Absence seizure: (also know as "dialeptic seizure" or "petit mal seizure") a seizure that causes a brief loss of awareness. During an absence seizure, the patient stops any activity and stares blankly. Rarely, there may be some blinking.
Anticonvulsant: an antiepileptic drug used to control both convulsive and nonconvulsive seizures.
Epilepsy is a general term for the tendency to have seizures. Epilepsy is usually diagnosed only after a person has had more than one seizure.
When identifiable, the causes of epilepsy usually involve some form of injury to the brain. For most people, though, epilepsy's causes aren't known.
Atonic seizure: a seizure that causes a sudden loss of muscle tone, particularly in the arms and legs, and often causes the patient to fall.
Aura: a warning or initial symptom at the beginning of a seizure, experienced by the patient, but not visible to observers. Auras may progress to become focal or even generalized seizures, or they may exist alone.
Clonic seizure: repetitive, rhythmic jerks that involve all or part of the body.
Complex partial seizure: a seizure that includes impairment of awareness, for example, patients seem to be "out of it" or "staring into space." Unintentional movements or other movements are frequently a part of the seizure.
Corpus callosum: a band of nerve fibers located deep in the brain that connects the two halves (hemispheres) of the brain. The corpus callosum helps the hemispheres share information.
Corpus callosotomy: an operation that cuts the corpus callosum and interrupts the spread of seizures from one hemisphere of the brain to the other. Callosotomies may be complete, or may involve only a portion of the corpus callosum. Although seizures generally do not completely stop after this procedure, they usually become less severe.
EEG-video monitoring: Continuous simultaneous recording of brainwaves and video observation of the behavior accompanying the EEG. This technique, carried out at comprehensive epilepsy centers, is employed to diagnose epilepsy and localize the seizure focus. The results are useful to determine therapy -- medical or surgical.
Epilepsy: a chronic medical condition marked by recurrent epileptic seizures. Patients may have single seizures as a result of fever, drug withdrawal, or trauma, for example, but are not labeled as having epilepsy if seizures do not recur.
Epileptogenic zone: the region of the brain responsible for the abnormal electrical signals that cause seizures.
Electrode: a conductive disk (usually metal) attached to the scalp which conveys the electrical activity of the brain through a wire to an EEG machine. During an electroencephalogram, typically around 20 electrodes are temporarily pasted to the scalp.