A seizure is a group of neurons firing together in an abnormal and uncontrollable fashion, while the term "epilepsy" refers to the tendency to experience recurrent seizures. Seizures can take many different forms and usually involve a loss of consciousness. The 1990s have been an exciting time for the evaluation and treatment of seizures. The widespread use of MRI has become available giving more details of the brain's architecture than was previously available in a noninvasive manner. In addition, eight new medications, in addition to the older traditional medications, have become available as well as an epilepsy treatment device called a vagal nerve stimulator.

This series of articles is not designed to be a complete authoritative guide to epilepsy and seizures (entire books are written on this subject). Rather, it is meant to provide a framework for understanding seizures and epilepsy for the interested non-physician. For the most part, this series focuses more on the epilepsies encountered in adults rather than those epilepsies found in infancy and early childhood as I only treat epilepsy in patients older than thirteen.

New-onset seizures need to be evaluated for potential treatable precipitants. The evaluation usually involves an MRI of the brain (or CT of the brain if emergent imaging is required) to look for mass lesions such as brain tumors, metastatic cancers, or vascular malformations that may have caused the seizure. Blood work should be performed to rule out disorders that may cause seizures such as a high or low glucose, a high or low sodium, a low calcium, a low magnesium, thyroid disorders, among others. Evidence of infection should be checked for with a physical examination and complete blood cell counts. Additional testing is typically ordered depending on the age of the patient and presenting symptoms. Brain wave testing, called the EEG (electroencephalogram), can be helpful in attempting to predict who is more likely to have additional seizures after a first seizure as well as classification of the seizure type. If a phenomenon is recurrent and unclear in nature, then continuous brain wave monitoring may be employed to determine if the behavior is truly a seizure or not. Most importantly, recent patient medication changes must be taken into account to determine if perhaps that may be contributing to the seizure occurrence. Past history of the patient will sometimes reveal diseases, such as severe head injuries, strokes, or Alzheimer's, that may predispose patients to seizures in the future. In increasing numbers, genetics is being identified as a predisposing factor to many disorders including epilepsy.

Although somewhat arbitrary, if no immediate provoking cause is found for the seizure, and more than one seizure occurs, then the patient is said to have epilepsy. I use the term "arbitrary" because many seizures that have a provoking factor, such as sleep deprivation, are still usually considered epilepsy. From a practical standpoint, this has to do with the degree that the immediate provoking cause is sufficient enough to cause the seizure and the degree to which it is found in the typical population. Herpes encephalitis, an infection of the brain itself, causes seizures in a high percentage of persons who have the disease and very few people, if any, have herpes encephalitis without symptoms. Contrast that to being sleep deprived, a situation which most Americans suffer from on a semi-regular occasion and yet very few people will have a seizure associated with sleep deprivation.