Psychogenic non-epileptic seizures with and without epilepsy: Exploring the influence of co-existing psychiatric disorders on clinical characteristics and outcomes

Background and objectives: Psychogenic non-epileptic seizures (PNES) are commonly associated with co-existing psychiatric disorders. The relationship between psychiatric factors and PNES episodes with and without epilepsy remains understudied. We reviewed co-existing psychiatric disorders in PNES-only, PNES with epilepsy aiming to examine whether these co-existing disorders associated with PNES clinical presentation and long-term outcomes.

Methods: We conducted a retrospective, longitudinal cohort study of patients with PNES diagnosed at our EMU from May 2000 to April 2008, with follow-up clinical data until September 2015. We categorized patients into three groups: PNES-only, PNES+ definite epilepsy, and PNES+ possible/probable epilepsy.

Results: In total, 271 patients with PNES were identified: 194 had PNES-only, 30 had PNES+ possible or probable epilepsy, and 47 had PNES+ definite epilepsy. No significant differences were observed in the prevalence of depression, anxiety, post-traumatic stress disorder (PTSD), substance abuse, or suicidal thoughts among the three groups. Similarly, no differences in co-existing psychiatric disorders characteristics were discovered among patients grouped by various durations and frequencies of PNES episodes. At EMU admission, for PNES-only patients total of 130/194 patients (67%) were on ASMs, and 64/194 (32.9%) were not. PNES-only not on ASM were the most likely to report at least two of the three main psychiatric disorders (depression, anxiety, and PTSD; p = 0.01). At the final follow-up, 68/130 (52.3%) and 92/130 (70.8%) patients were able to discontinue or reduce their ASM intake, respectively, with no significant differences in co-existing psychiatric disorders among them (p < 0.001). Overall, 51.6% or 31.3% of patients reported reduced or resolved PNES episodes, respectively. Further, this reduction and resolution of PNES episode were not affected by any psychological variable.

Conclusions: Co-existing psychiatric disorders prevalence did not differ between patients with PNES-only and those with coexisting epilepsy. Further, co-existing psychiatric disorders characteristics did not reliably predict PNES episode duration, frequency, reduction, or resolution. For patients with PNES-only, the presence of co-existing psychiatric disorders did not predict the rate at which ASMs could be reduced or discontinued.