Clinical and Surgical Factors Associated With Increased Epilepsy Risk in Children With Hydrocephalus

Preparing for Patient-Customized N-of-1 Antisense Oligonucleotide Therapy to Treat Rare Diseases

The process of developing therapies to treat rare diseases is fraught with financial, regulatory, and logistical challenges that have limited our ability to build effective treatments. Recently, a novel type of therapy called antisense therapy has shown immense potential for the treatment of rare diseases, particularly through single-patient N-of-1 trials. Several N-of-1 antisense therapies have been developed recently for rare diseases, including the landmark study of milasen. In response to the success of N-of-1 antisense therapy, the Food and Drug Administration (FDA) has developed unique guidelines specifically for the development of antisense therapy to treat N-of-1 rare diseases. This policy change establishes a strong foundation for future therapy development and addresses some of the major limitations that previously hindered the development of therapies for rare diseases.

Phenotypic overlap between rare disease patients and variant carriers in a large population cohort informs biological mechanisms

The biological mechanisms giving rise to the extreme symptoms exhibited by rare disease patients are complex, heterogenous, and difficult to discern. Understanding these mechanisms is critical for developing treatments that address the underlying causes of diseases rather than merely the presenting symptoms. Moreover, the same dysfunctional biological mechanisms implicated in rare recessive diseases may also lead to milder and potentially preventable symptoms in carriers in the general population. Seizures are a common, extreme phenotype that can result from diverse and often elusive biological pathways in patients with ultrarare or undiagnosed disorders. In this pilot study, we present an approach to understand the biological pathways leading to seizures in patients from the Undiagnosed Diseases Network (UDN) by analyzing aggregated genotype and phenotype data from the UK Biobank (UKB). Specifically, we look for enriched phenotypes across UKB participants who harbor rare variants in the same gene known or suspected to be causally implicated in a UDN patient's recessively manifesting disorder. Analyzing these milder but related associated phenotypes in UKB participants can provide insight into the disease-causing molecular mechanisms at play in the rare disease UDN patient. We present six vignettes of undiagnosed patients experiencing seizures as part of their recessive genetic condition, and we discuss the potential mechanisms underlying the spectrum of symptoms associated with UKB participants to the severe presentations exhibited by UDN patients. We find that in our set of rare disease patients, seizures may result from diverse, multi-step pathways that involve multiple body systems. Analyses of large-scale population cohorts such as the UKB can be a critical tool to further our understanding of rare diseases in general.

Are Patients with Syndromic Craniosynostosis at Greater Risk for Epilepsy than Patients with Nonsyndromic Craniosynostosis?

OBJECTIVE

The aim of this study was to determine whether patients with syndromic craniosynostosis (SCS) are at increased risk for epilepsy relative to patients with nonsyndromic craniosynostosis (NSCS).

METHODS

A retrospective cohort study was completed using the Kids' Inpatient Database (KID). All patients diagnosed with craniosynostosis (CS) were included. The primary predictor variable was study grouping (SCS vs. NSCS). The primary outcome variable was a diagnosis of epilepsy. Descriptive statistics, univariate analyses and multivariate logistic regression were performed to identify independent risk factors for epilepsy.

RESULTS

The final study sample included a total of 10,089 patients (mean age, 1.78 years ± 3.70; 37.7% female). 9278 patients (92.0%) had NSCS, and the remaining 811 patients (8.0%) had SCS. A total of 577 patients (5.7%) had epilepsy. Not controlling for other variables, patients with SCS were at increased risk for epilepsy relative to patients with NSCS (OR 2.1, P < 0.001). After controlling for all significant variables, patients with SCS were no longer at increased risk for epilepsy relative to patients with NSCS (OR 0.73, P = 0.063). Hydrocephalus, Chiari malformation (CM), obstructive sleep apnea (OSA), atrial septal defect (ASD), gastro-esophageal reflux disease (GERD) were all independent risk factors (P < 0.05) for epilepsy.

CONCLUSIONS

Syndromic craniosynostosis (SCS) in itself is not a risk factor for epilepsy relative to NSCS. The greater prevalence of hydrocephalus, CM, OSA, ASD, and GERD, all of which were risk factors for epilepsy, in patients with SCS relative to patients with NSCS likely explains the greater prevalence of epilepsy in SCS relative to NSCS.

