Priorities for hydrocephalus research: report from a National Institutes of Health-sponsored workshop

The Construction of a Predictive Composite Index for Decision-Making of CSF Diversion Surgery in Pediatric Patients following Prenatal Myelomeningocele Repair

BACKGROUND AND PURPOSE

There is a wide range of clinical and radiographic factors affecting individual surgeons' ultimate decision for CSF diversion for pediatric patients following prenatal myelomeningocele repair. Our aim was to construct a composite index (CSF diversion surgery index) that integrates conventional clinical measures and neuroimaging biomarkers to predict CSF diversion surgery in these pediatric patients.

MATERIALS AND METHODS

This was a secondary retrospective analysis of data from 33 patients with prenatal myelomeningocele repair (including 14 who ultimately required CSF diversion surgery). Potential independent variables, including the Management of Myelomeningocele Study Index (a dichotomized variable based on the shunt-placement criteria from the Management of Myelomeningocele Study), postnatal DTI measures (fractional anisotropy and mean diffusivity in the genu of the corpus callosum and the posterior limb of internal capsule), fronto-occipital horn ratio at the time of DTI, gestational ages, and sex, were evaluated using stepwise logistic regression analysis to identify the most important predictors.

RESULTS

The CSF diversion surgery index model showed that the Management of Myelomeningocele Study Index and fractional anisotropy in the genu of the corpus callosum were significant predictors (P < .05) of CSF diversion surgery. The predictive value of the CSF diversion surgery index was also affected by fractional anisotropy in the posterior limb of the internal capsule and sex with marginal effect (.05<P < .10), but not by the fronto-occipital horn ratio (P > .10). The overall CSF diversion surgery index model fit the data well with statistical significance (eg, likelihood ratio: P < .001), with the performance (sensitivity = 78.6%; specificity = 86.5%, overall accuracy = 84.8%) superior to all individual indices in sensitivity and overall accuracy, and most of the individual indices in specificity.

CONCLUSIONS

The CSF diversion surgery index model outperformed all single predictor models and, with additional validation, may potentially be developed and incorporated into a sensitive and robust clinical tool to assist clinicians in hydrocephalus management.

Programmable Shunt Valves for Pediatric Hydrocephalus: 22-Year Experience from a Singapore Children's Hospital

(1) Background: pediatric hydrocephalus is a challenging condition. Programmable shunt valves (PSV) have been increasingly used. This study is undertaken to firstly, to objectively evaluate the efficacy of PSV as a treatment modality for pediatric hydrocephalus; and next, review its associated patient outcomes at our institution. Secondary objectives include the assessment of our indications for PSV, and corroboration of our results with published literature. (2) Methods: this is an ethics-approved, retrospective study. Variables of interest include age, gender, hydrocephalus etiology, shunt failure rates and incidence of adjustments made per PSV. Data including shunt failure, implant survival, and utility comparisons between PSV types are subjected to statistical analyses. (3) Results: in this case, 51 patients with PSV are identified for this study, with 32 index and 19 revision shunts. There are 3 cases of shunt failure (6%). The mean number of adjustments per PSV is 1.82 times and the mean number of adjustments made per PSV is significantly lower for MEDTRONIC™ Strata PSVs compared with others (p = 0.031). Next, PSV patients that are adjusted more frequently include cases of shunt revisions, PSVs inserted due to CSF over-drainage and tumor-related hydrocephalus. (4) Conclusion: we describe our institutional experience of PSV use in pediatric hydrocephalus and its advantages in a subset of patients whose opening pressures are uncertain and evolving.

A novel model of acquired hydrocephalus for evaluation of neurosurgical treatments

Background

Many animal models have been used to study the pathophysiology of hydrocephalus; most of these have been rodent models whose lissencephalic cerebral cortex may not respond to ventriculomegaly in the same way as gyrencephalic species and whose size is not amenable to evaluation of clinically relevant neurosurgical treatments. Fewer models of hydrocephalus in gyrencephalic species have been used; thus, we have expanded upon a porcine model of hydrocephalus in juvenile pigs and used it to explore surgical treatment methods.

Methods

Acquired hydrocephalus was induced in 33–41-day old pigs by percutaneous intracisternal injections of kaolin (n = 17). Controls consisted of sham saline-injected (n = 6) and intact (n = 4) animals. Magnetic resonance imaging (MRI) was employed to evaluate ventriculomegaly at 11–42 days post-kaolin and to plan the surgical implantation of ventriculoperitoneal shunts at 14–38-days post-kaolin. Behavioral and neurological status were assessed.

Results

Bilateral ventriculomegaly occurred post-induction in all regions of the cerebral ventricles, with prominent CSF flow voids in the third ventricle, foramina of Monro, and cerebral aqueduct. Kaolin deposits formed a solid cast in the basal cisterns but the cisterna magna was patent. In 17 untreated hydrocephalic animals. Mean total ventricular volume was 8898 ± 5917 SD mm³ at 11–43 days of age, which was significantly larger than the baseline values of 2251 ± 194 SD mm³ for 6 sham controls aged 45–55 days, (p < 0.001). Past the post-induction recovery period, untreated pigs were asymptomatic despite exhibiting mild-moderate ventriculomegaly. Three out of 4 shunted animals showed a reduction in ventricular volume after 20–30 days of treatment, however some developed ataxia and lethargy, from putative shunt malfunction.

Conclusions

Kaolin induction of acquired hydrocephalus in juvenile pigs produced an in vivo model that is highly translational, allowing systematic studies of the pathophysiology and clinical treatment of hydrocephalus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00281-0.

