Intracranial Flow Research Articles

Cerebrovascular super-resolution 4D Flow MRI - Sequential combination of resolution enhancement by deep learning and physics-informed image processing to non-invasively quantify intracranial velocity, flow, and relative pressure.

The development of cerebrovascular disease is tightly coupled to regional changes in intracranial flow and relative pressure. Image-based assessment using phase contrast magnetic resonance imaging has particular promise for non-invasive full-field mapping of cerebrovascular hemodynamics. However, estimations are complicated by the narrow and tortuous intracranial vasculature, with accurate image-based quantification directly dependent on sufficient spatial resolution. Further, extended scan times are required for high-resolution acquisitions, and most clinical acquisitions are performed at comparably low resolution (>1mm) where biases have been observed with regard to the quantification of both flow and relative pressure. The aim of our study was to develop an approach for quantitative intracranial super-resolution 4D Flow MRI, with effective resolution enhancement achieved by a dedicated deep residual network, and with accurate quantification of functional relative pressures achieved by subsequent physics-informed image processing. To achieve this, our two-step approach was trained and validated in a patient-specific in-silico cohort, showing good accuracy in estimating velocity (relative error: 15.0±0.1%, mean absolute error (MAE): 0.07±0.06m/s, and cosine similarity: 0.99±0.06 at peak velocity) and flow (relative error: 6.6±4.7%, root mean square error (RMSE): 0.56mL/s at peak flow), and with the coupled physics-informed image analysis allowing for maintained recovery of functional relative pressure throughout the circle of Willis (relative error: 11.0±7.3%, RMSE: 0.3±0.2mmHg). Furthermore, the quantitative super-resolution approach is applied to an in-vivo volunteer cohort, effectively generating intracranial flow images at <0.5mm resolution and showing reduced low-resolution bias in relative pressure estimation. Our work thus presents a promising two-step approach to non-invasively quantify cerebrovascular hemodynamics, being applicable to dedicated clinical cohorts in the future.

A novel endoleak classification for intracranial aneurysm flow diversion: A retrospective case series.

Although flow diversion (FD) is safe and effective in the treatment of intracranial aneurysms, a subset tends to continue filling on serial angiography. Risk factors for failed flow diversion include old age, large aneurysm size, and overstenting an adjacent end-arterial vessel. The hemodynamic modes of persistent aneurysm filling, or 'endoleaks', after FD are poorly understood. This study aims to characterize the various types of endoleaks following aneurysmal FD. We performed a retrospective review of a prospectively maintained database of all endovascular procedures performed at a single institution between 2017 and 2021. Patients were included if they demonstrated evidence of unique modes of intracranial aneurysm filling after FD. Data regarding treatment, follow-up angiography, as well as clinical course were collected. Five patients (mean age 50 years, four females) were included with mean 19-month angiographic follow-up. Five major endoleak types are proposed: Type 1 - due to graft porosity (A - low flow, B - high flow), Type 2 -through an overstented branch vessel, Type 3 - via stent migration no longer covering aneurysmal neck, Type 4 - endoleak due to malapposition of the stent wall, and Type 5 - endoleak via collateralization from adjacent blood vessels. All endoleak types were represented, except for the Type 4 endoleak. We propose an endoleak classification scheme to describe the hemodynamic modes of failure following FD of intracranial aneurysms. Future studies are needed to evaluate the natural history of aneurysmal filling following FD and retreatment success according to endoleak type.

Hemodynamic outcomes of stenting for vertebrobasilar insufficiency in patients with a low flow state.

