Association of novel mutation in TRPV4 with familial nonsyndromic craniosynostosis with complete penetrance and variable expressivity.

OBJECTIVE: The aim of this study was to characterize a novel pathogenic variant in the transient receptor potential vanilloid 4 (TRPV4) gene, causing familial nonsyndromic craniosynostosis (CS) with complete penetrance and variable expressivity. METHODS: Whole-exome sequencing was performed on germline DNA of a family with nonsyndromic CS to a mean depth coverage of 300× per sample, with greater than 98% of the targeted region covered at least 25×. In this study, the authors detected a novel variant, c.496C>A in TRPV4, exclusively in the four affected family members. The variant was modeled using the structure of the TRPV4 protein from Xenopus tropicalis. In vitro assays in HEK293 cells overexpressing wild-type TRPV4 or TRPV4 p.Leu166Met were used to assess the effect of the mutation on channel activity and downstream MAPK signaling. RESULTS: The authors identified a novel, highly penetrant heterozygous variant in TRPV4 (NM_021625.4:c.496C>A) causing nonsyndromic CS in a mother and all three of her children. This variant results in an amino acid change (p.Leu166Met) in the intracellular ankyrin repeat domain distant from the Ca2+-dependent membrane channel domain. In contrast to other TRPV4 mutations in channelopathies, this variant does not interfere with channel activity as identified by in silico modeling and in vitro overexpression assays in HEK293 cells. CONCLUSIONS: Based on these findings, the authors hypothesized that this novel variant causes CS by modulating the binding of allosteric regulatory factors to TRPV4 rather than directly modifying its channel activity. Overall, this study expands the genetic and functional spectrum of TRPV4 channelopathies and is particularly relevant for the genetic counseling of CS patients.

A needs assessment of pediatric epilepsy surgery in Haiti.

OBJECTIVE: Epilepsy disproportionately affects low- and/or middle-income countries (LMICs). Surgical treatments for epilepsy are potentially curative and cost-effective and may improve quality of life and reduce social stigmas. In the current study, the authors estimate the potential need for a surgical epilepsy program in Haiti by applying contemporary epilepsy surgery referral guidelines to a population of children assessed at the Clinique d'Épilepsie de Port-au-Prince (CLIDEP). METHODS: The authors reviewed 812 pediatric patient records from the CLIDEP, the only pediatric epilepsy referral center in Haiti. Clinical covariates and seizure outcomes were extracted from digitized charts. Electroencephalography (EEG) and neuroimaging reports were further analyzed to determine the prevalence of focal epilepsy or surgically amenable syndromes and to assess the lesional causes of epilepsy in Haiti. Lastly, the toolsforepilepsy instrument was applied to determine the proportion of patients who met the criteria for epilepsy surgery referral. RESULTS: Two-thirds of the patients at CLIDEP (543/812) were determined to have epilepsy based on clinical and diagnostic evaluations. Most of them (82%, 444/543) had been evaluated with interictal EEG, 88% of whom (391/444) had abnormal findings. The most common finding was a unilateral focal abnormality (32%, 125/391). Neuroimaging, a prerequisite for applying the epilepsy surgery referral criteria, had been performed in only 58 patients in the entire CLIDEP cohort, 39 of whom were eventually diagnosed with epilepsy. Two-thirds (26/39) of those patients had abnormal findings on neuroimaging. Most patients (55%, 18/33) assessed with the toolsforepilepsy application met the criteria for epilepsy surgery referral. CONCLUSIONS: The authors' findings suggest that many children with epilepsy in Haiti could benefit from being evaluated at a center with the capacity to perform basic brain imaging and neurosurgical treatments.

Assessment and treatment of childhood epilepsy in Haiti.

