EFNS guidelines on disease-specific CSF investigations

Cerebrospinal Fluid Analysis in Rheumatological Diseases with Neuropsychiatric Complications and Manifestations: A Narrative Review

The analysis of cerebrospinal fluid (CSF) remains a valuable diagnostic tool in the evaluation of inflammatory and infectious conditions involving the brain, spinal cord, and meninges. Since many rheumatic inflammatory diseases can involve the central and peripheral nervous system, the aims of this narrative review were to summarize the latest evidence on the use of CSF analysis in the field of neuropsychiatric manifestations of rheumatic diseases. Routine CSF parameters were taken into consideration for this review: appearance; total protein and cellular content (pleocytosis); lactate and/or glucose; CSF/serum albumin quotient; intrathecal synthesis of IgG. Data regarding the role of CSF analysis in the clinical management of neuropsychiatric systemic lupus erythematosus, primary Sjogren's syndrome, rheumatoid arthritis, and Behçet's syndrome are presented. Although no disease-specific picture has been identified, CSF analysis remains a useful diagnostic tool to confirm the presence of a neuro-inflammatory state or, conversely, to exclude the concomitant presence of other inflammatory/infectious diseases affecting the CNS in the context of systemic rheumatologic conditions.

Intrathecal CD8+CD20+ T Cells in Primary Progressive Multiple Sclerosis

BACKGROUND AND OBJECTIVE

Despite accumulating evidence of intrathecal inflammation in patients with primary progressive multiple sclerosis (PPMS), immunomodulatory and suppressive treatment strategies have proven unsuccessful. With this study, we investigated the involvement of CD20⁺ T cells and the effect of dimethyl fumarate on CD20⁺ T cells in PPMS.

METHODS

The main outcomes in this observational, case-control study were flow cytometry assessments of blood and CSF CD20⁺ T cells and ELISA measurements of myelin basic protein and neurofilament light chain in untreated patients with PPMS and patients treated for 48 weeks with dimethyl fumarate or placebo. MRI measures included new and enlarging T2-weighted lesions over 48 weeks and lesion, normal-appearing white matter, cortical, and thalamic volume.

RESULTS

Assessing CD20⁺ T cells in patients with PPMS and controls showed an increased percentage of CD20⁺ T cells in the blood of untreated patients and a strong enrichment in the CSF. In addition, a higher frequency of CD8⁺CD20⁺ T cells in the CSF correlated with a higher concentration of myelin basic protein and T2-weighted lesion volume and with a lower normal-appearing white matter and thalamus volume. Furthermore, CD8⁺CD20⁺ T cells were associated with the development of new T2 lesions. After 48 weeks of treatment with dimethyl fumarate, total T cells in CSF were reduced; however, CD20⁺ T cells were unaffected.

DISCUSSION

This study shows an association between intrathecal CD8⁺CD20⁺ T cells, white matter injury, and thalamic atrophy in PPMS, suggesting a role of CD8⁺CD20⁺ T cells in the immunopathogenesis of PPMS. The results also suggest that limited efficacy of dimethyl fumarate in PPMS may, at least partly, be a consequence of failure to suppress CD8⁺CD20⁺ T cells in CSF.

Plasma and cerebrospinal fluid concentrations of neurofilament light protein correlate in patients with idiopathic normal pressure hydrocephalus

BACKGROUND

Neurofilament light chain protein (NFL), a marker of neuronal axonal degeneration, is increased in cerebrospinal fluid (CSF) of patients with idiopathic normal pressure hydrocephalus (iNPH). Assays for analysis of NFL in plasma are now widely available but plasma NFL has not been reported in iNPH patients. Our aim was to examine plasma NFL in iNPH patients and to evaluate the correlation between plasma and CSF levels, and whether NFL levels are associated with clinical symptoms and outcome after shunt surgery.

METHODS

Fifty iNPH patients with median age 73 who had their symptoms assessed with the iNPH scale and plasma and CSF NFL sampled pre- and median 9 months post-operatively. CSF plasma was compared with 50 healthy controls (HC) matched for age and gender. Concentrations of NFL were determined in plasma using an in-house Simoa method and in CSF using a commercially available ELISA method.

RESULTS

Plasma NFL was elevated in patients with iNPH compared to HC (iNPH: 45 (30-64) pg/mL; HC: 33 (26-50) (median; Q1-Q3), p = 0.029). Plasma and CSF NFL concentrations correlated in iNPH patients both pre- and postoperatively (r = 0.67 and 0.72, p < 0.001). We found only weak correlations between plasma or CSF NFL and clinical symptoms and no associations with outcome. A postoperative NFL increase was seen in CSF but not in plasma.

CONCLUSIONS

Plasma NFL is increased in iNPH patients and concentrations correlate with CSF NFL implying that plasma NFL can be used to assess evidence of axonal degeneration in iNPH. This finding opens a window for plasma samples to be used in future studies of other biomarkers in iNPH. NFL is probably not a very useful marker of symptomatology or for prediction of outcome in iNPH.

Changes in pNFH Levels in Cerebrospinal Fluid and Motor Evolution after the Loading Dose with Nusinersen in Different Types of Spinal Muscular Atrophy

Aim and Objectives: The objective of our retrospective study was to investigate the changes in pNFH levels in cerebrospinal fluid, which is a reliable marker of neuronal damage, after the loading dose of nusinersen in different types of spinal muscular atrophy. Materials and Methods: We analyzed the spinal muscular atrophy types, the number of copies of the SMN2 gene, and the progression of the motor status using specific motor function scales in a group of 38 patients with spinal muscular atrophy types 1, 2, and 3. Results: We found a significant inverse correlation between pNFH levels and patient age, progress on functional motor scales, and nusinersen administration. Our results also revealed that the neurofilament levels in the cerebrospinal fluid were higher in patients with 2 SMN2 copies than those with more than 2 copies, although the association was not statistically significant due to the abnormal distribution of the values. Conclusions: We identified several predictors of favorable evolution under nusinersen treatment, including spinal muscular atrophy type 1, children aged ≤ 30 months, and the presence of only 2 copies of SMN2. Our study provides important insights into the use of pNFH as a biomarker to monitor disease progression and responses to treatment in patients with spinal muscular atrophy.

Exploring the role of cerebrospinal fluid as analyte in neurologic disorders

The cerebrospinal fluid (CSF) is a clear ultrafiltrate of blood that envelopes and protects the central nervous system while regulating neuronal function through the maintenance of interstitial fluid homeostasis in the brain. Due to its anatomic location and physiological functions, the CSF can provide a reliable source of biomarkers for the diagnosis and treatment monitoring of different neurological diseases, including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and primary and secondary brain malignancies. The incorporation of CSF biomarkers into the drug discovery and development can improve the efficiency of drug development and increase the chances of success. This review aims to consolidate the current use of CSF biomarkers in clinical practice and explore future perspectives for the field.

