Functional near-infrared spectroscopy to assess sensorimotor cortical activity during hand squeezing and ankle dorsiflexion in individuals with and without bilateral and unilateral cerebral palsy

Abstract

Significance: Our study is the first comparison of brain activation patterns during motor tasks across unilateral cerebral palsy (UCP), bilateral cerebral palsy (BCP), and typical development (TD) to elucidate neural mechanisms and inform rehabilitation strategies. Aim: Cortical activation patterns were compared for distal upper and lower extremity tasks in UCP, BCP, and TD using functional near-infrared spectroscopy (fNIRS) and related to functional severity. Approach: Individuals with UCP ( $n=10$ , $18.8\pm 6.8\text{years}$ ), BCP ( $n=14$ , $17.5\pm 9.6\text{years}$ ), and TD ( $n=16$ , $17.3\pm 9.1\text{years}$ ) participated in this cross-sectional cohort study. The fNIRS was used to noninvasively monitor the hemodynamic response to task-related cortical activation. The block design involved repetitive nondominant hand squeezing and ankle dorsiflexion. Results: Individuals with UCP demonstrated the highest levels of activation for the squeeze task ( $\mathrm{UCP}>\mathrm{BCP}$ $q=0.049$ ; $\mathrm{BCP}>\mathrm{TD}$ $q<0.001$ ; and $\mathrm{UCP}>\mathrm{TD}$ $q=0.001$ ) and more activity in the ipsilateral versus contralateral hemisphere. Individuals with BCP showed the highest levels of cortical activation in the dorsiflexion task ( $\mathrm{BCP}>\mathrm{UCP}$ $q<0.001$ ; $\mathrm{BCP}>\mathrm{TD}$ ). Conclusions: Grouping by CP subtype and manual function or mobility level demonstrated significant differences from TD, even for individuals with the mildest forms of CP. Hemispheric activation patterns showed hypothesized but nonsignificant trends.

Keywords: brain imaging; cerebral palsy; diplegia; functional near-infrared spectroscopy; hemiplegia; motor control.