Imaging of serotonin mechanisms in epilepsy

Abstract

Advances in positron emission tomography (PET) techniques have allowed the measurement and imaging of neurotransmitter synthesis, transport, and receptor binding to be performed in vivo. With regard to epileptic disorders, imaging of neurotransmitter systems not only assists in the identification of epileptic foci for surgical treatment, but also provides insights into the basic mechanisms of human epilepsy. Recent investigative interest in epilepsy has focused on PET imaging of tryptophan metabolism, via the serotonin and kynurenine pathways, as well as on imaging of serotonin receptors. This review summarizes advances in PET imaging and how these techniques can be applied clinically for epilepsy treatment.

FIGURE 1

Scalp ictal EEG (A) versus [¹⁸F]fluorodeoxyglucose (FDG) (B, C) and AMT (D, E) PET scans in a 1-year-old boy with tuberous sclerosis complex and uncontrolled focal seizures. Scalp ictal EEG recording (A) showed sustained, irregular rhythmic slow-wave activity in the left parietal-central region, involving midline electrodes (with the highest amplitude at C3–P3). Interictal FDG PET scan (B, C) showed multifocal nodular hypometabolic regions, including the left inferior and medial parietal regions (designated by arrowheads). Based on the ictal EEG and FDG PET findings, possible epileptogenicity in the left medial parietal region could not be ruled out. A single area of increased AMT uptake (D, E) is detected in the left inferior lateral parietal region (arrow).