Shared CSF Biomarker Profile in Idiopathic Normal Pressure Hydrocephalus and Subcortical Small Vessel Disease

Introduction

In this study, we examine similarities and differences between 52 patients with idiopathic normal pressure hydrocephalus (iNPH) and 17 patients with subcortical small vessel disease (SSVD), in comparison to 28 healthy controls (HCs) by a panel of cerebrospinal fluid (CSF) biomarkers.

Methods

We analyzed soluble amyloid precursor protein alpha (sAPPα) and beta (sAPPβ), Aβ isoforms −38, −40, and −42, neurofilament light protein (NFL), glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), matrix metalloproteinases (MMP −1, −2, −3, −9, and −10), and tissue inhibitors of metalloproteinase 1 (TIMP1). Radiological signs of white matter damage were scored using the age-related white matter changes (ARWMC) scale.

Results

All amyloid fragments were reduced in iNPH and SSVD (p &lt; 0.05), although more in iNPH than in SSVD in comparison to HC. iNPH and SSVD showed comparable elevations of NFL, MBP, and GFAP (p &lt; 0.05). MMPs were similar in all three groups except for MMP-10, which was increased in iNPH and SSVD. Patients with iNPH had larger ventricles and fewer WMCs than patients with SSVD.

Conclusion

The results indicate that patients with iNPH and SSVD share common features of subcortical neuronal degeneration, demyelination, and astroglial response. The reduction in all APP-derived proteins characterizing iNPH patients is also present, indicating that SSVD encompasses similar pathophysiological phenomena as iNPH.

CSF biomarkers for prion diseases

Recently, clinical trials of human prion disease (HPD) treatments have begun in many countries, and the therapeutic window of these trials focuses mainly on the early stage of the disease. Furthermore, few studies have examined the role of biomarkers at the early stage. According to the World Health Organization, the clinical diagnostic criteria for HPDs include clinical findings, cerebrospinal fluid (CSF) protein markers, and electroencephalography (EEG). In contrast, the UK and European clinical diagnostic criteria include a combination of clinical findings, 14-3-3 protein in the CSF, magnetic resonance imaging-diffusion-weighted imaging (MRI-DWI), and EEG. Moreover, recent advancements in laboratory testing and MRI-DWI have improved the accuracy of diagnostics used for prion diseases. However, according to MRI-DWI data, patients with rapidly progressing dementia are sometimes misdiagnosed with HPD due to the high-intensity areas detected in their brains. Thus, analyzing the CSF biomarkers is critical to diagnose accurately different diseases. CSF biomarkers are investigated using a biochemical approach or the protein amplification methods that utilize the unique properties of prion proteins and the ability of PrP^Sc to induce a conformational change. The biochemical markers include the 14-3-3 and total tau proteins of the CSF. In contrast, the protein amplification methods include the protein misfolding cyclic amplification assay and real-time quaking-induced conversion (RT-QuIC) assay. The RT-QuIC analysis of the CSF has been proved to be a highly sensitive and specific test for identifying sporadic HPD forms; for this reason, it was included in the diagnostic criteria.

Neurofilament light chain as a biomarker for diagnosis of multiple sclerosis

The treatments for multiple sclerosis (MS) have improved over the past 25 years, but now the main question for physicians is deciding who should receive treatment, for how long, and when to switch to other options. These decisions are typically based on treatment tolerance and a reasonable expectation of long-term efficacy. A significant unmet need is the lack of accurate laboratory measurements for diagnosis, and monitoring of treatment response, including deterioration and disease progression. There are few validated biomarkers for MS, and in practice, physicians employ two biomarkers discovered fifty years ago for MS diagnosis, often in combination with MRI scans. These biomarkers are intrathecal IgG and oligoclonal bands in the CSF (cerebrospinal fluid). Neurofilament light chain (NfL) is a relatively new biomarker for MS diagnosis and follow up. Neurofilaments are neuron-specific cytoskeleton proteins that can be measured in various body compartments. NfL is a new biomarker for MS that can be measured in serum samples, but this still needs further study to specify the laboratory cut-off values in clinical practice. In the present review we discuss the evidence for NfL as a reliable biomarker for the early detection and management of MS. Moreover, we highlight the correlation between MRI and NfL, and ask whether they can be combined.

Metabolic drift in the aging nervous system is reflected in human cerebrospinal fluid

Chronic diseases affecting the central nervous system (CNS) like Alzheimer's or Parkinson's disease typically develop with advanced chronological age. Yet, aging at the metabolic level has been explored only sporadically in humans using biofluids in close proximity to the CNS such as the cerebrospinal fluid (CSF). We have used an untargeted liquid chromatography high-resolution mass spectrometry (LC-HRMS) based metabolomics approach to measure the levels of metabolites in the CSF of non-neurological control subjects in the age of 20 up to 74. Using a random forest-based feature selection strategy, we extracted 69 features that were strongly related to age (p_age < 0.001, r_age = 0.762, R²_{Boruta age} = 0.764). Combining an in-house library of known substances with in silico chemical classification and functional semantic annotation we successfully assigned putative annotations to 59 out of the 69 CSF metabolites. We found alterations in metabolites related to the Cytochrome P450 system, perturbations in the tryptophan and kynurenine pathways, metabolites associated with cellular energy (NAD+, ADP), mitochondrial and ribosomal metabolisms, neurological dysfunction, and an increase of adverse microbial metabolites. Taken together our results point at a key role for metabolites found in CSF related to the Cytochrome P450 system as most often associated with metabolic aging.

Perioperative management of endoscopic transsphenoidal pituitary surgery

The contemporary embrace of endoscopic technology in the approach to the anterior skull base has altered the perioperative landscape for patients requiring pituitary surgery. Utility of a multi-disciplinary unit in management decisions facilitates the delivery of optimal care. Evolution of technology and surgical expertise in pituitary surgery mandates ongoing review of all components of the care central to these patients. The many areas of potential variability in the pre, intra and post-operative timeline of pituitary surgery are readily identifiable. Core undertakings and contemporary controversies in the peri-operative management of patients undergoing endoscopic transsphenoidal pituitary surgery are assessed against the available literature with a view to providing guidance for the best evidence-based practice.

