Background: Dravet syndrome and genetic epilepsy with febrile seizures plus (GEFS+) are associated with pathogenic variants in SCN1A. While most such cases are heterozygous, there have been 16 reported homozygous cases. We report two new biallelic cases associated with divergent phenotypes.Methods: We performed a chart review for two patients with different homozygous SCN1A variants and reviewed all previously published biallelic SCN1A pathogenic variants. Results: Our first patient exhibited early afebrile seizures and severe developmental delay, without febrile seizures or status epilepticus. A homozygous c. 1676T>A, (p. Ile559Asn) variant of uncertain significance was identified, carried by asymptomatic parents. The second patient exhibited early, recurrent, and prolonged febrile seizures, moderate developmental delay, and motor dysfunction; a homozygous pathogenic c. 4970G>A, (p. Arg1657His) variant carried by asymptomatic parents was identified.

Of 18 known cases of biallelic SCN1A pathogenic variants, 15/18 (83%) have diagnoses of Dravet or GEFS+. The remaining 3/18 (17%) had pharmacoresponsive epilepsy with prominent GDD. Cognitive phenotypes ranged from intact neurodevelopment to profound developmental delay. Eleven out of 18 cases (61%) had motor concerns. Conclusions: These cases expand the phenotypic spectrum of biallelic SCN1A variants. While some patients present typically for Dravet/GEFS+, others present with developmental delay and controllable epilepsy.

Background: Increased availability of genetic testing has led to increased burden of follow up of variants of uncertain significance (VUS). As of January 2025, 327 VUS were identified patients at BC Children’s Hospital. We propose a pipeline to triage and follow up of patients with identified VUS to clarify diagnosis through paternal testing. Methods: Of the 327 patients with VUS, 13 patients with high clinical suspicion for a genetic disorder were identified by their neurologist. Initial chart review for each patient was performed. Clinical phenotype data and the patient’s variant were inputted into the online tool Franklin. This program generates a variant interpretation based on 17/ 28 criteria in ACMG scoring. For each patient the variant would be assumed to be de novo in order to determine if parental testing could change variant classification. Results: 5/13 of the patients had suggested reclassification of variants. 6/13 of the patients would have reclassification of variant to likely pathogenic/pathogenic if the variant was found to be de novo, suggesting a need for paternal testing. Conclusions: This highlights a novel clinical pipeline to improve expediency and triaging of VUS reclassification for paternal testing in epilepsy genomics.

Background: Although the history of the ketogenic diet dates back centuries, with the advancement of anti-seizure medications, the use of the diet for epilepsy declined. It was not until the early 1990s that there was a resurgence of the diet as an adjunct therapy to anti-seizure medication. In 1998, the Montreal Children’s Hospital introduced the ketogenic diet to a child with drug resistant epilepsy. Shortly after, a presentation of the ketogenic diet at hospital Grand Rounds met much skepticism. However, over time the diet has developed into a well-established treatment option for children with drug resistant epilepsy. Two hundred children have since utilized the diet at the Montreal Children’s Hospital. Methods: A review of patient files since the initiation of the program was undertaken. Data was extracted regarding adverse effects, common errors in both hospital and home setting, risks for unfavorable outcomes and parental concerns Results: The development of a rigorous protocol has reduced potential adverse effects, inadvertent complications from errors have improved and parent satisfaction enhanced. Conclusions: This poster will demonstrate how an interdisciplinary approach for a ketogenic diet protocol, involving an advanced Practice Nurse, nutritionist, neurologist and parent, resulted in improved care.

Background: Ketogenic diet can be an effective alternative therapy for medication refractory infantile spasms. Infantile spasms are more prevalent in children with Down syndrome compared with the general population and often medication refractory. Methods: Charts of infants who presented to the Children’s Hospital of Eastern Ontario with Down syndrome and refractory infantile spams treated with ketogenic diet from 2012 to 2025 were reviewed. Clinical response defined by cessation of epileptic spasms and resolution of hypsarrhythmia. Diet ratio,tolerance, side effects, concomitant medications, and diagnostic tests were evaluated. Results: 5 infants were treated with ketogenic diet after failing first line anticonvulsant mendications: viagabatrin and corticosteriods. Ketogenic diet was viable only via G-tube in 1 patient and by NG tube in 3 due to risk of aspiration. Diet was compatible with second line anticonvulsants. Complete electroclinical response occurred in 2 infants after 4 weeks. Partial seizure reduction and electrographic improvement was observed in 1 infant. 1 patient died due to unrelated respiratory illness. Conclusions: Ketogenic diet is a viable potentially effective therapeutic option for infants with Down syndrome and medication refractory infantile spasms. These infants present challenges inherent of Down syndrome such as hypotonia, higher risk for aspiration which need to be considered before diet introduction.