The Vertebrobasilar Flow Evaluation and Risk of Transient Ischemic Attack and Stroke (VERiTAS) study determined patients with low flow in their vertebrobasilar (VB) system are at increased risk of recurrent stroke. Endovascular interventions such as angioplasty and stenting are reserved for patients with refractory symptoms; however, few series to date have demonstrated either hemodynamic or clinical outcomes in this high-risk patient group. We present our combined institutional series of patients with symptomatic VB atherosclerotic disease and low-flow state who underwent angioplasty and stenting. Retrospective chart review of patients undergoing angioplasty and stenting for symptomatic VB atherosclerotic disease at two institutions was performed. Clinical and radiographical outcomes were collected including flow rates using quantitative MRA (QMRA) pre- and post-stenting. Seventeen patients underwent angioplasty and stenting for symptomatic VB atherosclerotic disease and met VERiTAS low-flow state criteria. There were four cases (23.5%) of periprocedural stroke, two of which were minor and transient. The stent was placed intracranially in 82.4% of patients. Basilar and bilateral posterior cerebral artery (PCA) flows significantly improved post-stenting (p < 0.05) and normalized based upon VERiTAS criteria in all patients. Fourteen patients had delayed QMRA at mean follow-up 20 months demonstrating appropriate patency and flow post-stenting. Two patients (10%) had recurrent stroke, one from medication nonadherence and in-stent thrombosis, and the other from a procedural dissection that subsequently became symptomatic. Our series demonstrates angioplasty and stenting significantly improve intracranial flow over long-term. Angioplasty and stenting may improve the natural history of low-flow VB atherosclerotic disease.

Neuroimaging assessment of pediatric cerebral changes associated with SARS-CoV-2 infection during pregnancy.

SARS-CoV-2 infection and perinatal neurologic outcomes are still not fully understood. However, there is recent evidence of white matter disease and impaired neurodevelopment in newborns following maternal SARS-CoV-2 infection. These appear to occur as a consequence of both direct viral effects and a systemic inflammatory response, with glial cell/myelin involvement and regional hypoxia/microvascular dysfunction. We sought to characterize the consequences of maternal and fetal inflammatory states in the central nervous system of newborns following maternal SARS-CoV-2 infection. We conducted a longitudinal prospective cohort study from June 2020 to December 2021, with follow-up of newborns born to mothers exposed or not exposed to SARS-CoV-2 infection during pregnancy. Brain analysis included data from cranial ultrasound scans (CUS) with grayscale, Doppler studies (color and spectral), and ultrasound-based brain elastography (shear-wave mode) in specific regions of interest (ROIs): deep white matter, superficial white matter, corpus callosum, basal ganglia, and cortical gray matter. Brain elastography was used to estimate brain parenchymal stiffness, which is an indirect quantifier of cerebral myelin tissue content. A total of 219 single-pregnancy children were enrolled, including 201 born to mothers exposed to SARS-CoV-2 infection and 18 from unexposed controls. A neuroimaging evaluation was performed at 6 months of adjusted chronological age and revealed 18 grayscale and 21 Doppler abnormalities. Predominant findings were hyperechogenicity of deep brain white matter and basal ganglia (caudate nuclei/thalamus) and a reduction in the resistance and pulsatility indices of intracranial arterial flow. The anterior brain circulation (middle cerebral and pericallosal arteries) displayed a wider range of flow variation than the posterior circulation (basilar artery). Shear-wave US elastography analysis showed a reduction in stiffness values in the SARS-CoV-2 exposed group in all analyzed regions of interest, especially in the deep white matter elasticity coefficients (3.98 ± 0.62) compared to the control group (7.76 ± 0.77); p-value < 0.001. This study further characterizes pediatric structural encephalic changes associated with SARS-CoV-2 infection during pregnancy. The maternal infection has been shown to be related to cerebral deep white matter predominant involvement, with regional hyperechogenicity and reduction of elasticity coefficients, suggesting zonal impairment of myelin content. Morphologic findings may be subtle, and functional studies such as Doppler and elastography may be valuable tools to more accurately identify infants at risk of neurologic damage.

Balloon-Assisted Catheterization of Occluded Carotid Artery (BOCA) Technique in Acute Stroke.

Acute ischemic stroke from tandem occlusion of internal carotid artery (ICA) poses a technical challenge to neurointerventionalists. To present a novel balloon-assisted catheterization of occluded carotid artery (BOCA) technique used for rapid and effective catheterization of occluded/critically stenosed ICA in tandem occlusion. A retrospective review of 10 patients with tandem carotid occlusion, treated with BOCA technique for revascularization between July 2020 and June 2021, was performed. Clinical, radiographic, and procedural data; details of BOCA technique; complications; and outcomes were reviewed. Of the 10 patients, 8 (80%) had complete occlusion of the cervical ICA and the remaining 2 had high-grade stenosis with poor intracranial flow. The mean age was 63.2 years. The mean presenting NIH Stroke Scale was 13.4. The BOCA technique resulted in recanalization of ICA in all patients and allowed mechanical thrombectomy of middle cerebral artery. Thrombolysis in cerebral infarction grade 2b/3 was achieved in all 10 patients. The mean groin-to-reperfusion time was 41.4 minutes. The mean internal carotid artery stenosis was 99.7% preoperatively and 41.1% postoperatively. Only one patient needed stent at the end of the procedure because of dissection. The BOCA technique can be used in distal first approach for acute stroke from tandem ICA occlusion. This technique allows direct guide catheterization of occluded ICA by tracking over a partially inflated balloon.