Dimethyl fumarate decreases neurofilament light chain in CSF and blood of treatment naïve relapsing MS patients

OBJECTIVES

In a prospective phase IV trial of the first-line oral treatment dimethyl fumarate (DMF), we examined dynamics of neurofilament light (NFL) chain in serum, plasma and cerebrospinal fluid (CSF) samples collected over 12 months from relapsing-remitting multiple sclerosis (RRMS) patients. NFL changes were related to disease activity.

METHODS

We examined NFL levels by single-molecule array in 88 CSF, 348 plasma and 131 sera from treatment-naïve RRMS patients (n=52), healthy controls (n=23) and a placebo group matched by age, sex and NFL (n=52). Plasma/sera were collected at baseline, and 1, 3, 6 and 12 months after DMF. CSF samples were collected at baseline and 12 months after DMF.

RESULTS

NFL concentration in CSF, plasma and serum correlated highly (p<0.0001 for all), but plasma levels were only 76.9% of paired serum concentration. After 12 months of DMF treatment, NFL concentration decreased by 73%, 69% and 55% in the CSF, serum and plasma (p<0.0001, respectively). Significant reduction in blood was observed after 6 and 12 months treatment compared with baseline (p<0.01 and p<0.0001, respectively) and to placebo (p<0.0001). Patients with NFL above the 807.5 pg/mL cut-off in CSF had 5.0-times relative risk of disease activity (p<0.001).

CONCLUSIONS

This study provides Class II evidence that first-line DMF reduces NFL in both blood and CSF after 6 months and normalises CSF levels in 73% of patients. High NFL concentration in CSF after a year reflected disease activity. NFL levels were higher in serum than in plasma, which should be considered when NFL is used as a biomarker.

Neurofilament light levels are associated with long-term outcomes in multiple sclerosis

Background:

Neurofilament light chain (NfL) is a promising marker of disease activity/treatment response in multiple sclerosis (MS), although its predictive value for long-term clinical outcomes remains unclear.

Objective:

We measured NfL from a phase 3 trial in relapsing-remitting MS and investigated its association with outcomes after 8 and 15 years.

Methods:

NfL concentrations were measured by single molecule array assay in cerebrospinal fluid (CSF) from MS patients (n = 235) in a 2-year randomized clinical trial (RCT) of intramuscular interferon β-1a, and in serum (n = 164) from the extension study.

Results:

Year 2 CSF and Year 3 serum NfL were associated with brain parenchymal fraction (BPF) change over 8 years (p < 0.0001, r = −0.46; p < 0.05. r = −0.36, respectively) and were predictive of reaching Expanded Disability Status Scale (EDSS) ⩾ 6.0 at Year 8 (odds ratio (OR) (upper vs lower tertile) = 3.4; 95% confidence interval (CI) = 1.2–9.9, p < 0.05; OR = 11.0, 95% CI = 2.0–114.6; p < 0.01, respectively). Serum NfL concentration (Year 4) was predictive of reaching EDSS score ⩾6.0 at 15 years (OR (upper vs lower tertile) = 4.9; 95% CI = 1.4–20.4; p < 0.05). NfL concentrations were complementary to 2-year BPF change in predicting long-term outcomes.

Conclusion:

Serum and CSF NfL concentrations were associated with long-term clinical outcomes in MS patients and are promising biomarkers for disease severity stratification supporting treatment decisions.

Guidelines for CSF Processing and Biobanking: Impact on the Identification and Development of Optimal CSF Protein Biomarkers

The field of neurological diseases strongly needs biomarkers for early diagnosis and optimal stratification of patients in clinical trials or to monitor disease progression. Cerebrospinal fluid (CSF) is one of the main sources for the identification of novel protein biomarkers for neurological diseases. Despite the enormous efforts employed to identify novel CSF biomarkers, the high variability observed across different studies has hampered their validation and implementation in clinical practice. Such variability is partly caused by the effect of different pre-analytical confounding factors on protein stability, highlighting the importance to develop and comply with standardized operating procedures. In this chapter, we describe the international consensus pre-analytical guidelines for CSF processing and biobanking that have been established during the last decade, with a special focus on the influence of pre-analytical confounders on the global CSF proteome. In addition, we provide novel results on the influence of different delayed storage and freeze/thaw conditions on the CSF proteome using two novel large multiplex protein arrays (SOMAscan and Olink). Compliance to consensus guidelines will likely facilitate the successful development and implementation of CSF protein biomarkers in both research and clinical settings, ultimately facilitating the successful development of disease-modifying therapies.

Recommendations for cerebrospinal fluid analysis

Diseases of the central nervous system (CNS) mean for the human organism a potentially dangerous situation. An investigation of cerebrospinal fluid (CSF) provides important information about a character of CNS impairment in the decision-making diagnostic and therapeutic algorithm. The authors present a brief overview of available cerebrospinal fluid assays, shortened indication criteria, a recommended algorithm of CSF assessment in different suspected diseases, and a view of the external quality system. The whole portfolio of obtainable CSF methodology is further subdivided according to the adequate choice into the first and inevitable basic routine panel, and following complicated analyses of highly specialized character. The basic panel is considered for standard laboratories, the complete specialized assessment should be provided by a super-consulting laboratory.

Rapidly Progressing Sporadic Creutzfeldt-Jakob Disease Presenting as a Stroke

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare, fatal human prion disease that is characterized by progressive dementia and neurologic degeneration. It can mimic multiple other neurological disorders, and a high index of clinical suspicion is necessary to make a diagnosis. A 74-year-old woman with a 3-month history of a stroke and progressive neurologic deterioration was found to have sCJD. She expired within a week of her diagnosis. Autopsy revealed spongiform encephalopathy consistent with prion disease, and genetic analysis revealed 129 polymorphism and no pathologic mutation, confirming the diagnosis of nonfamilial human prion disease. No pathologic evidence of a stroke was found. Awareness of the disease by clinicians is important not only at the time of initial presentation but also during the following months. Since there is no treatment, invasive medical procedures should be limited to only those that are required for either diagnosis or hospice care.

Vascular diseases and bleedings

Diseases of the central nervous system that are caused by an underlying vascular pathology typically result in either hemorrhage or ischemia. Most prominent entities include spontaneous subarachnoid hemorrhage, spontaneous intracerebral hemorrhage, and ischemic stroke. For anatomic reasons, cerebrospinal fluid (CSF) qualifies as body fluid for the exploration of biomarkers in these disorders. Even though in subarachnoid hemorrhage a few CSF parameters have been established for routine diagnostic purposes, there is still an unmet need and broad interest in the identification of molecules that would allow further insight into disease mechanisms and supplement patients' medical care. This chapter provides an overview on what is presently known about CSF biomarkers in spontaneous subarachnoid hemorrhage, spontaneous intracerebral hemorrhage, and ischemic stroke. We recapitulate current evidence on established diagnostic tests, discuss the role of various CSF molecules in the pathophysiology of these diseases, and illuminate their potential use in future clinical practice. Furthermore, we address methodologic aspects as well as shortcomings of research in this field.

