Arrhythmogenic seizures

A clinical evaluation of a novel algorithm in the reliable detection of epileptic seizures

PURPOSE

Undetected and prolonged epileptic seizures can result in hypoxic brain damage or death and occur most often when the victim is in bed alone or unsupervised. Sudden unexpected death in epilepsy may not always be preventable but it is believed that timely assistance with rescue medication and body re-positioning may overcome respiratory compromise in some cases. A novel algorithm based on a real time moving 9 s epoch, calculating 25 % percentage heart rate change and/or an oxygen saturation trigger level of <85 % was developed using photoplethysmography and incorporated into a prototype data storage device.

METHODS

The algorithm was clinically evaluated in this multicentre trial in the detection of clinically significant epileptic seizures. A range of epileptic seizures and normal physiological events were recorded and classified by reference standard EEG Videotelemetry and time-synchronised event data recorded by the prototype device incorporating the pre-specified cut-off points prospectively and retrospective analysis of all events.

RESULTS

119 participants who were attending electroencephalographic (EEG) videotelemetry as part of their clinical management of their epilepsy consented to take part in the trial. 683 epileptic seizures (77 clinically significant seizures) and 2648 normal physiological events were captured. When using pre-specified cut-off point 25 % heart rate change and/or oxygen desaturation <85 % on the basis of one/other, the device showed a sensitivity of 87 % for detecting clinically significant seizures. False Alarm Rate 4.5 (24 h FAR), detection latency of 58 s using heart rate percentage change.

CONCLUSIONS

The results indicate that the novel algorithm can be used in detecting clinically significant seizures.

Arrhythmogenic epilepsy and pacing need: A matter of controversy

There is increasing awareness among the cardiology community regarding ictal bradyarrhythmias as a cause of loss of consciousness. A high degree of suspicion is necessary when diagnosing ictal bradyarrhythmias, and delay in diagnosing this condition may lead to morbidity associated with falls and trauma. Ictal bradyarrhythmias have also been suggested to be associated with sudden unexplained death in epilepsy, although evidence related to this association is limited. There is no guideline-directed therapy for symptomatic ictal bradyarrhythmias due to a lack of randomized, controlled trials. Cardiac pacemaker therapy is commonly used for these patients; however, currently, there is no universal agreement on the pacing indications for these patients. In this review, we focus on the pathophysiology and clinical presentation of ictal bradyarrhythmias and then discuss the pacing need based on the available literature data.

Semiologic, electroencephalographic and electrocardiographic correlates of seizure-like manifestations caused by cardiac asystole

PURPOSE

Cardiac asystole is known to cause clinical manifestations mimicking seizures. The recognition of this uncommon phenomenon is important to expedite appropriate clinical intervention and avoid unnecessary morbidity as well as potential mortality.

METHODS

We retrospectively reviewed video-electroencephalographic (EEG) records from January 2008 to December 2013 for relevant cases.

RESULTS

We identified four patients who experienced nine events of asystole accompanied by seizure-like activity captured on video-EEG. None had evidence of epilepsy on video-EEG. Semiological features of captured clinical events included aura, automatisms, generalized tonic activity and focal as well as generalized myoclonus. No patient had generalized tonic-clonic seizures. A peculiar rapid breathing pattern was seen preceding the onset of asystole. General pallor was observed during asystole, followed by flushing on recovery. Seizure-like semiology was observed in three stages; pre-asystole, during asystole and after resumption of cardiac rhythm. The EEG demonstrated generalized slowing followed by generalized suppression during asystole and generalized slowing again on resumption of sinus rhythm ("slow-flat-slow" pattern). All patients had dual-chamber pacemakers implanted. On follow-up, they have remained symptom-free without antiepileptic medications.

CONCLUSIONS

Cardiac asystole can be associated with features closely mimicking seizures. Recurrent episodes of cardiac asystole can be stereotypical in a given patient. There are some diagnostic clues in semiology.