Molecular Characterization of Microbiota in Cerebrospinal Fluid From Patients With CSF Shunt Infections Using Whole Genome Amplification Followed by Shotgun Sequencing

Understanding the etiology of cerebrospinal fluid (CSF) shunt infections and reinfections requires detailed characterization of associated microorganisms. Traditionally, identification of bacteria present in the CSF has relied on culture methods, but recent studies have used high throughput sequencing of 16S rRNA genes. Here we evaluated the method of shotgun DNA sequencing for its potential to provide additional genomic information. CSF samples were collected from 3 patients near the beginning and end of each of 2 infection episodes. Extracted total DNA was sequenced by: (1) whole genome amplification followed by shotgun sequencing (WGA) and (2) high-throughput sequencing of the 16S rRNA V4 region (16S). Taxonomic assignments of sequences from WGA and 16S were compared with one another and with conventional microbiological cultures. While classification of bacteria was consistent among the 3 approaches, WGA provided additional insights into sample microbiological composition, such as showing relative abundances of microbial versus human DNA, identifying samples of questionable quality, and detecting significant viral load in some samples. One sample yielded sufficient non-human reads to allow assembly of a high-quality Staphylococcus epidermidis genome, denoted CLIMB1, which we characterized in terms of its MLST profile, gene complement (including putative antimicrobial resistance genes), and similarity to other annotated S. epidermidis genomes. Our results demonstrate that WGA directly applied to CSF is a valuable tool for the identification and genomic characterization of dominant microorganisms in CSF shunt infections, which can facilitate molecular approaches for the development of better diagnostic and treatment methods.

Characterization of cerebrospinal fluid (CSF) microbiota from patients with CSF shunt infection and reinfection using high throughput sequencing of 16S ribosomal RNAgenes

BACKGROUND

Nearly 20% of patients with cerebrospinal fluid (CSF) shunt infection develop reinfection. It is unclear whether reinfections are caused by an organism previously present or are independent infection events.

OBJECTIVE

We used bacterial culture and high throughput sequencing (HTS) of 16S ribosomal RNA (rRNA) genes to identify bacteria present in serial CSF samples obtained from children who failed CSF shunt infection treatment. We hypothesized that organisms that persist in CSF despite treatment would be detected upon reinfection.

DESIGN/METHODS

Serial CSF samples were obtained from 6 patients, 5 with 2 infections and 1 with 3 infections; the study was limited to those for which CSF samples were available from the end of infection and beginning of reinfection. Amplicons of the 16S rRNA gene V4 region were sequenced. Taxonomic assignments of V4 sequences were compared with bacterial species identified in culture.

RESULTS

Seven infection dyads averaging 13.5 samples per infection were analyzed. A median of 8 taxa [interquartile range (IQR) 5-10] were observed in the first samples from reinfection using HTS. Conventional culture correlated with high abundance of an organism by HTS in all but 1 infection. In 6 of 7 infection dyads, organisms identified by culture at reinfection were detected by HTS of culture-negative samples at the end of the previous infection. The median Chao-Jaccard abundance-based similarity index for matched infection pairs at end of infection and beginning of reinfection was 0.57 (IQR 0.07-0.87) compared to that for unmatched pairs of 0.40 (IQR 0.10-0.60) [p = 0.46].

CONCLUSION(S)

HTS results were generally consistent with culture-based methods in CSF shunt infection and reinfection, and may detect organisms missed by culture at the end of infection treatment but detected by culture at reinfection. However, the CSF microbiota did not correlate more closely within patients at the end of infection and beginning of reinfection than between any two unrelated infections. We cannot reject the hypothesis that sequential infections were independent.

The Current State of Clinical Trials Studying Hydrocephalus: An Analysis of ClinicalTrials.gov

Introduction

Hydrocephalus is a significant public health concern estimated to affect 380,000 new individuals annually. In addition, it exhibits an increasingly high financial burden for the healthcare industry. Clinical trials are the gold standard for evaluating preventative and therapeutic strategies to bring potential treatments to the forefront of clinical practice.

Methods

A study of the ClinicalTrials.gov was conducted in April 2019 to examine all current and previously reported clinical trials studying hydrocephalus. Studies were reviewed to extrapolate information to characterize the current state of research being conducted for hydrocephalus.

Results

In total, 80 clinical trials met inclusion criteria and were analyzed: 48.8% were observation and 51.2% were interventional. Of those, 55% have been completed while 30.0% are still recruiting, and 15.0% are not yet recruiting. The United States has the most clinical trials (42.0%) and a plurality of trials has a sample size of 0-50 participants. The majority of studies included only adults (53.8%). Of those studies, 54.0% were cohort and the majority were prospective (74.0%). Of the different types of hydrocephalus, normal pressure hydrocephalus and pediatric hydrocephalus have generated the most interest for research comprising a majority of the clinical trial registry. While 44 of the trials are complete, only 20 have published results in peer-reviewed literature highlighting the need for improvement in publishing study results even if the results of the trials are null.

Conclusion

Most clinical trials to date have pertained to the treatment of normal pressure hydrocephalus and pediatric hydrocephalus. While great advancements have been made for the treatment of hydrocephalus, there remains much room for improvements in therapeutic interventional modalities as well as ensuring the reporting of all undertaken clinical trials.

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.

Characterization of a multicenter pediatric-hydrocephalus shunt biobank

BACKGROUND

Pediatric hydrocephalus is a devastating and costly disease. The mainstay of treatment is still surgical shunting of cerebrospinal fluid (CSF). These shunts fail at a high rate and impose a significant burden on patients, their families and society. The relationship between clinical decision making and shunt failure is poorly understood and multifaceted, but catheter occlusion remains the most frequent cause of shunt complications. In order to investigate factors that affect shunt failure, we have established the Wayne State University (WSU) shunt biobank.

METHODS

To date, four hospital centers have contributed various components of failed shunts and CSF from patients diagnosed with hydrocephalus before adulthood. The hardware samples are transported in paraformaldehyde and transferred to phosphate-buffered saline with sodium azide upon deposit into the biobank. Once in the bank, they are then available for study. Informed consent is obtained by the local center before corresponding clinical data are entered into a REDCap database. Data such as hydrocephalus etiology and details of shunt revision history. All data are entered under a coded identifier.

