In Premature Newborns Intraventricular Hemorrhage Causes Cerebral Vasospasm and Associated Neurodisability via Heme-Induced Inflammasome-Mediated Interleukin-1 Production and Nitric Oxide Depletion

Vasospasm in Pediatric Subarachnoid Hemorrhage

Cerebral vasospasm (CV) is a common severe complication of subarachnoid hemorrhage (SAH), a severe type of intracranial bleeding that is uncommon in children. The purpose of this article is to review the current literature regarding this potentially devastating complication. CV may be asymptomatic and is less common in children compared to adults. Several molecular phenomena, including inflammatory ones, contribute to its pathophysiology. Better collateral circulation and higher cerebral blood flow are protective factors in children. When clinically apparent, CV may manifest as a change in the child's neurologic status or vital signs. CV can be diagnosed using brain vessel imaging, such as computed tomography angiography, magnetic resonance angiography, digital subtraction angiography, transcranial Doppler ultrasonography, and computed tomography perfusion. A reduction of < 50% in the artery's caliber confirms the diagnosis. Besides general supportive measures and causative treatment of SAH, CV management options include the administration of calcium channel blockers and neurointerventional approaches, such as intra-arterial vasodilators and balloon angioplasty. Long-term outcomes in children are usually favorable.

Deep cerebral venous abnormalities in premature babies with GMH-IVH: a single-centre retrospective study

PURPOSE

Germinal matrix haemorrhage/intraventricular haemorrhage (GMH-IVH) is a multifactorial injury with both anatomic and haemodynamic involvement. Normal variants in preterm deep cerebral venous anatomy associated with GMH-IVH have been previously described using MRI susceptibility weighted imaging (SWI). The aims of this study were to use SWI to compare the deep venous systems of a cohort of preterm neonates with various grades of GMH-IVH to a group of age-matched controls without GMH-IVH and to present novel retrospective SWI imaging findings.

METHODS

A neuroradiologist retrospectively evaluated 3T MRI SWI and phase imaging of 56 preterm neonates with GMH-IVH (14 of each grade) and 27 controls without GMH-IVH, scoring the venous irregularities according to three variables: decreased venous patency, increased lumen susceptibility and the presence of collaterals. Eight different venous locations, including indicated bilateral components, were evaluated: straight sinus, vein of galen, internal cerebral, direct lateral, thalamostriate, atrial and the anterior septal veins. Variables were analysed for statistical significance. Inter-rater reliability was determined via subset evaluation by a second paediatric radiologist.

RESULTS

Deep venous abnormalities were significantly more common in patients with GMH-IVH, with Wilcoxon Rank Sum Test demonstrating significant increase with GMH-IVH for total decreased venous patency (W=0, p<0.0001), increased lumen susceptibility and collateral formation. Venous abnormalities were also positively correlated with an increase in GMH-IVH grade from I to IV (patency, ρ=0.782, p<0.01) (increased lumen susceptibility, ρ=0.739, p<0.01) (collaterals, ρ=0.649, p<0.01), not just GMH-IVH alone.

CONCLUSION

Deep venous abnormalities are significantly correlated with GMH-IVH alone and an increase in GMH-IVH grade. Further study is needed to determine cause and effect.

Posthemorrhagic ventricular dilatation late intervention threshold and associated brain injury

OBJECTIVE

To systematically assess white matter injury (WMI) in preterm infants with posthemorrhagic ventricular dilatation (PHVD) using a high-threshold intervention strategy.

STUDY DESIGN

This retrospective analysis included 85 preterm infants (≤34 weeks of gestation) with grade 2-3 germinal matrix-intraventricular hemorrhage. Cranial ultrasound (cUS) scans were assessed for WMI and ventricular width and shape. Forty-eight infants developed PHVD, 21 of whom (intervention group) underwent cerebrospinal fluid drainage according to a predefined threshold (ventricular index ≥p97+4 mm or anterior horn width >10 mm, and the presence of frontal horn ballooning). The other 27 infants underwent a conservative approach (non-intervention group). The two PHVD groups were compared regarding ventricular width at two stages: the worst cUS for the non-intervention group (scans showing the largest ventricular measurements) versus pre-intervention cUS in the intervention group, and at term equivalent age. WMI was classified as normal/mild, moderate and severe.

RESULTS

The intervention group showed significantly larger ventricular index, anterior horn width and thalamo-occipital diameter than the non-intervention group at the two timepoints. Moderate and severe WMI were more frequent in the infants with PHVD (p<0.001), regardless of management (intervention or conservative management). There was a linear relationship between the severity of PHVD and WMI (p<0.001).

CONCLUSIONS

Preterm infants with PHVD who undergo a high-threshold intervention strategy associate an increased risk of WMI.

