Application of recent international epidemiological guidelines to a prospective study of the incidence of first seizures, newly-diagnosed epilepsy and seizure mimics in a defined geographic region in Ireland

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Maloney, Eimer M.
Chaila, Elijah
O'Reilly. Éilis J.
Costello, Daniel J.
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Karger Publishers
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Studies adherent to international guidelines and epilepsy classification are needed to accurately record the incidence of isolated seizures, epilepsy and seizure-mimics within a population. Because the diagnosis of epilepsy is largely made through clinical assessment by experienced physicians, seizures and epilepsy are susceptible to misdiagnosis. Previous epidemiological studies in epilepsy have not captured â seizure mimicsâ . We therefore sought to quantify the incidence of isolated seizures, epilepsy and seizure-mimics using the International League Against Epilepsy (ILAE) classification system. In this study multiple overlapping methods of case ascertainment were applied to a defined geographic region from January 1 to March 31, 2017 to identify all patients presenting with first seizures (provoked and unprovoked), new diagnoses of epilepsy and seizure mimics. Over a 3 month period, from a population of 542,869 adults and children, 442 potential presentations were identified, and 283 met the inclusion criteria. Radiology databases were the source of the largest number of individual cases (n = 153, 54%), while electroencephalogram (EEG) databases were the source of the highest number of unique-to-source cases (those not identified elsewhere, n = 60, 21%). No single case was picked up in every method of ascertainment. Among the 283 included presentations, 38 (13%) were classed as first provoked seizures, 27 (10%) as first unprovoked seizures, 95 (34%) as new diagnosis of epilepsy and 113 (40%) as seizure mimics. Ten (3%) presentations were indeterminate. We present and apply a rigorous study protocol for investigation of the incidence of first seizures, new diagnosis of epilepsy and seizure mimics in a geographically defined region which is adherent to recently published international guidelines for epidemiologic studies and epilepsy classification. We highlight the challenges in making a diagnosis of new-onset epilepsy in patients presenting with a first seizure using the current ILAE definition of epilepsy, when epilepsy can be diagnosed in situations where the treating physician anticipates the risk of further seizures exceeds 60%.
Epilepsy , Incidence , Epidemiological protocol
Maloney, E. M., Chaila, E., O’Reilly, É. J. and Costello, D. J. (2019) 'Application of Recent International Epidemiological Guidelines to a Prospective Study of the Incidence of First Seizures, Newly-Diagnosed Epilepsy and Seizure Mimics in a Defined Geographic Region in Ireland', Neuroepidemiology, 53(3-4), pp. 225-236. doi: 10.1159/000502009
© 2019 S. Karger AG, Basel. This is the peer-reviewed but unedited manuscript version of the following article: Neuroepidemiology 2019;53:225–236, doi: 10.1159/000502009 . The final, published version is available at