranial pressure (nICP). We compared systolic mCBFV and pCBFV between postpartum women with and without PEC, and historical data from non-pregnant young adult female controls. Results: Subjects were 51 women with PEC, 19 normotensive postpartum women, and 28 non-pregnant historical controls. In the PEC group, median mCBFV was 75.0 cm/s (IQR 65.2-99.1) and median pCBFV was 106.9 cm/s (IQR 92.7-130.8). In the normotensive postpartum group, median mCBFV was 77.1 cm/s (IQR 66.0-92.3) and median pCBFV was 107.9 cm/s (IQR 96.6-127.4). In the non-pregnant female control group, median mCBFV was 62.0 cm/s (IQR 48.5-67.9) and median pCBFV was 83.6 cm/s (IQR 69.3-95.2) (p&lt;0.0001 for mean and peak 3-way comparisons; see Figure). PI and nICP were within normal range in both postpartum groups and did not differ significantly between groups. Conclusion: Postpartum women with and without PEC had mCBFV and pCBFV significantly higher than non-pregnant controls, and many fell outside the standard normal range for healthy adults, but PI and nICP were within normal range. Standard ranges of CBFV for healthy adults may not apply in the postpartum period.

Depression of dynamic cerebral autoregulation during neural activation: The role of responders and non-responders.

Neurovascular coupling (NVC) interaction with dynamic cerebral autoregulation (dCA) remains unclear. We investigated the effect of task complexity and duration on the interaction with dCA. Sixteen healthy participants (31.6 ± 11.6 years) performed verbal fluency (naming-words (NW)) and serial subtraction (SS) paradigms, of varying complexity, at durations of 05, 30 and 60 s. The autoregulation index (ARI), was estimated from the bilateral middle cerebral artery blood velocity (MCAv) step response, calculated by transfer function analysis (TFA), for each paradigm during unstimulated (2 min) and neuroactivated (1 min) segments. Intraclass correlation (ICC) and coefficient of variation (CV) determined reproducibility for two visits and objective criteria were applied to classify responders (R) and non-responders (NoR) to task-induced MCAv increase. ICC values demonstrated fair reproducibility in all tasks. ARI decreased in right (RH) and left (LH) hemispheres, irrespective of paradigm complexity and duration (p < 0.0001). Bilateral ARI estimates were significantly decreased during NW for the R group only (p < 0.0001) but were reduced in both R (p < 0.0001) and NoR (p = 0.03) groups for SS tasks compared with baseline. The reproducible attenuation of dCA efficiency due to paradigm-induced NVC response, its interaction, and different behaviour in R and NoR, warrant further research in different physiological and clinical conditions.

Acute bilateral middle cerebral artery occlusion treated with thrombectomy via the anterior communicating artery in a patient with chronic left cervical internal carotid artery occlusion: a case report

Acute bilateral middle cerebral artery occlusion treated with thrombectomy via the anterior communicating artery in a patient with chronic left cervical internal carotid artery occlusion: a case report

Exploring Cerebral Perfusion Transcranial Doppler Parameters in Patients Admitted to Combined Medical Surgical Intensive Care Unit

