Amelioration of intractable epilepsy by adjunct vagus nerve stimulation therapy in a girl with a CDKL5 mutation

Surgical outcomes of patients with genetically refractory epilepsy: A systematic review and meta-analysis

OBJECTIVE

To summarize the surgical outcomes of genetically refractory epilepsy and identify prognostic factors for these outcomes.

METHODS

A literature search of the PubMed, Web of Science, and Embase databases for relevant studies, published between January 1, 2002 and December 31, 2023, was performed using specific search terms. All studies addressing surgical outcomes and follow-up of genetically refractory epilepsy were included. All statistical analyses were performed using STATA software (StataCorp LLC, College Station, TX, USA). This review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, 2020 (i.e., "PRISMA") reporting guidelines.

RESULTS

Of the 3833 studies retrieved, 55 fulfilled the inclusion criteria. Eight studies were eligible for meta-analysis at the study level. Pooled outcomes revealed that 74 % of patients who underwent resective surgery (95 % confidence interval [CI] 0.55-0.89; z = 9.47, p < 0.05) achieved Engel I status at the last follow-up. In the study level analysis, pooled outcomes revealed that 9 % of patients who underwent vagus nerve stimulation achieved seizure-free status (95 % CI 0.00-0.31; z = 1.74, p < 0.05), and 61 % (95 % CI 0.55-0.89; z = 11.96, p < 0.05) achieved a 50 % reduction in seizure frequency at the last follow-up. Fifty-three studies comprising 249 patients were included in an individual-level analysis. Among patients who underwent lesion resection or lobectomy/multilobar resection, 65 % (100/153) achieved Engel I status at the last follow-up. Univariate analysis indicated that female sex, somatic mutations, and presenting with focal seizure symptoms were associated with better prognosis (p < 0.05). Additionally, 75 % (21/28) of patients who underwent hemispherectomy/hemispherotomy achieved Engel I status at the last follow-up. In the individual-level analysis, among patients treated with vagus nerve stimulation, 21 % (10/47) were seizure-free and 64 % (30/47) experienced >50 % reduction in seizure frequency compared with baseline.

CONCLUSION

Meticulous presurgical evaluation and selection of appropriate surgical procedures can, to a certain extent, effectively control seizures. Therefore, various surgical procedures should be considered when treating patients with genetically refractory epilepsy.

Current Overview of CDKL-5 Deficiency Disorder Treatment

CDKL5 deficiency disorder (CDD) is a complex of clinical symptoms resulting from the presence of non-functional or absent CDKL5 protein, a serine-threonine kinase involved in neural maturation and synaptogenesis [...].

CDKL5-associated developmental and epileptic encephalopathy: A long-term, longitudinal electroclinical study of 22 cases

OBJECTIVE

The study was conducted to analyze the possible diagnostic value of the electroclinical semiology of the epileptic seizures.

METHODS

We evaluated the medical records of 17 females and 5 males with CDKL5 deficiency disorder (CDD) considering the long-term evolution, including the polygraphic video-EEG recordings.

RESULTS

We recognized three disease phases. We found that the seizure semiology was already recognizable in the first phase of the syndrome. In the short-term evolution, all patients had focal motor and 12/21 hypermotor seizures. Both epileptic spasms and myoclonic seizures were already present in more than half of the cases in the first 2 months after onset. In the second phase, the intermediate period, the polymorphic pattern was maintained, but in eight patients the electroclinical pattern of epileptic encephalopathy with hypsarrhythmia appeared. In the long-term period, the seizure polymorphism continued but myoclonic and epileptic spasms diminished. Tonic seizures appeared in the last 2 phases. Progressively, with the aggravation of seizures and paroxysmal EEG abnormalities impairment of the neurocognitive status was observed. Severe behavioral disturbances were seen in eight and autistic-like features in 14.

CONCLUSION

CDD is a true developmental and epileptic encephalopathy with a specific etiology characterized by the early appearance of epileptic seizures that quickly become polymorphic and drug resistant in infants that are most often female and already have neurological impairment. Polygraphic video-EEG recordings are important to recognize ictal events of the association of hypermotor seizures, epileptic spasms in clusters, and massive myoclonic jerks, already present at onset.

