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

Abstract

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 (Formula presented.) 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.