Definitive treatment of seizures due to hemimegalencephaly in neonates and young infants by transarterial embolization: technical considerations for 'endovascular embolic hemispherectomy'

BACKGROUND

This case series describes the technical considerations and effectiveness of 'endovascular embolic hemispherectomy' for the treatment of medically intractable seizures in neonates and young infants with hemimegalencephaly (HME) and in whom surgical hemispherectomy is not a viable option.

METHODS

This is a descriptive review of the endovascular technique used to treat consecutive pediatric patients with serial transarterial embolization for intractable seizures due to HME between 2018 and 2022. Clinical presentation, endovascular procedural details and complications, and efficacy were examined.

RESULTS

Three infants (13-day-old, 13-week-old and 15-day-old) with HME and intractable seizures underwent a total of 10 transarterial embolizations. Anticipated intraprocedural events included vasospasm and focal subarachnoid hemorrhage in all three infants, effectively controlled endovascularly, and non-target embolization in one infant. No infants had symptomatic intracranial hemorrhage or femoral artery occlusion. EEG background quiescence and seizure cessation was achieved after the final stage of embolization in all patients. All infants were discharged home from the neonatal ICU (median length of stay 36 days, range 27-74 days) and remain seizure-free to date (4 years, 9 months, and 8 months). None have developed hydrocephalus, required surgical hemispherectomy or other neurosurgical interventions.

CONCLUSION

Endovascular hemispherectomy can be safely used to provide definitive treatment of HME-related epilepsy in neonates and young infants when intraprocedural events are managed effectively. This less invasive novel approach should be considered a feasible early alternative to surgical hemispherectomy. Further studies are needed to enhance the safety profile and to assess long-term neurodevelopmental outcome and durability of freedom from seizures.

Pearls & Oy-sters: Delayed Response to Pyridoxine in Pyridoxine-Dependent Epilepsy

Inborn errors of metabolism are a diverse group of genetic disorders including many that cause neonatal-onset epilepsy such as pyridoxine-dependent epilepsy (PDE). PDE occurs secondary to biallelic pathogenic variants in ALDH7A1 and can present with refractory neonatal seizures and status epilepticus. Neonatal seizures and encephalopathy are modifiable with pyridoxine (vitamin B6) supplementation. However, the clinical response to pyridoxine supplementation can be delayed. We present the case of a full-term neonate with PDE in which seizure cessation was seen a few hours after intravenous pyridoxine load, but the improvement in EEG background and level of clinical encephalopathy occurred 5 days later. We share this case to provide an example in which clinical improvement in PDE was gradual and required continuation of treatment for several days illustrating the necessity of continuing vitamin B6 supplementation in suspected cases until confirmatory genetic testing is obtained or an alternate cause is found.

Neurotoxic properties of the Zika virus envelope protein

Prenatal Zika virus (ZIKV) infection is a serious global concern as it can lead to brain injury and many serious birth defects, collectively known as congenital Zika syndrome. Brain injury likely results from viral mediated toxicity in neural progenitor cells. Additionally, postnatal ZIKV infections have been linked to neurological complications, yet the mechanisms driving these manifestations are not well understood. Existing data suggest that the ZIKV envelope protein can persist in the central nervous system for extended periods of time, but it is unknown if this protein can independently contribute to neuronal toxicity. Here we find that the ZIKV envelope protein is neurotoxic, leading to overexpression of poly adenosine diphosphate -ribose polymerase 1, which can induce parthanatos. Together, these data suggest that neuronal toxicity resulting from the envelope protein may contribute to the pathogenesis of post-natal ZIKV-related neurologic complications.

Validation of a computational phenotype for finding patients eligible for genetic testing for pathogenic PTEN variants across three centers

BACKGROUND

Computational phenotypes are most often combinations of patient billing codes that are highly predictive of disease using electronic health records (EHR). In the case of rare diseases that can only be diagnosed by genetic testing, computational phenotypes identify patient cohorts for genetic testing and possible diagnosis. This article details the validation of a computational phenotype for PTEN hamartoma tumor syndrome (PHTS) against the EHR of patients at three collaborating clinical research centers: Boston Children's Hospital, Children's National Hospital, and the University of Washington.

METHODS

A combination of billing codes from the International Classification of Diseases versions 9 and 10 (ICD-9 and ICD-10) for diagnostic criteria postulated by a research team at Cleveland Clinic was used to identify patient cohorts for genetic testing from the clinical data warehouses at the three research centers. Subsequently, the EHR-including billing codes, clinical notes, and genetic reports-of these patients were reviewed by clinical experts to identify patients with PHTS.

RESULTS

The PTEN genetic testing yield of the computational phenotype, the number of patients who needed to be genetically tested for incidence of pathogenic PTEN gene variants, ranged from 82 to 94% at the three centers.

