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Electrophysiological and histological changes of paraspinal muscles in adolescent idiopathic scoliosis

  • Charles University in Prague, Third School of Medicine
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Purpose The pathogenesis of adolescent idiopathic scoliosis (AIS) remains poorly understood. To date, potentially involved local changes in the deep paraspinal muscles still remain unknown. Methods Needle electromyography (EMG) and muscle biopsy of paraspinal muscles at convexity and concavity of the AIS main thoracic curve were performed in 25 subjects. In this group, EMG was performed in 16 AIS subjects (12 females, 12–27 years), muscle biopsy in 18 AIS subjects (15 females, 11–31 years) compared to 10 non-scoliotic controls (6 females, 12–55 years). Samples of muscle tissue were removed during corrective surgery and were examined histologically, enzyme histochemically and immunohistochemically. Both methods of EMG and muscle biopsy were performed in 9 subjects (7 women, 12–27 years). Results Right curve convexity was found in 24 AIS subjects. Amplitudes of motor unit action potentials (MUPs) were significantly increased on the AIS curve convexity versus concavity. Turns, duration and phases of MUPs were without any significant changes. In all 18 subjects, the histological examination revealed muscle fiber redistribution with numerical predominance of type I on the curve convexity which strongly correlated with the progression of the Cobb angle. Conclusion Our findings demonstrate significant changes of muscle fiber redistribution in the paraspinal muscles of AIS with increased proportion of type I on the convexity corresponding to a significantly higher amplitude of MUPs on the same side. A possible explanation of this alteration is a secondary adaptation due to chronic high load demand.
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Electrophysiological and histological changes of paraspinal
muscles in adolescent idiopathic scoliosis
I. Stetkarova
J. Zamecnik
V. Bocek
P. Vasko
K. Brabec
M. Krbec
Received: 2 December 2015 / Revised: 23 May 2016 / Accepted: 24 May 2016 / Published online: 31 May 2016
ÓSpringer-Verlag Berlin Heidelberg 2016
Purpose The pathogenesis of adolescent idiopathic scol-
iosis (AIS) remains poorly understood. To date, potentially
involved local changes in the deep paraspinal muscles still
remain unknown.
Methods Needle electromyography (EMG) and muscle
biopsy of paraspinal muscles at convexity and concavity of
the AIS main thoracic curve were performed in 25 subjects.
In this group, EMG was performed in 16 AIS subjects (12
females, 12–27 years), muscle biopsy in 18 AIS subjects
(15 females, 11–31 years) compared to 10 non-scoliotic
controls (6 females, 12–55 years). Samples of muscle tis-
sue were removed during corrective surgery and were
examined histologically, enzyme histochemically and
immunohistochemically. Both methods of EMG and mus-
cle biopsy were performed in 9 subjects (7 women,
12–27 years).
Results Right curve convexity was found in 24 AIS sub-
jects. Amplitudes of motor unit action potentials (MUPs)
were significantly increased on the AIS curve convexity
versus concavity. Turns, duration and phases of MUPs
were without any significant changes. In all 18 subjects, the
histological examination revealed muscle fiber
redistribution with numerical predominance of type I on
the curve convexity which strongly correlated with the
progression of the Cobb angle.
Conclusion Our findings demonstrate significant changes
of muscle fiber redistribution in the paraspinal muscles of
AIS with increased proportion of type I on the convexity
corresponding to a significantly higher amplitude of MUPs
on the same side. A possible explanation of this alteration
is a secondary adaptation due to chronic high load demand.
