Simultaneous occurrence of nonepileptic and epileptic seizures during a single period of in-patient video-electroencephalographic monitoring

Epilepsy and psychogenic nonepileptic seizures (PNES) can coexist and may present intwo forms: sequential and simultaneous. In sequential presentations, epileptic seizures(ES) are treated and PNES emerge later. Simultaneous recording of ES and PNES byvideo-electroencephalogram (vEEG) is less well described. We retrospectivelyreviewed all patients diagnosed with PNES by vEEG following standard seizure induc-tion practices over a 21-month period. Within this cohort, we established the preva-lence of coexisting epilepsy using clinical and electrographic data acquired from ourepilepsy-specific patient record. We identified patients with simultaneous PNES andES recorded during a single vEEG admission, establishing the frequency and emergenttiming of each type. Of our 262 monitored patients, 59 were diagnosed with PNES.Nineteen of the patients with PNES had coexisting epilepsy (prevalence rate of 7.3% or32% of those with PNES). Sixteen patients had PNES and ES recorded during the same admission, and the remaining three patients had sequential PNES following successfultreatment of ES. PNES occurred earlier (mean, within 1.21 days), with ES occurring later (mean, within 4.86 days). The simultaneous occurrence of PNES and ES recorded during a single admission is more common than previously reported. Identifying this group of patients may require a significantly longer period of vEEG monitoring and a detailed analysis of each individual’s historical seizure events.