Neuropathological changes caused by hydrocephalus

Microcirculatory Impairment and Cerebral Injury in Hydrocephalus and the Effects of Cerebrospinal Fluid Diversion

BACKGROUND AND OBJECTIVES

Hydrocephalus is characterized by progressive enlargement of cerebral ventricles, resulting in impaired microvasculature and cerebral hypoperfusion. This study aimed to demonstrate the microvascular changes in hydrocephalic rats and the effects of cerebrospinal fluid (CSF) release on cerebral blood flow (CBF).

METHODS

On postnatal day 21 (P21), male Wistar rats were intracisternally injected with either a kaolin suspension or saline. On P47, Evan's ratio (ER) was measured using MRI. On P49, the arteriolar diameter and vascular density of the pia were quantified using a capillary video microscope. The CBF was measured using laser Doppler flowmetry. The expressions of NeuN and glial fibrillary acidic protein determined by immunochemical staining were correlated with the ER. The CBF and rotarod test performance were recorded before and after CSF release. The expressions of 4-hydroxynonenal (4-HNE) and c-caspase-3 were studied on P56.

RESULTS

Ventriculomegaly was induced to varying degrees, resulting in the stretching and abnormal narrowing of pial arterioles, which regressed with increasing ER. Quantitative analysis revealed significant decreases in the arteriolar diameter and vascular density in the hydrocephalic group compared with those in the control group. In addition, the CBF in the hydrocephalic group decreased to 30%-50% of that in the control group. In hydrocephalus, the neurons appear distorted, and the expression of 4-HNE and reactive astrogliosis increase in the cortex. After CSF was released, improvements in the CBF and rotarod test performance were inversely associated with the ER. In addition, the levels of 4-HNE and c-caspase-3 were further elevated.

CONCLUSION

Rapid ventricular dilatation is associated with severe microvascular distortion, vascular regression, cortical hypoperfusion, and cellular changes that impair the recovery of CBF and motor function after CSF release. Moreover, CSF release may induce reperfusion injury. This pathophysiology should be taken into account when treating hydrocephalus.

Regulation of brain fluid volumes and pressures: basic principles, intracranial hypertension, ventriculomegaly and hydrocephalus

The principles of cerebrospinal fluid (CSF) production, circulation and outflow and regulation of fluid volumes and pressures in the normal brain are summarised. Abnormalities in these aspects in intracranial hypertension, ventriculomegaly and hydrocephalus are discussed. The brain parenchyma has a cellular framework with interstitial fluid (ISF) in the intervening spaces. Framework stress and interstitial fluid pressure (ISFP) combined provide the total stress which, after allowing for gravity, normally equals intracerebral pressure (ICP) with gradients of total stress too small to measure. Fluid pressure may differ from ICP in the parenchyma and collapsed subarachnoid spaces when the parenchyma presses against the meninges. Fluid pressure gradients determine fluid movements. In adults, restricting CSF outflow from subarachnoid spaces produces intracranial hypertension which, when CSF volumes change very little, is called idiopathic intracranial hypertension (iIH). Raised ICP in iIH is accompanied by increased venous sinus pressure, though which is cause and which effect is unclear. In infants with growing skulls, restriction in outflow leads to increased head and CSF volumes. In adults, ventriculomegaly can arise due to cerebral atrophy or, in hydrocephalus, to obstructions to intracranial CSF flow. In non-communicating hydrocephalus, flow through or out of the ventricles is somehow obstructed, whereas in communicating hydrocephalus, the obstruction is somewhere between the cisterna magna and cranial sites of outflow. When normal outflow routes are obstructed, continued CSF production in the ventricles may be partially balanced by outflow through the parenchyma via an oedematous periventricular layer and perivascular spaces. In adults, secondary hydrocephalus with raised ICP results from obvious obstructions to flow. By contrast, with the more subtly obstructed flow seen in normal pressure hydrocephalus (NPH), fluid pressure must be reduced elsewhere, e.g. in some subarachnoid spaces. In idiopathic NPH, where ventriculomegaly is accompanied by gait disturbance, dementia and/or urinary incontinence, the functional deficits can sometimes be reversed by shunting or third ventriculostomy. Parenchymal shrinkage is irreversible in late stage hydrocephalus with cellular framework loss but may not occur in early stages, whether by exclusion of fluid or otherwise. Further studies that are needed to explain the development of hydrocephalus are outlined.

The Cerebral Aqueduct Compliance: A Simple Morphometric Model

BACKGROUND AND OBJECTIVES

This work aimed to identify different configurations of the adytum of the cerebral aqueduct suggesting its safe neuroendoscopic navigation. This concept is intimately connected to the physiological aqueductal dilatability or compliance, which is relatively ignored in the literature. A better knowledge of the extent of physiological aqueductal dilatability might better define the ideal diameter and safer features of dedicated flexible endoscopes.

METHODS

The study includes 45 patients operated on using a flexible scope with a 3.9-mm diameter, where the structural elements of the adytum of the cerebral aqueduct are clearly visible. Patients were grouped according to the pathology (colloid cyst/normal anatomy, intraventricular hemorrhage, tetraventricular obstructive hydrocephalus, normal pressure hydrocephalus, and distal membranous aqueductal stenosis). A simple geometrical scheme was applied to the endoscopic anatomy of the aqueductal adytum in relation to the posterior commissure to measure its pathologic deformations. Eventual damages to the aqueduct walls caused by the endoscope were also reported.

RESULTS

Proceeding from normal anatomy to hydrocephalic condition, the ratio between the commissure and the aqueductal access area progressively decreases, while the vertex angle increases. Interestingly, the entity of the ependymal damages due to the passage of the endoscope correlates with such measures.

CONCLUSION

The cerebral aqueduct, excluding atrophic processes, is provided with a certain degree of dilatability, which we estimate to be around a diameter of 4 mm. This represents the maximum size for a flexible neuroendoscope for a safe aqueductal neuronavigation. The schematic model of the aqueductal adytum as a triangle defines 3 different aqueductal patterns and can be helpful when an intraoperative decision on whether to navigate the aqueduct must be taken.

Association of Glymphatic and White Matter Impairment With the Postoperative Outcome of Pediatric Hydrocephalus

BACKGROUND AND OBJECTIVES

Assessment of postoperative outcomes on pediatric hydrocephalus is critical for adjusting treatment strategies. The aim of this work was to investigate the ability of MRI metrics to predict postoperative outcomes.

METHODS

A total of 55 children with hydrocephalus who underwent MRI and ventriculoperitoneal shunt surgery were prospectively enrolled. MRI was also performed at 6 months postoperatively in 33 of the 55 children. A total of 92 controls matched for age and sex were enrolled and divided into preoperative and postoperative control groups. We calculated the diffusion tensor imaging along the perivascular space (DTI-ALPS) index, Evans index, and diffusion tensor imaging metrics. The ability of various metrics to predict postoperative outcomes was assessed using receiver operating characteristic curve analysis.

RESULTS

The DTI-ALPS index was significantly lower in patients with hydrocephalus than in controls. The abnormal DTI-ALPS index trended toward the normal range after surgery. Patients with lower preoperative DTI-ALPS index, lower fractional anisotropy (FA), and higher radial diffusivity in association fibers had less favorable short-term outcomes. Patients with worse long-term outcomes had lower postoperative DTI-ALPS index, higher postoperative Evans index, and lower FA and higher radial diffusivity in association fibers. Predictive performance was better when the DTI-ALPS index and FA in association fibers were used in combination than when either of these metrics was used alone.

CONCLUSION

The DTI-ALPS index and FA in association fibers provided complementary information for prognostic assessment after the ventriculoperitoneal shunt surgery on pediatric hydrocephalus. A combination of DTI-ALPS index and FA would improve our ability to predict postoperative outcomes in these patients.

