Mutations in KCNK4 that Affect Gating Cause a Recognizable Neurodevelopmental Syndrome.

Aberrant activation or inhibition of potassium (K+) currents across the plasma membrane of cells has been causally linked to altered neurotransmission, cardiac arrhythmias, endocrine dysfunction, and (more rarely) perturbed developmental processes. The K+ channel subfamily K member 4 (KCNK4), also known as TRAAK (TWIK-related arachidonic acid-stimulated K+ channel), belongs to the mechano-gated ion channels of the TRAAK/TREK subfamily of two-pore-domain (K2P) K+ channels. While K2P channels are well known to contribute to the resting membrane potential and cellular excitability, their involvement in pathophysiological processes remains largely uncharacterized. We report that de novo missense mutations in KCNK4 cause a recognizable syndrome with a distinctive facial gestalt, for which we propose the acronym FHEIG (facial dysmorphism, hypertrichosis, epilepsy, intellectual disability/developmental delay, and gingival overgrowth). Patch-clamp analyses documented a significant gain of function of the identified KCNK4 channel mutants basally and impaired sensitivity to mechanical stimulation and arachidonic acid. Co-expression experiments indicated a dominant behavior of the disease-causing mutations. Molecular dynamics simulations consistently indicated that mutations favor sealing of the lateral intramembrane fenestration that has been proposed to negatively control K+ flow by allowing lipid access to the central cavity of the channel. Overall, our findings illustrate the pleiotropic effect of dysregulated KCNK4 function and provide support to the hypothesis of a gating mechanism based on the lateral fenestrations of K2P channels.

Age-related sensory neuropathy in patients with spinal muscular atrophy type 1.

INTRODUCTION/AIMS: Spinal muscular atrophy type 1 (SMA 1) is a devastating motor neuron disorder that leads to progressive muscle weakness, respiratory failure and premature death. Although sensory electrophysiological changes have been anecdotally found in pediatric SMA 1 patients, the age of onset of sensory neuropathy remains unknown. METHODS: Sensory nerve conduction studies of the median and sural nerves were performed in 28 consecutive SMA 1 patients of different ages. Sensory nerve conduction velocities and sensory nerve action potential (SNAP) amplitudes recorded in these patients were compared with those obtained from 93 healthy subjects stratified by age. RESULTS: SNAP amplitudes decreased with increasing age in the sural and median nerves, without any significant difference between upper and lower limbs. DISCUSSION: Our data suggest that sural and median nerve SNAP amplitudes are normal in younger patients, while an axonal neuropathy appears in older ones.

Childhood-Onset Multifocal Motor Neuropathy with IgM Antibodies to Gangliosides GM1: A Case Report with Poor Outcome.

BACKGROUND: Multifocal motor neuropathy (MMN) is a slowly progressive motor neuropathy characterized by asymmetric muscle weakness without sensory involvement. Typically, MMN respond completely to treatment with intravenous immunoglobulin (IVIg). MMN is even rarer in the pediatric population, where only five patients have been reported up to now. CASE REPORT: We discuss the 3-year follow-up of a 13-year-old girl with MMN who was positive for IgM antibodies to gangliosides GM1. She was diagnosed with MMN in accordance with the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) criteria. Serological studies revealed that she tested positive for IgM antibodies to GM1. She underwent intravenous methylprednisolone followed by an oral prednisone taper, intravenous immunoglobulin (IVIg), plasma exchange followed by IVIG and prednisone and Rituximab. No improvement was referred. At the present, she shows flaccid tetraplegia, facial diplegia, and bulbar cranial nerve palsy. CONCLUSION: Although childhood onset MMN is rare, most patients reported in literature respond to IVIg treatment. In a few cases, however, IVIg can be ineffective. In our patient, IVIg as well as treatment with prednisolone, plasma exchange and rituximab have failed.

Hereditary spastic paraplegia is a novel phenotype for germline de novo ATP1A1 mutation.

Dominant mutations in ATP1A1, encoding the alpha-1 isoform of the Na+ /K+ -ATPase, have been recently reported to cause an axonal to intermediate type of Charcot-Marie-Tooth disease (ie, CMT2DD) and a syndrome with hypomagnesemia, intractable seizures and severe intellectual disability. Here, we describe the first case of hereditary spastic paraplegia (HSP) caused by a novel de novo (p.L337P) variant in ATP1A1. We provide evidence for the causative role of this variant with functional and homology modeling studies. This finding expands the phenotypic spectrum of the ATP1A1-related disorders, adds a piece to the larger genetic puzzle of HSP, and increases knowledge on the molecular mechanisms underlying inherited axonopathies (ie, CMT and HSP).

