Proposed criteria of levels of evidence for co‐occurring epilepsy in people with functional/dissociative seizures

Objective This work was undertaken to describe the level of evidence for co‐occurring epileptic seizures in patients with known functional/dissociative seizures (FDS) using stratification criteria analogous to the International League Against Epilepsy criteria for functional seizures. Methods Adult patients (age 18 years) with “documented” or “clinically established” FDS seen in a health system with a multidisciplinary FDS clinic were manually evaluated by retrospective chart review to identify their risk of co‐occurring epilepsy. They were grouped into five mutually exclusive categories based on “red flags” for co‐occurring epilepsy in the clinical history, semiology of unobserved seizures, and neurodiagnostic data. The categories of concern for co‐occurring epilepsy were as follows: unlikely, possible, probable, clinically established, and documented. Results We identified 460 patients with FDS (median age = 34 years, interquartile range = 24–46 years, 78% female). The majority (62.6%, 95% confidence interval = 58%–67%) had “unlikely” co‐occurring epilepsy due to no “red flags.” Some (11.5%) patients had high likelihood of co‐occurring epilepsy: 10.2% electroencephalographically “documented” and 1.3% “clinically established.” There were 74 (16.5%) patients with neurodiagnostic “red flags” indicating “probable” co‐occurring epilepsy. The remaining 9.3% had historical reports of “red flags” indicating “possible” co‐occurring epilepsy. Significance The majority (62.6%) of people with FDS were “unlikely” to have co‐occurring epilepsy due to the lack of “red flags.” Conversely, 11.5% of patients with FDS had a high level of certainty of co‐occurring epileptic seizures (clinically established and documented). In patients with intermediate concern, patient‐centered decision‐making can guide the next steps of diagnosis and treatment.