Machine learning in prenatal MRI predicts postnatal ventricular abnormalities in fetuses with isolated ventriculomegaly

OBJECTIVES

To evaluate the intracranial structures and brain parenchyma radiomics surrounding the occipital horn of the lateral ventricle in normal fetuses (NFs) and fetuses with ventriculomegaly (FVs), as well as to predict postnatally enlarged lateral ventricle alterations in FVs.

METHODS

Between January 2014 and August 2023, 141 NFs and 101 FVs underwent 1.5 T balanced steady-state free precession (BSSFP), including 68 FVs with resolved lateral ventricles (FVM-resolved) and 33 FVs with stable lateral ventricles (FVM-stable). Demographic data and intracranial structures were analyzed. To predict the enlarged ventricle alterations of FVs postnatally, logistic regression models with 5-fold cross-validation were developed based on lateral ventricle morphology, blended-cortical or/and subcortical radiomics characteristics. Validation of the models' performance was conducted using the receiver operating characteristic curve (ROC), calibration curve, and decision curve analysis (DCA).

RESULTS

Significant alterations in cerebral structures were observed between NFs and FVs (p < 0.05), excluding the maximum frontal horn diameter (FD). However, there was no notable distinction between the FVM-resolved and FVM-stable groups (all p > 0.05). Based on subcortical-radiomics on the aberrant sides of FVs, this approach exhibited high efficacy in distinguishing NFs from FVs in the training/validation set, yielding an impressive AUC of 1/0.992. With an AUC value of 0.822/0.743 in the training/validation set, the Subcortical-radiomics model demonstrated its ability to predict lateral ventricle alterations in FVs, which had the greatest predictive advantages indicated by DCA.

CONCLUSIONS

Microstructural alterations in subcortical parenchyma associated with ventriculomegaly can serve as predictive indicators for postnatal lateral ventricle variations in FVs.

CLINICAL RELEVANCE STATEMENT

It is critical to gain pertinent information from a solitary fetal MRI to anticipate postnatal lateral ventricle alterations in fetuses with ventriculomegaly. This approach holds the potential to diminish the necessity for recurrent prenatal ultrasound or MRI examinations.

KEY POINTS

Fetal ventriculomegaly is a dynamic condition that affects postnatal neurodevelopment. Machine learning and subcortical-radiomics can predict postnatal alterations in the lateral ventricle. Machine learning, applied to single-fetal MRI, might reduce required antenatal testing.

Loss of Katnal2 leads to ependymal ciliary hyperfunction and autism-related phenotypes in mice

Autism spectrum disorders (ASD) frequently accompany macrocephaly, which often involves hydrocephalic enlargement of brain ventricles. Katnal2 is a microtubule-regulatory protein strongly linked to ASD, but it remains unclear whether Katnal2 knockout (KO) in mice leads to microtubule- and ASD-related molecular, synaptic, brain, and behavioral phenotypes. We found that Katnal2-KO mice display ASD-like social communication deficits and age-dependent progressive ventricular enlargements. The latter involves increased length and beating frequency of motile cilia on ependymal cells lining ventricles. Katnal2-KO hippocampal neurons surrounded by enlarged lateral ventricles show progressive synaptic deficits that correlate with ASD-like transcriptomic changes involving synaptic gene down-regulation. Importantly, early postnatal Katnal2 re-expression prevents ciliary, ventricular, and behavioral phenotypes in Katnal2-KO adults, suggesting a causal relationship and a potential treatment. Therefore, Katnal2 negatively regulates ependymal ciliary function and its deletion in mice leads to ependymal ciliary hyperfunction and hydrocephalus accompanying ASD-related behavioral, synaptic, and transcriptomic changes.

Noradrenergic Pathways Involved in Micturition in an Animal Model of Hydrocephalus-Implications for Urinary Dysfunction

Hydrocephalus is characterized by enlargement of the cerebral ventricles, accompanied by distortion of the periventricular tissue. Patients with hydrocephalus usually experience urinary impairments. Although the underlying etiology is not fully described, the effects of hydrocephalus in the neuronal network responsible for the control of urination, which involves periventricular areas, including the periaqueductal gray (PAG) and the noradrenergic locus coeruleus (LC). In this study, we aimed to investigate the mechanisms behind urinary dysfunction in rats with kaolin-induced hydrocephalus. For that purpose, we used a validated model of hydrocephalus-the rat injected with kaolin in the cisterna magna-also presents urinary impairments in order to investigate the putative involvement of noradrenergic control from the brain to the spinal cord Onuf's nucleus, a key area in the motor control of micturition. We first evaluated bladder contraction capacity using cystometry. Since our previous characterization of the LC in hydrocephalic animals showed increased levels of noradrenaline, we then evaluated the noradrenergic innervation of the spinal cord's Onuf's nucleus by measuring levels of dopamine β-hydroxylase (DBH). We also evaluated the expression of the c-Fos protooncogene, the most widely used marker of neuronal activation, in the ventrolateral PAG (vlPAG), an area that plays a major role in the control of urination by its indirect control of the LC via pontine micturition center. Hydrocephalic rats showed an increased frequency of bladder contractions and lower minimum pressure. These animals also presented increased DBH levels at the Onuf´s nucleus, along with decreased c-Fos expression in the vlPAG. The present findings suggest that impairments in urinary function during hydrocephalus may be due to alterations in descending noradrenergic modulation. We propose that the effects of hydrocephalus in the decrease of vlPAG neuronal activation lead to a decrease in the control over the LC. The increased availability of noradrenaline production at the LC probably causes an exaggerated micturition reflex due to the increased innervation of the Onuf´s nucleus, accounting for the urinary impairments detected in hydrocephalic animals. The results of the study provide new insights into the neuronal underlying mechanisms of urinary dysfunction in hydrocephalus. Further research is needed to fully evaluate the translational perspectives of the current findings.

History of research concerning the ependyma: a view from inside the human brain

The history of research concerning ependymal cells is reviewed. Cilia were identified along the surface of the cerebral ventricles c1835. Numerous anatomical and histopathological studies in the late 1800's showed irregularities in the ependymal surface that were thought to be indicative of specific pathologies such as syphilis; this was subsequently disproven. The evolution of thoughts about functions of cilia, the possible role of ependyma in the brain-cerebrospinal fluid barrier, and the relationship of ependyma to the subventricular zone germinal cells is discussed. How advances in light and electron microscopy and cell culture contributed to our understanding of the ependyma is described. Discoveries of the supraependymal serotoninergic axon network and supraependymal macrophages are recounted. Finally, the consequences of loss of ependymal cells from different regions of the central nervous system are considered.

Brain blood flow pulse analysis may help to recognize individuals who suffer from hydrocephalus

BACKGROUND

Normal pressure hydrocephalus (NPH) is often associated with altered cerebral blood flow. Recent research with the use of the ultrasonic method suggests specific changes in the shape of cardiac-related cerebral arterial blood volume (CaBV) pulses in NPH patients. Our study aims to provide a quantitative analysis of the shape of CaBV pulses, estimated based on transcranial Doppler ultrasonography (TCD) in NPH patients and healthy individuals.

METHODS

The CaBV pulses were estimated using TCD cerebral blood flow velocity signals recorded from probable NPH adults and age-matched healthy individuals at rest. The shape of the CaBV pulses was compared to a triangular shape with 27 similarity parameters calculated for every reliable CaBV pulse and compared between patients and volunteers. The diagnostic accuracy of the most prominent parameter for NPH classification was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

The similarity parameters were calculated for 31 probable NPH patients (age: 59 years (IQR: 47, 67 years), 14 females) and 23 healthy volunteers (age: 54 years (IQR: 43, 61 years), 18 females). Eighteen of 27 parameters were different between healthy individuals and NPH patients (p < 0.05). The most prominent differences were found for the ascending slope of the CaBV pulse with the AUC equal to 0.87 (95% confidence interval: 0.77, 0.97, p < 0.001).

CONCLUSIONS

The findings suggest that in NPH, the ascending slope of the CaBV pulse had a slower rise, was more like a straight line, and generally was less convex than in volunteers. Prospective research is required to verify the clinical utility of these findings.

