Lateral semi-circular canal asymmetry in females with idiopathic scoliosis

Clinical features and pathogenesis of scoliosis due to spinal astrocytoma

The aetiology of scoliosis remains unclear. Some studies have focused on the theory of possible muscular imbalance. The role of the spinal cord, which directly innervates the paraspinal muscles, in muscular imbalance has not yet been studied. Spinal astrocytomas often grow on one side of the spinal cord, destroying it asymmetrically. Asymmetrical damage to the spinal cord can lead to asymmetrical changes in paraspinal muscles. The present study investigated the effect of muscular imbalance on scoliosis by observing scoliosis caused by spinal astrocytomas. Patients diagnosed with spinal astrocytomas in a single centre were analysed, and the type and side of the symptoms, sagittal tumour position, scoliosis, end vertebrae and apical vertebrae of scoliosis were recorded. The tumour side was assumed from symptom type and side, and the cross-sectional area of the paraspinal muscles on both sides of the end vertebra was outlined and compared. The incidence of astrocytoma-induced scoliosis was significantly higher in patients with unilateral symptoms. The inferred tumour side was highly consistent with the convex side of scoliosis. The distal vertebral segments of scoliosis were consistent with the spinal cord segments involved in the astrocytomas. The apical vertebrae were more caudal in astrocytoma-induced scoliosis. The cross-sectional area of the multifidus muscle on the convex side of apical-level scoliosis was significantly smaller than that on the concave side. However, no significant differences were observed in the erector spinae muscles. Overall, spinal astrocytomas can cause asymmetric destruction of the corresponding spinal cord segment, resulting in asymmetric atrophy and weakness of the multifidus muscle innervated by the spinal cord segment, thereby causing scoliosis that is convex to the weaker side. This mechanism involves asymmetric lower neuron paralysis of the multifidus muscle. This is a type of scoliosis with several differences from idiopathic scoliosis.

Rare Coding Variants in Patients with Non-Syndromic Vestibular Dysfunction

Vertigo due to vestibular dysfunction is rare in children. The elucidation of its etiology will improve clinical management and the quality of life of patients. Genes for vestibular dysfunction were previously identified in patients with both hearing loss and vertigo. This study aimed to identify rare, coding variants in children with peripheral vertigo but no hearing loss, and in patients with potentially overlapping phenotypes, namely, Meniere's disease or idiopathic scoliosis. Rare variants were selected from the exome sequence data of 5 American children with vertigo, 226 Spanish patients with Meniere's disease, and 38 European-American probands with scoliosis. In children with vertigo, 17 variants were found in 15 genes involved in migraine, musculoskeletal phenotypes, and vestibular development. Three genes, OTOP1, HMX3, and LAMA2, have knockout mouse models for vestibular dysfunction. Moreover, HMX3 and LAMA2 were expressed in human vestibular tissues. Rare variants within ECM1, OTOP1, and OTOP2 were each identified in three adult patients with Meniere's disease. Additionally, an OTOP1 variant was identified in 11 adolescents with lateral semicircular canal asymmetry, 10 of whom have scoliosis. We hypothesize that peripheral vestibular dysfunction in children may be due to multiple rare variants within genes that are involved in the inner ear structure, migraine, and musculoskeletal disease.

Neurological mechanisms involved in idiopathic scoliosis. Systematic review of the literature

The literature that explains the neurological mechanisms underlying the development or compensation of idiopathic scoliosis is limited. The objective of the article is to describe and integrate the mechanisms and nerve pathways through which idiopathic scoliosis is compensated and/or developed. A narrative systematic review in different databases of the studies published between January 1, 1967 and April 1, 2021 was performed, using the following terms: "scoliosis", "vision", "eye", "vestibule", "labyrinth" "posture", "balance", "eye movements", "cerebellum", "proprioception", and "physiological adaptation". In the search, 1112 references were identified, of which 50 were finally included: 46 observational analytical clinical studies-descriptive (between cohorts, report and series of cases) and 4 experimental studies. In the neurological response to idiopathic scoliosis, the sensory-cortical integration of the afferences in the visual-oculomotor-vestibular-proprioceptive systems, allows modifications at the postural level in order to achieve an initial compensation on the sagittal balance and the centre of body mass; however, over time these compensation mechanisms may be exhausted causing progression of the initial deformity.

