Patients with epilepsy may have additional psychogenic non-epileptic seizures (PNES). It has been suggested that PNES are more common if patients with epilepsy are female, develop epilepsy later in life and have right-sided brain lesions. We examine whether these or other physical factors affect the risk of PNES in patients with epilepsy in a controlled study.
Methods: Ninety consecutive patients with PNES and concurrent epilepsy (PNES+E group) and 90 consecutive patients with epilepsy alone (epilepsy group) were compared with regard to the variables sex, age at onset of epilepsy, epilepsy type (focal/generalised), location and lateralisation of epileptogenic zone, aetiology of epilepsy, interictal epileptiform potentials, magnetic resonance imaging (MRI) abnormalities, neuropsychological (NPS) deficits and intelligence quotient (IQ).
Results: Female sex (P<0.001), abnormal visual memory (P=0.012), global NPS impairment (P=0.029), and low IQ category (P=0.005) were associated with a higher risk of PNES. Other variables did not differ between the groups.
Conclusions: In patients with epilepsy, female sex, poor visual memory or global neuropsychological underperformance and low IQ are associated with an increased risk of PNES. MRI changes, epileptiform EEG abnormalities and location of epileptogenic zone do not show a predilection for one hemisphere.