Article

In many children with unilateral spastic cerebral palsy (USCP), the
corticospinal tract to the affected hand atypically originates in the hemisphere
ipsilateral to the affected hand. Such ipsilateral connectivity is on average a
predictor of poor hand function. However, there is high variability in hand
function in these children, which might be explained by the complexity of motor
representations of both hands in the contralesional hemisphere. OBJECTIVE: To
measure the link between hand function and the size and excitability of motor
representations of both hands, and their overlap, in the contralesional
hemisphere of children with USCP. METHODS: We used single-pulse transcranial
magnetic stimulation to measure the size and excitability of motor
representations of both hands, and their overlap, in the contralesional
hemisphere of 50 children with USCP. We correlated these measures with manual
dexterity of the affected hand, bimanual performance, and mirror movement
strength. RESULTS: The main and novel findings were (1) the large overlap in
contralesional motor representations of the 2 hands and (2) the moderate positive
associations of the size and excitability of such shared-site representations
with hand function. Such functional associations were not present for overall
size and excitability of representations of the affected hand. CONCLUSIONS:
Greater relative overlap of the affected hand representation with the
less-affected hand representation within the contralesional hemisphere was
associated with better hand function. This association suggests that overlapping
representations might be adaptively "yoked," such that cortical control of the
child's less-affected hand supports that of the affected hand.

Langue : ANGLAIS