CSF proteomic analysis in patients with normal pressure hydrocephalus selected for the shunt: CSF biomarkers of response to surgical treatment

Cerebrospinal fluid and venous biomarkers of shunt-responsive idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a neurodegenerative disease and dementia subtype involving disturbed cerebrospinal fluid (CSF) homeostasis. Patients with iNPH may improve clinically following CSF diversion through shunt surgery, but it remains a challenge to predict which patients respond to shunting. It has been proposed that CSF and blood biomarkers may be used to predict shunt response in iNPH.

OBJECTIVE

To conduct a systematic review and meta-analysis to identify which CSF and venous biomarkers predict shunt-responsive iNPH most accurately.

METHODS

Original studies that investigate the use of CSF and venous biomarkers to predict shunt response were searched using the following databases: Embase, MEDLINE, Scopus, PubMed, Google Scholar, and JSTOR. Included studies were assessed using the ROBINS-I tool, and eligible studies were evaluated utilising univariate meta-analyses.

RESULTS

The study included 13 studies; seven addressed lumbar CSF levels of amyloid-β 1-42, nine studies CSF levels of Total-Tau, six studies CSF levels of Phosphorylated-Tau, and seven studies miscellaneous biomarkers, proteomics, and genotyping. A meta-analysis of six eligible studies conducted for amyloid-β 1-42, Total-Tau, and Phosphorylated-Tau demonstrated significantly increased lumbar CSF Phosphorylated-Tau (- 0.55 SMD, p = 0.04) and Total-Tau (- 0.50 SMD, p = 0.02) in shunt-non-responsive iNPH, though no differences were seen between shunt responders and non-responders for amyloid-β 1-42 (- 0.26 SMD, p = 0.55) or the other included biomarkers.

CONCLUSION

This meta-analysis found that lumbar CSF levels of Phosphorylated-Tau and Total-Tau are significantly increased in shunt non-responsive iNPH compared to shunt-responsive iNPH. The other biomarkers, including amyloid-β 1-42, did not significantly differentiate shunt-responsive from shunt-non-responsive iNPH. More studies on the Tau proteins examining sensitivity and specificity at different cut-off levels are needed for a robust analysis of the diagnostic efficiency of the Tau proteins.

P-Tau as prognostic marker in long term follow up for patients with shunted iNPH

Objective: Diagnosis of idiopathic Normal Pressure Hydrocephalus (iNPH) relies solely on clinical and radiological criteria while, unlike other neurological diseases, the analysis of cerebrospinal fluid markers is not used in clinical practice. Nevertheless, the overlapping of neurodegenerative diseases affects the long-term shunt efficacy and this occurrence should be detected before surgery. Therefore, we performed this study in order to assess the correlation between pre-surgical levels of CSF Beta Amyloid protein, Total Tau protein and Phospho-Tau protein with long-term clinical outcome. Methods: Between March 2012 and May 2016 we prospective evaluated all patients with iNPH according to guidelines criteria and we analysed CSF concentration of these proteins before and during surgery. Two years after surgery we evaluated iNPH score for all patients, grouping them in shunt responders and non-responders. Results: A total of 117 patients were included: Tap Test non-responders were 58 and at two years we had 35 shunt responders and 15 shunt non-responders. We found a significative difference between shunt-responders and shunt non-responders for pre surgical T-Tau (p: 0.02) and for P-Tau (p: 0.01). All the proteins were significantly associated with clinical outcome after surgery with different cut-off values; in particular, having a 'low' value of T-Tau, P-Tau and Aβ1-42 resulted in favourable outcome after surgery. Conclusions: Low level of P-Tau is a useful CSF biochemical prognostic factor for good clinical outcome at least two years after shunt; meanwhile a lower Aβ1-42 might suggest that the pathophysiology of iNPH could have something in common with other neurodegenerative diseases of the elderly.

Behavioral and Biochemical Features of the Course and Surgical Treatment of Experimental Obstructive Hydrocephalus in Young Rats

INTRODUCTION

Hydrocephalus is a multifactorial disease, affecting the dynamics of cerebrospinal fluid (CSF) and leading to severe neurological impairment in children; in spite of the recent advances in hydrocephalus research, it has many physiopathological aspects that still remain poorly understood, especially after treatment.

OBJECTIVES

To analyze the clinical, radiological, histopathological, and biochemical aspects of kaolin-induced hydrocephalus in an experimental model, both in the acute phase and after shunt treatment, by means of behavioral tests, magnetic resonance imaging (MRI) scans, histopathological studies, and level of inflammatory interleukins in the CSF.

