Moderate hyperhomocysteinemia in patients treated for epilepsy

Homocystein (Hcy) is regarded as a neuroexcitatory substance, which is therefore used as an epileptogenic agent in experimental epileptology. Experiments "in vivo" as well as "in vitro" revealed its relation to NMDA glutamate receptors, and its potential neurotoxicity. From the clinical aspect, hyperhomocysteinemia (HHcy), mostly as a marker of the risk factor in the vascular damage, was often studied in patients treated with antiepileptic drugs (AE). However, the neuroexcitatory influence of mild HHcy (up to 30 micromol/l) was rarely discussed. Out of a group of 123 adult patients on long-term conventional AE we analyzed 8 patients (7 men and one woman) with moderate to severe HHcy (30.7-109.0 micromol/l) retrospectively and 2-5 years after HHcy normalization. All of them suffered from partial and/or secondary generalized seizures accompanied by neuropsychological impairment depending on the aetiology of the disease. The patients were characterized by a concurrence of several factors: (1) All of them received conventional AEs inducing the cytochrome P 450 at the time HHcy was diagnosed. (2) Molecular-genetic tests showed enzymopathic impairment (methylentetrahydrofolate reductase-MTHFR mutation of the gene C677 T) also in all eight, homozygous in 7 cases and heterozygous in 1 case. (3) All patients were found to have a vitamin deficit or marginal values of at least one of the vitamins under study, especially folate and/or vitamin B6 and 812. With reference to clinical and EEG features, the potential neuroexcitatory influence of Hcy is discussed taking into account its effect on pathogenetic factors.