A type of drug that is used to prevent or treat seizures or convulsions by controlling abnormal electrical activity in the brain. Anticonvulsants are used to treat epilepsy and other seizure disorders. They are also used to treat medical conditions, such as bipolar disorder, nerve pain, migraine headaches, fibromyalgia, and restless leg syndrome. There are many different types of anticonvulsants. Also called anti-seizure medication and antiepileptic.