Seizure-like episodes and EEG abnormalities in patients with long QT syndrome

Neurocardiac pathologies associated with potassium channelopathies

Voltage-gated potassium channels are expressed throughout the human body and are essential for physiological functions. These include delayed rectifiers, A-type channels, outward rectifiers, and inward rectifiers. They impact electrical function in the heart (repolarization) and brain (repolarization and stabilization of the resting membrane potential). KCNQx and KCNHx encode Kv7.x and Kv11.x proteins, which form delayed rectifier potassium channels. KCNQx and KCNHx channelopathies are associated with both cardiac and neuronal pathologies. These include electrocardiographic abnormalities, cardiac arrhythmias, sudden cardiac death (SCD), epileptiform discharges, seizures, bipolar disorder, and sudden unexpected death in epilepsy (SUDEP). Due to the ubiquitous expression of KCNQx and KCNHx channels, abnormalities in their function can be particularly harmful, increasing the risk of sudden death. For example, KCNH2 variants have a dual role in both cardiac and neuronal pathologies, whereas KCNQ2 and KCNQ3 variants are associated with severe and refractory epilepsy. Recurrent and uncontrolled seizures lead to secondary abnormalities, which include autonomics, cardiac electrical function, respiratory drive, and neuronal electrical activity. Even with a wide array of anti-seizure therapies available on the market, one-third of the more than 70 million people worldwide with epilepsy have uncontrolled seizures (i.e., intractable/drug-resistant epilepsy), which negatively impact neurodevelopment and quality of life. To capture the current state of the field, this review examines KCNQx and KCNHx expression patterns and electrical function in the brain and heart. In addition, it discusses several KCNQx and KCNHx variants that have been clinically and electrophysiologically characterized. Because these channel variants are associated with multi-system pathologies, such as epileptogenesis, Kv7 channel modulators provide a potential anti-seizure therapy, particularly for people with intractable epilepsy. Ultimately an increased understanding of the role of Kv channels throughout the body will fuel the development of innovative, safe, and effective therapies for people at a high risk of sudden death (SCD and SUDEP).

Antiseizure medication and SUDEP - a need for unifying methodology in research

The risk of sudden unexpected death in epilepsy (SUDEP) increases with the frequency of generalized tonic-clonic seizures. Carbamazepine (CBZ) and lamotrigine (LTG) have been suggested to increase the risk. However, the prevailing viewpoint is that the choice of antiseizure medication (ASM) does not influence the occurrence. We have explored the approach to addressing this question in relevant studies to evaluate the validity of the conclusions reached. A systematic search was performed in PubMed to identify all controlled studies on SUDEP risk in individuals on CBZ or LTG. Studies were categorized according to whether idiopathic generalized epilepsy (IGE) or females were considered separately, and whether data were adjusted for seizure frequency. Eight studies on CBZ and six studies on LTG were identified. For CBZ, one study showed a significantly increased risk of SUDEP without adjustment for seizure frequency. Another study found significantly increased risk after statistical adjustment for seizure frequency and one study found increased risk with high blood levels. Five other studies found no increase in risk. For LTG, one study showed a significantly increased risk in patients with IGE as opposed to focal epilepsy, and another study showed a significantly increased risk in females. None of the subsequent studies on LTG and none of the studies on CBZ considered females with IGE separately. Taken together the available studies suggest that LTG, and possibly CBZ, may increase occurrence of SUDEP when used in females with IGE. Additional studies with sub-group analysis of females with IGE are needed.

Shades of a channelopathy-Hypoperfusion, excitability, or both: A case video

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Seizure as the clinical presentation of massive pulmonary embolism: Case report and literature review

Massive pulmonary embolism (MPE) is a high-risk medical emergency. Seizure as the clinical presentation of MPE is extremely rare, and to our knowledge, there have been no reports on successful percutaneous, catheter-based treatment of MPE presenting with new-onset seizures and cardiac arrest. In this report, we discuss the case of a 64-year-old woman who presented with an episode of seizure that lasted 5 h. Seizure occurred four times within 12 h after arrival at the hospital, and in the end, she sustained a cardiac arrest. The patient had no past history of seizure or cardiopulmonary disease. Bilateral MPE was detected by a computed tomography pulmonary angiogram, and she was successfully treated with percutaneous, catheter-directed anticoagulant therapy. Pulmonary embolism-related seizures are more difficult to diagnose and have higher mortality rates than seizures. MPE should be suspected in patients presenting with new-onset seizures and hemodynamic instability.

Episodic Memory Dysfunction and Effective Connectivity in Adult Patients With Newly Diagnosed Nonlesional Temporal Lobe Epilepsy

Objective

Epilepsy is associated with both changes in brain connectivity and memory function, usually studied in the chronic patients. The aim of this study was to explore the presence of connectivity alterations measured by EEG in the parietofrontal network in patients with temporal lobe epilepsy (TLE), and to examine episodic memory, at the time point of diagnosis.

