Athi Ponnusamy

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.

The role of stress as a trigger for epileptic seizures: a narrative review of evidence from human and animal studies.

Stress is one of the most frequently self‐identified seizure triggers in patients with epilepsy; however, most previous publications on stress and epilepsy have focused on the role of stress in the initial development of epilepsy. This narrative review explores the causal role of stress in triggering seizures in patients with existing epilepsy. Findings from human studies of psychological stress, as well as of physiologic stress responses in humans and animals, and evidence from nonpharmacologic interventions for epilepsy are considered. The evidence from human studies for stress as a trigger of epileptic seizures is inconclusive. Although retrospective self‐report studies show that stress is the most common patient‐perceived seizure precipitant, prospective studies have yielded mixed results and studies of life events suggest that stressful experiences only trigger seizures in certain individuals. There is limited evidence suggesting that autonomic arousal can precede seizures. Interventions designed to improve coping with stress reduce seizures in some individuals. Studies of physiologic stress using animal epilepsy models provide more convincing evidence. Exposure to exogenous and endogenous stress mediators has been found to increase epileptic activity in the brain and trigger overt seizures, especially after repeated exposure. In conclusion, stress is likely to exacerbate the susceptibility to epileptic seizures in a subgroup of individuals with epilepsy and may play a role in triggering “spontaneous” seizures. However, there is currently no strong evidence for a close link between stress and seizures in the majority of people with epilepsy, although animal research suggests that such links are likely. Further research is needed into the relationship between stress and seizures and into interventions designed to reduce perceived stress and improve quality of life with epilepsy.

Heart rate variability measures as biomarkers in patients with psychogenic nonepileptic seizures: Potential and limitations

Heart rate variability (HRV) metrics provide reliable information about the functioning of the autonomic nervous system (ANS) and have been discussed as biomarkers in anxiety and personality disorders. We wanted to explore the potential of various HRV metrics (VLF, LF, HF, SDNN, RMSSD, cardiovagal index, cardiosympathetic index, approximate entropy) as biomarkers in patients with psychogenic nonepileptic seizures (PNES). HRV parameters were extracted from 3-minute resting single-lead ECGs of 129 subjects (52 with PNES, 42 with refractory epilepsy and 35 age-matched healthy controls). Compared with healthy controls, both patient groups had reduced HRV (all measures P<0.03). Binary logistic regression analyses yielded significant models differentiating between healthy controls and patients with PNES or patients with epilepsy (correctly classifying 86.2 and 93.5% of cases, respectively), but not between patients with PNES and those with epilepsy. Interictal resting parasympathetic activity and sympathetic activity differ between healthy controls and patients with PNES or those with epilepsy. However, resting HRV measures do not differentiate between patients with PNES and those with epilepsy.

The safety of UK video telemetry units: Results of a national service evaluation §

PURPOSE To assess patient safety during seizures occurring on UK video telemetry units and identify factors in unit infrastructure which may improve safety with the intention of producing national guidelines. METHODS A prospective multicentre national service evaluation of the occurrence of adverse events and level of nurse attendance during seizures occurring on video telemetry units was performed. Data from 272 seizures from 27 video telemetry units across the UK were analysed. RESULTS Adverse events occurred in 12% of seizures: 7% were physical events such as falls or respiratory compromise and 5% were unnoticed seizures. Nursing staff did not attend the patients in 44% of seizures and attendance was delayed beyond 30s in a further 29%. Only 27% of seizures were attended by a Healthcare Professional within half a minute. The most important factor shown to improve timely attendance of patients during seizures was the presence of a nurse dedicated to the telemetry bed(s). The site of the telemetry bed (bay or cubicle) and method of observation (direct or indirect) was less important. An optimal nurse-to-patient ratio was difficult to identify but the study suggests that a ratio of at least 1 nurse to 4 patients is appropriate. CONCLUSION The results provide an evidence base for the production of national standards and guidelines for surveillance of patients during video telemetry to improve patient safety.

Ictal hiccup during absence seizure in a child

Absence seizures are one of the features of idiopathic generalised epilepsy (IGE) and occur as component of many different syndromes. They are commonly associated with various clinical features such as mild clonic components, change in postural tone, automatisms and autonomic phenomena. Childhood absence epilepsy (CAE) is the prototype IGE with typical absence seizures. We report a child who had prominent ictal hiccups during an absence seizure, and discuss the possible mechanisms. [Published with video sequences].

Recent Advances in Predicting and Preventing Epileptic Seizures

This book is an ideal way for clinicians and researchers in epileptology to update themselves about current concepts and knowledge of pathophysiological seizure generation mechanisms and ongoing developments in seizure prediction strategies. The book especially highlights the importance of multidisciplinary teamwork involving experts in the neurosciences, mathematics, physics, and engineering (especially complex signal processing), if progress toward seizure prediction and prevention is to be made. The initial chapter addresses the current concept of what an epileptic network is and explains the differences in the mechanisms underlying interictal spikes and pre-ictal spiking during critical state transition into seizures. A candid summary of the current state of knowledge about deep brain stimulation for intractable epilepsy and description of all potential stimulation sites and parameters is provided. The book goes on to produce an overview of the current principles of computer modeling of seizures and epilepsy. Both stochastic and deterministic approaches are explained. The first ever online estimation of neural mass model parameters in terms of excitatory and inhibitory synaptic strength estimation of a seizure recorded using ECoG in a patient with epilepsy is presented. The spatiotemporal modeling of microseizures from a mesoscale of cortical sheet is described, and the influence of different neuronal dynamics and network topology (lattice vs. small world vs. random type) on global synchrony is explained with great clarity. Great emphasis is given to the contributions that signal processing techniques can make toward the understanding of neural network functioning in epilepsy with particular relevance to pathophysiology and early seizure detection or prediction. Seminal works from in vitro network analyses based on animal models as well as in vivo analyses of human epileptic patients examined with intracranial EEG recordings are presented and discussed in detail. All sections highlight the findings of clinical

