What is the Difference Between Sagittal with Metopic and Isolated Sagittal Craniosynotosis? A Whole Brain Intrinsic Connectivity and Diffusion Tensor Imaging Study
Raysa Cabrejo, BA1, Cheryl Lacadie, B.S.1, Carolyn Chuang, MD, MHS1, Jenny Yang, MD, MHS1, Alexander Sun, BS1, Eric Brooks, MD, MHS1, Joel Beckett, MD, MHS1, Kyle Gabrick, MD1, Derek Steinbacher, DMD, MD1, Michael Alperovich, MD, MSc1, Kevin Pelphrey, PhD2, Todd Constable, PhD1, John Persing, MD1.
1Yale School of Medicine, New Haven, CT, USA, 2George Washington University, Washington, DC, USA.
The purpose of this study is to understand the neurological differences between patients born with combined sagittal and metopic craniosynostosis (SMc) and isolated sagittal craniosynostosis (ISc).
The authors collected diffusion tensor imaging (DTI) and resting-state functional connectivity MRI (fMRI) data in eight infant patients: four in the SMc group (5.1±1 months of age) and four in the ISc group (4.6±0.9 months of age). Resting state fMRI and DTI data were acquired using a 3-T Siemens Trio MRI system (Erlangen, Germany) while the infant patients slept without sedation. fMRI data was corrected for movement using SPM (University College London, UK), underwent cerebrospinal fluid and white matter signal regression and further analyzed with BioImageSuite (Yale University, USA). For the DTI data, three diffusions run were averaged, processed utilizing FMRIB Software Library (Oxford University, UK), and analyzed statistically using BioImageSuite (Yale University, USA).
fMR and DTI data for SMc demonstrated that there was statistically significant increased connectivity in the right Broadmann Area (BA) 9 corresponding to the dorsolateral prefrontal cortex (DLPFC). Decreased connectivity in the right BA 31
and BA 23 corresponding to the posterior cingulate cortex (PCC) (p<0.001) was also noted. Analysis of the DTI revealed increased fractional anisotropy in the SMc group in the cingulum compared to the ISc group (p<0.05).
“Functional brain connectivity” or the association of timing of similar activation of areas of the brain, is studied utilizing fMRI, as it measures differences in blood oxygenation throughout the brain. Lower connectivity, where there is less simultaneous oxygen utilization of the region, and higher connectivity where there is increased oxygenation. The SMc had decreased connectivity in the DLPFC, an area important in executive function such as working memory and abstract reasoning.1 The SMc also had increased connectivity in the in the posterior cingulate cortex, an area associated with attention deficit hyperactivity disorder.2 White matter microstructure is studied using a measurement of anisotropy of water molecules throughout the brain using DTI. “Anisotropy” measures the bidirectional resistance of water molecules in the cerebral white matter. Anisotropy increases in the normally developing brain due to the increase myelination, reduction in brain water, and the compactness of fiber tract.3 The DTI analysis demonstrated an increased in fractional anisotropy in SMc group in the cingulum, nerve tracts projecting from the cingulate cortex to connect the limbic system involved with emotions and learning. In SMc vs ISc, increase in connectivity of the PCC correlates with an increase in maturation of the
cingulum. The SMc increase in maturation could be leading to a difference in processing attention or emotions within the two groups.
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Tomasi, D. & Volkow, N. D. Abnormal Functional Connectivity in Children with Attention-Deficit/Hyperactivity Disorder. Biol. Psychiatry 71, 443–450 (2012).
Mukherjee, P. et al. Normal Brain Maturation during Childhood: Developmental Trends Characterized with Diffusion-Tensor MR Imaging. Radiology 221, 349–358 (2001).
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