Visual pathways evaluation in Kearns Sayre syndrome: a diffusion tensor imaging study.

PURPOSE: Kearns Sayre syndrome (KSS) is a mitochondrial disorder characterized by development of visual impairment. Electroretinogram (ERG) and visual evoked potentials are not able to provide topographical information of optic damage. The purpose of this study was to explore retrochiasmatic optic pathway alteration in KSS with diffusion tractographic analysis and to compare it with different tracts. METHODS: DTI from 8 KSS subjects (14.7 years) and 10 healthy controls (HC) were acquired on a 3T scanner. Optic radiations (OR), optic tracts (OT), inferior frontooccipital fasciculus (IFOF) and corticospinal tract (CST) were reconstructed with probabilistic tractography. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial (RD), and axial diffusivity (AD) were calculated, evaluating group differences. T test on diffusion parameters identified significantly different track portions among cohorts. RESULTS: All patients had optic pathway alterations at electrophysiological examination. Significant lower FA were found in OT, IFOF, and CST of KSS group. RD was significantly higher in bilateral OR, IFOF, CST, and right OT, while ADC was higher in bilateral OR and CST. RD values were higher in the proximal and distal portion of OR bilaterally and in the distal portion of right OT, while widespread differences were found in IFOF and CST. No significant differences were found for AD. FA profiles analysis demonstrated significant differences between groups in several regions of OT, IFOF, and CST, while ADC assessment revealed spread differences in OR and CST. CONCLUSIONS: DTI evaluation of retrochiasmatic tracks may represent a useful tool to topographically investigate retrochiasmatic visual impairment in KSS.

EEG mean frequency changes in healthy subjects during prefrontal transcranial direct current stimulation.

In this pilot study we evaluated electroencephalographic (EEG) mean frequency changes induced by prefrontal transcranial direct current stimulation (tDCS) and investigated whether they depended on tDCS electrode montage. Eight healthy volunteers underwent tDCS for 15 min during EEG recording. They completed six tDCS sessions, 1 wk apart, testing left and right direct current (DC) dipole directions with six different montages: four unipolar montages (one electrode on a prefrontal area, the other on the opposite wrist) and two bipolar montages (both electrodes on prefrontal areas), and a single sham session. EEG power spectra were assessed from four 1-min EEG epochs, before, during, and after tDCS. During tDCS the outcome variable, brain rate (fb), changed significantly, and the changes persisted for minutes after tDCS ended. With the DC dipole directed to the left (anode on the left prefrontal area or wrist), fb increased, and with the DC dipole directed to the right (anode on the right prefrontal area or wrist), fb decreased, suggesting asymmetric prefrontal cortex functional organization in the normal human brain. Anodal and cathodal effects were opposite but equally large. Gender left these effects unchanged.

Spectrum of ERCC6-Related Cockayne Syndrome (Type B): From Mild to Severe Forms.

(1) Background: Cockayne syndrome (CS) is an ultra-rare multisystem disorder, classically subdivided into three forms and characterized by a clinical spectrum without a clear genotype-phenotype correlation for both the two causative genes ERCC6 (CS type B) and ERCC8 (CS type A). We assessed this, presenting a series of patients with genetically confirmed CSB. (2) Materials and Methods: We retrospectively collected demographic, clinical, genetic, neuroimaging, and serum neurofilament light-chain (sNFL) data about CSB patients; diagnostic and severity scores were also determined. (3) Results: Data of eight ERCC6/CSB patients are presented. Four patients had CS I, three patients CS II, and one patient CS III. Various degrees of ataxia and spasticity were cardinal neurologic features, with variably combined systemic characteristics. Mean age at diagnosis was lower in the type II form, in which classic CS signs were more evident. Interestingly, sNFL determination appeared to reflect clinical classification. Two novel premature stop codon and one novel missense variants were identified. All CS I subjects harbored the p.Arg735Ter variant; the milder CS III subject carried the p.Leu764Ser missense change. (4) Conclusion: Our work confirms clinical variability also in the ERCC6/CSB type, where manifestations may range from severe involvement with prenatal or neonatal onset to normal psychomotor development followed by progressive ataxia. We propose, for the first time in CS, sNFL as a useful peripheral biomarker, with increased levels compared to currently available reference values and with the potential ability to reflect disease severity.