Effect of antisiphon devices on ventriculoperitoneal shunt drainage dynamics in growing children.

Infants and small children face changing boundary conditions when treated with a ventriculoperitoneal shunt (VPS) for hydrocephalus. There are no systematic data describing shunt drainage behavior and changes over time in a growing child. Using a child-adapted patient simulator, the authors investigated the drainage behaviors of fixed differential pressure (DP) valves and adjustable valves with devices for preventing overdrainage in children of different ages. Three miniNAV DP valves with a 10-cm H2O medium-pressure setting (MN10) and three adjustable proGAV2.0 valves with a 25-cm H2O gravitational unit (GU) at low 5-cm H2O opening pressure (PG5) and medium 10-cm H2O opening pressure (PG10) settings were each investigated with a hardware-in-the-loop test bed. This test bed consisted of a posture motion mechanism and two pressure compartments that mimicked intracranial and abdominal pressures and was used to test the VPS under realistic in vitro conditions. Body orientation and length were physically set according to the child's age. The software simulated the physiological situations of children aged 1, 5, and 10 years. All valves were tested according to these specifications, with 5 runs for 1 hour each in the horizontal, vertical, and horizontal positions. Intracranial pressure (ICP) and VPS flow were measured, and the respective cerebrospinal fluid volume changes and ICP set value were computed. The drainage parameters increased with age in all valves in the vertical position, with that of MN10 being pronounced in the 1-year-old simulation. The GU values in PG5 and PG10 substantially reduced drainage compared with MN10. PG10 prevented drainage in the 1-year-old and 5-year-old setups, but there was some drainage at physiological ICP in the 10-year-old setup. In contrast, MN10 produced the largest decreases in ICP across all ages and positions, and overdrainage resulted in insufficient ICP recovery in the subsequent horizontal position. ICP levels were mostly constant with PG10 at all ages. This study shows that unprotected DP valves may lead to overdrainage in infants, whereas low-pressure GU valves can prevent overdrainage through 5 years and medium-pressure GU valves admit physiological ICP through at least 10 years. Therefore, devices for preventing overdrainage should be included in the first implanted shunt, and opening pressure should be adjusted as the child grows.

Near-wall hemodynamic parameters quantification in in vitro intracranial aneurysms with 7 T PC-MRI

ObjectiveWall shear stress (WSS) and its derived spatiotemporal parameters have proven to play a major role on intracranial aneurysms (IAs) growth and rupture. This study aims to demonstrate how ultra-high field (UHF) 7 T phase contrast magnetic resonance imaging (PC-MRI) coupled with advanced image acceleration techniques allows a highly resolved visualization of near-wall hemodynamic parameters patterns in in vitro IAs, paving the way for more robust risk assessment of their growth and rupture.Materials and methodsWe performed pulsatile flow measurements inside three in vitro models of patient-specific IAs using 7 T PC-MRI. To this end, we built an MRI-compatible test bench, which faithfully reproduced a typical physiological intracranial flow rate in the models.ResultsThe ultra-high field 7 T images revealed WSS patterns with high spatiotemporal resolution. Interestingly, the high oscillatory shear index values were found in the core of low WSS vortical structures and in flow stream intersecting regions. In contrast, maxima of WSS occurred around the impinging jet sites.ConclusionsWe showed that the elevated signal-to-noise ratio arising from 7 T PC-MRI enabled to resolve high and low WSS patterns with a high degree of detail.

