Search Results (2,649)

Neuronal synapses are the functional units of communication in the central nervous system. This review describes the molecular mechanisms regulating synaptic transmission, plasticity, and circuit refinement. At the presynaptic active zone, scaffolding proteins including bassoon, piccolo, RIMs, and munc13 organize vesicle priming and the localization of voltage-gated calcium channels. Neurotransmitter release is mediated by the SNARE complex, comprising syntaxin-1, SNAP25, and synaptobrevin, and triggered by the calcium sensor synaptotagmin-1. Following exocytosis, synaptic vesicles are recovered through clathrin-mediated, ultrafast, bulk, or kiss-and-run endocytic pathways. Postsynaptically, the postsynaptic density (PSD) serves as a protein hub where scaffolds such as PSD-95, shank, homer, and gephyrin anchor excitatory (AMPA, NMDA) and inhibitory (GABA-A, Glycine) receptors are observed. Synaptic strength is modified during long-term potentiation (LTP) and depression (LTD) through signaling cascades involving kinases like CaMKII, PKA, and PKC, or phosphatases such as PP1 and calcineurin. These pathways regulate receptor trafficking, Arc-mediated endocytosis, and actin-dependent remodeling of dendritic spines. Additionally, synapse formation and elimination are guided by cell adhesion molecules, including neurexins and neuroligins, and by microglial pruning via the complement cascade (C1q, C3) and “don’t eat me” signals like CD47. Molecular diversity is further expanded by alternative splicing and post-translational modifications. A unified model of synaptic homeostasis is required to understand the basis of neuropsychiatric and neurological disorders. Full article

Background and Clinical Significance: Adams–Oliver syndrome type 3 (AOS3) is a rare congenital disorder typically characterised by terminal transverse limb defects and variable involvement of other organ systems. Although pathogenic variants in RBPJ are well established in AOS3, associated neurodevelopmental or psychiatric features have been only sporadically documented. Case Presentation: We describe a male patient first evaluated at the age of 10 years and subsequently re-evaluated at 14 years, with AOS3 presenting terminal limb defects together with autistic-like behaviour, cognitive difficulties, dyslexia, and recurrent depressive symptoms. Whole-exome sequencing (WES) identified a heterozygous pathogenic variant in RBPJ (c.505A>G; p.Lys169Glu), confirming the molecular diagnosis of autosomal dominant AOS3. Additional findings included a heterozygous missense variant in CACNA1A (p.Arg1678Cys), a gene linked to neurological disorders with broad phenotypic variability. Because of elevated homocysteine levels, the patient was also tested for MTHFR variants and was found to be heterozygous for C677T and A1298C. Conclusions: This case illustrates a rare combination of a validated AOS3-associated RBPJ variant, along with additional CACNA1A and MTHFR variants that may influence the patient’s neurocognitive and psychiatric characteristics. The results underscore the importance of comprehensive genetic testing in atypical AOS presentations and highlight the complexity of interpreting overlapping genetic factors. Full article