Introduction: Encephalopathy, a common complication in Intensive Care Unit (ICU) patients, is often linked to poor outcomes. Transcranial Doppler (TCD), a non-invasive tool assesses cerebral perfusion via the Pulsatility Index (PI), Resistivity Index (RI), and Time-Averaged Peak (TAP) or Mean Flow Velocity (MFV). These parameters may offer insights into cerebral perfusion and outcomes in encephalopathic patients. Aim: To describe the PI, RI of the Middle Cerebral Artery (MCA), and MFV or TAP measured by TCD in patients admitted to the ICU, comparing those with and without encephalopathy at the time of admission. Materials And Methods: This cross-sectional observational study was conducted from January 2019 to November 2020, in a combined medical-surgical ICU of a tertiary care hospital, involving 45 enrolled patients. Patients were evaluated within 24 hours of admission and subsequently every 24 hours until ICU discharge, death, or discharge against medical advice. Bilateral Middle cerebral artery TCD studies were conducted using a 1-5 MHz phased array probe or TCD mode through the transtemporal window. The PI, RI, and MFV were measured on both sides, with the higher value used for analysis, and all statistical analyses were performed using Statistics and Data 13 software. Results: In the present study, 88% (n=40) of patients had encephalopathy (GCS&lt;15 and RAAS less than or more than 0). The mean APACHE II score was 19 (14-25), indicating severe illness with a predicted mortality of 30-40%. Patients with encephalopathy had significantly higher APACHE II scores compared to those without (19.5 (16-25) vs 10 (4-19)). Although there was a trend towards a higher Pulsatility Index in encephalopathic patients at admission (1.11±0.378 vs 1.07±0.12, p=0.81), PI, RI, and TAP values did not significantly differ in non-survivors (1.12±0.49 vs 1.11±0.33, p=0.750). Persistent encephalopathy was associated with a trend towards higher PI at admission (1.05±0.24 vs 1.16±0.46; p=0.756), and a moderate correlation was found between decreasing PI and improvement in GCS (rho=-0.489, p=0.001). Conclusions: PI, RI, and TAP at the time of admission were not found to be associated with occurrence and recovery of encephalopathy as well as mortality. The trend of change in PI moderately correlated with improvement in GCS suggesting the importance of trends rather than absolute values.

Lateral medullary infarction in a patient with Moyamoya disease associated with RNF213 variants: a case report

Background: Moyamoya disease (MMD) is a rare cerebrovascular disease radiologically characterized by progressive bilateral occlusion of the distal portion of the internal carotid artery and compensating collaterals. Herein, we report a case of medullary infarction in a patient with MMD.Case Report: We present the case of a 54-year-old male with hypertension, hyperlipidemia, and unstable angina with sudden onset dysarthria and ataxia. Diffusion-weighted and T2-weighted images of magnetic resonance imaging showed a high-signal intensity lesion on the right lateral medulla, suggestive of acute infarction. Transfemoral cerebral angiography also demonstrated bilateral middle cerebral artery (MCA) occlusion. Testing of the ring finger protein 213 (RNF213) gene revealed a homozygous p.R4810K variant that was possibly associated with posterior circulation involvement.Conclusion: When the MCA is occluded in MMD, there is a possibility that medullary infarction may occur due to the mechanism of increased hemodynamic stress on the anastomotic posterior vessels.

Improving the impact of different input arteries on cerebral CT perfusion parameters and ischemic penumbra

This study aims to examine the impact of different input arteries on cerebral perfusion parameters and the volume of core infarction, ischemic area, and penumbra automatically measured by software in post-processing 256-slice CT brain perfusion images. Retrospective analysis was conducted on brain perfusion images of 58 patients who underwent 256-slice multidetector CT examination for cerebral infarction. Various input arteries, including bilateral internal carotid artery (ICA), bilateral middle cerebral artery (MCA), anterior cerebral artery (ACA), and basilar artery (BA), were selected for image processing and measurements. The volumes of core infarction, ischemic area, and penumbra were automatically calculated using software. Additionally, manual measurements were per-formed by experienced doctors. Perfusion parameters including cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time to peak (TTP) were evaluated. The change of input artery resulted in a significant difference in CBF and MTT in the penumbra and normal brain tissue areas. However, no significant difference was observed in CBV, TTP, and perfusion parameters in the core infarct area. The volumes of core infarction acquired from different input arteries showed no significant difference. Nonetheless, significant differences were found in the volume of the ischemic area and the mismatched area. The selection of different input arteries affects CT cerebral perfusion parameter values and the automatic measurement of the ischemic area and penumbra by software. Thus, when performing post-processing of CT cerebral perfusion images, it is advisable to choose the thicker internal carotid artery on the healthy side as the input artery.

Cerebral blood flow and neurocognition in patients undergoing transcatheter aortic valve replacement for severe aortic stenosis.

