Variation in anisotropy and diffusivity along the medulla oblongata and the whole spinal cord in adolescent idiopathic scoliosis: a pilot study using diffusion tensor imaging.
OBJECTIVE
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
From the Departments of Imaging and Interventional Radiology (Y.K., L.S., S.C.N.H., D.W., M.D., W.C.W.C.).
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Y
Kong
From the Departments of Imaging and Interventional Radiology (Y.K., L.S., S.C.N.H., D.W., M.D., W.C.W.C.)Shenzhen Institutes of Advanced Technology (L.S.), Chinese Academy of Sciences, Shenzhen, China.
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Shi
From the Departments of Imaging and Interventional Radiology (Y.K., L.S., S.C.N.H., D.W., M.D., W.C.W.C.).
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SC
Hui
From the Departments of Imaging and Interventional Radiology (Y.K., L.S., S.C.N.H., D.W., M.D., W.C.W.C.)Biomedical Engineering and Shun Hing Institute of Advanced Engineering (D.W.)The Chinese University of Hong Kong Shenzhen Research Institute (D.W.), Shenzhen, China. dfwang@cuhk.edu.hk winnie@med.cuhk.edu.hk.
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Wang
From the Departments of Imaging and Interventional Radiology (Y.K., L.S., S.C.N.H., D.W., M.D., W.C.W.C.).
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M
Deng
From the Departments of Imaging and Interventional Radiology (Y.K., L.S., S.C.N.H., D.W., M.D., W.C.W.C.) dfwang@cuhk.edu.hk winnie@med.cuhk.edu.hk.
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Chu
Orthopaedics and Traumatology (J.C.Y.C.), The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
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Cheng
D000293:Adolescent; D016880:Anisotropy; D056324:Diffusion Tensor Imaging; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006801:Humans; D008526:Medulla Oblongata / Q000503:physiopathology*; D010865:Pilot Projects; D012600:Scoliosis / Q000503:physiopathology*; D013116:Spinal Cord / Q000503:physiopathology*