Value of lumbar puncture in the diagnosis of genetic metabolic encephalopathies

Application of metabolomics in diagnostics and differentiation of meningitis: A narrative review with a critical approach to the literature

Due to its high mortality rate associated with various life-threatening sequelae, meningitis poses a vital problem in contemporary medicine. Numerous algorithms, many of which were derived with the aid of artificial intelligence, were brought up in a strive for perfection in predicting the status of sepsis-related survival or exacerbation. This review aims to provide key insights on the contextual utilization of metabolomics. The aim of this the metabolomic approach set of methods can be used to investigate both bacterial and host metabolite sets from both the host and its microbes in several types of specimens - even in one's breath, mainly with use of two methods - Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR). Metabolomics, and has been used to elucidate the mechanisms underlying disease development and metabolic identification changes in a wide range of metabolite contents, leading to improved methods of diagnosis, treatment, and prognosis of meningitis. Mass spectrometry (MS) and Nuclear Magnetic Resonance (NMR) are the main analytical platforms used in metabolomics. Its high sensitivity accounts for the usefulness of metabolomics in studies into meningitis, its sequelae, and concomitant comorbidities. Metabolomics approaches are a double-edged sword, due to not only their flexibility, but also - high complexity, as even minor changes in the multi-step methods can have a massive impact on the results. Information on the differential diagnosis of meningitis act as a background in presenting the merits and drawbacks of the use of metabolomics in context of meningeal infections.

Seizures with decreased levels of pyridoxal phosphate in cerebrospinal fluid

Although pyridoxine-dependent seizures have been reported for decades, pyridoxamine phosphate oxidase deficiency has only been recently described. Pyridoxamine phosphate oxidase (PNPO) is one of a series of enzymes involved in converting pyridoxine to pyridoxal 5'-phosphate, the biologically active form of pyridoxine. PNPO deficiency is associated with decreased levels of pyridoxal 5'-phosphate in CSF, as well as epilepsy. We describe four children up to 16 years of age with intractable seizures who all had low cerebrospinal fluid (CSF) levels of pyridoxal 5'-phosphate. Only one of the four children possessed a genetic alteration, a novel homozygous variant in exon one of the PNPO gene. Three of four, however, showed at least some clinical improvement with pyridoxal 5'-phosphate supplementation. Low CSF pyridoxal 5'-phosphate levels, although considered a diagnostic biomarker for PNPO deficiency, lack specificity and may result from multiple other causes. Genetic testing and CSF evaluation, along with clinical response are all necessary for accurate diagnosis.

Biochemical parameters to assess choroid plexus dysfunction in Kearns-Sayre syndrome patients

Our aim was to assess biochemical parameters to detect choroid plexus dysfunction in Kearns-Sayre syndrome (KSS) patients. We studied CSF from 7 patients with KSS including total proteins, 5-methyltetrahydrofolate, homovanillic acid (HVA) and Selenium (Se) concentrations. High Se values, increased HVA and total protein concentrations and decreased 5-MTHF values were observed in all cases. This pattern seems very specific to KSS since it was only detected in 7 patients out of 1850 CSF samples analysed, and may represent a good biochemical model for evaluating choroid plexus dysfunction. The accumulated Se in CSF might have deleterious consequences such as toxicity effects.

Pyridoxal 5'-phosphate values in cerebrospinal fluid: reference values and diagnosis of PNPO deficiency in paediatric patients

Our aim was to establish reference values for cerebrospinal fluid (CSF) pyridoxal 5'-phosphate (PLP) in a paediatric population for the diagnosis of pyridox(am)ine 5'-phosphate oxidase (PNPO) deficiency. For reference values, CSF samples from 113 paediatric controls (age range: 1 day-18 years) from Barcelona and London were analysed. Cerebrospinal fluid PLP and biogenic amine concentrations were analysed by HPLC with fluorescence and electrochemical detection. Pyridoxal 5'-phosphate concentrations in 4 patients with PNPO deficiency were determined. A negative correlation between CSF PLP values and age of controls was observed in both populations (r=-0.503; p<0.0001 and r=-0.542; p=0.002). Reference values were stratified into 4 (Barcelona) and 3 age groups (London). For the newborn period, CSF PLP reference intervals were 32-78 and 44-89 nmol/L for the Barcelona and London centers, respectively). No correlation was observed in the different age groups between PLP values and biogenic amines metabolites. PLP values in neonates with PNPO deficiency were clearly decreased (PLP=3.6, 12.0, 14.0 and 18.0 nmol/L) compared with our reference ranges. In conclusion, reference values for CSF PLP should be stratified according to age. No association was observed between PLP values and biogenic amines metabolites. In our 4 cases with PNPO deficiency, CSF PLP values were clearly below the reference values.

Applying advances in neurogenetics to medical practice

The investigation of rare neurogenetic diseases is an example of how a translational science approach may lead to the delineation of complex genetic and biochemical pathways. Thisprocess comprises several intellectual stages. The first step involves the astute identification and clinical description of the unique phenotype, which may lead to obvious pathways or may reveal novel or unexpected mechanisms. As similar patients are identified, the establishment of databases detailing the clinical phenotype may serve to provide clues as to the genetic and biochemical characterization, and identification of the genetic mutation based on patient samples and animal or cellular models. Lastly, attempts to develop and apply therapies based on what has been learned about the biochemical and molecular bases of the disease enables intervention on the individual patient level. Several stages of discovery may overlap or be investigated simultaneously. As examples, this review discusses how this process of investigation has enabled progress in the delineation of several genetic and neurogenetic disorders, including Progeria syndrome, neurodegenerative diseases, muscular dystrophy, Rett syndrome and neurotransmitter disorders. This review attempts to summarize the transition from the bedside-to-bench-to-bedside as a model of bringing such discoveries into the clinical arena, and in doing so addresses the issues that may enhance, or complicate, such a path of discovery, as well as the impact such advances in genetics and genomics may have on the practice of clinical medicine and the role of the physician.