The role of blood product removal in intraventricular hemorrhage of prematurity: a meta-analysis of the clinical evidence

INTRODUCTION

Premature neonates have a high risk of intraventricular hemorrhage (IVH) at birth, the blood products of which activate inflammatory cascades that can cause hydrocephalus and long-term neurological morbidities and sequelae. However, there is no consensus for one treatment strategy. While the mainstay of treatment involves CSF diversion to reduce intracranial pressure, a number of interventions focus on blood product removal at various stages including extraventricular drains (EVD), intra-ventricular thrombolytics, drainage-irrigation-fibrinolytic therapy (DRIFT), and neuroendoscopic lavage (NEL).

METHODS

We performed a systematic review and meta-analysis to compare the risks and benefits commonly associated with active blood product removal treatment strategies. We searched MEDLINE, Embase, Scopus, Cochrane Library, and CINAHL databases through Dec 2020 for articles reporting on outcomes of EVDs, thrombolytics, DRIFT, and NEL. Outcomes of interest were rate of conversion to ventriculoperitoneal shunt (VPS), infection, mortality, secondary hemorrhage, and cognitive disability.

RESULTS

Of the 10,398 articles identified in the search, 23 full-text articles representing 22 cohorts and 530 patients were included for meta-analysis. These articles included retrospective, prospective, and randomized controlled studies on the use of EVDs (n = 7), thrombolytics (n = 8), DRIFT therapy (n = 3), and NEL (n = 5). Pooled rates of reported outcomes for EVD, thrombolytics, DRIFT, and NEL for ventriculoperitoneal shunt (VPS) placement were 51.1%, 43.3%, 34.3%, and 54.8%; for infection, 15.4%, 12.5%, 4.7%, and 11.0%; for mortality, 20.0%, 11.6%, 6.0%, and 4.9%; for secondary hemorrhage, 5.8%, 7.8%, 20.0%, and 6.9%; for cognitive impairment, 52.6%, 50.0%, 53.7%, and 50.9%. Meta-regression using type of treatment as a categorical covariate showed no effect of treatment modality on rate of VPS conversion or cognitive disability.

CONCLUSION

There was a significant effect of treatment modality on secondary hemorrhage and mortality; however, mortality was no longer significant after adjusting for year of publication. Re-hemorrhage rate was significantly higher for DRIFT (p < 0.001) but did not differ among the other modalities. NEL also had lower mortality relative to EVD (p < 0.001) and thrombolytics (p = 0.013), which was no longer significant after adjusting for year of publication. Thus, NEL appears to be safer than DRIFT in terms of risk of hemorrhage, and not different than other blood-product removal strategies in terms of mortality. Outcomes-in terms of shunting and cognitive impairment-did not differ. Later year of publication was predictive of lower rates of mortality, but not the other outcome variables. Further prospective and randomized studies will be necessary to directly compare NEL with other temporizing procedures.

Hydrocephalus Revisited: New Insights into Dynamics of Neurofluids on Macro- and Microscales

New experimental and clinical findings question the historic view of hydrocephalus and its 100-year-old classification. In particular, real-time magnetic resonance imaging (MRI) evaluation of cerebrospinal fluid (CSF) flow and detailed insights into brain water regulation on the molecular scale indicate the existence of at least three main mechanisms that determine the dynamics of neurofluids: (1) inspiration is a major driving force; (2) adequate filling of brain ventricles by balanced CSF upsurge is sensed by cilia; and (3) the perivascular glial network connects the ependymal surface to the pericapillary Virchow-Robin spaces. Hitherto, these aspects have not been considered a common physiologic framework, improving knowledge and therapy for severe disorders of normal-pressure and posthemorrhagic hydrocephalus, spontaneous intracranial hypotension, and spaceflight disease.

Neurofluids-Deep inspiration, cilia and preloading of the astrocytic network

With the advent of real-time MRI, the motion and passage of cerebrospinal fluid can be visualized without gating and exclusion of low-frequency waves. This imaging modality gives insights into low-volume, rapidly oscillating cardiac-driven movement as well as sustained, high-volume, slowly oscillating inspiration-driven movement. Inspiration means a spontaneous or artificial increase in the intrathoracic dimensions independent of body position. Alterations in thoracic diameter enable the thoracic and spinal epidural venous compartments to be emptied and filled, producing an upward surge of cerebrospinal fluid inside the spine during inspiration; this surge counterbalances the downward pooling of venous blood toward the heart. Real-time MRI, as a macroscale in vivo observation method, could expand our knowledge of neurofluid dynamics, including how astrocytic fluid preloading is adjusted and how brain buoyancy and turgor are maintained in different postures and zero gravity. Along with these macroscale findings, new microscale insights into aquaporin-mediated fluid transfer, its sensing by cilia, and its tuning by nitric oxide will be reviewed. By incorporating clinical knowledge spanning several disciplines, certain disorders-congenital hydrocephalus with Chiari malformation, idiopathic intracranial hypertension, and adult idiopathic hydrocephalus-are interpreted and reviewed according to current concepts, from the basics of the interrelated systems to their pathology.