Impact of Spina Bifida on Sleep Quality: Current Insights

Spina bifida (SB) is one of the most common birth defects in children. The care for patients with SB continues to evolve, and there has been notable improvement in survival outcomes, degree of disability and quality of life for these children. However, patients with SB continue to remain at higher risk for sleep-related breathing disorders (SRBD), unexplained sudden death, and potential alterations in their sleep chronotype. Previous studies report on abnormalities in the spinal cord, brainstem function, and dysfunction of upper airway maintenance as the likely mechanisms behind SRBD that is commonly seen in SB. Most studies looking at prevalence of SRBD in SB have been retrospective studies. A recent prospective study identified a prevalence as high as 42% when a polysomnography (PSG) was completed on all patients regardless of symptomatology. Treatment options vary depending on the type and severity of SRBD and can range widely. Despite advances in care for patients with SB and SRBD, a subset of these patients with myelomeningocele (MMC) continue to experience sudden unexplained death. Studies continue to evaluate ways to stratify which of these patients may be at higher risk of this devastating outcome. Given that SRBD is potentially treatable, early assessment and intervention could become an integral part of a multidisciplinary treatment strategy to optimize long-term medical and neurodevelopmental outcomes for this patient population. By understanding the impact that SB may have on a patient's sleep quality, their biological chronotype and their potential of developing SRBD, a provider may help to optimize the care a patient with SB receives from birth into adulthood.

Therapeutic strategies to recover ependymal barrier after inflammatory damage: relevance for recovering neurogenesis during development

The epithelium covering the surfaces of the cerebral ventricular system is known as the ependyma, and is essential for maintaining the physical and functional integrity of the central nervous system. Additionally, the ependyma plays an essential role in neurogenesis, neuroinflammatory modulation and neurodegenerative diseases. Ependyma barrier is severely affected by perinatal hemorrhages and infections that cross the blood brain barrier. The recovery and regeneration of ependyma after damage are key to stabilizing neuroinflammatory and neurodegenerative processes that are critical during early postnatal ages. Unfortunately, there are no effective therapies to regenerate this tissue in human patients. Here, the roles of the ependymal barrier in the context of neurogenesis and homeostasis are reviewed, and future research lines for development of actual therapeutic strategies are discussed.

A neural stem cell paradigm of pediatric hydrocephalus

Pediatric hydrocephalus, the leading reason for brain surgery in children, is characterized by enlargement of the cerebral ventricles classically attributed to cerebrospinal fluid (CSF) overaccumulation. Neurosurgical shunting to reduce CSF volume is the default treatment that intends to reinstate normal CSF homeostasis, yet neurodevelopmental disability often persists in hydrocephalic children despite optimal surgical management. Here, we discuss recent human genetic and animal model studies that are shifting the view of pediatric hydrocephalus from an impaired fluid plumbing model to a new paradigm of dysregulated neural stem cell (NSC) fate. NSCs are neuroprogenitor cells that comprise the germinal neuroepithelium lining the prenatal brain ventricles. We propose that heterogenous defects in the development of these cells converge to disrupt cerebrocortical morphogenesis, leading to abnormal brain-CSF biomechanical interactions that facilitate passive pooling of CSF and secondary ventricular distention. A significant subset of pediatric hydrocephalus may thus in fact be due to a developmental brain malformation leading to secondary enlargement of the ventricles rather than a primary defect of CSF circulation. If hydrocephalus is indeed a neuroradiographic presentation of an inborn brain defect, it suggests the need to focus on optimizing neurodevelopment, rather than CSF diversion, as the primary treatment strategy for these children.

Hydrocephalus: A neuropsychological and theoretical primer

Hydrocephalus is a common neurological condition, the hallmark feature of which is an excess in production, or accumulation, of cerebrospinal fluid in the ventricles. Although it is associated with diffuse damage to paraventricular brain areas, patients are broadly typified by a particular pattern of cognitive impairments that include deficits in working memory, attention, and spatial abilities. There have, however, been relatively few neuropsychological accounts of the condition. Moreover, theories of the relationship between aetiology and impairment appear to have emerged in isolation of each other, and proffer fundamentally different accounts. In this primer, we aim to provide a comprehensive and contemporary overview of hydrocephalus for the neuropsychologist, covering cognitive sequelae and theoretical interpretations of their origins. We review clinical and neuropsychological assays of cognitive profiles, along with the few studies that have addressed more integrative behaviours. In particular, we explore the distinction between congenital or early-onset hydrocephalus with a normal-pressure variant that can be acquired later in life. The relationship between these two populations is a singularly interesting one in neuropsychology since it can allow for the examination of typical and atypical developmental trajectories, and their interaction with chronic and acute impairment, within the same broad neurological condition. We reflect on the ramifications of this for our subject and suggest avenues for future research.

Tumor region associated with specific processing speed outcomes

OBJECTIVE

Processing speed (PS) is a vulnerable cognitive skill in pediatric cancer survivors as a consequence of treatments and, less consistently, tumor region. Studies conventionally examine graphomotor PS; emerging research suggests other aspects of PS may be impacted. This study examined types of PS in pediatric brain tumor survivors to determine which aspects are impaired. Given discordance across studies, we additionally investigated the relationship between brain region and PS.

METHODS

The sample consisted of 167 pediatric brain tumor patients (100 supratentorial). PS (oral naming, semantic fluency, phonemic fluency, motor speed, graphomotor speed, visual scanning) was gathered via clinical neuropsychological assessment. To examine PS by region, infratentorial and supratentorial groups were matched on age at diagnosis and neuropsychological assessment, and time since diagnosis.

RESULTS

The whole sample performed below normative means on measures of oral naming (p < .001), phonemic fluency (p < .001), motor speed (p = .03), visual scanning (p < .001), and graphomotor speed (p < .001). Only oral naming differed by region (p = .03), with infratentorial tumors associated with slower performance. After controlling for known medical and demographic risk factors, brain region remained a significant predictor of performance (p = .04). Among the whole sample, greater than expected proportions of patients with impairment (i.e., >1 standard deviation below the normative mean) were seen across all PS measures. Infratentorial tumors had higher rates of impairments across all PS measures except phonemic fluency.

CONCLUSIONS

Results indicate pediatric brain tumor survivors demonstrate weaknesses in multiple aspects of PS, suggesting impairments are not secondary to peripheral motor slowing alone. Additionally, tumor region may predict some but not all neuropsychological outcomes in this population.

MR Protocols for Paediatric Neurosurgical Common Conditions: An Update Guide for Neurosurgeons

The biggest challenge for clinicians and surgeons when it comes to radiological examinations is the ability to request the right modalities and to understand the strengths and limitations of each modality. This is particularly important in paediatric neurosciences where despite magnetic resonance imaging (MRI) being the main imaging modality, there are several protocols, technical limitations of specific scanners and issues related to sedation that need to be taken into account. In this chapter, we describe a simple approach for six common neurosurgical conditions to guide the paediatric neurosurgeons in requesting the right MR protocol and understanding the rationale of it.Paediatric neuro-oncology, epilepsy and neck/skull base protocols are discussed elsewhere in this book and therefore will not be a focus in this chapter (Bernasconi et al., Epilepsia 60:1054-68, 2019; D'Arco et al., Neuroradiology 64:1081-100; 2022; Avula et al., Childs Nerv Syst 37:2497-508; 2021).

Effect of comorbid Parkinson's disease and Parkinson's disease dementia on the course of idiopathic normal pressure hydrocephalus

OBJECTIVE

The objective of this study was to analyze the effect of concomitant Parkinson's disease (PD) and PD dementia (PD/PDD) on the course of idiopathic normal pressure hydrocephalus (iNPH), especially as related to the outcome of lumboperitoneal shunt (LPS) surgery.

