Cortical Somatosensory Reorganization in Children with Spastic Cerebral Palsy: A Multimodal Neuroimaging Study

Abstract

Although cerebral palsy (CP) is among the most common causes of physical disability in early childhood, we know little about the functional and structural changes of this disorder in the developing brain. Here, we investigated with three different neuroimaging modalities [magnetoencephalography (MEG), diffusion tensor imaging (DTI), and resting-state fMRI] whether spastic CP is associated with functional and anatomical abnormalities in the sensorimotor network. Ten children participated in the study: four with diplegic CP (DCP), three with hemiplegic CP (HCP), and three typically developing (TD) children. Somatosensory (SS)-evoked fields (SEFs) were recorded in response to pneumatic stimuli applied to digits D1, D3, and D5 of both hands. Several parameters of water diffusion were calculated from DTI between the thalamus and the pre-central and post-central gyri in both hemispheres. The sensorimotor resting-state networks (RSNs) were examined by using an independent component analysis method. Tactile stimulation of the fingers elicited the first prominent cortical response at ~50 ms, in all except one child, localized over the primary SS cortex (S1). In five CP children, abnormal somatotopic organization was observed in the affected (or more affected) hemisphere. Euclidean distances were markedly different between the two hemispheres in the HCP children, and between DCP and TD children for both hemispheres. DTI analysis revealed decreased fractional anisotropy and increased apparent diffusion coefficient for the thalamocortical pathways in the more affected compared to less affected hemisphere in CP children. Resting-state functional MRI results indicated absent and/or abnormal sensorimotor RSNs for children with HCP and DCP consistent with the severity and location of their lesions. Our findings suggest an abnormal SS processing mechanism in the sensorimotor network of children with CP possibly as a result of diminished thalamocortical projections.

Motor, sensory and executive function brain networks in children with unilateral cerebral palsy

“…Laterality indices were shown to correlate with FA in the posterior limb of the internal capsule 174 as well as improve with constraint induced movement therapy (along with diffusion MRI measures) 170 . Resting state motor networks were shown to be altered in both unilateral and bilateral CP, with greater change in the non-dominant hemisphere in unilateral CP 171 . Perfusion MRI was also used to show that regions with diffusion MRI changes demonstrate reduced perfusion 189 .…”

“…One study demonstrated increased MD in the dominant CST in unilateral CP 172 . In bilateral CP, one study also demonstrated bilateral reduced CST streamline count 176 , and another study demonstrated that FA and MD changes are more pronounced on the "more affected" side 171 . One study looked at children with dystonia, and showed no difference in FA of the CST from controls 177 .…”

“…Here we have identified a further 22 studies assessing the CST (results of studies in the previous review are not discussed here). In unilateral CP ten studies showed significantly reduced FA in the non-dominant CST 108-110, 112, 114, 169-173 ; eight studies also demonstrated increased MD 108,109,112,[169][170][171][172]174 ; five studies demonstrated reduced streamline count 109,112,169,171,174 ; one study demonstrated reduced volume and cross sectional area 175 , and one study demonstrated a change in Apparent Fibre Density (a metric derived from constrained spherical deconvolution) 112 . One study demonstrated increased MD in the dominant CST in unilateral CP 172 .…”

“…The superior thalamic radiations (the connection between thalamus and motor cortex) have been shown to exhibit reduced FA, increased MD as well as axial and radial diffusivity in both the non-dominant side of unilateral CP 95,110,171,172 and bilateral CP (contralateral to "more affected" limb) 171 . One study also demonstrated increased MD in the dominant hemisphere in unilateral spastic CP 172 .…”

“…This has been used in conjunction with structural connectivity measured by diffusion MRI 114,182 . This technique can be used to give an index of laterality 170,171,174 . Laterality indices were shown to correlate with FA in the posterior limb of the internal capsule 174 as well as improve with constraint induced movement therapy (along with diffusion MRI measures) 170 .…”