Intracranial Pressure and Cerebral Hemodynamics in Infants Before and After Glenn Procedure.

OBJECTIVES: This prospective cohort study aimed to investigate changes in intracranial pressure (ICP) and cerebral hemodynamics in infants with congenital heart disease undergoing the Glenn procedure, focusing on the relationship between superior vena cava pressure and estimated ICP. DESIGN: A single-center prospective cohort study. SETTING: The study was conducted in a cardiac center over 4 years (2019-2022). PATIENTS: Twenty-seven infants with congenital heart disease scheduled for the Glenn procedure were included in the study, and detailed patient demographics and primary diagnoses were recorded. INTERVENTIONS: Transcranial Doppler (TCD) ultrasound examinations were performed at three time points: baseline (preoperatively), postoperative while ventilated (within 24-48 hr), and at discharge. TCD parameters, blood pressure, and pulmonary artery pressure were measured. MEASUREMENTS AND MAIN RESULTS: TCD parameters included systolic flow velocity, diastolic flow velocity (dFV), mean flow velocity (mFV), pulsatility index (PI), and resistance index. Estimated ICP and cerebral perfusion pressure (CPP) were calculated using established formulas. There was a significant postoperative increase in estimated ICP from 11 mm Hg (interquartile range [IQR], 10-16 mm Hg) to 15 mm Hg (IQR, 12-21 mm Hg) postoperatively (p = 0.002) with a trend toward higher CPP from 22 mm Hg (IQR, 14-30 mm Hg) to 28 mm Hg (IQR, 22-38 mm Hg) postoperatively (p = 0.1). TCD indices reflected alterations in cerebral hemodynamics, including decreased dFV and mFV and increased PI. Intracranial hemodynamics while on positive airway pressure and after extubation were similar. CONCLUSIONS: Glenn procedure substantially increases estimated ICP while showing a trend toward higher CPP. These findings underscore the intricate interaction between venous pressure and cerebral hemodynamics in infants undergoing the Glenn procedure. They also highlight the remarkable complexity of cerebrovascular autoregulation in maintaining stable brain perfusion under these circumstances.

Imaging and blood flow characteristics of cerebrovascular fenestration malformation and its relationship with the occurrence of ischemic cerebrovascular disease.

OBJECTIVE: To explore the imaging and transcranial Doppler cerebral blood flow characteristics of cerebrovascular fenestration malformation and its relationship with the occurrence of ischemic cerebrovascular disease. METHODS: A retrospective analysis was conducted on the imaging data of 194 patients with cerebrovascular fenestration malformation who visited the Heyuan People's Hospital from July 2021 to July 2023. The location and morphology of the fenestration malformation blood vessels as well as the presence of other cerebrovascular diseases were analyzed. Transcranial Doppler cerebral blood flow detection data of patients with cerebral infarction and those with basilar artery fenestration malformation were also analyzed. RESULTS: A total of 194 patients with cerebral vascular fenestration malformation were found. Among the artery fenestration malformation, basilar artery fenestration was the most common, accounting for 46.08% (94/194). 61 patients (31.44%) had other vascular malformations, 97 patients (50%) had cerebral infarction, of which 30 were cerebral infarction in the fenestrated artery supply area. 28 patients with cerebral infarction in the fenestrated artery supply area received standardized antiplatelet, lipid-lowering and plaque-stabilizing medication treatment. During the follow-up period, these patients did not experience any symptoms of cerebral infarction or transient ischemic attack again. There were no differences in peak systolic flow velocity and end diastolic flow velocity, pulsatility index and resistance index between the ischemic stroke group and the no ischemic stroke group in patients with basal artery fenestration malformation (P > 0.05). CONCLUSION: Cerebrovascular fenestration malformation is most common in the basilar artery. Cerebrovascular fenestration malformation may also be associated with other cerebrovascular malformations. Standardized antiplatelet and statin lipid-lowering and plaque-stabilizing drugs are suitable for patients with cerebral infarction complicated with fenestration malformation. The relationship between cerebral blood flow changes in basilar artery fenestration malformation and the occurrence of ischemic stroke may not be significant.

Transcranial volumetric imaging using a conformal ultrasound patch.