METHODS

The authors retrospectively analyzed patients with iNPH without accompanying disorders (iNPH alone [iNPHa]) and iNPH concomitant with PD/PDD (iNPHc+PD/PDD) who had presented to their department between 2010 and 2019. The diagnosis of iNPHc+PD/PDD was established using the diagnostic criteria of the Movement Disorder Society. The effect of LPS surgery on clinical symptoms and striatum volumes was evaluated.

RESULTS

Thirty-three patients with iNPHa and 23 patients with iNPHc+PD/PDD were identified. Comorbid PD/PDD significantly worsened clinical outcome as measured by the iNPH grading scale, modified Rankin Scale (mRS), and Hoehn and Yahr (HY) scale. LPS surgery improved the iNPH score including gait disturbance (p < 0.01), cognitive impairment (p = 0.02), and urinary disturbance (p < 0.01) in iNPHa and improved gait disturbance (p = 0.01) and urinary disturbance (p = 0.03) in iNPHc+PD/PDD for 1 year. Comorbid synucleinopathies maintained worse mRS scores and HY stages for 3 years, and LPS surgery extended overall survival (p = 0.003), as well as the period of sustained mRS scores (p = 0.04) and HY stages (p = 0.004) in iNPHc+PD/PDD. Both caudate and putamen volumes were reduced in iNPHa (p < 0.01) compared to those in controls and in patients with iNPHc+PD/PDD compared to those in patients with PD/PDD (p < 0.01), and LPS surgery restored caudate volumes in both groups.

CONCLUSIONS

These results revealed that comorbid PD/PDD deteriorates the clinical course of iNPH and that LPS surgery is recommended regardless of this comorbidity.

Distinct cerebral cortical perfusion patterns in idiopathic normal-pressure hydrocephalus

The aims of the study are to evaluate idiopathic normal-pressure hydrocephalus (INPH)-related cerebral blood flow (CBF) abnormalities and to investigate their relation to cortical thickness in INPH patients. We investigated cortical CBF utilizing surface-based early-phase ¹⁸ F-florbetaben (E-FBB) PET analysis in two groups: INPH patients and healthy controls. All 39 INPH patients and 20 healthy controls were imaged with MRI, including three-dimensional volumetric images, for automated surface-based cortical thickness analysis across the entire brain. A subgroup with 37 participants (22 INPH patients and 15 healthy controls) that also underwent ¹⁸ F-fluorodeoxyglucose (FDG) PET imaging was further analyzed. Compared with age- and gender-matched healthy controls, INPH patients showed statistically significant hyperperfusion in the high convexity of the frontal and parietal cortical regions. Importantly, within the INPH group, increased perfusion correlated with cortical thickening in these regions. Additionally, significant hypoperfusion mainly in the ventrolateral frontal cortex, supramarginal gyrus, and temporal cortical regions was observed in the INPH group relative to the control group. However, this hypoperfusion was not associated with cortical thinning. A subgroup analysis of participants that also underwent FDG PET imaging showed that increased (or decreased) cerebral perfusion was associated with increased (or decreased) glucose metabolism in INPH. A distinctive regional relationship between cerebral cortical perfusion and cortical thickness was shown in INPH patients. Our findings suggest distinct pathophysiologic mechanisms of hyperperfusion and hypoperfusion in INPH patients.

A scoping review of cognition in spina bifida and its consequences for activity and participation throughout life

Aim

The aim of this scoping review was to summarise findings concerning cognitive characteristics in people with spina bifida and explain how cognitive factors influence activities and participation in different areas and stages of life.

Methods

PubMed, Psych INFO, ERIC, Scopus, CINAHL and the Cochrane Library were searched for English language papers published in 2000–2018. A total of 92 papers were selected and quality was assessed according to the McMaster criteria. The results were presented related to body functions, activity and participation from the International Classification of Function and Health, ICF.

Results

People with spina bifida tended to have a lower IQ than those without. The majority also had cognitive difficulties manifested in problems with language, perception, memory, executive and attentional functions. Those difficulties affected activity and participation in all life domains in ICF. This may affect medical adherence and responsibility and by extension the prevention of secondary complications.

Conclusion

It is important for caregivers, professionals and especially individuals with spina bifida themselves to understand and handle both physical and cognitive consequences in all life circumstances. Having insight into one’s own assets and difficulties paves the way to managing life challenges, which could enhance health, self‐management and participation in society.

Brain Network Connectivity and Executive Function in Children with Previous Infantile Hydrocephalus

INTRODUCTION

Infantile hydrocephalus is a condition in which there is an abnormal build-up of cerebrospinal fluid in the ventricles within the first few months of life, which puts pressure on surrounding brain tissues. Compression of the developing brain increases the risk of secondary brain injury and cognitive disabilities.

METHODS

In this study, we used diffusion-weighted imaging and resting-state functional MRI to investigate the effects of ventricle dilatation on structural and functional brain networks in children with shunted infantile hydrocephalus and examined how these brain changes may impact executive function.

RESULTS

We found that children with hydrocephalus have altered structural and functional connectivity between and within large-scale networks. Moreover, hyperconnectivity between the ventral attention and default mode network in children with hydrocephalus correlated with reduced executive function scores. Compared to typically developing age-matched control participants, our patient population also had lower fractional anisotropy in posterior white matter.

DISCUSSION

Overall, these findings suggest that infantile hydrocephalus has long-term effects on brain network connectivity, white matter development, and executive function in children at school-age. Future work will examine the relationship between ventricular volumes prior to shunt placement in infancy and brain network development throughout childhood.

Secondary Brain Injury Following Neonatal Intraventricular Hemorrhage: The Role of the Ciliated Ependyma

Intraventricular hemorrhage is recognized as a leading cause of hydrocephalus in the developed world and a key determinant of neurodevelopmental outcome following premature birth. Even in the absence of haemorrhagic infarction or posthaemorrhagic hydrocephalus, there is increasing evidence of neuropsychiatric and neurodevelopmental sequelae. The pathophysiology underlying this injury is thought to be due to a primary destructive and secondary developmental insult, but the exact mechanisms remain elusive and this has resulted in a paucity of therapeutic interventions. The presence of blood within the cerebrospinal fluid results in the loss of the delicate neurohumoral gradient within the developing brain, adversely impacting on the tightly regulated temporal and spatial control of cell proliferation and migration of the neural stem progenitor cells within the subventricular zone. In addition, haemolysis of the erythrocytes, associated with the release of clotting factors and leucocytes into the cerebrospinal (CSF), results in a toxic and inflammatory CSF microenvironment which is harmful to the periventricular tissues, resulting in damage and denudation of the multiciliated ependymal cells which line the choroid plexus and ventricular system. The ependyma plays a critical role in the developing brain and beyond, acting as both a protector and gatekeeper to the underlying parenchyma, controlling influx and efflux across the CSF to brain interstitial fluid interface. In this review I explore the hypothesis that damage and denudation of the ependymal layer at this critical juncture in the developing brain, seen following IVH, may adversely impact on the brain microenvironment, exposing the underlying periventricular tissues to toxic and inflammatory CSF, further exacerbating disordered activity within the subventricular zone (SVZ). By understanding the impact that intraventricular hemorrhage has on the microenvironment within the CSF, and the consequences that this has on the multiciliated ependymal cells which line the neuraxis, we can begin to develop and test novel therapeutic interventions to mitigate damage and reduce the associated morbidity.

Comorbid alpha synucleinopathies in idiopathic normal pressure hydrocephalus

OBJECTIVE

This study aimed to determine the prevalence and clinical features of Parkinson's disease (PD)/PD dementia (PD/PDD) or dementia with Lewy bodies (DLB) in idiopathic normal pressure hydrocephalus (iNPH).

METHODS

Patients with iNPH who were admitted to the Department of Neurology, Juntendo University School of Medicine over the past 10 years have been retrospectively analyzed. The diagnosis of iNPH and concomitant PD/PDD or DLB was established using diagnostic criteria. Motor symptoms were assessed by the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III. ¹²³I-ioflupane single-photon emission computed tomography (DaT-SPECT) and cerebrospinal fluid (CSF) real-time quaking-induced conversion (RT-QuIC)-based assay were performed for alpha synuclein aggregation.