Abstract Number ‐ 70: Combined Trans‐arterial Flow Diversion and Trans‐venous Embolization Management of High‐Flow Traumatic Cavernous‐Carotid Fistula (CCF)

Introduction Carotid‐Cavernous fistulas (CCF) are abnormal vascular shunts between the internal carotid artery (ICA) and the cavernous sinus. Most commonly due to trauma (75%), CCF occurs in 4%(1) of skull‐base fracture patients. Visual impairment, diplopia, and headache are typical presenting symptoms (88%). Proptosis, chemosis, ophthalmoparesis, and orbital bruits are notable exam findings. Cerebral angiography is the gold standard for diagnosis, showing cavernous sinus enlargement and ophthalmic vein or leptomeningeal vessel dilatation. CCF is typically treated endovascularly andballoon embolization has achieved cure rates of 88–99%(2). Successful obliteration using stents, however, has been reported(3, 4). While both trans‐arterial and the trans‐venous approach embolization are feasible depending on local vascular anatomy and accessibility of fistula points, the combination of trans‐arterial and trans‐venous approach is rarely employed.We present a case of traumatic, high‐flow CCF treated with combined trans‐arterial and trans‐venous coiling embolization and telescoped flow‐diverting stents. Methods A case report of successful treatment of traumatic high‐flow CCF with a combined trans‐arterial and trans‐venous coiling embolization with telescoped flow‐diverting stents. Results A 26‐year‐old woman presented with right eye proptosis, periorbital ecchymosis, and chemosistwo weeks after severe closed head injury treated with decompressive hemicraniectomy and subdural hematoma evacuation. Examination was notable for right eye blindness without light perception and right‐sided third, fourth, and sixth cranial nerve palsies and elevated intraocular pressure. CT head showed a skull base fracture involving the right carotid canal and angiography of ICA confirmed a high‐flow multi‐channel right CCF with diminished intracranial arterial flow and engorged bilateral ophthalmic veins. After unsuccessful attempts to catheterize the fistula via arterial approach, superior‐segment coil embolization was performed using an inferior petrosal venous approach; but further embolization of the cavernous sinus was unsuccessful. Using the cavernous‐petrous segment of the right ICA, a flow‐diversion stent was placed that significantly decreased cross‐fistula blood flow, improved intracranial arterial flow, and reduced bilateral ophthalmic vein congestion. After two months, intraocular pressure normalized and right eye vision returned, though moderate exophthalmos persisted. Angiography showed decreased but persistent residual CCF flow. Another flow‐diversion stent was successfully placed via trans‐arterial approach, covering the previous pipeline stent through petrous‐to‐ophthalmic right ICA. Three‐month follow‐up angiogram showed closure of the CCF with complete restoration of right eye vision. She ultimately underwent right cranioplasty and was able to return to work. Conclusions A combined trans‐venous coiling embolization and trans‐arterial flow‐diversion stenting may be effectively employed in the treatment of CCF with reversal of clinical symptoms and restoration of visual loss. Larger studies are needed to explore the role of this combined approach in the management of CCF.

Intracranial arterial flow velocity mapping in quantitative time-of-flight MR angiography using deep machine learning

PurposeTo evaluate the application of deep machine learning (DML) to 3D quantitative time-of-flight (qTOF) magnetic resonance angiography (MRA) to measure blood flow velocity within the intracranial arteries. Materials and methodsIntracranial qTOF MRA was acquired in 15 subjects at 3 T. Blood flow velocity quantitation with qTOF MRA was done using a non-DML computer-vision procedure, and using convolutional DML neural networks. 3D phase contrast (PC) MRA was used as the comparator. Using PC velocity measures as the output target and qTOF two-echo source image data as inputs, DML neural networks were trained to predict component blood flow velocities. Total velocities and peak intracranial arterial blood flow velocities were computed from component velocities. ResultsCompared to non-DML image analysis, DML-based analysis of qTOF MRA image data improved agreement with PC for mean component velocity (intraclass correlation coefficient (ICC) = 0.966 versus 0.939), mean total velocity (ICC = 0.835 versus 0.723), and peak velocity (ICC = 0.816 versus 0.597), as well as narrowed the 95% Bland-Altman limits of agreement for mean component velocity ([−5.16, +4.31]cm/s versus [−6.86, +6.53]cm/s), mean total velocity ([−6.78,+3.59]cm/s versus [−9.39, +7.09]cm/s) and peak velocity ([−13.5,+10.2]cm/s versus [−21.3, +10.2]cm/s). Compared to non-DML analysis, DML image analysis reduced the root-mean-square deviation from PC velocity measures by 28%–36%, and shortened calculation times by 35-fold. ConclusionThe application of DML image analysis to intracranial qTOF MRA for velocity quantitation markedly shortened calculation times, substantially improved the agreement of component, total, and peak arterial blood flow velocities, and provided excellent agreement of hemodynamic measures with respect to 3D PC.