RESULTS

293 shunt samples were collected from 228 pediatric patients starting from May 2015 to September 2019. We saw a significant difference in the number of revisions per patient between centers (Kruskal-Wallis H test, p value < 0.001). The leading etiology at all centers was post-hemorrhagic hydrocephalus, a fisher's exact test showed there to be statistically significant differences in etiology between center (p = 0.01). Regression showed age (p < 0.01), race (p = 0.038) and hospital-center (p < 0.001) to explain significant variance in the number of revisions. Our model accounted for 31.9% of the variance in revisions. Generalized linear modeling showed hydrocephalus etiology (p < 0.001), age (p < 0.001), weight and physician (p < 0.001) to impact the number of ventricular obstructions.

CONCLUSION

The retrospective analysis identified that differences exist between currently enrolled centers, although further work is needed before clinically actionable recommendations can be made. Moreover, the variables collected from this chart review explain a meaningful amount of variance in the number of revision surgeries. Future work will expand on the contribution of different site-specific and patient-specific factors to identify potential cause and effect relationships.

Neural stem cell therapy of foetal onset hydrocephalus using the HTx rat as experimental model

Foetal onset hydrocephalus is a disease starting early in embryonic life; in many cases it results from a cell junction pathology of neural stem (NSC) and neural progenitor (NPC) cells forming the ventricular zone (VZ) and sub-ventricular zone (SVZ) of the developing brain. This pathology results in disassembling of VZ and loss of NSC/NPC, a phenomenon known as VZ disruption. At the cerebral aqueduct, VZ disruption triggers hydrocephalus while in the telencephalon, it results in abnormal neurogenesis. This may explain why derivative surgery does not cure hydrocephalus. NSC grafting appears as a therapeutic opportunity. The present investigation was designed to find out whether this is a likely possibility. HTx rats develop hereditary hydrocephalus; 30-40% of newborns are hydrocephalic (hyHTx) while their littermates are not (nHTx). NSC/NPC from the VZ/SVZ of nHTx rats were cultured into neurospheres that were then grafted into a lateral ventricle of 1-, 2- or 7-day-old hyHTx. Once in the cerebrospinal fluid, neurospheres disassembled and the freed NSC homed at the areas of VZ disruption. A population of homed cells generated new multiciliated ependyma at the sites where the ependyma was missing due to the inherited pathology. Another population of NSC homed at the disrupted VZ differentiated into βIII-tubulin+ spherical cells likely corresponding to neuroblasts that progressed into the parenchyma. The final fate of these cells could not be established due to the protocol used to label the grafted cells. The functional outcomes of NSC grafting in hydrocephalus remain open. The present study establishes an experimental paradigm of NSC/NPC therapy of foetal onset hydrocephalus, at the etiologic level that needs to be further explored with more analytical methodologies.

Current Update on Treatment Strategies for Idiopathic Normal Pressure Hydrocephalus

PURPOSE OF REVIEW

Idiopathic normal pressure hydrocephalus (iNPH) is a surgically treatable neurological disorder of the elderly population that is characterized by abnormal ventricular enlargement due to cerebrospinal fluid (CSF) accumulation and gait disturbance, cognitive impairment, or urinary incontinence. The objective of this review is to present the current diagnostic and treatment approaches for iNPH and to discuss some of the postoperative modalities that complement positive surgical outcomes.

RECENT FINDINGS

Although historically reported patient outcomes following iNPH surgery were dismal and highly variable, recent advances in terms of better understanding of the iNPH disease process, better standardization of iNPH diagnostic and treatment processes arising from the adoption of clinical guidelines for diagnosis, treatment and in research methodologies, and availability of long-term follow-up data, have helped reduce the variations to a much improved 73 to 96% reported good outcomes. With careful evaluation, good patient selection, and advanced surgical techniques, iNPH can be surgically treated to return patients close to their pre-iNPH functional status. Institution of an interdisciplinary effort to rehabilitate patients following surgery may help augment their recovery.

Reinfection after treatment of first cerebrospinal fluid shunt infection: a prospective observational cohort study

OBJECTIVE CSF shunt infection requires both surgical and antibiotic treatment. Surgical treatment includes either total shunt removal with external ventricular drain (EVD) placement followed by new shunt insertion, or distal shunt externalization followed by new shunt insertion once the CSF is sterile. Antibiotic treatment includes the administration of intravenous antibiotics. The Hydrocephalus Clinical Research Network (HCRN) registry provides a unique opportunity to understand reinfection following treatment for CSF shunt infection. This study examines the association of surgical and antibiotic decisions in the treatment of first CSF shunt infection with reinfection. METHODS A prospective cohort study of children undergoing treatment for first CSF infection at 7 HCRN hospitals from April 2008 to December 2012 was performed. The HCRN consensus definition was used to define CSF shunt infection and reinfection. The key surgical predictor variable was surgical approach to treatment for CSF shunt infection, and the key antibiotic treatment predictor variable was intravenous antibiotic selection and duration. Cox proportional hazards models were constructed to address the time-varying nature of the characteristics associated with shunt surgeries. RESULTS Of 233 children in the HCRN registry with an initial CSF shunt infection during the study period, 38 patients (16%) developed reinfection over a median time of 44 days (interquartile range [IQR] 19-437). The majority of initial CSF shunt infections were treated with total shunt removal and EVD placement (175 patients; 75%). The median time between infection surgeries was 15 days (IQR 10-22). For the subset of 172 infections diagnosed by CSF culture, the mean ± SD duration of antibiotic treatment was 18.7 ± 12.8 days. In all Cox proportional hazards models, neither surgical approach to infection treatment nor overall intravenous antibiotic duration was independently associated with reinfection. The only treatment decision independently associated with decreased infection risk was the use of rifampin. While this finding did not achieve statistical significance, in all 5 Cox proportional hazards models both surgical approach (other than total shunt removal at initial CSF shunt infection) and nonventriculoperitoneal shunt location were consistently associated with a higher hazard of reinfection, while the use of ultrasound was consistently associated with a lower hazard of reinfection. CONCLUSIONS Neither surgical approach to treatment nor antibiotic duration was associated with reinfection risk. While these findings did not achieve statistical significance, surgical approach other than total removal at initial CSF shunt infection was consistently associated with a higher hazard of reinfection in this study and suggests the feasibility of controlling and standardizing the surgical approach (shunt removal with EVD placement). Considerably more variation and equipoise exists in the duration and selection of intravenous antibiotic treatment. Further consideration should be given to the use of rifampin in the treatment of CSF shunt infection. High-quality studies of the optimal duration of antibiotic treatment are critical to the creation of evidence-based guidelines for CSF shunt infection treatment.

