Levels of Evidence of Comorbid Epileptic Seizures in Patients with Functional Seizures.
Shruti Iyer1, Gabriela Figueiredo Pucci1, Katherine McFarlane1, Alex Israel1, Danielle Carns1, Lianne Vighetti1, Brittany Concilus1, Wesley Kerr1
1University of Pittsburgh Medical Center
Objective:
To describe the clinical evidence of comorbid epileptic seizures in patients with known functional (nonepileptic) seizures.
Background:
Cessation of anti-seizure medications in patients with established functional seizures has been shown to confirm the diagnosis, increase patient satisfaction, and improve seizure outcomes. Published literature reports a wide variation in the rate of comorbid epilepsy, ranging from 10% to 60%. Our goal was to assess how often factors that raise the suspicion of comorbid epilepsy are observed in patients with functional seizures. We also propose diagnostic criteria for comorbid epilepsy, which may help in patient counseling and promote more judicious use of anti-seizure medications.
Design/Methods:
We conducted a retrospective chart review of adult patients with known functional seizures, classified with International League Against Epilepsy (ILAE) certainty as either "Clinically Established" or "Documented." We sought to identify factors linked to comorbid epilepsy in their clinical history, observed seizure semiology, neuroimaging, and EEG findings. The certainty of comorbid epilepsy was categorized into five levels: Unlikely, Possible, Probable, Clinically Established, and Documented, based on varying levels of evidence.
Results:
We included 100 patients with functional seizures (median age 37, interquartile range 28-48; 78% female). The certainty of comorbid epilepsy was deemed unlikely in 64%, possible in 10%, probable in 13%, clinically established in 2%, and documented in 11%. The most common clinical factor that made comorbid epilepsy "possible" was nocturnal events. Interictal epileptiform discharges resulted in comorbid epilepsy being classified as "probable" in 11% of cases.
Conclusions:
Although EEG-documented comorbid epilepsy was uncommon (11%) among patients with functional seizures, 36% of patients had some evidence suggesting comorbid epilepsy. Variations in the levels of evidence may explain the differing rates of comorbid epilepsy reported in the literature. Long-term follow-up is required to determine which patients may benefit from anti-seizure medications.
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