RESULTS

Overall, 79 patients met the criteria for iNPH, of which 34 developed iNPH without accompanying disorders (iNPHa; 43%), 23 developed iNPH with comorbid PD/PDD (iNPHc + PD/PDD; 29.1%), and 8 developed iNPH with comorbid DLB (iNPHc + DLB; 10.1%). Significant differences in facial expansion and upper-limb parkinsonism were observed with a comorbidity of either PD/PDD or DLB. The specific binding ratio (SBR) of DaTscan was reduced in iNPHa (p = 0.02), but it reduced further with comorbid PD/PDD (p < 0.01) or DLB (p < 0.01). RT-QuIC was positive for all 13 comorbid PD/PDD and negative for all 19 iNPHa.

CONCLUSION

These results highlight that synucleinopathies coexist with iNPH. These can be differentiated by performing DaTscan and RT-QuIC, which can affect its clinical features.

Cumulative Damage: Cell Death in Posthemorrhagic Hydrocephalus of Prematurity

Globally, approximately 11% of all infants are born preterm, prior to 37 weeks’ gestation. In these high-risk neonates, encephalopathy of prematurity (EoP) is a major cause of both morbidity and mortality, especially for neonates who are born very preterm (<32 weeks gestation). EoP encompasses numerous types of preterm birth-related brain abnormalities and injuries, and can culminate in a diverse array of neurodevelopmental impairments. Of note, posthemorrhagic hydrocephalus of prematurity (PHHP) can be conceptualized as a severe manifestation of EoP. PHHP impacts the immature neonatal brain at a crucial timepoint during neurodevelopment, and can result in permanent, detrimental consequences to not only cerebrospinal fluid (CSF) dynamics, but also to white and gray matter development. In this review, the relevant literature related to the diverse mechanisms of cell death in the setting of PHHP will be thoroughly discussed. Loss of the epithelial cells of the choroid plexus, ependymal cells and their motile cilia, and cellular structures within the glymphatic system are of particular interest. Greater insights into the injuries, initiating targets, and downstream signaling pathways involved in excess cell death shed light on promising areas for therapeutic intervention. This will bolster current efforts to prevent, mitigate, and reverse the consequential brain remodeling that occurs as a result of hydrocephalus and other components of EoP.

The regulatory roles of motile cilia in CSF circulation and hydrocephalus

Background

Cerebrospinal fluid (CSF) is an ultra-filtrated colorless brain fluid that circulates within brain spaces like the ventricular cavities, subarachnoid space, and the spine. Its continuous flow serves many primary functions, including nourishment, brain protection, and waste removal.

Main body

The abnormal accumulation of CSF in brain cavities triggers severe hydrocephalus. Accumulating evidence had indicated that synchronized beats of motile cilia (cilia from multiciliated cells or the ependymal lining in brain ventricles) provide forceful pressure to generate and restrain CSF flow and maintain overall CSF circulation within brain spaces. In humans, the disorders caused by defective primary and/or motile cilia are generally referred to as ciliopathies. The key role of CSF circulation in brain development and its functioning has not been fully elucidated.

Conclusions

In this review, we briefly discuss the underlying role of motile cilia in CSF circulation and hydrocephalus. We have reviewed cilia and ciliated cells in the brain and the existing evidence for the regulatory role of functional cilia in CSF circulation in the brain. We further discuss the findings obtained for defective cilia and their potential involvement in hydrocephalus. Furthermore, this review will reinforce the idea of motile cilia as master regulators of CSF movements, brain development, and neuronal diseases.

Is ventriculomegaly and hindbrain herniation seen before and after prenatal neural tube defect repair associated with a worse functional level than anatomical level at birth?

OBJECTIVE

To determine if the evaluation of the fetal ventricular system and hindbrain herniation (HBH) is associated with motor outcome at birth in prenatally repaired open neural tube defect (NTD).

METHODS

Retrospective cohort study of 47 patients with NTD who underwent prenatal repair (17 fetoscopic; 30 open-hysterotomy). At referral and 6 weeks postoperatively, the degree of HBH, ventricular atrial widths and ventricular volume were evaluated by MRI. Head circumference and ventricular atrial widths were measured on ultrasound at referral and during the last ultrasound before delivery. Anatomic level of the lesion (LL) was determined based on the upper bony spinal defect detected by ultrasound. We considered the functional level as worse than anatomical level at birth when the motor level was equal or worse than the anatomical LL.

RESULTS

26% (12/47) of the cases showed worse functional level than anatomical level at birth. Having a HBH below C1 at the time of referral was associated with a worse functional level than anatomical level at birth (OR = 9.7, CI95 [2.2-42.8], p < 0.01). None of the other brain parameters showed a significant association with motor outcomes at birth.

CONCLUSIONS

HBH below C1 before surgery was associated with a worse functional level than anatomical level at birth.

Risk Factors for Hydrocephalus in Neonatal Purulent Meningitis: A Single-Center Retrospective Analysis

OBJECTIVE

Hydrocephalus is a potentially lethal complication of neonatal purulent meningitis. Early detection of hydrocephalus helps to determine optimal treatment, improve prognosis, and reduce financial burden. We aimed to analyze the risk factors for hydrocephalus in neonates with purulent meningitis and discuss the characteristics of the disease.

METHODS

The records of neonatal purulent meningitis admitted to the Children Hospital of Fudan University from January 2013 to September 2019 were retrospectively included in the study cohort. The data of clinical, laboratory, and cranial magnetic resonance images (MRIs) were collected and analyzed (except discharge data) by univariate analysis, and P values <.05 were further analyzed by multivariate logistic regression.

RESULTS

A total of 197 children who met the inclusion criteria were enrolled in the study cohort. Overall, 39.6% (78/197) of the patients had positive pathogen cultures, and 60.4% (119/197) of patients had clinical diagnosis of meningitis with negative pathogen cultures. Among 197 children, 67 of them experienced hydrocephalus, and the factors that were significantly associated with hydrocephalus in multivariate analysis were female sex, cerebrospinal fluid glucose <2 mmol/L, periventricular leukomalacia, punctate white matter lesions, and pyogenic intraventricular empyema. Children with hydrocephalus had a lower cure rate of meningitis (31.3% vs 75.4%), and poor discharge outcomes. In addition, they had longer length of hospital stay and higher hospital cost.

CONCLUSIONS

Female sex, cerebrospinal fluid glucose <2 mmol/L, periventricular leukomalacia, punctate white matter lesions, and pyogenic intraventricular empyema were identified as risk factors for hydrocephalus in neonatal purulent meningitis. Children with hydrocephalus had poor discharge outcomes and increased financial burden on their families.

Incidental Massive Hydrocephalus Associated With an Unruptured Choroid Plexus Arteriovenous Malformation and Complete Agenesis of the Corpus Callosum Found in an Adult at Autopsy

Undiagnosed significant hydrocephalus is an uncommon finding at forensic autopsy as many cases present in life with complex neurological symptoms. We present a case of a 46-year-old man with no neurological deficits or history of head trauma that was incidentally found to have a massive hydrocephalus at autopsy. This was found to be associated with an unruptured arteriovenous malformation completely confined to the choroid plexus as well as complete agenesis of the corpus callosum. The arteriovenous malformation was found to form a calcified obstruction at the foramen of Monro analogous to a mass lesion, such as a colloid cyst of the third ventricle. The association of this malformation and agenesis of the corpus callosum has never been described. Histologic examination of the brain confirmed significant loss of white matter tracts and thinning of the cortical ribbon due to pressure atrophy of the ependymal lining without significant gliosis, cortical dysplasia, or evidence of other developmental malformations. Autopsy is a vital tool in the evaluation of such rare cases, enhances epidemiologic data, and increases the understanding of these pathophysiological associations.

