Dynamic Motor Function Following Concussion

Abstract

The need to identify functional impairment following a brain injury is critical to prevent re-injury during the period of recovery. Research to date has focused on neuropsychological tests and static postural control during quiet standing. However, little is known about the effect of concussion on dynamic motor function. PURPOSE The purpose of this study was to examine the effect of concussion on a dynamic motor task under conditions of divided and undivided attention. METHODS Fifteen subjects with Grade 2 concussions (CONC) and 15 uninjured controls (NORM) were observed while walking under two conditions:1) undivided attention (single-task) and 2) while simultaneously completing simple mental tasks (dual-task). For the CONCs the protocol began within 48 hours of injury (day 2) and repeated at 5, 14, and 28 days post injury. The NORMs were also evaluated at the same time intervals. Whole-body motion data were collected using a six-camera motion analysis system and two force plates to examine anterior and medial-lateral COM motion (APROM, MLROM), anterior velocity of the COM (ANTVEL), and the maximum separation between the COM and COP (APMAX). Three-way repeated-measures mixed design ANOVA and Tukey post hoc tests were completed to determine differences between group, task, and testing day (p <.05). RESULTS There were significant group interactions with day for MLROM, (p <.02), APVEL, (p <.02), and APMAX (p <.00). A significant task by group interaction was found for APROM (p <.03). Follow-up analyses revealed significantly decreased dual-task APROM for CONCs compared to NORMs at all 4 days. CONCs also displayed decreased ANTVEL and APMAX at days 2, 14, and 28.Medial-lateral sway was significantly increased at days 2, 5, and 28 for CONCs compared to NORMs. CONCLUSIONS Concussed individuals continue to display significant differences in anterior velocity and COM movement when compared to uninjured controls up to four weeks after injury. Maintenance of balance and limb coordination during locomotion or sport activities requires a complex interaction of sensory input and motor output. The findings of this study demonstrate that concussion has an observable and measurable effect on the body's ability to maintain and control dynamic stability. This study was supported by the Centers for Disease Control and Prevention (R49/CCR021735 and CCR023203).