Effects of vigabatrin on brain GABA+/Cr signals in focus‐distant and focus‐near brain regions monitored by 1 H‐NMR spectroscopy

The new antiepileptic drug vigabatrin (VGB) increases gamma‐aminobutyric acid (GABA) in the brain. We compared GABA+/Cr signals measured focus‐near and focus‐distant and correlated it with the degree of response to VGB. Brain GABA+/Cr signals were measured in 17 epileptic patients in structurally normal appearing tissue by nuclear proton magnetic resonance ( 1 H‐NMR) spectroscopy using a special editing sequence for GABA. In 11 patients the measurements were done in brain areas distant to focus and in six near to focus. Full‐responders (seizure reduction of ≥50% at the end of the treatment phase) and partial‐responders (seizure reduction of ≥50% at the end of the first month of treatment but ≤50% at end of treatment) had lower GABA+/Cr signals in the hemisphere with the epileptogenic focus and increases of the GABA+/Cr signals with VGB. Non‐responders (seizure reduction of ≤50%) had no side difference in the GABA+/Cr signals before treatment and no increase during treatment. These observations were made in structurally normal appearing tissue near to the focus and distant to the focus. A side difference in brain GABA+/Cr signal between the epileptogenic and non‐epileptogenic hemisphere before VGB treatment correlates with an improved seizure control under VGB treatment regardless whether the measurement is done focus‐near or focus‐distant.