Topiramate Effectiveness as Add-on Therapy in Bulgarian Patients with Drug-resistant Epilepsy

Abstract

Introduction: There are no reliable prospective studies on the effectiveness of topiramate in Bulgarian adult patients with drug-resistant epilepsy. Aim: The aim of the study was to conduct an open, prospective study on various aspects of topiramate (TPM) effectiveness in Bulgarian patients with drug-resistant epilepsy. Patients and methods: The study included patients with epilepsy who attended the Clinic of Neurology at the University Hospital in Plovdiv, Bulgaria. Patients completed diaries for seizure frequency, seizure severity, and adverse events. There were regular documented visits at 3 or 6 months during the first year of TPM treatment and at 6 months afterwards, with a dynamic assessment of seizure frequency, severity, adverse events, and EEG recordings. Results: TPM was used as an add-on treatment in 120 patients (69 males, mean age 37 years). There was a relatively mild and stable dynamic improvement of seizure severity, a satisfactory seizure frequency reduction in 37% of participants, a stable mean seizure frequency reduction (47%) from month 6 to month 24 of treatment and a stable responder rate (48-51%) during the same period. New seizure types (focal with impaired awareness with/without evolution to bilateral tonic-clonic seizures) occurred in 5 patients. There were adverse events (dizziness/vertigo, irritability, speech disturbances, memory impairment, concentration problems, tremor, loss of appetite and weight, weakness, numbness, bradypsychia, confusion, visual hallucinations, sleepiness, insomnia, headache, itching, unstable gait, nausea, and vomiting) in 20% of patients. Conclusions: TPM treatment is associated with low and stable improvement of seizure severity, good and stable improvement of seizure frequency, possible worsening of seizure control and appearance of new seizure types, good safety and tolerability.