Autonomic alterations and cardiac changes in epilepsy

Studies with heart rate variability have revealed interictal autonomic alterations in patients with epilepsy. In addition, epilepsy is frequently associated with ictal tachycardia or bradycardia, which sometimes precedes the onset of seizures. Ictal tachycardia is sometimes associated with electrocardiography (ECG) morphologic changes and ictal bradycardia often progresses to asystole. Such cardiac manifestations of seizures have been hypothesized as possible causes for sudden unexplained death in epilepsy (SUPEP). The present review relates to interictal and ictal cardiac manifestations of epilepsy with focus on heart rate, heart rate variability, and ECG changes. Aspects of the supporting mechanisms are discussed and attention is drawn to the interaction between central and peripheral effects, interictal autonomic conditions, ictal autonomic discharges, and administration of antiepileptic drugs in shaping the ictal cardiac changes. Because these interactions are complex and not totally understood, closer surveillance of patients and more experimental work is necessary to elucidate the mechanistic support of autonomic and cardiac changes in epilepsy, and to design better strategies to avoid their undesirable effects. It is also suggested that some of these changes could be used as predictors or markers for the onset of seizures.

Recurrent unexplained syncope may have a cerebral origin: report of 10 cases of arrhythmogenic epilepsy

BACKGROUND

Despite thorough investigation, approximately 15-20% of syncope cases remain unexplained. An underrecognized cause of syncope may occur when partial epileptic discharges profoundly disrupt normal cardiac rhythm, including cardiac asystole, the so-called arrhythmogenic epilepsy (AE).

AIM

To report initial results of observations of AE in patients with recurrent, unexplained, traumatic and/or convulsive syncope.

METHODS

Ten patients aged 49+/-20 years (median 49.5 years; nine women) underwent complete cardiological (including ambulatory Holter electrocardiogram (ECG), echocardiography and head-up tilt test [plus electrophysiology in four patients]) and neurological (including standard electroencephalogram [EEG], computed tomography [CT] and magnetic resonance imaging scan [MRI]) assessments.

RESULTS

After initial evaluation, neurocardiogenic syncope was suspected in six patients with tilt-induced hypotension+/-bradycardia. Further evaluation (prolonged inpatient video-EEG/ECG monitoring) was undertaken because of non-diagnostic syncope or uncertainty about the diagnosis of neurocardiogenic syncope. While monitored in the neurophysiology lab, a syncopal episode similar to the spontaneous episodes recurred in all 10 patients. Cardiac asystole preceded by partial seizure of temporal onset was documented in nine patients; a second-degree atrioventricular (AV) block with a cardiac rhythm of 30 beats per minute preceded by partial seizure of temporal onset was noted in one patient. Eight patients were treated successfully with antiepileptic drugs; two were refractory to antiepileptic therapy and required pacemaker implantation. No patient had recurrent syncope during a median follow-up of 102.5 months (mean 82.2+/-42; range 16-128 months).

CONCLUSIONS

In patients with recurrent, unexplained, traumatic and/or convulsive syncope, AE should be considered as a possible aetiology.

The ictal bradycardia syndrome: localization and lateralization

PURPOSE

Previous studies have established the importance of the insular cortex and temporal lobe in cardiovascular autonomic modulation. Some investigators, based on the results of cortical stimulation response, functional imaging, EEG recordings of seizures, and lesional studies, have suggested that cardiac sympathetic and parasympathetic function may be lateralized, with sympathetic representation lateralized to the right insula, and parasympathetic, to the left. These studies have suggested that ictal bradycardia is most commonly a manifestation of activation of the left temporal and insular cortex. However, the evidence for this is inconsistent. We sought to assess critically the predictable value of ictal bradycardia for seizure localization and lateralization.

METHODS

In this study, we reviewed the localization of seizure activity in 13 consecutive patients with ictal bradycardia diagnosed during prolonged video-EEG monitoring at Mayo Clinic Rochester. The localization of electrographic seizure activity at seizure onset and bradycardia onset was identified in all patients. In addition, we performed a comprehensive review of the ictal bradycardia literature focusing on localization of seizure activity in ictal bradycardia cases.

RESULTS

All occurrences of ictal bradycardia in the 13 identified patients were associated with temporal lobe-onset seizures. However, no consistent lateralization of seizure activity was found at onset of seizure activity or at onset of bradycardia in this population. Seizure activity was bilateral at bradycardia onset in nine of 13 patients. The results from the literature review also showed that a predominance of patients had bilateral activity at bradycardia onset; however, more of the ictal bradycardia cases from the literature had left hemispheric localization of seizure onset.

CONCLUSIONS

Ictal bradycardia most often occurs in association with bilateral hemispheric seizure activity and is not a consistent lateralizing sign in localizing seizure onset. Our data do not support the existence of a strictly unilateral parasympathetic cardiomotor representation in the left hemisphere, as has been suggested.