Aortic valve stenosis (AS) results in higher systolic pressure to overcome resistance from the stenotic valve, leading to heart failure and decline in cardiac output. There has been no assessment of cerebral blood flow (CBF) association with neurocognition in AS or the effects of valve replacement. The goal was to determine if AS is associated with altered cerebral haemodynamics and impaired neurocognition, and whether transcatheter aortic valve replacement (TAVR) improves haemodynamics and cognition. In 42 patients with planned TAVR, transcranial Doppler (TCD) assessed bilateral middle cerebral artery (MCA) mean flow velocities (MFVs); abnormality was <34.45 cm/s. The neurocognitive battery assessed memory, language, attention, visual-spatial skills, and executive function, yielding a composite Z-score. Impairment was <1.5 SDs below the normative mean. The mean age was 78 years, 59% Male, and the mean valve gradient was 46.87 mm/Hg. Mean follow-up was 36 days post-TAVR (range 27-55). Pre-TAVR, the mean MFV was 42.36 cm/s (SD = 10.17), and the mean cognitive Z-score was -0.22 SDs (range -1.99 to 1.08) below the normative mean. Among the 34 patients who returned after TAVR, the MFV was 41.59 cm/s (SD = 10.42), not different from baseline (P = 0.66, 2.28-3.67). Post-TAVR, average Z-scores were 0.17 SDs above the normative mean, not meeting the pre-specified threshold for a clinically significant 0.5 SD change. Among patients with severe AS, there was little impairment of MFV on TCD and no correlation with cognition. Transcatheter aortic valve replacement did not affect MFV or cognition. Assumptions about diminished CBF and improvement after TAVR were not supported.

P103: Middle Cerebral Artery Stenosis is Associated with Severity of Depression in Elderly Patients: Magnetic Resonance Angiography (MRA) Findings

Objective:Vascular abnormalities have been frequently reported in elderly adults as a potential risk factor of late-life depression. However, it is still unclear whether stenosis of cerebral arteries may increase risk of depression in the elderly.Methods:Study participants were 365 patients 65 years or older with depressive disorder who had undergone brain MRI and angiography (MRA) which were assessed by trained radiologists, and the 15-item Geriatric Depression Scale (GDS-15) and the Mini Mental State Examination (MMSE), and blood glucose and lipid profiles.Results:Of the 365 subjects, 108 had at least one location of cerebral artery stenosis (29.59%). Stenosis was associated with age, marital status, infarction, and atherosclerosis. In multivariable linear regression analysis of different locations of stenosis among the whole sample, only bilateral middle cerebral artery (MCA) stenosis was found to have a significant association with higher GDS-15 score (p= 0.0138), and more than 8 scores in the GDS-15 (p= 0.0045), but no significant associations with ACA (anterior cerebral artery), PCA (posterior cerebral artery) or ICA (internal carotid artery). In multivariable linear logistic analysis of different locations among patients with at least one cerebral artery stenosis, left MCA was found to be significantly related to higher GDS-15 scores but not with right MCA (p = 0.0202).Conclusion:MCA stenosis is significantly associated with severity of depression in elderly adults with cerebral artery stenosis, especially in those with left MCA stenosis.Key pointsPatients with cerebral artery stenosis found with brain magnetic resonance angiography (MRA) were associated with higher depression severity.Stenosis of both left and right middle cerebral artery (MCA) was associated with greater depression severity, with left MCA stenosis having a greater influence on depression severity than right MCA stenosis.Higher depression severity in patients with MCA stenosis suggests that depression in elderly patients is mediated at least in part by vascular pathology of MCA supplied regions and careful investigation and management of cerebral artery stenosis and their risk factors may help reduce the severity of depression in elderly patients who visit psychiatrists.

Abstract 020: Undulating Flow Velocities as an Induced Test of Autoregulation After Thrombectomy for Acute Ischemic Stroke