Background: Ontario and other Canadian provinces fund multi-gene sequencing panels as the initial testing approach for patients with epilepsy. However, genetic testing guidelines issued by the US-based National Society for Genetic Counselors and endorsed by the American Epilepsy Society recommend exome as a first-line test. We explored the theoretical improvements in diagnostic yield when selecting exome over provincially-funded panels (PFPs). Methods: Our comparative analysis used a list of 768 diagnostic genes and 4474 diagnostic variants identified in diagnostic exome cases involving clinical indications of seizure. We compared these lists to the genes included in two PFPs (190 genes and 474 genes) to see which exome-identified genes and variants would have been captured by the PFPs. Results: Most exome-identified diagnostic genes may have been missed by the PFPs (82% and 65% for the 190 and 474-gene PFPs), and close to half of the exome-identified diagnostic variants (62% and 43% for the 190 and 474-gene PFPs) may have been missed. Conclusions: Exome-based testing captures a broader range of diagnostic genes and more diagnostic variants than PFPs. The adoption of exome over panels as a first-line test may lead to improved diagnostic rates and permit earlier treatment for individuals with seizures.

Background: In Canada, individuals with intellectual disabilities (ID) make up approximately 25% of the epilepsy population. Despite making up only a small portion, adult hospitalization data in Canada shows that individuals with ID are significantly more likely to be seen in the ED, be hospitalized, and to die as a result of epilepsy and epilepsy complications, than individuals with typical cognitive development. Data looking at ED visits in adolescents with epilepsy and varying cognitive abilities is extremely limited. Methods: To address this, a retrospective chart review of 122 adolescents (42 MID and 80 typical cognitive development) with epilepsy between the ages of 14 and 18 was done. Results: Results showed that adolescents with typical cognitive development had significantly more ED visits (p=.006), and seizure related ED visits (p= .008) than adolescents with MID. Despite the reasons for ED visits not significantly differing between the two groups, adolescents with MID had significantly longer ED visits (p=.023). Finally, when looking exclusively at the MID group, results showed that females were significantly more likely to be seen at the ED than males (p=.001). Conclusions: Results suggest that ED visit frequencies differ among adults and adolescents with ID, potentially suggesting the presence of unique protective factors for adolescents.

Background: Status dystonicus is characterized by frequent or prolonged severe episodes of generalized dystonia. The phenomenology, etiology, and outcome is heterogenous and poorly characterized, making a standardized management approach challenging. We characterized demographics of children with status dystonicus in British Columbia admitted to the pediatric intensive care unit (PICU), management patterns, and outcomes. Methods: Clinical records at our PICU were searched via ICD-10 codes. We included cases admitted 2014-2024 who had dystonia severity grade 3-5, dystonia worse than baseline, and age >30 days old. Results: Seventy-nine records were screened; 41 admissions from 19 unique patients were included. Mean age was 7.6±4.2 years; 53% were female. Most unique patients had a genetic etiology (n=8, 42%). The presenting complaint per admission was often not dystonia (n=24, 59%); infection was the most common trigger (n=23, 56%) followed by pain (n=6, 15%). Patients received several anti-dystonia medications (mean 6.9±2.5), including clonidine, benzodiazepines, ketamine, and others. Mean PICU stay was 11.0±10.8 days; 37% had multiple PICU admissions. Two patients (4.9%) died from status dystonicus complications. Conclusions: Status dystonicus is a life-threatening emergency commonly triggered by pain and infection in patients with dystonia. Given the considerable morbidity and mortality, multi-disciplinary teams should consider standardized treatment guidelines for these complex patients.

