Long-term EEG monitoring: a clinical approach to electrophysiology.

Long-term electroencephalographic monitoring (LTM) is the capability of recording the EEG over long periods of time and not a specific duration. Prolonged EEG recording is used primarily for epilepsy monitoring, but LTM is also used in the intensive care unit, the operating room, and in the emergency department. The purpose of LTM is to expand the limited time sampling associated with shorter "routine" EEG recording. Audiovisual monitoring may also be used in conjunction with LTM to evaluate simultaneously a specific clinical behavior that may or may not be associated with EEG alteration. This is typically performed in a hospital setting for safety and ancillary testing purposes. LTM is used most frequently in the diagnosis and management of seizures and "spells," but has also gained wider application in the evaluation of sleep disorders, cerebrovascular disease, psychiatric conditions, and movement disorders. Computer-assisted LTM systems that process, analyze, compress, and store data digitally have become widely available in clinical practice both in the hospital as well as outside the hospital when the patient is ambulatory.