Secondary abnormalities of neurotransmitters in infants with neurological disorders

Abstract

Neurotransmitters are essential in young children for differentiation and neuronal growth of the developing nervous system. We aimed to identify possible factors related to secondary neurotransmitter abnormalities in pediatric patients with neurological disorders. We analyzed cerebrospinal fluid (CSF) and biogenic amine metabolites in 56 infants (33 males, 23 females; mean age 5.8mo [SD 4.1mo] range 1d-1y) with neurological disorders whose aetiology was initially unknown. Patients were classified into three clinical phenotypes: epileptic encephalopathy, severe motor impairment, and non-specific manifestations. All patients showed normal results for screening of inborn errors of metabolism. We report clinical, neuroimaging, and follow-up data. Among the patients studied, 10 had low homovanillic acid (HVA) levels and in four patients, 5-hydroxyindoleacetic acid (5-HIAA) was also reduced. Patients with neonatal onset had significantly lower levels of HVA than a comparison group. HVA deficiency was also associated with severe motor impairment and the final diagnosis related to neurodegenerative disorders. 5-HIAA values tended to be decreased in patients with brain cortical atrophy. The possibility of treating patients with L-Dopa and 5-hydroxytryptophan, in order to improve their neurological function and maturation, may be considered.Brain neurotransmission is essential in young children, not only for interneuronal communication but also for differentiation, neuronal growth, and shaping and wiring of the nervous system. 1 Biogenic amines are the most representative group among brain neurotransmitters 2 and are composed of catecholamines (dopamine and norepinephrine) and serotonin. Within the central nervous system, the final metabolite for dopamine is homovanillic acid (HVA) and for serotonin, 5-hydroxyindoleacetic acid (HIAA). These metabolites can be measured in the cerebrospinal fluid (CSF). Low concentrations of biogenic amine metabolites in the CSF are mainly due to defects in their biosynthetic and catabolic pathways. Deficiencies of tyrosine hydroxylase, aromatic L-amino acid decarboxylase, guanosine triphosphate cyclohydrolase (GTPCH), and sepiapterin reductase, 3 (the last two enzymes contributing to the formation of tetrahydrobiopterin [BH4]), cause the main paediatric neurotransmitter diseases.Little is known about secondary causes of low CSF biogenic amine metabolites, and, to our knowledge, no study focusing on how diverse neurological disorders in infants could affect brain biogenic amines production has been described until now. There are a few studies that have looked at secondary reduction of HVA. It has been reported that epilepsy, 4,5 rapidonset dystonia-parkinsonism, 6 Huntington's disease, 7 and depression and dementia 8,9,10 are among those disorders characterized by secondary reduction of HVA. However, the results found in these studies are often contradictory and not specific to young children. Moreover, no study concerning possible factors that could be related to these secondary abnormalit...

Analysis of synaptic proteins in the cerebrospinal fluid as a new tool in the study of inborn errors of neurotransmission

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Clinical Utility of Monoamine Neurotransmitter Metabolite Analysis in Cerebrospinal Fluid

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Neurotransmitter abnormalities and response to supplementation in SPG11

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