Opportunities in posthemorrhagic hydrocephalus research: outcomes of the Hydrocephalus Association Posthemorrhagic Hydrocephalus Workshop

The Hydrocephalus Association Posthemorrhagic Hydrocephalus Workshop was held on July 25 and 26, 2016 at the National Institutes of Health. The workshop brought together a diverse group of researchers including pediatric neurosurgeons, neurologists, and neuropsychologists with scientists in the fields of brain injury and development, cerebrospinal and interstitial fluid dynamics, and the blood-brain and blood-CSF barriers. The goals of the workshop were to identify areas of opportunity in posthemorrhagic hydrocephalus research and encourage scientific collaboration across a diverse set of fields. This report details the major themes discussed during the workshop and research opportunities identified for posthemorrhagic hydrocephalus. The primary areas include (1) preventing intraventricular hemorrhage, (2) stopping primary and secondary brain damage, (3) preventing hydrocephalus, (4) repairing brain damage, and (5) improving neurodevelopment outcomes in posthemorrhagic hydrocephalus.

Variability in Management of First Cerebrospinal Fluid Shunt Infection: A Prospective Multi-Institutional Observational Cohort Study

OBJECTIVES

To describe the variation in approaches to surgical and antibiotic treatment for first cerebrospinal fluid (CSF) shunt infection and adherence to Infectious Diseases Society of America (IDSA) guidelines.

STUDY DESIGN

We conducted a prospective cohort study of children undergoing treatment for first CSF infection at 7 Hydrocephalus Clinical Research Network hospitals from April 2008 through December 2012. Univariate analyses were performed to describe the study population.

RESULTS

A total of 151 children underwent treatment for first CSF shunt-related infection. Most children had undergone initial CSF shunt placement before the age of 6 months (n =  98, 65%). Median time to infection after shunt surgery was 28 days (IQR 15-52 days). Surgical management was most often shunt removal with interim external ventricular drain placement, followed by new shunt insertion (n = 122, 81%). Median time from first negative CSF culture to final surgical procedure was 14 days (IQR 10-21 days). Median duration of intravenous (IV) antibiotic use duration was 19 days (IQR 12-28 days). For 84 infections addressed by IDSA guidelines, 7 (8%) met guidelines and 61 (73%) had longer duration of IV antibiotic use than recommended.

CONCLUSIONS

Surgical treatment for infection frequently adheres to IDSA guidelines of shunt removal with external ventricular drain placement followed by new shunt insertion. However, duration of IV antibiotic use in CSF shunt infection treatment was consistently longer than recommended by the 2004 IDSA guidelines.

Research into the Physiology of Cerebrospinal Fluid Reaches a New Horizon: Intimate Exchange between Cerebrospinal Fluid and Interstitial Fluid May Contribute to Maintenance of Homeostasis in the Central Nervous System

Cerebrospinal fluid (CSF) plays an essential role in maintaining the homeostasis of the central nervous system. The functions of CSF include: (1) buoyancy of the brain, spinal cord, and nerves; (2) volume adjustment in the cranial cavity; (3) nutrient transport; (4) protein or peptide transport; (5) brain volume regulation through osmoregulation; (6) buffering effect against external forces; (7) signal transduction; (8) drug transport; (9) immune system control; (10) elimination of metabolites and unnecessary substances; and finally (11) cooling of heat generated by neural activity. For CSF to fully mediate these functions, fluid-like movement in the ventricles and subarachnoid space is necessary. Furthermore, the relationship between the behaviors of CSF and interstitial fluid in the brain and spinal cord is important. In this review, we will present classical studies on CSF circulation from its discovery over 2,000 years ago, and will subsequently introduce functions that were recently discovered such as CSF production and absorption, water molecule movement in the interstitial space, exchange between interstitial fluid and CSF, and drainage of CSF and interstitial fluid into both the venous and the lymphatic systems. Finally, we will summarize future challenges in research. This review includes articles published up to February 2016.

A Review of Clinical Outcomes for Gait and Other Variables in the Surgical Treatment of Idiopathic Normal Pressure Hydrocephalus

BACKGROUND

Idiopathic normal pressure hydrocephalus (INPH) is a treatable cause of gait disturbance, cognitive impairment, and urinary incontinence. This clinical triad of symptoms occurs in association with ventriculomegaly and normal cerebrospinal fluid (CSF) pressure. Although the treatment outcomes after CSF shunting for INPH have improved significantly since its first description in 1965, shortcomings in our understanding still remain. Not all INPH patients exhibit clinical improvement after shunting, and it is challenging to identify patients who are more likely to benefit from shunting.

METHODS

The Cochrane Library, Medline, Embase, and PubMed databases were searched for English-language publications between 1965 and October 2015. Reference lists of publications were also manually searched for additional publications.

RESULTS

The findings of this review indicate that, despite efforts to improve patient selection, the degree of clinical improvement after shunting continues to demonstrate significant variability both within and between studies. These discrepancies in treatment outcomes are the result of controversies in 3 distinct but interrelated domains: the underlying pathophysiology of INPH, the diagnosis of INPH, and the identification of likely shunt-responders.

CONCLUSIONS

This review focuses on these 3 areas and their relation to surgical treatment outcomes. Despite the limitations of published outcome studies and limitations in our understanding of INPH pathophysiology, shunting is a safe and effective means of achieving meaningful clinical improvement in most patients with INPH.

