Brain anatomy differences in childhood stuttering

Abstract

Stuttering is a developmental speech disorder that occurs in 5% of children with spontaneous remission in approximately 70% of cases. Previous imaging studies in adults with persistent stuttering found left white matter deficiencies and reversed right-left asymmetries compared to fluent controls. We hypothesized that similar differences might be present indicating brain development differences in children at risk of stuttering. Optimized voxel-based morphometry compared gray matter volume (GMV) and diffusion tensor imaging measured fractional anisotropy (FA) in white matter tracts in 3 groups: children with persistent stuttering, children recovered from stuttering, and fluent peers. Both the persistent stuttering and recovered groups had reduced GMV from normal in speech-relevant regions: the left inferior frontal gyrus and bilateral temporal regions. Reduced FA was found in the left white matter tracts underlying the motor regions for face and larynx in the persistent stuttering group. Contrary to previous findings in adults who stutter, no increases were found in the right hemisphere speech regions in stuttering or recovered children and no differences in right-left asymmetries. Instead, a risk for childhood stuttering was associated with deficiencies in left gray matter volume while reduced white matter integrity in the left hemisphere speech system was associated with persistent stuttering. Anatomical increases in right hemisphere structures previously found in adults who stutter may have resulted from a lifetime of stuttering. These findings point to the importance of considering the role of neuroplasticity during development when studying persistent forms of developmental disorders in adults.

Altered effective connectivity and anomalous anatomy in the basal ganglia-thalamocortical circuit of stuttering speakers

“…Jä ncke et al (2004) and Beal et al (2007) also reported similar findings that stuttering adults demonstrated increased WM volume concentration in the right frontal cortex (including the anterior middle frontal gyrus, inferior frontal gyrus, and precentral gyrus) and temporal cortex (the superior temporal gyrus). In contrast, no such increases of volume concentration were found in stuttering children (Chang et al, 2008). Thus, these results suggest an increased intrahemispheric communication within these areas and a possible dysfunction in the left frontal and temporal cortex in stuttering speakers.…”

“…However, Sommer et al (2002) and Watkins et al (2008) found lower fractional anisotropy (FA) value in the left rolandic operculum (RO)/FO immediately above the Sylvian fissure in stuttering adults. Chang et al (2008) found the same result in stuttering children. Considering the small sample size of the present study and the limitations of VBM methods, we might have failed to detect anatomical differences in this region.…”

“…Previous research has documented both functional and anatomical differences in certain regions of the brain between stuttering and non-stuttering speakers (Brown et al, 2005;Chang et al, 2008;Jä ncke et al, 2004). Little is known, however, about effective connectivity among these regions in relation to stuttering.…”

“…Braun et al's (1997) conclusion is also consistent with the most recent data on the structural differences in the brain between stuttering children and adults. Among stuttering children, anatomical abnormality is found in the left hemisphere (Chang et al, 2008), whereas among stuttering adults, many anatomical abnormalities are evident in the right hemisphere (Jä ncke et al, 2004). It appears that anatomical abnormality in the left hemisphere is responsible for stuttering, but a lifetime of stuttering can also lead to changes in the compensatory areas in the contralateral (right) hemisphere (Chang et al, 2008).…”

“…Among stuttering children, anatomical abnormality is found in the left hemisphere (Chang et al, 2008), whereas among stuttering adults, many anatomical abnormalities are evident in the right hemisphere (Jä ncke et al, 2004). It appears that anatomical abnormality in the left hemisphere is responsible for stuttering, but a lifetime of stuttering can also lead to changes in the compensatory areas in the contralateral (right) hemisphere (Chang et al, 2008). Based on these results, the present study focused on the functional and structural abnormality in the left hemisphere of the stuttering speakers.…”