Article In Brief
New research suggests failure to recognize symptoms of subtle seizures contributes to delays in diagnosing epilepsy and, when there is impaired awareness, a significantly greater risk for motor vehicle accidents.
Every day for several years, the young man had experienced brief episodes, which he later described as “hearing all the music in the world at once for 30 seconds.” All the things people around him were saying would fade out. It was only when he experienced a new-onset convulsive seizure and was referred to epileptologist Jacqueline A. French, MD, FAAN, professor of neurology at the NYU Langone Health and director of translational research and clinical trials for epilepsy, that he realized that those recurrent episodes had also been a type of seizure.
Dr. French uses the term “subtle seizures” to describe these episodes, which she defines as involving primarily motor arrest. Subtle seizures roughly correspond to the International League Against Epilepsy classification of “focal non-motor,” distinguishing them from disruptive seizures involving motor activity or disruptive vocalizations, including bilateral tonic-clonic seizures.
Dr. French and a multi-institutional group of colleagues reported in an October 20 study online in the journal Epilepsia that patients with these types of seizures experience significantly longer delays in diagnosis and, when there is impaired awareness, this produces significantly greater risk for motor vehicle accidents.
The study is among the first to pinpoint failure to recognize symptoms of subtle seizures as a main reason for delays in diagnosing epilepsy.
Study Details, Findings
Using enrollment data from the Human Epilepsy Project, which enrolled participants between June 29, 2012, and November 7, 2017, Dr. French and her colleagues classified the 447 patients analyzed as having experienced either subtle or disruptive seizures. Subtle seizures, they wrote, were “characterized by primarily motor arrest or focal awareness without motor [activity], which often were purely internal experiences, including features of cognitive, emotional, and/or sensory disturbances, but could also include automatic behaviors (automatisms) mistaken for normal reactions or ‘other’ neurologic phenomena such as tics or compulsions.”
By contrast, disruptive seizures were “characterized by motor activity or disruptive vocalizations, including bilateral tonic-clonic seizures, and were often hyperkinetic, myoclonic, or tonic, and included non-motor seizures that led to abnormal vocalizations or automatic behaviors (automatisms) with a significant motor component.”
For all patients in the study, the overall median number of days from first reported seizure to diagnosis was 219 days—but the difference between the two groups was dramatic. The 246 patients with onsets characterized by subtle seizures experienced a median delay in diagnosis of 616 days, while the 201 patients with onsets characterized by disruptive seizures experienced a median delay of 60 days (p<0.001).
The number of overall injuries did not differ significantly between the two groups—40.7 percent of patients with subtle seizures (p=0.069) experienced injury prior to diagnosis, compared with 49.3 percent of patients with disruptive seizures—nor did severity of injuries. The majority of potentially preventable motor vehicle accidents—19 or 82.6 percent; p<0.001—occurred in patients with initial subtle seizures. The number of motor vehicle accidents may even have been underestimated, the authors noted, as they relied on patients' self-reported events from months to years prior to enrollment.
“Many of these patients are getting missed in primary care settings, emergency departments, and even sometimes by neurologists,” Dr. French said. “The man who had music in his head was one patient who came to me after having been seen by other neurologists. Another woman was having episodes that she called her ‘panic attack.’ She had seen two previous neurologists, and after she had a convulsive seizure, she was treated for that, but her doctors were unaware that she was having other seizures as well, and the medications they gave her didn't stop those smaller seizures. When she came to me, she explained that during her ‘panic attacks,’ she would be driving and suddenly find her feet off the pedals. When we brought her to our monitoring unit, we recorded five such subtle seizures in two days.”
Most epilepsy specialists have seen patients like these, said Nathan B. Fountain, MD, FAAN, professor of neurology and director of the F.E. Dreifuss Comprehensive Epilepsy Program at the University of Virginia School of Medicine.
“I just recently saw someone who had had subtle seizures since childhood but wasn't diagnosed until she had her first major motor seizure in her 30s. But then she described for me strange instances like when she would be standing at the bus stop only to realize that the school bus had come and went, and she hadn't realized it.”
Quantifying and defining this type of seizure is helpful both clinically and epidemiologically, Dr. Fountain said.
Fred A. Lado, MD, director of epilepsy for Northwell Health Central and Eastern Regions, agreed. “It really is a common situation for the epileptologist that you speak to someone in the clinic who is presenting with a first seizure, and when you take the history, you find out they have been having subtle events going back years or decades. You ask what they make of that, and they say, ‘I thought everyone had something like this.’ Your subjective experience is just that, yours and people don't realize that what they're experiencing is unique or even reportable.”
“I wasn't surprised by the high proportion of patients who had subtle seizures, but the fact that there were so many motor vehicle accidents in that group, as compared to the disruptive group, is important, and that hasn't really been quantified before,” Dr. Lado said.
“We have known that motor vehicle accidents from seizures are common, and they have been looked at in different ways, but this is one of the most important, and if these types of seizures are diagnosed earlier, we can hopefully prevent injuries and even deaths. This is very significant from a public health perspective.”
Indeed, a retrospective study, performed in Canada looking at patients, who presented to a first-time seizure clinic over a three-year period, identified 158 patients with newly diagnosed epilepsy and found that 13 experienced a first seizure while driving, leading to seven accidents and one fatality.
Dr. Lado called the study, which was published in 2013 in the Canadian Journal of Neurological Sciences, a wake-up call to physicians with regard to more thorough and effective screening.
“Many physicians are more familiar with convulsive seizures and obvious behavioral manifestations, but we as neurologists should be educating our colleagues in identifying the subtler manifestations.”
That can be challenging, said Dr. Fountain. “Many people have unusual sensations that aren't seizures—in fact, I suspect the majority of people with unusual sensations aren't having seizures, so it's up to physicians to identify the characteristics that suggest that unusual, subtle symptoms are likelier to be seizures. For example, they are stereotyped, usually highly so, each time the same, and paroxysmal—coming on suddenly and stopping in a discrete episode rather than waxing and waning all day long.”
With one out of every 26 people having some form of epilepsy, Dr. French said that there is a significant opportunity for public education campaigns about subtle seizure presentations, just as there has been for conditions like stroke. She has developed a simple mnemonic for doctors and patients to use in discussing these seizures: SSSS, for short, sudden, strange spells. (A fifth S, for stereotyped, could also be added, she said.)
“If people are experiencing this, that should be a red flag that these could be seizures,” she said. “I can't tell you how big the problem is because so many people aren't aware of this. When I ask new patients if they have ‘funny spells’ that come out of nowhere, they either look at me like I have two heads, or they stare at me like I'm a prophet and say, ‘How did you know about those?’”