Decreased homovanillic acid concentrations in cerebrospinal fluid in children without a known defect in dopamine metabolism.

Homovanillic acid (HVA) is a metabolite of dopamine, reflecting central dopamine metabolism, primarily situated in the striatum. Low HVA concentrations in the cerebrospinal fluid (CSF) may indicate metabolic deficiencies in the pathways of the biosynthesis or catabolism of dopamine. In this retrospective study, we investigated the clinical presentation of patients whose HVA concentration in the CSF had been determined routinely after spinal taps for a variety of clinical reasons. A decrease of HVA concentration in the CSF, due to a defect in the biosynthesis or reuptake of dopamine, is expected to cause extrapyramidal features. However, we found a remarkable variability in the clinical symptoms. Similarly, a decreased HVA concentration in the CSF failed to coincide with specific abnormalities at neuroimaging. In view of the diversity of the clinical presentation and in the absence of specific enzyme deficiencies, a decrease of HVA may be due to dysfunction of dopamine neurons, not resulting in specific extrapyramidal symptoms. Thus, with the exception of diseases associated with a specific enzyme deficiency in the metabolic pathways involving dopamine, a decrease of HVA concentration in the CSF is mainly a secondary or epiphenomenon in a variety of clinical conditions.