Mortality in epilepsy

Electrocardiographic Abnormalities and Mortality in Epilepsy Patients

Background and Objectives: People with epilepsy (PWE) have a 2–3 times higher mortality rate than the general population. Sudden unexpected death in epilepsy (SUDEP) comprises a significant proportion of premature deaths, whereas sudden cardiac death (SCD) is among the leading causes of sudden death in the general population. Cardiac pathologies are significantly more prevalent in PWE. Whether electrocardiographic (ECG) parameters are associated with remote death in PWE has yet to be elucidated. The study objective was to assess whether interictal ECG parameters are associated with mortality in the long-term. Materials and Methods: The study involved 471 epilepsy patients who were hospitalized after a bilateral tonic-clonic seizure(s). ECG parameters were obtained on the day of hospitalization (heart rate, PQ interval, QRS complex, QT interval, heart rate corrected QT interval (QTc), ST segment and T wave changes), as well as reported ECG abnormalities. Mortality data were obtained from the Latvian National Cause-of-Death database 3–11, mean 7.0 years after hospitalization. The association between the ECG parameters and the long-term clinical outcome were examined. Results: At the time of assessment, 75.4% of patients were alive and 24.6% were deceased. Short QTc interval (odds ratio (OR) 4.780; 95% confidence interval (CI) 1.668–13.698; p = 0.004) was associated with a remote death. After the exclusion of known comorbidities with high mortality rates, short QTc (OR 4.631) and ECG signs of left ventricular hypertrophy (OR 5.009) were associated with a remote death. Conclusions: The association between routine 12-lead rest ECG parameters—short QTc interval and a pattern of left ventricular hypertrophy—and remote death in epilepsy patients was found. To the best of our knowledge, this is the first study to associate rest ECG parameters with remote death in an epileptic population.

Epidemiology and long-term Turku outcome of childhood-onset epilepsy and mortality. Personal experiences. Part I

Introduction.Epidemiological studies on epilepsy were long based, with few exceptions, on hospital and institution patients with a subsequent bias toward more difficult cases and the reported prevalence and incidence rates were often obviously too low. Few data are available on the temporal changes in the incidence of epilepsy.

Aim.To study the prevalence and incidence in an unselected child population including all the children living either in the society or in the institution, temporal changes in the incidence and mortality through five decades.

Methods.The most important personal data were reviewed and compared with the relevant data of other investigators.

Results and discussion.The prevalence of epilepsy in our study was 3.2/1000, quite obviously true for the contemporary methodology and well comparable with 3.4–4.2/1000 of other relevant studies published about two decades later and using a more advanced methodology. Similarly, the incidence of 35/100 000, ascertained in two Finnish studies, was comparable with the relevant contemporary literature data. Another study of ours shows that, probably associated with the people “coming from the shadows” and an improved diagnostic methodology, the incidence of childhood epilepsy has increased and is now 60–70/100 000. However, the incidence of childhood epilepsy shows an obvious decreasing trend in the first two decades of the 2000s.

Conclusions.The incidence of childhood epilepsy, in all probability true for the contemporary methodology, was lower than it is now, but it now again shows a decreasing trend.

Cardiorespiratory abnormalities during epileptic seizures

Sudden unexpected death in epilepsy (SUDEP) is a leading cause of death in young and otherwise healthy patients with epilepsy, and sudden death is at least 20 times more common in epilepsy patients as compared to patients without epilepsy. A significant proportion of patients with epilepsy experience cardiac and respiratory complications during seizures. These cardiorespiratory complications are suspected to be a significant risk factor for SUDEP. Sleep physicians are increasingly involved in the care of epilepsy patients and a recognition of these changes in relation to seizures while a patient is under their care may improve their awareness of these potentially life-threatening complications that may occur during sleep studies. This paper details these cardiopulmonary changes that take place in relation to epileptic seizures and how these changes may relate to the occurrence of SUDEP.

