Debate: When does a seizure imply epilepsy?

Abstract

SUMMARYEpilepsy recently has been defined conceptually as a condition of at least one seizure, with an enduring predisposition to have seizures. It is not yet clear how to make this definition operational and practical. A diagnosis of epilepsy has potentially serious consequences for health, psychosocial well-being, and economics, and, therefore, it should be made with a high level of certainty. A definite diagnosis of epilepsy can be made with two unprovoked seizures at least 24 h apart. This method has the benefit of simplicity and consistency with past epidemiologic studies. Nevertheless, certain circumstances suggest a high likelihood of having a second seizure, as evidenced by common clinical practice of considering treatment after a first unprovoked seizure in conjunction with additional risk factors (surrogate markers). One unifying approach is an operational definition of ''definite epilepsy'' after two unprovoked seizures at least 24 h apart. An operational definition of ''probable epilepsy'' can be established with one unprovoked seizure and clinical, electroencephalography (EEG), neuroimaging, genetic, or other information to suggest greater than a 50% chance of having another seizure. ''Possible epilepsy'' operationally would exist with a single unprovoked seizure and insufficient evidence to predict a high likelihood of recurrence. Future clinical and epidemiologic evidence would allow refinements of the operational definitions.

Antiseizure, antidepressant, and antipsychotic medication prescribing in elderly nursing home residents

“…The actual prescribing of these drugs was done by various physicians, and it is not known what criteria were used to make the diagnostic and prescription decisions. With the new classification of epilepsy, a person can be given this diagnosis after a single seizure in the context of a CNS condition known to be associated with recurrent seizures [26]. Thus it is likely that many were treated after a single seizure in the context of a previous stroke, a brain tumor, Alzheimer’s disease or other condition.…”

Treatment of idiopathic generalized epilepsy – a review of the evidence

“…Recently, the International League against Epilepsy (ILAE) defined epilepsy as 'a brain disorder characterized by a predisposition to generate epileptic seizures … and requires the occurrence of at least one epileptic seizure' [3]. Based on this revised definition, it was proposed to stratify patients into those with definite epilepsy (two or more epileptic seizures at least 24 h apart), probable epilepsy (one seizure with > 50% chance of recurrence based on surrogate markers) and possible epilepsy (one seizure with < 50% chance for recurrence) [4].…”

Antiepileptic and Antiepileptogenic Performance of Carisbamate after Head Injury in the Rat: Blind and Randomized Studies

“…Seizures occurring within 5 s of each other were defined as one seizure event. Because all FPI animals were at risk of developing PTE, we diagnosed epilepsy upon their first proven ictal electroclinical event (Beghi et al, 2005;Fisher et al, 2005;Fisher and Leppik, 2008). ECoG seizures were categorized as: 1) grade 1 (G1), if appearing to be limited to a cortical focus; 2) grade 2 (G2), when appearing first in a limited cortical area and then spread to other cortical areas; and 3) grade 3 (G3), if appearing bilateral at their cortical onset.…”