The somatosensory cortical activity in individuals with cerebral palsy displays an aberrant developmental trajectory

Abstract

Individuals with cerebral palsy (CP) have a reduced somatosensory cortical response Somatosensory cortical response strength decreases from adolescence to early adulthood Somatosensory cortical responses in youth with CP are similar to adult controls Individuals with CP may have aberrant maturation of the somatosensory system ABSTRACT: Numerous studies have documented tactile and proprioceptive deficits in children with cerebral palsy (CP) and linked these with weaker somatosensory cortical activity. However, whether such aberrations in somatosensory processing extend and/or progress into adulthood remains poorly understood. In the current study, we used magnetoencephalography (MEG) to investigate the primary somatosensory responses in a sample of individuals with CP (N = 42; age = 9-28 years) and a cohort of healthy controls (N = 23; age range = 11-23 years). Briefly, transient electrical stimulation was applied to the right tibial nerve, and standardized low-resolution brain electromagnetic tomography (sLORETA) was used to image the dynamic somatosensory cortical response. We found that the strength of somatosensory cortical activity within the 112-252 ms time window was significantly reduced in the individuals with CP compared with the healthy controls (HC = 286.53 ± 30.51, 95% CI [226.74, 346.32]; CP = 208.30 ± 19.66,CI [169.77, 246.83], P = 0.0126). These results corroborate previous findings of aberrant somatosensory cortical activity in individuals with CP. Our results also suggest that the somatosensory cortical activity tends to become weaker with age, with a similar rate of neurophysiological change in individuals with CP and healthy controls (P = 0.8790). Visualization of regression models fitted to the data imply that youth with CP may have somatosensory cortical activity similar to adult controls. These findings suggest that some individuals with CP exhibit an aberrant developmental trajectory of their somatosensory system.

Keywords: lower extremity; magnetoencephalography; sLORETA extremity; sensorimotor.

Figure 1:

Group averaged sLORETA images across the time window identified through cluster based permutation testing of the sensor level results (112 – 252ms) for the healthy controls (A) and individuals with CP (B). All responses were located in the leg region of the somatosensory cortex contralateral (left) to stimulation. Note that the units are arbitrary, and the threshold is lower for the group with CP in order to visualize the response.

Figure 2:

Left: Peak voxel time series. The stimulus was administered at time 0.0 ms (black line). The main somatosensory response, depicted in arbitrary units (AU), begins around 40 ms and diverges group-wise shortly thereafter. The time bin containing significantly different activity relative to baseline, which was subsequently used for further imaging analysis, is demarcated by the gray box (112 – 252 ms). Blue depicts the healthy controls and red depicts the individuals with cerebral palsy. The somatosensory response was notably weaker in the individuals with cerebral palsy. Right: Bar graph representing the difference in magnitude of the response between the healthy controls and the individuals with CP. The healthy controls had a significantly stronger response than the individuals with CP (P = 0.0126).

Figure 3:

There were parallel age related declines in somatosensory cortical activity between controls (blue) and individuals with CP (red). Inspection of linear regression models fit to the log transformed data of the respective groups conveyed that the slopes were relatively similar between the respective groups, but the intercept was shifted downward for the individuals with CP. The shifted intercept reflects the weaker somatosensory cortical activity seen in the individuals with CP across the examined age range. Inspection of the respective models indicates that the youth with CP exhibited somatosensory cortical activity that was similar to much older controls. This suggests that some of those with CP exhibit accelerated aging in the somatosensory system.