Cerebral Venous Sinus Thrombosis in a 19 Year Old Female With Ulcerative Colitis: Long Term Follow-up and Review From the Literature

Background: Cerebral venous sinus thrombosis is a rare complication of ulcerative colitis. Case presentation: We present a case report of a 19-year-old female patient with ulcerative colitis, who developed superior sagittal sinus thrombosis with haemorrhagic transformation. Despite the initial treatment with anticoagulant therapy, the patient became comatose, with symptomatic epileptic seizures and compromised cardiorespiratory function. She was transferred to the ICU and put on life-support for 3 weeks. She gradually improved and was discharged on low-molecular weight heparin and antiepileptic therapy. Oral anticoagulant therapy with warfarin was started 6 months later, when the subsequent D-dimers normalized. In the follow-up period, the patient experienced another series of symptomatic epileptic seizures and poorly regulated INRs. Therefore, antiepileptic and anticoagulation therapies were changed to oxcarbazepine and rivaroxaban. Conclusion: Physicians should be aware that treatment of cerebral venous sinus thrombosis with haemorrhagic transformation in a patient with ulcerative colitis is very challenging and demanding. These patients need to be closely monitored for possible complications that might arise due to the concomitant presence of both diseases and possible drug interactions

Dissecting The Tissue-Specific Contributions To Seizures, Cardiorespiratory Dysfunction, And Sudden Death In The Kv1.1 Mouse Model Of Epilepsy Using Conditional Knockout Approaches

Sudden unexpected death in epilepsy (SUDEP), the primary cause of mortality in epilepsy, remains poorly understood. Studies suggest seizures may trigger dangerous signals affecting the heart and lungs leading to collapse and death. The Kv1.1 deficiency mouse model mirrors clinical SUDEP cases, showing spontaneous seizures, cardiorespiratory issues, and premature death. However, this model lacks regional specificity in Kv1.1 deletion, hindering insights into SUDEP’s mechanisms and anatomical substrates. This dissertation employs three distinct conditional knockout (cKO) techniques to investigate the individual roles for the forebrain, brainstem, and heart in SUDEP related phenotypes. The findings reveal that the forebrain alone can trigger spontaneous seizures and premature death. Additionally, the brainstem may play a significant role in regulating blood oxygen levels and may show gender differences in respiratory measures. Lastly, Kv1.1 in the heart is essential for cardiomyocyte action potential repolarization but does not significantly impact overall cardiac function measured in mice. This research highlights how distinct brain circuits contribute to SUDEP mechanisms, providing insights specifically for researchers using the Kv1.1 deficiency model as to where the crucial anatomical substrates may be found in future studies

Neuroimaging of Sudden Unexpected Death in Epilepsy (SUDEP)

BACKGROUND: Sudden unexpected death in epilepsy (SUDEP) is the leading cause of premature death among people with epilepsy. The precise mechanisms underlying SUDEP remain elusive, though work so far demonstrates a potential centrally mediated event in which autonomic, respiratory and/or arousal processes fail to recover following a significant seizure. Neuroimaging enables non-invasive assessment of the structural and functional architecture among sites and networks involved in regulating such processes; damage or alterations may indicate a central predisposition in those at high-risk and who suffer SUDEP, and provide non-invasive biomarkers. // METHODS: In this thesis, structural and functional imaging techniques were employed to address this possibility. Both retrospective investigations of those who succumbed to SUDEP, and prospective studies of those at high-risk, were performed. Voxel-based morphometry, volumetry and resting-state functional magnetic resonance imaging (RS-fMRI) network analysis techniques were utilised to identify and characterise brain structural and functional alterations relative to low-risk subjects and controls. // RESULTS: Brain morphometric and volumetric alterations among sites involved in cardiorespiratory regulation and recovery were found in those who later suffered SUDEP and in matched, living individuals at high risk. Prospective work revealed similar, and additional, structural alterations in those at high-risk which were associated with the extent of seizure-related hypoxemia; notably among the thalamus, periaqueductal grey (PAG), medulla, vermis and hippocampus. Network analysis of functional imaging data revealed disturbed patterns of connectivity in high-risk temporal lobe epilepsy (TLE) patients, and altered functional organisation in confirmed cases of SUDEP, among regulatory brain sites as well as the whole brain. // CONCLUSIONS: Structural and resting state functional connectivity disturbances were found in patients who suffered SUDEP, and those at elevated risk. Injury and connectivity disturbances may indicate damage or dysfunction within sites and networks involved central regulatory processes, which could facilitate SUDEP. However, further work is required to elucidate the precise mechanisms of volume and functional connectivity alterations, and to provide firm links between centrally mediated autonomic and respiratory dysfunction, SUDEP and related imaging findings. A more immediate use for the imaging outcomes revealed here may rest with the development of non-invasive biomarkers, which may one day assist in identifying those at risk and evaluating individual risk for SUDEP based on injury to brain sites or altered functional networks