Deletions in CWH43 cause idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder that occurs in about 1% of individuals over age 60 and is characterized by enlarged cerebral ventricles, gait difficulty, incontinence, and cognitive decline. The cause and pathophysiology of iNPH are largely unknown. We performed whole exome sequencing of DNA obtained from 53 unrelated iNPH patients. Two recurrent heterozygous loss of function deletions in CWH43 were observed in 15% of iNPH patients and were significantly enriched 6.6‐fold and 2.7‐fold, respectively, when compared to the general population. Cwh43 modifies the lipid anchor of glycosylphosphatidylinositol‐anchored proteins. Mice heterozygous for CWH43 deletion appeared grossly normal but displayed hydrocephalus, gait and balance abnormalities, decreased numbers of ependymal cilia, and decreased localization of glycosylphosphatidylinositol‐anchored proteins to the apical surfaces of choroid plexus and ependymal cells. Our findings provide novel mechanistic insights into the origins of iNPH and demonstrate that it represents a distinct disease entity.

Ependymal ciliary motion and their role in congenital hydrocephalus

PURPOSE

Since a case of hydrocephalus in humans considered to be caused by ciliary dysfunction was first reported by Greenstone et al. in 1984, numerous papers on the correlation between ciliary function and hydrocephalus have been published.

METHODS

We reviewed the published literature on primary ciliary dyskinesia in humans causing hydrocephalus, focusing on articles specifically examining the relation between ciliary function and hydrocephalus and its treatment. In addition, the authors' experience is briefly discussed.

RESULTS

Full texts of 16 articles reporting cases of human hydrocephalus (including ventriculomegaly) due to defects in ependymal ciliary function or primary ciliary dyskinesia observed in clinical practice were extracted. In recent years, studies on animal models, especially employing knockout mice, have revealed genetic mutations that cause hydrocephalus via ciliary dysfunction. However, a few reports on the onset of hydrocephalus in human patients with primary ciliary dyskinesia have confirmed that the incidence of this condition was extremely low compared to that in animal models.

CONCLUSION

In humans, it is rare for hydrocephalus to develop solely because of abnormalities in the cilia, and it is highly likely that other factors are also involved along with ciliary dysfunction.

Abnormal cortical thickening and thinning in idiopathic normal-pressure hydrocephalus

We investigated differences in cortical thickness between idiopathic normal-pressure hydrocephalus (INPH) patients and healthy controls. We also explored whether a relationship exists between cortical thinning and gait disturbance in INPH patients. Forty-nine INPH patients and 26 healthy controls were imaged with MRI, including 3-dimensional volumetric images, for automated surface-based cortical thickness analysis across the entire brain. Compared with age- and gender-matched healthy controls, unexpectedly, INPH patients showed statistically significant cortical thickening mainly in areas located in the high convexity of the frontal, parietal, and occipital regions. Additionally, cortical thinning mainly in temporal and orbitofrontal regions was observed in the INPH group relative to the control group. The Gait Status Scale (GSS) scores were negatively correlated with cortical thickness in the medial orbital part of the superior frontal gyrus, gyrus rectus, superior temporal gyrus, temporal pole, and insula. A distinctive pattern of cortical thickness changes was found in INPH patients. We cautiously suggest that cortical thickening in INPH can result from reactive gliosis. Further, our results support the hypothesis that cortical thinning in INPH can result from neuronal degeneration. In addition, cortical thinning can play an important role in gait disturbances in INPH patients.

Fetal brain damage in congenital hydrocephalus

BACKGROUND

Congenital hydrocephalus (HCP) is a developmental brain disorder characterized by the abnormal accumulation of cerebrospinal fluid within the ventricles. It is caused by genetic and acquired factors that start during early embryogenesis with disruption of the neurogerminal areas. As might be expected, early-onset hydrocephalus alters the process of brain development leading to irreparable neurological deficit. A primary alteration of the ependyma/neural stem cells (affecting vesicle trafficking and abnormal cell junctions) leads to its loss or denudation and translocation of neural progenitor cells (NPCs) and neural stem cells (NSCs) into the cerebrospinal fluid (CSF). Under these abnormal conditions, morphological and functional processes, underlying the concept of astroglial reaction, are initiated in an attempt to recover homeostasis in the periventricular zone. This astroglial reaction includes astrocyte hypertrophy, hyperplasia, and development of a new layer with reorganized functional features that resemble the ependyma. Despite decades of research, there is a lack of information concerning the biological basis of the brain abnormalities that are associated with HCP.

DISCUSSION

The present review of current literature discusses the neuropathological changes during gestation following the onset of congenital hydrocephalus and the unanswered questions into the pathophysiology of the disease. A better understanding of those missing points might help create novel therapeutic strategies that can reverse or even prevent the ultimate neurological impairment that affects this population and improve long-term clinical outcome.

Fetal therapy for congenital hydrocephalus-where we came from and where we are going

Despite unfavorable outcomes during the early experience with in utero intervention for congenital hydrocephalus, improvements in prenatal diagnosis, patient selection, and fetal surgery techniques have led to a renewed interest in fetal intervention for congenital hydrocephalus. Research studies and clinical evidence shows that postnatal cerebrospinal fluid diversion to release intraventricular pressure and cerebral mantle compression usually arrives late to avoid irreversible brain damage. Make sense to decompress those lateral ventricles as soon as possible during the intrauterine life when hydrocephalus is antenatally detected. We present a historical review of research in animal models as well as clinical experience in the last decades, traveling until the last years when some research fetal therapy groups have made significant progress in recapitulating the prenatal intervention for fetuses with congenital obstructive hydrocephalus.

Physiology of cerebrospinal fluid circulation

PURPOSE OF REVIEW

This article describes the physiology of cerebrospinal fluid (CSF). We review current evidence and new concepts relating to CSF physiology with respect to CSF secretion, circulation and resorption and we highlight key pathophysiological associations including the relationship between CSF and intracranial pressure.

RECENT FINDINGS

CSF secretion occurs primarily via the choroid plexus. Various transport mechanisms facilitate CSF secretion but the role Aquaporins play in this process is a recent discovery and an area of ongoing research. CSF circulation is a dynamic process but the importance of the perivascular 'Glymphatic system' and extraarachnoidal pathways of resorption are relatively new concepts.

SUMMARY

CSF physiology is dependent on various interacting factors and is critical for normal brain development and function.

Kaolin-induced hydrocephalus causes acetylcholinesterase activity dysfunction following hypothalamic damage in infant rats

In hydrocephalus, the progressive accumulation of cerebrospinal fluid (CSF) causes dilatation of the lateral ventricles affecting the third ventricle and diencephalic structures such as the hypothalamus. These structures play a key role in the regulation of several neurovegetative functions by the production of the hormones. Since endocrine disturbances are commonly observed in hydrocephalic children, we investigated the impact of progressive ventricular dilation on the hypothalamus of infant rats submitted to kaolin-induced hydrocephalus. Seven-day-old infant rats were submitted to hydrocephalus induction by kaolin 20% injection method. After 14 days, the animals were decapitated and brain was collected to analyze mitochondrial function, neuronal activity by acetylcholinesterase (AChE) enzyme, oxidative damage, glial activation, and, neurotransmission-related proteins and anti-apoptotic processes in the hypothalamus. The hydrocephalic animals showed reduction in respiratory rates in the States of phosphorylation (P < 0.01) and non-phosphorylation (P < 0.05); increase in AChE activity in both the cytosol (P < 0.05) and the membrane (P < 0.01); decrease in synaptophysin (P < 0.05) and Bcl-2 (P < 0.05) contents and; increase in protein carbonyl (P < 0.01), GFAP (P < 0.01) and Iba-1 (P < 0.05) levels. The results demonstrate that ventricular dilation causes hypothalamic damage characterized by cholinergic dysfunction and suggests further investigation of the synthesis and secretion of hormones to generate new approaches and to assist in the treatment of hydrocephalic patients with hormonal alterations.