The role of neuroimaging in the determination of brain death.

Brain death is the irreversible cessation of all brain function. Although protocols for its determination vary among countries, the concept of brain death is widely accepted, despite ethical and religious issues. The pathophysiology of brain death is related to hypoxia and ischemia in the setting of extensive brain injury. It is also related to the effects of brain edema, which increases intracranial pressure, leading to cerebral circulatory arrest. Although the diagnosis of brain death is based on clinical parameters, the use of neuroimaging to demonstrate diffuse brain injury as the cause of coma prior to definitive clinical examination is a prerequisite. Brain computed tomography (CT) and magnetic resonance imaging (MRI) demonstrate diffuse edema, as well as ventricular and sulcal effacement, together with brain herniation. Angiography (by CT or MRI) demonstrates the absence of intracranial arterial and venous flow. In some countries, electroencephalography, cerebral digital subtraction angiography, transcranial Doppler ultrasound, or scintigraphy/single-photon emission CT are currently used for the definitive diagnosis of brain death. Although the definition of brain death relies on clinical features, radiologists could play an important role in the early recognition of global hypoxic-ischemic injury and the absence of cerebral vascular perfusion.

A mathematical framework for the dynamic interaction of pulsatile blood, brain, and cerebrospinal fluid

BackgroundShedding light on less-known aspects of intracranial fluid dynamics may be helpful to understand the hydrocephalus mechanism. The present study suggests a mathematical framework based on in vivo inputs to compare the dynamic interaction of pulsatile blood, brain, and cerebrospinal fluid (CSF) between the healthy subject and the hydrocephalus patient. MethodThe input data for the mathematical formulations was pulsatile blood velocity, which was measured using cine PC-MRI. Tube law was used to transfer the created deformation by blood pulsation in the vessel circumference to the brain domain. The pulsatile deformation of brain tissue with respect to time was calculated and considered to be inlet velocity in the CSF domain. The governing equations in all three domains were continuity, Navier-Stokes, and concentration. We used Darcy law with defined permeability and diffusivity values to define the material properties in the brain. ResultsWe validated the preciseness of the CSF velocity and pressure through the mathematical formulations with cine PC-MRI velocity, experimental ICP, and FSI simulated velocity and pressure. We used the analysis of dimensionless numbers including Reynolds, Womersley, Hartmann, and Peclet to evaluate the characteristics of the intracranial fluid flow. In the mid-systole phase of a cardiac cycle, CSF velocity had the maximum value and CSF pressure had the minimum value. The maximum and amplitude of CSF pressure, as well as CSF stroke volume, were calculated and compared between the healthy subject and the hydrocephalus patient. ConclusionThe present in vivo-based mathematical framework has the potential to gain insight into the less-known points in the physiological function of intracranial fluid dynamics and the hydrocephalus mechanism.

Increased very low frequency pulsations and decreased cardiorespiratory pulsations suggest altered brain clearance in narcolepsy

BackgroundNarcolepsy is a chronic neurological disease characterized by daytime sleep attacks, cataplexy, and fragmented sleep. The disease is hypothesized to arise from destruction or dysfunction of hypothalamic hypocretin-producing cells that innervate wake-promoting systems including the ascending arousal network (AAN), which regulates arousal via release of neurotransmitters like noradrenalin. Brain pulsations are thought to drive intracranial cerebrospinal fluid flow linked to brain metabolite transfer that sustains homeostasis. This flow increases in sleep and is suppressed by noradrenalin in the awake state. Here we tested the hypothesis that narcolepsy is associated with altered brain pulsations, and if these pulsations can differentiate narcolepsy type 1 from healthy controls.MethodsIn this case-control study, 23 patients with narcolepsy type 1 (NT1) were imaged with ultrafast fMRI (MREG) along with 23 age- and sex-matched healthy controls (HC). The physiological brain pulsations were quantified as the frequency-wise signal variance. Clinical relevance of the pulsations was investigated with correlation and receiving operating characteristic analysis.ResultsWe find that variance and fractional variance in the very low frequency (MREGvlf) band are greater in NT1 compared to HC, while cardiac (MREGcard) and respiratory band variances are lower. Interestingly, these pulsations differences are prominent in the AAN region. We further find that fractional variance in MREGvlf shows promise as an effective bi-classification metric (AUC = 81.4%/78.5%), and that disease severity measured with narcolepsy severity score correlates with MREGcard variance (R = −0.48, p = 0.0249).ConclusionsWe suggest that our novel results reflect impaired CSF dynamics that may be linked to altered glymphatic circulation in narcolepsy type 1.