Introduction Loss of autoregulation after endovascular therapy (EVT) for large‐artery acute ischemic stroke (AIS) is well documented. [1] This might result in worse outcomes, despite successful recanalization, from hyper‐ or hypoperfusion with a risk for hemorrhagic conversion or larger stroke volume, respectively. Transcranial doppler (TCD) was previously used to document this phenomenon using spontaneous fluctuations in reactivity. Herein, we present a patient with suspected obstructive sleep apnea (OSA) with undulating flow velocities on TCD, serving as a test for induced vasoreactivity with pre‐ and post‐EVT TCD. Methods A case‐report. Results A middle‐aged patient was admitted with acute left cerebellar stroke (figure 1A). An Embolic etiology was suspected and a 20‐minuteTCD was done for spontaneous emboli detection on bilateral middle cerebral arteries (MCA). The patient fell asleep during the study and it incidentally revealed a bilaterally symmetric undulating velocity, which is a pattern that was previously described with OSA as a result of vasomotor response to multiple apnea and hypopnea episodes occurring in succession (Figure 1D – Pre‐EVT). [2] This pattern indicates intact vasomotor reactivity to fluctuating O2 and CO2 levels during episodes of apnea. Six days later, the patient developed acute right MCA stroke (Figure 1B) and was treated with EVT with successful reperfusion (TICI 2B67) (Figure 1C). TCD was repeated after EVT, and the previously seen undulating pattern was lost with significantly reduced variability on the right MCA compared to the contralateral side (figure 1E – Post‐EVT). This indicates a significant reduction in vasomotor reactivity and autoregulatory capacity of the right MCA. Follow up imaging revealed hemorrhagic conversion in the bed of the stroke with intraparenchymal bleeding (PH1) (Figures 1F‐H). This case is unique since it provides an induced test of autoregulation and compares pre‐ and post‐EVT autoregulatory function. Prior reports did not use any stressors to test for autoregulation. While in this case, apnea served as a natural test for autoregulation allowing for easier detection. This can serve as a future marker that can be easily quantified and might guide post‐EVT care. Using breath holding maneuvers or medication (e.g., Acetazolamide) might be considered in the future to quantify the autoregulatory response. Further studies are required to investigate the utility of induced, instead of spontaneous, autoregulation assessment post‐EVT to guide blood pressure goals and the duration of strict blood pressure control after endovascular intervention. Conclusion Induced tests for autoregulation using TCD might be feasible and should be considered in the future as an easy method for quantifying autoregulation post‐EVT. Further studies are required to clarify the utility of this biomarker in guiding post‐EVT care.

Influence of sex on the reliability of cerebral blood velocity regulation during lower body negative pressure and supine cycling with considerations of the menstrual cycle

Objective. To evaluate sex differences in the reliability of absolute and relative cerebral blood velocity (CBv) during concurrent supine cycling with lower body negative pressure (LBNP). Approach. A total of 19 participants (11 females; aged 20–33 years) completed five testing sessions, occurring on 7 d intervals. Visit 1 was a maximal-ramp-cycle test to ascertain peak CBv wattage. During visits 2–5, supine cycling protocol occurred at individualized peak CBv wattages with progressive decreases in LBNP from 0 to −20, −40, −60, −70, and −80 Torr. Menstrual cycle day was self-reported via the Rhinessa Women’s Questionnaire. Transcranial Doppler ultrasound insonated bilateral middle cerebral artery velocity (MCAv). Two-way ANOVA assessed potential day- and sex-differences at each LBNP stage. Reliability was determined using intraclass correlation coefficients (ICC) and coefficient of variation (CoV). Main results. For all physiological measures, no main-effects were present for day- or interaction-terms (p > 0.067; negligible-to-small effect sizes), while sex differences were noted for MCAv, blood pressure, and heart rate (p < 0.046). Across visits, males and females displayed excellent and good-to-excellent levels of reliability for MCAv metrics, respectively (ICC range: 0.745–0.999; CoV range: 0.33%–9.90%). Significance. During the current investigation, both relative and absolute CBv demonstrated high reliability in both male and female participants during a supine LBNP cycling protocol. An exploratory analysis revealed increased variance was found in female participants dependent on contraceptive use. Despite this, results indicate future LBNP studies may include females at any menstrual cycle stage.

Abstract 147: Utilization and Application of Transcranial Doppler Emboli Monitoring for Infective Endocarditis