Background: We summarize the efficacy and safety data for omaveloxolone in patients with Friedreich ataxia from the MOXIe clinical trial (NCT02255435, EudraCT2015-002762-23) and post hoc analyses. Methods: In MOXIe Part 2, patients aged 16-40 were randomized 1:1 to receive omaveloxolone 150 mg or placebo. The primary outcome was change in modified Friedreich Ataxia Rating Scale (mFARS) from baseline to Week 48—patients could roll over into an open-label extension (OLE). A post hoc propensity-matched analysis compared treated and untreated patients over 3 years. Results: Treatment with omaveloxolone significantly improved mFARS relative to placebo at Week 48, with a difference of -2.41 points for the full analysis set (n=82 [excluding severe pes cavus]; p=0.01) and -1.93 points for the all-randomized population (n=103 [including severe pes cavus]; p=0.03). Transient and reversible changes in aminotransferase levels were observed with omaveloxolone without other signs of liver injury. Headache, nausea, and fatigue were among the more common adverse drug reactions in omaveloxolone-treated patients. In a post hoc propensity-matched analysis, omaveloxolone-treated patients in the OLE progressed by 3 points at Year 3 versus 6.6 points in an untreated matched cohort. Conclusions: Patients who received omaveloxolone showed a significantly stabilized neurological function and slowing of FA progression, as measured by mFARS.

Background: Transcranial doppler ultrasound (TCD) in a pediatric neurocritical setting can determine cerebral hemodynamics by assessing the blood flow velocity in main cerebral arteries. In large vessel occlusions (LVO) that require endovascular thrombectomy (EVT), TCD can monitor recanalization and arterial re-occlusion. We describe one case in a previously healthy 13-year-old girl with a right M1 middle cerebral artery occlusion. Methods: Analysis was done via a retrospective case review. Results: Our patient underwent a successful endovascular thrombectomy (EVT) six hours after symptom onset. Follow up TCDs done at 4, 8, and 24 hours showed stable peak systolic velocities (PSV) on the narrowing of right M1 ranging from 245 to 270 cm/s with stable pre-stenotic PSV around 110 cm/s, indicating focal and stable narrowing of M1 without reocclusion. No high transient signals (HITS) were identified on sub 10 minute TCDs. An urgent echocardiogram revealed a bicuspid aortic valve with vegetations, with later confirmation of infective endocarditis. The patient made an impressive recovery with only mild deficits. Conclusions: TCD can be an effective tool in a pediatric neurocritical setting in guiding initial recanalization after EVT and monitoring for arterial re-occlusion, HITS and hyperperfusion. TCD monitoring also decreases the amount of radiation exposure via CTA.

Background: Acute Necrotizing Encephalopathy of Childhood (ANEC) is an illness characterized by rapidly progressive encephalopathy, typically associated with a precipitating viral illness such as influenza. It is diagnosed clinically and through neuroimaging showing symmetric multifocal lesions involving the deep grey matter, especially the thalamus. Morbidity and mortality in ANEC are high, so prompt recognition and treatment are key, but treatment protocols vary. We propose a management protocol based on a consensus approach and available evidence. Methods: A rapid literature review was conducted. Studies included were meta-analyses, case series, and expert consensus guidelines. Individual case reports were excluded. We identified interventions which have been used, and selected those with evidence or expert support for use in a protocol. The protocol was reviewed with stakeholders in pediatric neurology and PICU. Results: Reported treatments include high-dose steroids, IV immunoglobulins, tocilizumab, and plasmapheresis. The treatment with strongest evidence is high-dose steroids started within 24 hours of presentation. There is frequently reported use of IV immunoglobulins and plasmapheresis, and growing evidence to support use of tocilizumab (IL-6 blockade) within the first 48 hours. Conclusions: Overall, there is strong expert opinion that treatment should be initiated promptly. We present our centre’s protocol to expedite this treatment.