A New Case of Autosomal-Dominant POLR3B-Related Disorder: Widening Genotypic and Phenotypic Spectrum.

POLR3B encodes the RPC2 subunit of RNA polymerase III. Pathogenic variants are associated with biallelic hypomyelinating leukodystrophy belonging to the POLR-related disorders. Recently, the association with dominant demyelinating neuropathy, classified as Charcot-Marie-Tooth syndrome type 1I (CMT1I), has been reported as well. Here we report on an additional patient presenting with developmental delay and generalized epilepsy, followed by the onset of mild pyramidal and cerebellar signs, vertical gaze palsy and subclinical demyelinating polyneuropathy. A new heterozygous de novo missense variant, c.1297C > G, p.Arg433Gly, in POLR3B was disclosed via trio-exome sequencing. In silico analysis confirms the hypothesis on the variant pathogenicity. Our research broadens both the genotypic and phenotypic spectrum of the autosomal-dominant POLR3B-related condition.

Neurodevelopmental and genetic findings in neonates with intracranial arteriovenous shunts: A case series.

Background: Despite the latest advances in prenatal diagnosis and postnatal embolization procedures, intracranial arteriovenous shunts (AVSs) are still associated with high mortality and morbidity rates. Our aim was to evaluate the presentation and clinical course, the neurodevelopmental outcome, and the genetic findings of neonates with AVSs. Methods: In this retrospective observational study, medical records of neonates with cerebral AVSs admitted to our hospital from January 2020 to July 2022 were revised. In particular, we evaluated neuroimaging characteristics, endovascular treatment, neurophysiological features, neurodevelopmental outcomes, and genetic findings. Results: We described the characteristics of 11 patients with AVSs. Ten infants (90.9%) required embolization during the first three months of life. In 5/9 infants, pathological electroencephalography findings were observed; of them, two patients presented seizures. Eight patients performed Median Nerve Somatosensory Evoked Potentials (MN-SEPs): of them, six had an impaired response. We found normal responses at Visual Evoked Potentials and Brainstem Auditory Evoked Potentials. Eight patients survived (72.7%) and were enrolled in our multidisciplinary follow-up program. Of them, 7/8 completed the Bayley-III Scales at 6 months of corrected age: none of them had cognitive and language delays; conversely, a patient had a moderate delay on the Motor scale. The remaining survivor patient developed cerebral palsy and could not undergo Bayley-III evaluation because of the severe psychomotor delay. From the genetic point of view, we found a novel pathogenic variant in the NOTCH3 gene and three additional genomic defects of uncertain pathogenicity. Conclusion: We propose SEPs as an ancillary test to discern the most vulnerable infants at the bedside, particularly to identify possible future motor impairment in follow-up. The early identification of a cognitive or motor delay is critical to intervene with personalized rehabilitation treatment and minimize future impairment promptly. Furthermore, the correct interpretation of identified genetic variants could provide useful information, but further studies are needed to investigate the role of these variants in the pathogenesis of AVSs.

Vocal Cord Paralysis and Feeding Difficulties as Early Diagnostic Clues of Congenital Myasthenic Syndrome with Neonatal Onset: A Case Report and Review of Literature.

Herein, we present a newborn female with congenital vocal cord paralysis who required a tracheostomy in the neonatal period. She also presented with feeding difficulties. She was later diagnosed with a clinical picture of congenital myasthenia, associated with three variants of the MUSK gene: the 27-month follow-up was described. In particular, the c.565C>T variant is novel and has never been described in the literature; it causes the insertion of a premature stop codon (p.Arg189Ter) likely leading to a consequent formation of a truncated nonfunctioning protein. We also systematically collected and summarized information on patients' characteristics of previous cases of congenital myasthenia with neonatal onset reported in the literature to date, and we compared them to our case. The literature reported 155 neonatal cases before our case, from 1980 to March 2022. Of 156 neonates with CMS, nine (5.8%) had vocal cord paralysis, whereas 111 (71.2%) had feeding difficulties. Ocular features were evident in 99 infants (63.5%), whereas facial-bulbar symptoms were found in 115 infants (73.7%). In one hundred sixteen infants (74.4%), limbs were involved. Respiratory problems were displayed by 97 infants (62.2%). The combination of congenital stridor, particularly in the presence of an apparently idiopathic bilateral vocal cord paralysis, and poor coordination between sucking and swallowing may indicate an underlying congenital myasthenic syndrome (CMS). Therefore, we suggest testing infants with vocal cord paralysis and feeding difficulties for MUSK and related genes to avoid a late diagnosis of CMS and improve outcomes.