Methods

The parietofrontal network of newly diagnosed patients with TLE (N = 21) was assessed through electroencephalography (EEG) effective connectivity and compared with that of matched controls (N = 21). Furthermore, we assessed phenomenological aspects of episodic memory in both groups. Association between effective connectivity and episodic memory were assessed through correlation.

Results

Patients with TLE displayed decreased episodic (p ≤ 0.001, t = −5.18) memory scores compared with controls at the time point of diagnosis. The patients showed a decreased right parietofrontal connectivity (p = 0.03, F = 4.94) compared with controls, and significantly weaker connectivity in their right compared with their left hemisphere (p = 0.008, t = −2.93). There were no significant associations between effective connectivity and episodic memory scores.

Conclusions

We found changes in both memory function and connectivity at the time point of diagnosis, supporting the notion that TLE involves complex memory functions and brain networks beyond the seizure focus to strongly interconnected brain regions, already early in the disease course. Whether the observed connectivity changes can be interpreted as functionally important to the alterations in memory function, it remains speculative.

Neurological complications of syncope and sudden cardiac arrest

Syncope is very common and usually comes with enough warning for the person to assume a safer position rather than fall in a potentially dangerous way. Syncope may be associated with pregnancy, for example, but we rarely encounter significant injury related to the potential for an associated fall. In the elderly, however, there are often comorbid factors such as delayed reaction time and other aspects of cognitive impairment, along with gait instability, that can affect the defensive reflexes to the point that brain injury, including subdural or epidural hematoma, is not uncommonly encountered. Sudden syncope without warning can also have both neurological and general physical implications in terms of driving safety, safety operating potentially dangerous equipment or exposure to heights as well as the potential impact for drowning or near-drowning while swimming or taking a bath. Sudden death, from whatever the mechanism, implies cerebral hypoperfusion with the potential consequences of hypoxic-ischemic brain injury.

Overt long QT syndrome in children presenting with seizure disorders in Pakistan

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Sudden death in a patient with long QT syndrome presenting with an epileptic phenotype

Patients with epilepsy suffer from a higher mortality rate than the general population, a portion of which is not due to epilepsy itself or comorbid conditions. Sudden unexpected death in epilepsy (SUDEP) is a common but poorly understood cause of death in patients with intractable epilepsy and often afflicts younger patients. The pathophysiology of SUDEP is poorly defined but does not appear to be related to prolonged seizure activity or resultant injury. Interestingly, a subset of patients with confirmed long QT syndrome (LQTS) present with a seizure phenotype and may have concurrent epilepsy. In this case, we present a patient who initially presented with a seizure phenotype. Further workup captured PMVT on an outpatient event monitor, and the patient was subsequently diagnosed with LQTS1. A substantial number of patients with LQTS initially present with a seizure phenotype. These patients may represent a subset of SUDEP cases resulting from ventricular arrhythmias. Appropriate suspicion for ventricular arrhythmias is necessary for proper arrhythmia evaluation and management in patients presenting with epilepsy.

Prevention of sudden unexpected death in epilepsy: current status and future perspectives

Introduction: Sudden unexpected death in epilepsy (SUDEP) affects about 1 in 1000 people with epilepsy, and even more in medically refractory epilepsy. As most people are between 20 and 40 years when dying suddenly, SUDEP leads to a considerable loss of potential life years. The most important risk factors are nocturnal and tonic-clonic seizures, underscoring that supervision and effective seizure control are key elements for SUDEP prevention. The question of whether specific antiepileptic drugs are linked to SUDEP is still controversially discussed. Knowledge and education about SUDEP among health-care professionals, patients, and relatives are of outstanding importance for preventive measures to be taken, but still poor and widely neglected.Areas covered: This article reviews epidemiology, pathophysiology, risk factors, assessment of individual SUDEP risk and available measures for SUDEP prevention. Literature search was done using Medline and Pubmed in October 2019.Expert opinion: Significant advances in the understanding of SUDEP were made in the last decade which allow testing of novel strategies to prevent SUDEP. Promising current strategies target neuronal mechanisms of brain stem dysfunction, cardiac susceptibility for fatal arrhythmias, and reliable detection of tonic-clonic seizures using mobile health technologies.Abbreviations: AED, antiepileptic drug; CBZ, carbamazepine; cLQTS, congenital long QT syndrome; EMU, epilepsy monitoring unit; FBTCS, focal to bilateral tonic-clonic seizures; GTCS, generalized tonic-clonic seizures; ICA, ictal central apnea; LTG, lamotrigine; PCCA, postconvulsive central apnea; PGES, postictal generalized EEG suppression; SRI, serotonin reuptake inhibitor; SUDEP, sudden unexpected death in epilepsy; TCS, tonic-clonic seizures.