CONCLUSIONS

Computational phenotypes have the potential to enable the timely and accurate diagnosis of rare genetic diseases such as PHTS by identifying patient cohorts for genetic sequencing and testing.

1872. Neurodevelopment in Apparently Normal Infants from Zika Virus Positive Pregnancies

Background

Congenital Zika syndrome (CZS) is seen in 5–12% of newborns from Zika virus (ZIKV)-infected pregnancies and includes severe neurologic abnormalities. However, the majority of ZIKV-exposed newborns do not have CZS. The risk for neurodevelopmental impairment for infants without CZS following in utero ZIKV is not well known. The objective was to determine whether infants without CZS exposed to ZIKV in utero, have normal neurodevelopment.

Methods

We performed a longitudinal study of neurodevelopment in Colombia for infants exposed to ZIKV in utero who had a normal fetal brain MRI (Mulkey et al, JAMA Peds 2019) and normal head circumference at birth. Infant development was assessed by the Warner Initial Developmental Evaluation of Adaptive and Functional Skills (WIDEA) and the Alberta Infant Motor Scale (AIMS) between 6 and 18 months of age. In-person training was done by a neurologist. The AIMS were video-recorded and scored centrally. Interrater reliability for the novel method of video-based AIMS was determined. WIDEA and AIMS scores were converted to Z-scores compared with normative samples. We also compared development between infants with normal and nonspecific findings on cranial ultrasound (US).

Results

Seventy-two non-CZS infants had neurodevelopmental tests; 40 were at a mean (SD) of 5.7 (0.9) months and 66 were at 13.5 (3.2) months of age. Thirty-four had two assessments. The total WIDEA, social cognition, and mobility domain scores became more abnormal with postnatal age (figure). The AIMS scores were similar to the normative sample. Three infants had an AIMS score < 2 SD’s below the norm. On cranial US, 19 infants (26%) had a nonspecific finding (lenticulostriate vasculopathy, choroid plexus cysts, subependymal cysts, and/or calcification). Infants with a US finding had a lower WIDEA mobility score than infants with normal US (P = .054). There was a trend toward lower AIMS scores in infants with US findings compared with infants with normal US (P = .26). AIMS Interrater agreement on video-based scoring was good (ICC = 0.73, 95% CI 0.42, 0.87).

Conclusion

ZIKV-exposed infants without CZS are at risk for neurodevelopmental delay. Nonspecific cranial US findings may represent mild ZIKV-related injury. Long-term neurodevelopmental follow-up is important for all ZIKV-exposed infants.

Disclosures

All Authors: No reported Disclosures.

Neuroimaging Findings in Normocephalic Newborns With Intrauterine Zika Virus Exposure

BACKGROUND

Congenital Zika infection can result in a spectrum of neurological abnormalities in the newborn. Newborns exposed to Zika virus in utero often have neuroimaging as part of their clinical evaluation.

METHODS

Through the Congenital Zika Program at Children's National Health System in Washington DC, we performed fetal or neonatal neuroimaging, including magnetic resonance imaging and ultrasound, on over 70 fetuses or neonates with intrauterine Zika exposure. Novel findings on neonatal brain magnetic resonance imaging were observed in two instances.

RESULTS

Gadolinium-contrast magnetic resonance imaging showed enhancement of multiple cranial nerves at three days of age on one infant. Another infant underwent magnetic resonance imaging at 16 days of age and was shown to have a chronic ischemic cerebral infarction. This infant had previously normal fetal magnetic resonance imaging.

CONCLUSION

Cranial nerve enhancement and cerebral infarction may be among the expanding list of neurological findings in congenital Zika infection. Postnatal brain magnetic resonance imaging should be considered for newborns exposed to Zika virus in utero.

Fetal and Postnatal Brain Imaging for the Detection of ZIKV Encephalopathy in the Fetus/Newborn

Background

Up to 15% of pregnancies complicated by maternal ZIKV infection result in Zika-virus associated brain abnormalities in the fetus/newborn. Fetal ultrasound (feUS) is the standard imaging modality for the evaluation of fetal anatomy and for brain changes from congenital infection. Fetal MRI (feMRI) may be a useful adjunct.

Methods

We performed a prospective longitudinal neuroimaging study of fetuses/newborns of pregnant women with clinical and/or lab confirmed (RT-PCR and/or IgM/PRNT) diagnosis of Zika infection in Barranquilla, Colombia (endemic) and in Washington, DC, USA (travel-related). Gestational age (GA) at exposure and timing between ZIKV exposure/symptoms and imaging was documented. Subjects had one to two feMRIs and feUS, depending upon GA at enrollment. The feMRI and feUS protocols were standardized between sites and studies were centrally interpreted at Children’s National. Postnatally, infants received an unsedated brain MRI and head US.

