Cerebrospinal fluid pterins, pterin-dependent neurotransmitters, and mortality in pediatric cerebral malaria.

Abstract

BACKGROUND: Cerebral malaria (CM) pathogenesis remains incompletely understood. Having shown low systemic levels of tetrahydrobiopterin (BH4), an enzymatic cofactor for neurotransmitter synthesis, we hypothesized that BH4 and BH4-dependent neurotransmitters would likewise be low in cerebrospinal fluid (CSF) in CM. METHODS: We prospectively enrolled Tanzanian children with CM and children with non-malaria central nervous system conditions (NMC). We measured CSF levels of BH4, neopterin, and BH4-dependent neurotransmitter metabolites, 3-O-methyldopa, homovanillic acid, and 5-hydroxyindoleacetate, and derived age-adjusted z-scores using published reference ranges. RESULTS: CSF BH4 was elevated in CM (n=49) compared to NMC (n=51) [z-score 0.75 vs. -0.08 (p<0.001)]. Neopterin was increased in CM [z-score 4.05 vs. 0.09 (p<0.001)], and a cut-off at the upper limit of normal (60 nmol/L) was 100% sensitive for CM. Neurotransmitter metabolite levels were overall preserved. A higher CSF BH4:BH2 ratio was associated with increased odds of survival (OR 2.94 [1.03-8.33]; p=0.043). CONCLUSION: Despite low systemic BH4, CSF BH4 was elevated and associated with increased odds of survival in CM. Coma in malaria is not explained by deficiency of BH4-dependent neurotransmitters. Elevated CSF neopterin was 100% sensitive for CM diagnosis, and warrants further assessment of its clinical utility for ruling out CM in malaria-endemic areas.