Changes in Rat Brain Tissue Microstructure and Stiffness during the Development of Experimental Obstructive Hydrocephalus

Understanding neural injury in hydrocephalus and how the brain changes during the course of the disease in-vivo remain unclear. This study describes brain deformation, microstructural and mechanical properties changes during obstructive hydrocephalus development in a rat model using multimodal magnetic resonance (MR) imaging. Hydrocephalus was induced in eight Sprague-Dawley rats (4 weeks old) by injecting a kaolin suspension into the cisterna magna. Six sham-injected rats were used as controls. MR imaging (9.4T, Bruker) was performed 1 day before, and at 3, 7 and 16 days post injection. T2-weighted MR images were collected to quantify brain deformation. MR elastography was used to measure brain stiffness, and diffusion tensor imaging (DTI) was conducted to observe brain tissue microstructure. Results showed that the enlargement of the ventricular system was associated with a decrease in the cortical gray matter thickness and caudate-putamen cross-sectional area (P < 0.001, for both), an alteration of the corpus callosum and periventricular white matter microstructure (CC+PVWM) and rearrangement of the cortical gray matter microstructure (P < 0.001, for both), while compression without gross microstructural alteration was evident in the caudate-putamen and ventral internal capsule (P < 0.001, for both). During hydrocephalus development, increased space between the white matter tracts was observed in the CC+PVWM (P < 0.001), while a decrease in space was observed for the ventral internal capsule (P < 0.001). For the cortical gray matter, an increase in extracellular tissue water was significantly associated with a decrease in tissue stiffness (P = 0.001). To conclude, this study characterizes the temporal changes in tissue microstructure, water content and stiffness in different brain regions and their association with ventricular enlargement. In summary, whilst diffusion changes were larger and statistically significant for majority of the brain regions studied, the changes in mechanical properties were modest. Moreover, the effect of ventricular enlargement is not limited to the CC+PVWM and ventral internal capsule, the extent of microstructural changes vary between brain regions, and there is regional and temporal variation in brain tissue stiffness during hydrocephalus development.

Evaluation of the Production and Absorption of Cerebrospinal Fluid

The traditional hypothesis of cerebrospinal fluid (CSF) hydrodynamics presumes that CSF is primarily produced in the choroid plexus (CP), then flows from the ventricles into the subarachnoid spaces, and mainly reabsorbed in the arachnoid granulations. This hypothesis is necessary to reconsider in view of recent research and clinical observations. This literature review presents numerous evidence for a new hypothesis of CSF hydrodynamics-(1) A significantly strong relationship exists between the CSF and interstitial fluid (IF), (2) CSF and IF are mainly produced and absorbed in the parenchymal capillaries of the brain and spinal cord. A considerable amount of CSF and IF are also absorbed by the lymphatic system, and (3) CSF movement is not unidirectional flow. It is only local mixing and diffusion.

Limitations of Neuroendoscopic Treatment for Pediatric Hydrocephalus and Considerations from Future Perspectives

Neuroendoscopy has become common in the field of pediatric neurosurgery. As an alternative procedure to cerebrospinal fluid shunt, endoscopic third ventriculostomy has been the routine surgical treatment for obstructive hydrocephalus. However, the indication is still debatable in infantile periods. The predictors of late failure and how to manage are still unknown. Recently, the remarkable results of endoscopic choroid plexus coagulation in combination with third ventriculostomy, reported from experiences in Africa, present puzzling complexity. The current data on the role of neuroendoscopic surgery for pediatric hydrocephalus is reported with discussion of its limitations and future perspectives, in this review.

Differential vulnerability of white matter structures to experimental infantile hydrocephalus detected by diffusion tensor imaging

PURPOSE

The differential vulnerability of white matter (WM) to acute and chronic infantile hydrocephalus and the related effects of early and late reservoir treatment are unknown, but diffusion tensor imaging (DTI) could provide this information. Thus, we characterized WM integrity using DTI in a clinically relevant model.

METHODS

Obstructive hydrocephalus was induced in 2-week-old felines by intracisternal kaolin injection. Ventricular reservoirs were placed 1 (early) or 2 (late) weeks post-kaolin and tapped frequently based solely on neurological deficit. Hydrocephalic and age-matched control animals were sacrificed 12 weeks postreservoir. WM integrity was evaluated in the optic system, corpus callosum, and internal capsule prereservoir and every 3 weeks using DTI. Analyses were grouped as acute (<6 weeks) or chronic (≥6 weeks).

RESULTS

In the corpus callosum during acute stages, fractional anisotropy (FA) decreased significantly with early and late reservoir placement (p = 0.0008 and 0.0008, respectively), and diffusivity increased significantly in early (axial, radial, and mean diffusivity, p = 0.0026, 0.0012, and 0.0002, respectively) and late (radial and mean diffusivity, p = 0.01 and 0.0038, respectively) groups. Chronically, the corpus callosum was thinned and not detectable by DTI. FA was significantly lower in the optic chiasm and tracts (p = 0.0496 and 0.0052, respectively) with late but not early reservoir placement. In the internal capsule, FA in both reservoir groups increased significantly with age (p < 0.05) but diffusivity remained unchanged.

CONCLUSIONS

All hydrocephalic animals treated with intermittent ventricular reservoir tapping demonstrated progressive ventriculomegaly. Both reservoir groups demonstrated WM integrity loss, with the CC the most vulnerable and the optic system the most resilient.

Electrospun polyurethane as an alternative ventricular catheter and in vitro model of shunt obstruction

Intracranial pressure and volume vary considerably between hydrocephalic patients, and with age, health and haemodynamic status; if left untreated, intracranial pressure rises and the ventricular system expands to accommodate the excess cerebrospinal fluid, with significant morbidity and mortality. Cerebrospinal fluid shunts in use today have a high incidence of failure with shunt obstruction being the most serious. Conventional proximal shunt catheters are made from poly(dimethyl)siloxane, the walls of which are perforated with holes for the cerebrospinal fluid to pass through. The limited range of catheters, in terms of material selection and flow distribution, is responsible in large part for their poor performance.