Characteristics of seizure frequency among Malaysian children diagnosed with structural-metabolic epilepsy

Introduction:

Seizure-free patients or substantial reduction in seizure frequency are the most important outcome measures in the management of epilepsy. The study aimed to evaluate the patterns of seizure frequency and its relationship with demographics, clinical characteristics, and outcomes.

Materials and Methods:

A retrospective cohort study was conducted at the Pediatric Neurology Clinic, Hospital Pulau Pinang. Over a period of 6 months, the required data were extracted from the medical records using a pre-designed data collection form.

Results:

Seizure frequency showed no significant association with patient's demographics and clinical characteristic. However, significant reduction in seizure frequency from the baseline to the last follow-up visit was only seen in certain subgroups of patients including Malays, females, patients <4 years of age, patients with global developmental delay/intellectual disability, and patients with focal seizure. There was no significant association between seizure frequency and rate of adverse events. Polytherapy visits were associated with higher seizure frequency than monotherapy visits (27.97 ± 56.66, 10.94 ± 30.96 attack per month, respectively) (P < 0.001). There was a clear tendency to get antiepileptic drugs used at doses above the recommended range in polytherapy (8.4%) rather than in monotherapy (1.4%) visits (P < 0.001). A significant correlation was found between seizure frequency and number of visits per patient per year (r = 0.450, P < 0.001).

Conclusion:

Among children with structural–metabolic epilepsy, Malays, females, patients <4 years of age, patients with global developmental delay/intellectual disability and patients manifested with focal seizure are more responsive antiepileptic drug therapy than the other subgroups of patients.

Parasympathetic alteration during sub-clinical seizures

INTRODUCTION

Autonomic instability is considered a contributing factor in sudden unexpected death in epilepsy (SUDEP). The aim of this pilot study was to measure parasympathetic activity in sub-clinical seizures to investigate autonomic instability.

MATERIALS AND METHODS

A prospective study based on Video-electroencephalography (EEG)/electrocardiography (ECG)/oxygen saturation (SAO2) recordings was selected from patients having sub-clinical seizures during stage 3 or 4 sleep. We analysed R-R intervals in the ECG from 1-min prior to the electrographic onset to the end of sub-clinical seizures. Matched non-ictal R-R baseline measurements were selected from stages 3 or 4 sleep. R-R interval data were analysed using NeuroScope software providing a cardiac index of parasympathetic activity (CIPA). BioSignal short-term heart rate variability (HRV) software was used to analyse the same R-R interval data previously analysed using NeuroScope except that sub-clinical seizure data was embedded within 5-min epochs and compared to 5-min epochs of non-ictal measurements.

RESULTS

A total of 33 sub-clinical seizures were recorded from 11 patients comprising 19 generalised sub-clinical seizures (2 patients), 9 right temporal lobe sub-clinical seizures (5 patients) and 5 left temporal lobe sub-clinical seizures (4 patients) were compared to matched non-ictal measurements. Parasympathetic activity was clearly altered during total sub-clinical seizures in terms of the CIPA (p<0.001) and 5-min HRV high frequency (HF) % (p=0.026) measures. Generalised sub-clinical seizures resulted in increased cardiac parasympathetic activity whereas temporal lobe seizures were associated with a decrease in parasympathetic activity.

CONCLUSION

This pilot study indicates that parasympathetic changes occur during sub-clinical seizures. Generalised sub-clinical seizures may be associated with more autonomic instability compared to temporal lobe sub-clinical seizures.

A phenomenological model of seizure initiation suggests network structure may explain seizure frequency in idiopathic generalised epilepsy

We describe a phenomenological model of seizure initiation, consisting of a bistable switch between stable fixed point and stable limit-cycle attractors. We determine a quasi-analytic formula for the exit time problem for our model in the presence of noise. This formula--which we equate to seizure frequency--is then validated numerically, before we extend our study to explore the combined effects of noise and network structure on escape times. Here, we observe that weakly connected networks of 2, 3 and 4 nodes with equivalent first transitive components all have the same asymptotic escape times. We finally extend this work to larger networks, inferred from electroencephalographic recordings from 35 patients with idiopathic generalised epilepsies and 40 controls. Here, we find that network structure in patients correlates with smaller escape times relative to network structures from controls. These initial findings are suggestive that network structure may play an important role in seizure initiation and seizure frequency.