Complex partial seizures: Going out with a hiccup

1. IntroductionComplex partial seizures commonly manifest with diverse ictalbehaviours and phenomena, however hiccups are infrequentlydescribed.Tothebestofourknowledgeictalhiccupshavenotbeendocumented with video EEG correlation in complex partialseizures. Here, we describe two patients, both with structurallesions and concordant EEG findings, in whom hiccups occurtowards the end of seizures. We discuss the origin of the hiccupsand their contribution to the seizure course.2. Case oneA 73 year old lady with a 57 year history of complex partialseizuresandoccasionalsecondarygeneralisationwasadmittedforvideo telemetry as a part of her pre-surgical evaluation. Typicalcomplex partial seizures were characterised by right arm move-ments and, when standing, falls that sometimes resulted in injury.MRI imaging had demonstrated right mesial temporal sclerosis(Fig. 1a, i–iii). Her seizures had proved refractory to multiple anti-epileptic medications and on admission she was taking lamo-trigine125 mgtwicedaily,levetiracetam250 mgtwicedaily(bothof which were stopped during telemetry) and zonisamide 100 mgtwicedaily(whichwascontinued).Seizurefrequencyatthetimeofadmissionwasaround2permonth.HerrestingEEGdemonstratednormalposteriorbackgroundrhythmwithfrequentshortburstsofsharp waves/spikes in the right temporal region, maximalanteriorly. During the recording the patient had 3 seizures eachlasting around 2 min, clinical and EEG changes were similar in allevents. Attacks began with right hand automatism and slow headversion, followed by chewing movements (Video 1). This wasfollowed by clonic movements of the left hand and then, on eachoccasion,hiccups;shortlyafterhiccuponsettheseizuresended.Nohiccups were recorded outside of seizure events. During theseizures prominentrhythmical ictalepileptiform discharges in thethetafrequencywereapparentovertherighttemporalregionwithanterior emphasis. Bihemispheric involvement soon followed butthe right anterior temporal dominance remained intact. Followingthe attacks she was confused and wandered around the bed.Subsequently the patient underwent a right selective amygdalo-hippocampectomy and no seizures have been reported post-operatively during one year follow up.3. Case twoA 23 year old lady presented with frequent seizures sinceinfancy. Seizures were typically complex partial events charac-terised by fidgeting and occasional vocalisation and/or secondarygeneralisation. Occasional simple partial events characterised by‘‘tingling’’ sensations over the left side of the body were alsoreported,aswerenocturnalseizures.Seizurefrequencyatthetimeof recording was approximately 8 per month. She was beingtreated with levetiracetam 1500 mg (reduced to 500 mg duringrecording), topiramate 200 mg and carbamazepine 800 mg, alltwice daily. MRI imaging demonstrated a gliotic lesion in the rightparietal lobe (Fig. 2a), possibly a previous ischaemic insult. Rightmesial temporal sclerosis was also present (Fig. 2b). Resting EEGdemonstrated normal alpha rhythm bilaterally and irregular slowwave activity over the right fronto-temporal region. Additionally,intermittent sharp waves were noted over the right temporal

Home video telemetry in children: A comparison to inpatient video telemetry

PURPOSE Home Video Telemetry (HVT) combines ambulatory EEG with simultaneous video recording. No previous reports have compared HVT and inpatient video telemetry (IVT) in a purely paediatric population. This study compares HVT and IVT in this group in terms of diagnostic efficacy, recording quality and acceptability to parents/carers. METHODS 33 HVT and 29 IVT patients aged 1-17 years were included. Information regarding patient demographics, ictal capture, diagnostic utility, recording quality (e.g. video clarity, EEG artefacts) and parent/carer preferences was documented. Difficulties using HVT equipment were recorded. RESULTS 62% of IVT patients and 64% of HVT patients had typical attacks during the recording. 59% of IVT and 70% of HVT recordings were considered to have answered the referral question. Study quality was similar in both groups. In HVT studies the rate of equipment difficulties was 52%; problems included camera positioning and failure to turn on the infrared button at night. Diagnostic information was lost in 15% of patients. 76% of parents/carers of HVT patients would choose this investigation again. CONCLUSIONS The diagnostic efficacy and study quality of HVT and IVT are similar in paediatric patients. HVT is acceptable to most parents/carers. User error may compromise the investigation in a minority of cases but did not impact on diagnostic utility. Adoption of HVT investigation could provide an accessible and economic alternative to IVT.

Hemiconvulsion-hemiplegia-epilepsy syndrome in a child with pre-existing cerebral pathology

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