Accurate and continuous monitoring of cerebral blood flow is valuable for clinical neurocritical care and fundamental neurovascular research. Transcranial Doppler (TCD) ultrasonography is a widely used non-invasive method for evaluating cerebral blood flow1, but the conventional rigid design severely limits the measurement accuracy of the complex three-dimensional (3D) vascular networks and the practicality for prolonged recording2. Here we report a conformal ultrasound patch for hands-free volumetric imaging and continuous monitoring of cerebral blood flow. The 2 MHz ultrasound waves reduce the attenuation and phase aberration caused by the skull, and the copper mesh shielding layer provides conformal contact to the skin while improving the signal-to-noise ratio by 5 dB. Ultrafast ultrasound imaging based on diverging waves can accurately render the circle of Willis in 3D and minimize human errors during examinations. Focused ultrasound waves allow the recording of blood flow spectra at selected locations continuously. The high accuracy of the conformal ultrasound patch was confirmed in comparison with a conventional TCD probe on 36 participants, showing a mean difference and standard deviation of difference as -1.51 ± 4.34 cm s-1, -0.84 ± 3.06 cm s-1 and -0.50 ± 2.55 cm s-1 for peak systolic velocity, mean flow velocity, and end diastolic velocity, respectively. The measurement success rate was 70.6%, compared with 75.3% for a conventional TCD probe. Furthermore, we demonstrate continuous blood flow spectra during different interventions and identify cascades of intracranial B waves during drowsiness within 4 h of recording.

Orbital doppler ultrasound as an ancillary test for diagnosing brain death: A prospective, single blind comparative study.

OBJECTIVE: Transcranial Doppler ultrasound (TDUS), computed tomography angiography (CTA), and transcranial Doppler ultrasound to detect cerebral blood flow are among the adjunctive tests in diagnosing brain death. This study aimed to investigate the effectiveness of orbital doppler ultrasound (ODUS). METHODS: This prospective, single-blind study included 66 patients for whom brain death was to be diagnosed. Primary outcome measures were ODUS measurements, Ophthalmic artery peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive indices (RI) measurements recorded during the brain death determination process. Secondary outcome measures were computed tomography angio (CTA), transcranial Doppler ultrasound (TDUS), and demographic data. RESULTS: This study investigating the effectiveness of ODUS in diagnosing brain death provided diagnostic success with 100% sensitivity and 93% specificity compared to CT angiography. It was noted that anatomical variations may limit its use. CONCLUSION: ODUS was found to have high sensitivity and specificity in the diagnosis of clinical brain death. It may assist in early prognostic assessment and shorten patient follow-up and diagnostic processes.

Neurovascular ultrasound in acute stroke: emergency department applications.

Acute stroke is one of the most common neurologic emergencies encountered by emergency clinicians. While point of care ultrasound has been a core part of emergency clinicians' training and practice for many years, the use of specialized ultrasound modalities in the care of acute ischemic stroke has not been as widely adopted. This review discusses the use of ultrasound in acute stroke, with a focus on applications of interest to emergency clinicians. Transcranial Doppler, carotid Doppler, microembolic signal detection, transthoracic echocardiography, evaluation for collateral circulation and optic nerve sheath diameter measurement are discussed in a case-based format, with a focus on practical applications for emergency clinicians.

Transcranial Ultrasound in the Neurocritical Care Unit.

Ultrasound evaluation of the brain is performed through acoustic windows. Transcranial Doppler has long been used to monitor patients with subarachnoid hemorrhage for cerebral vasospasm. Transcranial color-coded sonography permits parenchymal B-mode imaging and duplex evaluation. Transcranial ultrasound may also be used to assess the risk of delayed cerebral ischemia, screen patients for the presence of elevated intracranial pressure, confirm the diagnosis of brain death, measure midline shift, and detect ventriculomegaly. Transcranial ultrasound should be integrated with other point-of-care ultrasound techniques as an essential skill for the neurointensivist.

[Functional transcranial dopplerography is a diagnostic tool for cognitive impairment syndrome]. / Funktsional'naya transkranial'naya dopplerografiya v diagnostike kognitivnykh narushenii.