Invasive Intracranial Electroencephalogram (EEG) Monitoring for Epilepsy in the Pediatric Patient With a Shunt

The use of invasive intracranial electroencephalogram (EEG) monitoring in the patient with a cerebrospinal fluid (CSF) diversionary shunt presents a conundrum -- the presence of a percutaneous electrode passing into the intracranial compartment presents a pathway for entry of pathogens to which a chronically implanted device like a shunt is especially susceptible to infection. In this case report, we describe the clinical and radiological features, medical and surgical management, and treatment outcomes of pediatric patients with shunted hydrocephalus who underwent invasive intracranial monitoring over an eight-year period. Three cases of children undergoing invasive intracranial monitoring were included in this study. Invasive monitoring for each patient occurred over three to six days. In each case, invasive intracranial monitoring was completed successfully, without resulting infection or shunt malfunction. While the second procedure was complicated by the formation of a pneumocephalus, there was no associated midline shift, and invasive intracranial monitoring was completed without incidence. Each patient received further surgery that successfully reduced seizure frequency. This study suggests that, while children with CSF diversionary shunts are at an inherently increased risk for infection and other complications, invasive intracranial monitoring is a relatively safe and feasible option in these patients. Future studies should explore the optimal duration for intracranial monitoring in pediatric patients with chronically implanted devices.

Is Shunt Location a Risk Factor for the Development of De Novo Post-shunt Seizures?

Background

While ventriculo-extracranial shunting procedures have been the standard treatment option for hydrocephalus for a long time, their long-term morbidity, including the development of post-shunt de Novo seizures, should be taken into account. This study aimed to investigate the rate and risk factors of the occurrence of de Novo post-shunt seizures in patients with hydrocephalus.

Methods

In this retrospective longitudinal study, all patients with hydrocephalus who had ventriculo-peritoneal shunt insertion from 2014 to 2017 at Namazi Hospital, (Shiraz, Iran) were studied. Phone calls were made to all patients to obtain their postoperative seizure outcome and other data (e.g., sex, age at surgery, shunt insertion location, history of seizures before surgery, history of seizures after surgery, any other type of brain surgery, and the etiology of their hydrocephalus). The Pearson Chi Square was used for the analysis of binary variable (e.g., sex) differences, and the t test for the analysis of differences in the means of numerical variables (e.g., age). Bonferroni correction tests were also utilized. P values less than 0.05 were considered significant.

Results

A total of 114 patients were included in the study. Overall, 68 (60%) patients had a frontal location of shunt insertion and 46 (40%) had a parietal site. Twenty-four (21%) patients reported experiencing de Novo post-shunt seizures, 15 of which had a frontal location and nine a parietal location for shunt insertion (P=0.824).

Conclusion

De Novo post-shunt seizures are common occurrences. However, shunt location is not a significant risk factor for the development of de Novo post-shunt seizures.

Postoperative seizures following endoscopic third ventriculostomy and choroid plexus cauterization: a case series

OBJECTIVE

In this study, the authors sought to investigate variables associated with postoperative seizures following endoscopic third ventriculostomy and choroid plexus cauterization (ETV/CPC) for treatment of pediatric hydrocephalus.

METHODS

A retrospective analysis of 37 patients who underwent ETV/CPC for treatment of hydrocephalus at an academic medical center from September 2016 to March 2021 was conducted. Demographics, etiology of hydrocephalus, operative details, electroencephalography (EEG) data, MRI findings, need for subsequent procedures, perioperative laboratory tests, medical history, and presence of clinical postoperative seizures were collected. Postoperative seizures were defined as clinical seizures within 24 hours of surgery. Eighteen patients received levetiracetam intraoperatively as well as over the next 7 days postoperatively for seizure prophylaxis.

RESULTS

Of 37 included patients, 9 (24%) developed clinical seizures within 24 hours after surgery, 5 of whom subsequently had electroclinical seizures captured on video-EEG. The clinical seizures in 4 of those 5 patients (80%) may have been associated with the hemisphere of the brain through which the endoscope was introduced. The median corrected age of the cohort was 3.4 months. The median corrected age of patients who did not develop postoperative seizures was 2.3 months compared with 0.7 months for patients who did develop postoperative seizures (p > 0.99). Postoperative seizures occurred in 43% (3/7) of prenatally repaired myelomeningocele patients versus 29% (2/7) of postnatally repaired myelomeningocele patients. Of the 18 patients who received prophylactic levetiracetam, none (0%) developed postoperative seizures compared with 9 of the 19 patients (47%) who did not receive prophylactic levetiracetam (p = 0.014).