Predictors of neuropsychological late effects and white matter correlates in children treated for a brain tumor without radiation therapy

BACKGROUND

Little is known about cognition and predictors of neuropsychological outcomes in pediatric low-grade glioma (PLGG) survivors treated without radiation therapy. This research expands upon our previous work by further identifying the cognitive profile of PLGG patients treated without radiation therapy, investigating the specific medical and demographic variables that predict functioning, and examining white matter structure and its relationship to neuropsychological performance.

PROCEDURE

Nineteen PLGG patients (11-19 years) were administered the Wechsler Intelligence Scale for Children/Wechsler Adult Intelligence Scale, and subtests from the Woodcock-Johnson Tests of Cognition (visual matching, rapid picture naming, and pair cancellation) and Cambridge Neuropsychological Test Automated Battery (pattern recognition memory, delayed matching to sample, intra-extra dimensional set shift, motor screening task, rapid visual information processing, and spatial span).

RESULTS

The sample had normative weaknesses in verbal working memory, brief attention/vigilance, psychomotor speeded output, visual perception and matching, overall cognition, working memory, and processing speed. Increased surgeries or subtotal resections, hydrocephalus, shunting procedures, chemotherapy, NF1, and supratentorial location were predictive of cognitive deficits. Broad white matter involvement of the frontal, temporal, parietal, and occipital lobes as well as the cerebellum, as inferred from diffusion tensor imaging indices of decreased fiber orientation and increased water diffusion, was related to many cognitive difficulties.

CONCLUSIONS

This study comprehensively examines cognitive functioning in PLGG patients treated without radiation therapy, predictors of cognition, and its relation to white matter structure. Our findings indicate that medical and demographic variables other than radiation therapy can lead to cognitive late effects with diffuse white matter involvement.

A Rat Model of Neurocysticercosis-Induced Hydrocephalus: Chronic Progressive Hydrocephalus with Mild Clinical Impairment

BACKGROUND

Hydrocephalus is the most common complication of extraparenchymal neurocysticercosis, combining obstructive and inflammatory mechanisms that impair cerebrospinal fluid circulation.

METHODS

We studied the long-term progression of neurocysticercosis-induced hydrocephalus in a rat model. We generated an experimental rat model of neurocysticercosis-induced hydrocephalus by cisternal inoculation of cysts or antigens of Taenia crassiceps and compared it with the classic model of kaolin-induced hydrocephalus. We used 52 animals divided into 4 groups: 1) control, 2) neurocysticercosis-induced hydrocephalus by cysts or 3) by antigens, and 4) kaolin-induced hydrocephalus. We studied behavioral, radiologic, and morphologic alterations at 1 and 6 months after inoculation by open field test, magnetic resonance imaging, and immunohistochemical localization of aquaporin-4 (AQP-4).

RESULTS

Behavioral changes were observed later in neurocysticercosis-induced than in kaolin-induced hydrocephalic rats (P = 0.023). The ventricular volume of hydrocephalus induced by experimental neurocysticercosis progressively evolved, with the magnetic resonance imaging changes being similar to those observed in humans. Periventricular inflammatory and astrocytic reactions were also observed. AQP-4 expression was higher in the sixth than in the first month after inoculation (P = 0.016) and also occurred in animals that received antigen inoculation but did not develop hydrocephalus, suggesting that AQP-4 may constitute an alternative route of cerebrospinal fluid absorption under inflammatory conditions.

CONCLUSIONS

Our neurocysticercosis-induced hydrocephalus model allows for the long-term maintenance of hydrocephalic animals, involving mild clinical performance impairments, including body weight and behavioral changes.

Fetal aqueductal stenosis: Prenatal diagnosis and intervention

Fetal severe central nervous system ventriculomegaly is associated with poor neurologic outcomes, usually driven by a primary malformation, deformation, or disruption of brain parenchyma. In utero shunting of excess cerebrospinal fluid (CSF) in hopes of improving neurologic outcomes was attempted in the 1980s but was abandoned due to perceived lack of effect, likely due to technological limitations of the time that precluded proper patient selection. Little progress on the antenatal management of severe ventriculomegaly has been made in the intervening decades. A multidisciplinary, evidence-based reassessment of ventriculoamniotic shunting for isolated fetal aqueductal stenosis (FAS), a unique form of severe ventriculomegaly (supratentorial intracranial hypertension), is currently underway. An accurate diagnosis of FAS must precede in utero intervention. Magnetic resonance imaging (MRI) will be an excellent adjunct to high-resolution prenatal ultrasound and next-generation genetic testing to correctly diagnose FAS in a timely fashion while excluding other intracranial and extracranial anomalies. This manuscript will briefly discuss the history, current management, and future directions of the prenatal diagnosis and potential intervention for FAS.

Lateral Ventricle Enlargement and Cortical Thinning in Idiopathic Normal-pressure Hydrocephalus Patients

We utilized three-dimensional, surface-based, morphometric analysis to investigate ventricle shape between 2 groups: (1) idiopathic normal-pressure hydrocephalus (INPH) patients who had a positive response to the cerebrospinal fluid tap test (CSFTT) and (2) healthy controls. The aims were (1) to evaluate the location of INPH-related structural abnormalities of the lateral ventricles and (2) to investigate relationships between lateral ventricular enlargement and cortical thinning in INPH patients. Thirty-three INPH patients and 23 healthy controls were included in this study. We used sparse canonical correlation analysis to show correlated regions of ventricular surface expansion and cortical thinning. Significant surface expansion in the INPH group was observed mainly in clusters bilaterally located in the superior portion of the lateral ventricles, adjacent to the high convexity of the frontal and parietal regions. INPH patients showed a significant bilateral expansion of both the temporal horns of the lateral ventricles and the medial aspects of the frontal horns of the lateral ventricles to surrounding brain regions, including the medial frontal lobe. Ventricular surface expansion was associated with cortical thinning in the bilateral orbitofrontal cortex, bilateral rostral anterior cingulate cortex, left parahippocampal cortex, left temporal pole, right insula, right inferior temporal cortex, and right fusiform gyrus. These results suggest that patients with INPH have unique patterns of ventricular surface expansion. Our findings encourage future studies to elucidate the underlying mechanism of lateral ventricular morphometric abnormalities in INPH patients.

Acupuncture at ST36 exerts neuroprotective effects via inhibition of reactive astrogliosis in infantile rats with hydrocephalus

BACKGROUND

Acupuncture has been associated with improved cerebral circulation, analgesia, neuromodulatory function and neurogenesis. In particular, acupuncture at ST36 has been widely used in several central nervous system (CNS) disorders, including neurodegenerative diseases. However, its effects on hydrocephalus have not been studied. Our aim was to evaluate the effects of acupuncture at ST36 on behaviour, motor development and reactive astrogliosis in infantile rats with hydrocephalus.

METHODS

Hydrocephalus was induced in sixteen 7-day-old pup rats by injection of 20% kaolin into the cisterna magna. One day after hydrocephalus induction, acupuncture was applied once daily (for 30 min) for a total of 21 days in eight randomly selected animals (HAc group) while the remaining eight remained untreated (H group). An additional eight healthy animals were included as controls (C group). All animals were weighed daily and, from the fifth day after hydrocephalus induction, underwent MRI to determine the ventricular ratio (VR). Rats were also exposed to modified open-field tests every 3 days until the end of the experiment. After 21 days all the animals were euthanased and their brains removed for histology and immunohistochemistry.

RESULTS

Hydrocephalic rats showed an increase in VR when compared with control rats (P<0.01). In addition, these animals exhibited delayed weight gain, which was attenuated with acupuncture treatment. Hydrocephalic animals treated with acupuncture performed better in open field tests (P<0.05), and had a reduction in reactive astrocyte cell density in the corpus callosum and external capsule, as assessed by GFAP (glial fibrillary acidic protein) immunohistochemistry (P<0.05).