Vagus nerve stimulation in children with drug-resistant epilepsy of monogenic etiology

Vagus nerve stimulation (VNS) is an effective treatment for drug-resistant epilepsy (DRE). The present study evaluated the efficacy of VNS in pediatric patients with DRE of monogenic etiology. A total of 20 patients who received VNS treatment at our center were followed up every 3 months through outpatient visits or a remote programming platform. The median follow-up time was 1.4 years (range: 1.0–2.9). The rate of response to VNS at 12 months of follow-up was 55.0% (11/20) and the seizure-free rate was 10.0% (2/20). We found that 75.0% (3/4) of patients with an SCN1A variant had a >50% reduction in seizure frequency. Patients with pathogenic mutations in the SLC35A2, CIC, DNM1, MBD5, TUBGCP6, EEF1A2, and CHD2 genes or duplication of X q28 (MECP2 gene) had a >50% reduction in seizure frequency. Compared with the preoperative electroencephalography (EEG), at 6, 12, 18, and 24 months after stimulator implantation, the percentage of the patients whose background frequency increased >1.5 Hz was respectively, 15.0% (3/20), 50.0% (10/20), 58.3% (7/12) and 62.5% (5/8); the percentage of the patients whose interictal EEG showed a >50% decrease in spike number was respectively 10% (2/20), 40.0% (8/20), 41.6% (5/12) and 50.0% (4/8). In the 9 patients with no response to VNS treatment, there was no difference in terms of spike number and background frequency between preoperative and postoperative EEG. Five of the 20 children (25.0%) reached new developmental milestones or acquired new skills after VNS compared to the preoperative evaluation. The efficacy of VNS in pediatric patients with DRE of monogenic etiology is consistent with that in the overall population of pediatric DRE patients. Patients with Dravet syndrome (DS), tuberous sclerosis complex (TSC), or Rett syndrome/MECP2 duplication syndrome may have a satisfactory response to VNS, but it is unclear whether patients with rare variants of epilepsy-related genes can benefit from the treatment.

CDKL5 Deficiency Disorder-Related Epilepsy: A Review of Current and Emerging Treatment

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a developmental and epileptic encephalopathy with infantile-onset epilepsy. Most individuals with CDD develop refractory epilepsy with multiple seizure types. Management of seizures in CDD remains challenging for clinicians given the highly refractory nature of seizures and the limited number of disease-specific studies that offer a high level of evidence. Epileptic spasms are the most common seizure type in CDD and are more often refractory to standard first-line treatment than are spasms of other etiologies. In other seizure types, the effectiveness of antiseizure medications is limited and wanes over time. Ketogenic diet and palliative surgical treatments have both had mixed results in observational studies. When treating refractory seizures in CDD, we recommend carefully balancing seizure control and treatment-related side effects to optimize each individual's overall quality of life. Clinical trials of medications targeting epilepsy in CDD have been conducted, and additional investigational small molecules, gene therapy, and other disease-modifying therapies are in development for CDD.

The role of vagus nerve stimulation in genetic etiologies of drug-resistant epilepsy: a meta-analysis

OBJECTIVE

Drug-resistant epilepsy (DRE) affects many children. Vagus nerve stimulation (VNS) may improve seizure control; however, its role in children with genetic etiologies of epilepsy is not well described. The authors systematically reviewed the literature to examine the effectiveness of VNS in this cohort.

METHODS

In January 2021, the authors performed a systematic review of the PubMed/MEDLINE, SCOPUS/Embase, Cochrane, and Web of Science databases to investigate the impact of VNS on seizure outcomes in children with genetic etiologies of epilepsy. Primary outcomes included seizure freedom rate, ≥ 90% seizure reduction rate, and ≥ 50% seizure reduction rate. Secondary outcomes were seizure severity and quality of life (QOL), including cognitive, functional, and behavioral outcomes. A random-effects meta-analysis was performed.

RESULTS

The authors identified 125 articles, of which 47 with 216 nonduplicate patients were analyzed. Common diagnoses were Dravet syndrome (DS) (92/216 patients [42.6%]) and tuberous sclerosis complex (TSC) (63/216 [29.2%]). Seizure freedom was not reported in any patient with DS; the pooled proportion (95% CI) of patients with ≥ 50% seizure reduction was 41% (21%-58%). Secondary cognitive outcomes of VNS were variable in DS patients, but these patients demonstrated benefits in seizure duration and status epilepticus. In TSC patients, the pooled (95% CI) seizure freedom rate was 40% (12%-71%), ≥ 90% seizure reduction rate was 31% (8%-56%), and ≥ 50% reduction rate was 68% (48%-91%). Regarding the secondary outcomes of VNS in TSC patients, several studies reported decreased seizure severity and improved QOL outcomes. There was limited evidence regarding the use of VNS to treat patients with other genetic etiologies of epilepsy, such as mitochondrial disease, Rett syndrome, Doose syndrome, Landau-Kleffner syndrome, Aicardi syndrome, Angelman syndrome, ring chromosome 20 syndrome, and lissencephaly; variable responses were reported in a limited number of cases.

