Safety of long-term video-electroencephalographic monitoring for evaluation of epilepsy

Seizure Clusters: Morbidity and Mortality

Seizure clusters, an intermediate between single seizure and status epilepticus, are associated with morbidity, impaired quality of life, and premature mortality. The relationship between seizure clusters and sudden unexplained death in epilepsy (SUDEP) is poorly understood. Here, we define seizure clusters; review comorbid psychiatric disorders and memory deficits associated with seizure clusters; and review cases of witnessed SUDEP for which seizure frequency prior to death is available. Patients with a history of seizure clusters have a 2.5 fold increased risk for SUDEP, and one third of patients with monitored in hospital SUDEP experienced a cluster of generalized tonic clonic seizures prior to death. Understanding the effects of seizure frequency and duration on SUDEP risk could yield new insights in SUDEP pathophysiology and new targets for intervention.

Accuracy and Safety of Customized Stereotactic Fixtures for Stereoelectroencephalography in Pediatric Patients

Stereoelectroencephalography (SEEG) in children with intractable epilepsy presents particular challenges. Their thin and partially ossified cranium, specifically in the temporal area, is prone to fracture while attaching stereotactic systems to the head or stabilizing the head in robot's field of action. Postponing SEEG in this special population of patients can have serious consequences, reducing their chances of becoming seizure-free and impacting their social and cognitive development. This study demonstrates the safety and accuracy offered by a frameless personalized 3D printed stereotactic implantation system for SEEG investigations in children under 4 years of age. SEEG was carried out in a 3-year-old patient with drug-resistant focal epilepsy, based on a right temporal-perisylvian epileptogenic zone hypothesis. Fifteen intracerebral electrodes were placed using a StarFix patient-customized stereotactic fixture. The median lateral entry point localization error of the electrodes was 0.90 mm, median lateral target point localization error was 1.86 mm, median target depth error was 0.83 mm, and median target point localization error was 1.96 mm. There were no perioperative complications. SEEG data led to a tailored right temporal-insular-opercular resection, with resulting seizure freedom (Engel IA). In conclusion, patient-customized stereotactic fixtures are a safe and accurate option for SEEG exploration in young children.

Characteristics of large patient-reported outcomes: Where can one million seizures get us?

Objective

To analyze data from Seizure Tracker, a large electronic seizure diary, including comparison of seizure characteristics among different etiologies, temporal patterns in seizure fluctuations, and specific triggers.

Methods

Zero‐inflated negative binomial mixed‐effects models were used to evaluate temporal patterns of seizure events (during the day or week), as well as group differences in monthly seizure frequency between children and adults and between etiologies. The association of long seizures with seizure triggers was evaluated using a mixed‐effects logistic model with subject as the random effect. Incidence rate ratios (IRRs) and odds ratios were reported for analyses involving zero‐inflated negative binomial and logistic mixed‐effects models, respectively.

Results

A total of 1,037,909 seizures were logged by 10,186 subjects (56.7% children) from December 2007 to January 2016. Children had more frequent seizures than adults did (median monthly seizure frequency 3.5 vs. 2.7, IRR 1.26; p < 0.001). Seizures demonstrated a circadian pattern (higher frequency between 07:00 a.m. and 10:00 a.m. and lower overnight), and seizures were reported differentially across the week (seizure rates higher Monday through Friday than Saturday or Sunday). Longer seizures (>5 or >30 min) had a higher proportion of the following triggers when compared with shorter seizures: “Overtired or irregular sleep,” “Bright or flashing lights,” and “Emotional stress” (p < 0.004).

Significance

This study explored a large cohort of patients with self‐reported seizures; strengths and limitations of large seizure diary databases are discussed. The findings in this study are consistent with those of prior work in smaller validated cohorts, suggesting that patient‐recorded databases are a valuable resource for epilepsy research, capable of both replication of results and generation of novel hypotheses.

Personalized safety measures reduce the adverse event rate of long-term video EEG

Objective

Safety in epilepsy monitoring units (EMUs) has become an increasing concern because adverse events occur in up to 10% of patients undergoing long‐term video EEG in EMUs. The aim of this study was to assess the effectiveness of a specific safety protocol in an EMU.