OBJECTIVE: The global burden of pediatric epilepsy is disproportionately concentrated in low- and middle-income countries (LMICs). However, little is known about the effectiveness of current treatment programs in this setting. We present the outcomes of children who were assessed and treated at the Clinique D'Épilepsie de Port-au-Prince (CLIDEP), the only pediatric epilepsy referral center in Haiti. METHODS: A 10-year retrospective review of children consecutively assessed and treated at CLIDEP was performed. The primary outcome was seizure control following treatment for epilepsy. The secondary outcome was an accurate determination of the diagnosis of epilepsy. A data-driven principle component regression (PCR) analysis was used to identify variables associated with outcomes of interest. RESULTS: Of the 812 children referred for evaluation, most children (82%) underwent electroencephalography to investigate a possible epilepsy diagnosis. Very few children (7%) underwent cranial imaging. Although many patients were lost to follow-up (24%), most children who returned to clinic had less frequent seizures (51%) and compliance with medication was relatively high (79%). Using PCR, we identified a patient phenotype that was strongly associated with poor seizure control which had strong contributions from abnormal neurological examination, higher number of antiepileptic drugs, comorbid diagnoses, epileptic encephalopathy or epilepsy syndrome, and developmental delay. Head circumference also contributed to epilepsy outcomes in Haiti with smaller head sizes being associated with a poor seizure outcome. A dissociable phenotype of febrile seizures, suspected structural abnormality, epileptic encephalopathy or epilepsy syndrome, and higher seizure frequency was associated with a diagnosis of epilepsy. SIGNIFICANCE: We describe the current landscape of childhood epilepsy in Haiti with an emphasis on diagnosis, treatment and outcomes. The findings provide evidence for the effectiveness of programs aimed at the diagnosis and management of epilepsy in LMICs and may inform the allocation of resources and create more effective referral structures.

Eight-Year Experience With 3-T Intraoperative MRI Integration in Focal Pediatric Epilepsy Surgery: Impact on Extent of Resection, Residual Volumes, and Seizure Outcomes.

OBJECTIVE. The purpose of this study was to investigate the influence of 3-T intraoperative MRI (ioMRI) on the extent of resection of pediatric focal epileptogenic lesions, residual lesion volumes, and postoperative seizure outcomes. MATERIALS AND METHODS. All surgical procedures for focal epilepsy from 2003 to 2017 were retrospectively reviewed. Patients were divided into two groups: those who underwent ioMRI and those who did not. Each group was subdivided into two subcategories according to preoperative MRI visualization of the lesion: those with well-defined and those with poorly defined lesions. The volumes of preoperative lesions and postoperative residual lesions were delineated. Outcome data and patient characteristics were reviewed. The results were compared between the two groups and the two subcategories. RESULTS. Eighty patients were included: 45 in the ioMRI group (24 with well-defined lesions, 21 with poorly defined lesions) and 35 in the non-ioMRI group (18 with well-defined lesions, 17 with poorly defined lesions). The well-defined lesions included tumors and vascular lesions. The poorly defined lesions included malformations of cortical development, hippocampal sclerosis, and tuberous sclerosis. The mean follow-up duration was 5.1 ± 3.3 years. The rate of gross total resection was not significantly different between the ioMRI and non-ioMRI groups (p = 0.46). However, ioMRI findings facilitated further resection during surgery, increasing gross total resection by an additional 11.1%. The ioMRI group had a significant reduction in percentage of residual volume (p < 0.001). Outcome data suggested that ioMRI is protective against poor Engel score (p = 0.048). Although ioMRI prolonged the mean operative time by 1.2 hours (p = 0.002), the additional time was not associated with additional complications. CONCLUSION. Integration of ioMRI into focal epilepsy surgery was associated with smaller residual lesions and was protective against poor Engel score. It prolonged the operative time but without increasing the number of complications.

Thalamostriatal degeneration contributes to dystonia and cholinergic interneuron dysfunction in a mouse model of Huntington's disease.