Cardiac and Respiratory Influences on Intracranial and Neck Venous Flow, Estimated Using Real-Time Phase-Contrast MRI.

The study of brain venous drainage has gained attention due to its hypothesized link with various neurological conditions. Intracranial and neck venous flow rate may be estimated using cardiac-gated cine phase-contrast (PC)-MRI. Although previous studies showed that breathing influences the neck’s venous flow, this aspect could not be studied using the conventional segmented PC-MRI since it reconstructs a single cardiac cycle. The advent of real-time PC-MRI has overcome these limitations. Using this technique, we measured the internal jugular veins and superior sagittal sinus flow rates in a group of 16 healthy subjects (12 females, median age of 23 years). Comparing forced-breathing and free-breathing, the average flow rate decreased and the respiratory modulation increased. The flow rate decrement may be due to a vasoreactive response to deep breathing. The respiratory modulation increment is due to the thoracic pump’s greater effect during forced breathing compared to free breathing. These results showed that the breathing mode influences the average blood flow and its pulsations. Since effective drainage is fundamental for brain health, rehabilitative studies might use the current setup to investigate if respiratory exercises positively affect clinical variables and venous drainage.

CARD27: The Effect of Permissive Hypertension on Cerebral Perfusion in VAD Patients with Embolic Stroke

Study: This study aims to investigate the effect of permissive hypertension, a deliberate rise in Mean Arterial Pressure (MAP), on cerebral perfusion in Left Ventricular Assist Device (LVAD) patients with embolic stroke. Methods: A previously published Lumped Parameter Model (LPM) of the human circulation, including pulmonary and systemic circulation, as well as all four cardiac chambers and an LVAD, is divided into circulation of the upper and lower body. The upper circulation is further divided into extracranial and intracranial vessels to study brain perfusion as a function of MAP, as well as peripheral and intracranial resistance. Actual LVAD H-Q characteristic curves model the instantaneous LVAD response to a rise in MAP and the differential increase in resistance between the intracranial region suffering a stroke and the remaining circulation. The resulting changes in intracranial flow rate as MAP increases and vascular resistance is altered are analyzed. Increased resistance in intracranial vasculature is incorporated into a model of a typical embolic stroke, and its influence on cerebral perfusion is studied for a range of LVAD speeds and MAP values. Results: In LVAD patients with embolic stroke, intracranial flow significantly decreases as MAP is allowed to rise. These findings are robust at any LVAD speed, consistent with a significant reduction in LVAD flow with increased afterload. This counterintuitive result of permissive hypertension in LVAD patients is captured by the LPM model of embolic stroke, whereby the increase in intracranial resistance decreases cerebral perfusion even further via a decrease in total cardiac output associated with the increase in MAP. Third-generation LVADs are known to be afterload sensitive. Our results show that a mere increase in MAP from 70 to 80 mmHg decreases cerebral blood flow by a commensurate 15%, thus increasing infarct size, which is quite deleterious (see Fig. 1). Our study confirms there is no role for permissive hypertension in LVAD patients with embolic stroke. Figure 1. Cranial flow rate (Qcranial) as a function of MAP for no embolism (purple) and embolism (teal) cases and for 2400 RPM (circles) and 2800 RPM (squares) LVAD speeds.