METHODS

Seven-day-old Wistar rats were used and subdivided into three subgroups: treated hydrocephalic (n = 24), untreated hydrocephalic (n = 17), and controls (n = 5). The hydrocephalic groups underwent cisternal injection of 15% kaolin for induction of hydrocephalus at 7 days of age. The treated group was submitted to a ventricular-subcutaneous shunt (VSCS) 1 week after induction. All animals were euthanized at 21 days of age. They underwent motor function and memory testing as well as brain MRI scans. Histopathological analysis for glial fibrillary acidic protein and Ki-67 was done, and CSF was collected for measurement of IL-1β, IL-6, and TNF-α.

RESULTS

The average time to reach the water maze platform was highest in the untreated hydrocephalic group. The magnetization transfer rates were 37.21 and 33.76 before and after shunting, respectively. The mean astrocyte counts were 2.45, 1.36, and 90.5 for shunted, untreated, and control animals, respectively. The mean CSF IL-1β concentrations were 62.3 and 249.6 pg/mL, the average IL-6 levels were 104.2 and 364.7 pg/mL, and the average TNF-α values were 4.9 and 170.5 pg/mL for the treated hydrocephalic group and the untreated group, respectively.

CONCLUSIONS

Pups treated with a CSF shunt showed better performance on memory tests. VSCS did not revert demyelination caused by hydrocephalus. Likewise, reactive astrocytosis and cell proliferation over the germinal matrix were not reversed after shunting. Hydrocephalic animals had raised levels of inflammatory interleukins, which returned to normal after treatment.

Current concepts on the pathophysiology of idiopathic chronic adult hydrocephalus: Are we facing another neurodegenerative disease?

INTRODUCTION

Since its description five decades ago, the pathophysiology of idiopathic chronic adult hydrocephalus (iCAH) has been traditionally related to the effect that ventricular dilatation exerts on the structures surrounding the ventricular system. However, altered cerebral blood flow, especially a reduction in the CSF turnover rate, are starting to be considered the main pathophysiological elements of this disease.

DEVELOPMENT

Compression of the pyramidal tract, the frontostriatal and frontoreticular circuits, and the paraventricular fibres of the superior longitudinal fasciculus have all been reported in iCAH. At the level of the corpus callosum, gliosis replaces a number of commissural tracts. Cerebral blood flow is also altered, showing a periventricular watershed region limited by the subependymal arteries and the perforating branches of the major arteries of the anterior cerebral circulation. The CSF turnover rate is decreased by 75%, leading to the reduced clearance of neurotoxins and the interruption of neuroendocrine and paracrine signalling in the CSF.

CONCLUSIONS

iCAH presents as a complex nosological entity, in which the effects of subcortical microangiopathy and reduced CSF turnover play a key role. According to its pathophysiology, it is simpler to think of iCAH more as a neurodegenerative disease, such as Alzheimer disease or Binswanger disease than as the classical concept of hydrocephalus.

The MiRNA Journey from Theory to Practice as a CNS Biomarker

MicroRNAs (miRNAs), small nucleotide sequences that control gene transcription, have the potential to serve an expanded function as indicators in the diagnosis and progression of neurological disorders. Studies involving debilitating neurological diseases such as, Alzheimer's disease, multiple sclerosis, traumatic brain injuries, Parkinson's disease and CNS tumors, already provide validation for their clinical diagnostic use. These small nucleotide sequences have several features, making them favorable candidates as biomarkers, including function in multiple tissues, stability in bodily fluids, a role in pathogenesis, and the ability to be detected early in the disease course. Cerebrospinal fluid, with its cell-free environment, collection process that minimizes tissue damage, and direct contact with the brain and spinal cord, is a promising source of miRNA in the diagnosis of many neurological disorders. Despite the advantages of miRNA analysis, current analytic technology is not yet affordable as a clinically viable diagnostic tool and requires standardization. The goal of this review is to explore the prospective use of CSF miRNA as a reliable and affordable biomarker for different neurological disorders.

