The role of the cerebellum in challenging postural control conditions

• ¹ KU Leuven, Movement Control and Neuroplasticity Group, Belgium
• ² University of Ghent, Department of Physical Therapy and Motor Rehabilitation, Belgium
• ³ Leuven Research Institute for Neuroscience & Disease (LIND), Belgium

Traumatic brain injury (TBI) patients often experience balance problems. These balance deficits are not always prominent in static conditions (e.g. standing still), they can be revealed in more challenging contexts (e.g. unstable surface, dual task). The cerebellum has been implicated in postural control and also plays a role in coordinating and fine-tuning movements, which become increasingly important with higher degrees of task complexity. The aim of this study was to investigate to which extent grey matter (GM) atrophy of the cerebellum in TBI contributes to balance deficits, and to map in which subregions of the cerebellum GM volume relates to complex postural control. Young TBI patients (N=19, 14.0y, 10 male) and controls (N=30, 14.8y, 13 male) performed three tasks on the EquiTest® system (Neurocom). The sensory organization test (SOT) decreases sensory input availability, the rhythmic weight shift (RWS) and limits of stability (LOS) test require intentional centre of gravity shifts to target locations. Clusters of GM volume associated with balance control were identified in a cerebellum-optimized voxel based morphometry (VBM) analysis using the SUIT toolbox (Diedrichsen, 2006), controlling for total intracranial volume and age. The centre of pressure trajectory revealed that the TBI patients exhibited lower postural stability during the SOT (p<0.05) and RWS (p<0.05) task, but performed rather well on the LOS task (p>0.10). Compared to the controls GM volume in the anterior cerebellum was reduced in the TBI group (ROI, p<.05, FDR corr). Within the TBI group, volume of the anterior cerebellum related to performance on the LOS (lobule V, p<.05, FDR corr). Within the total group, performance on the SOT and LOS related to GM volume of the (para)vermis of lobule VIII. RWS related to GM volume of lobule V and (para)vermis of lobule VI (p<.05, FDR corr). These subregions of the cerebellum have all been implicated in sensorimotor integration during overt movement (Stoodley et al., 2012). Our results suggest they also play an important role in the control of complex postural tasks, and that GM atrophy of these cerebellar subregions mediates balance deficits in TBI.