Methods

We retrospectively assessed the adverse event rates in a group without (group 1, 84‐month period, Innsbruck, Austria) and a group with (group 2, 33‐month period, Salzburg, Austria) personalized safety measures utilizing a standardized protocol for long‐term epilepsy monitoring in high‐risk patients. Differences in adverse event rates during and after long‐term video EEG between the two groups were calculated and compared.

Results

In group 1, 44/507 (9%, 95% confidence interval [CI] 6.5–11.5%) patients experienced 53 adverse events: 20/507 (4%, 95% CI 2.6–6.0%) patients had psychiatric events, 15/507 (3%, 95% CI 1.8–4.8%) patients sustained a total of 19 injuries during seizures, and 10/507 (2%, 95% CI 1.1–3.6%) patients had 13 episodes of status epilepticus; one adverse event was treatment‐related (valproic acid–induced encephalopathy; 1/507, 0.2%, 95% CI 0.0–1.1%). By using the new safety protocol in group 2, the adverse event rate was only 5% (95% CI 3.4–7.6%; 30 adverse events in 26/491; 45% reduction; p = 0.036), in contrast. These events included 13 psychiatric complications in 13/491 (2%, 95% CI 1.6–4.5%, p = 0.252) patients, 12 seizure‐related injuries in 9/491 (2%, 95% CI 1.0–3.4%, p = 0.250) patients, and 5 episodes of status epilepticus in 4/491 (1%, 95% CI 0.3–2.1%, p = 0.120) patients.

Significance

Implementation of personalized safety measures in high‐risk patients resulted in a clinically relevant reduction of adverse events in the EMU. Safety protocols are a valid tool to reduce the occurrence of adverse events in EMUs.

Efficacy of naloxone in reducing postictal central respiratory dysfunction in patients with epilepsy: study protocol for a double-blind, randomized, placebo-controlled trial

Background

Generalized tonic-clonic seizures (GTCSs) are the main risk factor for sudden unexpected death in epilepsy (SUDEP). Experimental and clinical data strongly suggest that the majority of SUDEP results from a postictal respiratory dysfunction progressing to terminal apnea. Postictal apnea could partly derive from a seizure-induced massive release of endogenous opioids. The main objective of this study is to evaluate the efficacy of an opioid antagonist, naloxone, administered in the immediate aftermath of a GTCS, in reducing the severity of the postictal central respiratory dysfunction.

Methods/design

The Efficacy of Naloxone in Reducing Postictal Central Respiratory Dysfunction in Patients with Epilepsy (ENALEPSY) study is a multicenter, double-blind, randomized, placebo-controlled trial conducted in patients with drug-resistant focal epilepsy who are undergoing long-term video-electroencephalogram (EEG) monitoring (LTM) in an epilepsy monitoring unit (EMU). We plan to randomize 166 patients (1:1) to receive intravenous naloxone (0.4 mg) or placebo in the immediate aftermath of a GTCS. Because inclusion in the study needs to take place prior to the occurrence of the GTCS, and because such occurrence is observed in about one-fourth of patients undergoing LTM, we plan to include a maximum of 700 patients upon admission in the EMU. The primary endpoint will be the proportion of patients whose oxygen saturation is <90 % between 1 and 3 min after the end of a GTCS. Secondary outcomes will include the following: the proportion of patients who show postictal apnea, the occurrence and duration of postictal generalized EEG suppression, the total duration of the postictal coma, postictal pain, and the number of patients who have a second GTCS within 120 min after the intravenous injection.

Discussion

The demonstration of naloxone’s efficacy on the severity of postictal hypoxemia will have two primary consequences. First, naloxone would be the first and only therapeutic approach that could be delivered immediately to reverse postictal apnea. Second, demonstration that an opioid antagonist can effectively reduce postictal apnea would pave the way for an assessment of a preventive therapy for SUDEP targeting the same pathophysiological pathway using oral administration of naltrexone.

Trial registration

ClinicalTrials.gov identifier: NCT02332447. Registered on 5 January 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1653-1) contains supplementary material, which is available to authorized users.