The cerebrospinal fluid and barriers - anatomic and physiologic considerations

The cerebrospinal fluid (CSF) space consists of the intracerebral ventricles, subarachnoid spaces of the spine and brain (e.g., cisterns and sulci), and the central spinal cord canal. The CSF protects the central nervous system (CNS) in different ways involving metabolic homeostasis, supply of nutrients, functioning as lymphatic system, and regulation of intracranial pressure. CSF is produced by the choroid plexus, brain interstitium, and meninges, and it circulates in a craniocaudal direction from ventricles to spinal subarachnoid space from where it is removed via craniocaudal lymphatic routes and the venous system. The CSF is renewed 3-5 times daily and its molecular constituents are mainly blood-derived (80%), while the remainder consists of brain-derived and intrathecally produced molecules (20%). The CSF space is separated from the vascular system by the blood-CSF barrier (BCB), whereas the blood-brain barrier (BBB), responsible for maintaining the homeostasis of the brain, is located between brain parenchyma and vascular system. Although both barriers have similar functions, they differ with regard to their morphologic and functional properties. Both barrier systems are permeable not only for small molecules, but also for macromolecules and circulating cells. The transport of molecules across the BBB and BCB is regulated by passive diffusion (e.g., albumin, immunoglobulins) and facilitated or active transport (e.g., glucose). The extracellular space volume, potassium buffering, CSF circulation, and interstitial fluid absorption are mainly regulated by aquaporin-4 channels, which are abundantly located at the blood-brain and brain-CSF interfaces. The composition of CSF shows a high dynamic range, and the levels of distinct proteins vary due to several influencing factors, such as site of production (brain or blood-derived), site of sampling (ventricular or lumbar), CSF flow rate (BCB function), diurnal fluctuations of CSF production rate, and finally, molecular size of blood-derived proteins (IgM vs. albumin) and circadian rhythm (glucose, prostaglandin D synthase). Alterations of lumbar CSF are mainly influenced by processes of the CNS located adjacent to the ventricular and spinal CSF space and less by pathologies in cortical areas remote from the ventricles.

Defining active progressive multiple sclerosis

Background:

It is unknown whether disease activity according to consensus criteria (magnetic resonance imaging activity or clinical relapses) associate with cerebrospinal fluid (CSF) changes in progressive multiple sclerosis (MS).

Objective:

To compare CSF biomarkers in active and inactive progressive MS according to consensus criteria.

Methods:

Neurofilament light chain (NFL), myelin basic protein (MBP), IgG-index, chitinase-3-like-1 (CHI3L1), matrix metalloproteinase-9 (MMP-9), chemokine CXCL13, terminal complement complex, leukocyte counts and nitric oxide metabolites were measured in primary ( n = 26) and secondary progressive MS ( n = 26) and healthy controls ( n = 24).

Results:

Progressive MS patients had higher CSF cell counts, IgG-index, CHI3L1, MMP-9, CXCL13, NFL and MBP concentrations. Active patients were younger and had higher NFL, CXCL13 and MMP-9 concentrations than inactive patients. Patients with active disease according to consensus criteria or detectable CXCL13 or MMP-9 in CSF were defined as having combined active progressive MS. These patients had increased CSF cell counts, IgG-index and MBP, NFL and CHI3L1 concentrations. Combined inactive patients only had increased IgG-index and MBP concentrations.

Conclusion:

Patients with combined active progressive MS show evidence of inflammation, demyelination and neuronal/axonal damage, whereas the remaining patients mainly show evidence of active demyelination. This challenges the idea that neurodegeneration independent of inflammation is crucial in disease progression.

Comparison of three analytical platforms for quantification of the neurofilament light chain in blood samples: ELISA, electrochemiluminescence immunoassay and Simoa

BACKGROUND

Neuronal damage is the morphological substrate of persisting neurological disability. Neurofilaments (Nf) are specific cytoskeletal proteins of neurons and their quantification has shown encouraging results as a biomarker for axonal injury.

METHODS

We aimed at comparing a widely used conventional ELISA for Nf light chain (NfL) with an electrochemiluminescence-based method (ECL assay) and a newly developed single-molecule array (Simoa) method in clinically relevant cerebrospinal fluid (CSF) and serum samples.

RESULTS

Analytical sensitivity was 0.62 pg/mL for Simoa, 15.6 pg/mL for the ECL assay, and 78.0 pg/mL for the ELISA. Correlations between paired CSF and serum samples were strongest for Simoa (r=0.88, p<0.001) and the ECL assay (r=0.78, p<0.001) and weaker for ELISA measurements (r=0.38, p=0.030). CSF NfL measurements between the platforms were highly correlated (r=1.0, p<0.001). Serum NfL levels were highly related between ECL assay and Simoa (r=0.86, p<0.001), and this was less visible between ELISA-ECL assay (r=0.41, p=0.018) and ELISA-Simoa (r=0.43, p=0.013). Multiple sclerosis (MS) patients had significantly higher serum NfL levels than controls when measured with Simoa (p=0.001) but not with the other platforms.

CONCLUSIONS

We found Simoa to be more sensitive than ELISA or the ECL assay. Our results support the feasibility of quantifying NfL in serum; the results correlate with the more-established CSF NfL test. The highly sensitive Simoa technology deserves further studies in larger patient cohorts to clarify whether serum NfL could be used in the future to measure disease severity and determine prognosis or response to treatment interventions in neurological diseases.

Neoplastic leptomeningeal disease masquerading as central serous retinopathy. A case report

A 69-year-old man became aware of people’s speech being out of synch with their lip movements alongside persistent headaches, both of which progressively worsened. A few weeks later, he developed progressive and painless visual loss in one eye. Initial neurological evaluation, inflammatory markers and head computed tomography scan were normal. Ophthalmological examination and OCT scan revealed right macular subretinal fluid with choroidal indentation, which prompted urgent further investigations including head MRI revealing extensive leptomeningeal disease. The patient continued to deteriorate and deceased shortly afterwards.

This is the first reported case of neoplastic leptomeningeal disease presenting with loss of vision due to choroidal metastasis with localised exudative retinal detachment. Diagnosing neoplastic leptomeningeal disease requires a high index of suspicion from the treating physician. Symptoms may be nonspecific and/or subtle. Combining cerebrospinal fluid cytology from lumbar puncture with contrast-enhanced magnetic resonance imaging of the brain is considered the optimal diagnostic approach.

