fMRI analysis of ankle movement tracking training in subject with stroke

This study examined whether ankle-movement tracking training could improve ankle function and brain reorganization, evidenced with functional magnetic resonance imagery (fMRI), in a single subject with stroke. Test measurements included self-ratings of functional activities, 15.24 m (50 feet) walk time, ankle range of motion, ankle tracking accuracy, and peak dorsiflexion movement during dorsiflexion phases of tracking. Cortical activation in the frontal and parietal lobes was measured during fMRI with an active voxel count. Additionally, a signal intensity index was determined for the gyrus precentralis (GPrC). Training consisted of 16 sessions of tracking waveforms on a computer screen with ankle motion. Four pretest, four posttest and two follow-up measurements occurred. Data were analyzed by visual inspection and by statistical analysis that examined whether posttest measurements exceeded the pretest mean by at least two standard deviations on at least two consecutive posttest measurements. Posttest results showed that the subject's self report of paretic ankle "catches" (failure of toes to clear floor during swing phase) during gait were eliminated and that peak dorsiflexion movement improved visually but not statistically. Multiple cortical areas showed increased voxel count statistically, as did the intensity index for GPrC. Follow-up results showed that the ankle "catches", peak dorsiflexion movement, and the intensity index remained at the same levels as posttest. Voxel counts returned toward pretest values. We concluded that tracking training produced training effects in both ankle function and brain reorganization.