Preoperative prediction of temporal lobe epilepsy surgery outcome

PURPOSE

There is controversy about relative contributions of ictal scalp video EEG recording (vEEG), routine scalp outpatient interictal EEG (rEEG), intracranial EEG (iEEG) and MRI for predicting seizure-free outcomes after temporal lobectomy. We reviewed NIH experience to determine contributions at specific time points as well as long-term predictive value of standard pre-surgical investigations.

METHODS

Raw data was obtained via retrospective chart review of 151 patients. After exclusions, 118 remained (median 5 years follow-up). MRI-proven mesial temporal sclerosis (MTSr) was considered a separate category for analysis. Logistic regression estimated odds ratios at 6-months, 1-year, and 2 years; proportional hazard models estimated long-term comparisons. Subset analysis of the proportional hazard model was performed including only patients with commonly encountered situations in each of the modalities, to maximize statistical inference.

RESULTS

Any MRI finding, MRI proven MTS, rEEG, vEEG and iEEG did not predict two-year seizure-free outcome. MTSr was predictive at six months (OR=2.894, p=0. 0466), as were MRI and MTSr at one year (OR=10.4231, p=0. 0144 and OR=3.576, p=0. 0091). Correcting for rEEG and MRI, vEEG failed to predict outcome at 6 months, 1year and 2 years. Proportional hazard analysis including all available follow-up failed to achieve significance for any modality. In the subset analysis of 83 patients with commonly encountered results, vEEG modestly predicted long-term seizure-free outcomes with a proportional hazard ratio of 1.936 (p=0.0304).

CONCLUSIONS

In this study, presurgical tools did not provide unambiguous long-term outcome predictions. Multicenter prospective studies are needed to determine optimal presurgical epilepsy evaluation.

Lateralization of mesial temporal lobe epilepsy with chronic ambulatory electrocorticography

OBJECTIVE

Patients with suspected mesial temporal lobe (MTL) epilepsy typically undergo inpatient video-electroencephalography (EEG) monitoring with scalp and/or intracranial electrodes for 1 to 2 weeks to localize and lateralize the seizure focus or foci. Chronic ambulatory electrocorticography (ECoG) in patients with MTL epilepsy may provide additional information about seizure lateralization. This analysis describes data obtained from chronic ambulatory ECoG in patients with suspected bilateral MTL epilepsy in order to assess the time required to determine the seizure lateralization and whether this information could influence treatment decisions.

METHODS

Ambulatory ECoG was reviewed in patients with suspected bilateral MTL epilepsy who were among a larger cohort with intractable epilepsy participating in a randomized controlled trial of responsive neurostimulation. Subjects were implanted with bilateral MTL leads and a cranially implanted neurostimulator programmed to detect abnormal interictal and ictal ECoG activity. ECoG data stored by the neurostimulator were reviewed to determine the lateralization of electrographic seizures and the interval of time until independent bilateral MTL electrographic seizures were recorded.

RESULTS

Eighty-two subjects were implanted with bilateral MTL leads and followed for 4.7 years on average (median 4.9 years). Independent bilateral MTL electrographic seizures were recorded in 84%. The average time to record bilateral electrographic seizures in the ambulatory setting was 41.6 days (median 13 days, range 0-376 days). Sixteen percent had only unilateral electrographic seizures after an average of 4.6 years of recording.

SIGNIFICANCE

About one third of the subjects implanted with bilateral MTL electrodes required >1 month of chronic ambulatory ECoG before the first contralateral MTL electrographic seizure was recorded. Some patients with suspected bilateral MTL seizures had only unilateral electrographic seizures. Chronic ambulatory ECoG in patients with suspected bilateral MTL seizures provides data in a naturalistic setting, may complement data from inpatient video-EEG monitoring, and can contribute to treatment decisions.

