Hypothalamic hamartoma: epilepsy and neurodevelopmental profiles in a clinical cohort

Objective: We aimed to determine the prevalence of epilepsy and neurodevelopmental disorders, including autism spectrum disorder, in children and adolescents with hypothalamic hamartoma (HH). We also sought to explore the relationship between these neurodevelopmental comorbidities and epilepsy and to establish the predictive value of structural characteristics of the hamartoma itself. Methods: We retrospectively studied a cohort of 62 children with HH, with neuroimaging reviewed at Great Ormond Street Hospital (GOSH) between 2008 and 2018. Clinical records were reviewed, cognitive and language data analysed, and MRI scans studied. Results: We confirmed a high burden of epilepsy (56%), autism (19%) and other neurodevelopmental disorders. Although rates of some neurodevelopmental disorders were significantly higher in those with epilepsy, autistic features and/or early developmental concerns often predated the onset of seizures, in particular generalized seizures, or occurred independently of seizures. We found a significant correlation between certain structural characteristics of the hamartoma itself and both epilepsy and certain neurodevelopmental comorbidities. Significance: These findings suggest that although seizure burden clearly contributes to the cognitive and behavioural phenotypes seen, the hamartoma itself, and particular characteristics of it, are likely to be primary determinants of both the epilepsy and neurodevelopmental profiles. It is also probable that the underlying aetiology, likely genetic, directly contributes to the clinical profile, with epilepsy, neurodevelopmental impairment and the hamartoma itself representing markers of this aetiology. We propose that atypical neurodevelopmental profiles in HH could best be conceptualized as a developmental and epileptic encephalopathy. These findings have implications for counselling, monitoring and treatment.

Australian Clinical Consensus Guideline: The diagnosis and acute management of childhood stroke.

Stroke is among the top 10 causes of death in children and survivors carry resulting disabilities for decades, at substantial cost to themselves and their families. Children are not currently able to access reperfusion therapies, due to limited evidence supporting safety and efficacy and long diagnostic delays. The Australian Clinical Consensus Guideline for the Diagnosis and Acute Management of Childhood Stroke was developed to minimize unwarranted variations in care and document best evidence on the risk factors, etiologies, and conditions mimicking stroke that differ from adults. Clinical questions were formulated to inform systematic database searches from 2007 to 2017, limited to English and pediatric studies. SIGN methodology and the National Health and Medical Research Council system were used to screen and classify the evidence. The Grades of Recommendation, Assessment, Development, and Evaluation system (GRADE) was used to grade evidence as strong or weak. The Guideline provides more than 60 evidence-based recommendations to assist prehospital and acute care clinicians in the rapid identification of childhood stroke, choice of initial investigation, to confirm diagnosis, determine etiology, selection of the most appropriate interventions to salvage brain at risk, and prevent recurrence. Recommendations include advice regarding the management of intracranial pressure and congenital heart disease. Implementation of the Guideline will require reorganization of prehospital and emergency care systems, including the development of regional stroke networks, pediatric Code Stroke, rapid magnetic resonance imaging and accreditation of primary pediatric stroke centers with the capacity to offer reperfusion therapies. The Guideline will allow auditing to benchmark timelines of care, access to acute interventions, and outcomes. It will also facilitate the development of an Australian childhood stroke registry, with data linkage to international registries, to allow for accurate data collection on stroke incidence, treatment, and outcomes.

Mutations in KCNT1 cause a spectrum of focal epilepsies.

Autosomal dominant mutations in the sodium-gated potassium channel subunit gene KCNT1 have been associated with two distinct seizure syndromes, nocturnal frontal lobe epilepsy (NFLE) and malignant migrating focal seizures of infancy (MMFSI). To further explore the phenotypic spectrum associated with KCNT1, we examined individuals affected with focal epilepsy or an epileptic encephalopathy for mutations in the gene. We identified KCNT1 mutations in 12 previously unreported patients with focal epilepsy, multifocal epilepsy, cardiac arrhythmia, and in a family with sudden unexpected death in epilepsy (SUDEP), in addition to patients with NFLE and MMFSI. In contrast to the 100% penetrance so far reported for KCNT1 mutations, we observed incomplete penetrance. It is notable that we report that the one KCNT1 mutation, p.Arg398Gln, can lead to either of the two distinct phenotypes, ADNFLE or MMFSI, even within the same family. This indicates that genotype-phenotype relationships for KCNT1 mutations are not straightforward. We demonstrate that KCNT1 mutations are highly pleiotropic and are associated with phenotypes other than ADNFLE and MMFSI. KCNT1 mutations are now associated with Ohtahara syndrome, MMFSI, and nocturnal focal epilepsy. They may also be associated with multifocal epilepsy and cardiac disturbances.

PRRT2 mutations cause benign familial infantile epilepsy and infantile convulsions with choreoathetosis syndrome.

Benign familial infantile epilepsy (BFIE) is a self-limited seizure disorder that occurs in infancy and has autosomal-dominant inheritance. We have identified heterozygous mutations in PRRT2, which encodes proline-rich transmembrane protein 2, in 14 of 17 families (82%) affected by BFIE, indicating that PRRT2 mutations are the most frequent cause of this disorder. We also report PRRT2 mutations in five of six (83%) families affected by infantile convulsions and choreoathetosis (ICCA) syndrome, a familial syndrome in which infantile seizures and an adolescent-onset movement disorder, paroxysmal kinesigenic choreoathetosis (PKC), co-occur. These findings show that mutations in PRRT2 cause both epilepsy and a movement disorder. Furthermore, PRRT2 mutations elicit pleiotropy in terms of both age of expression (infancy versus later childhood) and anatomical substrate (cortex versus basal ganglia).