A comprehensive analysis of gait impairment after experimental stroke and the therapeutic effect of environmental enrichment in rats.

Although gait changes are considered as reliable indices of stroke severity and efficacy of rehabilitative therapies in humans, data from animal models of focal ischemia are lacking. To determine the effect of stroke on gait function in adult rats with distal middle cerebral artery occlusion (MCAO), we assessed the longitudinal changes in gait using an automated computer-assisted gait analysis system. Four days after MCAO, intensity, maximal area of contact, and paw angle were significantly decreased in the affected forepaw whereas the double support time using ipsilateral paws increased. Relative print positions between the fore and hindpaws and limb coupling were also altered, suggesting that stroke affected sensorimotor status and reduced limb coordination. Except for paw angle, these impairments persisted for at least 5 weeks. However, unlike human stroke patients, stride length and stance were not affected in rats with MCAO. Environmental enrichment for 4 weeks improved paw contact area and relative print position of the affected limb and reduced double support time in ischemic rats compared with controls. Our results indicate that gait analysis provides great insight into various aspects of motor function changes in ischemic quadrupeds, and that environmental enrichment is beneficial in reducing a variety of poststroke gait impairments possibly through enhanced structural plasticity mechanisms within injured cortical neuronal networks underlying locomotor function.