Background: ALG13-CDG is an X-linked N-linked glycosylation disorder caused by pathogenic variants in the glycosyltransferase ALG13, leading to severe neurological manifestations. Despite the clear CNS involvement, the impact of ALG13 dysfunction on human brain glycosylation and neurodevelopment remains unknown. We hypothesize that ALG13-CDG causes brain-specific hypoglycosylation that disrupts neurodevelopmental pathways and contributes directly to cortical network dysfunction. Methods: We generated iPSC-derived human cortical organoids (hCOs) from individuals with ALG13-CDG to define the impact of hypoglycosylation on cortical development and function. Electrophysiological activity was assessed using MEA recordings and integrated with multiomic profiling, including scRNA-seq, proteomics, glycoproteomics, N-glycan imaging, lipidomics, and metabolomics. X-inactivation status was evaluated in both iPSCs and hCOs. Results: ALG13-CDG hCOs showed reduced glycosylation of proteins involved in ECM organization, neuronal migration, lipid metabolism, calcium homeostasis, and neuronal excitability. These pathway disruptions were supported by proteomic and scRNA-seq data and included altered intercellular communication. Trajectory analyses revealed mistimed neuronal maturation with early inhibitory and delayed excitatory development, indicating an E/I imbalance. MEA recordings demonstrated early network hypoactivity with reduced firing rates, immature burst structure, and shortened axonal projections, while transcriptomic and proteomic signatures suggested emerging hyperexcitability. Altered lipid and GlcNAc metabolism, along with skewed X-inactivation, were also observed. Conclusions: Our study reveals that ALG13-CDG is a disorder of brain-specific hypoglycosylation that disrupts key neurodevelopmental pathways and destabilizes cortical network function. Through integrated multiomic and functional analyses, we identify early network hypoactivity, mistimed neuronal maturation, and evolving E/I imbalance that progresses to compensatory hyperexcitability, providing a mechanistic basis for seizure vulnerability. These findings redefine ALG13-CDG as disorders of cortical network instability, offering a new framework for targeted therapeutic intervention. Full article

Preeclampsia (PE) is the onset of hypertension in pregnancy with systemic involvement; PE poses significant risks of cerebral complications, including eclampsia and long-term cognitive impairment. This review explores the potential of neurological biomarkers—neurofilament light chain (NfL), neuron-specific enolase (NSE), S100 Calcium Binding Protein B (S100B), and tau—as indicators of cerebral injury in PE. A literature search identified studies comparing biomarker levels in preeclamptic and healthy pregnancies. Findings reveal elevated plasma levels of NfL, NSE, S100B, and Tau in PE, with NfL showing the strongest association with blood–brain barrier dysfunction, cognitive symptoms, and disease severity. Variations between plasma and cerebrospinal fluid levels suggest impaired BBB integrity rather than increased central nervous system production. Despite promising correlations, limitations include small sample sizes, lack of standardized thresholds, and limited CSF data. While NfL emerges as a particularly promising marker for risk stratification, further research is needed to validate the clinical utility of these biomarkers in routine PE management. Full article

Monogenic diabetes (MD) is a rare and heterogeneous group of disorders caused by genetic variants in genes involved in glucose metabolism. Among many MD genes, the insulin gene (INS) deserves special attention, as its variants are responsible for both permanent neonatal diabetes mellitus (PNDM) and transient neonatal diabetes mellitus (TNDM), as well as a form of MODY (maturity-onset diabetes of the young)—INS-MODY. The aim of the study was to perform a clinical and molecular analysis of patients focused on the evaluation of INS gene variants identified during molecular testing in patients referred with suspected MD, and to assess the prediction of their impact on protein structure using in silico methods. Between 2017 and 2024, 1043 unrelated probands were tested using targeted next-generation sequencing (tNGS) panels. Three pathogenic or likely pathogenic variants in the INS gene were identified in three unrelated families, indicating that this gene accounts for 0.38% of MD cases. This allowed for the diagnosis of PNDM in two patients with diabetes diagnosed within the first four months of life and INS-MODY in a patient with diabetes since the age of 16. Moreover, in the patient with PNDM and the INS:c.T104C variant, additional disorders were identified in the form of intrauterine growth restriction (IUGR) and neurological disorders. Importantly, two of the identified genetic variants, c.C103G and c.G3C, have not previously been described in the literature. Furthermore, in silico analysis of the variants at the protein level, i.e., investigation of mutations at the 35th residue, indicated that symptom severity correlates with the extent of structural changes in insulin. The results obtained broaden the spectrum of causative variants of the INS gene, but also emphasize the clinical significance of these variants in patients with various forms of diabetes, pointing to the key role of comprehensive genetic testing in enabling accurate diagnosis and targeted treatment of patients. Full article

