An audit of the use of vigabatrin in the treatment of medically refractory epilepsy at a presurgical unit

In this retrospective study we examined the use of vigabatrin (VGB) in the presurgical evaluation unit at the Department of Epileptology and Electroencephalography of the University Hospital of Zürich. Vigabatrin had been used in 125 out of 750 difficult-to-treat patients with epilepsy. They received VGB primarily as add-on therapy because of drug-resistance to first-line antiepileptic drugs (AEDs). With a few exceptions, most patients suffered from frequent partial seizures with and without secondary generalization. In 22.4% of patients VGB showed a beneficial long-term effect with > 50% seizure reduction and an additional 5.5% of patients became seizure-free without epilepsy surgery. Most frequent reasons for discontinuation were “no efficacy” and “loss of efficacy” after short-turn improvement, followed by adverse events. Adverse events most frequently observed were weight gain (5%); tiredness (3%); and “confusion, depersonalization, and psychosis” (2%). The year-by-year retention rate for VGB for the 125 patients was 55% after 1 year and 22% after 5 years. These long-term retention rates are lower than those observed in controlled clinical trials. We conclude that the year-by-year retention rate represents a more realistic and most probably the most useful measure for the value of VGB in the long-term management of a difficult-to-treat epilepsy population.

Key words: Vigabatrin, Long-term-efficacy, Difficult-to-treat epilepsy, Discontinuation of treatment, Year-by-year retention rates

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