Huntington's disease (HD) is an autosomal dominant trinucleotide repeat disorder characterized by choreiform movements, dystonia and striatal neuronal loss. Amongst multiple cellular processes, abnormal neurotransmitter signalling and decreased trophic support from glutamatergic cortical afferents are major mechanisms underlying striatal degeneration. Recent work suggests that the thalamostriatal (TS) system, another major source of glutamatergic input, is abnormal in HD although its phenotypical significance is unknown. We hypothesized that TS dysfunction plays an important role in generating motor symptoms and contributes to degeneration of striatal neuronal subtypes. Our results using the R6/2 mouse model of HD indicate that neurons of the parafascicular nucleus (PF), the main source of TS afferents, degenerate at an early stage. PF lesions performed prior to motor dysfunction or striatal degeneration result in an accelerated dystonic phenotype and are associated with premature loss of cholinergic interneurons. The progressive loss of striatal medium spiny neurons and parvalbumin-positive interneurons observed in R6/2 mice is unaltered by PF lesions. Early striatal cholinergic ablation using a mitochondrial immunotoxin provides evidence for increased cholinergic vulnerability to cellular energy failure in R6/2 mice, and worsens the dystonic phenotype. The TS system therefore contributes to trophic support of striatal interneuron subtypes in the presence of neurodegenerative stress, and TS deafferentation may be a novel cell non-autonomous mechanism contributing to the pathogenesis of HD. Furthermore, behavioural experiments demonstrate that the TS system and striatal cholinergic interneurons are key motor-network structures involved in the pathogenesis of dystonia. This work suggests that treatments aimed at rescuing the TS system may preserve important elements of striatal structure and function and provide symptomatic relief in HD.

Hydrocephalus-induced neurogenic stunned myocardium and cardiac arrest in a child: completely reversed with CSF diversion.

Neurogenic stunned myocardium (NSM) is a potentially fatal cause of sudden cardiogenic dysfunction due to an acute neurological event, most commonly aneurysmal subarachnoid hemorrhage in adults. Only two pediatric cases of hydrocephalus-induced NSM have been reported. Here the authors report a third case in a 14-year-old boy who presented with severe headache, decreased level of consciousness, and shock in the context of acute hydrocephalus secondary to fourth ventricular outlet obstruction 3 years after standard-risk medulloblastoma treatment. He was initially stabilized with the insertion of an external ventricular drain and vasopressor treatment. He had a profoundly reduced cardiac contractility and became asystolic for 1 minute, requiring cardiopulmonary resuscitation when vasopressors were inadvertently discontinued. Over 1 week, his ventricles decreased in size and his cardiac function returned to normal. All other causes of heart failure were ruled out, and his impressive response to CSF diversion clarified the diagnosis of NSM secondary to hydrocephalus. He was unable to be weaned from his drain during his time in the hospital, so he underwent an endoscopic third ventriculostomy and has remained well with normal cardiac function at more than 6 months' follow-up. This case highlights the importance of prompt CSF diversion and cardiac support for acute hydrocephalus presenting with heart failure in the pediatric population.

Neurofibromatosis Type 1: Description of a Novel Diagnostic Scoring System in Pediatric Optic Nerve Glioma.

OBJECTIVE: Neurofibromatosis type 1 (NF1) is a multisystemic genetic disease in which patients develop benign tumors including optic nerve gliomas (ONG). Optic nerve thickening and tortuosity are radiologic markers of tumors but can also be present in children with NF1 who do not have gliomas, thus complicating screening and diagnosis. We undertook this study to retrospectively determine quantitative and qualitative diagnostic criteria using MRI of the orbits for ONG in children with NF1. MATERIALS AND METHODS: MR images of the orbits obtained from 2003 to 2016 for children with and without NF1 were reviewed. Optic nerves were divided into three groups: NF1 with glioma (n = 71 nerves), NF1 without glioma (n = 151 nerves), and healthy control subjects (n = 66 nerves). The diameter of each nerve was measured at multiple locations. Two radiologists assessed tortuosity using validated criteria, and subarachnoid dilatation was quantified. Last, a composite score using both optic nerve diameter and tortuosity was proposed. RESULTS: The mean diameter of the optic nerve was significantly larger in patients with NF1 with glioma compared with those with NF1 without glioma and with control subjects at all locations. Maximal nerve diameter greater than 2 SD above the mean maximal diameter for control nerves was considered abnormally enlarged. The tortuosity parameters were all significantly associated with ONG compared with absence of ONG in NF1. A scoring system derived from these data were highly reliable in differentiating ONG from absence of ONG in NF1. CONCLUSION: The radiologic diagnosis of ONG in patients with NF1 is challenging. The scoring systems we describe provide a framework for simple radiologic criteria for ONG in these patients.