Keywords Idiopathic scoliosis Muscle biopsy
Neurophysiology EMG Paraspinal muscles
Adolescent idiopathic scoliosis (AIS) is a disease of
unknown etiopathogenesis. There are many theories based
on different principles and there is no doubt that the eti-
ology is multifactorial [1,2]. Neuroadaptive theory
describes the disparity between the growth rate of the
neural tube and axial skeleton of the spine during growth
development [3]. Some authors believe that the main role is
played by disturbances of oculovestibular proprioception
and sensorimotor disintegration in the central nervous
system [4,5]. Connective tissue abnormality, abnormal
biomechanical forces, neurophysiologic predisposition, or
an increase in calmodulin or decrease in melatonin [6]
during puberty are also discussed in the pathophysiology of
this disorder. Apart from epigenetic modification, envi-
ronmental factors may influence idiopathic scoliosis, too
In AIS, some authors have concentrated on muscle and
peripheral nerve disturbances, but in other studies impair-
ment of the spinal cord and different pattern of brain
&I. Stetkarova
Department of Neurology, Third Faculty of Medicine,
Charles University in Prague and Faculty Hospital Kralovske
Vinohrady, Ruska 87, 100 00 Prague 10, Czech Republic
Department of Pathology and Molecular Medicine, 2nd
Faculty of Medicine, Charles University in Prague and Motol
University Hospital, Prague, Czech Republic
Department of Orthopedics and Traumatology, 3rd Faculty of
Medicine, Charles University in Prague and Faculty Hospital
´Vinohrady, Prague, Czech Republic
Eur Spine J (2016) 25:3146–3153
DOI 10.1007/s00586-016-4628-8
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... They found a significant difference in the muscle activation patterns between the two types of physiotherapy exercises. Stetkarova et al. [24] used needle EMG instead of surface EMG (sEMG) to investigate the changes in the paraspinal muscles of AIS patients, and found higher amplitudes of the motor unit potentials on the convex side of the scoliosis curve. They also conducted a muscle biopsy and found predominantly type I muscle fibers in the curve convexity. ...
... The type I muscle fibers show higher fatigue resistance and lower contractile speed as opposed to the type II muscle fibers [25]. Moreover, it is also found that AIS progresses more rapidly depending on the Cobb angle, which is significantly correlated with the increased proportion of type I fibers on the convex side of the scoliotic curve [24,26]. The changes might cause the asymmetry of muscle activity. ...
... The studies also have limitations. Although many have focused on female participants since a higher percentage of patients with scoliosis are female [22][23][24], nevertheless, the gender bias inhibits the generalizability of the results. In addition, most of these studies have only focused on no more than 12 participants or even as few as 10 participants [19,20,22,24]. ...
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A large number of studies have used electromyography (EMG) to measure the paraspinal muscle activity of adolescents with idiopathic scoliosis. However, investigations on the features of these muscles are very limited even though the information is useful for evaluating the effectiveness of various types of interventions, such as scoliosis-specific exercises. The aim of this cross-sectional study is to investigate the characteristics of participants with imbalanced muscle activity and the relationships among 13 features (physical features and EMG signal value). A total of 106 participants (69% with scoliosis; 78% female; 9–30 years old) are involved in this study. Their basic profile information is obtained, and the surface EMG signals of the upper trapezius, latissimus dorsi, and erector spinae (thoracic and erector spinae) lumbar muscles are tested in the static (sitting) and dynamic (prone extension position) conditions. Then, two machine learning approaches and an importance analysis are used. About 30% of the participants in this study find that balancing their paraspinal muscle activity during sitting is challenging. The most interesting finding is that the dynamic asymmetry of the erector spinae (lumbar) group of muscles is an important (third in importance) predictor of scoliosis aside from the angle of trunk rotation and height of the subject.
... (S-EMG). Studies have reported that S-EMG activity was found to be higher on the convex side of the scoliotic curve; these findings suggest an overactivation of the paraspinal muscles as a cause of AIS [4][5][6][7] . Conversely, de Oliveira et al. reported that there was no significant difference in electromyographic amplitude of erector spinae on the convex and concave sides 8 . ...
... Conversely, de Oliveira et al. reported that there was no significant difference in electromyographic amplitude of erector spinae on the convex and concave sides 8 . These conflicting results might be due to methodological differences, based on patient selection, arbitrary focus on specific curve types or lack of controlling mechanisms to exclude inadequate posture 7,[9][10][11] . Since these studies describe conflicting results, our research attempted disaggregate analysis of the relationship between paraspinal muscle asymmetry and scoliosis curve types, considering how the curve classifications and recording levels were not accurately described in previous studies. ...
