A voxel-based morphometry (VBM) analysis of regional grey and white matter volume abnormalities within the speech production network of children who stutter

Abstract

It is well documented that neuroanatomical differences exist between adults who stutter and their fluently speaking peers. Specifically, adults who stutter have been found to have more grey matter volume (GMV) in speech relevant regions including inferior frontal gyrus, insula and superior temporal gyrus (Beal et al., 2007; Song et al., 2007). Despite stuttering having its onset in childhood only one study has investigated the neuroanatomical differences between children who do and do not stutter. Chang et al. (2008) reported children who stutter had less GMV in the bilateral inferior frontal gyri and middle temporal gyrus relative to fluently speaking children. Thus it appears that children who stutter present with unique neuroanatomical abnormalities as compared to those of adults who stutter. In order to better understand the neuroanatomical correlates of stuttering earlier in its development, near the time of onset, we used voxel-based morphometry to examine volumetric differences between 11 children who stutter and 11 fluent children. Children who stutter had less GMV in the bilateral inferior frontal gyri and left putamen but more GMV in right Rolandic operculum and superior temporal gyrus relative to fluent children. Children who stutter also had less white matter volume bilaterally in the forceps minor of the corpus callosum. We discuss our findings of widespread anatomic abnormalities throughout the cortical network for speech motor control within the context of the speech motor skill limitations identified in people who stutter (Namasivayam and van Lieshout, 2008; Smits-Bandstra et al., 2006).

Keywords: Magnetic resonance imaging (MRI); Persistent developmental stuttering; Speech motor control; Voxel-based morphometry.

Figure 1

Sample axial slices (z = 0) of the custom paediatric templates used for spatial normalization in the current study. Shown above in (A) is the T1 template, (B) the segmented grey matter tissue prior and (C) the segmented white matter tissue prior.

Figure 2

Statistical parametric maps of the regionalized grey and white matter volume differences (threshold at p<.001, uncorrected) found between children who do and do not stutter overlaid on axial slices of the custom paediatric T1 template. Images are displayed in neurological convention (left is left). The regions where the children who stutter demonstrated significantly less grey and white matter volume than controls are shown in red and green respectively. The regions where the children who stutter demonstrated significantly more grey matter volume than controls are shown in yellow. No regions of increased white matter volume were found in the children who stutter relative to the controls. The z-level of the axial slice on display from the custom paediatric template is reported beneath each image.