In this study, we present an alternative design of proximal catheter made of electrospun polyether urethane, and evaluate its performance in the presence of glial cells, which are responsible for shunt blockage. The viability and growth of cells on catheter materials such as poly(dimethyl)siloxane and polyurethane in the form of cast films, microfibrous mats and porous sponges were studied in the presence of proteins present in cerebrospinal fluid after 48 h and 96 h in culture. The numbers of viable cells on each substrate were comparable to untreated poly(dimethyl)siloxane, both in the presence and absence of serum proteins found in cerebrospinal fluid. A cell culture model of shunt obstruction was developed in which cells on electrospun polyether urethane catheters were subjected to flow during culture in vitro, and the degree of obstruction quantified in terms of hydraulic permeability after static and perfusion culture. The results indicate that a catheter made of electrospun polyether urethane would be able to maintain cerebrospinal fluid flow even with the presence of cells for the time period chosen for this study. These findings have implications for the design and deployment of microporous shunt catheter systems for the treatment of hydrocephalus.

Neural stem cells: are they the hope of a better life for patients with fetal-onset hydrocephalus?

I was honored to be awarded the Casey Holter Essay Prize in 2013 by the Society for Research into Hydrocephalus and Spina Bifida. The purpose of the prize is to encourage original thinking in a way to improve the care of individuals with spina bifida and hydrocephalus. Having kept this purpose in mind, I have chosen the title: Neural stem cells, are they the hope of a better life for patients with fetal-onset hydrocephalus? The aim is to review and discuss some of the most recent and relevant findings regarding mechanisms leading to both hydrocephalus and abnormal neuro/gliogenesis. By looking at these outcome studies, it is hoped that we will recognize the potential use of neural stem cells in the treatment of hydrocephalus, and so prevent the disease or diminish/repair the associated brain damage.

Few Patient, Treatment, and Diagnostic or Microbiological Factors, Except Complications and Intermittent Negative Cerebrospinal Fluid (CSF) Cultures During First CSF Shunt Infection, Are Associated With Reinfection

BACKGROUND

The relationship between first and subsequent cerebrospinal fluid (CSF) shunt infections is poorly understood. By understanding the factors associated with increased risk of reinfection, researchers may provide optimal treatment strategies at the time of first infection. The objective of this study was to describe and compare children with and without CSF shunt reinfection.

METHODS

A retrospective cohort study was performed among 118 children who underwent initial CSF shunt placement and developed first CSF shunt infection. The primary outcome variable was CSF shunt reinfection. Patient risk factors and medical and surgical management of initial CSF shunt placement and first CSF shunt infection were compared between children with and without reinfection.

RESULTS

Of 118 children with first infection, 31 (26%) developed a reinfection during the study period (overall median follow-up, 2096 days). Factors associated with reinfection in this cohort included ventriculoatrial or complex shunt at initial CSF shunt placement, complications after first CSF shunt infection, and intermittent negative CSF cultures.

CONCLUSIONS

Few patient or treatment factors were associated with reinfection. Factors associated with difficult-to-treat first CSF shunt infection, including complications after first CSF shunt infection and intermittent negative CSF cultures, were associated with reinfection. Clinicians who treat patients with unusual CSF shunts or more difficult first infections should have a high index of suspicion for reinfection after treatment is completed.

Evaluation of microbial bacterial and fungal diversity in cerebrospinal fluid shunt infection

Background

Cerebrospinal fluid shunt infection can be recalcitrant. Recurrence is common despite appropriate therapy for the pathogens identified by culture. Improved diagnostic and therapeutic approaches are required, and culture-independent molecular approaches to cerebrospinal fluid shunt infections have not been described.

Objectives

To identify the bacteria and fungi present in cerebrospinal fluid from children with cerebrospinal fluid shunt infection using a high-throughput sequencing approach, and to compare those results to those from negative controls and conventional culture.

Methods

This descriptive study included eight children ≤18 years old undergoing treatment for culture-identified cerebrospinal fluid shunt infection. After routine aerobic culture of each cerebrospinal fluid sample, deoxyribonucleic acid (DNA) extraction was followed by amplification of the bacterial 16S rRNA gene and the fungal ITS DNA region tag-encoded FLX-Titanium amplicon pyrosequencing and microbial phylogenetic analysis.

Results

The microbiota analyses for the initial cerebrospinal fluid samples from all eight infections identified a variety of bacteria and fungi, many of which did not grow in conventional culture. Detection by conventional culture did not predict the relative abundance of an organism by pyrosequencing, but in all cases, at least one bacterial taxon was detected by both conventional culture and pyrosequencing. Individual bacterial species fluctuated in relative abundance but remained above the limits of detection during infection treatment.

Conclusions

Numerous bacterial and fungal organisms were detected in these cerebrospinal fluid shunt infections, even during and after treatment, indicating diverse and recalcitrant shunt microbiota. In evaluating cerebrospinal fluid shunt infection, fungal and anaerobic bacterial cultures should be considered in addition to aerobic bacterial cultures, and culture-independent approaches offer a promising alternative diagnostic approach. More effective treatment of cerebrospinal fluid shunt infections is needed to reduce unacceptably high rates of reinfection, and this work suggests that one effective strategy may be reduction of the diverse microbiota present in infection.

Abnormal development of NG2+PDGFR-α+ neural progenitor cells leads to neonatal hydrocephalus in a ciliopathy mouse model

Hydrocephalus is a common neurological disorder leading to expansion of the cerebral ventricles and is associated with significant morbidity and mortality. Most neonatal cases are of unknown etiology and are likely to display complex inheritance involving multiple genes and environmental factors. Identifying molecular mechanisms for neonatal hydrocephalus and developing non-invasive treatment modalities are high priorities. Here we employ a hydrocephalic mouse model of the human ciliopathy Bardet-Biedl Syndrome (BBS) and identify a role for neural progenitors in the pathogenesis of neonatal hydrocephalus. We found that hydrocephalus in this mouse model is caused by aberrant PDGFRα signaling, resulting in increased apoptosis and impaired proliferation of NG2⁺PDGFRα⁺ neural progenitors. Targeting this pathway with lithium treatment rescued NG2⁺PDGFRα⁺ progenitor cell proliferation in BBS mutant mice, reducing ventricular volume. Our findings demonstrate that neural progenitors are critical in the pathogenesis of neonatal hydrocephalus and we identify novel therapeutic targets for this common neurological disorder.

