Structure-function abnormalities in cortical sensory projections in embouchure dystonia

Abstract

Highlights Abnormal diffusion metrics are observed in sensory(motor) projections in ED. Left S1-putamen trajectory diffusion changes associate with putaminal FC reduction. Sensory cortex-related changes support a key role of sensory dysfunction in ED.

Structural magnetic resonance imaging in dystonia: A systematic review of methodological approaches and findings

“…For dMRI studies, using more diffusion directions can improve the precision of the calculated diffusion tensor, and a greater degree of diffusion weighting (a higher b value) can enable assessment of more subtle diffusion properties but with the trade‐off of increased potential for artifacts and lower signal to noise ratio. Of the studies identified, the number of diffusion directions ranged from 6 ( n = 5) [9–13] to ≥60 ( n = 18) [14, 31, 33, 35, 37, 39, 42–45, 49–51, 54, 57–59, 63], the remaining studies using an intermediate number of directions ( n = 10) [30, 32, 34, 36, 38, 40, 41, 46, 52, 53, 55, 56, 60–62, 64–68, 70] or no details were provided ( n = 1) [15]. The b values employed were in typical ranges of 700–1000 s/mm 2 , with five higher at 1100–1500 s/mm 2 [38, 39, 49–51].…”

“…Of the studies identified, the number of diffusion directions ranged from 6 ( n = 5) [9–13] to ≥60 ( n = 18) [14, 31, 33, 35, 37, 39, 42–45, 49–51, 54, 57–59, 63], the remaining studies using an intermediate number of directions ( n = 10) [30, 32, 34, 36, 38, 40, 41, 46, 52, 53, 55, 56, 60–62, 64–68, 70] or no details were provided ( n = 1) [15]. The b values employed were in typical ranges of 700–1000 s/mm 2 , with five higher at 1100–1500 s/mm 2 [38, 39, 49–51].…”

“…The former involves targeted analysis of predefined locations/tracts, allowing a hypothesis‐driven approach, whilst a whole brain approach requires balancing the risk of false positive results (with inadequate multiple comparison correction) or false negative results (with more stringent correction), but does allow a more comprehensive analysis. Of the studies, 23 undertook a targeted, region‐based approach [12, 13, 16, 20, 21, 34, 35, 38, 39, 41–43, 48, 50, 51, 60, 62, 64, 65, 67, 69, 70, 73] and 28 a whole brain or whole grey/white matter‐based approach [17–19, 22–25, 27–29, 31, 32, 44, 45, 54, 55, 57, 59, 63, 66, 68, 72, 74–79]. The remaining 22 studies combined these approaches [9–11, 14, 15, 26, 30, 33, 36, 37, 40, 46, 47, 49, 52, 53, 56, 58, 61, 71, 80, 81], with five identifying the more specific regions post hoc using data from the whole brain analysis [9–11, 33, 53], an approach which has the potential to bias results.…”

“…Imaging data analysis, particularly using whole brain approaches, can involve multiple comparisons over thousands of voxels, increasing the risk of type I errors. Commonly employed multiple comparison correction approaches identified in this review included the Bonferroni correction ( n = 14) [16, 26, 29, 36, 37, 42, 43, 49, 51, 59, 62, 64, 68, 71], false discovery rate correction ( n = 13) [11, 14, 17, 20, 22, 34, 40, 41, 50, 72, 77–79] and family wise error based correction ( n = 19) [15, 21, 23, 27, 28, 31–33, 46, 54, 55, 58, 66, 67, 69–71, 75, 80, 81]. Several studies also analysed voxels as a cluster in the ROI, reducing the potential impact of multiple comparisons, either by setting cluster‐extent thresholds with p values within certain limits ( p < 0.025 to p < 0.001, n = 12) [9, 10, 15, 25, 29–31, 33, 44, 60, 61, 67, 70, 73, 74, 76, 79], or by using threshold‐free cluster enhancement ( n = 6) [14, 32, 33, 52, 58].…”

“…Amongst the dMRI studies that took a regional approach, either this involved calculating properties of interest within the region of interest (ROI), as seen in 19 studies [9, 10, 12–15, 33, 40–43, 53, 56, 60–62, 65, 67, 70], or alternatively the ROIs can act as seed points to map white matter (WM) pathways using tractography ( n = 18) [11, 30, 34–39, 41, 46, 49–51, 53, 60–62, 64]. Untargeted approaches commonly employed included voxel‐based analysis (a voxel‐by‐voxel based approach looking at whole brain diffusion tensor measures) ( n = 8) [9–11, 15, 37, 40, 61, 66].…”