Epidemiology of Functional Seizures Among Adults Treated at a University Hospital

Abstract

IMPORTANCE Functional seizures (formerly psychogenic nonepileptic seizures), paroxysmal episodes that are often similar to epileptic seizures in their clinical presentation and display no aberrant brain electrical patterns, are understudied. Patients experience a long diagnostic delay, few treatment modalities, a high rate of comorbidities, and significant stigma due to the lack of knowledge about functional seizures. OBJECTIVE To characterize the clinical epidemiology of a population of patients with functional seizures observed at Vanderbilt University Medical Center (VUMC). DESIGN, SETTING, AND PARTICIPANTS This case-control study included patients with functional seizures identified in the VUMC electronic health record (VUMC-EHR) system from October 1989 to October 2018. Patients with epilepsy were excluded from the study and all remaining patients in the VUMC medical center system were used as controls. In total, the study included 1431 patients diagnosed with functional seizures, 2251 with epilepsy and functional seizures, 4715 with epilepsy without functional seizures, and 502 200 control patients who received treatment at VUMC for a minimum of a 3 years. Data were analyzed from November 2018 to March 2020. EXPOSURE Diagnosis of functional seizures, as identified from the VUMC-EHR system by an automated phenotyping algorithm that incorporated International Classification of Diseases, Ninth Revision (ICD-9) codes, International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes, Current Procedural Terminology codes, and natural language processing. MAIN OUTCOMES AND MEASURES Associations of functional seizures with comorbidities and risk factors, measured in odds ratios (ORs). RESULTSOf 2 346 808 total patients in the VUMC-EHR aged 18 years or older, 3341 patients with functional seizures were identified (period prevalence, 0.14%), 1062 (74.2%) of whom were women and for which the median (interquartile range) age was 49.3 (39.4-59.9) years. This assessment replicated previously reported associations with psychiatric disorders including posttraumatic stress

Diagnosis and management of functional neurological disorder

“…It is “documented” when a typical event is concurrently captured on video and EEG. Keep in mind the possibility that a patient has both FND and epilepsy, as around 20% of patients with seizure type FND also have epileptic seizures 124125…”

Health conditions associated with sexual assault in a large hospital population

“…Supplemental Table 5 Contingency tables demonstrating co-incidence of seizure-related phecodes and functional seizure cases (functional seizure phenotyping algorithm described in 10 ). For a given phenotype, “NA” corresponds to individuals excluded from case-control analyses for that phenotype (see 11 ).…”

“…Supplemental Table 6 Sex-combined associations between sexual assault and seizure-related phecodes after conditioning on functional seizures case-control status (functional seizure phenotyping algorithm described in 10 ). Here, the keyword-based sexual assault case definition was applied.…”

“…We also identify a range of urinary symptoms associated with sexual assault, consistent with prior studies linking sexual assault and genitourinary symptoms 16,17 Several phenome-wide-significant phecodes identified in our analysis pertained to seizures and epilepsy, including the broad "epilepsy, recurrent seizures, convulsions" phecode and all phecodes classified under it. Given the previously identified relationship between sexual assault and the development of functional seizures, we investigated whether these associations were partially explained by patients experiencing functional seizures as classified by our previously published phenotyping algorithm 10 . Indeed, we observed a high level of overlap between seizure-related phecodes and functional seizure status (Supplemental Table 5).…”

“…(OR=odds ratio, CI=confidence interval, ".f" = female-only analysis, ".m" = male-only analysis, ".int" = interaction analysis.) Supplemental Table 5 Contingency tables demonstrating co-incidence of seizure-related phecodes and functional seizure cases (functional seizure phenotyping algorithm described in 10 ).…”