Brain Metabolism During A Lower Extremity Voluntary Movement Task in Children With Spastic Cerebral Palsy.

Daniel H. S. Silverman,Eileen G. Fowler,Shantanu H. Joshi,William L. Oppenheim,Marcia B. Greenberg,Loretta A. Staudt

doi:10.3389/fnhum.2020.00159

Abstract

Reduced selective voluntary motor control (SVMC) is a primary impairment due to corticospinal tract (CST) injury in spastic cerebral palsy (CP). There are few studies of brain metabolism in CP and none have examined brain metabolism during a motor task. Nine children with bilateral spastic CP [Age: 6-11 years, Gross Motor Function Classification System (GMFCS) Levels II–V] completed this study. SVMC was evaluated using Selective Control Assessment of the Lower Extremity (SCALE) ranging from 0 (absent) to 10 (normal). Brain metabolism was measured using positron emission tomography (PET) scanning in association with a selective ankle motor task. Whole brain activation maps as well as ROI averaged metabolic activity were correlated with SCALE scores. The contralateral sensorimotor and superior parietal cortex were positively correlated with SCALE scores (p < 0.0005). In contrast, a negative correlation of metabolic activity with SCALE was found in the cerebellum (p < 0.0005). Subsequent ROI analysis showed that both ipsilateral and contralateral cerebellar metabolism correlated with SCALE but the relationship for the ipsilateral cerebellum was stronger (R2 = 0.80, p < 0.001 vs. R2 = 0.46, p = 0.045). Decreased cortical and increased cerebellar activation in children with less SVMC may be related to task difficulty, activation of new motor learning paradigms in the cerebellum and potential engagement of alternative motor systems when CSTs are focally damaged. These results support SCALE as a clinical correlate of neurological impairment.

Highlights

Children with spastic cerebral palsy (CP) have developmental brain injuries primarily affecting the motor systems
While damage to the developing corticospinal tract (CST) is a primary etiology in spastic CP, resulting compensatory adaptations have not been adequately studied relative to brain structure and activity, especially for lower extremity function in patients with bilateral involvement
Motor impairment ranged from mild (GMFCS Level II, Gross Motor Function Measure (GMFM) 72.2, Selective Control Assessment of the Lower Extremity (SCALE) 7 bilaterally) to severe (GMFCS Level V, GMFM 36.0, SCALE scores ≤ 3)

Summary

Introduction

Children with spastic cerebral palsy (CP) have developmental brain injuries primarily affecting the motor systems. Impairments of motor control are observed early in development (Fetters et al, 2004; Sargent et al, 2017) often preceding the detection of spasticity in children with CP. Spastic CP results from damage to the periventricular white matter containing descending motor tracts including the corticospinal tracts (CSTs) responsible for voluntary motor control White matter damage including the CSTs has been described and quantified in CP and correlated with motor and sensory function measures using magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) techniques (Hoon et al, 2009; Lee et al, 2011). While damage to the developing CSTs is a primary etiology in spastic CP, resulting compensatory adaptations have not been adequately studied relative to brain structure and activity, especially for lower extremity function in patients with bilateral involvement

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