Changes in heart rate variability in a premature infant with hydrocephalus

Objective To define changes of heart rate variability in premature infant with hydrocephalus before and after drainage procedure. Study Design The authors report a case of a premature infant with hydrocephalus with analysis of heart rate variability before and after drainage procedure. Three subsequent recordings of the electrocardiography and heart rate variability were done: the first at the age of 22 days before insertion of ventriculoperitoneal shunt, the second at the age of 36 days with functional shunt, the third at the age of 71 days (before discharge). Results Before drainage operation, there was reduced heart rate variability in time and spectral domains, and sympathetic activity was dominant. After surgery, an increase in heart rate variability parameters was found, particularly with spectral analysis. The ratio of low-frequency/high-frequency band and relative power of the low-frequency band decreased, reflecting enhanced parasympathetic activity. Conclusion Results of the heart rate variability analysis in a preterm infant with hydrocephalus before and after drainage procedure showed marked improvement in chronotropic cardiac regulation. Evaluation of heart rate variability in premature infants with hydrocephalus with increased intracranial pressure can be an additional method for monitoring of cardiac dysregulation and improvement of the cardiovascular control after successful drainage procedure.

The assessment of intracranial dynamics by transcranial Doppler sonography in perioperative period in paediatric hydrocephalus

PURPOSE

To evaluate Doppler parameters of anterior cerebral artery (ACA) and relationship to morphological parameters of cerebral ventricles and periventricular brain tissue in paediatric hydrocephalus before and after drainage procedure.

METHODS

Forty newborns with hydrocephalus were evaluated before and after the drainage procedure. The morphological parameters of brain (ventricular index, width of ventricles, haemorrhagic lesions, asymmetric ventricular dilatation and dynamics of ventricles) were measured by transcranial ultrasonography. The haemodynamic parameters of ACA (peak systolic blood flow velocity, end-diastolic blood flow velocity and resistance index/RI/) were evaluated by Doppler ultrasonography. The correlation between morphological and haemodynamic parameters was analysed.

RESULTS

We found significant decrease of ventricular dilatation, which was accompanied with significant decrease of basal and compressive RI-ACA after drainage procedure. The correlation between basal RI-ACA, compressive RI-ACA and the dynamics of ventricular dilatation was not significant before and after drainage operation, as well. The significant correlation between preoperative basal RI-ACA, postoperative compressive RI-ACA and asymmetry of cerebral ventricles was confirmed. Statistical analysis showed significant correlation between basal RI-ACA, compressive RI-ACA and haemorrhagic lesions after drainage operation.

CONCLUSIONS

The results of our study showed the alteration of Doppler parameters of cerebral circulation in newborns with hydrocephalus before the drainage procedure. The successful drainage operation leads to the improvement of haemodynamic parameters of cerebral circulation. However, the statistical analysis showed the influence of some intracranial factors-the asymmetry of dilatation of lateral cerebral ventricles and periventricular haemorrhagic lesions on the Doppler parameters of cerebral circulation.

The hydrokinetic parameters of shunts for hydrocephalus might be inadequate

Long-term treatment of hydrocephalus continues to be dismal. Shunting is the neurosurgical procedure more frequently associated with complications, which are mostly related with dysfunctions of the shunting device, rather than to mishaps of the rather simple surgical procedure. Overdrainage and underdrainage are the most common dysfunctions; of them, overdrainage is a conspicuous companion of most devices. Even when literally hundreds of different models have been proposed, developed, and tested, overdrainage has plagued all shunts for the last 60 years. Several investigations have demonstrated that changes in the posture of the subject induce unavoidable and drastic differences of intraventricular hydrokinetic pressure and cerebrospinal fluid (CSF) drainage through the shunt. Of all the parameters that participate in the pathophysiology of hydrocephalus, the only invariable one is cerebrospinal fluid production at a constant rate of approximately 0.35 ml/min. However, this feature has not been considered in the design of currently available shunts. Our experimental and clinical studies have shown that a simple shunt, whose drainage capacity complies with this unique parameter, would prevent most complications of shunting for hydrocephalus.

Reinfection following initial cerebrospinal fluid shunt infection

OBJECT

Significant variation exists in the surgical and medical management of CSF shunt infection. The objectives of this study were to determine CSF shunt reinfection rates following initial CSF shunt infection in a large patient cohort and to determine management, patient, hospital, and surgeon factors associated with CSF shunt reinfection.

METHODS

This retrospective cohort study included children who were in the Pediatric Health Information System (PHIS) database, who ranged in age from 0 to 18 years, and who underwent uncomplicated initial CSF shunt placement in addition to treatment for initial CSF shunt infection between January 1, 2001, and December 31, 2008. The outcome was CSF shunt reinfection within 6 months. The main predictor variable of interest was surgical approach to treatment of first infection, which was determined for 483 patients. Covariates included patient, hospital, surgeon, and other management factors.

