Somatosensory-evoked cortical activity in spastic diplegic cerebral palsy

Somatosensory deficits have been identified in cerebral palsy (CP), but associated cortical brain activity in CP remains poorly understood. Functional MRI was used to measure blood oxygenation level-dependent (BOLD) responses during three tactile tasks in 10 participants with spastic diplegia (mean age: 18.70 years, SD: 7.99 years; 5 females) and 10 age-matched controls (mean age: 18.60 years, SD: 3.86 years; 5 females). Tactile stimulation involved servo-controlled translation of smooth or embossed surfaces across the right index finger pad; the discrimination tasks with embossed surfaces involved judging whether (1) paired shapes were similar or different, and (2) a rougher set of horizontal gratings preceded or followed a smoother one. Velocity and duration of surface translation was identical across all trials. In addition, an event-related design revealed response dynamics per trial in both groups. Compared to controls, individuals with spastic diplegia had significantly reduced spatial extents in activated cortical areas and smaller BOLD response magnitudes in cortical areas for somatosensation, motor, and goal-directed/attention behaviors. These results provide mechanisms for the widespread somatosensory deficits in CP. The reduced activation noted across multiple cortical areas might contribute to motor deficits in CP.