Research implications of the Institute of Medicine Report, Epilepsy Across the Spectrum: Promoting Health and Understanding

In March 2012 the Institute of Medicine (IOM) released the report, Epilepsy Across The Spectrum: Promoting Health and Understanding. This report examined the public health dimensions of the epilepsies with a focus on the following four areas: public health surveillance and data collection and integration; population and public health research; health policy, health care, and human services; and education for providers, people with epilepsy and their families, and the public. The report provided recommendations and research priorities for future work in the field of epilepsy that relate to increasing the power of data on epilepsy; prevention of epilepsy; improving health care for people with epilepsy; improving health professional education about epilepsy; improving quality of life for people with epilepsy; improving education about epilepsy for people with epilepsy and families; and raising public awareness about epilepsy. For this article, the authors selected one research priority from each of the major chapter themes in the IOM report: expanding and improving the quality of epidemiologic surveillance in epilepsy; developing improved interventions for people with epilepsy and depression; expanding early identification/screening for learning impairments in children with epilepsy; evaluating and promoting effective innovative teaching strategies; accelerating research on the identification of risk factors and interventions that increase employment and improve quality of life for people with epilepsy and their families; assessing the information needs of people with epilepsy and their families associated with epilepsy-related risks, specifically sudden unexpected death in epilepsy; and developing and conducting surveys to capture trends in knowledge, awareness, attitudes, and beliefs about epilepsy over time and in specific population subgroups. For each research priority selected, examples of research are provided that will advance the field of epilepsy and improve the lives of people with epilepsy. The IOM report has many other research priorities for researchers to consider developing to advance the field of epilepsy and better the lives of people with epilepsy.

A novel implanted device to wirelessly record and analyze continuous intracranial canine EEG

We present results from continuous intracranial electroencephalographic (iEEG) monitoring in 6 dogs with naturally occurring epilepsy, a disorder similar to the human condition in its clinical presentation, epidemiology, electrophysiology and response to therapy. Recordings were obtained using a novel implantable device wirelessly linked to an external, portable real-time processing unit. We demonstrate previously uncharacterized intracranial seizure onset patterns in these animals that are strikingly similar in appearance to human partial onset epilepsy. We propose: (1) canine epilepsy as an appropriate model for testing human antiepileptic devices and new approaches to epilepsy surgery, and (2) this new technology as a versatile platform for evaluating seizures and response to therapy in the natural, ambulatory setting.

Antiepileptic drugs and suicidality

The risk of suicide in patients with epilepsy is significantly higher than the general population. There are many hypotheses as to the reasons for this, but the potential role of anti-epileptic drugs (AEDs) in increasing suicidality has recently been brought into question. In 2008, the U.S. Food and Drug Administration (FDA) published a warning after a meta-analysis of data from all clinical trials involving AEDs found a suicidality risk of 0.43 per 1000 patients in active drug arms of these clinical trials compared to a rate in the placebo arm of 0.22. While an increased risk for individual AEDs was found in two, the FDA decided to issue a warning for the entire AED class. While this decision and the meta-analysis findings have been considered controversial, and have created concern that this stated risk may dissuade use of AEDs by patients who would benefit from them, it has led to increased awareness of the risk of suicidality and psychiatric co-morbidity in this patient group. In this article, the association of epilepsy and AEDs with psychiatric disease and suicidality are reviewed, perspective as to the significance and limitations of the FDA’s findings are discussed, and some options for suicidality screening and their potential utility in clinical care are evaluated.

Cardiac arrhythmias and ictal events within an epilepsy monitoring unit

The aim of this study was to determine the incidence and describe the factors influencing ictal cardiac arrhythmias in children with epilepsy. A 2-year review within a pediatric epilepsy monitoring unit revealed 2066 electrographically confirmed seizures in 139 patients. Demographic, seizure, and cardiac variables were collected for each patient. Fisher's exact test, Wilcoxon rank-sum test, and Spearman's rank correlation coefficient were used to identify significant differences and associations at the seizure and patient levels. In 244 seizures meeting inclusion criteria, ictal cardiac arrhythmias were seen in 45% of the seizures (40% of the patients). The most common arrhythmia was benign respiratory sinus arrhythmia (78% of seizures with arrhythmias, 70% of patients with arrhythmias). Potentially serious arrhythmias included irregular variable arrhythmias, and abnormal QRS intervals were seen in 12% of all the patients. In seizures with ictal arrhythmias, 64% occurred in male patients (P = 0.016) and 78% occurred in white patients (P = 0.013). This study estimates the incidence of ictal arrhythmias within the pediatric population that need further medical attention and management.