Forensic antiepileptic drug levels in autopsy cases of epilepsy

A 1-year retrospective coroner-based forensic examination of causes of death among persons with a history of epilepsy was conducted at the Allegheny County Coroner's Office to evaluate the phenomenon of sudden unexplained/unexpected death in epilepsy (SUDEP), a diagnosis of exclusion. All cases at the Coroner's Office from January 1, 2001 through December 31, 2001, were examined. Review of a total of 1200 autopsied deaths revealed 12 cases with a past medical history of seizure disorder on the death certificate, which listed seizure disorder as the immediate cause of death or contributory cause of the death. Of the 7 men with seizure disorders, 5 were categorized as definite SUDEP and 2 as possible SUDEP. Of the 5 women with seizure disorders, 2 were listed as definite SUDEP, 2 as possible, and 1 as non-SUDEP because the convulsive seizures developed from a grade II glial tumor. Postmortem findings were evaluated for 11 cases; 1 body was decomposed. Toxicological screens were carried out on blood, bile, urine, and eye fluid for all 12. Antiepileptic drug (AED) levels detected in postmortem toxicological analysis were examined. AED levels were determined in 7 cases. Four of 7 had subtherapeutic AED levels, 2 had therapeutic levels, and only 1 victim of SUDEP had levels above the therapeutic range. Five cases had no detectable AED levels. AED levels at autopsy were either absent or subtherapeutic in 9 of 10 SUDEP cases, findings consistent with the likelihood of poor AED compliance. Subtherapeutic levels of AEDs may be a risk factor for SUDEP that could contribute to increased interictal and/or ictal epileptiform activity with associated autonomic dysfunction leading to disturbance of heart rate, heart rhythm, and/or blood pressure.

Effects of ethyl loflazepate on refractory epilepsy in children

We evaluated the safety and efficacy of ethyl loflazepate in children with epilepsy. The study group comprised 21 outpatients (4 by generalized, 17 by localization-related) aged between 9 months and 17 years. Ethyl loflazepate was administered at a dose of 0.015 mg/kg/day twice daily. The final mean dose was 1.35 mg/day. The mean number of prior antiepileptic drugs was 5.7. The entire treatment period was more than 24 months after ethyl loflazepate administration. Six children (28.6%) became seizure-free for the entire study 6 months after administration, 11 (52.4%) had a seizure reduction of more than 50% for over entire 24 months. The mean number of co-medications was 2.4. Adverse events occurred in only 1 patient. Responders, defined as reduction of ≥50% in seizure frequency, included 2/2 of patients with West syndrome and 15/17 (88.2%) with localization-related epilepsy. Ethyl loflazepate represents an important addition to the treatments available for refractory epilepsies in children.

Characterising the dynamics of EEG waveforms as the path through parameter space of a neural mass model: application to epilepsy seizure evolution

In this paper we propose that the dynamic evolution of EEG activity during epileptic seizures may be characterised as a path through parameter space of a neural mass model, reflecting gradual changes in underlying physiological mechanisms. Previous theoretical studies have shown how boundaries in parameter space of the model (so-called bifurcations) correspond to transitions in EEG waveforms between apparently normal, spike and wave and subsequently poly-spike and wave activity. In the present manuscript, we develop a multi-objective genetic algorithm that can estimate parameters of an underlying model from clinical data recordings. A standard approach to this problem is to transform both clinical data and model output into the frequency domain and then choose parameters that minimise the difference in their respective power spectra. Instead in the present manuscript, we estimate parameters in the time domain, their choice being determined according to the best fit obtained between the model output and specific features of the observed EEG waveform. This results in an approximate path through the bifurcation plane of the model obtained from clinical data. We present comparisons of such paths through parameter space from separate seizures from an individual subject, as well as between different subjects. Differences in the path reflect subtleties of variation in the dynamics of EEG, which at present appear indistinguishable using standard clinical techniques.

