Decreased homovanillic acid and 5‐hydroxyindoleacetic acid levels in the cerebrospinal fluid of patients with Dravet syndrome with parkinsonism

Dravet syndrome (DS) is an early onset, developmental, and epileptic encephalopathy characterized by drug-resistant seizures and multiple comorbidities. It has been reported that in adulthood, it may be accompanied by parkinsonism, but the pathogenesis of this condition remains unclear. We performed dopamine transporter single-photon emission computed tomography (DAT SPECT) and measured monoamine metabolite levels in the cerebrospinal fluid (CSF) in two adult patients with DS who developed parkinsonism around the age of 30 years. DAT SPECT showed no abnormalities in either patient, whereas CSF tests revealed significant decreases in the levels of homovanillic and 5-hydroxyindoleacetic acids. One patient with severe symptoms was treated with levodopa–carbidopa, which improved parkinsonism manifestations. The other patient initiated treatment with a low dose and has been continuing the treatment without any reported side effects. In conclusion, CSF testing can detect a decrease in dopamine synthesis and may be useful in monitoring the efficacy of levodopa treatment in patients with DS and parkinsonism.
Plain Language Summary: Dravet syndrome (DS) is an early onset, developmental, and epileptic encephalopathy. DS can lead to the development of parkinsonism in adulthood, a clinical syndrome characterized by tremor, slowed movements, and rigidity. Although parkinsonism is a significant issue for patients, its underlying pathology has not yet been elucidated. In this study, we confirmed that the levels of monoamine metabolites in the CSF were low in two patients, potentially shedding light on the pathology involved.