Distinguishing between patients with pure psychogenic nonepileptic seizures and those with comorbid epilepsy by means of clinical data

• Patients with PNESs were older at disease onset.
• Patients with PNESs had a shorter duration from onset to inpatient visit.
• Patients with PNESs were less frequently on antiepileptic drugs.
• Patients with PNESs were less frequently on antiepileptic polytherapy.
• The identified differences might be used to identify patients with PNESs with comorbid epilepsy.

Patients with psychogenic nonepileptic seizures (PNESs) often have additional epileptic seizures (ESs). Distinguishing between those with ESs and those without ESs is difficult but mandatory. We hypothesize that these two patient groups differ in clinical data, which might be useful for establishing diagnosis. All patients with PNESs (n = 114) from the Bethel Epilepsy Centre treated between 1/11/2010 and 1/11/2011 were included. Thirty-six percent had additional epilepsy. In contrast, 84 of the 114 patients with PNESs took antiepileptic drugs (AEDs) (AED treatment: patients with PNESs = 44/73, patients with PNESs + ESs = 40/41), most of them (65.5%) as polytherapy. Significant differences between both groups were as follows: patients with PNESs were older at disease onset, had a shorter duration from onset to inpatient visit, were less frequently on AEDs, were less frequently on antiepileptic polytherapy, and had a normal EEG compared with patients with PNESs + ESs. Multivariate stepwise logistic regression revealed age at seizure onset, number of AEDs, and difference between number of AEDs and psychiatric drugs as significant predictors of patients with ESs in PNESs (Nagelkerke's r2 = 0.59). Therefore, clinical data proved to be useful in the diagnostic process.