Cannabidiol attenuates seizure susceptibility and behavioural deficits in adult CDKL5R59X knock-in mice.

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is caused by a loss-of-function mutation in CDKL5 gene, encoding a serine-threonine kinase highly expressed in the brain. CDD manifests with early-onset epilepsy, autism, motor impairment and severe intellectual disability. While there are no known treatments for CDD, the use of cannabidiol has recently been introduced into clinical practice for neurodevelopmental disorders. Given the increased clinical utilization of cannabidiol, we examined its efficacy in the CDKL5R59X knock-in (R59X) mice, a CDD model based on a human mutation that exhibits both lifelong seizure susceptibility and behavioural deficits. We found that cannabidiol pre-treatment rescued the increased seizure susceptibility in response to the chemoconvulsant pentylenetetrazol (PTZ), attenuated working memory and long-term memory impairments, and rescued social deficits in adult R59X mice. To elucidate a potential mechanism, we compared the developmental hippocampal and cortical expression of common endocannabinoid (eCB) targets in R59X mice and their wild-type littermates, including cannabinoid type 1 receptor (CB1R), transient receptor potential vanilloid type 1 (TRPV1) and 2 (TRPV2), G-coupled protein receptor 55 (GPR55) and adenosine receptor 1 (A1R). Many of these eCB targets were developmentally regulated in both R59X and wild-type mice. In addition, adult R59X mice demonstrated significantly decreased expression of CB1R and TRPV1 in the hippocampus, and TRPV2 in the cortex, while TRPV1 was increased in the cortex. These findings support the potential for dysregulation of eCB signalling as a plausible mechanism and therapeutic target in CDD, given the efficacy of cannabidiol to attenuate hyperexcitability and behavioural deficits in this disorder.

What are the predominant predictors of seizure relapse following discontinuation of anti-seizure medication in epileptic children?

OBJECTIVE: The aim of the study was to identify the predominant predictors of seizure relapse following discontinuation of ASM in epileptic children. METHODS: The study cohort consisted of 403 epileptic children who had a withdrawal process of ASM (monotherapy: 344; dual therapy or polytherapy: 59) after at least a 2-year seizure-free period. Patients were categorized if they had a well-defined epileptic syndrome. Epileptic children with ongoing ketogenic diet, vagal nerve stimulation, or surgery were excluded from the cohort due to the additional withdrawal process related to other therapy modalities. RESULTS: The cohort's seizure relapse rate was 12.7% (51/403). The highest rates of seizure relapse were defined for genetic etiology at 25% and structural etiology at 14.9%. An epilepsy syndrome was defined in 183 of 403 children (45.4%). There was no difference in the seizure relapse rate between the subgroups of well-defined epileptic syndromes; 13.8% for self-limited focal epileptic syndromes, 11.7% for developmental and epileptic encephalopathies, and 7.1% for generalized epileptic syndromes. Five predictors were defined as the most powerful predictors of seizure relapse in univariate analysis: age at epilepsy diagnosis >2 years (hazard ratio [HR]: 1.480; 95% confidence interval [CI]: 1.134-1.933), defined etiology (HR: 1.304; 95% CI: 1.003-1.696), focal seizure (HR: 1.499; 95% CI: 1.209-1.859), ≤3 months duration of the withdrawal process (HR: 1.654; 95% CI: 1.322-2.070), and a history of neonatal encephalopathy with or without seizures (HR: 3.140; 95% CI: 2.393-4.122). In multivariate analysis, the main predictor of seizure relapse was a history of neonatal encephalopathy with or without seizures (HR: 2.823; 95% CI: 2.067-3.854). SIGNIFICANCE: The duration of seizure freedom before discontinuation of ASM was not a predominant risk factor for seizure relapse: 2-3 years versus >3 years. The predictive values of five predictors of seizure relapse rate should be evaluated for patients with different epilepsy subgroups.

Genotype-phenotype correlations in SCN8A-related disorders reveal prognostic and therapeutic implications.

