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Introduction: Different subclinical neurological dysfunction has been reported in AIS, including poor postural control and asymmetric otolith vestibulo-ocular responses compared with normal controls. Objectives: The objective of this study is to establish whether abnormal MRI morphoanatomical changes arise in vestibular system (VS) in AIS when compared with controls using computational morphometry techniques. Materials and methods: High resolution T2W images of VS of 19 right-thoracic AIS and 12 age-matched controls were acquired. A best-fit plane and a best-fit circle were calculated to approximate each semicircular canal. The shape of VS was measured by the length and angle formed by the lines connecting the centres of each pair of best-fit circles, the radius of the circles, and the rotational angles and compared the rotational angles around three axes of coordinate system. Statistical analysis was done with one-way ANOVA. Results: Significant difference in the shape of left-side semicircular canals between AIS and controls: (1) distance between the centers of the lateral and superior canals (p=0.007) (AISNC). No significance group difference was found in right-side VS. (4) Orientation asymmetry between left-side and right-side VS along z axis (p=0.0067) (AIS>NC). Conclusion and significance: These morphological changes are likely to be related to subclinical postural, vestibular, and proprioceptive dysfunctions. Further association studies and longitudinal studies could help to further define the link between morphological and functional dysfunction, which might have important predictive and prognostic effect on curve development and progression. [ABSTRACT FROM AUTHOR]

Introduction: Previous statistical analysis of the brain MRI in AIS and normal controls (NC) suggested there were regional differences in the splenium of corpus callosum and left internal capsule. Cortical thinning has been reported during normal brain maturation in adolescence. Objectives: The objective of this study is to investigate the brain maturation by cerebral cortical thickness (CCT) among AIS and NC. Materials and methods: Fifty AIS patients were with moderate-to-severe (i.e., Cobb angle≥20°) right-thoracic curves (9 moderate; 41 severe; mean Cobb angle=48.7°, range=20°~90°; mean age=14.46 yrs; age range=12~17 yrs). Forty age-matched NC were recruited from local schools. Based on the T1W MRI, CCT was calculated using Freesurfer. Results: CCT declined significantly in almost all cortical lobes in NC (ρ<-0.4; P≤0.05) except temporal lobe in left hemisphere, while in AIS this decline was weakly correlated with age (ρ>-0.4). For example, CCTs of the right hemisphere at the age of 13-16 yrs in AIS were 2.46mm, 2.49mm, 2.49mm, and 2.45mm respectively, and in NC were 2.55mm, 2.49mm, 2.46mm, and 2.42mm respectively. Quadratic regression expressed detailed difference in the age-related cortical changing pattern between the two groups. Focal CCT was significantly different in AIS patients compared with healthy controls in areas involved in motor and vestibular functions as well as object recognition. Conclusion and significance: The findings from this study imply a different thinning pattern of the cerebral cortex during adolescence in patients with AIS; this may be primary (i.e. etiopathogenetic) or secondary (i.e. adaptation) to the development of scoliosis. [ABSTRACT FROM AUTHOR]

Introduction: Previous statistical morphometric analysis of the brain MRI in Adolescent Idiopathic Scoliosis (AIS) patients and normal controls suggested there were statistically significant regional differences in the white matter. Objectives: The aim of this study was to qualitatively and quantitatively identify the differentiation of the cortical thickness between the right-curve AIS patients and the age-matched normal controls. Materials and Methods: The comparative study involved T1W MRI data acquired using FFE sequence on 20 right-curve AIS subjects and 20 age-matched normal controls. The white matter and pial surfaces were automatically segmented, from which the cortical thickness values were calculated. The Freesurfer software was applied to perform the cortical parcellation, cortical thickness calculation, and statistical analysis. Results: Compared to normal controls, significantly increased thickness was detected in cortical surface of the right-thoracic AIS subjects around their middle parts of the superior frontal lobe in the left hemisphere (P<0.001). Conclusion and Significance: The detected result implies the faster development in the superior frontal lobe in AIS subjects, which might be caused by their excessive attention and planning in their body movements. Moreover, it might also be associated with their emotional responses for not being socially acceptable as norms. [ABSTRACT FROM AUTHOR]

Previous studies have documented obstructed CSF flow in patients with Chiari I malformation. Low-lying cerebellar tonsils and syringomyelia are also observed in AIS patients. We sought to investigate whether disturbed CSF flow is also evident in AIS subjects at the foramen magnum level and its relationship with level of cerebellar tonsils and dimensions of foramen magnum. Phase-contrast and conventional MR were performed in 105 adolescent girls, which include 69 AIS subjects (Cobbs angle 20–80, 40 had thoracic curve, 27 lumbar curve, 2 thoracolumbar curve) and 36 age-matched controls. Measurements of peak velocity of CSF flow in both the anterior and posterior subarachnoid space through foramen magnum, cerebellar tonsillar level related to the basion-opsithion (BO) line, anteroposterior (AP), transverse (TS) diameter and area of foramen magnum were obtained. Correlations were made among different parameters and SSEP findings. Peak CSF velocities through foramen magnum showed no significant difference (p>0.05) between AIS and normal subjects though 42% subjects in AIS group had the cerebellar tonsillar tip positioned 1 mm below the BO line. The cerebellar tonsillar level in AIS subjects was significantly lower than the median tonsillar level in normal controls (p<0.01) while the AP diameter and area of foramen magnum were significantly larger in AIS subjects when compared with normal controls (p<0.05). Peak CSF velocities through foramen magnum were not significantly different in AIS subjects despite the presence of low-lying cerebellar tonsils. This might be explained by the compensatory effect of larger foramen magnum in AIS subjects. [ABSTRACT FROM AUTHOR]

