Low-dose sodium valproate in the treatment of idiopathic generalized epilepsies

Most patients with idiopathic generalized epilepsies (IGEs) have good seizure control when on antiepileptic drugs. To analyze prospectively the response to low-dose sodium valproate (VPA) treatment (<1000 mg/day) together with plasma VPA levels in a cohort of patients with IGE.

Patients with IGE were selected and followed for almost 2 years. In patients on VPA with no seizures in the last year, VPA dose was lowered to <1000 mg/day. Newly diagnosed patients with IGE started treatment on VPA directly on this low dose.

Fifty-four patients were included, with juvenile myoclonic epilepsy (JME) in 23 (42.6%), juvenile absence epilepsy (JAE) in 17 (31.5%), and generalized tonic-clonic seizures only (GTCS only) in 14 (25.9%). VPA at low dose was administered to 38 (70%) patients. Mean plasma VPA level was 44.21 mg/l (18-78; SD 15.18). Seizure relapse during the 2-year follow-up was observed in 8 (21%). A reduction in adverse events was observed (P < 0.048). The only factor related to efficacy of VPA at low dose was syndromic diagnosis. Low-dose VPA controlled 92.9% (13) of patients with GTCS only, 78.3% (18) of those with JME, and 29.5% (5) of those with JAE.

Low-dose VPA was a highly effective treatment for the majority of those with JME and GTCS only. The seizures in JAE tended to be more resistant to treatment, usually requiring higher doses of VPA or polytherapy.