Patterns of Structural Reorganization of the Corticospinal Tract in Children With Sturge-Weber Syndrome

Abstract

Background Reorganization of the corticospinal tract (CST) after early damage can limit motor deficit. In this study, we explored patterns of structural CST reorganization in children with Sturge-Weber syndrome. Methods Five children (age 1.5-7 years) with motor deficit due to unilateral Sturge-Weber syndrome were studied prospectively and longitudinally (1-2 years follow-up). CST segments belonging to hand and leg movements were separated, and their volume was measured by diffusion tensor imaging (DTI) tractography using a recently validated method. CST segmental volumes were normalized and compared between the SWS children and age-matched healthy controls. Volume changes during follow-up were also compared to clinical motor symptoms. Results In the SWS children, hand-related (but not leg-related) CST volumes were consistently decreased in the affected cerebral hemisphere at baseline. At follow-up, two distinct patterns of hand CST volume changes emerged: (i) Two children with extensive frontal lobe damage showed a CST volume decrease in the lesional hemisphere and a concomitant increase in the non-lesional (contralateral) hemisphere. These children developed good hand grasp but no fine motor skills. (ii) The three other children, with relative sparing of the frontal lobe, showed an interval increase of the normalized hand CST volume in the affected hemisphere; these children showed no gross motor deficit at follow-up. Conclusions DTI tractography can detect differential abnormalities in the hand CST segment both ipsi- and contralateral to the lesion. Interval increase in the CST hand segment suggests structural reorganization, whose pattern may determine clinical motor outcome and could guide strategies for early motor intervention.

Detection of hand and leg motor tract injury using novel diffusion tensor MRI tractography in children with central motor dysfunction

“…The population in the present study had a wider age range (1-20 years vs. 1-14 years in the previous study), and non-linear fitting of normalized volumes demonstrated, for the first time, an early CST-specific age-related increase in both hand and leg motor segments which reached their maxima around age 5-6 years, followed by a sharp decline in the next 5-6 years of age, and subsequently a flattening out after adolescence. Similar to our previous findings [16], the age-related correlations were the strongest in the right leg-related CST segments. However, the curves showed a similar pattern (although with weaker correlations) in the hand segments, and, to the least degree, in the left leg segment as well.…”

“…The use of both absolute and normalized CST volumes provided a more comprehensive insight into normal CST maturation; although normalized volumes are affected by whole-brain changes, they have the advantage of providing data more specific for CST after taking out the effect of global white matter variations. Therefore, these data refine our recent results demonstrating an age-related decrease of right CST leg segments in children with normal motor functions [16]. The population in the present study had a wider age range (1-20 years vs. 1-14 years in the previous study), and non-linear fitting of normalized volumes demonstrated, for the first time, an early CST-specific age-related increase in both hand and leg motor segments which reached their maxima around age 5-6 years, followed by a sharp decline in the next 5-6 years of age, and subsequently a flattening out after adolescence.…”

“…To overcome this critical problem, we recently developed a new method, independent component analysis combined with ball-stick model (ICA+BSM) allowing identification and isolation of crossing fibers related to control of the hands and legs [12-15]. Using this approach, it was found that in children with unilateral brain damage due to Sturge-Weber syndrome, hand-related (but not leg-related) CST volumes were consistently decreased in the affected hemisphere [16]. Follow-up showed that depending on the level of brain damage, varying degrees of compensation occurred as reflected by changes in CST volume [16].…”

“…Using this approach, it was found that in children with unilateral brain damage due to Sturge-Weber syndrome, hand-related (but not leg-related) CST volumes were consistently decreased in the affected hemisphere [16]. Follow-up showed that depending on the level of brain damage, varying degrees of compensation occurred as reflected by changes in CST volume [16]. Another study demonstrated that asymmetries also exist between the development of hand- and leg- related fibers of the CST in typically developing children [17].…”

Deep cerebral vein expansion with metabolic and neurocognitive recovery in Sturge–Weber syndrome

“…Contralateral changes have been also documented by FDG‐PET in the form of increased cortical metabolism, mostly affecting posterior regions including the visual cortex 12, 13, 14. In addition, DTI fiber tractography studies showed signs of strengthening of the contralateral central motor and visual pathways in some SWS children with preserved motor and visual functions, respectively 13, 15…”