Ictal tachycardia: The head–heart connection

Epileptic seizures can lead to changes in autonomic function affecting the sympathetic, parasympathetic, and enteric nervous systems. Changes in cardiac signals are potential biomarkers that may provide an extra-cerebral indicator of ictal onset in some patients. Heart rate can be measured easily when compared to other biomarkers that are commonly associated with seizures (e.g., long-term EEG), and therefore it has become an interesting parameter to explore for detecting seizures. Understanding the prevalence and magnitude of heart rate changes associated with seizures, as well as the timing of such changes relative to seizure onset, is fundamental to the development and use of cardiac based algorithms for seizure detection. We reviewed 34 articles that reported the prevalence of ictal tachycardia in patients with epilepsy. Scientific literature supports the occurrence of significant increases in heart rate associated with ictal events in a large proportion of patients with epilepsy (82%) using concurrent electroencephalogram (EEG) and electrocardiogram (ECG). The average percentage of seizures associated with significant heart rate changes was similar for generalized (64%) and partial onset seizures (71%). Intra-individual variability was noted in several articles, with the majority of studies reporting significant increase in heart rate during seizures originating from the temporal lobe. Accurate detection of seizures is likely to require an adjustable threshold given the variability in the magnitude of heart rate changes associated with seizures within and across patients.     

The association of cardiac asystole with partial seizures: does it result from ictal or interictal activity?

Bradycardia or asystole that occur during some seizures may be life threatening as a leading cause of SUDEP. A patient with right and left temporal lobe onset seizures and preceding bardycardia or asystole is presented. He had bilateral hippocampal atrophy on MRI. The unreliability of ictal bradycardia or asystole as a lateralizing sign in patients with partial epilepsy and the role of interictal autonomic activity in heart rate changes during seizures are discussed.     

Interictal change in cardiac autonomic function associated with EEG abnormalities and clinical symptoms: a longitudinal study following acute deterioration in two patients with temporal lobe epilepsy

The purpose of the present study was to investigate the ictal and interictal changes in cardiac autonomic function (CAF), and the relationship between the interictal change in CAF to the electroencephalogram (EEG) and clinical findings. In two patients with temporal lobe epilepsy (TLE) showing acute deterioration, a quantitative evaluation of their interictal CAF based on heart rate variability and their EEG using spectral analysis was conducted, and the findings compared with repeated clinical evaluations during the recovery period. The ictal heart rate changes and their temporal relationship to ictal discharge were investigated using simultaneous EEG/electrocardiogram (ECG) monitoring in one of the patients. Interictal parasympathetic function was decreased during the period of acute deterioration, but was increased in association with improvements in the EEG and clinical findings. In contrast, the sympathetic function showed no specific changes. The ictal discharges were preceded by a brief bradycardia, with a long delay of up to 40s. The results demonstrated that this decrease in parasympathetic function was closely related to the interictal changes in central nervous system function. On the other hand, the ictal discharges in one of the patients were thought to have caused a transient elevation of parasympathetic function. It is strongly suggested that patients with TLE have interictal as well as ictal changes in CAF that are mediated mainly through the parasympathetic nervous system.     

