Objective: To assess the relationship between seizure control and gamma-aminobutyric acid (GABA), homocarnosine, and pyrrolidinone levels in the visual cortex of patients with epilepsy taking valproate or lamotrigine. Previous studies suggested that poor seizure control was associated with low GABA and homocarnosine levels.
Methods: In vivo measurements of GABA, homocarnosine, and pyrrolidinone were made in a 14-cm(3) volume of the occipital cortex using (1)H spectroscopy with a 2.1-Tesla MR spectrometer and an 8-cm surface coil. Twenty-six adults (eight men) taking valproate or lamotrigine were recruited; 12 had complex partial seizures (CPS) and 14 had juvenile myoclonic epilepsy (JME).
Results: Median homocarnosine levels were normal for patients with JME and below normal for patients with CPS. Better seizure control was associated with higher homocarnosine levels for both groups. Median GABA was below normal for patients with JME, lower than for patients with CPS. Brain GABA was lowest in patients with JME even when seizure control was excellent. Pyrrolidinone levels were above normal in almost all patients with JME.
Conclusions: Low GABA levels are associated with poor seizure control in patients with CPS, but not in JME. Higher homocarnosine levels are associated with better seizure control in both types of epilepsy.