0081 Physiologic anatomy, use of Infra-Red Thermography in Hypersomnia

Abstract Introduction In the words of Michel Salmon, " Between anatomy and physiology there is room for a functional anatomy and for a physiologic anatomy “. This concept was applied to analyze our (1) Sleep Research 21, 1992,341 (2) Sleep Research 22, 1993, 363, and (3) SLEEP 31, 2008, A219 publications on patients with Hypersomnia who had intracranial and extracranial blood flow evaluations. Methods For “Functional Anatomy”, Intracranial cerebral blood flow was done with Xenon 133 inhalation. For “Physiologic Anatomy”, Extracranial facial blood flow Imaging, Infra-Red thermography was done. 1992,3 and 2008 data was classified: Groups I, II and III. Group I had Intracranial and Extracranial blood flow study, 5% CO2 inhalation. Groups II had Extracranial flow study with 5 % CO2 and 100 % Oxygen inhalation. Groups III had Extracranial flow study 100 % Oxygen inhalation. Response interpretation: Normal response to 5% CO2, vasodilation. For 100% Oxygen / hyperoxia, vasoconstriction. Response is considered as normal or abnormal, if response is absent or paradoxical. Results Group I: All three patients 5% CO2 inhalation, intracranial Functional anatomy vasomotor response normal. Physiological Anatomy response abnormal. Group II, Physiological Anatomy study. 8 patients. CO2 response, 7/8 vasoconstriction, abnormal response. 100% Oxygen challenge, 4/8 had no vasoconstriction, abnormal response. Group III: Physiological anatomy. 7 patients tested with 100% Oxygen challenge. 6/7 abnormal response, (1 vasoconstriction, 4 no response, 2 vasodilation). Total of 18 patients in all groups, physiological anatomy/ Extracranial flow vasomotor response was abnormal in 16/18, (Group I = 3, Group II = 7, and Group III = 6) Conclusion In hypersomnia patients vasomotor testing, Functional Anatomy, intracranial flow vasomotion normal in 3/3 for hypercarbia inhalation. For Physiologic Anatomy, using Infra-Red Thermography to image extracranial facial blood flow (not coupled with metabolism) vasomotion was abnormal in 16/18 patients. 5% CO2 and 100% Oxygen inhalation used as contrast agents is well tolerated and facilitates imaging vasomotor dysfunction in the facial blood flow, trigeminal angiosomes, which can be correlated with hypersomnia. Association between trigeminal system and the hypocretin receptor 1 gene HCRTR1 gene has been reported. Support (If Any) None.

Pre-manipulative cervical spine testing and sustained rotation do not influence intracranial hemodynamics: an observational study with transcranial Doppler ultrasound

ABSTRACT Introduction Manual joint mobilization and manipulation are recommended therapeutic interventions for people with neck pain. High-velocity thrust and sustained techniques have an uncertain association with serious arterial trauma. The validity of pre-manipulative tests of the cervical spine is often questioned, and the understanding of the effect of head/neck position on blood flow is still incomplete. Most of the evidence concerning hemodynamics in this area relates to extracranial flow (vertebral and carotid artery). Less is understood about the effects on intracranial flow while performing pre-manipulative tests and sustained positions like end of range cervical rotation mobilization. The aim of the study was to assess the influence of commonly used evaluation and treatment positions on intracranial hemodynamic parameters. Method A randomized, cross-over observational study using ultrasonography on healthy subjects (n = 19) was conducted to measure hemodynamic parameters (peak systolic velocity and end diastolic maximum) of intracranial arterial systems. Two test positions (sustained pre-manipulative thrust C0-1 and sustained cervical end of range rotation) were compared with a sham position for each test position. Results :Neither the sequence of tests performed nor an independent variable (the two positions) had a significant effect (p < 0.05) on peak systolic velocity (PSV) or end diastolic maximum (EDM). Discussion No effects from commonly used assessment and treatment of neck positions on hemodynamic parameters were found. This is consistent with previous studies. Further study is indicated on people with symptoms and known pathologies.

Human “live cadaver” neurovascular model for proximal and distal mechanical thrombectomy in stroke

BackgroundPreclinical testing platforms that accurately replicate complex human cerebral vasculature are critical to advance neurointerventional knowledge, tools, and techniques. Here, we introduced and validated a human “live cadaveric” head-and-neck neurovascular...

Intracranial Flow Volume Estimation in Patients with Internal Carotid Artery Occlusion.