Cerebrospinal fluid analysis in the diagnosis of treatable inherited disorders of neurotransmitter metabolism

The inherited disorders affecting dopamine and serotonin (5-hydroxytryptamine) metabolism are being recognized as treatable causes of neurological problems that affect infants, children and adults. Diagnosis of these conditions in many cases requires that neurotransmitter metabolites, and the cofactors required for their synthesis, be measured in cerebrospinal fluid (CSF). This review will concentrate on the inherited disorders that affect dopamine and serotonin biosynthesis and an overview will be given of the metabolism of these two neurotransmitters. The metabolite pattern found in each known defect is also given. Emphasis is put on the need to collect and handle CSF in the appropriate manner if meaningful results from neurotransmitter metabolite measurements are to be obtained. The clinical phenotypes that might be associated with neurotransmitter deficiency are described, and finally, speculation will be provided as to the metabolite patterns that might occur in the CSF in disorders that are yet to be discovered.

Utilidad del análisis del líquido cefalorraquídeo para el estudio de las deficiencias del metabolismo de neurotransmisores y pterinas y del transporte de glucosa y folato a través de la barrera hematoencefálica

BACKGROUND AND OBJECTIVE

In the last few years, it has been described inborn errors of neurotransmitter and pterin metabolism and defects in folate and glucose transport across blood brain barrier. All these defects are classified as rare diseases and needs cerebrospinal fluid (CSF) sample analysis for diagnosis. Our aim was to evaluate the results of the application of a CSF analysis protocol in a pediatric population from Spain and Portugal presenting with neurological disorders of unknown origin.

PATIENTS AND METHOD

We studied CSF samples from and 283 patients with neurological disorders of unknown origin and 127 controls. Neurotransmitters were analysed by HPLC with electrochemical detection, and pterins and 5-methyltetrahydrofolate were determined by HPLC with fluorescence detection.

RESULTS

We diagnosed 3 patients with tyrosine hidroxylase deficiency, 2 with dopa responsive dystonia, 14 with GTP-ciclohydrolase deficiency, 2 with glucose transport deficiency and 43 with cerebral folate deficiency.

CONCLUSIONS

This study allowed us to diagnose new patients, and more importantly, the establishment in all of them of a pharmacological or nutritional treatment. The most frequent defect found was CSF 5-methyltetrahydrofolate deficiency, which was present in different groups of patients.

HPLC with electrochemical and fluorescence detection procedures for the diagnosis of inborn errors of biogenic amines and pterins

The analysis of biogenic amines (BA) and pterins in cerebrospinal fluid (CSF) is essential for the early diagnosis of neurotransmission defects in the paediatric age. Our aim was to standardize previously reported HPLC procedures for the analysis of BA and pterins in CSF and to establish reference values for a paediatric population. Samples from 127 subjects (age range 11 days to 16 years; average 3.8) were analyzed by HPLC with electrochemical and fluorescence detection. Both BA (homovanilic and 5-hydroxyindoleacetic acid) and pterins (neopterin and biopterin) concentrations in CSF showed a negative correlation with age. This finding led us to stratify reference values into six groups according to age. In conclusion, analysis of BA and pterins in CSF by HPLC procedures is a useful set of tools for the diagnosis of inborn errors of metabolism of these compounds. The establishment of reference intervals may be difficult, since there is a strong correlation between BA concentrations and the age of controls and, as a result, a large number of CSF samples from control populations would be necessary for this purpose.

Folinic acid-responsive seizures presenting as breakthrough seizures in a 3-month-old boy

Neonatal seizures associated with white-matter changes on neuroimaging suggest an etiology of hypoxic-ischemic encephalopathy. Metabolic and idiopathic etiologies are also considerations but are less likely. Despite the fact that two disorders associated with neonatal seizures are diagnosed by cerebrospinal fluid neurotransmitter analysis, such an analysis is not standard in the work-up for idiopathic neonatal seizures. We describe an infant who had a prolonged delivery, seizures on the first day of life, and white-matter changes on neuroimaging. A progressive seizure disorder that was refractory to standard antiepilepsy medications developed at 2 months of age. Analysis of cerebrospinal fluid neurotransmitters at that time demonstrated a pattern consistent with folinic acid-responsive seizures. Seizures ceased 24 hours after starting folinic acid. Serial neuroimaging, electroencephalograms, and metabolic changes from this patient are presented. This case illustrates the importance of cerebrospinal fluid neurotransmitter analysis as part of the work-up for idiopathic neonatal seizures.

Dopa-responsive Dystonia in Children

Treatment of dopa-responsive dystonia is one of the more satisfying experiences in clinical neurology. The response to treatment with levodopa is usually dramatic and complete with no long-term complications. Carbidopa/levodopa is the mainstay in treating dopa-responsive dystonia. There is some experience using anticholinergic agents, but they are more likely to cause side effects and do not treat the underlying biochemical abnormality. Dopa-responsive dystonia caused by guanosine triphosphate cyclohydrolase I deficiency typically presents with dystonia in the lower extremities in the first decade of life. However, the presenting symptoms can vary. Thus, it is this author's recommendation that any child with dystonia receive a trial of carbidopa/levodopa.