The importance of acknowledging clinical uncertainty in the diagnosis of epilepsy and non-epileptic events

Background: Failure to recognise diagnostic uncertainty between the epilepsies and non-epileptic events may be a factor in high rates of misdiagnosis. Aims: To explore the results of acknowledging diagnostic uncertainty in a cohort of children presenting with paroxysmal events. Methods: Children (29 days - 16th birthday) with new presentations of paroxysmal disorders were ascertained through outpatients, admissions, and accident and emergency over a two year period in a district hospital with a catchment population of 500 000. Cases were classified by diagnosis at entry and 6 - 30 months later. A random selection of cases was independently assessed. Results: A total of 684 cases were ascertained. Attacks were initially classified as febrile seizures (n = 212), acute symptomatic epileptic seizures (n = 5), epilepsies (n = 83), unclassified (possible epilepsy) (n = 90), isolated epileptic seizures (n = 51), and non- epileptic events (n = 243). Case review enabled reclassification of 61 of those initially unclassified - 31 to an epilepsy and 27 to non- epileptic events. In 29 the final diagnosis was never clarified. These were 23 cases with confusing or absent histories and six with short lived seizure clusters. Prognosis for these 29 cases was good; 75% had been discharged. None were on long term medication. The diagnosis in the 131 cases confirmed as epilepsy was stable. Independent review of a random sample showed full concordance with one neurologist and 20% uncertainty with another. Conclusion: In addition to definite epilepsy or non- epileptic events it is helpful to recognise a group of cases where the diagnosis is uncertain - unclassified paroxysmal events. Reassessment of these cases enables accurate diagnosis and may prevent a hasty and incorrect diagnosis of epilepsy.