Electrocardiographic changes at the onset of epileptic seizures

PURPOSE: We studied heart-rate (HR) changes at the transition from the preictal to the ictal state in patients with focal epilepsies to gain some insight into the mechanisms involved in the neuronal regulation of cardiovascular function. METHODS: We assessed ECG changes during 145 seizures recorded with scalp EEG in 58 patients who underwent video-EEG monitoring. Consecutive RR intervals were analyzed with a newly developed mathematical method for a total of 90 s. RESULTS: Ictal-onset tachycardia occurred in 86.9% of all seizures, whereas bradycardia was documented only in 1.4%. The incidence as well as the amount of ictal HR increase was significantly more pronounced in patients with mesial temporal lobe epilepsy (TLE) as compared with those with non-lesional TLE or extratemporal epilepsy. Moreover, right hemispheric seizures were associated with ictal-onset tachycardia. On average, ictal HR increase preceded EEG seizure onset by 13.7 s in TLE patients and 8.2 s in patients with extratemporal epilepsy. This difference was significant. Ictal HR changes could be classified according to their temporal evolution into two different patterns. These two patterns differed significantly between the temporal lobe and the extratemporal epilepsy patient group. CONCLUSIONS: Epileptic discharges directly influence areas of the central autonomic network, thus regulating HR and rhythm. Such changes occur before ictal discharges appear on surface electrodes. Our newly developed method may be of potential use for clinical applications such as automatic seizure-detection systems. Moreover, our method might help to clarify further the basic mechanisms of interactions between heart and brain.     

Can heart rate variability in children with epilepsy be used to predict seizures?

PurposeThe aim of this study was to examine interictal, pre-ictal and ictal autonomic system disturbance by comparing heart rate variability in children with uncontrolled epilepsy with that seen in healthy controls and children with controlled epilepsy.MethodsOur study group included 20 children with refractory epilepsy, our control groups were composed of 20 children with well-controlled epilepsy and 20 healthy children. All subjects were evaluated by Holter ECG monitoring and 12-lead ECG to assess heart rate variability and QTc dispersion. The study group was also evaluated by Holter ECG during seizures.ResultsThe study group exhibited significantly more pathological QTc dispersion than did the control groups. Heart rate variability was significantly suppressed: reduced parasympathetic activity with lower low frequency (LF) and high frequency (HF) band values were observed in the study group. Findings were similar in the well-controlled epilepsy group and the healthy group but differed from the uncontrolled epilepsy group. The examination of heart rate variability parameters during and before seizures revealed higher nLF and LF/HF ratio and lower nHF values demonstrating increased sympathetic activity.ConclusionWe suggest that children with refractory epilepsy have abnormalities of autonomic nervous system functioning which could be linked to the increased risk of sudden unexpected death seen in the patient group. It is possible that a chronically reduced vagal tone predisposes patients to a more dramatic stress response during their seizures. It is possible that heart rate variability parameter arising prior to seizures could be used to predict future seizures.     

Cardiovascular manifestations of autonomic epilepsy

Cardiovascular autonomic manifestations of seizures occur frequently in the epileptic population. Common manifestations include alterations in heart rate and rhythm, blood pressure, ECG changes and chest pain. The neuroanatomical and neurophysiological underpinnings of these autonomic manifestations are not been fully elucidated. Diagnostic confusion may arise when ictal symptoms are confined to the autonomic nervous system; conversely, such symptoms in association with convulsions or altered consciousness are more readily recognized as concomitant ictal features. Awareness of the diverse autonomic manifestations of epilepsy will enhance diagnosis and lead to more effective therapy of these patients.     

Electrocardiographic changes during electrographic seizures

The occurrence of high-risk cardiac arrhythmias during electrographic seizures has been proposed as a possible cause for sudden unexpected death in patients with epilepsy. Several anecdotal case reports have documented various cardiac irregularities during seizures. We reviewed simultaneous 24-hour electroencephalographic - electrocardiographic studies obtained by ambulatory cassette electroencephalography in 45 patients who experienced 106 electrographic seizures. An increase in heart rate was seen in 96% of seizures, while in four seizures, the rate was unchanged. Heart rate increase measured from 1 minute preictally to intraictal peak ranged from 0% to 160% (mean, 60%). The onset of tachycardia was usually within several seconds (before or after) of the seizure onset, and often persisted for several minutes after termination of the discharge. No difference was found in patients with lateralized vs generalized seizures. Neither ventricular ectopia, conduction defects, or bradycardia were observed during the ictal episodes. We conclude that ictal tachycardia is the rule during electrographic seizures, and that high-risk cardiac arrhythmias are uncommon.     