(1) Background: Carotid artery occlusion (CAO) in population studies has a reported prevalence of about 6 per 100,000 people; however, the data may be underestimated. CAO carries a significant risk of stroke. Up to 15% of large artery infractions may be secondary to the CAO, and in 27–38% of patients, ischaemic stroke is a first presentation of the disease. The presence of sufficient and well-developed collateral circulation has a protective influence, being a good prognostic factor in patients with carotid artery disease, both chronic and acute. Understanding the mechanisms and role of collateral circulation may be very important in the risk stratification of such patients. (2) Materials and Methods: This study included 46 patients (mean age: 70.5 ± 6 years old; 15 female, mean age 68.5 ± 3.8 years old and 31 male, mean age 71.5 ± 6.7 years old) with unilateral or bilateral ICA occlusion. In all patients, a Doppler ultrasound (DUS) examination, measuring blood flow volume in the internal carotid artery (ICA), external carotid artery (ECA), and vertebral artery (VA), was performed. The cerebral blood flow (CBF) was compared to the previously reported CBF values in the healthy population >65 years old. (3) Results: In comparison with CBF values in the healthy population, three subgroups with CBF changes were identified among patients with ICA occlusion: patients with significant volumetric flow compensation (CBF higher than average + standard deviation for healthy population of the same age), patients with flow similar to the healthy population (average ± standard deviation), and patients without compensation (CBF lower than the average-standard deviation for healthy population). The percentage of patients with significant volumetric flow compensation tend to rise with increasing age, while a simultaneous decline was observed in the group without compensation. The percentage of patients with flow similar to the healthy population remained relatively unchanged. ICA played the most important role in volumetric flow compensation in patients with CAO; however, the relative increase in flow in the ICA was smaller than that in the ECA and VA. Compensatory increased flow was observed in about 50% of all patent extracranial arteries and was more frequently observed in ipsilateral vessels than in contralateral ones, in both the ECA and the VA. In patients with CAO, there was no decrease in CBF, ICA, ECA, and VA flow volume with increasing age. (4) Conclusions: Volumetric flow compensation may play an important predictive role in patients with CAO.

Stentrievers : An engineering review.

The advent of endovascular therapy for acute large vessel occlusion has revolutionized stroke treatment. Timely access to endovascular therapy, and the ability to restore intracranial flow in a safe, efficient, and efficacious manner has been critical to the success of the thrombectomy procedure. The stentriever has been a mainstay of endovascular stroke therapy, and current guidelines recommend the usage of stentrievers in the treatment of large vessel occlusion stroke. Despite the success of existing stentrievers, there continues to be significant development in the field, with newer stentrievers attempting to improve on each of the three key aspects of the thrombectomy procedure. Here, we elucidate the technical requirements that a stentriever must fulfill. We then review the basic variables of stent design, including the raw material and its form, fabrication method, geometric configuration, and further additions. Lastly, a selection of stentrievers from successive generations are reviewed using these engineering parameters, and clinical data is presented. Further avenues of stentriever development and testing are also presented.

Flow Diverter Reconstruction of Internal Carotid Artery (Loop) Dissections with or without Associated Pseudoaneurysms

Endovascular treatment of cervical internal carotid artery (ICA) loop dissections in acute stroke interventions can be challenging. Flow diverters can effectively reconstruct vessel loops and treat the injured vessel and provide a safe conduit for intracranial catheterization. We retrospectively reviewed our neurointerventional database and identified all patients with ICA loop dissections treated with flow diverters in the acute setting between August 2016 and September 2020. Patient demographics, procedural data, imaging follow-up results, and clinical outcome information were collected. Seven patients with a mean age of 62 years (range: 43-85 years) who underwent reconstruction of an ICA (loop) dissection with flow diverters were included. Four ICA dissections were treated with the Surpass Streamline flow diverter and 3 with the Pipeline embolization device. All cases were technically successful. All stroke cases achieved intracranial flow ≥thrombolysis in cerebral infarction 2B. Observed intracranial hemorrhages were all asymptomatic. All cases showed patent flow diverter(s) with or without (carotid) stent(s) on follow-up imaging. Semielectively treated patients did not show a change from baseline modified Rankin scale related to the procedure. Patients with acute stroke had a modified Rankin scale ≤2 in 4 of 5 cases (80%) at 3 months. Two patients died due to medical issues unrelated to the procedures. No patient showed new or recurrent symptoms. Use of flow diverters, in some cases in conjunction with (carotid) stents, is an effective treatment option for cervical carotid artery (loop) dissections.