An update on research priorities in hydrocephalus: overview of the third National Institutes of Health-sponsored symposium "Opportunities for Hydrocephalus Research: Pathways to Better Outcomes"

Building on previous National Institutes of Health-sponsored symposia on hydrocephalus research, "Opportunities for Hydrocephalus Research: Pathways to Better Outcomes" was held in Seattle, Washington, July 9-11, 2012. Plenary sessions were organized into four major themes, each with two subtopics: Causes of Hydrocephalus (Genetics and Pathophysiological Modifications); Diagnosis of Hydrocephalus (Biomarkers and Neuroimaging); Treatment of Hydrocephalus (Bioengineering Advances and Surgical Treatments); and Outcome in Hydrocephalus (Neuropsychological and Neurological). International experts gave plenary talks, and extensive group discussions were held for each of the major themes. The conference emphasized patient-centered care and translational research, with the main objective to arrive at a consensus on priorities in hydrocephalus that have the potential to impact patient care in the next 5 years. The current state of hydrocephalus research and treatment was presented, and the following priorities for research were recommended for each theme. 1) Causes of Hydrocephalus-CSF absorption, production, and related drug therapies; pathogenesis of human hydrocephalus; improved animal and in vitro models of hydrocephalus; developmental and macromolecular transport mechanisms; biomechanical changes in hydrocephalus; and age-dependent mechanisms in the development of hydrocephalus. 2) Diagnosis of Hydrocephalus-implementation of a standardized set of protocols and a shared repository of technical information; prospective studies of multimodal techniques including MRI and CSF biomarkers to test potential pharmacological treatments; and quantitative and cost-effective CSF assessment techniques. 3) Treatment of Hydrocephalus-improved bioengineering efforts to reduce proximal catheter and overall shunt failure; external or implantable diagnostics and support for the biological infrastructure research that informs these efforts; and evidence-based surgical standardization with longitudinal metrics to validate or refute implemented practices, procedures, or tests. 4) Outcome in Hydrocephalus-development of specific, reliable batteries with metrics focused on the hydrocephalic patient; measurements of neurocognitive outcome and quality-of-life measures that are adaptable, trackable across the growth spectrum, and applicable cross-culturally; development of comparison metrics against normal aging and sensitive screening tools to diagnose idiopathic normal pressure hydrocephalus against appropriate normative age-based data; better understanding of the incidence and prevalence of hydrocephalus within both pediatric and adult populations; and comparisons of aging patterns in adults with hydrocephalus against normal aging patterns.

Use of cerebrospinal fluid amyloid-β and total tau protein to predict favorable surgical outcomes in patients with idiopathic normal pressure hydrocephalus

Object

The prognostic value of CSF biomarkers in patients with idiopathic normal pressure hydrocephalus (iNPH) has not been adequately studied to date. The aim of this study was to identify CSF markers of favorable surgical outcome in patients with iNPH undergoing the insertion of a ventriculoperitoneal shunt.

Methods

Ventricular CSF was collected intraoperatively from 22 patients with iNPH and enzyme-linked immunosorbent assay was used to analyze the levels of amyloid-β 1–42 (Aβ1–42) and total tau protein. The Black grading scale was used to assess outcomes at 6 months. Receiver operating characteristic (ROC) curves were obtained and discriminant function analysis was undertaken to provide sensitivity and specificity figures for each marker as well as their combination.

Results

The mean age of the patients was 71.45 years (± 9.5 years [SD]). Follow-up was achieved in 21 patients. Seventeen patients had a favorable outcome and 4 patients had unfavorable outcome at 6 months. An Aβ1–42 level of 180 pg/ml had a sensitivity of 35% and a specificity of 20% for predicting a favorable outcome at 6 months. A total tau level of 767 pg/ml will have a sensitivity of 17% and a specificity of 20% for predicting a favorable outcome at 6 months. A combination of Aβ1–42 and total tau levels predicted favorable outcomes with a sensitivity of 80% and specificity of 82.4%.

Conclusions

In this pilot study a combination of Aβ1–42 levels and total tau protein levels predicted favorable surgical outcomes at 6 months with adequate accuracy to be of clinical use. Further study in a larger group with longer follow-up is warranted.

Cerebrospinal fluid biomarkers in idiopathic normal pressure hydrocephalus

The diagnosis of idiopathic normal pressure hydrocephalus (iNPH) is still challenging. Alzheimer's disease (AD), along with vascular dementia, the most important differential diagnosis for iNPH, has several potential cerebrospinal fluid (CSF) biomarkers which might help in the selection of patients for shunt treatment. The aim of this study was to compare a battery of CSF biomarkers including well-known AD-related proteins with CSF from patients with suspected iNPH collected from the external lumbar drainage test (ELD). A total of 35 patients with suspected iNPH patients were evaluated with ELD. CSF was collected in the beginning of the test, and the concentrations of total tau, ptau(181), Aβ(42), NFL, TNF-α, TGFβ1, and VEGF were analysed by ELISA. Twenty-six patients had a positive ELD result-that is, their gait symptoms improved; 9 patients had negative ELD. The levels of all analyzed CSF biomarkers were similar between the groups and none of them predicted the ELD result in these patients. Contrary to expectations lumbar CSF TNF-α concentration was low in iNPH patients.