ALTERATIONS IN GABAERGIC NTS NEURON FUNCTION IN ASSOCIATION WITH TLE AND SUDEP

Epilepsy is a neurological disorder that is characterized by aberrant electrical activity in the brain resulting in at least two unprovoked seizures over a period longer than 24 hours. Approximately 60% of individuals with epilepsy are diagnosed with temporal lobe epilepsy (TLE) and about one third of those individuals do not respond well to anti-seizure medications. This places those individuals at high risk for sudden unexpected death in epilepsy (SUDEP). SUDEP is defined as when an individual with epilepsy, who is otherwise healthy, dies suddenly and unexpectedly for unknown reasons. SUDEP is one of the leading causes of death in individuals with acquired epilepsies (i.e. not due to genetic mutations), such as TLE. Previous studies utilizing genetic models of epilepsy have suggested that circuitry within the vagal complex of the brainstem may play a role in SUDEP risk. Gamma-aminobutyric acid (GABA) neurons of the nucleus tractus solitarius (NTS) within the vagal complex receive, filter, and modulate cardiorespiratory information from the vagus nerve. GABAergic NTS neurons then project to cardiac vagal motor neurons, eventually effecting parasympathetic output to the periphery. In this study, a mouse model of TLE was used to assess the effect of epileptogenesis on GABAergic NTS neuron function and determine if functional alterations in these neurons impact SUDEP risk. It was discovered that mice with TLE (i.e. TLE mice) have significantly increased mortality rates compared to control animals, suggesting that SUDEP occurs in this model. Using whole cell electrophysiology synaptic and intrinsic properties of GABAergic NTS neurons were investigated in TLE and control mice. Results suggest that during epileptogenesis, GABAergic NTS neurons become hyperexcitable, potentially due to a reduction in A-type potassium channel current and increased excitatory synaptic input. Increases in hyperexcitability have been shown to be associated with an increased risk of spreading depolarization and action potential inactivation leading to neuronal quiescence. This may lead to a decreased inhibition of parasympathetic tone, causing cardiorespiratory collapse and SUDEP in TLE