Novel SEPSECS Pathogenic Variants Featuring Unusual Phenotype of Complex Movement Disorder With Thin Corpus Callosum: A Case Report.

OBJECTIVES: To report a novel association between pathogenic variants in the SEPSECS gene and complex movement disorder with thin corpus callosum (TCC). METHODS: Clinical exome sequencing was performed in an adult patient with a genetically unsolved neurodegenerative disorder. The main clinical, neuroimaging, and genetic data were described. RESULTS: The c.865C > T (p.P289S) and c.1297T > C (p.Y433H) missense variants in SEPSECS (NM_016,955.3) were discovered. DISCUSSION: This case represents a novel form of early-onset pyramidal syndrome with optic nerve hypoplasia, which slowly evolved to extrapyramidal syndrome featuring dystonia-parkinsonism, associated with TCC, caused by SEPSECS pathogenic variants. This form enlarges the group of the so-called pyramidal-extrapyramidal syndromes, as well as complex hereditary spastic paraparesis with TCC.

"Atypical" Krabbe disease in two siblings harboring biallelic GALC mutations including a deep intronic variant.

Krabbe disease (KD) is a rare lysosomal storage disorder caused by biallelic pathogenic variants in GALC. Most patients manifest the severe classic early-infantile form, while a small percentage of cases have later-onset types. We present two siblings with atypical clinical and neuroimaging phenotypes, compared to the classification of KD, who were found to carry biallelic loss-of-function GALC variants, including a recurrent 30 kb deletion and a previously unreported deep intronic variant that was identified by mRNA sequencing. This family represents a unique description in the KD literature and contributes to expanding the clinical and molecular spectra of this rare disorder.

Case report: A pediatric case of Bickerstaff brainstem encephalitis after COVID-19 vaccination and Mycoplasma pneumoniae infection: Looking for the culprit.

Bickerstaff brainstem encephalitis (BBE) is a rare, immune-mediated disease characterized by the acute onset of external ophthalmoplegia, ataxia, and consciousness disturbance. It has a complex multifactorial etiology, and a preceding infectious illness is seen in the majority of cases. Immune-mediated neurological syndromes following COVID-19 vaccination have been increasingly described. Here we report the case of a child developing BBE 2 weeks after COVID-19 vaccination. Despite nerve conduction studies and CSF analysis showing normal results, BBE was diagnosed on clinical ground and immunotherapy was started early with a complete recovery. Later, diagnosis was confirmed by positive anti-GQ1b IgG in serum. Even if there was a close temporal relationship between disease onset and COVID-19 vaccination, our patient also had evidence of a recent Mycoplasma pneumoniae infection that is associated with BBE. Indeed, the similarity between bacterial glycolipids and human myelin glycolipids, including gangliosides, could lead to an aberrantly immune activation against self-antigens (i.e., molecular mimicry). We considered the recent Mycoplasma pneumoniae infection a more plausible explanation of the disease onset. Our case report suggests that suspect cases of side effects related to COVID-19 vaccines need a careful evaluation in order to rule out well-known associated factors before claiming for a causal relationship.

Short and Long-Term Toxicity in Pediatric Cancer Treatment: Central Nervous System Damage.

Neurotoxicity caused by traditional chemotherapy and radiotherapy is well known and widely described. New therapies, such as biologic therapy and immunotherapy, are associated with better outcomes in pediatric patients but are also associated with central and peripheral nervous system side effects. Nevertheless, central nervous system (CNS) toxicity is a significant source of morbidity in the treatment of cancer patients. Some CNS complications appear during treatment while others present months or even years later. Radiation, traditional cytotoxic chemotherapy, and novel biologic and targeted therapies have all been recognized to cause CNS side effects; additionally, the risks of neurotoxicity can increase with combination therapy. Symptoms and complications can be varied such as edema, seizures, fatigue, psychiatric disorders, and venous thromboembolism, all of which can seriously influence the quality of life. Neurologic complications were seen in 33% of children with non-CNS solid malign tumors. The effects on the CNS are disabling and often permanent with limited treatments, thus it is important that clinicians recognize the effects of cancer therapy on the CNS. Knowledge of these conditions can help the practitioner be more vigilant for signs and symptoms of potential neurological complications during the management of pediatric cancers. As early detection and more effective anticancer therapies extend the survival of cancer patients, treatment-related CNS toxicity becomes increasingly vital. This review highlights major neurotoxicities due to pediatric cancer treatments and new therapeutic strategies; CNS primary tumors, the most frequent solid tumors in childhood, are excluded because of their intrinsic neurological morbidity.

