Latency to First Event is Shorter in Psychogenic Non-epileptic Seizures than in Epileptic Seizures in an Epilepsy Monitoring Unit

Abstract

Objective: The objective was to study latency to first event among patients with psychogenic nonepileptic seizures compared (PNES) to epileptic seizures (ES) in an epilepsy monitoring unit (EMU). Introduction: PNES are common imitators of ES. This study investigates latency to first event in patients with PNES compared to patients with ES. Methods: We performed a retrospective chart review of patients admitted to our EMU from March 2016 to October 2017. We identified patients with PNES and ES. Patients with other nonepileptic events and mixed PNES (epilepsy plus PNES) were excluded. Patient demographics, baseline seizure frequency, length of EMU stay and time from admission to first event were recorded. Results: In total, 111 patients with PNES and 121 patients with ES were included. The mean age (in years) was 42 and 38, respectively. The average baseline seizure frequency was four times higher in the PNES group than the ES group. Greater than half (52%) of the patients with PNES and about one third (38%) of the patients with ES had an event within the first 24 hours. The average time to first event was 20.88 hours for the PNES group and 30.99 hours for the ES group (p<0.01). The median latency to first event was 14 hours for the PNES group and 23 hours for the ES group. The average length of EMU stay was significantly longer in the ES group (70.82 hours) than the PNES group (53.95 hours). Conclusion: The average time to first event is shorter for PNES than in ES. In patients with high pre-EMU clinical suspicion for PNES, relatively shorter EMU monitoring (24 to 48 hours) can confirm diagnosis. This phenomenon might improve cost-effectiveness of EMU monitoring in patients with PNES.

Keywords: Psychogenic nonepileptic events (PNES); epilepsy monitoring unit (EMU); epileptic seizures (ES); latency to first event; risk factors.