We report detailed functional analyses and genotype-phenotype correlations in 392 individuals carrying disease-causing variants in SCN8A, encoding the voltage-gated Na+ channel Nav1.6, with the aim of describing clinical phenotypes related to functional effects. Six different clinical subgroups were identified: Group 1, benign familial infantile epilepsy (n = 15, normal cognition, treatable seizures); Group 2, intermediate epilepsy (n = 33, mild intellectual disability, partially pharmaco-responsive); Group 3, developmental and epileptic encephalopathy (n = 177, severe intellectual disability, majority pharmaco-resistant); Group 4, generalized epilepsy (n = 20, mild to moderate intellectual disability, frequently with absence seizures); Group 5, unclassifiable epilepsy (n = 127); and Group 6, neurodevelopmental disorder without epilepsy (n = 20, mild to moderate intellectual disability). Those in Groups 1-3 presented with focal or multifocal seizures (median age of onset: 4 months) and focal epileptiform discharges, whereas the onset of seizures in patients with generalized epilepsy was later (median: 42 months) with generalized epileptiform discharges. We performed functional studies expressing missense variants in ND7/23 neuroblastoma cells and primary neuronal cultures using recombinant tetrodotoxin-insensitive human Nav1.6 channels and whole-cell patch-clamping. Two variants causing developmental and epileptic encephalopathy showed a strong gain-of-function (hyperpolarizing shift of steady-state activation, strongly increased neuronal firing rate) and one variant causing benign familial infantile epilepsy or intermediate epilepsy showed a mild gain-of-function (defective fast inactivation, less increased firing). In contrast, all three variants causing generalized epilepsy induced a loss-of-function (reduced current amplitudes, depolarizing shift of steady-state activation, reduced neuronal firing). Functional effects were known for 170 individuals. All 136 individuals carrying a functionally tested gain-of-function variant had either focal (n = 97, Groups 1-3) or unclassifiable (n = 39) epilepsy, whereas 34 individuals with a loss-of-function variant had either generalized (n = 14), no (n = 11) or unclassifiable (n = 6) epilepsy; only three had developmental and epileptic encephalopathy. Computational modelling in the gain-of-function group revealed a significant correlation between the severity of the electrophysiological and clinical phenotypes. Gain-of-function variant carriers responded significantly better to sodium channel blockers than to other anti-seizure medications, and the same applied for all individuals in Groups 1-3. In conclusion, our data reveal clear genotype-phenotype correlations between age at seizure onset, type of epilepsy and gain- or loss-of-function effects of SCN8A variants. Generalized epilepsy with absence seizures is the main epilepsy phenotype of loss-of-function variant carriers and the extent of the electrophysiological dysfunction of the gain-of-function variants is a main determinant of the severity of the clinical phenotype in focal epilepsies. Our pharmacological data indicate that sodium channel blockers present a treatment option in SCN8A-related focal epilepsy with onset in the first year of life.

Celiac Disease in Children: An Association With Drug-Resistant Epilepsy.

BACKGROUND: Neurological manifestations are commonly reported in patients with celiac disease (CD). We aimed to characterize epilepsy features in a pediatric population with CD and the effect of a gluten-free diet (GFD) on seizure burden. METHODS: A retrospective chart review was performed on pediatric patients treated at the University of Utah and Primary Children's Hospital in Salt Lake City, Utah, with both epilepsy and CD and compared with a control group with epilepsy only. RESULTS: We identified 56 patients with epilepsy and biopsy-confirmed CD (n = 36, 64%) or elevated tissue transglutaminase antibodies (tTG-Ab) without biopsy-confirmed CD (n = 20, 36%). Age- and gender-matched controls were selected from patients with epilepsy only (n = 168). Patients with biopsy-proven CD or positive tTG-Ab had high percentage of drug-resistant epilepsy (DRE) compared with the control group (P < 0.05). Age at seizure onset preceded the diagnosis of CD on average by 5.9 years for patients with DRE (P < 0.01) compared with 2.2 years for those with drug-responsive epilepsy. Adhering to a GFD reduced seizure frequency or resulted in weaning dosage or weaning off of one or more antiseizure medications in a majority of patients with DRE. CONCLUSIONS: DRE was more prevalent in pediatric patients with biopsy-confirmed CD and positive tTG-Ab compared with the control group (which included childhood epilepsy syndromes), but comparable with the prevalence of DRE in the general population. Adherence to a GFD in combination with antiseizure medications appears to reduce seizure burden for those with CD and DRE.

The severe epilepsy syndromes of infancy: A population-based study.

OBJECTIVE: To study the epilepsy syndromes among the severe epilepsies of infancy and assess their incidence, etiologies, and outcomes. METHODS: A population-based cohort study was undertaken of severe epilepsies with onset before age 18 months in Victoria, Australia. Two epileptologists reviewed clinical features, seizure videos, and electroencephalograms to diagnose International League Against Epilepsy epilepsy syndromes. Incidence, etiologies, and outcomes at age 2 years were determined. RESULTS: Seventy-three of 114 (64%) infants fulfilled diagnostic criteria for epilepsy syndromes at presentation, and 16 (14%) had "variants" of epilepsy syndromes in which there was one missing or different feature, or where all classical features had not yet emerged. West syndrome (WS) and "WS-like" epilepsy (infantile spasms without hypsarrhythmia or modified hypsarrhythmia) were the most common syndromes, with a combined incidence of 32.7/100 000 live births/year. The incidence of epilepsy of infancy with migrating focal seizures (EIMFS) was 4.5/100 000 and of early infantile epileptic encephalopathy (EIEE) was 3.6/100 000. Structural etiologies were common in "WS-like" epilepsy (100%), unifocal epilepsy (83%), and WS (39%), whereas single gene disorders predominated in EIMFS, EIEE, and Dravet syndrome. Eighteen (16%) infants died before age 2 years. Development was delayed or borderline in 85 of 96 (89%) survivors, being severe-profound in 40 of 96 (42%). All infants with EIEE or EIMFS had severe-profound delay or were deceased, but only 19 of 64 (30%) infants with WS, "WS-like," or "unifocal epilepsy" had severe-profound delay, and only two of 64 (3%) were deceased. SIGNIFICANCE: Three quarters of severe epilepsies of infancy could be assigned an epilepsy syndrome or "variant syndrome" at presentation. In this era of genomic testing and advanced brain imaging, diagnosing epilepsy syndromes at presentation remains clinically useful for guiding etiologic investigation, initial treatment, and prognostication.