The end is just the beginning:Unraveling the postictal state

Epilepsy is one of the most common neurological disorders worldwide. Postictal symptoms, occurring after seizures, often form a great burden for patients and their caregivers. Approximately one-third of patients do not achieve seizure freedom with proper treatment (i.e., antiepileptic medication or surgical removal of epileptic tissue). These patients suffer from the seizure aftermath each time they have a seizure. Until today, it is unclear how we can treat the postictal state effectively. Promising findings from animal studies showed that acetaminophen (in The Netherlands better known as ‘paracetamol’) or nimodipine (vasodilator) could improve postictal symptoms in rats. We highlight that a clear definition for the postictal state was still lacking, which is why we provided a new definition that includes its manifestation (i.e., clinical and electroencephalography [EEG]) as well as temporal variability. ECT appears to be a useful human model to investigate seizures and postictal states because clinical and EEG characteristics (i.e., spatiotemporal dynamics) show sufficient similarities between both epilepsy and ECT patients. With ECT, ictal and postictal phenomena can be studied in a well-controlled environment, increasing practical feasibility of clinical studies. We describe that the postictal EEG shows a clear pattern of frequencies that return to baseline levels at approximately 1h after the seizure, which depends on seizure duration. Longer clinical reorientation time and repeated exposure to seizures are associated with longer postictal EEG recovery.We examined postictal cerebral blood flow, measured with arterial spin labeling magnetic resonance imaging (ASL-MRI), and show clear patterns of hypoperfusion in some patients, while in others, discrete local hyperperfusion is seen. These opposite patterns depend on seizure duration. Using functional MRI, we show that postictal mean network connectivity strength decreases in the left central executive network and in the auditory network compared to baseline and controlled for network connectivity changes in healthy controls. Finally, with our prospective clinical trial with randomized three-condition cross-over design, we fail to replicate findings from animal models, possibly because our chosen doses of pre-ECT administered acetaminophen or nimodipine (much lower than in the animal studies) do not improve postictal EEG recovery, clinical reorientation time and postictal ASL-MRI perfusion

The heart of epilepsy: Cardiac comorbidity and sudden death

The research described in this thesis aims to increase understanding of cardiac comorbidities and sudden unexpected death in epilepsy (SUDEP). People with epilepsy have a three-fold increased risk of dying prematurely compared to the general population. Common contributors to this are cardiovascular comorbidities, of which I provide an overview. Cardiovascular conditions and epilepsy can both lead to transient loss of consciousness (TLOC) with overlapping semiology. Particularly, myoclonic jerks which are commonly observed during syncope can be mistaken for signs of epilepsy. A misdiagnosis with detrimental consequences. I provide evidence that a careful analysis of motor phenomena can distinguish the two conditions. SUDEP is the commonest direct epilepsy-related premature death (UK >500 people/year). It typically occurs following convulsive seizures (CS). Most victims are found prone and some suggested people should sleep supine. I assessed video-EEG recordings of 180 CS and demonstrated peri-ictal positions often change, and most ending prone turned during CS. Sleeping supine is thus unlikely to prevent a postictal prone position and reduce risk of SUDEP. Pathomechanisms underlying SUDEP are likely a combination of interacting cardiorespiratory and autonomic factors. People with Dravet syndrome (DS) have a particular high SUDEP risk. I show that 49% of reported deaths in DS are SUDEP cases, most <10 years (78%). In DS, SCN1A mutations are mostly found, encoding a sodium channel expressed in brain and heart. DS mouse models suggest a key role for peri-ictal cardiac arrhythmias in SUDEP. I conducted a multicentre observational study and recorded 547 seizures in 45 DS participants. No major peri-ictal arrhythmias were found. Peri-ictal QTc-lengthening was, however, more common in DS than controls. This may reflect unstable repolarisation and increased propensity for arrhythmias. Prospective data to determine whether these peri-ictal variables can predict SUDEP risk is warranted

