Low brain GABA level is associated with poor seizure control

Abstract

Low gamma‐aminobutyric acid (GABA) concentrations in the cerebrospinal fluid are seen in a variety of epileptic syndromes. Low GABA levels outside of the epileptic focus may facilitate spread of discharges beyond the focus. In vivo measurements of GABA were made by 1 H spectroscopy using a 2.1‐T magnetic resonance imager‐spectrometer and an 8‐cm surface coil to measure a 14‐cm 3 volume in the occipital lobe. Patients with complex partial seizures had lower GABA levels (1.03 mmol/kg of brain; 95% confidence interval [CI], 0.95−1.12; n = 28; p < 0.02) than did subjects without epilepsy (1.18; 95% CI, 1.13−1.24; n = 19). There was a significant association between low GABA levels and recent seizures (correlation coefficient of 0.548, p < 0.01, df of 32). Conversely, patients with well‐controlled seizures had higher brain GABA levels than did patients with recent seizures. Patients with seizures within a day of the measurement had lower GABA levels (0.92 mmol/kg; 95% CI, 0.78−1.06; n = 7) than did patients who were seizure free for 5 years or longer (1.28; 95% CI, 1.09−1.47; n = 4). Poor seizure control is associated with low brain GABA levels.