Abstracts

Rationale: PNES is the most common functional neurological disorder, affecting 20-40% of patients in epilepsy monitoring units (EMUs). Distinguishing PNES from epileptic seizures (ES) may be challenging, furthermore complicated by the coexistence of both types of seizures in 12-22% of cases. Given the inherent difficulties of this dual diagnosis, we aimed to identify baseline predictors distinguishing patient with PNES-only from those with PNES and ES.

Methods: We performed a retrospective chart review of demographic and basal clinical data in those patients diagnosed with PNES by video-EEG (vEEG) telemetry in our EMU between May 2000 and February 2010. Patients were classified, according to the clinical, EEG and neuroimaging data, into PNES-only, PNES and possible or probable ES, and PNES and definite ES.

Results: 271 consecutive patients were included: 194 with PNES-only, 30 PNES and possible or probable ES, and 47 with PNES and definite ES. The mean age at time of EMU admission was 37.4 years ± 13.5 years and 73.8% of patients were female. Psychiatric disorders were present in 100% of patients in all groups, the most common being depression (72%), anxiety (53%), and history of emotional, physical or sexual abuse (27%).

Patients with PNES and definite ES were significantly most likely to have never worked, and had more frequently history of febrile seizures, structural brain abnormalities, developmental delay, and more risk factors for epilepsy—or at least one, two or three risk factors. They also reported more frequently a maximum spell duration of less than 2 minutes and least likely of more than 10 minutes (all p < 0.05).

On the other hand, patients with PNES-only, were on fewer anti-seizure medications [1 (IQR 0-2) vs 2 (2-3)], reported more frequently a minor head trauma preceding the first PNES and had a higher number of neurological and medical illnesses [1 (0-1) vs 0 (0-1) and 2 (0-3) vs 0 (0-2)], being migraine (18.1%) and other types of headaches or cranial neuralgias (18.5%) the most common neurological comorbidities, and chronic pain (15.1%) and asthma (15.5%) the most prevalent medical comorbidities. Specifically, the prevalence of migraine was significantly higher in PNES-only than PNES + definite ES group. All p < 0.05.

On the hierarchical regression analysis, the presence of definite ES was associated with history of febrile seizures (OR 4.7, 95% CI 1.2-18.0), developmental delay (OR 4.7, 95% CI 1.2-19.2), the presence of a structural brain abnormality in the MRI (OR 10.4, 95% CI 4.2-26), and longest reported spell duration between 30 seconds and 2 minutes (OR 8.2, 95% CI: 2.6-26.1); whereas having another neurological comorbidity (OR 0.3, 95% CI: 0.1-0.7) was associated with PNES-only (all p < 0.05).