The spatiotemporal dynamics of human focal seizures

Spontaneous human focal seizures can present with a plethora of behavioral manifestations that vary according to the affected cortical regions; however, several key features have been consistently observed. During my doctoral studies, I applied both theoretical and experimental methods to study mechanisms underpinning these consistently seen dynamics. I first analyzed human intracranial EEG recordings, describing statistical methods for measuring their electrophysiological signatures. I next proposed several neurophysiological hypotheses that could explain seizure dynamics and verified them in rodent seizure models. Finally, a computational model was developed, successfully explaining how the complex spatiotemporal evolution of focal seizures emerges from simple neurophysiological principles. In Chapter 1, the long-standing behavioral manifestations and the most up-to-date electrophysiology findings are reviewed. This section details the inspiration for the studies reported in the subsequent chapters. In Chapter 2, I describe several statistical methods for estimating traveling wave velocities. I show most ictal discharges can be described as traveling waves whose velocities contain rich information about the stages of seizure evolution. I compare performance of various statistical methods and propose a robust approach to boost the quality of each method’s estimation results. In Chapter 3, I show how inhibition modulates seizure propagation patterns. Surround inhibition spatially restrains focal seizures and masks excitatory projections of ictal activities. When compromised, two patterns of seizure propagation emerge according to the position of inhibition defects relative to the ictal focus. I show that two distant ictal foci can communicate via physiological connectivity without any chronic rewiring processes – confirming the existence of long-range propagation pathways that could lead to epileptic network formation. In Chapter 4, I show that thalamic inputs might be necessary for interictal epileptiform discharges (IEDs). The relative positions between IEDs and ictal foci indicate that surround inhibition, shown in the previous chapter, can be exhausted by repetitive exposure to ictal projections. In Chapter 5, I propose a neural network model that can explain both long-standing behavioral observations of seizures and account for the most up-to-date electrophysiological recordings of spontaneous human focal seizures. The model relies on few assumptions, all of which are proved or supported in earlier chapters of this thesis. The model explains phasic evolution of seizure dynamics – how the commonly observed patterns arise from simple neurophysiological principles, as well as seizure onset subtypes, traveling wave directions and speeds. The model also predicts how spontaneous seizures might arise from synaptic plasticity. The chapter ends with a discussion of the model’s implications and future work. The thesis is organized in a way that each chapter can be read independently, with Chapter 5 summarizing the central theory spanning the whole study. Each chapter is also tightly linked to a clinically relevant question. In sum, the dissertation’s goal is to provide an in-principle understanding of focal seizure dynamics. With rapid advancement of clinical and experimental tools, I believe this work provides a roadmap for future therapies for epilepsy patients

Epileptic Seizures are Reduced by Autonomic Biofeedback Therapy Through Enhancement of Fronto-limbic Connectivity: A Controlled Trial and Neuroimaging Study.

BACKGROUND: Thirty-percent of patients with epilepsy are drug-resistant, and might benefit from effective noninvasive therapeutic interventions. Evidence is accumulating on the efficacy of autonomic biofeedback therapy using galvanic skin response (GSR; an index of sympathetic arousal) in treating epileptic seizures. This study aimed to extend previous controlled clinical trials of autonomic biofeedback therapy with a larger homogeneous sample of patients with temporal lobe epilepsy. In addition, we used neuroimaging to characterize neural mechanisms of change in seizure frequency following the therapy. METHODS: Forty patients with drug-resistant temporal lobe epilepsy (TLE) (age: 18 to 70years old), on stable doses of anti-epileptic medication, were recruited into a controlled and parallel-group trial from three screening centers in the UK. Patients were allocated to either an active intervention group, who received therapy with GSR biofeedback, or a control group, who received treatment as usual. Allocation to the group was informed, in part, by whether patients could travel to attend repeated therapy sessions (non-randomized). Measurement of outcomes was undertaken by an assessor blinded to the patients' group membership. Resting-state functional and structural MRI data were acquired before and after one month of therapy in the therapy group, and before and after a one-month interval in the control group. The percentage change of seizure frequency was the primary outcome measure. The analysis employed an intention-to-treat principle. The secondary outcome was the change in default mode network (DMN) and limbic network functional connectivity tested for effects of therapy. The trial was registered with the National Institute for Health Research (NIHR) portfolio (ID 15967). FINDINGS: Data were acquired between May 2014 and October 2016. Twenty participants were assigned to each group. Two patients in the control group dropped out before the second scan, leaving 18 control participants. There was a significant difference in reduction of seizure frequency between the therapy and control groups (p50%. Neuroimaging analysis revealed that post-therapy seizure reduction was linearly correlated with enhanced functional connectivity between right amygdala and both the orbitofrontal cortex (OFC) and frontal pole (FP). INTERPRETATION: Our clinical study provides evidence for autonomic biofeedback therapy as an effective and potent behavioral intervention for patients with drug-resistant epilepsy. This approach is non-pharmacological, non-invasive and seemingly side-effect free

