Reorganization of the somatosensory cortex in hemiplegic cerebral palsy associated with impaired sensory tracts

Abstract

Functional neuroimaging studies argue that sensory deficits in hemiplegic cerebral palsy (HCP) are related to deviant somatosensory processing in the ipsilesional primary somatosensory cortex (S1). A separate body of structural neuroimaging literature argues that these deficits are due to structural damage of the ascending sensory tracts (AST). The relationship between the functional and structural integrity of the somatosensory system and the sensory performance is largely unknown in HCP. To address this relationship, we combined findings from magnetoencephalography (MEG) and probabilistic diffusion tractography (PDT) in 10 children with HCP and 13 typically developing (TD) children. With MEG, we mapped the functionally active regions in the contralateral S1 during tactile stimulation of the thumb, middle, and little fingers of both hands. Using these MEG-defined functional active regions as regions of interest for PDT, we estimated the diffusion parameters of the AST. Somatosensory function was assessed via two-point discrimination tests. Our MEG data showed: (i) an abnormal somatotopic organization in all children with HCP in either one or both of their hemispheres; (ii) longer Euclidean distances between the digit maps in the S1 of children with HCP compared to TD children; (iii) suppressed gamma responses at early latencies for both hemispheres of children with HCP; and (iv) a positive correlation between the Euclidean distances and the sensory tests for the more affected hemisphere of children with HCP. Our MEG-guided PDT data showed: (i) higher mean and radian diffusivity of the AST in children with HCP; (ii) a positive correlation between the axial diffusivity of the AST with the sensory tests for the more affected hemisphere; and (iii) a negative correlation between the gamma power change and the AD of the AST for the MA hemisphere. Our findings associate for the first time bilateral cortical functional reorganization in the S1 of HCP children with abnormalities in the structural integrity of the AST, and correlate these abnormalities with behaviorally-assessed sensory deficits.

Foot and Ankle Somatosensory Deficits Affect Balance and Motor Function in Children With Cerebral Palsy

“…mechanism, which allows the correction of performance errors during the execution of a motor plan (Ghez, 1991;Schmidt and Lee, 2011); therefore, impairments in this system may impact motor behavior. In support of prior imaging work (Burton et al, 2009;Kurz et al, 2014aKurz et al, ,b, 2015Papadelis et al, 2014Papadelis et al, , 2018, our clinical findings suggested that sensory processing dysfunction is partially contributed to the motor planning and execution impairments that affect postural control and motor function in CP. Specifically, we provided evidence that somatosensory deficits in the LEs, especially two-point discrimination and cutaneous vibration sensation, appear to strongly influence balance and motor performance in children with spastic diplegia.…”

“…Furthermore, we acknowledge the fact that musculoskeletal deficits, along with poor somatosensory ability, can contribute to the noted motor impairments witnessed in children with CP as this pathology is multifactorial. Finally, over the course of the past decade, neuroimaging evidence has supported the existence of somatosensory processing deficits and abnormal sensorimotor connectivity in this population (Burton et al, 2009;Kurz et al, 2014aKurz et al, ,b, 2015Papadelis et al, 2014Papadelis et al, , 2018, however, there is limited research on the clinically detectable LE somatosensory impairments. Combining brain-imaging techniques with our clinical assessment methods may have further strengthened the results of this study.…”

“…Sensory deficits in CP have been primarily attributed to the injury of the immature brain and, secondarily, stem as a result of limited learning experience (Clayton et al, 2003;Rosenbaum et al, 2007) because motor impairments may not allow environmental exploration; a crucial element in development. Numerous imaging studies showed thalamocortical pathway disruption and aberrant somatosensory cortical activation in children with spastic CP (Burton et al, 2009;Kurz et al, 2014aKurz et al, ,b, 2015Papadelis et al, 2014Papadelis et al, , 2018, suggesting sensory processing dysfunction. Further, evidence demonstrated that the desynchronization of neuronal discharges in the somatosensory cortex has been related to the amount of error in ankle force performance (Kurz et al, 2014b), indicating that impaired feedback mechanisms can affect the skeletal musculature's ability of persons with CP to adapt in a changing environment.…”

Functional and structural asymmetry in primary motor cortex in Asperger syndrome: a navigated TMS and imaging study

“…Motor functions located partly in sensory cortex can reflect that the sensory cortex has taken over functions of motor cortex, or it can be related to impaired sensorimotor integration. Somewhat similar findings have been observed in hemiplegic cerebral palsy where abnormal somatotopic organization of functional primary sensory cortex to the precentral sulcus was observed (Papadelis et al 2018 ). This finding of functional reorganization was also associated with a structural finding using diffusion tractography, pointing out the importance of multimodal imaging, and also correlated with behaviorally-assessed sensory deficits.…”

Mapping the human brain during a specific Vojta's tactile input

“…[ 5 – 8 ] As future research in order to understand deeply these mechanisms, we propose the tractography analysis in conjunction with fMRI in patients with cerebral palsy during Vojta stimulation. [ 27 ]…”