The finding: Patients with psychogenic non-epileptic seizures (PNES) and epileptic seizures (ES) were compared to patients with either only PNES or ES with regards to clinical and electroencephalographic differences. In the cohort with PNES/ES, ES antedated PNES in 28 patients (70%) and occurred simultaneously in 11 (27.5%), while PNES were the initial presentation in only 1 case (2.5%); disease duration was undetermined in 6. Compared with those with ES-only, patients with PNES/ES had higher depression and anxiety scores, shorter-duration electrographic seizures, less ES absence/staring semiology (all p≤0.01), and more ES arising in the right hemisphere, both in isolation and in combination with contralateral brain regions (61% vs. 41%; p=0.024, adjusted for anxiety and depression) and tended to have less ES arising in the left temporal lobe (13% vs. 28%; p=0.054). Compared with those with PNES-only, patients with PNES/ES tended to show fewer right-hemibody PNES events (7% vs. 23%; p=0.054) and more myoclonic semiology (10% vs. 2%; p=0.073).

Strengths: The study was conducted in multiple sites across the US, Canada, and Europe and the study design included only using patients who had video EEG data which increases the specificity of diagnosis. There are “hard” findings including higher rates of right-sided EEG phenomena in patients with PNES/ES, and the clinical findings including seizure duration and seizure type/specifics could help to distinguish between co-morbid PNES/ES, ES alone, or PNES alone, especially when the diagnosis is unclear.
Weaknesses included likely selection bias (case-control study performed in may tertiary referral centers), and the type/quality of data made available in medical records may not have included pertinent data including more nuanced information on psychiatric symptoms and co-morbidities aside from general “anxiety” and “depression”. The data that was used may have been biased/confounded as the indications for vEEG monitoring may differ between patients with ES and PNES and hence interpreted differently in reports by different clinicians (ie confirmation bias is possible among other possible confounders).

Relevance: Being able to distinguish between PNES and ES is crucial. The preferred treatment modality for PNES involves CBT and/or other psychotherapeutic and psychiatric interventions while deemphasizing the use of anti-epileptic medication (AED). Patients with ES need to be treated with AEDs and/or surgery if seizures are intractable. Furthermore, being able to predict co-morbid PNES/ES with clinical and EEG features is of great value as the two do often co-exist together. The ability to differentiate between them can lead to employing different therapeutic recommendations and treatment depending on how symptoms are manifesting, thus hopefully addressing the “real” issue at hand, and sparing any untoward side effects, costs, or delays in effective management.