Vestibular Morphological Alterations in Adolescent Idiopathic Scoliosis: A Systematic Review of Observational Studies

Adolescent idiopathic scoliosis (AIS) is the most frequent pediatric spinal deformity. Its treatment still shows limited results due to the existent lack of knowledge regarding etiopathogenesis. Thus, the purpose of the study is to check the existence of vestibular morphological alterations among idiopathic scoliosis patients. To meet the objective, we performed this systematic review searching studies in PubMed Medline, SCOPUS, Web of Science, CINAHL Complete and SciELO until 15 September 2022. Articles that analyzed the morphology of the vestibular apparatus were selected, comparing subjects with AIS versus healthy subjects. Variables were selected that measured the orientation of the channels as well as the general conformation of the vestibular apparatus. One hundred and eighty-five records were retrieved in the preliminary searches, of which five studies were finally included, providing data from 154 participants (83 cases and 71 healthy controls) with a mean age 16.07 ± 2.48 years old. Two studies conclude that the superior and lateral semicircular canals are longer and thinner in patients with AIS. One study concluded that the measure between centers of superior and lateral canals and the angle whose vertex is placed the center of posterior canal were significantly shorter in subjects with AIS than in healthy controls in the left-side of vestibular apparatus. Two studies found an asymmetry in the verticality of the lateral canals on both sides in subjects with AIS, although it is not clear whether the left canal is in a more horizontal or vertical position. Patients with AIS seem to present morphological asymmetries of the vestibular apparatus, fundamentally on the left side. These anomalies seem to correlate with the location of the curve but not with its laterality or severity.

Vestibular Morphological Asymmetry Associated With Motion Sickness Susceptibility

Sensory conflicts leading to motion sickness can occur not only between but also within sensory modalities. The vestibular organs are located in both left and right inner ears, and their misalignment can be a source of self-motion related sensory conflicts. In the current study, using inner ear magnetic resonance imaging, we examined whether morphological asymmetry of the bilateral vestibular organs was associated with motion sickness susceptibility. The results showed a larger position asymmetry of bilateral vestibular organs in individuals with high rather than low susceptibility. In addition, vestibular position asymmetry was associated with reciprocal interaction (negative resting state functional connectivity) between vestibular and visuocortical regions in lowly, but not highly, susceptible individuals. In conclusion, these findings suggest that vestibular morphological asymmetry can be a source of sensory conflicts in individuals with dysfunctional reciprocal visuo-vestibular interactions, a putative neural mechanism for resolving sensory conflicts.

Severity of Idiopathic Scoliosis Is Associated with Differential Methylation: An Epigenome-Wide Association Study of Monozygotic Twins with Idiopathic Scoliosis

Epigenetic mechanisms may contribute to idiopathic scoliosis (IS). We identified 8 monozygotic twin pairs with IS, 6 discordant (Cobb angle difference > 10°) and 2 concordant (Cobb angle difference ≤ 2°). Genome-wide methylation in blood was measured with the Infinium HumanMethylation EPIC Beadchip. We tested for differences in methylation and methylation variability between discordant twins and tested the association between methylation and curve severity in all twins. Differentially methylated region (DMR) analyses identified gene promoter regions. Methylation at cg12959265 (chr. 7 DPY19L1) was less variable in cases (false discovery rate (FDR) = 0.0791). We identified four probes (false discovery rate, FDR < 0.10); cg02477677 (chr. 17, RARA gene), cg12922161 (chr. 2 LOC150622 gene), cg08826461 (chr. 2), and cg16382077 (chr. 7) associated with curve severity. We identified 57 DMRs where hyper- or hypo-methylation was consistent across the region and 28 DMRs with a consistent association with curve severity. Among DMRs, 21 were correlated with bone methylation. Prioritization of regions based on methylation concordance in bone identified promoter regions for WNT10A (WNT signaling), NPY (regulator of bone and energy homeostasis), and others predicted to be relevant for bone formation/remodeling. These regions may aid in understanding the complex interplay between genetics, environment, and IS.

