Abstracts

Rationale: Psychogenic non-epileptic seizures (PNES) are the final diagnosis in a significant fraction of patients diagnosed with treatment-resistant seizure disorders. Delayed diagnosis can lead to increased disability, adverse effects from unnecessary antiepileptic medications, loss of pregnancy and even death. Two European studies have examined factors that may lead to prolonged delay to diagnosis; we are unaware of any published data from a North American centre. Methods: Patient records from an adult epilepsy clinic were reviewed retrospectively, and potential cases of PNES were identified. The diagnosis of PNES was confirmed if there was documentation of a typical attack lacking features of an epileptic seizure and containing features of PNES. The event could occur in one of three situations: during stimulation with a tuning fork; during routine EEG recording; or during video-EEG monitoring. The delay to diagnosis was defined as the time from first attack to confirmation of the diagnosis of PNES. Factors that could possibly contribute to delay were determined by chart review and included patient demographics, concomitant epilepsy, referral source and reason for referral, and results of diagnostic tests. Results: From approximately 1,500 patient records, 184 potential patients were identified, and 87 met the diagnostic criteria for PNES. 21/87 (24%) had a possible diagnosis of concomitant epilepsy, but the remainder had PNES alone. The mean delay to diagnosis was 6.6 years (95% confidence interval 4.7-8.3). 69/87 (79%) of patieznts had attacks during EEG monitoring, and the remainder were diagnosed based on clinical features. Factors that had no significant effect on diagnostic delay included: patient gender, concomitant epilepsy, type of attacks, “pseudostatus”, reason for referral, source of referral, and presence of abnormalities on EEG or neuroimaging. Younger age at onset was associated with a longer delay to diagnosis (R2=0.179, p<0.001). Conclusions: The diagnostic delay for PNES in our institution was almost seven years, which is consistent with previously published data. Identification of factors that could decrease diagnostic delay may result in better patient outcomes.