Functional transcranial dopplerography (FTCD) is a non-invasive ultrasound examination that allows recording the dynamics of cerebral blood flow parameters under conditions of factors stimulated the activity of the structures of the central nervous system. Judgments about the sensitivity and specificity of FTCD are based on the close connection between changes in the activity of the nervous (somatic) system and the response of regional cerebral blood flow (CBF). The technique is a portable and accessible diagnostic method used in assessing the possibility of expanding functional activity during the recovery period after a stroke. An increase in mental activity in response to the presentation of a cognitive task, accompanied by an increase in glucose and oxygen consumption and naturally requiring an increase in cerebral perfusion parameters, can also be assessed by changes in regional blood flow parameters while maintaining the reactive mechanisms of autoregulation. A search of literature sources was carried out in the electronic databases PubMed and Scopus. For the subject search, Medical Subject Headings were used. A total of 36 sources that mentioned the terms «cognitive function¼ and «functional transcranial Doppler¼ were selected for preliminary analysis. At the present stage, methodological problems are obvious, requiring the development and implementation of a standard package of targeted functional tests to assess cognitive status. Available equipment and software require technological solutions to ensure objective recording of changes in cerebral blood flow during testing and training.

Establishing continuum in Transcranial Doppler characteristics of IIH, migraine and healthy controls- An exploratory study.

BACKGROUND: IIH is a severe form of headache that often has superimposed migraine and often it is very difficult to distinguish the two forms of headache. Intracranial hemodynamics is a relatively unexplored means of distinguishing between the two forms of headache. OBJECTIVES: We aimed to study intracranial flow dynamics using Transcranial Doppler in patients with IIH, migraine, and normal controls. MATERIALS AND METHODS: It was a hospital-based observational study that included 51 people with IIH, 87 people with migraine, and 101 healthy controls and all were subjected to TCD study after detailed clinical examination. RESULTS: Mean age of patients in three groups were similar with the mean age in IIH being 33.41 ± 10.75 (age in years ± SD). Vision loss was present in 66.67% of patients with IIH, and most common field defect was generalized constriction (27.5%). Neuroimaging was abnormal in 94.11% of patients of IIH with mean CSF pressure was 31.27±5.32 cm of water. Of all the TCD-measured velocities, mean flow velocity (MFV) showed a significant difference in all three groups with (p-value <0.001). The pulsatility index, both for middle cerebral arteries as well as ophthalmic arteries showed a significant difference in the three groups with the highest values in IIH patients (p-value<.001). The mean VMR in IIH (1.11±0.32) was lower than the mean VMR in migraine (1.34±0.43) as well as controls (1.49±0.46). CONCLUSION: TCD parameters like MFV and PI are useful parameters that show considerable variation and can be used to differentiate between IIH and migraine.

The prediction of estimated cerebral perfusion pressure with trans-systolic time in preterm and term infants.

It is important to monitor cerebral perfusion in infants because hypo- and hyperperfusion can contribute to neurological injury. This study aimed to clarify the relationship between trans-systolic time (TST) and critical closing pressure (CrCP) or estimated cerebral perfusion pressure (CPPe) in neonates. Moreover, we aimed to determine the TST values in preterm and term infants with stable cerebral perfusion to clarify normative reference data. This multicentre prospective study included infants with arterial lines admitted to the neonatal intensive care units between December 2021 and August 2023. TST, CrCP, and CPPe were calculated using middle cerebral artery waveforms recorded using transcranial Doppler ultrasonography when clinicians collected arterial blood samples. Three hundred and sixty samples were obtained from 112 infants with a gestational age of 32 (interquartile range, 27-37) weeks and a birth weight of 1481 (956-2355) g. TST was positively correlated with CPPe (r = 0.60, p < 0.001), but not with CrCP (r = 0.08, p = 0.10). The normative reference values of TST in preterm and term infants without samples of hyper- or hypocapnia and/or hyper- or hypotension, which may affect cerebral perfusion, were as follows: ≤ 29 weeks, 0.12 (0.11-0.14) s; 30-36 weeks, 0.14 (0.12-0.15) s; and ≥ 37 weeks, 0.16 (0.14-0.17) s, respectively.  Conclusion: TST in neonates significantly correlated with CPPe, but not with CrCP. TST may be a good predictor of cerebral perfusion and potentially have wider clinical applications. What is Known: • Trans-systolic time (TST) is used in evaluating the effects of increased intracranial pressure on cerebral haemodynamics. However, little is known about the efficacy of TST in predicting neonatal cerebral perfusion pressure. What is New: • This study added evidence that TST correlated with estimated cerebral perfusion pressure, but not with critical closing pressure. Additionally, we showed the normative reference values of the TST in preterm and term infants.