Influenza-associated encephalitis/encephalopathy (IAE) is a severe neurological complication characterized by central nervous system dysfunction and structural damage following influenza virus infection. Predominantly affecting infants and young children, IAE exhibits its highest incidence in those under five years of age. Key clinical manifestations of IAE include acute seizures, sudden high fever, and impaired consciousness, frequently progressing to coma. Neuroimaging, particularly magnetic resonance imaging (MRI), often reveals multifocal brain lesions involving multiple brain regions, including the cerebellum, brainstem, and corpus callosum. The prognosis of IAE is poor, with a mortality rate reaching 30%. Current diagnosis relies heavily on clinical presentation and characteristic neuroimaging findings, as the precise pathogenesis of IAE remains elusive. While various research models, including cell lines, brain organoids, and animal models, have been developed to recapitulate IAE features, significant limitations persist in modeling the core clinical pathophysiology observed in pediatric patients, necessitating further model refinement. This review synthesizes the clinical spectrum of IAE, summarizes progress in understanding its pathogenesis, and critically evaluates existing research models. We aim to provide a foundation for utilizing experimental approaches to elucidate IAE mechanisms and identify potential therapeutic strategies. Full article

Background/Objectives: This study aimed to characterize objective sleep measures in subacute acquired brain injury (ABI) and examine if disturbed sleep is associated with poor recovery outcomes. Another objective was to compare the functional connectivity of the brain between ABI poor sleepers and ABI normal sleepers as measured by resting state functional magnetic resonance imaging (rs-fMRI). Methods: This was a pilot, prospective, observational study of ABI subjects compared with age and gender-matched healthy controls. A total of 27 ABI subjects (consisting of ischemic or haemorrhagic stroke, or traumatic injury) were recruited from the outpatient clinics of a tertiary hospital with a neurological centre, and 49 healthy controls were recruited by word-of-mouth referrals. Study procedure involved subjective and objective sleep measures, self-report psychological measures, cognitive tests, and structural and functional MRI of the brain. Results: The frequency of poor-quality sleep was 66.67% in the ABI group and not significantly different from 67.35% in the control group when compared by chi-squared test (p = 0.68). ABI subjects with poor sleep had worse performance on a test of sustained attention (Colour Trails Test 1) than healthy controls with poor sleep when compared by Student’s t-test (mean 55.95 s, SD ± 18.48 vs. mean 40.04 s, SD ± 14.31, p = 0.01). Anxious ABI subjects have poorer sleep efficiency and greater time spent awake after sleep onset (WASO). ABI-poor sleepers show significantly greater functional connectivity within a frontoparietal network and bilateral cerebellum. Conclusions: Sleep problems after ABI are associated with poorer cognitive and psychological outcomes. ABI-poor sleepers exhibit altered functional connectivity within regions that contribute to motor planning, attention, and self-referential processes, suggesting that disrupted sleep after ABI may impair the integration of sensorimotor and cognitive control systems, and therefore, impair recovery. Full article

A total of 250 known and novel compounds—ketamine and serotonergic psychedelics or their analogues—designed to target depression, addictions and/or other mental or neurological disorders and developed as “recreational” (illegal) drugs from three chemical families, ergolines, tryptamines and phenylethylamines, were investigated in the context of their ability to cross the human placenta. Using a novel multivariate model involving compounds’ drug-likeness (according to Lipinski’s Ro5), caco-2 membrane permeability, fraction unbound to plasma proteins, steady-state volume of distribution and the total count of heteroatoms (non-carbon atoms with hydrogens included), it was established that the majority of studied compounds are likely to cross the placenta easily, most probably by the passive diffusion mechanism. Atomic contributions of structural elements of studied compounds were investigated using the Morgan fingerprinting algorithm and it was postulated that the fragments promoting transport of compounds across the placenta are carbonyl, hydroxyl, nitro- and phosphoryloxy groups—rigid polycyclic structures, bulky alkyl/aryl groups and halogen atoms restrict the trans-placental passage. All studied compounds are expected to be relatively easily obtained by synthetic routes, which makes them an interesting target for manufacturers of illegal drugs and warrants the need to pursue pharmacological studies of these compounds in silico. Full article