Comparison of heart rate variability parameters during complex partial seizures and psychogenic nonepileptic seizures

Purpose: Psychogenic nonepileptic seizures (PNES) superficially resemble epileptic seizures. Little is known about ictal autonomic nervous system (ANS) activity changes in epilepsy and PNES. This study compares ictal heart rate variability (HRV) parameters as a reflection of ANS tone in epileptic seizures and PNES, and explores differences between interictal and ictal ANS tone in both patient groups. Methods: Ictal HRV parameters were extracted from single‐lead electrocardiography (ECG) data collected during video–electroencephalography (EEG) recordings of 26 patients with medically refractory temporal lobe epilepsy and 24 age‐ and sex‐matched patients with PNES. One seizure per patient in a resting, wake, supine state was analyzed. Interictal ECG data were available for comparison from 14 patients in both groups. HRV parameters in time and frequency domains were analyzed (low frequency [LF], high frequency [HF], standard deviation of all consecutive normal R wave intervals [SDNN], square root of the mean of the sum of the squares of differences between adjacent normal R wave intervals [RMSSD]). CVI (cardiovagal index), CSI (cardiosympathetic index), and ApEn (approximate entropy) were calculated from Lorenz plots. Key Findings: There were significant differences between ictal HRV measures during epileptic and nonepileptic seizures in the time and frequency domains. CSI (p < 0.001) was higher in epileptic seizures. Time interval between two consecutive R waves in the ECG (RR interval) (p = 0.002), LF (p = 0.02), HF (p = 0.003), and RMSSD (p = 0.003) were significantly lower during epileptic seizures. Binary logistic regression yielded a significant model based on the differences in CSI classifying 88% of patients with epilepsy and 73% of patients with PNES correctly. The comparison between resting and ictal states in both seizure disorders revealed significant differences in RR interval (epilepsy p < 0.001, PNES p = 0.01), CSI (epilepsy p < 0.001, PNES p = 0.02), HF (epilepsy p = 0.002, PNES p = 0.03), and RMSSD (epilepsy p = 0.004, PNES p = 0.04). In patients with epilepsy there were also significant differences in ictal versus interictal mean values of ApEn (p = 0.03) and LF (p = 0.04). Although CSI was significantly higher, the other parameters were lower during the seizures. Stepwise binary regression in the 14 patients with epilepsy produced a significant model differentiating resting state from seizures in 100% of cases. The same statistical approach did not yield a significant model in the PNES group. Significance: Our results show greater ANS activation in epileptic seizures than in PNES. The biggest ictal HRV changes associated with epileptic seizures (CSI, HF, and RMSSD) reflect high sympathetic system activation and reduced vagal tone. The reduced ApEn also reflects a high sympathetic tone. The observed ictal alterations of HRV patterns may be a more specific marker of epileptic seizures than heart rate changes alone. These altered HRV patterns could be used to detect seizures and also to differentiate epileptic seizures from PNES. Larger studies are justified with intergroup and intragroup comparisons between ictal and resting states.     

Effects of seizure repetition on postictal and interictal neurocardiac regulation in the rat

PURPOSE: Human epilepsy is associated with abnormalities in cardiac regulation, as measured by reductions of heart rate variability (HRV) and approximate entropy (ApEn), but it is not known how these abnormalities are related to seizure experience. METHODS: Baseline electrocardiogram (ECG) was recorded from seizure-naive rats. They were subjected daily to maximal electroshock (MES), which induced tonic seizures with hindlimb extension, for a total of 10 days. ECG was obtained for 30 min before and after the first and last seizure. R-R variability, spectral variability, and ApEn were calculated to determine changes in pre- and postictal cardiac regulation. Before the last seizure, interictal parameters were compared with baseline values to determine changes in interictal HRV as a consequence of seizure repetition. Postictal values obtained after the last seizure were compared with the initial postictal data to look for changes in postictal cardiac regulation. RESULTS: During the postictal state, a mild, but significant, loss of ApEn was present after either the first or last seizure. Seizure repetition induced loss of R-R variability and high-frequency spectral band, which was present both interictally and postictally. CONCLUSIONS: The results suggest that convulsive seizures are associated with an immediate reduction of the complexity of cardiac rhythm regulation, as reflected by reductions of ApEn. Seizure repetition may induce long-term neural abnormalities in neurocardiac regulatory systems, especially parasympathetic, which limit appropriate autonomic responses. These acquired abnormalities may, in turn, predispose individuals to cardiac arrhythmia and sudden unexpected death in epilepsy.     

