Spatial cognition in young children with spinal muscular atrophy

Success in visuospatial tasks has often been demonstrated in teenagers with spinal muscular atrophy (SMA). However, what has been tested in these studies, with the Wechsler Intelligence Scale for Children-Revised (Wechsler, 1974) performance scale, does not deal with the spatial capacities that co-occur with the advent of self-produced locomotion. Indeed, various studies have shown that occurrence of locomotion in infancy is correlated with the development of visuospatial cognitive competencies, suggesting that locomotor experience might play a central role in spatial development, especially in the realm of manual search for hidden objects. It is thus of interest to assess spatial search skills in SMA young children suffering total deprivation of locomotor experience. Twelve Type-2 SMA children with a mean age of 30 months were compared with controls with respect to their spatial search skills in a memory-for-locations task. In this search task, hiding containers were rotated 180 degrees before search was permitted. The performance obtained with the SMA group did not differ from that obtained in the healthy control group. SMA patients searched correctly for a hidden object in the 3-choice search task. Locomotor impairment does not appear to be a key risk factor for dramatic slowing down or deviation in the development of spatial search skills, as assumed by some authors. Further research is needed to identify the alternative pathways to normal spatial development that are used by SMA young children.