Background and Clinical Significance: Histiocytosis encompasses Langerhans cell histiocytosis (LCH) and non-LCH, such as Erdheim–Chester disease (ECD). ECD or a mixed type of histiocytosis (LCH/ECD) may initially involve the central nervous system (CNS), resulting in a delayed diagnosis. More recently, dabrafenib and trametinib (Dab/Tra regimen) have become available in its treatment. Case Presentation: A 46-year-old woman with CNS involvement of mixed histiocytosis (BRAF V600E-positive LCH/ECD) was treated with combination therapy using a Dab/Tra regimen. At initial presentation, she exhibited central diabetes insipidus, dysarthria, and gait disturbance with mild spasticity and ataxia, requiring walking assistance even for short distances. The interval from the onset of central neurological symptoms to diagnosis of mixed histiocytosis was 4 years. The introduction of targeted therapy was 2 years later. After seven months of Dab/Tra therapy, partial neurological improvement was observed, as reflected by a decrease in the SARA score from 21/40 to 13/40 and the ICARS score from 33/100 to 28/100. However, further neurological recovery remained significantly delayed. Conclusions: We suspect that the limited improvement may be attributable to the delayed initiation of targeted therapy, in contrast to the more rapid and pronounced responses reported in cases where treatment was started earlier. Full article

Background and Clinical Significance: Deficiency of Adenosine Deaminase 2 (DADA2) is a rare monogenic vasculopathy characterised by systemic inflammatory and immunodeficiency features. Although neurological and haematological manifestations are well-documented, hepatic vascular involvement remains underappreciated. This report aims to describe the clinical and imaging characteristics of hepatic vascular involvement in a patient with DADA2 and to illustrate the evolution of hepatic lesions during long-term Etanercept therapy. In addition, we provide a synthesis of the available evidence on hepatic manifestations in DADA2, emphasising vascular pathology, clinical presentation, and therapeutic implications. Case Presentation: We describe a girl with early-onset DADA2 presenting with recurrent systemic inflammation, hypogammaglobulinaemia, vasculopathy, and two childhood strokes, followed by the development of multiple FNH-like hepatic nodules on CEUS and MRI with persistently elevated GGT. Genetic testing confirmed biallelic ADA2 mutations, and treatment with Etanercept led to sustained clinical stabilisation and marked regression of liver lesions over a nine-year follow-up period. Her older sister, carrying the same mutations, showed a milder phenotype without hepatic involvement but experienced a mesenteric vascular event. Conclusions: Large regenerative nodules with an FNH-like appearance on CEUS or MRI have not been previously reported in this setting. In our patient, Etanercept therapy produced a favourable hepatic response, reflected by a significant reduction in both the number and size of the lesions. Our case contributes to the understanding of liver disease in DADA2 and the influence of imaging and treatment on the hepatic manifestations of the condition. Full article