Bradycardia and asystole during generalised interictal EEG discharges

Few studies have investigated the effects of interictal epileptic discharges on the cardiac autonomic system. This study reports the case of a 37‐year‐old man with refractory generalised epilepsy, who recently reported an increase in frequency of nocturnal tonic‐clonic seizures, not responding to treatment. During the nocturnal video study, in non‐rapid eye movements sleep, we recorded 106 generalised sharp‐ and polyspike‐waves lasting for 3 to 7 seconds, associated with bradycardia and asystole, without behavioural changes and without increase in deltoid muscle activity. The asystole had a duration of between 3 and 8 seconds. In one case, a 7 second asystole was associated with a tonic‐clonic generalised seizure. A 24‐hour electrocardiographic study revealed a bradycardia and a Wenckebach atrioventricular block. Heart rate analysis at the time of the interictal epileptic discharges revealed an abrupt increase in the RR interval, occurring simultaneously with the onset of interictal epileptic discharges and followed by a return to values below baseline value. A cardiac pacemaker was installed with a reduction of asystole length during the interictal epileptic discharges. Our findings indicate, for the first time, the role of interictal generalised discharges in EEG‐related asystole and bradycardia. These data support the hypothesis that some patients with epilepsy may be predisposed to disturbances of the autonomic cardiac system.     

Electrocardiographic and oximetric changes during partial complex and generalized seizures

Significant autonomic changes occur during seizures and may be related to sudden unexplained death in epilepsy (SUDEP). Accordingly, we performed a study to determine the prevalence of heart rate, QTc, and oximetric changes during seizures and analyzed their association with SUDEP risk factors. We analyzed 218 seizures from 76 patients. Ictal sinus tachycardia occurred in 57% of seizures and was associated with ≥3 failed AEDs (p=0.001), generalized seizures (p<0.001), and normal brain MRI (p=0.04). Ictal sinus bradycardia was rare, occurring in 2% of seizures. Ictal bradycardia was associated with seizure clustering (p=0.028) and reported history of ≥50 seizures/month (p=0.01). Depending on the correction formula utilized for calculating QTc, clinically significant ictal QTc prolongation (≥460ms for children ≤13 years, ≥470ms for males age >13, and ≥480ms for females age >13) occurred in 4.8-16.2% of seizures, while ictal QTc prolongation ≥500ms occurred in 2.9-16.2%. Ictal QTc shortening ≤340ms was observed in 3.8-4.8% of seizures. Ictal hypoxemia occurred in 25% of seizures and was associated with normal MRI (p=0.01), longer seizure duration (p=0.049), and ictal tachycardia (p=0.003). Such findings may have implications for understanding the pathogenesis of SUDEP.     

Heart rate increase in otherwise subclinical seizures is different in temporal versus extratemporal seizure onset: support for temporal lobe autonomic influence.