Results

Forty-eight, ZIKV exposed/infected in first or second trimester pregnant women were enrolled (46 Colombia, 2 USA). Subjects had symptoms of ZIKV infection at mean of 8.4±5.7 week GA. The first feMRI and feUS were performed at 25.1±6.3 week GA. Thirty-six infants had a second feMRI and feUS at 31.1±4.2 week GA. Three of 48 (6%) cases had an abnormal feMRI: (1) heterotopias and abnormal cortical indent; (2) parietal encephalocele and Chiari II; (3) thin corpus callosum, dysplastic brainstem, temporal cysts, subependymal heterotopias, and generalized cerebral/cerebellar atrophy. FeUS in these three cases found (1) normal study; (2) parietal encephalocele and Chiari II; (3) significant ventriculomegaly with decreasing percentiles of head circumference from 32 to 36 week GA (38% to 3.6%). Postnatal head US revealed findings not seen on feUS: choroid plexus or germinal matrix cysts in nine infants and lenticulostriate vasculopathy in one infant.

Conclusion

FeMRI and feUS provide complimentary information in the assessment of fetal brain changes in ZIKV. In cases of abnormal brain structure, feMRI reveals more extensive areas of brain damage than is seen by US. Further studies are needed to determine whether cystic changes on postnatal head US are related to ZIKV infection, or are incidental findings.

Disclosures

All authors: No reported disclosures.

Vaccine platforms combining circumsporozoite protein and potent immune modulators, rEA or EAT-2, paradoxically result in opposing immune responses

Background

Malaria greatly impacts the health and wellbeing of over half of the world's population. Promising malaria vaccine candidates have attempted to induce adaptive immune responses to Circumsporozoite (CS) protein. Despite the inclusion of potent adjuvants, these vaccines have limited protective efficacy. Conventional recombinant adenovirus (rAd) based vaccines expressing CS protein can induce CS protein specific immune responses, but these are essentially equivalent to those generated after use of the CS protein subunit based vaccines. In this study we combined the use of rAds expressing CS protein along with rAds expressing novel innate immune response modulating proteins in an attempt to significantly improve the induction of CS protein specific cell mediated immune (CMI) responses.

Methods and Findings

BALB/cJ mice were co-vaccinated with a rAd vectors expressing CS protein simultaneous with a rAd expressing either TLR agonist (rEA) or SLAM receptors adaptor protein (EAT-2). Paradoxically, expression of the TLR agonist uncovered a potent immunosuppressive activity inherent to the combined expression of the CS protein and rEA. Fortunately, use of the rAd vaccine expressing EAT-2 circumvented CS protein's suppressive activity, and generated a fivefold increase in the number of CS protein responsive, IFNγ secreting splenocytes, as well as increased the breadth of T cells responsive to peptides present in the CS protein. These improvements were positively correlated with the induction of a fourfold improvement in CS protein specific CTL functional activity in vivo.

Conclusion

Our results emphasize the need for caution when incorporating CS protein into malaria vaccine platforms expressing or containing other immunostimulatory compounds, as the immunological outcomes may be unanticipated and/or counter-productive. However, expressing the SLAM receptors derived signaling adaptor EAT-2 at the same time of vaccination with CS protein can overcome these concerns, as well as significantly improve the induction of malaria antigen specific adaptive immune responses in vivo.

Wild-type adenoviruses from groups A-F evoke unique innate immune responses, of which HAd3 and SAd23 are partially complement dependent

Alternative human and non-human Ad serotype vectors are currently studied for gene therapy and/or vaccine applications to capitalize upon their likely ability to avoid pre-existing immunity to HAd5. However, relatively little attention has been given to the nature and scope of innate immune responses generated by alternative Ad serotypes. In this study, we characterized several innate immune responses after intravenous administration of wild-type Ad serotypes HAd31, HAd3, HAd5, HAd37, SAd23 and HAd41, representing groups A-F, respectively. Notably, biodistribution studies revealed significant differences between the serotypes, with high levels of HAd3 genomes found in the liver and lung, and HAd37 genomes found in the spleen after systemic administration. Relative to similar treatments with other Ad serotypes, HAd3 and SAd23 induced altered innate immune responses, illustrated by induction of higher levels of cellular gene transcription in several tissues, and higher plasma levels of cytokines and chemokines. We also investigated whether complement interactions have a role in HAd3- and SAd23-induced responses. We confirmed complement dependent gene transcription, plasma cytokine/chemokine responses, and liver toxicities incurred after administration of HAd3 and SAd23. This study highlights the potential benefits and/or limitations to the proposed use of alternative Ad serotypes for gene therapy or vaccine applications.