Background: Duchenne muscular dystrophy (DMD) typically presents with painless weakness which may contribute to its delayed recognition. Methods: Retrospective chart review was performed for patients with DMD at CHEO over 15 years (2009-2023). Our data will later be combined with that from two other centers. Inclusion criteria: 1) confirmed DMD; 2) symptom onset <6 yo. Exclusion criteria: incomplete records or family history of DMD. Results: We identified 72 DMD patients. Total of N=49 were analyzed. Subjects were excluded for: incomplete data N=10 (e.g. diagnosis at another centre); symptom onset ≥6 yo (N=4); family history (N=9). First symptoms were reported at a mean age of 2.7 yo (range: 0-5.9 yo) with diagnosis at mean age of 5.2 yo (range: 0.5 to 9.6 yo), representing a mean delay of 2.5 years (range: 0-6.8 yrs). Initial symptoms included: weakness (61.2%), sports difficulty (61.2%), calf pseudohypertrophy (10.2%), language difficulties (8.2%) or muscle pain (2.0%). Learning disability was reported in 36 (73.5%) subjects with 7 (14.3%) having autistic spectrum disorder. Conclusions: The mean delay to diagnosis of patients followed at our centre was similar to the United Kingdom (MDSTARnet). We advocate for increased education to identify DMD earlier, particularly given emerging therapies for this disorder.

Background: Congenital myopathies (CM) are inherited muscle disorders historically classified according to features seen on muscle biopsy and congenital-onset weakness and hypotonia. The aim of our study was to evaluate the benefit of genetic testing, muscle biopsy, NCS/EMG and muscle MRI in obtaining a definite diagnosis for these patients. Methods: A retrospective chart review of all patients diagnosed at a single tertiary-care pediatric hospital over 15 years (2008-2022). REB approval was obtained. Results: Over a period of 15 years, 42 patients with CM were included. All (100%) had genetic testing (i.e. gene panel, WES), 65.9% had muscle biopsy, 67.5% had NCS/EMG and 20% had a muscle MRI. Definite diagnosis was obtained in 38% by genetic testing only, while 42.8% had a diagnosis made by genetic testing supported by the findings of one or more of the other diagnostic tools. Conclusions: Early diagnosis of CM is still essential in congenital myopathies to provide optimal care. Genetic testing is the gold standard for diagnosis, but other diagnostic tools remain valuable in the case of variants of unclear significance.

Background: Nipocalimab (a fully human, effectorless anti-neonatal Fc receptor (FcRn) monoclonal antibody) may ameliorate gMG disease manifestations by selectively targeting FcRn IgG recycling and lowering IgG, including pathogenic autoantibodies in generalized myasthenia gravis (gMG). The objective was to evaluate the effectiveness and safety of intravenous nipocalimab added to background standard-of-care therapy in adolescents with gMG. Methods: Seropositive patients (12-<18 years) with gMG (MGFA Class II-IV) on stable therapy but inadequately controlled, were enrolled in a 24-week open label study. Nipocalimab was administered as a 30 mg/kg IV loading dose followed by 15 mg/kg IV every 2 Weeks. Results: Seven adolescents were enrolled; 5 completed 24-weeks of dosing. The mean(SD) age was 14.1(1.86) years; seven were anti-AChR+, six were female. Mean(SD) baseline MG-ADL/QMG scores were 4.29(2.430)/12.50(3.708). Nipocalimab showed a significant reduction in total serum IgG at week-24; the mean(SD) change from baseline to week-24 for total serum IgG was -68.98%(7.561). The mean(SD) change in MG-ADL/QMG scores at week-24 was -2.40(0.418)/-3.80(2.683); 4 of 5 patients achieved minimum symptom expression (MG-ADL score 0-1) by week-24. Nipocalimab was well-tolerated; there were no serious adverse events. There were no clinically meaningful laboratory changes. Conclusions: Nipocalimab demonstrated efficacy and safety in this 6-month trial in seropositive adolescents with gMG.