Does epilepsy surgery lower the mortality of drug-resistant epilepsy?

Drug-resistant epilepsy has proved to be associated with an increased standardized mortality ratio (SMR), primarily due to seizure-related fatalities including sudden unexpected death (SUDEP). Recent studies have suggested that the surgical cure of temporal lobe epilepsy (TLE) was likely to normalize the SMR of patients suffering from refractory TLE. However, these studies raise a number of methodological issues, which have not always been fully addressed. Some conclusions have relied on previously reported data, indicating a SMR of approximately 5, and a SUDEP incidence of 9/1000 patient-years in drug-resistant epilepsy. In fact, as shown in this review, SMR varied considerably, from 2 to 16, in the various series of patients with refractory epilepsy, whereas the average SUDEP incidence in the same populations was calculated at 3.7/1000 patient-years. Other conclusions were based on the comparison of either surgically and medically treated patients, or cured and non-cured operated patients. In both situations, the two groups included a different proportion of excellent and poor surgical candidates. The biological differences that distinguish these two populations might explain part of the differences observed in their mortality rate, regardless of the effect of surgery. In particular, temporal-plus epilepsies involving the insula, the frontal orbital, or the frontal operculum region, might favour ictal arrhythmias, central apnoea and secondary generalization, which in turn would increase the risk of SUDEP. Future studies are thus warranted to specifically address these issues.

Sudden death in a 35-year-old man with occult malformation of the brain and aseptic meningitis

A 35-year-old man was found dead by his wife. He was reported to have had symptoms of a common cold the week preceding his death. The medicolegal autopsy yielded signs of central dysregulation (ectasia of the urinary bladder and rectum, dystelectasis of the lungs) together with marked brain edema and fresh bite marks on the tongue. The cause of death was presumed to be lethal epileptic seizure. Neuropathologic examination revealed neuronal nodular heterotopia as well as discrete lymphocytic meningitis (aseptic meningitis). The death was most probably caused by the combination of the meningitis with the occult malformation, leading to a lowered seizure threshold and subsequent lethal seizure. The morphologic findings of this case are presented, and the probable mechanisms of death are discussed.

Cardiac asystole in epilepsy: clinical and neurophysiologic features

PURPOSE

Cardiac asystole provoked by epileptic seizures is a rare but important complication in epilepsy and is supposed to be relevant to the pathogenesis of sudden unexplained death in epilepsy (SUDEP). We sought to determine the frequency of this complication in a population of patients with medically intractable epilepsy and to analyze the correlation between EEG, electrocardiogram (ECG), and clinical features obtained from long-term video-EEG monitoring.

METHODS

Retrospective analysis of the clinical records of hospitalized patients from May 1992 to June 2001 who underwent long-term video-/EEG monitoring.

RESULTS

Of a total of 1,244 patients, five patients had cardiac asystole in the course of ictal events. In these patients, 11 asystolic events, between 4 and 60 s long in a total of 19 seizures, were registered. All seizures had a focal origin with simple partial seizures (n = 13), complex partial seizures (n = 4), and secondarily generalized seizures (n = 2). One patient showed the longest asystole ever reported (60 s) because of a seizure. Cardiac asystole occurred in two patients with left-sided temporal lobe epilepsy (TLE) and in three patients with frontal lobe epilepsy (FLE; two left-sided, one bifrontal). Two patients reported previous cardiac disease, but only one had a pathologic ECG by the time of admission. Two patients had a simultaneous central ictal apnea during the asystole. None of the patients had ongoing deficits due to the asystole.

CONCLUSIONS

These findings confirm that seizure-induced asystole is a rare complication. The event appeared only in focal epilepsies (frontal and temporal) with a lateralization to the left side. A newly diagnosed or known cardiac disorder could be a risk factor for ictal asystole. Abnormally long postictal periods with altered consciousness might point to reduced cerebral perfusion during the event because of ictal asystole. Central ictal apnea could be a frequent associated phenomenon.

Ictal bradycardia in a young child with focal cortical dysplasia in the right insular cortex

We report on a three and a half year old child with episodic sinus bradycardia during habitual seizures and prolonged interictal discharges due to focal cortical dysplasia in the anterior 2/3 of the insula and the inferior frontal cortex. Seizure-induced bradycardia is rarely reported in children. Bradycardia is suspected to be related to sudden death, a rare complication of a chronic seizure disorder. Several well-documented cases in adult patients reveal a high incidence of temporal epilepsy, but MRI and PET studies in healthy subjects suggest a major role of the insular cortex, especially the right, in cardiac regulation. Our finding underlines the predominance of the right insula in cardiac control, which already seems to be present in children.

