Intractable epilepsy: definition and neurobiology.

Approximately 20% ef individuals with a diagnosis of epilepsy have seizures that are not adequately controlled by antiepileptic drugs, In some of these, the patients fail to respond because their paroxysmal events are not epileptic; in others, an incorrect treatment plan has been prescribed, either due to misdiagnosis of seizure type or misinformation about appropriate therapy; and in still others, patients are noncompliant and do not take their medications properly. There are, however, a significant group of patients with medically uncontrolled seizures that do not respend to appropriate antiepileptic drug management, and these have been referred to as "medically intractable." Many types of epilepsy can be refractory to pharmacotherapy, but these are usually symptomatic disorders, including certain