... In some studies, the authors showed that the paraspinalis muscles on the concave side have higher EMG activity, while others could not find asymmetrical activity in the paraspinalis muscles of scoliosis patients 8,9,11 . However, recent literature has reported dominance of EMG activity on the convex side of the scoliotic curve [4][5][6][7] . In this study, we measured S-EMG in a specific posture (superman position) to induce proper submaximal contraction of the paraspinalis muscles. ...
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Abstract There have been many studies on adolescent idiopathic scoliosis related abnormal muscle contractions of the spine. However, previous studies using surface electromyography to investigate paraspinal muscle asymmetry are controversial, lacking in clarity of results, and hindered by methodological limitations. The purpose of this study was to investigate the relationship between imbalance factors including surface electromyography activity according to the scoliosis curve type and leg length discrepancy and adolescent idiopathic scoliosis curve types. Seventy-nine patients with scoliosis were prospectively enrolled and were divided into five types: single thoracic, thoracolumbar, lumbar, double thoracic, and double major. Cobb angle and structural variables were measured. Surface electromyography examinations were conducted at the 7th, 12th thoracic erector spinae, 3rd lumbar erector spinae, and multifidus muscles during the superman position keeping prone spinal extension to lift the arms and legs off the floor. Whole spine radiographs were obtained to measure the Cobb angle, coronal imbalance, pelvic height and angle, and femoral head height. In the double major, thoracolumbar, and lumbar types, the mean root mean squared (RMS) EMG amplitudes were significantly higher on the convex side than the concave side (P
... Taken together, the intercellular cell communications and comparisons in GO and pathway analysis indicated that MSCs of AIS were remodeled to downregulate their osteoblast differentiation through immunocytes recruitment and interaction. Although there was a study reporting immune system abnormalities in AIS paraspinal muscle, 42,54 the present study was the first study to report the potential T lymphocyte-mediated pathogenesis, and further research is necessary to verify this hypothesis. ...
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Backgrounds Abnormal vertebral growth and development have been found in adolescent idiopathic scoliosis (AIS) patients, and the proliferation and differentiation of bone development-related cells play important roles in its pathogenesis. However, a comprehensive single-cell-level differentiation roadmap in AIS has not been achieved. Methods The present study compared the single-cell level cellular landscapes of spinal cancellous bone tissues between AIS patients and healthy subjects using high throughput single-cell RNA sequencing (scRNA-seq), which covers multiple cellular lineages including osteoblast, chondrocyte, osteoclast and related immunocytes. We constructed the differentiation trajectories of bone development-related cell lineages through pseudotime analysis, and the intercellular-communication networks between bone development-related cells and immunocytes were further developed. Results A total of 11 distinct cell clusters were identified according to the genome-wide transcriptome profiles. t-Distributed stochastic neighbor embedding (t-SNE) analysis showed that mesenchymal stem cells (MSC) were classified into three subtypes: MSC-LOXL2, MSC-IGFBP5, and MSC-GJA1. Gene ontology (GO) analysis showed that MSC-GJA1 might possess greater osteoblast differentiation potential than the others. MSC-IGFBP5 was the specific MSC subtype observed only in AIS. There were two distinct gene expression clusters: OB-DPT and OB-OLFML2B, and the counts of osteoblasts derived from AIS was significantly less than that of non-AIS subjects. In AIS patients, MSC-IGFBP5 failed to differentiate into osteoblasts and exhibited negative regulation of cell proliferation and enhanced cell death. CPC-PCNA was found to be the specific chondrocyte progenitor cell (CPC) subtype observed only in AIS patients. The cell counts of OC-BIRC3 in AIS were less than those in controls. Pseudotime analysis suggested two possible distinct osteoclast differentiation patterns in AIS and control subjects. Monocytes in AIS mainly differentiated into OC-CRISP3. Conclusions Our single-cell analysis first revealed differences existed in the cellular states between AIS patients and healthy subjects and found the differentiation disruption of specific MSC and CPC clusters in AIS. Cell communication analysis provided the possible pathogenesis of osteoblast and chondrocyte differentiation dysfunction in AIS.