Identifying epilepsy surgery candidates in the outpatient clinic

Epilepsy is the most prevalent disabling neurological disorder across the life span, and is not controlled by medications in more than one-third of patients. Epilepsy surgery is an accepted treatment, with guidelines supporting utilization in patients with recurrent temporal lobe seizures after two or more trials of antiepileptic medications. Unfortunately, the average delay in presurgical evaluation of appropriate candidates is more than 20 years, and this delay has not improved in recent decades. This offers the international neurological community the opportunity to improve disability, mortality, and quality of life by more effective application of epilepsy surgery and earlier identification of potential candidates. Optimal use of MRI and video/EEG monitoring should allow cost-effective screening of persons with recurrent seizures prior to more detailed presurgical evaluation when indicated.

Non-invasive assessment of cardioregulatory autonomic functions in children with epilepsy

OBJECTIVES

We aimed to evaluate the interictal cardiovascular autonomic functions in pediatric patients with idiopathic epilepsy, both partial and generalized.

MATERIALS AND METHODS

The study included 25 patients with idiopathic epilepsy and 50 control subjects. Patients underwent five standardized clinical cardiovascular reflex autonomic tests [resting heart rate (HR), HR response to deep breathing and to Valsalva maneuver, the 30:15 ratio of HR response to standing, and blood pressure response to standing], as well as a 12 lead surface electrocardiogram. Heart rate variability (HRV) was tested via 24-h Holter monitoring and the time domain parameters (SDNN, PNN50, rMSDD) were assessed. Excretion of vanillyl mandelic acid and metanephrine was measured in 24-h urine collection.

RESULTS

Clinical reflex autonomic tests showed mild dysfunction in 8%, moderate dysfunction in 44% and severe dysfunction in 4% of patients. The HRV parameter, SDNN, was reduced in all age groups, while rMSDD and PNN50 were reduced only in the older age group. Metanephrine levels were significantly reduced in the patients group. Patients with uncontrolled epilepsy had a significantly higher frequency of autonomic dysfunction as assessed by clinical scoring.

CONCLUSION

Cardiac autonomic dysfunction is not uncommon in pediatric patients with epilepsy. Altered cardiovascular regulation seems to be related to the epilepsy itself rather than to the characteristics of the disorder.

Respiratory pattern in a rat model of epilepsy

PURPOSE

Apnea is known to occur during seizures, but systematic studies of ictal respiratory changes in adults are few. Data regarding respiratory pattern defects during interictal periods also are scarce. Here we sought to generate information with regard to the interictal period in animals with pilocarpine-induced epilepsy.

METHODS

Twelve rats (six chronically epileptic animals and six controls) were anesthetized, given tracheotomies, and subjected to hyperventilation or hypoventilation conditions. Breathing movements caused changes in thoracic volume and forced air to flow tidally through a pneumotachograph. This flow was measured by using a differential pressure transducer, passed through a polygraph, and from this to a computer with custom software that derived ventilation (VE), tidal volume (VT), inspiratory time (TI), expiratory time (TE), breathing frequency (f), and mean inspiratory flow (VT/TI) on a breath-by-breath basis.

RESULTS

The hyperventilation maneuver caused a decrease in spontaneous ventilation in pilocarpine-treated and control rats. Although VE had a similar decrease in both groups, in the epileptic group, the decrease in VE was due to a significant (p < 0.05) increase in TE peak in relation to that of the control animals. The hypoventilation maneuver led to an increase in the arterial Paco2, followed by an increase in VE. In the epileptic group, the increase in VE was mediated by a significant (p < 0.05) decrease in TE peak compared with the control group. Systemic application of KCN, to evaluate the effects of peripheral chemoreception activation on ventilation, led to a similar increase in VE for both groups.

CONCLUSIONS

The data indicate that pilocarpine-treated animals have an altered ability to react to (or compensate for) blood gas changes with changes in ventilation and suggest that it is centrally determined. We speculate on the possible relation of the current findings on treating different epilepsy-associated conditions.