Neurodevelopmental disorders (NDDs) with ataxia are genetically heterogeneous and remain a diagnostic challenge. Recent advances in genomic technologies have facilitated the identification of rare, potentially causative variants in genes not traditionally associated with classic NDD phenotypes. The DNAH14 gene, encoding a dynein axonemal heavy chain involved in ciliary motility, has recently emerged as a novel candidate in neurological syndromes. Here, we report two Turkish siblings presenting with late-onset balance disorder, progressive ataxia, and cognitive impairment. Initial genetic analysis revealed that both siblings also harbor FXN GAA repeat expansions consistent with pathogenic Friedreich’s ataxia (FRDA). To elucidate the molecular basis of the patients’ cognitive impairment, whole-exome sequencing was performed. This analysis identified a novel homozygous frameshift variant in the DNAH14 gene, located within the conserved linker domain upstream of the motor core, which is critical for ATP hydrolysis and microtubule interactions. The variant is absent from population databases, predicted to be deleterious by multiple in silico algorithms, and segregates in the family in a manner consistent with autosomal recessive inheritance. The coexistence of FRDA expansions and a truncating DNAH14 variant suggests a potential dual genetic contribution to the observed phenotype, in which FRDA-associated pathology likely underlies the ataxia, while DNAH14 disruption may contribute to additional neurodevelopmental features. This is the first report describing the co-occurrence of FRDA and a homozygous truncating DNAH14 variant in the same individuals, broadening our understanding of overlapping neurogenetic mechanisms. Our findings expand the phenotypic spectrum of DNAH14-related disorders and highlight the importance of considering multilocus pathogenic variants in patients with complex or atypical ataxia presentations. Full article

Background and Clinical Significance: Patients with Hodgkin lymphoma (HL) often present with lymphadenopathy, biochemical inflammation, and constitutional symptoms, but may experience symptoms from extra-nodal organs. Symptoms are caused by either lymphoma or a paraneoplastic phenomenon but overt central nervous system (CNS) involvement in HL is very uncommon. However, in rare cases, paraneoplastic neuro-ophthalmologic manifestations occur. Case Presentation: This case report describes a young female diagnosed with HL initially presenting with visual loss, reduced visual field, impaired balance, and sensory disturbances but no evidence of CNS-lymphoma. After treatment with bleomycin, etoposide, adriamycin, cyclophosphamide, vincristine, procarbazine, and prednisolone (escalated BEACOPP), she experienced full recovery of all neurological and ophthalmological symptoms. She experienced complete remission without any signs of relapse at follow-up after 2.5 years. Paraneoplastic cerebellar degeneration (PCD) related to HL have been described as a rare neurological syndrome, with varying neurological symptoms preceding the diagnosis of HL. PCD is typically associated with anti-Tr antibodies. Despite being negative for anti-Tr antibodies in both serum and cerebrospinal fluid (CSF), the neuro-ophthalmologic symptoms were interpreted as a paraneoplastic phenomenon in HL resembling PCD. The exact pathophysiology in this case is unknown but might be associated with undetected antigens and T-cell-mediated autoimmunity because of the presence of non-malignant T-cells in the CSF. Conclusions: This manuscript describes a case of an atypical presentation of HL with neuro-ophthalmologic symptoms which fully recovered upon anti-lymphoma treatment. Because of the good prognosis, we aim to emphasize the awareness of rare cases of HL initially presenting such manifestations to avoid diagnostic delays. Full article

Background/Objectives: Edwardsiella tarda is a rare Gram-negative pathogen that uncommonly infects humans. Neonatal infections are extremely rare but often severe, with a high incidence of central nervous system (CNS) complications. Case presentation: We report a term neonate born via spontaneous vaginal delivery who developed systemic signs of infection within 18 h of life. Blood and cerebrospinal fluid (CSF) cultures grew Edwardsiella tarda. CSF analysis revealed severe meningoencephalitis. Maternal stool culture was also positive for E. tarda, suggesting vertical transmission. Despite initial systemic antibiotic therapy with ampicillin, gentamicin, and ceftriaxone, neuroimaging revealed progressive multifocal brain abscesses. The infant underwent a series of neurosurgical procedures, including bilateral drainage of abscesses, Rickham reservoir placement and ventriculoperitoneal shunting. A revised antibiotic regimen, including systemic meropenem and trimethoprim-sulfamethoxazole plus intrathecal gentamicin, was administered. At six months, the infant showed mild motor delay with lower limb hypertonia and was under close neurosurgical and developmental follow-up. Methods: We conducted a literature review of 12 published neonatal E. tarda infections, including our case. Results: Most infected infants presented within 72 h of life and exhibited CNS involvement. Mortality was 25%, and 44% of survivors experienced long-term neurologic sequelae. Conclusions: Edwardsiella tarda infection in neonates is rare but potentially devastating. Early suspicion, culture confirmation, aggressive antibiotic therapy, and multidisciplinary care, including neurosurgical management, are essential for improving outcomes. Full article

