The Invited Science Session will feature 20-minute platform presentations from authors of five groundbreaking studies presented at the American Epilepsy Society’s recent Annual Meeting.
In the first session, Brian D. Moseley, MD, will discuss breakthrough findings that may lead to a noninvasive device for predicting convulsive seizures. The unpredictable nature of epilepsy could greatly impacts independence and self-care among individuals with epilepsy.
A number of studies have suggested that increased cerebral blood flow may precede convulsive seizures, and that these increases might be detected via noninvasive devices known as transcutaneous regional cerebral oxygen saturation (rSO2) sensors.
Moseley and colleagues performed a retrospective analysis of video EEG and rSO2 data from five patients to determine if convulsive seizures are in fact consistently marked by cerebral oxygenation. Their findings reveal significantly higher rSO2 measurements in pre-seizure versus non-seizure periods. The authors report that increased cerebral blood flow was noted an average of 18 minutes and 30 seconds before seizure onset, as measured by EEG, and resolved before the seizure began.
“If our findings are confirmed in larger studies of people with epilepsy, they could dramatically improve quality of life by allowing patients to take extra medication or other precautions when they receive warnings that a seizure is more likely to occur,” says Dr. Moseley. “One might imagine someone with epilepsy receiving a warning that they are at high risk of having a seizure while driving, allowing them to pull to the side of the road, stop their vehicle, and call for help. The potential of such technology to give people living with uncontrolled seizures renewed control over their lives and independence cannot be understated.”
In a second session, Vineet Punia, MD, will present an analysis of potential factors that impair driving in people with epilepsy and in people who experience “seizure-like” non-epileptic events.
People with epilepsy often struggle with limited independence due to state and federal driving restrictions. Punia and colleagues evaluated factors that could potentially impair driving and cause motor vehicle accidents in people with medically refractory epilepsy.
Using a Multicenter Epilepsy Surgery database, the authors identified 533 people with epilepsy who shared similar demographic and clinical features. The participants were divided into two groups: those who had seizures while driving that led to a motor vehicle accident (MVA) (i.e., the ‘accident’ group) and those who had seizures while driving but did not have a MVA (i.e., the ‘no-accident’ group).
Nearly 39% of the study population reported having at least one seizure while driving, including 141 ‘accident’ participants and 74 ‘no-accident’ participants. Researchers found that patients who had auras or warnings preceding their seizures had the same accident rate as patients without reliable auras. The study further found that longer-lasting auras continuing for more than 1 minute in duration did not reduce accident risk.
“Many neurologists and patients with epilepsy believe that reliable auras provide some protection from having an MVA during seizures,” Dr. Punia notes. “Our multicenter database analysis suggests no such protective benefit of reliable auras.”
Patients with post-ictal periods lasting longer than 1 minute had a higher likelihood of seizure-related MVA than other patients, the authors report. The frequency of motor impairments such as convulsions and serious disruptive automatism did not significantly differ between the two groups.
In a third study, Sánchez Fernández, MD, and colleagues analyzed published literature detailing death rates in the general population, higher death rates in patients with epilepsy, death rates around the time of epilepsy surgery, complications of epilepsy surgery, and the probabilities of transitioning from refractory epilepsy to seizure freedom – and from seizure freedom to refractory epilepsy – in patients who underwent surgery versus non-surgical medical treatment.
A model based on their analysis reveals that surgery may increase the likelihood of a longer life in some pediatric patients with epilepsy. The authors estimate that the life expectancy of patients treated surgically might be 5 to 6 years longer than patients who received nonsurgical medical treatment. The results remained consistent across a range of patient and treatment variables, and across a variety of methods for evaluating the results.
“The information for the model came exclusively from the existing literature,” says Dr. Sánchez Fernández. “Our model just quantifies the magnitude of the advantage that epilepsy surgery conveys, in terms of years of life expectancy. It also reveals how robust this advantage is.”
In a fourth session, Jonathan Miller, MD, will present an SEEG analysis of patients with temporal lobe epilepsy who have normal MRI images and memory scores, which are generally thought to point to an extramesial or extratemporal source of the seizures.
The study revealed interictal SEEG abnormalities in the mesial temporal structures of 94% of the patients studied, while 33% had abnormalities in the lateral temporal neocortex. Interestingly, the authors did not observe seizure activity arising from any extratemporal location. All patients received temporal lobe surgery tailored to the SEEG findings, and all experienced significant improvement in seizure frequency at least one year postoperatively.
According to the authors, the findings shift three major paradigms by demonstrating that normal memory does not preclude mesial temporal seizure onset; that seizures can stem exclusively from mesial temporal structures without early neocortical involvement, even in the absence of memory deficits; and that extratemporal seizure onset is rare when vEEG and semiology are consistent with focal temporal lobe epilepsy.
“SEEG has dramatically improved our ability to localize the epileptogenic zone in cases of MRI-negative epilepsy,” says Dr. Miller. “Our research confirms that extratemporal seizure onset is rare when semiology and EEG are consistent with temporal lobe seizures, even when memory and imaging are completely normal.”
In the final presentation of the Invited Science Session, Hal Blumenfeld, MD, PhD, will unveil important clues about the relationship between behavioral performance and neural networks in children with absence seizures.
“Childhood absence epilepsy has significant effects on the quality of life of patients,” notes Dr. Blumenfeld. “Understanding how absence seizures impair consciousness may lead to improved treatments for this disorder.”
Previous studies have revealed that children with absence seizures experience brief moments of impaired consciousness marked by 3-4 Hz spike and wave discharge on electroencephalography. Neuroimaging studies point to the involvement of both cortical and subcortical networks during these seizures, but the link between consciousness and neural activity remains unclear.
Blumenfeld and colleagues performed two studies to clarify this relationship. In one study, the authors measured simultaneous behavioral, 32-lead EEG, and fMRI signals in 36 patients. In another study, the authors measured simultaneous high-quality 256-lead EEG recordings as 15 patients performed a repetitive tapping task and a more difficult continuous performance task.
Task difficulty and longer seizure durations were predictive of more impaired ictal performance, the authors report. Three neural networks – the default mode network, the task-positive network, and the primary sensorimotor and thalamic network – were sequentially activated in seizures and showed greater amplitude changes for seizures with worse performance, suggesting roles in behavioral performance. Interestingly, the authors report that EEG and fMRI signal amplitude was greater for seizures with poor performance at or prior to seizure onset.
The link between seizure amplitude and behavioral performance at seizure onset suggests that the pre-ictal state may determine both seizure severity and the degree of behavioral impairment during absence seizures, the authors conclude.
About EpilepsyThe epilepsies affect 50 million people worldwide, including three million in the United States. The disorder can have a single specific, well‐defined cause, such as a head injury, or manifest as a syndrome with a complex of symptoms. It is the third most common neurological disorder after Alzheimer’s disease and stroke.
About the American Epilepsy Society The American Epilepsy Society is a medical and scientific society whose members are professionals engaged in both research and clinical care for people with epilepsy from private practice, academia and government. For more than 75 years, AES has been unlocking the potential of the clinical and research community by creating a dynamic global forum where professionals can share, learn and grow. AES champions the use of sound science and clinical care through the exchange of knowledge, by providing education and by furthering the advancement of the profession. For additional information, visit aesnet.org.###
Information Contacts:Natalie Judd, Big Voice Communication, 203-389-5223, [email protected] Ellen Cupo, Big Voice Communication, 203-389-5223, [email protected]
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