Epilepsy and injury mortality in Sweden--the importance of changes in coding practice

We analysed national mortality trends of injuries and poisoning in patients with epilepsy to establish the importance of changes in coding practice. Patients where epilepsy was a syndrome, either as an underlying or contributing cause-of-death at any time of life, throughout Sweden during 1975-1995 were included. All conditions mentioned on each death certificate were examined, and epilepsy and injury diagnoses were separated according to underlying, contributing or multiple cause-of-death. Annual mortality rates, case-fatality rates, and linear regression coefficients were computed. The most common underlying cause-of-death (UCD) was diseases of the circulatory system (34.4%) followed by epilepsy (31.7%). Injury and poisoning were coded as UCDs for 5.8% of the patients. Injury and poisoning as a contributory cause-of-death increased significantly, but not as an underlying cause during the study period. The proportion of each diagnostic group as an underlying cause decreased by 35% for epilepsy and 18% for injury from 1981 and onwards. These changes should be interpreted with caution since changes of coding practice are more likely to be the cause of these apparent changes. The most frequent specific external causes of injury deaths in epileptic patients were falls and drowning. Intracranial fatal injuries in connection with fall accidents predominated, especially among elderly persons. Deaths related to accidental poisoning were caused by the toxic effect of non-medicinal substances. Cause-of-death statistics from different countries must be interpreted with caution when making international comparisons. Both underlying and contributing cause-of-death statistics should be considered in analyses of mortality trends.

Mortality among epilepsy patients attending a tertiary referral center in a developing country

Epilepsy is associated with excess mortality of two to three times in developed countries. Precise epidemiological data on mortality and cause of death are not available from India or most other developing countries. This study was carried out to estimate the mortality rates and to identify the demographic and clinical characteristics associated with mortality in a hospital based cohort of epilepsy patients. A cohort of patients enrolled in the epilepsy clinic in 1985 was followed up till 1997 (12 years). The mortality rate, demographic and clinical correlate of mortality were analysed for 246 patients (men 161, women 85) who had complete data. Cause of death was not examined in this study. Eighteen (men 15, women 3) of the 246 patients (7.3%) had died during the follow up period of 12 years. The crude death rate for the state of Kerala for the year 1990 (mid period of the study) was 5.9 per thousand population. The demographic and clinical characteristics of those who died (corresponding figures for survivors are given in brackets) were as follows: mean age 33.6 years (22.8 years), presence of abnormal neurological examination 38.9% (15.4%), mental retardation 33.3% (12.8%), abnormal CT scan 38% (21.5%). Regarding the seizure frequency at the time of enrollment and eventual mortality, there were no deaths among patients who had an Engel's seizure score of less than or equal to 4 (no seizures or nocturnal seizures only). The mortality was 5% for an Engel's score of 5 or 6 and 11% for an Engel's score greater than 6. Within the group with epilepsy, higher seizure frequency at the time of initial evaluation was associated with excess mortality. Abnormality on neurological examination, older age group and male sex were other factors that correlated with excess mortality.

The epidemiology of epilepsy: the size of the problem

The prevalence of epilepsy is generally taken as between 5 and 10 cases per 1000 persons, and the overall incidence as about 50 cases per 100 000 persons. The rates are dependent on case ascertainment and on definitions used. The prognosis depends on many factors, including the number of seizures at presentation, the seizure type and the use of anti-epileptic drugs. Epilepsy carries an excess mortality; the cause of death can be unrelated to epilepsy, related to the underlying disease causing epilepsy, or related to epilepsy itself.