Transcranial Doppler cerebrovascular reactivity: Thresholds for clinical significance in cerebrovascular disease.

BACKGROUND AND PURPOSE: Thresholds for abnormal transcranial Doppler cerebrovascular reactivity (CVR) studies are poorly understood, especially for patients with cerebrovascular disease. Using a real-world cohort with cerebral arterial stenosis, we sought to describe a clinically significant threshold for carbon dioxide reactivity (CO2R) and vasomotor range (VMR). METHODS: CVR studies were performed during conditions of breathing room air normally, breathing 8% carbon dioxide air mixture, and hyperventilation. The mean and standard deviation (SD) of CO2R and VMR were calculated for the unaffected side in patients with unilateral stenosis; a deviation of 2 SDs below the mean was chosen as the threshold for abnormal. Receiver operating characteristic (ROC) curves for both sides for patients with unilateral and bilateral stenosis were evaluated for sensitivity (Sn) and specificity (Sp). RESULTS: A total of 133 consecutive CVR studies were performed on 62 patients with stenosis with mean±SD age 55±16 years. Comorbidities included hypertension (60%), diabetes (15%), stroke (40%), and smoking (35%). In patients with unilateral stenosis, mean±SD CO2R for the unaffected side was 1.86±0.53%, defining abnormal CO2R as <0.80%. Mean±SD CO2R for the affected side was 1.27±0.90%. The CO2R threshold predicted abnormal acetazolamide single-photon emission computed tomography (SPECT) (Sn = .73, Sp = .79), CT/MRI perfusion abnormality (Sn = .42, Sp = .77), infarction on MRI (Sn = .45, Sp = .76), and pressure-dependent exam (Sn = .50, Sp = .76). For the unaffected side, mean±SD VMR was 39.5±15.8%, defining abnormal VMR as <7.9%. For the affected side, mean±SD VMR was 26.5±17.8%. The VMR threshold predicted abnormal acetazolamide SPECT (Sn = .46, Sp = .94), infarction on MRI (Sn = .27, Sp = .94), and pressure-dependent exam (Sn = .31, Sp = .90). CONCLUSIONS: In patients with multiple vascular risk factors, a reasonable threshold for clinically significant abnormal CO2R is <0.80% and VMR is <7.9%. Noninvasive CVR may aid in diagnosing and risk stratifying patients with stenosis.

Monitoring of cerebral blood flow autoregulation: physiologic basis, measurement, and clinical implications.

Cerebral blood flow (CBF) autoregulation is the physiologic process whereby blood supply to the brain is kept constant over a range of cerebral perfusion pressures ensuring a constant supply of metabolic substrate. Clinical methods for monitoring CBF autoregulation were first developed for neurocritically ill patients and have been extended to surgical patients. These methods are based on measuring the relationship between cerebral perfusion pressure and surrogates of CBF or cerebral blood volume (CBV) at low frequencies (<0.05 Hz) of autoregulation using time or frequency domain analyses. Initially intracranial pressure monitoring or transcranial Doppler assessment of CBF velocity was utilised relative to changes in cerebral perfusion pressure or mean arterial pressure. A more clinically practical approach utilising filtered signals from near infrared spectroscopy monitors as an estimate of CBF has been validated. In contrast to the traditional teaching that 50 mm Hg is the autoregulation threshold, these investigations have found wide interindividual variability of the lower limit of autoregulation ranging from 40 to 90 mm Hg in adults and 20-55 mm Hg in children. Observational data have linked impaired CBF autoregulation metrics to adverse outcomes in patients with traumatic brain injury, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and in surgical patients. CBF autoregulation monitoring has been described in both cardiac and noncardiac surgery. Data from a single-centre randomised study in adults found that targeting arterial pressure during cardiopulmonary bypass to above the lower limit of autoregulation led to a reduction of postoperative delirium and improved memory 1 month after surgery compared with usual care. Together, the growing body of evidence suggests that monitoring CBF autoregulation provides prognostic information on eventual patient outcomes and offers potential for therapeutic intervention. For surgical patients, personalised blood pressure management based on CBF autoregulation data holds promise as a strategy to improve patient neurocognitive outcomes.