Ictal heart rate was investigated in otherwise subclinical epileptic seizures to test the hypothesis as to whether ictal tachycardia is physiological and not a physical or psychological stress response. In addition, we aimed to evaluate the localizing significance of pure ictal tachycardia. We included 21 epilepsy patients, who showed an ictal EEG seizure pattern during 22, otherwise subclinical seizures. All patients underwent ictal video-EEG recordings to evaluate the possibility of resective epilepsy surgery. The changes in heart rate in these patients were investigated in order to determine their relationship to localization and duration of EEG seizure patterns. Ictal tachycardia was observed in 41% of the otherwise subclinical seizures (nine out of 22), and significantly more often in seizures arising from the temporal lobe than from extratemporal regions (62% versus 11%, p < 0.0018). The seizure duration as defined by EEG was significantly positively correlated with an increase of heart rate (p = 0.043). Ictal heart rate can increase as a result of epileptic activation of autonomic cortex, reflecting a temporal lobe autonomic influence. Thus, measurement of heart rate should be included in the evaluation of otherwise subclinical epileptic seizures, because of its localizing value.     

Time-frequency mapping of R-R interval during complex partial seizures of temporal lobe origin

BACKGROUND: Activation of autonomic nervous system is common with seizures. No reliable biological markers of impending seizures have been found. Evaluation of autonomic changes might help elucidate the transition from interictal to ictal states. METHODS: We studied twelve patients (eight females, four males), from 19 to 62 years old with temporal lobe complex partial seizures (CPS). Dynamics of autonomic functions from oscillations in R-R interval (RRI) using time-frequency mapping based upon a Wigner distribution during pre-ictal, ictal and post-ictal periods. Oscillations in RRI at respiratory frequencies (RF) (> 0.1 Hz) are parasympathetically mediated and at nonrespiratory frequencies (NONRF) (0.01-0.09 Hz) are under combined sympathetic and parasympathetic influence. RESULTS: CPS evoked marked autonomic imbalance and tachycardia. Spectral powers at both RF_RRI and NONRF_RRI increased over the pre-ictal period. RF_RRI power then fell rapidly over the 30 s before seizure onset and remained markedly reduced during seizure (P < 0.004). NONRF_RRI power reached a maximum at seizure onset and declined to a minimum before the seizure cessation (P < 0.05). CONCLUSION: Time-frequency analysis revealed that autonomic activation hallmarks clinical seizure onset for several minutes. After combined parasympathetic and sympathetic activation, rapid parasympathetic withdrawal occurred approximately 30 s before the seizure, and sympathetic activation peaks at seizure onset. Therefore, the transition from interictal to ictal states is relatively long and associated with subclinical autonomic changes.     

Profiles of instant heart rate during partial seizures

Instant heart rate (R-R intervals) can be readily studied during spontaneous seizures recorded with ambulatory cassette AEEG/AECG techniques. Ninety-three seizures were recorded in 32 patients with complex partial epilepsy. Instant R-R interval plots showed that 74% of seizures were associated with a dominant tachycardia, the most characteristic features of which were the initial steep acceleration phase at seizure onset and the wide fluctuations in heart rate ('exaggerated sinus arrhythmia') which occurred during and immediately after the seizure. Five percent of seizures were associated with a dominant but transient phase of heart rate slowing during or towards the end of the seizure. Nineteen percent of seizures showed equivocal or negative ictal effects on the heart rate and rhythm despite unequivocal AEEG seizure discharges. Conversely, other patients had characteristic heart rate changes despite equivocal AEEG abnormality. The heart rate profiles showed striking seizure-to-seizure similarities when multiple fits were recorded in the same patient. Ratemeter profiles may be clinically useful to locate epileptic seizures in long duration records; they can help to locate seizures which are either inaccurately timed or poorly identified by the event marker, or not clearly associated with definite AEEG changes. The secondary cardiac effects of epilepsy may be misdiagnosed if their primary cerebral origin is not suspected.     

Ictal video-polysomnography and EEG spectral analysis in a child with severe Panayiotopoulos syndrome.

