High Premature Death Rate for Psychogenic Seizures Troubling

Pauline Anderson

December 13, 2018

NEW ORLEANS — Patients with psychogenic nonepileptic seizures (PNES) have a mortality rate that is more than two times higher than the general population and die at a rate comparable with that of patients who have drug-resistant epilepsy, new research shows.

Although they resemble epileptic seizures on a superficial level, PNES have a psychiatric basis and are characterized in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) as a conversion disorder.

Up to 30% of patients admitted to tertiary epilepsy centers have psychogenic seizures, said study investigator Russell Nightscales, a medical student at the University of Melbourne in Australia.

The findings were presented here at the American Epilepsy Society (AES) 2018 Annual Meeting.

High Premature Death Rate

Although it is well known that individuals with epilepsy have an elevated risk of death compare with the general population, mortality in PNES patients has received little scientific attention, the researchers note.

The aim of the retrospective study was to comprehensively determine the rate of premature death in patients diagnosed with PNES who were admitted to three tertiary-care hospital video EEG monitoring units over a 20-year period.

Based on video EEG evidence and expert consensus, researchers stratified patients into three diagnostic groups: epilepsy, PNES, and both conditions.

From medical records, they gathered information on the psychiatric history of those with PNES. They obtained cause of death from the National Death Index in Australia.

Where available, they also used coroner and autopsy reports to capture cases of sudden unexpected death in epilepsy (SUDEP), and sudden unexpected death in those with PNES.

The analysis included 756 patients with PNES and 2895 patients with epilepsy.

The investigators found patients with PNES died at a rate 2.6 times greater than Australia's general population.

Bad Outcomes

There were no deaths in those with PNES under age 20 years, but for those ages 20 to 29 years, and 30 to 39 years, the relative mortality risk was six to seven times greater than Australia's general population, said Nightscales.

There was no significant difference in the mortality rate between those with epilepsy and those with psychogenic seizures.

"I think this finding highlights the seriousness of a PNES diagnosis and just how bad outcomes can be in these patients. It tells us, really for the first time, that their rate of death is, at the very least, comparable to those with epilepsy," he said.

About 75% of individuals with PNES had a lifetime psychiatric comorbidity, with depressive disorder the most common co-occurring condition by far. The study did not show any association between mortality and these psychiatric comorbidities.

"By definition, PNES is itself a psychiatric diagnosis," said Nightscales. "We felt that it was this diagnosis of PNES alone that was increasing the risk of premature death."

Neoplasia and cardiorespiratory causes accounted for about 40% of the mortality among individuals with PNES across all age groups. The vast majority of these deaths were among those over age 50 years and may be an indicator of poor health and lifestyle factors.

About 20% of the mortality rate in PNES patients was attributable to external causes, and 53% of deaths in those who died before age 50 were attributable to a known cause. Suicide accounted for 24% of deaths in PNES patients who were under age 50.

In those with epilepsy, external causes accounted for 7% of all deaths while neoplasia and cardiorespiratory causes accounted for 42% of cases.

'Eye-Opening' Findings

Using autopsy and coroners' reports, the researchers identified several cases of sudden unexpected deaths in PNES subjects where the death certificate listed epilepsy as the cause of death.

Following the presentation, one audience member praised the study for being "eye-opening and impressive."

But the audience member felt it "a little perplexing" that some PNES patients had epilepsy listed as a cause of death.  Epilepsy should have been "fairly well excluded" by video EEG monitoring and history, he said.

Nightscales noted that despite the lack of evidence to substantiate a diagnosis of epilepsy during video EEG monitoring, some PNES patients may indeed have epilepsy.

He added that "mislabeling" on death certificates "is possible."

Commenting on the study for Medscape Medical News, session co-chair Kelly Knupp, MD, Pediatric Neurology and Epilepsy Program, Children's Hospital Colorado, agreed that it was "incredibly well done and really fascinating."

She weighed in on the discussion about categorizing a death SUDEP in people with psychogenic seizures.

"They clearly have died suddenly of something, at a rate greater than the general population," Knupp said. "We need to figure out what that is — was it a sudden death related to something else that was misclassified as SUDEP?"

The study was funded by the National Health and Medical Research Council and the RMH Neuroscience Foundation in Australia . Nightscales and Dr Knupp have disclosed no relevant financial relationships.

American Epilepsy Society (AES) 2018 Annual Meeting: Abstract 1.139. Presented December 3, 2018.

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