... The posterior paraspinal muscles, including the multifidus and erector spinal muscle, provide dynamic stability to the spinal column [9], and its imbalance has been postulated to contribute to the initiation and/or progression of spinal deformity in AIS [10,11]. Previous studies have reported abnormal and asymmetric muscle phenotypes in concave and convex side paraspinal muscles of AIS patients, including electromyography (EMG) activities, muscle volume, muscle fiber types, and fatty and fibrosis infiltration [12][13][14][15][16]. Additionally, one recent study demonstrated a significantly lower density of activated satellite cells for fiber type I in AIS patients when compared to non-scoliosis controls, and the curve severity appeared to be associated with the density of satellite cells and other histological parameters such as cross-sectional areas of muscle fiber and myonuclear density [17]. ...
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Previous studies have reported abnormal muscle morphology and functions in patients with adolescent idiopathic scoliosis (AIS). To answer whether such abnormalities could be reflected in their circulation and their clinical implication for predicting curve progression to the surgical threshold, this preliminary study explored the presence of baseline muscle-related proteins and their association with curve progression. Plasma samples were collected at the first clinical visit for AIS, with patients divided into non-progressive or progressive groups (N = four and four) according to their Cobb angle in six-year follow-ups, with age- and sex-matched healthy subjects (N = 50). Then, the samples were subjected to isobaric tags for relative and absolute quantitation (iTRAQ) for global comparison of untargeted protein expression. Seventy-one differentially expressed proteins (DEPs) were found elevated in progressive AIS. Functional analysis showed that 18 of these are expressed in muscles and play an essential role in muscle activities. Among the muscle-related DEPs, α-actin had the highest fold change in progressive/non-progressive groups. This preliminary study firstly suggested higher circulating levels of muscle structural proteins in progressive AIS, indicating the likelihood of structural damage at the microscopic level and its association with progression to the surgical threshold. Further studies with larger sample sizes are warranted to validate these novel candidates for early diagnosis and predicting progression.
... There is a hypothesis that dysfunctional paraspinal muscles may contribute the development of the scoliotic curve [2,40]. Additionally, reports have described functional and histological differences in the paraspinal muscles between the convex and the concave sides of the curve in IS patients [41,42]. ...
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Idiopathic scoliosis (IS) is a multifactorial disease with epigenetic modifications. Tissue dependent and differentially methylated regions (T-DMRs) may regulate tissue-specific expression of the estrogen receptor 1 gene (ESR1). This study aimed to analyze methylation levels within T-DMR1 and T-DMR2 and its concatenation with ESR1 expression of IS patients. The study involved 87 tissue samples (deep paravertebral muscles, both on the convex and the concave side of the curve, and from back superficial muscles) from 29 girls who underwent an operation due to IS. Patient subgroups were analyzed according to Cobb angle ≤70° vs. >70°. Methylation was significantly higher in the superficial muscles than in deep paravertebral muscles in half of the T-DMR1 CpGs and all T-DMR2 CpGs. The methylation level correlated with ESR1 expression level on the concave, but not convex, side of the curvature in a majority of the T-DMR2 CpGs. The T-DMR2 methylation level in the deep paravertebral muscles on the curvature’s concave side was significantly lower in patients with a Cobb angle ≤70° in four CpGs. DNA methylation of the T-DMRs is specific to muscle tissue location and may be related to ESR1 expression regulation. Additionally, the difference in T-DMR2 methylation may be associated with IS severity.