Assessing risk to benefit ratio in antiepileptic drug therapy

Assessment of risk to benefit ratio in patients with epilepsy is crucial in determining the need for treatment, the choice of drugs and the use of monitoring tools such as laboratory tests and other investigations. Active epilepsy per se carries significant risks in terms of increased mortality, susceptibility to psychopathology and physical injury, and reduced quality of life as a result of restricted lifestyle, stigma and prejudice. By preventing the occurrence of seizures, antiepileptic drugs (AEDs) attenuate or eliminate altogether seizure-related risks, but other risks may arise due to the side effects of the drugs, all of which have a relatively narrow therapeutic index. While there are no major differences in the degree of efficacy between AEDs which are effective in any given seizure type, side effect profiles differ considerably from one agent to another and represent a major factor in determining choice of treatment. Assessment of risk to benefit ratio should also take into consideration patient-specific factors such as type and severity of the epilepsy, age, sex, childbearing potential, medical and drug history, associated disease, use of concomitant medication (including the contraceptive pill) and the prospected patient's compliance. In some benign epilepsy syndromes, such as idiopathic partial epilepsy with centro-temporal spikes, the risk of side effects from AEDs may outweigh potential benefits in terms of seizure control, and treatment is generally not indicated. At the opposite end of the spectrum, the serious morbidity and mortality associated with severe epileptic encephalopathies, such as the Lennox-Gastaut syndrome, justifies aggressive treatment even with drugs associated with a relatively high risk of life threatening side effects such as felbamate. The present article will provide an overview of specific risks associated with epilepsy and with the various drugs used for its treatment, and will attempt to evaluate the complex balance between these risks and therapeutic benefits in different categories of patients.

Short-term mortality after a first epileptic seizure: a population-based study

PURPOSE

To determine the short-term mortality in a prospective incidence cohort of patients included after any kind of first afebrile epileptic seizure (i.e., provoked and unprovoked).

METHODS

Information on death occurring within the first year of follow-up was collected in a cohort of 804 patients with a first seizure between March 1, 1984, and February 28, 1985, in southwest France. The variables analyzed were the etiology of seizure, cause of death, interval between seizure and death, and age of patients.

RESULTS

By the end of the 1-year follow-up, there were 149 deaths among these patients as compared with 16 expected deaths [standardized mortality ratio (SMR), 9.3; 95% confidence interval (CI), 7.9-10.9]. There were no deaths in patients with idiopathic seizures. Patients with cryptogenic seizures had slightly increased mortality (SMR, 1.6; 95% CI, 0.4-4.1). Mortality was increased for patients with remote symptomatic seizures (SMR, 6.5; 95% CI, 3.8-10.5), provoked seizures (SMR, 10.1; 95% CI, 8.1-12.4), and seizures due to a progressive neurologic condition (SMR, 19.8; 95% CI, 14.0-27.3). Causes of death were underlying pathology (64%), unrelated condition (20%), unknown cause (9%), seizure-related death (6%), and one suicide.

CONCLUSIONS

Early mortality clearly differed according to the etiology of the first seizure. The highest mortality was associated with provoked seizures and with seizures caused by progressive central nervous system disorders. Patients died far more often from underlying or unrelated conditions than from seizures.

Status epilepticus in children with newly diagnosed epilepsy

Status epilepticus (SE) constitutes a neurological emergency and may be of prognostic value in individuals with epilepsy. Little is known about the associations between other prognostic factors in epilepsy and the occurrence of SE. The following study examines associations between clinical characteristics of children with newly diagnosed epilepsy and the occurrence of SE when epilepsy is first diagnosed. Children were recruited prospectively from the practices of physicians throughout Connecticut. Information was collected via standardized interviews with parents and review of pertinent records. Analyses were performed for any SE, unprovoked SE only, and previous provoked SE. Of 613 children, 56 (9.1%) had one or more episodes of SE by the time the diagnosis of epilepsy was established. Factors correlated with SE during an unprovoked seizure were partial seizures and previous craniotomy. For SE during a provoked seizure, correlates were primarily young age at onset of epilepsy and nonidiopathic epilepsy syndrome. To date, subsequent SE has occurred in 4.3% of children without and in 19.6% of those with SE at diagnosis. By the time epilepsy is first diagnosed in children, SE has already occurred in a substantial minority. It is correlated with specific clinical characteristics in the children, which differ depending on whether the SE was provoked or unprovoked. SE has a high risk of recurring.