Atrio-ventricular block: a possible explanation of sudden unexpected death in epilepsy

INTRODUCTION

This is the third case report describing the occurrence of total atrio-ventricular (AV)-block as a life threatening cardiac arrhythmia complicating epileptic seizures.

CASE REPORT

A 56-year-old right-handed man was admitted to our hospital for surgical assessment of his medically intractable epilepsy. During the hospitalization he was enrolled in a study investigating cardiac complication of epileptic seizures as the possible cause of sudden unexplained death among epileptics.

DISCUSSION

To the best of our knowledge, we are the first to employ simultaneous video-electroencephalogram-, Holter- and pulse oximetry-recordings of our patients in the description of this complication. These recordings allowed us to discuss the evidence and consequences of this particular cardiac abnormality as an explanation of sudden unexplained death in epileptic seizures, especially those of temporal origin.

Sudden unexplained death in children with epilepsy

BACKGROUND

Sudden unexplained death is a significant cause of mortality in people with epilepsy. Risk factors that have been identified include male sex, poor compliance with medications, and antiepileptic drug (AED) polypharmacy. However, these may not apply to the pediatric population in which the causes of epilepsy differ from the adult population. Therefore, risk factors for sudden unexplained death in epilepsy (SUDEP) in children must be evaluated independently from those in the adult population.

METHODS

Cases of SUDEP in children less than 18 years of age occurring over a 10-year period in the province of Ontario, Canada, were identified. Records were reviewed for demographic and clinical features and neuropathology findings.

RESULTS

Twenty-seven cases of SUDEP in children were identified. Sixty-three percent were male. Age at death ranged from 8 months to 15 years. Fourteen children had symptomatic epilepsy (52%), five had cryptogenic epilepsy (18%), and eight had idiopathic epilepsy (30%). Twelve children were treated with one AED (46%), 10 were on two AED (38%), and three were on three AED (12%). At the time of death, seven children had one serum AED concentration below the therapeutic range (35%) and 12 children had AED levels within the therapeutic range (60%).

CONCLUSIONS

This case series represents the largest series of sudden unexplained death in children with epilepsy. At least two previously described risk factors for SUDEP in adults, low serum AED levels at time of death and AED polytherapy, do not appear to be significant in children.

Idiopathic cardiac asystole presenting as an intractable adult onset partial seizure disorder

Asystole can occur during partial seizures. Conversely, asystole may produce clinical features associated semiologically with partial or secondarily generalized tonic--clonic seizures. Management is so profoundly different that accurate diagnosis is critical. We performed simultaneous scalp video electroencephalographic (EEG) and electrocardiographic (ECG) recordings in three patients who presented with an intractable seizure disorder. Habitual events were captured and reviewed. These revealed similar clinical features and temporal association with the ECG and EEG findings. Idiopathic asystole was detected as the cause in all three. All underwent emergency cardiac pacemaker implantation with resultant cessation of their paroxysmal episodes. If this diagnostic study had been delayed or not performed, all of our patients could have presented as sudden unexpected death in epilepsy (SUDEP). Early video-EEG and ECG monitoring is essential in adults with intractable seizure disorders.

[Bradycardia as an epileptic manifestation in temporal epilepsy: report of a case]

We describe a patient who had cardiac arrhythmia as epileptic manifestation. In a 34-year-old woman who had many episodes of loss of consciousness, the simultaneous ECG and video-EEG monitoring recorded bradycardia with a short episode of asystole (4 seconds) and left temporal rhythmic theta activity on EEG. MRI showed a small mass lesion in the left parahippocampal gyrus. Alterations in cardiac rhythm have been reported in epileptic seizures and tachycardia is the most common finding associated with them; bradyarrhythmia during seizures was uncommon. Many interconnections among insular cortex, limbic system and hypothalamus, may be responsible for vegetative manifestations in temporal lobe epilepsy.

Postictal Depression following Subtle Seizures

We describe a woman with stereotypic recurrent episodes of severe depression with suicidal ideation that follow series of simple partial seizures. Her seizures were not clinically recognized for many years. When her seizures are effectively treated with antiepileptic drug therapy, her depressive episodes remit.