Background context Abnormal energy metabolism such as lower body weight and body mass index (BMI) and less fat mass is widely reported in patients with adolescent idiopathic scoliosis (AIS) and has been implicated in deformity development. However, the underlying mechanism is largely unclear. LBX1 is one of the promising AIS predisposing genes validated by multicenter studies. Purpose This study aimed to identify differentially expressed proteins (DEPs) relating to energy metabolism in AIS by using proteomic and metabolic analysis and to explore if the expression of these DEPs is associated with clinical parameters and modulated by LBX1. Study design This is a cross-sectional study using clinical data and biological samples followed by basic study using a cellular model. Patient sample Plasma samples were collected from Chinese girls with non-progressive and progressive AIS (N = 7 and 8, respectively) and age-matched healthy girls (N = 50). Paraspinal muscle tissues were collected intraoperatively from concave and convex side of the apex of the major spinal curve in AIS (N = 24) and either side from non-scoliosis patients (N = 14). Outcome measures Radiological Cobb angle and basic anthropometric data of recruited subjects were measured. The DEPs and metabolites were compared in plasma using proteomics and metabolomics technique. The relative expression of selected genes was measured in muscles. Methods Plasma samples from AIS were collected at first clinical visit and were further divided into non-progressive or progressive groups according to Cobb angle changes in six-years follow-up. Age-matched healthy girls were recruited as control. High-performance liquid chromatography-mass spectrometry based proteomic analysis was carried out in three groups to identify DEPs and their annotated metabolic pathways. An independent cohort was used for validation by gas chromatography-mass spectrometry based metabolomic analysis. Paraspinal muscles were subjected to quantitative polymerase chain reaction (qPCR) followed by correlation analysis. Human skeletal muscle myoblast (HSMM) was used as the cellular model. Results The likelihood of aberrant galactose metabolism and glycolysis was found to be associated with AIS curve progression as evidenced by the13 DEPs and 7 related metabolites according to proteomic and metabolomic analysis. Some of the DEPs showed significantly altered expression in AIS concave and convex sides paraspinal muscles compared with those in non-scoliosis control. Four DEPs were found significantly and negatively correlated with LBX1 in AIS convex side paraspinal muscles. Overexpressing LBX1 in HSMM cells led to increased expression of 3 DEPs and decreased expression of 3 DEPs, respectively. Conclusions This is the first integrated proteomic and metabolomic analysis on AIS. Our findings show dysregulated galactose metabolism and glycolysis pathways in progressive group of AIS, suggesting the presence of abnormal energy metabolism at early stage of this disease, and their association with higher risk of progressing into more severe curvature. Evidence from ex vivo study with human muscle biopsies and in vitro study with human myoblast cells propose the possible effect of LBX1 on these two pathways in skeletal muscles. The present study provides new evidence of LBX1 function in AIS via modulating effect on the expression of energy metabolism related genes. This study might provide new insights into etiopathogenesis and development of novel treatment strategy targeting on abnormal body weight and BMI in patients with AIS. Additionally, the plasma proteomic and metabolomic studies suggested new candidates as biomarkers for establishing predictive model for AIS onset/progression.
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.
Resumen La literatura que explica los mecanismos neurológicos que subyacen al desarrollo o a la compensación de la escoliosis idiopática es limitada. El objetivo del presente artículo es describir e integrar los mecanismos y las vías nerviosas por medio de las cuales se compensa y/o se desarrolla la escoliosis idiopática. Se realizó una revisión sistemática narrativa en diferentes bases de datos sobre los estudios publicados entre el 1 de enero 1967 y el 1 de abril de 2021, empleando los siguientes términos: «scoliosis», «vision», «ocular», «vestibule», «labyrinth», «posture», «balance», «eye movements», «cerebellum», «proprioception» y «physiological adaptation». En la búsqueda se identificaron 1.112 referencias, de las cuales al final se incluyeron 50: 46 estudios clínicos observacionales analítico-descriptivos (entre cohortes, reporte y serie de casos) y 4 estudios experimentales. En la respuesta neurológica a la escoliosis idiopática, la integración sensitivo-cortical de las aferencias visual-oculomotor-vestibular-propioceptiva permite realizar modificaciones a nivel postural con el fin de lograr una compensación inicial sobre el balance sagital y el centro de masa; sin embargo, con el tiempo dicho mecanismo de compensación puede agotarse y causar progresión de la deformidad inicial.
