Are there real unprovoked/unprecipitated seizures?

Seizure self-prediction: Myth or missed opportunity?

PURPOSE

Many patients report being able to predict their own seizures, and yet most seizures appear to strike out of the blue. This inherent contradiction makes the topic of seizure self-prediction controversial as well as difficult to study. Here we review the evidence for whether this ability exists, how many patients are capable of self-prediction and the nature of this capability, and whether this could provide a target for intervention.

METHODS

Systematic searches of bibliographic databases including MEDLINE, EMBASE and PsycINFO through OVID were performed to identify relevant papers which were then screened by the study authors for inclusion in the study. 18 papers were selected for inclusion as the focus of this review.

RESULTS

On the basis of two studies, between 17% and 41% of patients demonstrate a significantly greater than chance ability to predict an upcoming seizure in the following 12-h time window. This risk is correlated with self-reported anxiety, stress, sleep deprivation, mood and certain prodromal symptoms. However, there is no evidence for any subjective experience which directly heralds an imminent seizure. Thus, while patients may be aware of seizure risk, and have some ability to predict seizure occurrence over a wide time window, they are unable to subjectively recognise seizure onset in advance.

CONCLUSION

Utilising subjectively acquired knowledge of seizure risk may provide a widely implementable tool for targeted intervention. The risk fluctuates over a time course appropriate for pharmacotherapy which may improve seizure control and the side-effect profile of anti-epileptic medication.

EEG activation by neuropsychological tasks in idiopathic generalized epilepsy of adolescence

THE AIM OF THE STUDY

To evaluate the effects of neuropsychological activation (NPA) tasks on epileptiform discharges in adolescents with idiopathic generalized epilepsy (IGE) and their possible relationship to clinical epilepsy-related factors, also to compare the effects of the NPA to the habitual methods of electroencephalographic (EEG) activation.

METHODS/SUBJECTS

Fifty-nine patients with IGE aged 14-17 years underwent baseline video-EEG recording with habitual activation procedures followed by NPA tasks, and sleep EEG after sleep deprivation on the next day.

RESULTS

At least one task of NPA showed provocative effect in 18.6% of cases. There was no difference between the provocative effects of action-programming and thinking NPA task groups as well as among individual NPA tasks. The provocative effects of NPA tasks were more prevalent in photosensitive cases, especially the tasks of action-programming type (p=0.04). The provocative NPA effects showed no relationship to gender, age, age at seizure onset, duration of epilepsy, treatment status, presence of myoclonias, recent generalized tonic-clonic seizures, family history of epilepsy. The provocative effects of NPA were comparable to those of hyperventilation (23.7%) and intermittent light stimulation (30.5%) (p>0.05).

CONCLUSIONS

Although the provocative effects NPA tasks on epileptiform discharges on EEG did not outweigh the effects of the habitual activation procedures, NPA activation might be helpful as an additional diagnostic tool in adolescents with IGE in selected cases when routine EEG is not informative enough or when sleep EEG is readily unavailable, also in photosensitive cases. It may also help in providing advice for patients on safety issues.

Do reflex seizures and spontaneous seizures form a continuum? - triggering factors and possible common mechanisms

Recent changes in the understanding and classification of reflex seizures have fuelled a debate on triggering mechanisms of seizures and their conceptual organization. Previous studies and patient reports have listed extrinsic and intrinsic triggers, albeit their multifactorial and dynamic nature is poorly understood. This paper aims to review literature on extrinsic and intrinsic seizure triggers and to discuss common mechanisms among them. Among self-reported seizure triggers, emotional stress is most frequently named. Reflex seizures are typically associated with extrinsic sensory triggers; however, intrinsic cognitive or proprioceptive triggers have also been assessed. The identification of a trigger underlying a seizure may be more difficult if it is intrinsic and complex, and if triggering mechanisms are multifactorial. Therefore, since observability of triggers varies and triggers are also found in non-reflex seizures, the present concept of reflex seizures may be questioned. We suggest the possibility of a conceptual continuum between reflex and spontaneous seizures rather than a dichotomy and discuss evidence to the notion that to some extent most seizures might be triggered.

Premonitory features and seizure self-prediction: artifact or real?

Seizure prediction is currently largely investigated by means of EEG analyses. We here report on evidence available on the ability of epilepsy patients themselves to predict seizures either by means of subjective experiences ("prodromes"), apparent awareness of precipitants, or a feeling of impending seizure (self-prediction). These data have been collected prospectively by paper or electronic diaries. Whereas evidence for a predictive value of prodromes is missing, some patients nevertheless can forsee impending seizures above chance level. Relevant cues and practical implications are discussed.

Predicting seizures: a behavioral approach

This article reviews the epilepsy cycle, distinguishing the interictal, preictal, ictal, and postictal phases. Evidence suggesting that the preictal phase can sometimes be identified based on neurophysiologic signals, premonitory features, the presence of trigger factors, or self-report is also reviewed. Diary studies have shown that seizures are not randomly distributed in time and that a subgroup of persons with epilepsy can predict an impending seizure. Paper diary data and preliminary analysis of electronic diary data suggest that seizure prediction is feasible. Whereas all of this evidence sets the stage for seizure prediction and preemptive therapy, several questions remain unanswered. First, what proportion of persons with epilepsy can predict their seizures? Second, within and among individuals, how accurate is prediction? Third, can prediction be improved through education about group level or individual predictors? And finally, in a group that can make robust predictions what are the most effective interventions for reducing seizure probability at times of high risk? The answers to these questions could reduce the burden of epilepsy by making seizures predictable and setting the stage for preemptive therapy. This work could improve the understanding of epilepsy by providing a context for studying the transitions from the interictal to preictal and ictal states. More prospective studies are needed; challenges certainly exist, but as the studies discussed here demonstrate, the field is rich with promise for improving the lives of patients with epilepsy.

The lived experience of initial symptoms of and factors triggering epileptic seizures

The aim of this study was to document the self-perception of initial symptoms of and factors triggering epileptic seizures in a sample of people with epilepsy (PWE) and their carers. Among 600 participants, questionnaires were returned by 309 (51.5%), of whom 72.8% were PWE and 27.2% were carers and others. Experiencing at least one symptom prior to a seizure was reported by 86.9% of PWE and 74% of carers. The most common symptoms were a funny feeling, confusion, and anxiety. Experiencing one trigger that resulted in a seizure was reported by 89.8% of PWE and 85.5% of carers. The most common triggers were tiredness, stress, and sleep deprivation. Among PWE and their carers, 63.6% and 51.3%, respectively, indicated that they can tell when a seizure is about to occur, and 26.7% and 15.4%, respectively, indicated that they felt they could stop a seizure. The most common techniques were resting, medication, and relaxation.