5.28 The role of strategic changes in plastic adaptation oflocomotor function (original) (raw)

Chapter 5. Multi-sensory integration 33 normal subjects and 80 subacute patients with a first hemisphere stroke (54 left, 26 right). On the basis of the Scale for Contraversive Pushing (SCP) (Karnath et al., 2000), 45 were considered as upright in sitting and standing, and 35 showed a contralesional lateropulsion. Among these latter 6 showed a contralesional lateropulsion plus pushing. The four groups of subjects were compared: normals, upright patients, patients with lateropulsion but no pushing, pushers. Results: No patient showed an ipsilesional HV or PV tilt whereas 9% showed an abnormal ipsilesional W tilt, of mild magnitude. An abnormal contralesional tilt was found: in 55% for VV, 42% for PV, and 32.5% for HV A marked difference between groups was found. VV, HV, and PV were more tilted in pushers than in all other groups, more tilted in patients showing lateropulsion without pushing than in upright patients and normals, and also more tilted in upright patients than in normals (although their orientation were inside ranges of normality). In pushers PV was more tilted than VV and HV whereas these three modalities did not differ in other groups. In order to further understand how much verticality perception indices could explain the lateropulsion/pushing behaviour, we performed a variable selection. The variable which best explained the SCP was PV, which alone accounted for 51% of the information contained in SCP variations. Discussion: The contralesional lateropulsion frequently observed after a hemisphere stroke seems due to a contralesional tilt in the postural perception of the vertical, patients aligning their erect posture on this erroneous referential. Beyond stroke, this study shows how perception and action with respect to gravity are closely related.