Whole Exome Sequencing of 23 Multigeneration Idiopathic Scoliosis Families Reveals Enrichments in Cytoskeletal Variants, Suggests Highly Polygenic Disease

Adolescent idiopathic scoliosis (AIS) is a lateral spinal curvature >10° with rotation that affects 2–3% of healthy children across populations. AIS is known to have a significant genetic component, and despite a handful of risk loci identified in unrelated individuals by GWAS and next-generation sequencing methods, the underlying etiology of the condition remains largely unknown. In this study, we performed exome sequencing of affected individuals within 23 multigenerational families, with the hypothesis that the occurrence of rare, low frequency, disease-causing variants will co-occur in distantly related, affected individuals. Bioinformatic filtering of uncommon, potentially damaging variants shared by all sequenced family members revealed 1448 variants in 1160 genes across the 23 families, with 132 genes shared by two or more families. Ten genes were shared by >4 families, and no genes were shared by all. Gene enrichment analysis showed an enrichment of variants in cytoskeletal and extracellular matrix related processes. These data support a model that AIS is a highly polygenic disease, with few variant-containing genes shared between affected individuals across different family lineages. This work presents a novel resource for further exploration in familial AIS genetic research.

Etiopathogenesis of adolescent idiopathic scoliosis: Review of the literature and new epigenetic hypothesis on altered neural crest cells migration in early embryogenesis as the key event

Adolescent idiopathic scoliosis (AIS) affects 2-3% of children. Numerous hypotheses on etiologic/causal factors of AIS were investigated, but all failed to identify therapeutic targets and hence failed to offer a cure. Therefore, currently there are only two options to minimize morbidity of the patients suffering AIS: bracing and spinal surgery. From the beginning of 1960th, spinal surgery, both fusion and rod placement, became the standard of management for progressive adolescent idiopathic spine deformity. However, spinal surgery is often associated with complications. These circumstances motivate AIS scientific community to continue the search for new etiologic and causal factors of AIS. While the role of the genetic factors in AIS pathogenesis was investigated intensively and universally recognized, these studies failed to nominate mutation of a particular gene or genes combination responsible for AIS development. More recently epigenetic factors were suggested to play causal role in AIS pathogenesis. Sharing this new approach, we investigated scoliotic vertebral growth plates removed during vertebral fusion (anterior surgery) for AIS correction. In recent publications we showed that cells from the convex side of human scoliotic deformities undergo normal chondrogenic/osteogenic differentiation, while cells from the concave side acquire a neuronal phenotype. Based on these facts we hypothesized that altered neural crest cell migration in early embryogenesis can be the etiological factor of AIS. In particular, we suggested that neural crest cells failed to migrate through the anterior half of somites and became deposited in sclerotome, which in turn produced chondrogenic/osteogenic-insufficient vertebral growth plates. To test this hypothesis we conducted experiments on chicken embryos with arrest neural crest cell migration by inhibiting expression of Paired-box 3 (Pax3) gene, a known enhancer and promoter of neural crest cells migration and differentiation. The results showed that chicken embryos treated with Pax3 siRNA (microinjection into the neural tube, 44 h post-fertilization) progressively developed scoliotic deformity during maturation. Therefore, this analysis suggests that although adolescent idiopathic scoliosis manifests in children around puberty, the real onset of the disease is of epigenetic nature and takes place in early embryogenesis and involves altered neural crest cells migration. If these results confirmed and further elaborated, the hypothesis may shed new light on the etiology and pathogenesis of AIS.

Butterfly Effect in Chaotic Image Segmentation

The exploitation of the important features exhibited by the complex systems found in the surrounding natural and artificial space will improve computational model performance. Therefore, the purpose of the current paper is to use cellular automata as a tool simulating complexity, able to bring forth an interesting global behaviour based only on simple, local interactions. We show that, in the context of image segmentation, a butterfly effect arises when we perturb the neighbourhood system of a cellular automaton. Specifically, we enhance a classical GrowCut cellular automaton with chaotic features, which are also able to improve its performance (e.g., a Dice coefficient of 71% in case of 2D images). This enhanced GrowCut flavor (referred to as Band-Based GrowCut) uses an extended, stochastic neighbourhood, in which randomly-selected remote neighbours reinforce the standard local ones. We demonstrate the presence of the butterfly effect and an increase in segmentation performance by numerical experiments performed on synthetic and natural images. Thus, our results suggest that, by having small changes in the initial conditions of the performed task, we can induce major changes in the final outcome of the segmentation.