Background: Spinal muscular atrophy (SMA) is caused by biallelic mutations in the SMN1 gene. Early diagnosis through newborn screening (NBS) and presymptomatic treatment optimize health outcomes. Methods: SMA-NBS began in Alberta on 28February2022. A multiplex quantitative PCR assay detected homozygous deletions of exon 7 in dried blood spot samples. Screen-positive infants underwent genetic confirmation by multiplex ligation-dependent probe amplification to determine SMN1/SMN2 copy numbers. We report clinical outcomes of SMA diagnoses through Alberta NBS over 3 years. Results: From 28February2022-31December2024, twelve infants were confirmed SMA positive, including two with 2 SMN2 copies and six with 3 SMN2 copies. Median age at initial positive screen was 6 days (range=3-9), and at diagnosis, 15 days (range=11-27). Seven infants (median age=29 days, range=18-142) received onasemnogene abeparvovec-xioi. Two received nusinersen (Day 22) or risdiplam (Day 72), followed by onasemnogene abeparvovec-xioi (Day 48 and 111, respectively). Two infants received risdiplam after 3 months of age. One infant was symptomatic at treatment initiation. Post-treatment evaluations showed ongoing motor milestone achievements. Conclusions: SMA incidence in Alberta during 2022-2024 was 8.2 (95%CI: 3.5-12.8) cases per 100,000 live births. Efforts continue to shorten age at treatment initiation, especially for those with two SMN2 copies, and to promote uniform coverage for 4-copy cases.

Background: Body image research in young people with physical disabilities like cerebral palsy (CP) has received very little attention. The goal of this pilot study is to ask youth with CP (of all levels of disability) directly about body image to learn their perspective. Methods: Our study includes quantitative data of quality-of-life measures, along with qualitative interview data summarized via thematic analysis. Our data is augmented with input from siblings (without CP) of our primary participants to represent a control group in the same family unit. Results: Twelve youths with CP (7 male, 5 female) participated in the study. Withe the higher score representing more positive the body image, scores averaged 17.93/25 (SD 4.73) for those with CP, 18.62/25 (SD 5.45) for those without CP. There were higher scores for males and those ≤13yo compared to 14-18yo. Interview thematic analysis uncovers themes of functional capability, the wish to reduce burden on family, pride in the CP identity, and mixed desirability of media representation. Conclusions: There is greater difference between age groups and genders than there is between those with CP and not. Interviews with participants revealed the important recurring theme of functional capacity connected to positive self-image, which may be considered justification for interventions.

Background: Inuit children have been observed to have high rates of macrocephaly, which leads to burdensome travel for medical evaluation, often with no pathology identified. Given reports that WHO growth charts may not reflect all populations, we compared head circumference (HC) measurements in a cohort of Inuit children with the WHO charts. Methods: We extracted HC data from a retrospective cohort study where, with Inuit partnership, we reviewed medical records of Inuit children, born between 2010-2013, and residing in Nunavut. We excluded children with preterm birth, documented neurologic/genetic disease, and most congenital anomalies. We compared HC values with the 2007 WHO charts. Results: We analyzed records of 1960 Inuit children (8866 data points). Most data were from ages 0-36 months. At all age points, the cohort had statistically significantly larger HC than WHO medians. At age 12 months, median HC were 1.3 cm and 1.5 cm larger for male and female Inuit children. Using WHO growth curves, macrocephaly was overdiagnosed and microcephaly underdiagnosed. Conclusions: Our results support the observation that Inuit children from Nunavut have larger HCs, and use of the WHO charts may lead to overdiagnosis of macrocephaly and underdiagnosis of microcephaly. Population specific growth curves for Inuit children should be considered.

Background: Trofinetide is approved for the treatment of Rett syndrome (RTT) in patients aged ≥2 years. Here, we present the benefits and tolerability of trofinetide in the treatment of RTT with the 12-month follow-up of LOTUS. Methods: Caregivers of patients who are prescribed trofinetide under routine clinical care are eligible to participate. Assessments include the Behavioral Improvement Questionnaire (BIQ), the Quality-of-Life Inventory-Disability (QI-Disability) Questionnaire, and the Gastrointestinal Health Questionnaire. Due to ongoing enrollment, data are reported to 9 months since the initiation of trofinetide. Results: In total, 192 patients were included. The median dose reported at week 1 was 45.0% of the target weight-banded label dose; by week 9 onwards, the median dose was at least 80.0% of the target weight-banded label dose. Behavioral improvements reported with the BIQ were nonverbal communication (49–62%), alertness (43–62%), and social interaction/connectedness (32–52%). The QI-Disability Questionnaire median total scores indicated overall improvement in quality of life (QoL) with trofinetide. Caregivers reported that patients were most likely to void normal stools over the follow-up; most reports of diarrhea were contained inside the patient’s diaper. Conclusions: Caregivers of patients with RTT in LOTUS reported behavioral improvements of RTT symptoms and improvement in patients’ QoL.