Neurofilament Light Chain Determination from Peripheral Blood Samples

The loss of neurological function is closely related to axonal damage. Neurofilament subunits are concentrated in neurons and axons and have emerged as promising biomarkers for neurodegeneration. Electrochemiluminescence (ECL) based assays are known to be of superior sensitivity and require less sample volume than conventional ELISAs. Here, we describe a highly sensitive ECL based immunoassay for quantification of neurofilament light chain (NfL) in blood and CSF.

Antibody biomarkers in CNS demyelinating diseases - a long and winding road

Over several decades, studies sought potential markers to diagnose and to predict the clinical course of central nervous system (CNS) demyelinating disorders, especially in multiple sclerosis, acute disseminated encephalomyelitis and neuromyelitis optica spectrum disorders. Reliable biomarkers would ensure correct diagnoses, determine future disease evolvements, stratify patients for appropriate treatments and monitor disease activity and treatment effects - in summary, meet the longing for personalized medicine in these diseases. Out of a plethora of potential biomarker candidates antibodies have turned (again) into the scientific focus, due to pivotal immunological and neuropathological findings in the past 20 years. A major breakthrough and stimulus for further research was the identification of anti-aquaporin-4 antibodies in neuromyelitis optica. Various other myelin and non-myelin antigens were investigated in detail for diagnostic and prognostic purposes, such as antibodies to myelin oligodendrocyte glycoprotein or to the potassium channel KIR4.1. Further, the use of biopharmaceutical treatments in multiple sclerosis led to intense research activities to identify anti-treatment neutralizing antibodies and their clinical consequences. This review briefly summarizes the current knowledge on antibodies in the diagnosis, prognosis, disease and treatment monitoring of CNS demyelinating disorders.

Effect of epileptic seizures on the cerebrospinal fluid--A systematic retrospective analysis

OBJECTIVE

Analyses of the cerebrospinal fluid (CSF) are obligatory when epileptic seizures manifest for the first time in order to exclude life-threatening causes or treatable diseases such as acute infections or autoimmune encephalitis. However, there are only few systematic investigations on the effect of seizures themselves on CSF parameters and the significance of these parameters in differential diagnosis.

METHODS

CSF samples of 309 patients with epileptic and 10 with psychogenic seizures were retrospectively analyzed. CSF samples were collected between 1999 and 2008. Cell counts, the albumin quotient, lactate and Tau-protein levels were determined. Findings were correlated with seizure types, seizure etiology (symptomatic, cryptogenic, occasional seizure), and seizure duration.

RESULTS

Pathological findings were only observed in patients with epileptic but not with psychogenic seizures. The lactate concentration was elevated in 14%, the albumin quotient in 34%, and the Tau protein level in 36% of CSF samples. Cell counts were only slightly elevated in 6% of patients. Different seizure types influenced all parameters except for the cell count: In status epilepticus highest, in simple partial seizures lowest values were seen. Symptomatic partial and generalized epileptic seizures had significantly higher Tau-protein levels than cryptogenic partial seizures. In patients with repetitive and occasional epileptic seizures, higher Tau-protein levels were seen than in those with psychogenic seizures. Duration of epileptic seizures was positively correlated with the albumin quotient, lactate and Tau-protein levels. High variability of investigated CSF parameters within each subgroup rendered a clear separation between epileptic and psychogenic seizures impossible.

SIGNIFICANCE

Elevated cell counts are infrequently observed in patients with epileptic seizures and should therefore not uncritically be interpreted as a postictal phenomenon. However, blood-CSF barrier disruption, increased glucose metabolism and elevation of neuronal damage markers are observed in considerable percentages of patients and depend on many factors such as etiology, seizure type and duration.

Biobanking of Cerebrospinal Fluid for Biomarker Analysis in Neurological Diseases

Cerebrospinal fluid (CSF) reflects pathophysiological aspects of neurological diseases, where neuroprotective strategies and biomarkers are urgently needed. Therefore, biobanking is very relevant for biomarker discovery and evaluation for these neurological diseases.An important aspect of CSF biobanking is quality control, needed for e.g. consistent patient follow-up and the exchange of patient samples between research centers. Systematic studies to address effects of pre-analytical and storage variation on a broad range of CSF proteins are needed and initiated.Important features of CSF biobanking are intensive collaboration in international networks and the tight application of standardized protocols. The current adoption of standardized protocols for CSF and blood collection and for biobanking of these samples, as presented in this chapter, enables biomarker studies in large cohorts of patients and controls.In conclusion, biomarker research in neurodegenerative diseases has entered a new era due to the collaborative and multicenter efforts of many groups. The streamlining of biobanking procedures, including sample collection, quality control, and the selection of optimal control groups for investigating biomarkers is an important improvement to perform high quality biomarker studies.

Association of lipocalin-type prostaglandin D synthase with disproportionately enlarged subarachnoid-space in idiopathic normal pressure hydrocephalus

Background

Idiopathic normal pressure hydrocephalus (iNPH) is a treatable cause of dementia, gait disturbance, and urinary incontinence in elderly patients with ventriculomegaly. Its unique morphological feature, called disproportionately enlarged subarachnoid-space hydrocephalus (DESH), may also be a diagnostic feature. Lipocalin-type prostaglandin D synthase (L-PGDS) is a major cerebrospinal fluid (CSF) protein produced by arachnoid cells, and its concentration in the CSF is reportedly decreased in iNPH. L-PGDS acts as a prostaglandin D2-producing enzyme and behaves as a chaperone to prevent the neurotoxic aggregation of amyloid beta (Aβ) implicated in Alzheimer’s disease, a major comorbidity of iNPH. The aim of this study was to confirm the L-PGDS decrease in DESH-type iNPH and to clarify its relationship with clinico-radiological features or other CSF biomarkers.

Methods

We evaluated 22 patients (age: 76.4 ± 4.4 y; males: 10, females: 12) referred for ventriculomegaly without CSF pathway obstruction, and conducted a CSF tap test to determine the surgical indication. CSF concentrations of L-PGDS, Aβ42, Aβ40, and total tau (t-tau) protein were determined using enzyme-linked immunosorbent assays. Clinical symptoms were evaluated by the iNPH grading scale, mini-mental state examination, frontal assessment battery (FAB), and timed up and go test. The extent of DESH was approximated by the callosal angle, and the severity of parenchymal damage was evaluated by the age-related white matter change (ARWMC) score.