Clinical findings of hyperechoic substantia nigra in patients with Parkinson's disease.

This study aims to analyse hyperechoic substantia nigra (HSN) characteristics and the correlation of HSN with clinical features and blood biomarkers in patients with Parkinson's disease (PD). Transcranial sonography (TCS) evaluations of the substantia nigra (SN) were performed in 40 healthy controls and 71 patients with PD, including patients with SN hyperechogenicity (SN+) and those with normal SN echogenicity (SN-). Evaluation of motor and non-motor symptoms was assessed by a series of rating scales. The uricase method was used to determine serum uric acid (UA) levels, and enzyme-linked immunosorbent assay (ELISA) was used to measure plasma interleukin (IL)-1ß levels. TCS showed 92.50% specificity and 61.97% sensitivity in differentiating PD patients from controls. The area of SN+ contralateral to the side of initial motor symptoms (SNcontra) was larger than that ipsilateral to the side of initial motor symptoms (SNipsi). The PDSN+ group had lower Argentine Hyposmia Rating Scale (AHRS) scores and UA levels than the PDSN- group. Binary logistic regression analysis revealed that AHRS scores and UA levels could be independent predictors for HSN. The larger SN echogenic area (SNL) sizes positively correlated with plasma IL-1ß levels in PD patients with SN+. The present study provides further evidence of the potential of SN echogenicity as an imaging biomarker for PD diagnosis. PD patients with HSN have more severe non-motor symptoms of hyposmia. HSN in PD patients is related to the mechanism of abnormal iron metabolism and microglial activation.

Transcranial sonography in the critical patient.

Transcranial ultrasonography is a non-invasive, bedside technique that has become a widely implemented tool in the evaluation and management of neurocritically ill patients. It constitutes a technique in continuous growth whose fundamentals (and limitations) must be known by the intensivist. This review provides a practical approach for the intensivist, including the different sonographic windows and planes of insonation and its role in different conditions of the neurocritical patients and in critical care patients of other etiologies.

Assessment of Neurovascular Coupling by Spectral Analysis of Cerebral Blood Flow Velocity With Transcranial Doppler.

OBJECTIVE: Neurovascular coupling (NVC) represents the increase in regional blood flow associated with neural activity. The aim here was to describe a new approach to non-invasive measurement of NVC by spectral analysis of the cerebral blood flow velocity (CBFV) with transcranial Doppler. METHODS: In a sample of 20 healthy participants, we monitored systolic CBFV in the left posterior cerebral artery (PCA) during off (eyes closed) and on (flickering checkerboard) periods. The contralateral middle cerebral artery was simultaneously monitored as a control. Each participant was submitted to three experiments, each having five cycles, with increasing duration of the cycles, from 10 s (0.1 Hz) to 20 s (0.05 Hz) and lastly 40 s (0.025 Hz), half the time for on and for off periods, constituting a total of 6 min. The successive cycles were expected to cause oscillation in CBFV in a sinusoidal pattern that could be characterized by spectral analysis. We also measured the classic CBFV overshoot as the relative increase in percentage of systolic CBFV from baseline. The relationship and agreement between the two methods were analyzed by linear regression and Bland-Altman plots. In every participant, a clear peak of amplitude in the PCA CBFV spectrum was discernible at 0.1, 0.05 and 0.025 Hz of visual stimulation. RESULTS: On average, this amplitude was 7.1 ± 2.3%, 10.9 ± 3.5% and 17.3 ± 6.5%, respectively. This response contrasted significantly with an absent peak in middle cerebral artery monitoring (p < 0.0001). The spectral amplitude and classic overshoot were highly correlated and linearly related (p < 0.0001). CONCLUSION: NVC can be quantified by the spectral amplitude of PCA CBFV at slower and higher frequencies of visual stimulation. This method represents an alternative to classic overshoot without the need for stimulus marking or synchronization.

Diagnostic feasibility of middle cerebral artery stenosis or occlusion evaluated by TCCS and CEUS: Repeatability, reproducibility, and diagnostic agreement with DSA.

