New insights into the physiology and pathophysiology of the atypical sodium leak channel NALCN.

Cell excitability and its modulation by hormones and neurotransmitters involve the concerted action of a large repertoire of membrane proteins, especially ion channels. Unique complements of coexpressed ion channels are exquisitely balanced against each other in different excitable cell types, establishing distinct electrical properties that are tailored for diverse physiological contributions, and dysfunction of any component may induce a disease state. A crucial parameter controlling cell excitability is the resting membrane potential (RMP) set by extra- and intracellular concentrations of ions, mainly Na+, K+, and Cl-, and their passive permeation across the cell membrane through leak ion channels. Indeed, dysregulation of RMP causes significant effects on cellular excitability. This review describes the molecular and physiological properties of the Na+ leak channel NALCN, which associates with its accessory subunits UNC-79, UNC-80, and NLF-1/FAM155 to conduct depolarizing background Na+ currents in various excitable cell types, especially neurons. Studies of animal models clearly demonstrate that NALCN contributes to fundamental physiological processes in the nervous system including the control of respiratory rhythm, circadian rhythm, sleep, and locomotor behavior. Furthermore, dysfunction of NALCN and its subunits is associated with severe pathological states in humans. The critical involvement of NALCN in physiology is now well established, but its study has been hampered by the lack of specific drugs that can block or agonize NALCN currents in vitro and in vivo. Molecular tools and animal models are now available to accelerate our understanding of how NALCN contributes to key physiological functions and the development of novel therapies for NALCN channelopathies.

Cenobamate in patients with highly refractory focal epilepsy: A retrospective real-world study.

PURPOSE: To determine the effectiveness and safety outcomes of cenobamate in a cohort of patients with highly refractory focal epilepsy in routine clinical practice. METHODS: Observational, retrospective, phase 4 study on subjects receiving cenobamate in three Spanish centers. The primary endpoint was the retention rate at the last follow-up. The main secondary endpoints were the 50%-responder  and seizure-free rates at three months and the last follow-up. Other secondary endpoints were Global Clinical Impressions-Improvement (CGI-I) scores and treatment-emergent adverse events (TEAEs). RESULTS: Fifty-one patients with highly refractory focal epilepsy with 24.7 years of disease evolution, ten previously tried ASM, and a 23.5% of previous epilepsy surgery were included. The retention rate at the last follow-up was 80.4%. The 50% responder rate in focal seizures at three months was 56.5% (median reduction per month 51%, 0-74.6; p < 0.0001) and in focal to bilateral tonic-clonic seizures was 63.6% (median reduction per month 89%, 0-100; p = 0.022). A total of 54.3% of subjects reported a reduction in the intensity of focal seizures, and 66% manifested clinically significant satisfaction. Cenobamate allowed a significant decrease in concomitant ASM, especially sodium channel blockers. TEAEs were reported in 43.1% of individuals, 85% of whom resolved or improved, with no new safety findings. CONCLUSION: In this analysis of patients with highly refractory focal epilepsy treated with cenobamate according to standard clinical practice, there was evidence of a high reduction in both seizure frequency and intensity, with a manageable safety profile.

Malignant Left Atrial Appendage Morphology: Current Classification vs H-L System.

INTRODUCTION: In previous studies the risk of stroke recurrence has been associated with the left atrial appendage (LAA) morphology (non-chicken wing (NCW)), knowing those with a greater risk as malignant LAA. Recently, a simpler morphological classification has been suggested with two categories: Low-risk (LAA-L) and High-risk (LAA-H); which could be easier to apply and may correlate better with the risk of embolic stroke. METHODS: Retrospective analysis from a registry of patients with recurrent cardioembolic strokes despite appropriate anticoagulant therapy, in which LAA morphology was studied with cardiac CT scan. LAA morphology was classified according to the four current categories and H-L morphology by the same cardiologist. Other variables associated with a high risk of stroke were also assessed, such as CHA2DS2-VASc score and left atrial (LA) size. RESULTS: Twenty-six cases were included in the analysis. We identified 22 (84.6%) chicken wing (CW), 1 (3.8%) windsock and 3 (11.5%) cactus by the current classification system, while 15 (57.7%) were classified as LAA-H and 11 (42.3%) as LAA-L by the new system. Half of the 22 cases with CW morphology were considered LAA-H, whereas all NCW were also classified as LAA-H. LA diameter and area were significantly higher in cases with LAA-H morphology (p=0.03 and 0.014), and also in those CW and LAA-H, compared to those CW with LAA-L (p=0.035). CONCLUSIONS: With this new classification system more than half of the cases of our malignant LAAs were classified as high-risk morphology. This morphology was also associated with an increased LA size.

Does the Country Make a Difference in Impulse Control Disorders? A Systematic Review.

BACKGROUND: Impulse control disorders (ICDs) have an increased frequency in patients with Parkinson's disease (PD), mainly because of treatment with dopamine agonists (DA). Factors related with the country of origin (culture, economy, healthcare politics) may impact phenomenology. OBJECTIVES: To explore phenomenology of ICDs depending on the country. METHODS: A systematic review following PRISMA guidelines was performed using Pubmed database. Articles published up to 2018 in which the prevalence of ICDs was analyzed were selected. RESULTS: Thirty-two studies from 22 countries worldwide were included. The highest prevalence of ICDs in each continent was found in UK (59%), USA (39.1%) and India (31.6%). Frequency of ICDs was higher in those studies with lower mean age, higher proportion of males, whenever a screening instrument was used and whenever prescription of DAs was more common. Prevalence of ICDs was higher in Western countries compared to Asian countries (20.8% vs. 12.8%, P < 0.001) as it was the proportion of patients treated with DAs (66% vs. 48.2%, P < 0.001). Hypersexuality was the most common ICD overall (up to 23.8%). The highest frequencies of compulsive buying and eating were found in Western countries. Gambling was less commonly diagnosed, but prevalence was relevant Japan (14%). CONCLUSION: We observed a tendency towards a different ICD profile in different geographical areas, which may be attributable to socio-economical, cultural or political influences in the phenomenology of these disorders. Acknowledging these differences could help their early detection, which is critical for prognosis.