Modern sedative agents and techniques used in dentistry for patients with special needs: A review

According to the World Health Organisation, approximately 1.3 billion people worldwide experience substantial disability due to physical, mental or sensory impairment. People with special needs require special consideration and more time or altered delivery methods when receiving dental treatments. Various factors, such as patients' lack of cooperation, cognitive impairment and complex medical status, may lead dental practitioners to recommend conscious sedation. Several pharmacological agents and administrative routes are available, which achieve varying levels of sedation ranging from minimal to deep. Pre-operative assessment and careful case selection are necessary to determine the appropriate sedative agent, route of administration and level of sedation for each patient. Thus, a thorough understanding of the pharmacokinetics, risks and benefits, and implications of various sedatives available for PSN is essential to achieve the desired clinical outcomes. This review critically presents the considerations associated with the use of various sedative agents for PSN in dentistry. Considerations include patients' pre-anaesthesia medical comorbidities, cardiorespiratory adverse effects and cooperativeness, and the viable alternative treatment modalities

Characterization and processing of novel neck photoplethysmography signals for cardiorespiratory monitoring

Epilepsy is a neurological disorder causing serious brain seizures that severely affect the patients' quality of life. Sudden unexpected death in epilepsy (SUDEP), for which no evident decease reason is found after post-mortem examination, is a common cause of mortality. The mechanisms leading to SUDEP are uncertain, but, centrally mediated apneic respiratory dysfunction, inducing dangerous hypoxemia, plays a key role. Continuous physiological monitoring appears as the only reliable solution for SUDEP prevention. However, current seizure-detection systems do not show enough sensitivity and present a high number of intolerable false alarms. A wearable system capable of measuring several physiological signals from the same body location, could efficiently overcome these limitations. In this framework, a neck wearable apnea detection device (WADD), sensing airflow through tracheal sounds, was designed. Despite the promising performance, it is still necessary to integrate an oximeter sensor into the system, to measure oxygen saturation in blood (SpO2) from neck photoplethysmography (PPG) signals, and hence, support the apnea detection decision. The neck is a novel PPG measurement site that has not yet been thoroughly explored, due to numerous challenges. This research work aims to characterize neck PPG signals, in order to fully exploit this alternative pulse oximetry location, for precise cardiorespiratory biomarkers monitoring. In this thesis, neck PPG signals were recorded, for the first time in literature, in a series of experiments under different artifacts and respiratory conditions. Morphological and spectral characteristics were analyzed in order to identify potential singularities of the signals. The most common neck PPG artifacts critically corrupting the signal quality, and other breathing states of interest, were thoroughly characterized in terms of the most discriminative features. An algorithm was further developed to differentiate artifacts from clean PPG signals. Both, the proposed characterization and classification model can be useful tools for researchers to denoise neck PPG signals and exploit them in a variety of clinical contexts. In addition to that, it was demonstrated that the neck also offered the possibility, unlike other body parts, to extract the Jugular Venous Pulse (JVP) non-invasively. Overall, the thesis showed how the neck could be an optimum location for multi-modal monitoring in the context of diseases affecting respiration, since it not only allows the sensing of airflow related signals, but also, the breathing frequency component of the PPG appeared more prominent than in the standard finger location. In this context, this property enabled the extraction of relevant features to develop a promising algorithm for apnea detection in near-real time. These findings could be of great importance for SUDEP prevention, facilitating the investigation of the mechanisms and risk factors associated to it, and ultimately reduce epilepsy mortality.Open Acces