Pediatric slow-progressive cerebellar atrophy (but not non-progressive hypoplasia) delays intra-limb anticipatory postural adjustments

Cerebellum is known to time both voluntary actions and the related postural activities. We recently investigated its role during human development (doi:10.3390/app10051606), reporting that children affected by a slow-progressive cerebellar atrophy (SlowP) show worse postural control during standing and delayed postural actions in gait initiation, compared to healthy children (H). Instead, children suffering non-progressive hypoplasia (NonP) behaved similarly to H. We proposed that such difference stems from the establishment of compensatory networks in NonP children, which instead conflicts with the disease progression in SlowP. To extend our findings to intra-limb postural control, we recorded the Anticipatory Postural Adjustments (APAs) developing in the arm, and stabilizing it, when briskly flexing the index-finger. Ten SlowP, NonP and H children were enrolled. Again, no significant timing differences occurred between NonP and H. Instead in SlowP the excitatory APAs in Triceps Brachii were significantly delayed (~40 ms) in all 10 children, while in 5 children the inhibitory APAs - normally occurring in Biceps Brachii and Anterior Deltoid prior to a late excitation - were delayed of 40-60 ms. In the other 5, such APAs were lacking as if the delayed inhibition slipped under the late excitation. These results reinforce the idea that the NonP brain is free to build-up a compensatory network which does not suffer from the disturbing effects of the disease progression.