CONCLUSIONS

The authors conducted a systematic review of VNS outcomes in children with genetic etiologies of DRE. Among the most studied conditions, patients with TSC had substantial seizure reduction and improvements in QOL, whereas those with DS had less robust seizure reduction. Increased testing, diagnosis, and long-term follow-up studies are necessary to better characterize VNS response in these children.

Refractory Status Epilepticus in Genetic Epilepsy-Is Vagus Nerve Stimulation an Option?

Refractory and super-refractory status epilepticus (RSE, SRSE) are severe conditions that can have long-term neurological consequences with high morbidity and mortality rates. The usefulness of vagus nerve-stimulation (VNS) implantation during RSE has been documented by anecdotal cases and in systematic reviews; however, the use of VNS in RSE has not been widely adopted. We successfully implanted VNS in two patients with genetic epilepsy admitted to hospital for SRSE; detailed descriptions of the clinical findings and VNS parameters are provided. Our patients were implanted 25 and 58 days after status epilepticus (SE) onset, and a stable remission of SE was observed from the seventh and tenth day after VNS implantation, respectively, without change in anti-seizure medication. We used a fast ramp-up of stimulation without evident side effects. Our results support the consideration of VNS implantation as a safe and effective adjunctive treatment for SRSE.

Novel CDKL5 mutations were found in patients in China: retrospective investigation in cases of CDKL5-related disorders

Objective

CDKL5-related disorders (CDD) is an epileptic encephalopathy resulted of gene mutations of CDKL5. This study aimed to explore the development process of CDD and to expand its mutation spectrum.

Methods

Clinic datawas collected about three infantile epileptic encephalopathy cases diagnosed at Xinhua Hospital Affiliated to Shanghai Jiaotong University, School of Medicine. Next generation sequencing technology was used to find three de novo mutations of CDKL5. We searched published literatures about CDKL5 in pubmed and made an analysis about our clinic data and the related literatures.

Results

The three patients were all girls. Their average onset age of seizures was around 2 months, and all of them have intractable epileptic seizures, severe intellectual disability, and hypotension. Among them, two presented infantile spasm and high arrhythmia in EEG, and the other manifested clonic seizure and broad epileptiform discharge in EEG. Extracerebral space widening in cranial MRIs was demonstrated in two cases. Visual evoked potential was abnormal in two cases. Seizures were resistant to all kinds of antiepileptic drugs (AEDs). Gene tests showed three de novo mutations of CDKL5: one was a truncated mutation (c.2254A > T,P.R752X, stop279), which was pathogenic according to the ACMG guide, the other two were missense mutations (c.377G > T,p.Cys126Phe) and a frameshift mutation (c.362-362insG(p.Ala122GlyfsTer7), which were likely pathogenic according to the ACMG.

Conclusions

All three de novo mutations are first reported. Based on the combined related literature and the manifestations observed, we diagnosed the three children as CDKL5-related disorders, and concluded that the de novo CDKL5 mutations are the reason for their epilepsy.

CDKL5 Deficiency Disorder-A Complex Epileptic Encephalopathy

CDKL5 deficiency disorder (CDD) is a complex of clinical symptoms resulting from the presence of non-functional CDKL5 protein, i.e., serine-threonine kinase (previously referred to as STK9), or its complete absence. The clinical picture is characterized by epileptic seizures (that start within the first three months of life and most often do not respond to pharmacological treatment), epileptic encephalopathy secondary to seizures, and retardation of psychomotor development, which are often observed already in the first months of life. Due to the fact that CDKL5 is located on the X chromosome, the prevalence of CDD among women is four times higher than in men. However, the course is usually more severe among male patients. Recently, many clinical centers have analyzed this condition and provided knowledge on the function of CDKL5 protein, the natural history of the disease, therapeutic options, and their effectiveness and prognosis. The International CDKL5 Disorder Database was established in 2012, which focuses its activity on expanding knowledge related to this condition and disseminating such knowledge to the families of patients.