Introduction The rapid growth of the elderly population, an increase in cardiac disease, and notable use of intracardiac prosthetic devices has led to an increased prevalence of infective endocarditis (IE). Among the sequelae observed with an IE diagnosis, acute ischemic stroke (AIS), subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), vasculitis, septic emboli, cerebral abscess, and infectious intracranial aneurysms (IIA) continue to complicate overall management of this disease. Current literature on neurological complications of IE includes limited data on the defined role of neuroimaging in dictating inpatient management. Transcranial doppler (TCD) emboli monitoring with high intensity signals (HITS) offers a real time, radiation‐free, relatively low cost, non‐invasive imaging option to potentially risk stratify and identify candidates for earlier intervention to prevent further cerebrovascular (CV) complications. Methods We conducted an observational study of infective endocarditis cases admitted to our institution from April 2022 to May 2023 who had TCD with HITS completed. Baseline clinical characteristics (age, sex, date and timing of TCD with HITS study, date of last positive blood culture, organism of infection, other neuroimaging utilized) were recorded. Observations recorded included the results of the TCD with HITS studies, the overall incidence and timing of neurological complications (AIS, SAH, ICH, IIA, septic emboli, cerebral abscess), timing of valve surgery, and inpatient mortality rates. A positive HITS was defined as detection of cerebral microembolism during ultrasound monitoring of bilateral middle cerebral arteries (MCA) for 30 minutes using a TCD machine (VIASONIX Dolphin IQ). Results Between April 2022 to July 2023, we identified 22 patients with confirmed left‐sided infective endocarditis who underwent TCD with HITS. Mean age was 66 years (SD, 10), and 82% were men. Leading pathogen types were Enterococcus Faecalis (27%) and Staphylococcus Epidermidis (18%). CV complications were noted in 19/22 patients (86%), the most common being AIS (82%) and IPH (18%). Two patients (9%) were found to have a positive HITS study, both of which developed septic emboli that caused ischemic stroke in one case, and hemorrhagic stroke in the other case. Average days from admission to timing of TCD with HITS study was 8.5 days. 14/22 patients underwent valve surgery (64%) during the admission on average 9.2 days after TCD with HITS study in the negative HITS group versus 5 days in the positive HITS group. Of the positive HITS cases, one of them died inpatient. Conclusion The association between neurological complications in patients with IE and cerebral microemboli detected with TCD monitoring has yet to be elucidated. While our observational study was limited by our sample size, both of our IE patients who had positive TCD with HITS studies developed more severe CV complications, and aggressive care was sought out more urgently to further minimize complications. Future directions include pursuing a prospective study incorporating TCD with HITS monitoring for patients with IE in order to risk‐stratify neurological complications and safety of valve surgery.

A case report of reversible cerebral vasoconstriction syndrome with thunderclap headache significantly exacerbated in the supine position and alleviated in the standing position

BackgroundReversible cerebral vasoconstriction syndrome (RCVS) is characterized by sudden onset thunderclap headache and multiple segmental reversible cerebral vasoconstrictions that improve within 3 months. The postpartum period is a well-known precipitating factor for the onset of RCVS. Cerebral venous thrombosis (CVT) causes thunderclap headaches in the postpartum period. While headache in CVT is sometimes exacerbated in the supine position, the severity of the headache in RCVS is usually independent of body position. In this study, we report a case of RCVS with thunderclap headache exacerbated in the supine position, and headache attacks that resolved quickly in the standing position during the postpartum period.Case presentationA 33-year-old woman presented with a sudden increase in blood pressure and thunderclap headache on the fifth postpartum day (day 1: the first sick day). The headache was severe and pulsatile, with onset in the supine position in bed, and peaked at approximately 10 s. It was accompanied by nausea and chills but there were no scintillating scotomas or ophthalmic symptoms. The headache resolved in the standing or sitting position but was exacerbated and became unbearable within a few seconds when the patient was in the supine position. Therefore, she was unable to lie supine at night. Computed tomography angiography (CTA) of the head on day 2 and magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) on day 3 showed no abnormalities. However, considering the possibility of RCVS, verapamil was initiated on day 3. The headache resolved the following day. MRA of the head on day 10 revealed diffuse and segmental stenoses in the bilateral middle and posterior cerebral arteries and basilar artery. Therefore, the patient was diagnosed with RCVS. The headache gradually resolved and disappeared completely on day 42. Cerebral vasoconstriction was also improved on MRA on day 43.ConclusionsThis postpartum RCVS case was notable for the exacerbation of headaches in the supine position. For the diagnosis of thunderclap headache in the postpartum period, RCVS should be considered in addition to CVT when the patient presents with a headache that is exacerbated in the supine position.

