Effects of vigabatrin intake on brain GABA activity as monitored by spectrally edited magnetic resonance spectroscopy and positron emission tomography

A deficit in gamma-aminobutyric acid (GABA) levels in the brain or the cere brospinal fluid (CSP) is found in many epilepsy patients. Frequency and sev erity of seizures may be reduced by treatment with GABA increasing medicame nts as e.g. vigabatrin, an irreversible inhibitor of GABA-transaminase. For a better understanding of the associated effects, healthy volunteers were examined with magnetic resonance spectroscopy (MRS) and positron emission t omography (PET) before and after intake of different doses of vigabatrin. F or the MRS examinations, a dedicated localized spectral editing method was developed to determine GABA levels. The C-11-flumazenil (FMZ)-PET protocol allowed determination of GABA-A receptor binding. The results show a clear and dose-dependent increase in the brain GABA levels after the medication p eriod as compared to the baseline values. The GABA-A receptor binding, on t he other hand, did not change significantly. (C) 1999 Elsevier Science Inc.