The most difficult, and most important, differential diagnosis for which VEM is used is the distinction between epileptic seizures and psychogenic nonepileptic seizures. In most of these situations, however, the results of VEM merely confirm the clinical impression derived from historical and other information, and are not diagnostic in themselves. 14 Many other nonepileptic disorders can be recognized readily by clinical examination during the habitual event, by review of video recordings, or both. Myoclonic jerks may also have no EEG correlates but usually can be diagnosed on the basis of characteristic motor signs. 12 Consequently, seizures without impaired consciousness are diagnosed most often by characteristic behavioral features and, at times, elevated serum prolactin levels, 13 rather than by the occurrence of ictal EEG discharges. In this case, a diagnosis usually is reached with reasonable confidence based on features of the ictal behavior in association with other clinical and laboratory information.įocal seizures without amnesia or alteration of consciousness (traditionally called simple partial seizures) usually have no EEG correlates that can be recorded with extracranial electrodes. Often, however, the events in question occur without obvious EEG or other electrophysiologic changes. 11 A definitive diagnosis is made easily when habitual events are shown to consist of clinical behaviors characteristic of epilepsy and are associated with well-defined ictal EEG discharges, or when other etiologies can be clearly demonstrated (e.g., cardiac arrhythmias or sleep disturbances).
VEM is often used as the ultimate test in the differential diagnosis between epilepsy and other disorders associated with intermittent or paroxysmal disturbances that resemble epileptic seizures. Its use should be limited to diagnostic problems that cannot be resolved easily in the routine EEG laboratory. VEM can be expensive and labor-intensive, but it is cost-effective in many circumstances. stern, Jerome Engel Jr, in Aminoff's Electrodiagnosis in Clinical Neurology (Sixth Edition), 2012 Indications