[Temporal lobe epilepsy: effect of focus side on the autonomic regulation of heart rate?]

Frequency of peri-ictal apnea and cardiac arrhythmias in epileptic seizures

Background

Available data from witnessed and monitored sudden unexpected death in epilepsy (SUDEP) cases postulate that ictal central apnea (ICA) and ictal arrhythmias are the main causes of SUDEP. ICA is a frequent semiological feature of focal epilepsy and occasionally the only clinical manifestation of focal seizures. The aim of this study was to assess the frequency of ICA and cardiac arrhythmias in epileptic patients and to study the risk factors and predictors of their occurrence.

Methods

Fifty patients diagnosed with epilepsy were recruited in this study. All participants underwent prolonged surface video electroencephalography (VEEG) study using the 10-20 international electrode system with concomitant polysomnography including electrocardiography (ECG), heart rate monitoring, and peripheral capillary oxygen saturation (SpO2) using pulse oximetry. Also inductance plethysmography was used to record chest and abdominal excursions.

Results

Complete datasets were available in 50 patients and 112 seizures were recorded. ICA occurred exclusively in focal epilepsy (P <0.001). Temporal lobe epilepsy was associated with higher occurrence of ICA in comparison to extratemporal epilepsy (P <0.001). In addition, seizures lateralized to the left hemisphere were associated with higher occurrence of ICA (P <0.001). On the other side, tachycardia was found to be more associated with temporal lobe epilepsy and left hemispheric seizure onset (P <0.001).

Conclusion

ICA occurred exclusively in focal seizures and tachycardia magnitude was more with focal seizures, and both had higher percentage in temporal lobe epilepsy in comparison to other types and in seizures with left hemispheric onset.

Pre-ictal heart rate changes: A systematic review and meta-analysis

PURPOSE

To estimate the incidence of pre-ictal heart rate (HR) manifestations and to identify clinical and study-related factors modulating the estimate.

METHODS

We searched articles recording concurrent pre-ictal EEG and HR in adults and children with epilepsy. Pre-ictal HR changes were classified as HR reduction (HRR) or increase (HRI). Studies reporting the total number of seizures and the number of seizures with pre-ictal HR changes were included in a random-effects meta-analysis. A random-effects meta-regression was used to identify variables affecting study heterogeneity.

RESULTS

Thirty studies, including 1110 participants and 2957 seizures, were included. The meta-analysis showed a pooled incidence of pre-ictal HRI of 36/100 seizures (95% CI 22-50). The pre-ictal HRI incidence was 44/100 seizures (95% CI 33-55) in studies including temporal lobe epilepsy, 55/100 seizures (95% CI 41-68) in studies enrolling adults and 35/100 seizures (95% CI 16-58) when patients on antiepileptic drugs were included. The meta-regression showed that the age group, the length of the pre-ictal period, the incidence of ictal tachycardia and the time of onset of the pre-ictal HRI had a significant impact on estimates variability. The pooled incidence of pre-ictal HRR was 0/100 seizures (95% CI 0-1).

CONCLUSION

Review of bias evaluation and methods assessment disclosed several major limitations in the evidence-base. HR monitoring could be valuable to identify seizures prior to their apparent onset, opening the possibility to early interventions. Additional effort is necessary to delineate the target population who might benefit from its use and the mechanisms sustaining the pre-ictal cardiac changes.

Exercise-induced seizures and lateral asymmetry in patients with temporal lobe epilepsy

Objective

The objective of this case report is to better characterize the clinical features and potential pathophysiological mechanisms of exercise-induced seizures.

Methods

We report a case series of ten patients from a tertiary epilepsy center, where a clear history was obtained of physical exercise as a reproducible trigger for seizures.

Results

The precipitating type of exercise was quite specific for each patient, and various forms of exercise are described including running, swimming, playing netball, dancing, cycling, weight lifting, and martial arts. The level of physical exertion also correlated with the likelihood of seizure occurrence. All ten patients had temporal lobe abnormalities, with nine of the ten patients having isolated temporal lobe epilepsies, as supported by seizure semiology, EEG recordings, and both structural and functional imaging. Nine of the ten patients had seizures that were lateralized to the left (dominant) hemisphere. Five patients underwent surgical resection, with no successful long-term postoperative outcomes.

Conclusions

Exercise may be an underrecognized form of reflex epilepsy, which tended to be refractory to both medical and surgical interventions in our patients. Almost all patients in our cohort had seizures localizing to the left temporal lobe. We discuss potential mechanisms by which exercise may precipitate seizures, and its relevance regarding our understanding of temporal lobe epilepsy and lateralization of seizures. Recognition of, as well as advice regarding avoidance of, known triggers forms an important part of management of these patients.

Peri-ictal ECG changes in childhood epilepsy: implications for detection systems

Early detection of seizures could reduce associated morbidity and mortality and improve the quality of life of patients with epilepsy. In this study, the aim was to investigate whether ictal tachycardia is present in focal and generalized epileptic seizures in children. We sought to predict in which type of seizures tachycardia can be identified before actual seizure onset. Electrocardiogram segments in 80 seizures were analyzed in time and frequency domains before and after the onset of epileptic seizures on EEG. These ECG parameters were analyzed to find the most informative ones that can be used for seizure detection. The algorithm of Leutmezer et al. was used to find the temporal relationship between the change in heart rate and seizure onset. In the time domain, the mean RR shows a significant difference before compared to after onset of the seizure in focal seizures. This can be observed in temporal lobe seizures as well as frontal lobe seizures. Calculation of mean RR interval has a high specificity for detection of ictal heart rate changes. Preictal heart rate changes are observed in 70% of the partial seizures. Ictal heart rate changes are present only in partial seizures in this childhood epilepsy study. The changes can be observed in temporal lobe seizures as well as in frontal lobe seizures. Heart rate changes precede seizure onset in 70% of the focal seizures, making seizure detection and closed-loop systems a possible therapeutic alternative in the population of children with refractory epilepsy.