Background: Trofinetide is approved for the treatment of Rett syndrome (RTT) in patients aged ≥2 years. Here, we present the benefits and tolerability of trofinetide in pediatric and adult patients with RTT from the LOTUS study. Methods: Caregivers of patients who are prescribed trofinetide under routine clinical care are eligible to participate. This subgroup analysis of the 12-month follow-up of LOTUS focused on pediatric (0–17 years of age) and adult (≥18 years of age) patient populations. Due to ongoing enrollment, data are reported to 9 months since the initiation of trofinetide. Results: In total, 117 pediatric and 74 adult patients were included. The median dose reported at week 1 was 45.0% and 41.0% of the target weight-banded label dose for pediatric and adult patients, respectively; by week 8, the median dose was at least 86.0% and 70.0% of target, respectively. Behavioral improvements included nonverbal communication (pediatric: 53–64%; adult: 41–58%), alertness (pediatric: 50–69%; adult: 33–65%), and social interaction/connectedness (pediatric: 36–58%; adult: 26–46%). Most reports of diarrhea were contained inside the patients’ diapers. Conclusions: Caregivers of pediatric and adult patients with RTT in LOTUS reported improvements consistent with the general population of the study.

Background: MLASA (myopathy, lactate acidosis and sideroblastic anemia) is a rare autosomal recessive mitochondrial disorder, which affects oxidative phosphorylation and iron metabolism in skeletal muscle and bone marrow. Three genes have been identified so far, PUS1 is the most common, followed by YARS2 and MT-ATP6. We present a patient with a novel variant in YARS2 and a literature review. Methods: We report a 20-months-old girl with ptosis and low birth weight. She presented with delayed motor milestones and bulbar weakness with feeding difficulties. She had mild anemia and elevated lactate, echocardiogram revealed a mild to moderate left ventricular hypertrophy without LVOT obstruction. Results: Genetic testing showed two heterozygous variants in YARS2. The maternal one (c.948G>T, p. Arg316Ser) has been reported previously in a compound heterozygous state, while the paternal one (c.917T>C, p.Phe306Ser) has not been previously described. Genetic findings were supported by enzyme activities, which showed reduced complex I+III and complex IV activities and reduced cytochrome oxidase (COX). Conclusions: In this case report we describe a 20-months-old girl with clinical features of MLASA. A novel variant in the YARS2 gene was found, pathogenicity could be proven with clinical phenotype and enzyme activity testing.

Background: Rett Syndrome (RTT) is an X-linked neurodevelopmental disorder, characterized by gradual loss of motor, verbal and social skills. This study describes the epidemiology and healthcare resource utilization (HCRU) of RTT in Ontario, Canada. Methods: RTT patients (≥ one ICD-10-CA code F84.2) were identified using data held at the Institute for Clinical Evaluative Sciences (ICES), between September 2018-August 2023. Incidence and prevalence rates from Ontario were extrapolated nationally using the Stats Can population estimates. Results: A total of 246 patients were indexed; 95% female, median age 21 years and 40% from central Ontario. There were 57 incident and 257 prevalent RTT cases identified in Ontario. National extrapolations estimated 175 incident and 613 prevalent RTT cases. Common comorbidities included developmental disability (85.4%) and epilepsy (49.6%). Patients frequently had outpatient visits (primary care 96.7%, specialists 86.6%), emergency department visits (76.8%) and inpatient hospitalizations (54.5%). Most patients (95.1%) had at least one public claim for all-cause medication. Disease-specific medication claims were for anti-infectives (69.1%) and anti-seizure medications associated with mood effects (65.0%). Conclusions: This study provides population-based estimates of RTT in Canada. Findings highlight the high burden of illness and HCRU of RTT and the opportunities to improve healthcare outcomes in this population.