OBJECTIVE: To describe the ictal polysomnographic features of a patient with Panayiotopoulos syndrome, a peculiar epileptic syndrome characterized by infrequent, often single, prolonged, nocturnal, focal seizures comprising an unusual constellation of autonomic symptoms (malaise, nausea, pallor, tachycardia, vomiting) and unilateral deviation of the eyes at the onset of seizures. These clinical, ictal manifestations are rarely followed by post-ictal headache. In the literature, there is little information on the ictal EEG characteristics of Panayiotopoulos syndrome and, in particular, on certain autonomic manifestations, such as tachycardia, as the sole ictal phenomena at the onset of seizures. METHODS AND RESULTS: One, all-night videopolysomnography, during which one seizure was recorded. Video-EEG data were evaluated visually and by means of quantitative spectral analysis. The spectral analysis of the recorded seizure showed a complex ictal pattern of cortical involvement with focal onset in the right occipital area followed by the recruitment of widespread extra-occipital cortical regions. CONCLUSIONS: This is the first such analysis of this peculiar epileptic condition. Most of the symptoms were consistent with a diagnosis of severe Panayiotopoulos syndrome, although the patient also presented "atypical findings": a relatively high frequency of seizures, post-ictal headache, no spontaneous remission of seizures with age, and late onset of visual hallucinations; this last finding is more frequent in "Gastaut-type childhood occipital epilepsy", in which onset typically occurs later than in Panayiotopoulos syndrome. [Published with video sequences].     

Heart rate changes and ECG abnormalities during epileptic seizures: prevalence and definition of an objective clinical sign

PURPOSE: To determine the prevalence of heart rate changes and ECG abnormalities during epileptic seizures and to determine the timing of heart rate changes compared to the first electrographic and clinical signs. To assess the risk factors for the occurrence of ECG abnormalities. METHODS: We analyzed retrospectively 281 seizures in 81 patients with intractable epilepsy who had prolonged video-EEG and two-channel ECG. The nature and timing of heart rate changes compared to the electrographic and clinical seizure onset was determined. The ictal period (including one minute preictally and three minutes postictally) was analyzed for cardiac arrhythmias, conduction and repolarization abnormalities. Risk factors for cardiac abnormalities were investigated using parametric and non-parametric statistics. RESULTS: There was an increase in heart rate of at least 10 beats/minute in 73% of seizures (93% of patients) and this occurred most often around seizure onset. In 23% of seizures (49% of patients) the rate increase preceded both the electrographic and the clinical onset. ECG abnormalities were found in 26% of seizures (44% of patients). One patient had an asystole for 30 seconds. Long seizure duration increased the occurrence of ECG abnormalities. No other risk factor was found. CONCLUSIONS: Heart rate changes occur frequently and occur around the time or even before the earliest electrographic or clinical change. The change can clarify the timing of seizure onset and the specific rate pattern may be useful for seizure diagnosis and for automatic seizure detection. ECG abnormalities occur often and repeatedly in several seizures of the same patient.     

Repeated amygdala-kindled seizures induce ictal rebound tachycardia in rats

It is thought that cardiovascular changes may contribute to sudden death in patients with epilepsy. To examine cardiovascular alterations that occur during epileptogenesis, we measured the heart rate of rats submitted to the electrical amygdala kindling model. Heart rate was recorded before, during, and after the induced seizures. Resting heart rate was increased in stages 1, 3, and 5 as compared with the unstimulated control condition. In the initial one third of the seizures, we observed bradycardia, which increased in intensity with increasing stage and was blocked by injecting methyl atropine. During stage 5 seizures, a rebound tachycardia was observed that also increased in intensity with increasing number of seizures. This study demonstrated the influence of seizure frequency on cardiac autonomic modulation, providing a basis for discussion of potential mechanisms that cause patients with epilepsy to die suddenly.     