AIM: This study aimed to evaluate the feasibility of transcranial color-coded sonography (TCCS) and contrast-enhanced ultrasound (CEUS) in assessing middle cerebral artery (MCA) stem stenosis or occlusion compared to digital subtraction angiography (DSA). METHODS: A total of 48 cases including 96 MCAs suspected stem stenosis or obstruction in the MCA were assessed by TCCS, CE-TCCS, and DSA. The diameters of the most severe stenosis (Ds), proximal normal artery (Dn), and diameter stenosis rate of MCA were measured using both the color doppler flow imaging (CDFI) modality of TCCS or CEUS and the CEUS imaging modality. The intraclass correlation coefficients (ICCs) and 95 % confidence intervals (CI) were evaluated, and a weighted Kappa value was used to evaluate the intra-observer agreement, inter-observer agreement, agreement between CDFI modality and DSA stenosis or occlusion, and agreement between CEUS imaging modality and DSA stenosis or occlusion. RESULTS: The ICC results indicated excellent repeatability and reproducibility (all ICCs > 0.75; weighted Kappa values >0.81). Compared with DSA, the weighted Kappa values and 95 % CIs of stenosis (the first measurement was taken by two observers) of CDFI modality and CEUS imaging modality were 0.175 (0.041, 0.308) and 0.779 (0.570, 0.988) for observers A and 0.181 (0.046, 0.316) and 0.779 (0.570, 0.988) for observers B respectively. CONCLUSION: This study indicates that inter- and intra-observer agreements were good for the direct method of measuring percentages of MCA stenosis by TCCS and CEUS. CEUS imaging modality is a new and reliable imaging modality approach to evaluate the MCAs stenosis and occlusion.

The size distribution of the agitated saline microbubbles for contrast transcranial Doppler generated using standard manual methods.

Agitated saline microbubbles (MBs) are a common contrast agent for determining right-to-left shunt (RLS) by the contrast transcranial Doppler (c-TCD). The size of the generated bubbles is not standardized in clinical practice. MBs were generated using the recommended manual method by reciprocating motion through two syringes. The bubble size distributions (BSD) were measured using the microscopic shadow imaging technique. The results show that the diameter of MBs is mainly distributed between 10 and 100 µm, the mean bubble size is between 21 and 34 µm, the Sauter mean diameter (D32) is primarily between 50 and 300 µm, and the standard deviation (SD) is between 6 and 17 µm in 80 experiments. It provides a more accurate basis for the recommended manual method instability. The high variance values of the BSD indicate that the manual method has low stability and repeatability. The results of this study can be useful for further improvement of the reliability of c-TCD in detecting RLS. RESEARCH HIGHLIGHTS: This study provided the first detailed descriptions of the MBs size distribution in a flowing contrast agent by the microscopic shadow imaging technique. It reveals significant differences in the bubble size of manual foaming during repeated manipulations for each individual and between individuals.

Noninvasive Neuromonitoring Modalities in Children Part I: Pupillometry, Near-Infrared Spectroscopy, and Transcranial Doppler Ultrasonography.

BACKGROUND: Noninvasive neuromonitoring in critically ill children includes multiple modalities that all intend to improve our understanding of acute and ongoing brain injury. METHODS: In this article, we review basic methods and devices, applications in clinical care and research, and explore potential future directions for three noninvasive neuromonitoring modalities in the pediatric intensive care unit: automated pupillometry, near-infrared spectroscopy, and transcranial Doppler ultrasonography. RESULTS: All three technologies are noninvasive, portable, and easily repeatable to allow for serial measurements and trending of data over time. However, a paucity of high-quality data supporting the clinical utility of any of these technologies in critically ill children is currently a major limitation to their widespread application in the pediatric intensive care unit. CONCLUSIONS: Future prospective multicenter work addressing major knowledge gaps is necessary to advance the field of pediatric noninvasive neuromonitoring.

Transcranial sonography in neurodegeneration with brain iron accumulation disorders.