CONCLUSIONS

Postoperative seizures were recorded in 24% of the pediatric patients who underwent ETV/CPC for hydrocephalus, which is higher than previously reported rates in the literature of 5%. Since 80% of the postoperative electrographic seizures may have been associated with the hemisphere through which the endoscope was introduced, the surgical entry site may contribute to postoperative seizure development. In patients who received prophylactic perioperative levetiracetam, the postoperative seizure incidence dropped to 0% compared with 47% in those who did not receive prophylactic perioperative levetiracetam. This finding indicates that the use of prophylactic perioperative levetiracetam may be efficacious in the prevention of clinical seizures in this patient population.

Post-operative seizure after first time endoscopic third ventriculostomy in pediatric patients

PURPOSE

Post-operative seizure rates after endoscopic third ventriculostomy (ETV) are not definitively known. We analyzed our institution's experience for all causes of hydrocephalus in pediatric patients undergoing ETV to determine rates of post-ETV seizure.

METHODS

A retrospective review of institutional pediatric patients undergoing ETV from May 2014 to December 2018. Included were < 21 years, with 1-year follow-up. Exclusion criteria included ventriculoperitoneal shunts (VPS) prior to ETV, VPS within 7 days post-ETV, and prior seizure disorder. Data included age, gender, diagnosis, early post-operative seizure (within 7 days post-ETV), late post-operative seizures (after first 7 days and within first year post-ETV), concomitant choroid plexus cauterization (CPC), VPS conversion within 1 year, and administration of prophylactic antiepileptics.

RESULTS

Sixty of 81 ETV cases were included; 41% underwent concomitant CPC. Of these, 53% (n = 32) were male, 46% (n = 28) female, averaging 5.8 years, with the most common diagnosis neoplasm-related obstructive hydrocephalus (38.3%, n = 23). Early post-operative seizure occurred in 6.7% (n = 4); late post-operative seizure occurred in 8.3% (n = 5). Late post-operative seizures were higher in patients experiencing early post-operative seizure versus those without (75% vs 3.7%, p = 0.003). Late post-operative seizure occurred in 13.6% (n = 3 patients) requiring VPS versus 5.3% (n = 2 patients) with successful ETV (p = 0.36). Rates did not correlate with pathology. No patients received prophylactic antiepileptics prior to surgery or exhibiting a seizure.

CONCLUSIONS

Patients with early post-operative seizures have an increased likelihood of developing late post-operative seizures. Pediatric ETV patients may have a lower rate of both early and late post-operative seizure; underlying pathology may influence these rates.

Post-haemorrhagic hydrocephalus is associated with poorer surgical and neurodevelopmental sequelae than other causes of infant hydrocephalus

PURPOSE

This retrospective cohort study aimed to investigate the surgical and neurodevelopmental outcomes (NDO) of infant hydrocephalus. We also sought to determine whether these outcomes are disproportionately poorer in post-haemorrhagic hydrocephalus (PHH) compared to other causes of infant hydrocephalus.

METHODS

A review of all infants with hydrocephalus who had ventriculoperitoneal (VP) shunts inserted at Great Ormond Street Hospital (GOSH) from 2008 to 2018 was performed. Demographic, surgical, neurodevelopmental, and other clinical data extracted from electronic patient notes were analysed by aetiology. Shunt survival, NDO, cerebral palsy (CP), epilepsy, speech delay, education, behavioural disorders, endocrine dysfunction, and mortality were evaluated.

RESULTS

A total of 323 infants with median gestational age of 37.0 (23.29-42.14) weeks and birthweight of 2640 g (525-4684 g) were evaluated. PHH was the most common aetiology (31.9%) and was associated with significantly higher 5-year shunt revision rates, revisions beyond a year, and median number of revisions than congenital or "other" hydrocephalus (all p < 0.02). Cox regression demonstrated poorest shunt survival in PHH, related to gestational age at birth and corrected age at shunt insertion. PHH also had the highest rate of severe disabilities, increasing with age to 65.0% at 10 years, as well as the highest CP rate; only genetic hydrocephalus had significantly higher endocrine dysfunction (p = 0.01) and mortality rates (p = 0.04).

CONCLUSIONS

Infants with PHH have poorer surgical and NDO compared to all other aetiologies, except genetic hydrocephalus. Research into measures of reducing neurodisability following PHH is urgently required. Long-term follow-up is essential to optimise support and outcomes.