Neurophysiologic Features Reflecting Brain Injury During Pediatric ECMO Support

BackgroundExtracorporeal membrane oxygenation (ECMO) provides lifesaving support to critically ill patients who experience refractory cardiopulmonary failure but carries a high risk for acute brain injury. We aimed to identify characteristics reflecting acute brain injury in children requiring ECMO support.MethodsThis is a prospective observational study from 2019 to 2022 of pediatric ECMO patients undergoing neuromonitoring, including continuous electroencephalography, cerebral oximetry, and transcranial Doppler ultrasound (TCD). The primary outcome was acute brain injury. Clinical and neuromonitoring characteristics were collected. Multivariate logistic regression was implemented to model odds ratios (ORs) and identify the combined characteristics that best discriminate risk of acute brain injury using the area under the receiver operating characteristic curve.ResultsSeventy-five pediatric patients requiring ECMO support were enrolled in this study, and 62 underwent neuroimaging or autopsy evaluations. Of these 62 patients, 19 experienced acute brain injury (30.6%), including seven (36.8%) with arterial ischemic stroke, four (21.1%) with hemorrhagic stroke, seven with hypoxic-ischemic brain injury (36.8%), and one (5.3%) with both arterial ischemic stroke and hypoxic-ischemic brain injury. A univariate analysis demonstrated acute brain injury to be associated with maximum hourly seizure burden (p = 0.021), electroencephalographic suppression percentage (p = 0.022), increased interhemispheric differences in electroencephalographic total power (p = 0.023) and amplitude (p = 0.017), and increased differences in TCD Thrombolysis in Brain Ischemia (TIBI) scores between bilateral middle cerebral arteries (p = 0.023). Best subset model selection identified increased seizure burden (OR = 2.07, partial R2 = 0.48, p = 0.013), increased quantitative electroencephalographic interhemispheric amplitude differences (OR = 2.41, partial R2 = 0.48, p = 0.013), and increased interhemispheric TCD TIBI score differences (OR = 4.66, partial R2 = 0.49, p = 0.006) to be independently associated with acute brain injury (area under the receiver operating characteristic curve = 0.92).ConclusionsIncreased seizure burden and increased interhemispheric differences in both quantitative electroencephalographic amplitude and TCD MCA TIBI scores are independently associated with acute brain injury in children undergoing ECMO support.

Transcranial Color-Coded Sonography With Angle Correction As a Screening Tool for Raised Intracranial Pressure.

Transcranial Doppler (TCD) has been evaluated as a noninvasive intracranial pressure (ICP) assessment tool. Correction for insonation angle, a potential source of error, with transcranial color-coded sonography (TCCS) has not previously been reported while evaluating ICP with TCD. Our objective was to study the accuracy of TCCS for detection of ICP elevation, with and without the use of angle correction. Prospective study of diagnostic accuracy. Academic neurocritical care unit. Consecutive adults with invasive ICP monitors. Ultrasound assessment with TCCS. End-diastolic velocity (EDV), time-averaged peak velocity (TAPV), and pulsatility index (PI) were measured in the bilateral middle cerebral arteries with and without angle correction. Concomitant mean arterial pressure (MAP) and ICP were recorded. Estimated cerebral perfusion pressure (CPP) was calculated as estimated CPP (CPPe) = MAP × (EDV/TAPV) + 14, and estimated ICP (ICPe) = MAP-CPPe. Sixty patients were enrolled and 55 underwent TCCS. Receiver operating characteristic curve analysis of ICPe for detection of invasive ICP greater than 22 mm Hg revealed area under the curve (AUC) 0.51 (0.37-0.64) without angle correction and 0.73 (0.58-0.84) with angle correction. The optimal threshold without angle correction was ICPe greater than 18 mm Hg with sensitivity 71% (29-96%) and specificity 28% (16-43%). With angle correction, the optimal threshold was ICPe greater than 21 mm Hg with sensitivity 100% (54-100%) and specificity 30% (17-46%). The AUC for PI was 0.61 (0.47-0.74) without angle correction and 0.70 (0.55-0.92) with angle correction. Angle correction improved the accuracy of TCCS for detection of elevated ICP. Sensitivity was high, as appropriate for a screening tool, but specificity remained low.

Asymmetrically Dilated Perivascular Space and Impaired Perfusion in Bilateral Middle Cerebral Artery Occlusion.

Asymmetrically Dilated Perivascular Space and Impaired Perfusion in Bilateral Middle Cerebral Artery Occlusion.