Background: Metabolic acidosis is a frequent and serious complication in critically ill neonates, particularly preterm infants, and is associated with an increased risk of mortality, intraventricular hemorrhage, and long-term neurodevelopmental impairment. Despite limited evidence, sodium bicarbonate (SB) is widely administered in neonatal intensive care units (NICUs) to correct acidosis, largely extrapolated from adult and pediatric practice. However, concerns have been raised about its potential adverse effects, including paradoxical intracellular acidosis, impaired cerebral autoregulation, and increased risk of neurological injury. Given the uncertainty regarding both its efficacy and safety, we conducted a systematic review and meta-analysis to evaluate the role of SB administration in the neonatal population. Methods: MEDLINE, Scopus, and the Cochrane Library were searched using specific medical subject headings and terms. We included all study published up to July 2025 that involved newborns treated with SB. The primary outcome was positive response to treatment, while secondary outcomes included mortality, morbidity, and long-term impairment. Results: We analyzed 10 studies (9 randomized and 1 unrandomized study, including 660 neonates). Pooled results from the randomized controlled studies showed no efficacy of SB in newborns. Data from one unrandomized study showed an increased risk for mortality (OR 13.1 p = 0.02), clinical seizures (OR 2.8, p = 0.01), and a combined outcome of death or neurological damage (OR 3.1 p < 0.01) for neonates treated with SB. Conclusions: Current evidence is insufficient to support the routine administration of SB in NICUs. Neonatologists have the responsibility to administer only drugs of proven efficacy, personalizing therapy on the basis of a pathology’s etiology, in order to reduce risk and optimize benefits. In the absence of robust, statistically significant data, the indiscriminate use of SB should be discouraged in current clinical practice. PROSPERO registration number: CRD420251132502. Full article

Background and Clinical Significance: Wartenberg’s syndrome (cheiralgia paresthetica) is classically described as a pure sensory neuropathy of the superficial branch of the radial nerve (SBRN). However, in rare circumstances, dynamic mechanical irritation around the radial styloid may produce an atypical clinical phenotype with concurrent motor impairment, broadening the clinical significance of recognizing motion-related compression mechanisms. Case Presentation: A 35-year-old woman presented with persistent dorsoradial wrist pain and numbness, accompanied by progressive weakness of thumb extension, five years after a conservatively treated nondisplaced scaphoid fracture. Neurological examination demonstrated sensory loss in the SBRN distribution and Medical Research Council (MRC) grade 3/5 strength of the extensor pollicis longus (EPL). Nerve conduction studies revealed a markedly prolonged EPL motor latency (4.5 ms; normal ≤ 2.5 ms) with preserved sensory conduction. High-resolution ultrasound showed focal enlargement of the SBRN (cross-sectional area 0.13 cm²) and, critically, dynamic snapping of the nerve over the radial styloid that reproduced the patient’s symptoms. The patient underwent ten weekly sessions of ultrasound-guided hydrodissection with 5% dextrose. After treatment, the pain Visual Analog Scale improved from 8/10 to 0/10 and EPL strength recovered to MRC 5/5. Follow-up nerve conduction studies demonstrated normalization of EPL motor latency (2.1 ms), and repeat ultrasound confirmed resolution of SBRN enlargement and snapping. Conclusions: This case expands the phenotype of Wartenberg’s syndrome to include mixed sensory–motor involvement associated with dynamic SBRN snapping at the radial styloid. Dynamic ultrasound was pivotal for identifying the motion-dependent mechanism, and ultrasound-guided 5% dextrose hydrodissection achieved complete sensory and motor recovery as a minimally invasive and effective treatment option. Full article