Abstracts

Rationale: Psychogenic nonepileptic seizures (PNES) are paroxysmal events that may resemble epileptic seizures, but are not caused by abnormal brain electrical discharges. PNES are typically considered psychologically-based and most commonly thought to be categorized as a conversion disorder. PNES patients may represent 5-10% of outpatients in tertiary care epilepsy centers and 20-40% of patients admitted to inpatient epilepsy monitoring units (EMU), with a reported incidence of 1.4-4.9/100,000/year. (1)Health locus of control (HLC) is described as a patient’s belief regarding where control over his or her illness lies. (2) It is considered either internal or external. An internal HLC implies that a person credits their own actions or characteristics with shaping or changing their health, while an external HLC means an individual feels external forces, such as chance, fate, luck, or powerful other people significantly mold their health status. (2)This study addresses the question of whether there is an association between HLC and frequency of nonepileptic seizures in individuals with PNES. Our hypothesis is that in individuals with PNES, those with an external HLC as measured by the Multidimensional Health Locus of Control Form C (MHLC) will have a higher frequency of nonepileptic seizures per month as compared to those with an internal HLC. Methods: Patients were identified and recruited from the University of Maryland Epilepsy Monitoring Unit (EMU) between 2006 and 2013. Patients with a diagnosis of PNES as determined by their EMU data, including video-electroencephalogram (VEEG) were considered eligible.All subjects were 18 or more years of age, with a Mini-Mental State Examination (MMSE) score greater than 23. Exclusion criteria included co-existing epileptic seizures and those subjects who were missing data on the exposure and/or outcome of interest, specifically HLC and PNES frequency. Subjects completed demographic questionnaires along with assessments of psychological, cognitive, and social functioning. The study outcome was a self-reported count of PNES frequency per month. Patients completed the MHLC Form C., an 18-item, general purpose condition-specific HLC scale that is adaptable for use with medical or health-related conditions. (2) There are four subscales of the MHLC: 1. Internal, 2. Chance, 3. Doctors, 4. Other powerful people. (2). Higher scores in each subscale indicate a stronger belief in that type of control. For the current analysis, HLC was transformed into a categorical variable and Individuals were categorized as internal, chance, or powerful others based on their highest MHLC subscale score. Subjects with chance HLC were ultimately excluded as were those with equal MHLC scores on the internal and chance, and internal and powerful others domains due to small numbers of subjects in these categories. The final HLC categories included in the analysis were internal and powerful other HLC.This is a cross-sectional analysis and we utilize a Poisson regression model to investigate the association between HLC attribution and PNES frequency. Results: 38 subjects with PNES were included. The study population was largely women (n=32, 84.2%), with mean age of 40.3 years. Mean PNES frequency was 16.7 per month. HLC attribution was as follows: internal (n=10, 26.3%) and powerful others (n=28, 73.7%). The powerful others group, an external domain, had a rate of PNES/month 1.15 times that of those with an internal HLC, which was not found to be significant on unadjusted analysis. However, when stratified by depression category, amongst those with mild-moderate depression the rate of PNES/month for the powerful others group was 1.69 times that of the internal group. Comparatively amongst those with moderate-severe depression, the rate ratio for PNES/month was 0.95 for the powerful others group compared to the internal group. In the final model, when controlling for sex and education level, amongst subjects with minimal to mild depression, those with a powerful others HLC have a 1.89 times higher rate of PNES per month as compared to those with an internal HLC. Amongst subjects with moderate to severe depression, there is not a significant association between HLC and the rate of PNES per month. Conclusions: Amongst our study population, the most common HLC attribution was powerful others, an external domain. The association between HLC and PNES frequency varied by level of depressive symptoms. Among those with mild to moderate depression there was a higher rate of PNES per month in those with a powerful others HLC as compared to those with an internal HLC. References1. Asadi-Pooya AA, Sperling MR. Epidemiology of psychogenic nonepileptic seizures. Epilepsy Behav. 2015;46:60-65.2. Wallston KA, Stein MJ, Smith CA. Form C of the MHLC scales: a condition-specific measure of locus of control. J. Pers Assess. 1994;63:534-53. Funding: None.