Results

L-PGDS and t-tau levels in CSF were significantly decreased in DESH patients compared to non-DESH patients (p = 0.013 and p = 0.003, respectively). L-PGDS and t-tau showed a significant positive correlation (Spearman r = 0.753, p < 0.001). Among the clinico-radiological profiles, L-PGDS levels correlated positively with age (Spearman r = 0.602, p = 0.004), callosal angle (Spearman r = 0.592, p = 0.004), and ARWMC scores (Spearman r = 0.652, p = 0.001), but were negatively correlated with FAB scores (Spearman r = 0.641, p = 0.004).

Conclusions

Our data support the diagnostic value of L-PGDS as a CSF biomarker for iNPH and suggest a possible interaction between L-PGDS and tau protein. In addition, L-PGDS might work as a surrogate marker for DESH features, white matter damage, and frontal lobe dysfunction.

Post-seizure α-tocopherol treatment decreases neuroinflammation and neuronal degeneration induced by status epilepticus in rat hippocampus

Vitamin E (as α-tocopherol, α-T) was shown to have beneficial effects in epilepsy, mainly ascribed to its antioxidant properties. Besides radical-induced neurotoxicity, neuroinflammation is also involved in the pathophysiology of epilepsy, since neuroglial activation and cytokine production exacerbate seizure-induced neurotoxicity and contribute to epileptogenesis. We previously showed that α-T oral supplementation before inducing status epilepticus, markedly reduces astrocytic and microglial activation, neuronal cell death and oxidative stress in the hippocampus, as observed 4 days after seizure. In order to evaluate the possibility that such a neuroprotective and anti-inflammatory effect may also provide a strategy for an acute intervention in epilepsy, in this study, seizures were induced by single intaperitoneal injection of kainic acid and, starting from 3 h after status epilepticus, rats were treated with an intraperitoneal bolus of α-T (250 mg/kg b.w.; once a day) for 4 days, that was the time after which morphological and biochemical analyses were performed on hippocampus. Post-seizure α-T administration significantly reduced astrocytosis and microglia activation, and decreased neuron degeneration and spine loss; these effects were associated with the presence of a lowered lipid peroxidation in hippocampus. These results confirm and further emphasize the anti-inflammatory and neuroprotective role of α-T in kainic acid-induced epilepsy. Moreover, the findings show that post-seizure treatment with α-T provides an effective secondary prevention against post-seizure inflammation-induced brain damages and possibly against their epileptogenic effects.

The impact of pre-analytical variables on the stability of neurofilament proteins in CSF, determined by a novel validated SinglePlex Luminex assay and ELISA

BACKGROUND

Neurofilament (Nf) proteins have been shown to be promising biomarkers for monitoring and predicting disease progression for various neurological diseases. The aim of this study was to evaluate the effects of pre-analytical variables on the concentration of neurofilament heavy (NfH) and neurofilament light (NfL) proteins.

METHODS

For NfH an in-house newly-developed and validated SinglePlex Luminex assay was used; ELISA was used to analyze NfL.

RESULTS

For the NfL ELISA assay, the intra- and inter-assay variation was respectively, 1.5% and 16.7%. Analytical performance of the NfH SinglePlex Luminex assay in terms of sensitivity (6.6pg/mL), recovery in cerebrospinal fluid (CSF) (between 90 and 104%), linearity (from 6.6-1250pg/mL), and inter- and intra-assay variation (<8%) were good. Concentrations of both NfL and NfH appeared not negatively affected by blood contamination, repeated freeze-thaw cycles (up to 4), delayed processing (up to 24hours) and during long-term storage at -20°C, 4°C, and room temperature. A decrease in concentration was observed during storage of both neurofilament proteins up to 21days at 37°C, which was significant by day 5.

CONCLUSIONS

The newly developed NfH SinglePlex Luminex assay has a good sensitivity and is robust. Moreover, both NfH and NfL are stable under the most prevalent pre-analytical variations.

Optic neuritis as isolated manifestation of leptomeningeal carcinomatosis: a case report and systematic review of ocular manifestations of neoplastic meningitis

Introduction. Leptomeningeal carcinomatosis occurs in about 5% of cancer patients. Ocular involvement is a common clinical manifestation and often the presenting clinical feature. Materials and Methods. We report the case of a 52-year old lady with optic neuritis as isolated manifestation of neoplastic meningitis and a review of ocular involvement in neoplastic meningitis. Ocular symptoms were the presenting clinical feature in 34 patients (83%) out of 41 included in our review, the unique manifestation of meningeal carcinomatosis in 3 patients (7%). Visual loss was the presenting clinical manifestation in 17 patients (50%) and was the most common ocular symptom (70%). Other ocular signs were diplopia, ptosis, papilledema, anisocoria, exophthalmos, orbital pain, scotomas, hemianopsia, and nystagmus. Associated clinical symptoms were headache, altered consciousness, meningism, limb weakness, ataxia, dizziness, seizures, and other cranial nerves involvement. All patients except five underwent CSF examination which was normal in 1 patient, pleocytosis was found in 11 patients, increased protein levels were observed in 16 patients, and decreased glucose levels were found in 8 patients. Cytology was positive in 29 patients (76%). Conclusion. Meningeal carcinomatosis should be considered in patients with ocular symptoms even in the absence of other suggestive clinical symptoms.

Increased neurofilament light chain blood levels in neurodegenerative neurological diseases

Objective

Neuronal damage is the morphological substrate of persisting neurological disability. Neurofilaments (Nf) are cytoskeletal proteins of neurons and their release into cerebrospinal fluid has shown encouraging results as a biomarker for neurodegeneration. This study aimed to validate the quantification of the Nf light chain (NfL) in blood samples, as a biofluid source easily accessible for longitudinal studies.

Methods

We developed and applied a highly sensitive electrochemiluminescence (ECL) based immunoassay for quantification of NfL in blood and CSF.

Results

Patients with Alzheimer’s disease (AD) (30.8 pg/ml, n=20), Guillain-Barré-syndrome (GBS) (79.4 pg/ml, n=19) or amyotrophic lateral sclerosis (ALS) (95.4 pg/ml, n=46) had higher serum NfL values than a control group of neurological patients without evidence of structural CNS damage (control patients, CP) (4.4 pg/ml, n=68, p<0.0001 for each comparison, p=0.002 for AD patients) and healthy controls (HC) (3.3 pg/ml, n=67, p<0.0001). Similar differences were seen in corresponding CSF samples. CSF and serum levels correlated in AD (r=0.48, p=0.033), GBS (r=0.79, p<0.0001) and ALS (r=0.70, p<0.0001), but not in CP (r=0.11, p=0.3739). The sensitivity and specificity of serum NfL for separating ALS from healthy controls was 91.3% and 91.0%.