Vagus nerve stimulation for pediatric patients with drug-resistant epilepsy caused by genetic mutations: Two cases

Vagus nerve stimulation (VNS) is a neuromodulation therapy increasingly used for treating drug-resistant epilepsy. However, it remains to be determined which patients are best suited for the treatment, and it is difficult to predict the therapeutic effect before the implantation. Mutations in some genes could lead to epilepsy. Here we report two cases of pediatric patients with drug-resistant epilepsy treated by VNS therapy: Patient 1 with ARX mutation achieved good outcomes; Patient 2 with the CDKL5 mutation did not show improvement. Additionally, the therapeutic impact of VNS on brain networks was investigated, hoping to provide some empirical evidence for a better understanding of the mechanism of VNS treatment.

Cyclin-Dependent Kinase-Like 5 Deficiency Disorder: Clinical Review

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a developmental encephalopathy caused by pathogenic variants in the gene CDKL5. This unique disorder includes early infantile onset refractory epilepsy, hypotonia, developmental intellectual and motor disabilities, and cortical visual impairment. We review the clinical presentations and genetic variations in CDD based on a systematic literature review and experience in the CDKL5 Centers of Excellence. We propose minimum diagnostic criteria. Pathogenic variants include deletions, truncations, splice variants, and missense variants. Pathogenic missense variants occur exclusively within the kinase domain or affect splice sites. The CDKL5 protein is widely expressed in the brain, predominantly in neurons, with roles in cell proliferation, neuronal migration, axonal outgrowth, dendritic morphogenesis, and synapse development. The molecular biology of CDD is revealing opportunities in precision therapy, with phase 2 and 3 clinical trials underway or planned to assess disease specific and disease modifying treatments.

Clinical and genetic spectrum of a large cohort of children with epilepsy in China

PURPOSE

Genetic diagnosis for children suffering from epilepsy has important implications for treatment, prognosis, and development of precision medicine strategies.

METHODS

We performed exome sequencing (ES) or targeted sequencing on 733 children with epilepsy onset within the first year of life. We subgrouped our patients based on the onset age of seizure into neonatal and before 1 year (1-12 months), to compare the clinical and genetic features.

RESULTS

The subgroups with different onset age of seizure showed different pathogenic variant spectrum, and the 1-year age group was more likely to have developmental delays than the neonate group (p = 0.000614). The diagnostic rate was 26.7% for targeted sequencing using a 2742-gene panel, and 42% for ES. We identified 12 genes, which covered 48.7% of diagnostic cases. Our data revealed that 41.9% of patients in the neonate group and 49.7% patients in the 1-year group had treatment options based on molecular diagnosis.

CONCLUSION

The 12 most commonly implicated genes in this cohort and the genes with treatment options should be considered as part of the essential panel for early diagnosis of epilepsy onset, if large medical exome analyses or ES are not feasible as first-tier analysis. Genetic results are beginning to improve therapy by antiepileptic medication selections and precision medicine approaches.

Mice lacking cyclin-dependent kinase-like 5 manifest autistic and ADHD-like behaviors

Neurodevelopmental disorders frequently share common clinical features and appear high rate of comorbidity, such as those present in patients with attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). While characterizing behavioral phenotypes in the mouse model of cyclin-dependent kinase-like 5 (CDKL5) disorder, a neurodevelopmental disorder caused by mutations in the X-linked gene encoding CDKL5, we found that these mice manifested behavioral phenotypes mimicking multiple key features of ASD, such as impaired social interaction and communication, as well as increased stereotypic digging behaviors. These mice also displayed hyper-locomotion, increased aggressiveness and impulsivity, plus deficits in motor and associative learning, resembling primary symptoms of ADHD. Through brain region-specific biochemical analysis, we uncovered that loss of CDKL5 disrupts dopamine synthesis and the expression of social communication-related key genes, such as forkhead-box P2 and mu-opioid receptor, in the corticostriatal circuit. Together, our findings support that CDKL5 plays a role in the comorbid features of autism and ADHD, and mice lacking CDKL5 may serve as an animal model to study the molecular and circuit mechanisms underlying autism-ADHD comorbidity.