Saturday, December 26, 2020

Subtle seizures

 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…

“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.”…

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…

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.”

Pellinen J, Tafuro E, Yang A, Price D, Friedman D, Holmes M, Barnard S, Detyniecki K, Hegde M, Hixson J, Haut S, Kälviäinen R, French J; Human Epilepsy Project Co-Investigators. Focal nonmotor versus motor seizures: The impact on diagnostic delay in focal epilepsy. Epilepsia. 2020 Dec;61(12):2643-2652. doi: 10.1111/epi.16707. Epub 2020 Oct 19. PMID: 33078409.


Objective: To test the hypothesis that people with focal epilepsy experience diagnostic delays that may be associated with preventable morbidity, particularly when seizures have only nonmotor symptoms, we compared time to diagnosis, injuries, and motor vehicle accidents (MVAs) in people with focal nonmotor versus focal seizures with motor involvement at epilepsy onset. 

Methods: This retrospective study analyzed the enrollment data from the Human Epilepsy Project, which enrolled participants between 2012 and 2017 across 34 sites in the USA, Canada, Europe, and Australia, within 4 months of treatment for focal epilepsy. A total of 447 participants were grouped by initial seizure semiology (focal nonmotor or focal with motor involvement) to compare time to diagnosis and prediagnostic injuries including MVAs. 

Results: Demographic characteristics were similar between groups. There were 246 participants (55%) with nonmotor seizures and 201 participants (45%) with motor seizures at epilepsy onset. Median time to diagnosis from first seizure was 10 times longer in patients with nonmotor seizures compared to motor seizures at onset (P < .001). The number and severity of injuries were similar between groups. However, 82.6% of MVAs occurred in patients with undiagnosed nonmotor seizures. 

Significance: This study identifies reasons for delayed diagnosis and consequences of delay in patients with new onset focal epilepsy, highlighting a treatment gap that is particularly significant in patients who experience nonmotor seizures at epilepsy onset.

Pohlmann-Eden B, Hynick N, Legg K. First seizure while driving (FSWD)--an underestimated phenomenon? Can J Neurol Sci. 2013 Jul;40(4):540-5. doi: 10.1017/s0317167100014633. PMID: 23786737.


Background: Seizures while driving are a well known occurrence in established epilepsy and have significant impact on driving privileges. There is no data available on patients who experience their first (diagnosed) seizure while driving (FSWD). 

Method: Out of 311 patients presenting to the Halifax First Seizure Clinic between 2008 and 2011, 158 patients met the criteria of a first seizure (FS) or drug-naïve, newly diagnosed epilepsy (NDE). A retrospective chart review was conducted. FSWD was evaluated for 1) prevalence, 2) clinical presentation, 3) coping strategies, and 4) length of time driving before seizure occurrence. 

Results: The prevalence of FSWD was 8.2%. All 13 patients experienced impaired consciousness. Eleven patients had generalized tonic-clonic seizures, one starting with a déjà-vu evolving to visual aura and a complex partial seizure; three directly from visual auras. Two patients had complex partial seizures, one starting with an autonomic seizure. In response to their seizure, patients reported they were i) able to actively stop the car (n=4, three had visual auras), ii) not able to stop the car resulting in accident (n=7), or iii) passenger was able to pull the car over (n=2). One accident was fatal to the other party. Twelve out of 13 patients had been driving for less than one hour. 

Discussion: FSWD is frequent and possibly underrecognized. FSWD often lead to accidents, which occur less if preceded by simple partial seizures. Pathophysiological mechanisms remain uncertain; it is still speculative if complex visuo-motor tasks required while driving play a role in this scenario.

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