Conclusions

We developed and validated a novel ECL based sandwich immunoassay for the NfL protein in serum (NfL^Umea47:3); levels in ALS were more than 20-fold higher than in controls. Our data supports further longitudinal studies of serum NfL in neurodegenerative diseases as a potential biomarker of on-going disease progression, and as a potential surrogate to quantify effects of neuroprotective drugs in clinical trials.

Delayed diagnosis, range of severity, and multiple sleep comorbidities: a clinical and polysomnographic analysis of 100 patients of the innsbruck narcolepsy cohort

STUDY OBJECTIVES

Narcolepsy is reported to affect 26-56/100,000 in the general population. We aimed to describe clinical and polysomnographic features of a large narcolepsy cohort in order to comprehensively characterize the narcoleptic spectrum.

METHODS

We performed a chart- and polysomnographybased review of all narcolepsy patients of the Innsbruck narcolepsy cohort.

RESULTS

A total of 100 consecutive narcolepsy patients (87 with cataplexy [NC], 13 without cataplexy [N]) were included in the analysis. All subjects had either excessive daytime sleepiness or cataplexy as their initial presenting clinical feature. Age at symptom onset was 20 (6-69) years. Diagnostic delay was 6.5 (0-39) years. The complete narcolepsy tetrad was present in 36/100 patients; 28/100 patients had three cardinal symptoms; 29/100 had two; and 7/100 had only excessive daytime sleepiness. Severity varied broadly with respect to excessive daytime sleepiness (median Epworth Sleepiness Scale score: 18, range 10-24), cataplexy (8-point Likert scale: median 4.5, range 1-8), hypnagogic hallucinations (median 4.5, range 1-7), and sleep paralysis (median 3, range 1-7). Sleep comorbidity was highly prevalent and ranged from sleeprelated movement disorders (n = 55/100), parasomnias (n = 34/100), and sleeprelated breathing disorders (n = 24/100), to insomnia (n = 28/100). REM sleep without atonia or a periodic limb movement in sleep index > 5/h were present in most patients (90/100 and 75/100). A high percentage of narcoleptic patients in the present study had high frequency leg movements (35%) and excessive fragmentary myoclonus (22%). Of the narcolepsy patients with clinical features of REM sleep behavior disorder (RBD), 76.5% had EMG evidence for RBD on the multiple sleep latency test (MSLT), based on a standard cutoff of a minimum of 18% of 3-sec miniepochs.

CONCLUSION

This study is one of the largest monocentric polysomnographic studies to date of patients with narcolepsy and confirms the frequent comorbidity of narcolepsy with many other sleep disorders. Our study is the first to evaluate the percentage of patients with high frequency leg movements and excessive fragmentary myoclonus in narcolepsy and is the first to demonstrate EMG evidence of RBD in the MSLT. These findings add to the growing body of literature suggesting that motor instability is a key feature of narcolepsy.

Sensitivity and specificity of diagnostic accuracy in Alzheimer's disease: a synthesis of existing evidence

PURPOSE OF THE STUDY

This report synthesizes existing evidence to compare the accuracy of various Alzheimer's disease (AD) diagnostic approaches.

DESIGN AND METHODS

Meta-analyses and reviews of diagnostic accuracy of AD were identified through a search of the PubMed and Cochrane Library databases using the keyword combinations of "sensitivity specificity Alzheimer's disease diagnosis" and "accuracy of Alzheimer's disease diagnosis."

RESULTS

From 507 abstracts initially identified, 41 systematic reviews or meta-analyses were selected. Cerebrospinal fluid-tau demonstrated variable sensitivity (range 73.3%-100%) and specificity (range 70.0%-92.4%) in diagnosing AD when compared to neuropathological verification of clinical criteria for AD. Various positron emission tomography approaches showed a similar range of sensitivity (range 80.0%-100%) and specificity (range 62.0%-90%) as diagnostic protocols.

IMPLICATIONS

Issues that remain in the study of AD diagnosis include the need to determine the comparative effectiveness of diagnostic approaches. Variations in study quality make empirically derived conclusions about the diagnostic accuracy of existing approaches tenuous.

14-3-3 proteins, particularly of the epsilon isoform, are detectable in cerebrospinal fluids of cerebellar diseases in children

BACKGROUND

Detection of 14-3-3 proteins in cerebrospinal fluid (CSF) is a powerful tool for elucidating the mechanisms of neurological disorders. There have been useful studies on 14-3-3 CSF protein detection in Creutzfeldt-Jakob disease and other neurological disorders, but none on cerebellar diseases.

OBJECTIVE

To elucidate whether 14-3-3 CSF proteins are a sensitive biomarker of cerebellar disruption in children.

MATERIALS AND METHODS

We examined 14-3-3 CSF proteins by immunoblotting in seven patients with cerebellar disorders: two with acute cerebellitis, two with acute cerebellar ataxia, and three with cerebellar atrophy. We also investigated 14-3-3 CSF proteins in four cases of febrile seizure and three of influenza-related encephalopathy. Isoforms of 14-3-3 proteins were also identified using isoform-specific antibodies.

RESULTS

14-3-3 proteins were detected in CSF of six patients with cerebellar disorders, the exception being one with acute cerebellar ataxia caused by viral infection. Interestingly, only the 14-3-3 ε isoform was detected in two tested patients with cerebellar involvement. Moreover, longitudinal analysis of 14-3-3 CSF proteins in one patient with infantile neuroaxonal dystrophy showed that the 14-3-3 band density proportionally decreased when the cerebellar atrophy gradually progressed. Another CSF derived from a case of febrile seizure showed no 14-3-3 proteins, whereas all those derived from influenza-related encephalopathy demonstrated 14-3-3 CSF proteins with six isoforms.

CONCLUSIONS

This is the first report on 14-3-3 CSF proteins as a significant biomarker of cerebellar disruption, as well as other brain diseases. Since 14-3-3 ε is localized in the molecular layer of cerebellum, the unique detection of 14-3-3 ε may indicate cerebellar involvement in the brain.

Consensus definitions and application guidelines for control groups in cerebrospinal fluid biomarker studies in multiple sclerosis

The choice of appropriate control group(s) is critical in cerebrospinal fluid (CSF) biomarker research in multiple sclerosis (MS). There is a lack of definitions and nomenclature of different control groups and a rationalized application of different control groups. We here propose consensus definitions and nomenclature for the following groups: healthy controls (HCs), spinal anesthesia subjects (SASs), inflammatory neurological disease controls (INDCs), peripheral inflammatory neurological disease controls (PINDCs), non-inflammatory neurological controls (NINDCs), symptomatic controls (SCs). Furthermore, we discuss the application of these control groups in specific study designs, such as for diagnostic biomarker studies, prognostic biomarker studies and therapeutic response studies. Application of these uniform definitions will lead to better comparability of biomarker studies and optimal use of available resources. This will lead to improved quality of CSF biomarker research in MS and related disorders.