Pregnenolone and pregnenolone-methyl-ether rescue neuronal defects caused by dysfunctional CLIP170 in a neuronal model of CDKL5 Deficiency Disorder.

Mutations in the X-linked cyclin-dependent kinase-like 5 (CDKL5) gene are responsible for the onset of CDKL5 Deficiency Disorder (CDD), a neurological pathology characterised by severe infantile seizures, intellectual disability, impairment of gross motor skills, sleep and gastrointestinal disturbances. CDKL5 is a serine/threonine kinase the molecular network of which is not yet fully understood. Loss of CDKL5 both in vitro and in vivo leads to altered neuronal morphology including axon specification and outgrowth, dendritic arborisation and spine morphology suggesting a link between CDKL5 and the regulation of proper cytoskeleton functioning. Recently, we found that CDKL5 regulates the binding of CLIP170 to microtubules (MT). CLIP170 is a MT-plus end tracking protein (+TIP) that associates with MTs when present in its open, active conformation. Here we present evidence suggesting CLIP170 contributes to neuronal CDKL5-dependent defects and that it represents an important novel druggable target for CDD; indeed, CLIP170 is directly targeted by the neuroactive steroid pregnenolone (PREG), which induces the active conformation of the protein thus promoting MT-dynamics. We here show that PREG and a synthetic derivative pregnenolone-methyl-ether (PME) can restore the MT association of CLIP170 and revert morphological and molecular defects in Cdkl5-KO neurons at different stages of maturation. All together, these findings identify CLIP170 as possible novel druggable target for CDKL5 related disorders providing an intriguing prospective for future disease-modifying drug-based therapies.

Cannabis for the Treatment of Epilepsy: an Update.

PURPOSE OF REVIEW: For millennia, there has been interest in the use of cannabis for the treatment of epilepsy. However, it is only recently that appropriately powered controlled studies have been completed. In this review, we present an update on the research investigating the use of cannabidiol (CBD), a non-psychoactive component of cannabis, in the treatment of epilepsy. RECENT FINDINGS: While the anticonvulsant mechanism of action of CBD has not been entirely elucidated, we discuss the most recent data available including its low affinity for the endocannabinoid receptors and possible indirect modulation of these receptors via blocking the breakdown of anandamide. Additional targets include activation of the transient receptor potential of vanilloid type-1 (TRPV1), antagonist action at GPR55, targeting of abnormal sodium channels, blocking of T-type calcium channels, modulation of adenosine receptors, modulation of voltage-dependent anion selective channel protein (VDAC1), and modulation of tumor necrosis factor alpha release. We also discuss the most recent studies on various artisanal CBD products conducted in patients with epilepsy in the USA and internationally. While a high percentage of patients in these studies reported improvement in seizures, these studies were either retrospective or conducted via survey. Dosage/preparation of CBD was either unknown or not controlled in the majority of these studies. Finally, we present data from both open-label expanded access programs (EAPs) and randomized placebo-controlled trials (RCTs) of a highly purified oral preparation of CBD, which was recently approved by the FDA in the treatment of epilepsy. In the EAPs, there was a significant improvement in seizure frequency seen in a large number of patients with various types of treatment-refractory epilepsy. The RCTs have shown significant seizure reduction compared to placebo in patients with Dravet syndrome and Lennox-Gastaut syndrome. Finally, we describe the available data on adverse effects and drug-drug interactions with highly purified CBD. While this product is overall well tolerated, the most common side effects are diarrhea and sedation, with sedation being much more common in patients taking concomitant clobazam. There was also an increased incidence of aspartate aminotransferase and alanine aminotransferase elevations while taking CBD, with many of the patients with these abnormalities also taking concomitant valproate. CBD has a clear interaction with clobazam, significantly increasing the levels of its active metabolite N-desmethylclobazam in several studies; this is felt to be due to CBD's inhibition of CYP2C19. EAP data demonstrate other possible interactions with rufinamide, zonisamide, topiramate, and eslicarbazepine. Additionally, there is one case report demonstrating need for warfarin dose adjustment with concomitant CBD. Understanding of CBD's efficacy and safety in the treatment of TRE has expanded significantly in the last few years. Future controlled studies of various ratios of CBD and THC are needed as there could be further therapeutic potential of these compounds for patients with epilepsy.