What is drug resistant epilepsy When epilepsy surgery should be considered

Fifty million people in the world have epilepsy, and there are between 16 and 51 cases of new-onset epilepsy per 100,000 people every year (1), and close to one-third of these cases finally become drug resistant (2). Patients with drug-resistant epilepsy have increased risks of premature death (3), injuries, psychosocial dysfunction, and a reduced quality of life (4). Diverse criteria have been used to define drug resistance by different researchers, making it difficult or even impossible to compare the results across different studies. The last ILAE category defines drug-resistant epilepsy as failure of adequate trials of two (or more) tolerated, appropriately chosen and used AED schedules (whether as monotherapies or in combination) to achieve sustained seizure freedom. Most patients with drug-resistant epilepsy have a long and complex treatment history. Due to insufficient information, treatments labelled as failures might not have truly failed because they have not been tried adequately due to, for instance, allergic reaction at low dose or early withdrawal for reasons unrelated to treatment (5). Thus, the definition may help clinicians and patients to be alerted to the essential information that needs to be collected during routine consultations. Patients should also be educated on the avoidance of triggers of seizure relapse, particularly non-compliance and lifestyle factors such as sleep deprivation, excessive alcohol intake, an irregular sleep–wake cycle and drug abuse (6). Selected patients with drug-resistant epilepsy may benefit from a non-pharmacological intervention, such as epilepsy surgery (7). Given that these interventions are invasive, costly, and not without risk (8), confirming the diagnosis of drug resistance is generally considered a prerequisite. There is no consensus definition of drug resistance for the purpose of selecting patients for epilepsy surgery. Diverse criteria used by different groups might have contributed to the disparity in post-surgery outcome reported. By providing the minimum core criteria, the proposed ILAE definition represents a common platform that can be adapted specifically for the purpose of selecting patients for non-drug therapies. This will avoid delay in evaluating patients for these therapeutic options and facilitate meaningful comparison of effectiveness reported in different studies. References:1. Banerjee PN, Filippi D, Hauser WA. The descriptive epidemiology of epilepsy — a review. Epilepsy Res 2009; 85:31-45 2. Picot MC, Baldy-Moulinier M, Daurès JP, Dujols P, Crespel A. The prevalence of epilepsy and pharmacoresistant epilepsy in adults: a population-based study in a Western European country. Epilepsia 2008; 49:1230-8.3. Mohanraj R, Norrie J, Stephen LJ, Kelly K, Hitiris N, Brodie MJ. Mortality in adults with newly diagnosed and chronic epilepsy: a retrospective comparative study. Lancet Neurol 2006; 5:481-7. 4. Lawn ND, Bamlet WR, Radhakrishnan K, O’Brien PC, So EL. Injuries due to seizures in persons with epilepsy: a populationbased study. Neurology 2004; 63:1565-70 5. Mohanraj R, Brodie M, Diagnosing refractory epilepsy: response to sequential treatment schedules, Eur J Neurol, 2006;13:277–82 6. Perucca E, Pharmacoresistance in epilepsy: how should it be defined CNS Drugs, 1998;10:171–9. 7. Engel Jr J, Wiebe S, French J, et al., Practice parameter: temporal lobe and localized neocortical resections for epilepsy: report of the Quality Standards Subcommittee of the American Academy of Neurology, in association with the American Epilepsy Society and the American Association of Neurological Surgeons, Neurology, 2003;60:538–47. 8. Go C, Snead III O, Pharmacologically intractable epilepsy in children: diagnosis and preoperative evaluation, Neurosurg Focus, 2008;25: E2