Abstracts

Rationale: Psychogenic nonepileptic seizures (PNES) carry a significant burden of illness with an impact on quality of life comparable to epileptic seizures (ES). PNES diagnosis can be challenging, especially when comorbid with ES (PNES+ES). The literature comparing PNES-only and PNES+ES patients is limited by small sample sizes and inadequately rigorous criteria for ES diagnosis. Our study characterized a large cohort of PNES patients to assess the similarities and differences between patients with PNES-only and PNES+ES.Methods: We prospectively enrolled consecutive patients admitted to the Epilepsy Monitoring Unit (EMU) at London Health Sciences Centre between May 2000 and April 2008. Retrospective chart analysis included patients with 1) final diagnosis of PNES or PNES+ES, 2) minimum of two captured habitual spells or single episode of psychogenic status epilepticus, 3) spells confirmed by an epilepsy specialist to have EEG and semiology consistent with PNES (and not consistent with seizure from a deep focus or movement disorder). Comorbid ES was diagnosed in cases featuring past or present spells with semiology distinct from the PNES and either 1) electrographic seizure on EEG or 2) the combination of clinical, neuroimaging, and EEG evidence compelling for a diagnosis of true epilepsy. Statistical comparison of characteristics of PNES and PNES+ES groups was made using Fisher exact test for categorical variables and t-test for continuous variables.Results: Of 231 patients included, 23% had PNES+ES. Both PNES and PNES+ES groups had similar profiles for age (mean 37 years), gender (76% female), marital status, children, education, unemployment rate, and frequencies of psychiatric, general medical, and neurologic comorbidities (other than seizure risk factors). Seizure risk factors were present in significantly more PNES+ES patients (50% vs 25%, p=0.0006) with a preponderance of developmental abnormalities as compared to the PNES-only group, which had more CNS trauma and infection. PNES+ES patients had longer EMU admissions (mean 9.2 vs 6.5 days, p=0.004) and higher rates of prior admissions (31% vs 8%, p<0.0001). The two groups had similar spell frequency at admission and in the EMU (mean 1.9 vs 1.6 spells per day in the EMU). At admission, PNES+ES patients were on more antiepileptic drugs (AEDs) (2.1 vs 1.4, p<0.0001). In those patients who were on one or more AEDs at admission, both groups had a reduction in AEDs by the time of discharge, but a greater reduction occurred in the PNES-only group (-1.2 vs -0.6, p=0.0005). Of the patients with documented follow-up data (n=134), approximately one quarter in both groups had resolution of their spells at follow-up.Conclusions: Characteristics distinguishing patients with PNES+ES from those with PNES-only were 1) greater likelihood of seizure risk factors and higher number of AEDs, 2) longer admission and higher likelihood of multiple admissions for diagnosis. Both groups had reductions in AEDs post-EMU, but a greater reduction was achieved in the PNES-only group, while still attaining a similar level of PNES resolution.