The Incidence of Postoperative Seizures Following Treatment of Postinfectious Hydrocephalus in Ugandan Infants: A Post Hoc Comparison of Endoscopic Treatment vs Shunt Placement in a Randomized Controlled Trial

BACKGROUND

There are currently no published data directly comparing postoperative seizure incidence following endoscopic third ventriculostomy (ETV), with/without choroid plexus cauterization (CPC), to that for ventriculoperitoneal shunt (VPS) placement.

OBJECTIVE

To compare postoperative epilepsy incidence for ETV/CPC and VPS in Ugandan infants treated for postinfectious hydrocephalus (PIH).

METHODS

We performed an exploratory post hoc analysis of a randomized trial comparing VPS and ETV/CPC in 100 infants (<6 mo old) presenting with PIH. Minimum follow-up was 2 yr. Variables associated with and the incidence of postoperative epilepsy were compared (intention-to-treat) using a bivariate analysis. Time to first seizure was compared using the Kaplan-Meier method, and the relative risk for the 2 treatments was determined using Mantel-Haenszel hazard ratios.

RESULTS

Seizure incidence was not related to age (P = .075), weight (P = .768), sex (P = .151), head circumference (P = .281), time from illness to hydrocephalus onset (P = .973), or hydrocephalus onset to treatment (P = .074). Irritability (P = .027) and vision deficit (P = .04) were preoperative symptoms associated with postoperative seizures. Ten (10%) patients died, and 20 (20%) developed seizures over the follow-up period. Overall seizure incidence was 9.4 per 100 person-years (9.4 and 9.5 for ETV/CPC and VPS, respectively; P = .483), with no significant difference in seizure risk between groups (hazard ratio, 1.02; 95% CI: 0.42, 2.45; P = .966). Mean time to seizure onset was 8.5 mo for ETV/CPC and 11.2 mo for VPS (P = .464). As-treated, per-protocol, and attributable-intervention analyses yielded similar results.

CONCLUSION

Postoperative seizure incidence following treatment of PIH was 20% within 2 yr, regardless of treatment modality.

Epileptic Spasms Predict Poor Epilepsy Outcomes After Perinatal Stroke

Perinatal stroke is a significant cause of severe epilepsy, including epileptic spasms. Although epileptic spasms due to underlying structural lesion often respond poorly to treatment and evolve into drug-resistant epilepsy, outcomes are not uniformly poor, and predictors of outcomes are not well described. We performed a single-institution retrospective review of epileptic spasms following perinatal stroke to determine if outcome depended on vascular subtype. We identified 24 children with epileptic spasms due to perinatal ischemic stroke: 11 cases of perinatal arterial stroke and 13 cases of perinatal venous infarct. Initial response to treatment was similar between groups; however, although children with perinatal arterial stroke who responded to epileptic spasms therapy had high rates of seizure freedom, many children with perinatal venous infarct, regardless of initial response, had residual drug-resistant epilepsy. We consider whether the mechanism for epileptogenesis may be different between arterial and venous strokes, and whether these 2 groups should be monitored for epileptic spasms, and subsequent epilepsy, differently.

Surprisingly good outcome in antenatal diagnosis of severe hydrocephalus related to CCDC88C deficiency

Non-syndromic congenital hydrocephalus is aetiologically diverse and while a genetic cause is frequently suspected, it often cannot be confirmed. The most common genetic cause is L1CAM-related X-linked hydrocephalus and that explains only 5%-10% of all male cases. This underlines a current limitation in our understanding of the genetic burden of non-syndromic congenital hydrocephalus, especially for those cases with likely autosomal recessive inheritance. Additionally, the prognosis for most cases of severe congenital hydrocephalus is poor, with most of the surviving infants displaying significant intellectual impairment despite surgical intervention. It is for this reason that couples with an antenatal diagnosis of severe hydrocephalus are given the option, and may opt, for termination of the pregnancy. We present two families with CCDC88C-related recessive congenital hydrocephalus with children who had severe hydrocephalus. Those individuals who were shunted within the first few weeks of life, who did not require multiple surgical revisions, and who had a more distal truncating variant of the CCDC88C gene met their early childhood developmental milestones in some cases. This suggests that children with CCDC88C-related autosomal recessive hydrocephalus can have normal developmental outcomes under certain circumstances. We recommend CCDC88C analysis in cases of severe non-syndromic congenital hydrocephalus, especially when aqueduct stenosis with or without a medial diverticulum is seen, in order to aid prognosis discussion.