BACKGROUND: Adolescent Idiopathic Scoliosis (AIS) requires complex medical care because of multiple consequences especially on daily activities. Muscular involvement is part of the problem and may be treatable. OBJECTIVE: To analyze trunk muscle strength using an isokinetic dynamometer in female adolescents with AIS one year after orthopedic treatment by brace and compare the findings to a matched group of an asymptomatic cohort. METHODS: The trunk flexors and extensors strength was measured using an isokinetic dynamometer at 60, 90 and 120∘/s. Peak Moment (PM), Mean Power (MP) and the flexor/extensor ratio in 100 patients aged 14 to 18 years old were compared to a control group (N= 32) of asymptomatic age-matched females. In the AIS group, correlation analyses were computed to search for contributing factors to isokinetic performances, including morphological characteristics of patients, as well as clinical and radiological characteristics of the scoliosis. RESULTS: The trunk flexors in the AIS group were significantly but moderately (15%) weaker across speeds compared to their control counterparts at all speeds. No parallel weakness was noted for the extensors. While the MP of AIS patients was significantly weaker than that of the controls, 33% for flexors and by 31% for extensors, no significant differences were observed for the F/E ratios. The correlational analyses has indicated that weight and BMI were contributing factors at all speeds. CONCLUSION: Adolescents with AIS had weaker trunk extensors and mostly flexors compared to healthy females. Within this AIS population, weight and BMI seem to have a negative impact on muscular performances, whereas clinical and radiological characteristics of the scoliosis do not seem to contribute.
Scoliosis seriously affects the physical and mental health of patients. Therefore, machine learning approaches were used to predict whether the subject was scoliosis patient or not by physical characteristics and electromyography (EMG) ratios. One hundred and six subjects, including 33 healthy subjects and 73 subjects with scoliosis, have been involved in this study. However, only about half of the predictions were correct. This may because of the small dataset, and the relatively weak relationship between the features (age, height, weight, gender, and EMG ratios) and the occurrence of scoliosis. This present work served as an initial step for the application of artificial intelligence in scoliosis prediction. However, it is significant and necessary for a greater effort in this topic.
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Purpose: Idiopathic scoliosis (IS) is a frequent 3D structural deformity of the spine with a multi-factorial aetiology which remains largely unclear. In the last decade, human magnetic resonance imaging (MRI) morphometry studies (e.g. cortical thickness, 2D shape of the corpus callosum) have aimed to investigate the potential contribution of the central nervous system in the etiopathogenesis of IS. Recent developments in diffusion tensor imaging (DTI) allow us to extend the previous work to the study of white matter microstructure. Here, we hypothesized that part of the corpus callosum could show a difference in white matter microstructure in IS patients as compared to healthy controls. Methods: We acquired DTI in 10 girls with IS and in 49 gender-matched controls to quantify the fractional anisotropy (FA) along the corpus callosum. Results: Despite a very similar pattern of FA along the corpus callosum (maxima in the splenium and the genu and minimum in the isthmus), we found a significantly lower FA in the body in patients with IS as compared to control subjects. This region is known to connect the motor and premotor cortices of the two hemispheres. Conclusion: This first diffusion magnetic resonance imaging brain study in IS patients, suggests that differences in white matter development, such as synchronization of axonal myelination and pruning could be involved in the etiopathogenesis of IS.
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The aetiology of idiopathic scoliosis (IS) remains unknown, but there is growing support for the possibility of an underlying neurological disorder. Functional magnetic resonance imaging (fMRI) can characterize the abnormal activation of the sensorimotor brain network in movement disorders and could provide further insights into the neuropathogenesis of IS. Twenty subjects were included in the study; 10 adolescents with IS (mean age of 15.2, 8 girls and 2 boys) and 10 age-matched healthy controls. The average Cobb angle of the primary curve in the IS patients was 35° (range 27°-55°). All participants underwent a block-design fMRI experiment in a 1.5-Tesla MRI scanner to explore cortical activation following a simple motor task. Rest periods alternated with activation periods during which participants were required to open and close their hand at an internally paced rate of approximately 1 Hz. Data were analyzed with Statistical Parametric Mapping (SPM5) including age, sex and laterality as nuisance variables to minimise the presence of bias in the results. Compared to controls, IS patients showed significant increases in blood oxygenation level dependent (BOLD) activity in contralateral supplementary motor area when performing the motor task with either hand. No significant differences were observed when testing between groups in the functional activation in the primary motor cortex, premotor cortex and somatosensory cortex. Additionally, the IS group showed a greater interhemispheric asymmetry index than the control group (0.30 vs. 0.13, p < 0.001). This study demonstrates an abnormal pattern of brain activation in secondary motor areas during movement execution in patients with IS. These findings support the hypothesis that a sensorimotor integration disorder underlies the pathogenesis of IS.