BACKGROUND: Transcranial Sonography is a non-invasive technique that has been used as a diagnostic tool for a variety of neurodegenerative disorders. However, the utility and potential application of this technique in NBIA disorders is scarce and inconclusive. METHODS: In this cross-sectional retrospective case-control study, the echogenicity of Substantia Nigra (SN), Lentiform Nucleus (LN), and Diameter of the Third Ventricle (DTV) were assessed by TCS in genetically confirmed NBIA patients referring to the movement disorder clinic. The normal echogenicity area of SN was defined based on the 90th percentile of an age-and-gender-matched control group. NBIA patients underwent neurologic examination at each visit, but their brain magnetic resonance imaging and demographics were extracted from electronic records. RESULTS: Thirty-five NBIA patients of four subtypes with a mean disease duration of 10.54 years and 35 controls were enrolled. The normally defined SN echogenicity in controls was 0.23 cm2. DTV and SN echogenicity areas were significantly higher in patients compared to the controls (P = 0.002 and < 0.001, respectively). Around 85% and 63% of the patients showed LN and SN hyperechogenicity at least on one side, respectively. Disease duration was positively correlated with DTV (r = 0.422, p = 0.015). Cases with Pantothenate Kinase Associated Neurodegeneration (n = 23) also had significantly higher DTV and SN echogenicity area compared to the controls. CONCLUSION: Despite most NBIA patients displayed increased DVT and higher SN and LN hyperechogenicity than healthy controls, the discriminatory role of TCS on different NBIA subtypes remains to be determined.

Comparison of computational fluid dynamics with transcranial Doppler ultrasound in response to physiological stimuli.

Cerebrovascular haemodynamics are sensitive to multiple physiological stimuli that require synergistic response to maintain adequate perfusion. Understanding haemodynamic changes within cerebral arteries is important to inform how the brain regulates perfusion; however, methods for direct measurement of cerebral haemodynamics in these environments are challenging. The aim of this study was to assess velocity waveform metrics obtained using transcranial Doppler (TCD) with flow-conserving subject-specific three-dimensional (3D) simulations using computational fluid dynamics (CFD). Twelve healthy participants underwent head and neck imaging with 3 T magnetic resonance angiography. Velocity waveforms in the middle cerebral artery were measured with TCD ultrasound, while diameter and velocity were measured using duplex ultrasound in the internal carotid and vertebral arteries to calculate incoming cerebral flow at rest, during hypercapnia and exercise. CFD simulations were developed for each condition, with velocity waveform metrics extracted in the same insonation region as TCD. Exposure to stimuli induced significant changes in cardiorespiratory measures across all participants. Measured absolute TCD velocities were significantly higher than those calculated from CFD (P range < 0.001-0.004), and these data were not correlated across conditions (r range 0.030-0.377, P range 0.227-0.925). However, relative changes in systolic and time-averaged velocity from resting levels exhibited significant positive correlations when the distinct techniques were compared (r range 0.577-0.770, P range 0.003-0.049). Our data indicate that while absolute measures of cerebral velocity differ between TCD and 3D CFD simulation, physiological changes from resting levels in systolic and time-averaged velocity are significantly correlated between techniques.

TCCD Fusion Imaging to Estimate Intracranial Pressure and Tissue Displacement with Large Hemispheric Infarction.

BACKGROUND: Despite breakthroughs in stroke treatment, some patients still experience large infarctions of the cerebral hemispheres resulting in mass effect and tissue displacement. The evolution of mass effect is currently monitored using serial computed tomography (CT) imaging. However, there are patients who are ineligible for transport, and there are limited options for bedside monitoring of unilateral tissue shift. METHODS: We used fusion imaging for overlaying transcranial color duplex with CT angiography. This method allows overlay of live ultrasound on top of CT or magnetic resonance imaging scans. Patients with large hemispheric infarctions were eligible to participate. Position data from the source files were used and matched with live imaging and correlation to magnetic probes on the patient's forehead and ultrasound probe. Shift of cerebral parenchyma, displacement of the anterior cerebral arteries, basilary artery and third ventricle were analyzed, as well as pressure on the midbrain, and the displacement of the basilar artery on the head were analyzed. Patients received multiple examinations in addition to standard care of treatment with CT imaging. RESULTS: The sensitivity for diagnosing a shift of 3 mm with fusion imaging was 100%, with a specificity of 95%. No side effects or interactions with critical care equipment were recorded. CONCLUSIONS: Fusion imaging is an easy method to access and acquire measurements for critical care patients and follow-up of tissue and vascular displacement after stroke. Fusion imaging may be a decisive support for indicating hemicraniectomy.