Delayed Cerebral Ischemia of the Corpus Callosum: A Case Report

Ischemic infarction of the corpus callosum is a rare condition due to its rich vascular supply and therefore has been infrequently reported. Here, we present a case of a patient who developed a delayed infarct of the corpus callosum in the body. The condition was characterized by bilateral lower extremity weakness and visual disturbances following intraventricular hemorrhage managed with ventriculostomy. Understanding the anatomy and function of the corpus callosum is crucial to understanding the etiology of infarctions as well as their clinical significance. It is also essential to distinguish between relatively common post-shunting changes and true infarction and to recognize the limited consequences of corpus callosum infarction. Increased awareness of this rare infarct would help to prevent unnecessary interventions and increase the ability of the physician to provide optimal care for the patient.

Evidence Supporting the Hypothesis That Inflammation-Induced Vasospasm Is Involved in the Pathogenesis of Acquired Sensorineural Hearing Loss

Sensorineural hearing loss is mainly acquired and affects an estimated 1.3 billion humans worldwide. It is related to aging, noise, infection, ototoxic drugs, and genetic defects. It is essential to identify reversible and preventable causes to be able to reduce the burden of this disease. Inflammation is involved in most causes and leads to tissue injury through vasospasm-associated ischemia. Vasospasm is reversible. This review summarized evidence linking inflammation-induced vasospasm to several forms of acquired sensorineural hearing loss. The link between vasospasm and sensorineural hearing loss is directly evident in subarachnoid haemorrhage, which involves the release of vasoconstriction-inducing cytokines like interleukin-1, endothelin-1, and tumour necrosis factor. These proinflammatory cytokines can also be released in response to infection, autoimmune disease, and acute or chronically increased inflammation in the ageing organism as in presbyacusis or in noise-induced cochlear injury. Evidence of vasospasm and hearing loss has also been discovered in bacterial meningitis and brain injury. Resolution of inflammation-induced vasospasm has been associated with improvement of hearing in autoimmune diseases involving overproduction of interleukin-1 from inflammasomes. There is mainly indirect evidence for vasospasm-associated sensorineural hearing loss in most forms of systemic or injury- or infection-induced local vascular inflammation. This opens up avenues in prevention and treatment of vascular and systemic inflammation as well as vasospasm itself as a way to prevent and treat most forms of acquired sensorineural hearing loss. Future research needs to investigate interventions antagonising vasospasm and vasospasm-inducing proinflammatory cytokines and their production in randomised controlled trials of prevention and treatment of acquired sensorineural hearing loss. Prime candidates for interventions are hereby inflammasome inhibitors and vasospasm-reducing drugs like nitric oxide donors, rho-kinase inhibitors, and magnesium which have the potential to reduce sensorineural hearing loss in meningitis, exposure to noise, brain injury, arteriosclerosis, and advanced age-related and autoimmune disease-related inflammation.

Protocatechuic acid exerts protective effects via suppression of the P38/JNK- NF-κB signalling pathway in an experimental mouse model of intracerebral haemorrhage

Protocatechuic acid (PCA) has been well studied for its neuroprotection value in several diseases, but the effect in intracerebral haemorrhage (ICH) has not been reported. Here we verified the protection of PCA in ICH, and investigated the relative mechanisms. ICH model mice were established by injection of collagenase IV. The mice were treated with PCA once per day for 3 days, starting immediately after operation. The modified neurological severity score (mNSS) of mice at 1st, 3rd and 7th day after operation were recorded. And some of mice were euthanized at 3rd day to compare brain water content, pro-inflammatory cytokines expression, and cell apoptosis in perihematomal tissue. Additionally, SH-SY5Y cells were treated hemin to mimic secondary injury of ICH. Cells were incubated with PCA for treatment. The cell viability, ROS, apoptosis rate and protein expression of apoptosis-relative protein and MAPKs and NF-κB were detected and analysed. The results revealed PCA alleviated the cerebral oedema at 3rd post ICH, and significantly improved neurological functions. PCA also attenuated the protein and gene expression of TNF-а, IL-1β and IL-6 vivo. PCA dose-dependently decreased the generation of ROS and apoptosis rate. Furthermore, PCA treatment dose-dependently decreased the expression of bax, cleaved caspase-3, increased bcl-2 expression; PCA downregulated P38/JNK-NF-κB pathway. In conclusion, PCA effectively improves prognosis of ICH mice by inhibiting oxidative stress, inflammation and apoptosis. The mechanism possibly results of downregulating of P38/JNK-NF-κB pathway, and PCA can be a potential therapeutic agent for ICH.