CONCLUSIONS

These findings indicate that acupuncture at ST36 has a neuroprotective potential mediated, in part, by inhibition of astrogliosis.

Estimation of elevated intracranial pressure in infants with hydroce-phalus by using transcranial Doppler velocimetry with fontanel compression

For infants with acute progressive hydrocephalus, invasive drainage of cerebrospinal fluid (CSF) is performed until a ventriculo-peritoneal shunt can be inserted. Surrogate markers of intracranial pressure (ICP) may help optimise the timing of invasive procedures. To assess whether RI with/without fontanel compression helps distinguish between infants with normal (<5 cmH₂O), mild (5-11 cmH₂O), and moderate (>11 cmH₂O) ICP elevation, 74 ICP measures before/after CSF removal and 148 related Doppler measures of the middle cerebral artery were assessed. Higher RI was associated with fontanel compression, elevated ICP, and their interaction (all p < 0.001). Without compression, differences in RI were observed between normal and moderate (p < 0.001) and between mild and moderate ICP elevation (p = 0.033). With compression, differences in RI were observed for all pairwise comparisons among normal, mild, and moderate ICP elevation (all p < 0.001). Without compression, areas under the receiver-operating characteristic curve for prediction of mild and moderate ICP elevation were 0.664 (95% confidence interval (CI), 0.538-0.791; p = 0.020) and 0.727 (95% CI, 0.582-0.872; p = 0.004), respectively, which improved to 0.806 (95% CI, 0.703-0.910; p < 0.001) and 0.814 (95% CI, 0.707-0.921; p < 0.001), respectively, with compression. RI with fontanel compression provides improved discrimination of infants with absent, mild, and moderate ICP elevation.

Ventricular and Periventricular Anomalies in the Aging and Cognitively Impaired Brain

Ventriculomegaly (expansion of the brain’s fluid-filled ventricles), a condition commonly found in the aging brain, results in areas of gliosis where the ependymal cells are replaced with dense astrocytic patches. Loss of ependymal cells would compromise trans-ependymal bulk flow mechanisms required for clearance of proteins and metabolites from the brain parenchyma. However, little is known about the interplay between age-related ventricle expansion, the decline in ependymal integrity, altered periventricular fluid homeostasis, abnormal protein accumulation and cognitive impairment. In collaboration with the Baltimore Longitudinal Study of Aging (BLSA) and Alzheimer’s Disease Neuroimaging Initiative (ADNI), we analyzed longitudinal structural magnetic resonance imaging (MRI) and subject-matched fluid-attenuated inversion recovery (FLAIR) MRI and periventricular biospecimens to map spatiotemporally the progression of ventricle expansion and associated periventricular edema and loss of transependymal exchange functions in healthy aging individuals and those with varying degrees of cognitive impairment. We found that the trajectory of ventricle expansion and periventricular edema progression correlated with degree of cognitive impairment in both speed and severity, and confirmed that areas of expansion showed ventricle surface gliosis accompanied by edema and periventricular accumulation of protein aggregates, suggesting impaired clearance mechanisms in these regions. These findings reveal pathophysiological outcomes associated with normal brain aging and cognitive impairment, and indicate that a multifactorial analysis is best suited to predict and monitor cognitive decline.

The MRL Model: A Valuable Tool in Studies of Autoimmunity-Brain Interactions

The link between systemic autoimmunity, brain pathology, and aberrant behavior is still a largely unexplored field of biomedical science. Accumulating evidence points to causal relationships between immune factors, neurodegeneration, and neuropsychiatric manifestations. By documenting autoimmunity-associated neuronal degeneration and cytotoxicity of the cerebrospinal fluid from disease-affected subjects, the murine MRL model had shown high validity in revealing principal pathogenic circuits. In addition, unlike any other autoimmune strain, MRL mice produce antibodies commonly found in patients suffering from lupus and other autoimmune disorders. This review highlights importance of the MRL model as a useful preparation in understanding the links between immune system and brain function.

Neuroimaging in Dementia

Although the diagnosis of dementia still is primarily based on clinical criteria, neuroimaging is playing an increasingly important role. This is in large part due to advances in techniques that can assist with discriminating between different syndromes. Magnetic resonance imaging remains at the core of differential diagnosis, with specific patterns of cortical and subcortical changes having diagnostic significance. Recent developments in molecular PET imaging techniques have opened the door for not only antemortem but early, even preclinical, diagnosis of underlying pathology. This is vital, as treatment trials are underway for pharmacological agents with specific molecular targets, and numerous failed trials suggest that earlier treatment is needed. This article provides an overview of classic neuroimaging findings as well as new and cutting-edge research techniques that assist with clinical diagnosis of a range of dementia syndromes, with an emphasis on studies using pathologically proven cases.

Dynamic Susceptibility Contrast Perfusion Magnetic Resonance Imaging Demonstrates Reduced Periventricular Cerebral Blood Flow in Dogs with Ventriculomegaly

The nature of ventriculomegaly in dogs is still a matter of debate. Signs of increased intraventricular pressure and atrophy of the cerebral white matter have been found in dogs with ventriculomegaly, which would imply increased intraventricular pressure and, therefore, a pathological condition, i.e., to some extent. Reduced periventricular blood flow was found in people with high elevated intraventricular pressure. The aim of this study was to compare periventricular brain perfusion in dogs with and without ventriculomegaly using perfusion weighted-magnetic-resonance-imaging to clarify as to whether ventriculomegaly might be associated with an increase in intraventricular pressure. Perfusion was measured in 32 Cavalier King Charles spaniels (CKCS) with ventriculomegaly, 10 CKCSs were examined as a control group. Cerebral blood flow (CBF) was measured using free-hand regions of interest (ROI) in five brain regions: periventricular white matter, caudate nucleus, parietal cortex, hippocampus, and thalamus. CBF was significantly lower in the periventricular white matter of the dogs with ventriculomegaly (p = 0.0029) but not in the other ROIs. Reduction of periventricular CBF might imply increase of intraventricular pressure in ventriculomegaly.

Predictors of permanent disability among adults with spinal dysraphism

OBJECTIVE Predictors of permanent disability among individuals with spinal dysraphism are not well established. In this study, the authors examined potential risk factors for self-reported permanent disability among adults with spinal dysraphism. METHODS A total of 188 consecutive individuals undergoing follow-up in an adult spinal dysraphism clinic completed a standardized National Spina Bifida Patient Registry survey. Chi-square tests and logistic regression were used to assess bivariate relationships, while multivariate logistic regression was used to identify factors independently associated with self-identification as "permanently disabled." RESULTS A total of 106 (56.4%) adults with spina bifida identified themselves as permanently disabled. On multivariate analysis, relative to completion of primary and/or secondary school, completion of technical school (OR 0.01, 95% CI 0-0.40; p = 0.021), some college (OR 0.22, 95% CI 0.08-0.53; p < 0.001), college degree (OR 0.06, 95% CI 0.003-0.66; p = 0.019), and holding an advanced degree (OR 0.12, 95% CI 0.03-0.45; p = 0.002) were negatively associated with permanent disability. Relative to open myelomeningocele, diagnosis of closed spinal dysraphism was also negatively associated with permanent disability (OR 0.20, 95% CI 0.04-0.90; p = 0.036). Additionally, relative to no stool incontinence, stool incontinence occurring at least daily (OR 6.41, 95% CI 1.56-32.90; p = 0.009) or more than weekly (OR 3.43, 95% CI 1.10-11.89; p = 0.033) were both positively associated with permanent disability. There was a suggestion of a dose-response relationship with respect to the influence of educational achievement and frequency of stool incontinence on the likelihood of permanent disability. CONCLUSIONS The authors' findings suggest that level of education and degree of stool incontinence are the strongest predictors of permanent disability among adults with spinal dysraphism. These findings will be the basis of efforts to improve community engagement and to improve readiness for transition to adult care in a multidisciplinary pediatric spina bifida clinic.