This study sought to investigate the normal muscle fibre size and type distribution of the human erector spinae, both in thoracic and lumbar regions, in a group of 31 young healthy male (n=17) and female (n=14) volunteers. Two percutaneous muscle biopsy samples were obtained under local anaesthesia, from the belly of the left erector spinae, at the levels of the 10th thoracic and 3rd lumbar vertebrae. Samples were prepared for routine histochemistry for the identification of fibre types. Fibre size (cross-sectional area (CSA) and narrow diameter (ND)) was quantified using computerised image analysis. The mean CSA/ND for each fibre type was greater in the thoracic than the lumbar region, but there was no difference between the 2 regions either for percentage type I (i.e. percentage distribution by number), percentage type I area (i.e. relative area of the muscle occupied by type I fibres) or the ratio describing the size of the type I fibre relative to that of the type II. Men had larger fibres than women, for each fibre type and at both sampling sites. In the men, each fibre type was of a similar mean size, whereas in the women the type I fibres were considerably larger than both the type II A and type II B fibres, with no difference between the latter two. In both regions of the erector spinae there was no difference between men and women for the proportion (%) of a given fibre type, but the percentage type I fibre area was significantly higher in the women.
Despite its high prevalence, the etiology underlying idiopathic scoliosis remains unclear. Although initial scrutiny has focused on genetic, biochemical, biomechanical, nutritional and congenital causes, there is growing evidence that aberrations in the vestibular system may play a role in the etiology of scoliosis. In this article, we discuss putative mechanisms for adolescent idiopathic scoliosis and review the current evidence supporting a role for the vestibular system in adolescent idiopathic scoliosis. A comprehensive search of the English literature was performed using PubMed ( ). Research articles studying interactions between adolescent idiopathic scoliosis and the vestibular system were selected and evaluated for inclusion in a literature review. Eighteen manuscripts of level 3-4 clinical evidence to support an association between adolescent idiopathic scoliosis (AIS) and dysfunction of the vestibular system were identified. These studies include data from physiologic and morphologic studies in humans. Clinical data are supported by animal model studies to suggest a causative link between the vestibular system and AIS. Clinical data and a limited number of animal model studies suggest a causative role of the vestibular system in AIS, although this association has not been reproduced in all studies.
Scoliosis refers to curves exceeding 10 degrees observed through posterioanterior direct radiography. In fact, the diagnosis for idiopathic scoliosis is accepted to exclude already available causes. The aim of this paper was to review the etiopathogenesis, classification systems and the treatment management of idiopathic scoliosis. A search in the National Library of Medicine (Pubmed) database using the key words 'idiopathic' and 'scoliosis' was performed. For the literature review, papers concerning the etiopathogenesis, classification and treatment were selected among these articles. A search in the National Library of Medicine (Pubmed) database using the key words 'idiopathic' and 'scoliosis' yielded 4518 articles published between 1947 and 2013. The main hypothesis put forward included genetic factors, hormonal factors, bone and connective tissue anomalies. King, Lenke, Coonrad and Peking Union Medical College (PUMC) classifications were the main classification systems for idiopathic scoliosis. Exercise, bracing and anterior, posterior or combined surgery when indicated are the choices for the treatment. Every idiopathic scoliosis case has to be managed to its own characteristics. It is the post-operative appearance that the surgeons are perhaps the least interested but the adolescent patients the most interested in. The aim of scoliosis surgery is to restore the spine without neurological deficit.
