Cardiorespiratory and autonomic function in epilepsy: implications for clinical practice
Document TypePhD thesis
Access StatusThis item is embargoed and will be available on 2021-09-16.
© 2019 Shobitha Sivathamboo
Epilepsy is one of the most common serious neurological disorders in the world, affecting over 70 million people worldwide. It is associated with an increased risk of premature mortality as a direct or indirect consequence of seizures, epilepsy, comorbidities, and treatments for epilepsy. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in epilepsy, where proposed mechanisms are thought to be seizure-induced brainstem, arousal, and cardiorespiratory dysfunction. Dysfunction to cardiorespiratory and autonomic function has long been recognized, and growing evidence points to its implication in SUDEP. However, comprehensive studies using multimodal physiological monitoring are limited, and a better understanding may improve outcomes in patients with epilepsy. The overall aim of this thesis was to investigate cardiorespiratory and autonomic function in patients with epilepsy to determine the relevance that this may have for outcomes in patients with epilepsy. Firstly, I examined the prevalence and risk factors for sleep-disordered breathing in patients routinely screened using diagnostic polysomnography who were admitted for video-encephalogram (EEG) monitoring, using current guidelines and recommended polysomnography techniques. This study identified a high prevalence of clinically significant sleep-disordered breathing in this population and risk-factors to help guide selection of patients for referral to laboratory-based polysomnography where concurrent video-EEG monitoring and polysomnography is unavailable. Secondly, I examined mortality in patients who had a diagnosis of epilepsy and/or PNES who were found to have sleep-disordered breathing in the first study. Though a higher proportion of deceased patients with clinically significant sleep-disordered breathing compared to living patients was found, we did not find an association between sleep-disordered breathing and mortality. Larger studies with a greater follow-up duration are warranted. Thirdly, I examined cardiorespiratory and autonomic function in patients with epilepsy before, during, and after convulsive and non-convulsive seizures. This study demonstrates substantial cardiorespiratory and autonomic dysfunction among convulsive seizures which may explain why these seizures carry the greatest risk of SUDEP. Lastly, I examined the incidence and frequency of cardiac arrhythmias in a population with drug-resistant chronic epilepsy using implantable cardiac monitors. This study identified that patients with chronic drug resistant epilepsy have a high incidence of cardiac arrhythmias. Two patients had potentially fatal cardiac arrhythmias requiring further cardiology management including sinus arrest and ventricular asystole requiring permeant pacemaker insertion, and polymorphic wide complex tachycardia associated with febrile tonic-clonic seizures. Overall, the findings of this thesis demonstrate cardiorespiratory and autonomic dysfunction are common in drug-resistant epilepsy and warrants the more widespread application of multimodality physiological monitoring including incorporating continuous respiratory monitoring and polysomnography in epilepsy monitoring units, which is not currently standard practice.
Keywordsepilepsy; SUDEP; cardiorespiratory; cardiac arrhythmias; sleep; sleep-disordered breathing; heart-rate variability; cardiovascular; mortality
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