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P71 The incidence of first seizures, new diagnosis of epilepsy, and seizure mimics in a defined geographic region in ireland
  1. EM Maloney1,2,3,
  2. E Chaila4,
  3. EJ O’Reilly2,
  4. DJ Costello1,3
  1. 1Neurology, Cork University Hospital, Cork, Ireland
  2. 2School of Public Health, University College Cork, Cork, Ireland
  3. 3College of Medicine and Health, University College Cork, Cork, Ireland
  4. 4Department of Neurology, University Hospital Limerick, Limerick, Ireland

Abstract

Background Epilepsy is a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychological, and social consequences of this condition [1]. Studies adherent to international epidemiologic guidelines and epilepsy classification are needed to accurately record the incidence of isolated seizures and epilepsy within a population [2]. Because the diagnosis of epilepsy is largely made through clinical assessment, seizures and epilepsy are susceptible to misdiagnosis. Previous epidemiological studies in epilepsy have not captured or explored ‘seizure mimics’.

Methods During the calendar year 2017, multiple overlapping methods of case ascertainment were applied to a defined geographic region to identify all patients presenting with first seizures (provoked and unprovoked), new diagnoses of epilepsy, and seizure mimics. Seizures among children, except neonatal seizures and febrile seizures, were included. Potential first seizures and new diagnosis of epilepsy were identified in real-time but classified retrospectively as definite, probable or possible based on available evidence in accordance with the International League Against Epilepsy (ILAE) epidemiologic guidelines [2]. Definite and probable cases of seizures and epilepsy were classified according to 2017 ILAE classification systems as focal, generalized or unknown [3, 4]. Data were analysed using SPSS, version 24.

Results From a population of 542,869 adults and children, 1942 potential cases were identified, of whom 611 were excluded as neonatal or febrile seizures, did not meet the geographic criteria or had a previous diagnosis of seizures or epilepsy. Incidence rates of first seizure (both provoked and unprovoked) was 102 per 100,000 population, of new diagnosis of epilepsy was 64 per 100,000, and of seizure mimics was 96 per 100,000. In concordance with most international studies, age-specific incidence rates for both first seizures and new diagnosis of epilepsy demonstrated a bimodal distribution, with highest rates in the very young and in later life. As expected, the most commonly encountered seizure mimic was syncope (30%).

Conclusion We applied 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 epidemiological studies and epilepsy classification. This study highlights the significant burden that seizure mimics place on diagnostic services given that they occur as frequently as first seizures.

  • Epidemiology
  • Incidence
  • Epilepsy

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