Cerebrospinal Fluid Neurotransmitters, Pterins, Folates and Amino Acids in Paediatric Onset Epilepsies: A Tertiary Centre Retrospective Cohort Study

<b>Objectives:</b> To investigate the clinical value of cerebrospinal fluid (CSF) testing for biogenic amine, pterins, amino acids, and folates in paediatric onset epilepsies. <b>Methods:</b> Retrospective clinical and biochemical phenotyping of patients with epilepsy who underwent diagnostic CSF measurement of monoamine neurotransmitters, pterins, folates, and amino acids between 2009 and 2022. <b>Results:</b> The studied cohort included 123 patients with epilepsy (mean age at the procedure: 4.54 ± 3.65 years). The diagnostic yield for primary neurotransmitter disorders was 1.68% and zero for inherited amino acid and folate metabolism disorders. Patients with higher seizure frequency showed higher levels of CSF homovanillic acid (HVA) and HVA/5-hydroxyindolacetic acid (5HIAA) ratio. Lower levels of 3-O-methyldopa (3-OMD) were found in patients with co-occurring neurodevelopmental disorders, and lower levels of biopterin, 3-methoxy-4-hydroxyphenylglycol (3-MHPG) and 5-methyltetrahydrofolate (5-MTHF) in those with movement disorders. Significantly lower CSF glutamine levels were found in patients receiving antiseizure medications as polytherapy. Patients with a history of status epilepticus had significantly lower levels of CSF aspartic acid, glycine, leucine, ornithine, and valine, and higher levels of CSF serine. <b>Conclusions:</b> CSF analysis disclosed differences in the concentrations of various metabolites that might be related to the severity of the epilepsy, the presence of comorbid conditions, and medications.