RESULTS

The PHIS database includes 675 children with initial CSF shunt infection. Surgical approach to treatment of the initial CSF shunt infection was determined for 483 children (71.6%). The surgical approach was primarily shunt removal/new shunt placement (in 286 children [59.2%]), but a substantial number underwent externalization (59 children [12.2%]), of whom a subset went on to have the externalized shunt removed and a new shunt placed (17 children [3.5% overall]). Other approaches included nonsurgical management (64 children [13.3%]) and complete shunt removal without shunt replacement (74 children [15.3%]). The 6-month reinfection rate was 14.8% (100 of 675 patients). The median time from infection to reinfection was 21 days (interquartile range [IQR] 5-58 days). Children with reinfection had less time between shunt placement and initial infection (median 50 vs 79 days, p = 0.06). No differences between those with and without reinfection were seen in patient factors (patient age at either shunt placement or initial infection, sex, race/ethnicity, payer, indication for shunt, number of comorbidities, distal shunt location, and number of shunt revisions at first infection); hospital volume; surgeon volume; or other management factors (for example, duration of intravenous antibiotic use). Nonsurgical management was associated with reinfection, and complete shunt removal was negatively associated with reinfection. However, reinfection rates did not differ between the 2 most common surgical approaches: shunt removal/new shunt placement (44 [15.4%] of 286; 95% CI 11.4%-20.1%) and externalization (total 12 [20.3%] of 59; 95% CI 11.0%-32.8%). Externalization followed by shunt removal/new shunt placement (5 [29.4%] of 17; 95% CI 10.3%-56.0%) and nonsurgical management (15 [23.4%] of 64; 95% CI 13.8%-35.7%) had higher, but nonstatistically significant, reinfection rates. The length of stay was shorter for nonsurgical management.

CONCLUSIONS

Surgical approach to treatment of initial CSF shunt infection was not associated with reinfection in this large cohort of patients.

Reactive astrocytosis, microgliosis and inflammation in rats with neonatal hydrocephalus

The deleterious effects of hydrocephalus, a disorder that primarily affects children, include reactive astrocytosis, microgliosis and inflammatory responses; however, the roles that these mechanisms play in the pathophysiology of hydrocephalus are still not clear in terms of cytopathology and gene expression. Therefore we have examined neuroinflammation at both the cellular and the molecular levels in an experimental model of neonatal obstructive hydrocephalus. On post-natal day 1, rats received an intracisternal injection of kaolin to induce hydrocephalus; control animals received saline injections. Prior to sacrifice on post-natal day 22, animals underwent magnetic resonance imaging to quantify ventricular enlargement, and the parietal cortex was harvested for analysis. Immunohistochemistry and light microscopy were performed on 5 hydrocephalic and 5 control animals; another set of 5 hydrocephalic and 5 control animals underwent molecular testing with Western blots and a gene microarray. Scoring of immunoreactivity on a 4-point ranking scale for GFAP and Iba-1 demonstrated an increase in reactive astrocytes and reactive microglia respectively in the hydrocephalic animals compared to controls (2.90±0.11 vs. 0.28±0.26; 2.91±0.11 vs. 0.58±0.23, respectively). Western blots confirmed these results. Microarray analysis identified significant (1.5-fold) changes in 1729 of 33,951 genes, including 26 genes out of 185 genes (26/185) in the cytokine-cytokine receptor interaction pathway, antigen processing and presentation pathways (15/66), and the apoptosis pathway (10/69). Collectively, these results demonstrate alterations in normal physiology and an up-regulation of the inflammatory response. These findings lead to a better understanding of neonatal hydrocephalus and begin to form a baseline for future treatments that may reverse these effects.

Who will care for me next? Transitioning to adulthood with hydrocephalus

OBJECTIVES

Hydrocephalus is a prototypical chronic condition that follows children into adulthood. The objectives of this study were to (1) review how the health care needs of young adults with hydrocephalus are not being met, (2) estimate the numbers of adults with childhood-onset hydrocephalus, (3) describe a novel program to provide care for young adults with hydrocephalus and other chronic pediatric conditions, and (4) propose national strategies to promote successful hydrocephalus transition care.

RESULTS

Adults with hydrocephalus need continuous access to expert surgical and medical providers. Existing care models fail to meet this need. The number of young adults who have hydrocephalus, are aged 18 to 35 and need treatment in the United States is predicted to exceed 40000 annually within the next 2 decades. We are developing integrated teams of pediatric and adult medical and surgical specialists to provide continuous, coordinated, comprehensive care for individuals with hydrocephalus in a pediatric setting. This setting will train our future physician workforce on optimal transition care. Coordinated national efforts are also needed.

CONCLUSIONS

Providers need to implement appropriate management and transition care for individuals with hydrocephalus. We must work at local and national levels to transform the care model, improve the quality of health care delivery, and improve outcomes for young adults with hydrocephalus.

Intra-abdominal pressure: the neglected variable in selecting the ventriculoperitoneal shunt for treating hydrocephalus

OBJECTIVE

In the selection of a ventriculoperitoneal cerebrospinal fluid shunt, the intra-abdominal pressure (IAP) is traditionally neglected as a result of the idea that its value is close to 0 mmHg. Our aim was to explore the relationship between body mass index (BMI) and IAP with the goal of providing clinically relevant data that could help neurosurgeons to estimate IAP and select the appropriate shunt for patients with hydrocephalus and especially those with normal-pressure hydrocephalus syndrome.

METHODS

Sixty patients requiring the placement of a ventriculoperitoneal shunt were included in the study. We determined weight, BMI, and IAP. IAP was measured through an intraperitoneal catheter during the shunt surgery. To determine whether a linear relationship existed between quantitative variables, linear regression analysis was used.

RESULTS

BMI was 28.1 +/- 4.8 kg/m2. Eighteen patients (30%) had normal weight, 21 (35%) were moderately overweight, and 21 (35%) were obese. IAP was related to patient BMI. A significant positive linear correlation was identified between BMI and IAP (r = 0.52; P = 0.018) with a slope of 0.31 (P < 0.001) and an intercept of -5.5.

CONCLUSION

In our study, we determined that IAP had a strong positive linear relationship with BMI. This correlation was independent of sex. An IAP of 0 mmHg can, therefore, only be assumed for patients with a normal BMI who are recumbent. In obese or overweight patients, neurosurgeons should take IAP into account when selecting both the most adequate differential pressure valve to be implanted and in which distal cavity to place the distal catheter to avoid shunt underdrainage induced by high IAP.