The epidemiology and treatment of chronic and refractory epilepsy. 
In developed countries, the incidence of epilepsy is 50-100 cases per 100,000 population per year and the prevalence is approximately 5 to 8 cases per 1,000 population.  Epilepsy is by far the most prevalent serious neurologic condition.  Mortality rates in epilepsy are two to four times those found in matched nonepileptic populations.  The prognosis of epilepsy can be classified into at least four categories, with chronic and refractory cases comprising about 40% of all cases.  A detailed approach to the management of chronic epilepsy cases is recommended.  Approximately 20% of patients cannot achieve seizure control with existing agents and new antiepileptic drugs are required for these patients.