Observation of sub-clinical neurological abnormalities has led to proposal of neuro-developmental etiologic model for AIS. Longer latency in somatosensory–evoked potential (SSEP) and impaired balance control have been demonstrated in AIS subjects. In this study, we investigated whether regional brain tissue densities in AIS patients differ from matched control subjects. Nine left thoracic AIS girls (mean Cobbs angle 19°) and 11 matched controls; 20 right thoracic AIS girls (mean Cobbs 33.8°) and 17 matched controls underwent MR imaging of the brain. Fully automatic morphometric analysis was used to analyse the MR images; it included linear registration to a template brain and brain-tissue classification into grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF). Tissue densities were compared between AIS subjects and controls. There was no significant difference between AIS subjects and normal controls when comparing absolute and relative (i.e. brain-size adjusted) volumes of grey and white matter. Using voxel-based morphometry, significant group differences (Controls > left AIS) were found in density of WM, in genu of corpus callosum, left internal capsule (anterior arm) and WM underlying orbitofrontal cortex of the left hemisphere. The above difference was not observed in right AIS group. Corpus callosum, major commissural fiber responsible for controlling the balance of right and left side of the body, was different in atypical left scoliosis while significant regional brain changes have not yet found in those with typical right thoracic scoliosis. Further investigation is warranted to see whether the above discrepancy is related to laterality of the scoliotic curve. [ABSTRACT FROM AUTHOR]

Balance dysfunction has been reported to be associated with adolescent idiopathic scoliosis (AIS). This study sought to investigate for any morphometric difference present in vestibular system between AIS subjects and normal controls. High resolution T2W MR images of vestibular systems were obtained from 13 AIS girls with normal postural balance (PB), 9 PB-abnormal AIS girls and 20 matched controls. The 3D vestibular system surfaces were segmented by automatic computational pipeline. One best fit circle was assigned to each of the three semicircular canals. Shape of each canal was reflected by the radius of its circle while spatial relationship among the three canals was reflected by the length and angle formed between the corresponding lines connecting the centers of each pair of circles. Orientation asymmetry between left and right vestibular systems was measured by the Euler angles calculated to rigidly register the right to left vestibular surface. Statistical analysis was performed using one-way ANOVA. There was significant group difference in the shape and spatial relationship of the semicircular canals. In general, AIS had greater orientation asymmetry between left and right vestibular systems when compared with normal controls (p=0.0265). This difference was more exaggerated in PB-abnormal AIS (p=0.016). Mean values of rotational angles around y-axis were as follows: control=-2.8593, PB-normal AIS=-1.0949, PB-abnormal AIS=3.7309. Rotational asymmetry of the vestibular system might be one of the factors leading to postural dysfunction in AIS. Whether this structural change has any prognostic effect on curve progression warrants further longitudinal investigation. [ABSTRACT FROM AUTHOR]

The parietal bone contour was more prominent while occipital bone contour was significantly smaller in adolescent idiopathic scoliosis (AIS) subjects. AIS also had shorter hypophyseal fossa and longer clivus in the basicranium when compared with normal controls. These observations can be accounted by a mismatch between membranous (calvarium) and endochondral (basicranium) ossification, which affecting the skull and vertebral column as a systemic process of abnormal skeletal growth in AIS. Abnormal skeletal growth in Adolescent Idiopathic Scoliosis (AIS) girls is observed in the vertebral column with a mismatch between endochondral and membranous ossifications. This study sought to investigate whether an abnormal growth pattern also affecting the skull resulting in morphological differences in the calvarium and basicranium between AIS girls and normal controls. The analysis was based on high resolution magnetic resonance imaging (MRI) and computer-assisted morphometric analysis. MRI images of the whole skull were obtained from 28 AIS girls (age 12–18, Cobbs angle >40 degrees) and 18 matched healthy controls. First, the shape of the calvarium (formed by membranous ossification) was assessed by computer-assisted 3D morphometric analysis with shape description. The configuration of basicranium (formed by endochondral ossification and without clear boundary on 3D image) was assessed on the best mid-sagittal image with both linear and angular measurements of the pre-defined anatomical points on the skull base. For the calvarium, the occipital contour was significantly smaller while the left parietal contour was more prominent in AIS subjects (Recursive feature elimination for support vector machine, SVM_RFE). For the basicranium, the length of hypophyseal fossa housing the pituitary gland was significantly shorter in AIS girls (p<0.05) and the length of clivus including the basioccipital synchondrosis was significantly longer in AIS girls (p<0.05). The present study suggests that abnormal skeletal growth is a systemic process in AIS, affecting not only their vertebral columns but also their skulls. These could be accounted by a mismatch between membranous (circumferential growth of vertebral column and calvarium) and endochondral (longitudinal growth of vertebral column and basicranium) ossification. The clinical significance of morphometric changes of the calvarium and basicranium is closely related to whether corresponding changes are present in the underlying cerebral structures. [ABSTRACT FROM AUTHOR]