A comparative study of CSF neurofilament light and heavy chain protein in MS

BACKGROUND

There is a lack of reliable biomarkers of axonal degeneration. Neurofilaments are promising candidates to fulfil this task. We compared two highly sensitive assays to measure two subunits of the neurofilament protein (neurofilament light (NfL) and neurofilament heavy chain (NfH)).

METHODS

We evaluated the analytical and clinical performance of the UmanDiagnostics NF-light(®) enzyme-linked immunosorbent assay (ELISA) in the cerebrospinal fluid (CSF) of a group of 148 patients with clinically isolated syndrome (CIS) or multiple sclerosis (MS), and 72 controls. We compared our results with referring levels of our previously-developed CSF NfH(SMI35) assay.

RESULTS

Exposure to room temperature (up to 8 days) or repetitive thawing (up to 4 thaws) did not influence measurement of NfL concentrations. Values of NfL were higher in all disease stages of CIS/MS, in comparison to controls (p ≤ 0.001). NfL levels correlated with the Expanded Disability Status Scale (EDSS) score in patients with relapsing disease (r(s) = 0.31; p = 0.002), spinal cord relapses and with CSF markers of acute inflammation. The ability of NfL to distinguish patients from controls was greater than that of NfH(SMI35) in both CIS patients (p = 0.001) and all MS stages grouped together (p = 0.035).

CONCLUSIONS

NfL proved to be a stable protein, an important prerequisite for a reliable biomarker, and the NF-light(®) ELISA performed better in discriminating patients from controls, compared with the ECL-NfH(SMI35) immunoassay. We confirmed and expanded upon previous findings regarding neurofilaments as quantitative markers of neurodegeneration. Our results further support the role of neurofilaments as a potential surrogate measure for neuroprotective treatment in MS studies.

Neurofilament heavy chain and heat shock protein 70 as markers of seizure-related brain injury

PURPOSE

  Status epilepticus (SE) has deleterious effects on brain tissue, but whether brief recurrent seizures may also damage neurons represents a matter of controversy. Therefore, it remains a central area of epilepsy research to identify individuals at risk where disease progression can be potentially prevented. Biomarkers may serve as tools for such identification. Thus the present study aimed at analyzing the levels of heat shock protein 70 (HSP-70, also designated as HSPA1A) and neurofilament heavy chain protein (NfH(SMI35) ) in cerebrospinal fluid (CSF) of patients with seizures of different severity.

METHODS

  Forty-one patients were included, of whom 20 patients had a single generalized tonic-clonic seizure (GTCS) episode (SS), 11 had repetitive GTCS (RS), and 10 experienced convulsive SE. The control group consisted of 18 subjects. HSP-70 levels were measured using a conventional enzyme-linked immunosorbent assay (ELISA), whereas the NfH(SMI35) protein levels were detected by an electrochemiluminescence (ECL) immunoassay.

KEY FINDINGS

  Patients with SE (p < 0.001) and RS (p < 0.05) had significantly higher NfH(SMI35) levels than controls, and SE was associated with increased concentrations when compared with SS (p < 0.001). NfH(SMI35) levels in SS did not differ from controls. Patients with SE had significantly raised HSP-70 levels compared to RS (p < 0.05), SS (p < 0.05), and controls (p < 0.001). SS and RS did not differ from each or from controls. Levels of NfH(SMI35) and HSP-70 showed a significant correlation (r = 0.34; p = 0.007) in the group of all study subjects, which was not apparent when controls and patients with seizures were considered separately. The correlation between NfH(SMI35) and HSP-70 tended to be inverse in patients with SE, but it did not reach statistical significance (r = -0.3; p > 0.05).

SIGNIFICANCE

  Studying biochemical markers as additional quantitative tools for the measurement of neuronal damage (especially subclinical), complementary to available techniques of imaging, and clinical assessment might prove useful for identifying patients at risk of accumulating neuronal injury resulting from uncontrolled seizures. NfH(SMI35) and HSP-70 are of potential value as sensitive and specific biomarkers of seizure-related pathologic events. Future longitudinal studies are needed to monitor such patients by correlating biochemical, neuroimaging, and clinical methods of assessment.

Neurofilaments as biomarkers in multiple sclerosis

Neurodegeneration is the correlate of disease progression in multiple sclerosis (MS) and thus biological biomarkers that sensitively reflect this process are much needed. Neurofilament protein subunits are potential cerebrospinal fluid (CSF) biomarkers for disease progression in MS. We argue that the neurofilament light subunit can reflect acute axonal damage mediated by inflammatory mechanisms and can imply prognostic value for conversion from clinically isolated syndrome (CIS) to definite MS. The neurofilament heavy subunit may rather reflect chronic irreversible damage and has prognostic value for disease progression or disability. The neurofilament intermediate subunit has not yet been studied. Recent studies showing higher neurofilament light or heavy subunit levels to be altered upon treatment regimes indicate their potential clinical value in monitoring treatment or side effects. Future studies should be aimed at the optimisation, standardisation and interlaboratory implementation of the assays and address the predictive value of these biomarkers.

Cerebrospinal fluid markers in sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease (sCJD) is the commonest form of human prion diseases, accounting for about 85% of all cases. Current criteria for intra vitam diagnosis include a distinct phenotype, periodic sharp and slow-wave complexes at electroencephalography (EEG), and a positive 14-3-3-protein assay in the cerebrospinal fluid (CSF). In sCJD, the disease phenotype may vary, depending upon the genotype at codon 129 of the prion protein gene (PRNP), a site of a common methionine/valine polymorphism, and two distinct conformers of the pathological prion protein. Based on the combination of these molecular determinants, six different sCJD subtypes are recognized, each with distinctive clinical and pathologic phenotypes. We analyzed CSF samples from 127 subjects with definite sCJD to assess the diagnostic value of 14-3-3 protein, total tau protein, phosphorylated₁₈₁ tau, and amyloid beta (Aβ) peptide 1-42, either alone or in combination. While the 14-3-3 assay and tau protein levels were the most sensitive indicators of sCJD, the highest sensitivity, specificity and positive predictive value were obtained when all the above markers were combined. The latter approach also allowed a reliable differential diagnosis with other neurodegenerative dementias.