Characteristics of 698 patients with dissociative seizures: A UK multicenter study

Abstract

Objective: We aimed to characterize the demographics of adults with dissociative (nonepileptic) seizures, placing emphasis on distribution of age at onset, male:female ratio, levels of deprivation, and dissociative seizure semiology.

Methods: We collected demographic and clinical data from 698 adults with dissociative seizures recruited to the screening phase of the CODES (Cognitive Behavioural Therapy vs Standardised Medical Care for Adults With Dissociative Non-Epileptic Seizures) trial from 27 neurology/specialist epilepsy clinics in the UK. We described the cohort in terms of age, age at onset of dissociative seizures, duration of seizure disorder, level of socioeconomic deprivation, and other social and clinical demographic characteristics and their associations.

Results: In what is, to date, the largest study of adults with dissociative seizures, the overall modal age at dissociative seizure onset was 19 years; median age at onset was 28 years. Although 74% of the sample was female, importantly the male:female ratio varied with age at onset, with 77% of female but only 59% of male participants developing dissociative seizures by the age of 40 years. The frequency of self-reported previous epilepsy was 27%; nearly half of these epilepsy diagnoses were retrospectively considered erroneous by clinicians. Patients with predominantly hyperkinetic dissociative seizures had a shorter disorder duration prior to diagnosis in this study than patients with hypokinetic seizures (P < .001); dissociative seizure type was not associated with gender. Predominantly hyperkinetic seizures were most commonly seen in patients with symptom onset in their late teens. Thirty percent of the sample reported taking antiepileptic drugs; this was more common in men. More than 50% of the sample lived in areas characterized by the highest levels of deprivation, and more than two-thirds were unemployed.

Significance: Females with dissociative seizures were more common at all ages, whereas the proportion of males increased with age at onset. This disorder was associated with socioeconomic deprivation. Those with hypokinetic dissociative seizures may be at risk for delayed diagnosis and treatment.

Keywords: demographics; deprivation; dissociative (nonepileptic) seizures; onset; semiology.

Conflict of interest statement

A.C. reports being a paid editor of the Journal of Neurology, Neurosurgery, and Psychiatry, and is the director of a research program on functional neurological disorders; he gives independent testimony in court on a range of neuropsychiatric topics (50% pursuer, 50% defender). M.P.R. reports funding from Xenon Pharma. J.S. reports independent expert testimony work for personal injury and medical negligence claims, and royalties from UpToDate for articles on functional neurological disorder, and runs a free nonprofit self‐help website, http://www.neurosymptoms.org. None of the other authors has any conflict of interest to disclose. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

© 2019 The Authors. Epilepsia published by Wiley Periodicals, Inc. on behalf of International League Against Epilepsy.

Figures

Figure 1

Study flowchart showing the number of patients with dissociative seizures identified in neurology/specialist epilepsy clinics and reasons for ineligibility for the study, leaving 698 recruited to the study. CBT, cognitive behavioral therapy; DSM‐IV, Diagnostic and Statistical Manual of Mental Disorders, 4th edition

Figure 2

Bar charts showing the frequency distribution of age at onset of dissociative seizures and duration of dissociative seizures in the current sample

Figure 3

Bar chart showing the frequency distribution of age at first dissociative seizure by gender (females shown in red bars, males in blue bars)

Figure 4

Clustered bar chart illustrating the distribution of quintiles of Index of Multiple Deprivation (IMD) in England, Scotland, and Wales. Quintile 1 represents least deprivation, and quintile 5 represents most deprivation. The horizontal dashed line represents the expected number of people per quintile (140 patients) if the sample is representative of the general population

Figure 5

Line graphs showing percentages of the sample reporting current antiepileptic drug (AED) use, having a previous (valid) diagnosis of epilepsy, self‐reporting previous help‐seeking for a mental health problem, and having clinician‐rated predominantly hyperkinetic dissociative seizures, in relation to age at onset of dissociative seizures