Disturbed somatosensory evoked potentials have been demonstrated in patients with adolescent idiopathic scoliosis (but this functional delay was found to originate above the C5-6 level, while the lower cord level was unaffected). Together with MR imaging observation of tonsillar ectopia and a relatively tethered cord, we hypothesized that there is disturbed mean diffusivity integrity along the spinal cord. In this study, advanced DTI was used to evaluate whether there was underlying decreased WM integrity within the brain stem and spinal cord in adolescent idiopathic scoliosis and any relationship to cerebellar tonsillar ectopia. Clinical impact on balance testing was also correlated. Thirteen girls with adolescent idiopathic scoliosis with right thoracic curves were compared with 13 age-matched healthy girls. DTI of the brain and whole spinal cord was performed. ROIs were manually defined for the medulla oblongata and along each intervertebral segment of the cord. Mean values of fractional anisotropy and mean diffusivity were computed at the defined regions. Between-group comparisons were performed by 1-way ANOVA. Significantly decreased fractional anisotropy values and increased mean diffusivity values were found at the medulla oblongata and C1-2, C2-3, C3-4, and C4-5 segments in patients with adolescent idiopathic scoliosis compared with healthy subjects. No significant difference was found in the lower cord levels. Significant correlation was found between the tonsillar level and fractional anisotropy value at the C4-5 level in patients with adolescent idiopathic scoliosis only. The findings from this study are in agreement with previous findings showing abnormal somatosensory evoked potential readings occurring only above the C5-6 level in patients with adolescent idiopathic scoliosis; these findings might partially explain the pathophysiology of the neural pathway involved.
The cause of adolescent idiopathic scoliosis (AIS) in humans remains obscure and probably multifactorial. At present, there is no proven method or test available to identify children or adolescent at risk of developing AIS or identify which of the affected individuals are at risk of progression. Reported associations are linked in pathogenesis rather than etiologic factors. Melatonin may play a role in the pathogenesis of scoliosis (neuroendocrine hypothesis), but at present, the data available cannot clearly show the role of melatonin in producing scoliosis in humans. The data regarding human melatonin levels are mixed at best, and the melatonin deficiency as a causative factor in the etiology of scoliosis cannot be supported. It will be an important issue of future research to investigate the role of melatonin in human biology, the clinical efficacy, and safety of melatonin under different pathological situations. Research is needed to better define the role of all factors in AIS development.
Study Design. Prospective clinical electromyographic study in adolescents with idiopathic scoliosis and control group. Objective. To evaluate electromyographic amplitude from erector spinae muscles of patients with idiopathic scoliosis in comparison with control volunteers without spinal deformities. Summary of Background Data. Previous studies have indicated an increased electromyographic activity in paravertebral muscles in the convex side of the scoliotic curvature. However, in previous studies there is the absence or poor description of methods used, and some studies were conducted before the recording and processing recommendations for surface electromyographic signals had been described. Methods. Thirty individuals, matched by sex, age, and body mass index, were divided into two groups: scoliosis and control. The electric activity of the erector spinae muscles was determined by surface electromyography on both sides of the three levels of spine: T8, L2, and L5. Results. Normalized electromyographic amplitudes of erector spinae muscles, in the convex and concave sides of the apex region of the scoliotic curve in the thoracic and lumbar regions, were not significantly different. Also, there was no significant difference between the muscles of these regions when the scoliosis group was compared with the control group. The erector spinae muscle at the L5 level, representing the lower vertebral limit of the lumbar scoliotic curve, had significantly higher electromyographic activity on the convex side. However, the same alteration was shown in the control group homologous muscle (on the left side). Conclusion. Erector spinae muscles on the convex and concave sides at the curvature apex in patients with idiopathic scoliosis and small magnitude of curves did not show significant differences in electromyographic amplitude. Future studies should evaluate whether intragroup activation differences, at the L5 level in 80% of the maximum voluntary isometric contractions with predominance of the left side of the vertebral column, have any relation to the condition.