Clinical cues for detecting ictal asystole

Objective The occurrence of asystole during an epileptic seizure is the most dramatic manifestation of ictal bradycardia. Recognition of ictal asystole is important as treatment with both antiepileptic drugs and cardiac pacing may be necessary. The purpose of this study was to identify clinical cues to aid in the detection of ictal asystole. Methods We analyzed the clinical and electrophysiologic features of all recorded seizures in consecutive patients diagnosed with ictal bradycardia and asystole on prolonged video-EEG/ECG monitoring over a 14 year period. Results Twenty-nine seizures with ictal bradycardia were identified in 13 patients. Of these, 11 seizures in seven patients were associated with asystole. Bilateral transient limb movements consisting of asymmetric posturing or jerking occurred during eight episodes of ictal asystole, and loss of muscle tone occurred during four. In contrast, neither bilateral limb movement nor loss of muscle tone was observed in any of the non-asystolic seizures, whether ictal bradycardia was present or not. All patients with ictal asystole reported a history of seizure-related falls and brief body and limb jerking. Conclusions The presence of loss of muscle tone or bilateral asymmetric jerky limb movements during a seizure suggests the possibility of ictal asystole. Video-EEG/ECG monitoring should be considered in patients with epilepsy demonstrating these clinical features to determine if ictal asystole is present.     

Left vagus nerve stimulation with the neurocybernetic prosthesis has complex effects on heart rate and on its variability in humans

PURPOSE: The purpose of this study was to determine if stimulation of the left vagus nerve (LVNS) with the neurocybernetic prosthesis (NCP) in humans is, as claimed in the literature, without cardiac chronotropic actions. METHODS: We analyzed 228 h of ECG recorded from five subjects with intractable epilepsy who had not benefited from LVNS, for effects on instantaneous heart rate (IHR) and heart rate variability (HRV). RESULTS: There were two main cardiac responses: (a) bradycardia, and (b) tachycardia during the first half, followed by bradycardia during the second half of stimulation (biphasic response). Multiphasic responses characterized by alternating bradycardia and tachycardia were rarely observed. HRV was either increased or decreased depending on the subject and on the stimulation parameters. HRV as a function of HR also showed high interindividual variability, and interestingly, in one case behaved paradoxically, increasing at higher and decreasing at lower heart rates. CONCLUSIONS: LVNS at high intensities has complex effects on IHR and HRV, which show large interindividual variability. These spectra of cardiac responses reflect the interplay of autonomic, visceral, and somatic sensory afferences and the role of central structures in their integration. These findings also point to the need for more comprehensive studies of cardiac function in humans implanted with the NCP, using sensitive methods for data processing and analysis such as those developed for this study.     

Physiologic autonomic arousal heralds motor manifestations of seizures in nocturnal frontal lobe epilepsy: implications for pathophysiology

ObjectiveThis study describes changes in heart rate (HR) and HR variability (HRV) related to clinical onset of seizures in nocturnal frontal lobe epilepsy (NFLE) in order to determine whether signs of autonomic activation precede onset of seizure motor manifestations, which was selected as seizure onset (SO). Further, to clarify the nature (epileptic or physiologic) of the changes in autonomic cardiac control presumed to precede SO, time-dependent variations in HR and HRV related to physiological cortical arousals associated with motor activity (phases of transitory activation, PAT) were also investigated.MethodsHR and HRV spectral power, quantified by means of wavelet transform, were analyzed in relation to the onset of motor manifestations in 45 NFLE seizures and 45 PAT derived from whole night video-polysomnographic recordings of ten patients and of ten control subjects, respectively.ResultsAnalysis of HRV showed a shift of sympathetic/parasympathetic cardiac control toward a sympathetic predominance in the 10 s immediately preceding SO, while changes in HR were evident only one second before SO. This sympathetic activation was not associated with a sleep-wake transition or changes in respiratory activity, both of which occurred concurrently with SO. Similar changes in HR and HRV were observed in the 10 s before the motor and electroencephalographic onset of PAT.ConclusionsOur study demonstrates that a similar autonomic activation precedes the motor manifestations of NFLE seizures and physiological arousal. This autonomic activation could represent part of the arousal response, which could be implicated in the occurrence of both seizure and arousal motor manifestations.