Reversible encephalopathy induced by cefoperazone: a case report monitored with EEG.

In patients with an impaired state of consciousness, EEG is fundamental, a correct neurological work-up. Cephalosporins have been identified as a case of triphasic waves' (TW) reversible encephalopathy. We report a case of an acute reversible encephalopathy with TWs during treatment with cefoperazone. We report the occurrence and regression of a confusional state with TWs encephalopathy at EEG after the administration of cefoperazone for urinary tract infection in a patient admitted for syncope. In conclusion, cefoperazone should be considered as a cause of toxic encephalopathy with EEG TWs, when there is a temporal relationship with its administration; EEG monitoring is useful in the neurological follow-up.

Non-convulsive status epilepticus characterised exclusively by a language disorder induced by non-ketotic hyperglycaemia.

Non-ketotic hyperglycaemia is an endocrine emergency characterised by elevated blood glucose levels and high plasma osmolarity. While hypoglycaemia-induced seizures are usually generalised, hyperglycaemia-induced seizures are often focal and secondary to the presence of brain lesions. Moreover, in the few studies in which language disorders of epileptic origin have been reported as a clinical manifestation of non-ketotic hyperglycaemia, the disorders were usually not isolated but were followed by partial motor seizures. We describe a patient who presented with non-convulsive partial status epilepticus and whose only sign was a fluctuating language disorder induced by non-ketotic hyperglycaemia. There were no accompanying brain lesions and the patient responded optimally to diazepam. Neurophysiological EEG evaluation was fundamental for the diagnosis.

Brain auditory evoked potentials in pediatric intensive care unit: diagnostic role on encephalopathy and central respiratory failure on infants.

Encephalopathy of different etiologies in infants is often the reason for central respiratory insufficiency which eventually leads patients to the paediatric intensive care unit. Magnetic resonance imaging (MRI) and brainstem auditory evoked potentials (BAEPs) may be useful to identify brainstem alterations among patients with respiratory insufficiency of central origin. MRI is a compulsory technique to identify brain abnormalities, but may fail to detect brainstem lesions of small dimensions. BAEPs play a highly sensitive role on brainstem dysfunction identification because of the generators of different peaks which are related to specific brainstem structures. The early identification of brainstem lesions in mechanically ventilated infants with encephalopathy may reduce the weaning off mechanical ventilation's attempt numbers and provide early informative discussions with families and clinical caregivers about treatment options, such as tracheostomy, long term ventilation and the reduction of their lenght of PICU stay. Furthermore, this would support the evaluation process concerning the affected children, their families and the needs of other social groups, including health systems.

High Intellectual Potential and High Functioning Autism: Clinical and Neurophysiological Features in a Pediatric Sample.

High Intellectual Potential (HIP) and High Functioning Autism (HFA) are two different conditions sharing some clinical and neurobiological features. The aim of the present study was to characterize a sample of HIP children (n: 16; M/F: 14/2; median age: 10 years) in comparison to those with HFA (n: 17; M/F: 16/1; median age: 13 years) and to neurotypically developed (NTD) children (n: 10; M/F: 4/6; median age: 11 years) from a clinical and neurophysiological perspective. Specifically, a standardized clinical assessment of cognitive and adaptive skills, autistic symptoms, executive functions and behavioral features was performed. Moreover, event-related potentials (ERPs) were recorded, referring specifically to the mismatch negativity (MMN) and P300 paradigm. Our data highlighted the presence of similarities between the intellectually gifted individuals and the ones with autism (i.e., a nonhomogeneous intellective profile, an adaptive skills impairment, subthreshold autistic symptoms and increased perfectionism). Interestingly, a distinct neurophysiological characterization between groups came out, with evidence of a reduced MMN amplitude only in the HFA group. Furthermore, no differences within groups in the P300 component emerged. Therefore, our results start to provide a more informative characterization of the HIP phenotype in comparison to those of HFA and NTD, highlighting the potential role of the MMN amplitude index in helping clinicians and researchers to distinguish between HIP and HFA. Nevertheless, further research on the topic is strongly needed.