WASHINGTON, DC— Researchers have developed an objective score that has the potential to be an early outpatient screening tool for identifying psychogenic non-epileptic seizures (PNES). Findings from the study were presented at the 2017 American Epilepsy Society Annual Meeting, December 1-5, 2017 in Washington, DC.
“[PNES] has been associated with a history of sexual abuse, mild traumatic brain injury, and other significant historical events, but there is a long delay to diagnosis of PNES during which patients are treated as if they have epileptic seizures,” the researchers wrote. “Therefore, novel, low-cost and objective tools based on these factors may assist in early identification of patients at risk for PNES.”
Using data from 1375 patients with diagnoses confirmed via video-electroencephalography (vEEG), the researchers used logistic regression to compare the frequency of specific patient-reported historical events, demographic information, age of onset, and delay from first seizure until vEEG, in 5 mutually exclusive groups of patients: epileptic seizures (ES), PNES, physiologic nonepileptic seizure-like events (PSLE), mixed PNES plus ES, and inconclusive monitoring.
To evaluate whether there was diagnostic utility in using their score to differentiate between PNES only and ES only, the researchers used multivariate piecewise-linear logistic regression, trained using retrospective data from chart review, and validated based on data from 246 prospective standardized interviews.
The researchers’ objective score had a prospective sensitivity of 74% (95% CI, 70-79%), and a prospective specificity of 71% (95% CI, 64-82%).
The significant factors positively associated with ES in the multivariate piecewise-linear sex-split predictive model were a history of febrile seizures, current employment or active student status, history of traumatic brain injury, and longer delay from first seizure until VEEG.
Significant factors associated with PNES were female sex, older age of onset, concussion, and significant stressful events. Sexual abuse in particular increased the likelihood of PNES. Factors that had no additional effect on the likelihood of PNES were delays longer than 20 years, age of onset greater than 31 years for men, and age of onset greater than 40 years for women.
The score system the researchers developed is as follows:
Approximate Individual-Level Predictive Score
- Time since first seizure: <20 years = -4/d
- Time since first seizure: ≥20 years = -8
- Female age of onset: <40 years = 5+2/d
- Female age of onset: ≥40 years = +12
- Male age of onset: <30 years = +2/d
- Male age of onset: ≥30 years = +6
- Febrile Seizure: -5
- Employed or student: -2
- Head Injury? Concussion: +3
- Head Injury? No concussion: -4
- Psychological stressor? Sex abuse: +14
- Psychological stressor? No sex abuse: +5
A total score of >7 indicates PNES; a total score of ≤7 indicates ES.
The researchers concluded that this objective score has potential as an early outpatient screening tool for PNES when considered with other factors. They also found individual characteristics that may be strong indicators of PNES or that may increase the risk of PNES.
“Our analysis suggests that sexual abuse, more than other psychological stressors including physical abuse, is more associated with PNES,” the researchers wrote. “[In addition,] there was a trend of increasing frequency of PNES … seen for women during childbearing years and plateauing outside those years that was not observed in men, suggesting a possible role for cumulative female sex hormone exposure in the onset of PNES.”
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Kerr W, Janio E, Braesch C, et al. An objective score to identify psychogenic seizures based on age of onset and history. Presented at: 2017 American Epilepsy Society Annual Meeting. December 1-5, 2017; Washington, DC. Abstract 1.169.