Oxygen desaturations triggered by partial seizures: implications for cardiopulmonary instability in epilepsy

PURPOSE

The occurrence of hypoxemia in adults with partial seizures has not been systematically explored. Our aim was to study in detail the temporal dynamics of this specific type of ictal-associated hypoxemia.

METHODS

During long-term video/EEG monitoring (LTM), patients underwent monitoring of oxygen saturation using a digital Spo2 (pulse oximeter) transducer. Six patients (nine seizures) were identified with oxygen desaturations after the onset of partial seizure activity.

RESULTS

Complex partial seizures originated from both left and right temporal lobes. Mean seizure duration (+/-SD) was 73 +/- 18 s. Mean Spo2 desaturation duration was 76 +/- 19 s. The onset of oxygen desaturation followed seizure onset with a mean delay of 43 +/- 16 s. Mean (+/-SD) Spo2 nadir was 83 +/- 5% (range, 77-91%), occurring an average of 35 +/- 12 s after the onset of the desaturation. One seizure was associated with prolonged and recurrent Spo2 desaturations.

CONCLUSIONS

Partial seizures may be associated with prominent oxygen desaturations. The comparable duration of each seizure and its subsequent desaturation suggests a close mechanistic (possibly causal) relation. Spo2 monitoring provides an added means for seizure detection that may increase LTM yield. These observations also raise the possibility that ictal ventilatory dysfunction could play a role in certain cases of sudden unexpected death in epilepsy in adults with partial seizures.

EKG abnormalities during partial seizures in refractory epilepsy

PURPOSE

This study assessed the frequency and character of ictal cardiac rhythm and conduction abnormalities in intractable epilepsy. Sudden unexpected death in epilepsy (SUDEP) is a major cause of excess mortality in people with refractory epilepsy, and cardiac arrhythmias during seizures may be responsible. The frequency of cardiac abnormalities during seizures in patients with refractory epilepsy must be determined.

METHODS

Fifty-one seizures in 43 patients with intractable partial epilepsy were analyzed prospectively from CCTV-EEG monitoring with one ECG channel. Arrhythmias, repolarization abnormalities, and PR and QTc intervals were determined for preictal (3 min), ictal, and postictal (3 min) periods for one or more seizures per patient. Parametric statistics were used for continuous variables, and nonparametric statistics were used for categoric variables.

RESULTS

Of the patients, 39% had one or more abnormalities of rhythm and/or repolarization during or immediately after seizures. Abnormalities included asystole (one), atrial fibrillation (one), marked or moderate sinus arrhythmia (six), supraventricular tachycardia (one), atrial premature depolarizations (APDs; eight), ventricular premature depolarizations (VPDs; two), and bundle-branch block (three). Mean seizure duration was longer in patients with abnormalities than in those without (204 vs. 71 s; p < 0.001). Generalized tonic-clonic seizures were also associated with increased occurrence of ictal ECG abnormalities (p = 0.006) as compared with complex partial seizures. There were no clinically significant differences in mean preictal and ictal/postictal PR and QTc intervals.

CONCLUSIONS

Cardiac rhythm and conduction abnormalities are common during seizures, particularly if they are prolonged or generalized, in intractable epilepsy. These abnormalities may contribute to SUDEP.

Amygdala sclerosis in sudden and unexpected death in epilepsy

Sclerosis of the amygdala is a not uncommon finding in patients with chronic epilepsy. The amygdala has efferent connections, via the central nuclei, to cardioregulatory centres in the medulla. Experimental studies have suggested that damage to the central nucleus may be of functional significance in patients with sudden and unexpected death in epilepsy (SUDEP) in particular with regard to their susceptibility to cardiac arrhythmias. We investigated this possibility by carrying out a quantitative immunohistochemical analysis of the patterns of neuronal loss and gliosis in three amygdala subnuclei (central, basal and lateral) in post mortem material from 15 SUDEP cases and seven normal controls. We identified significant neuronal loss in the medial division of the lateral amygdaloid nucleus in SUDEP cases but not in central or basal nuclei. These patterns of cell loss in the amygdala do not differ from previous studies in both humans and animal models of chronic epilepsy suggesting that there is not a specific pattern of amygdaloid sclerosis in SUDEP patients which could implicate a functional role for this nucleus in the mechanism of the sudden death.