Changes in forelimb-hindlimb coordination after partial spinal lesions of different extent in the rat

Forelimb-hindlimb coordination in adult rats moving freely along 2m long runway was investigated using the method of footprint recording. Rats were divided into 3 groups with different extent of spinal lesions (T(9)). Before surgery rats moved with a mean locomotor speed of 73±20 to 96±18cms(-1), stride lengths of 17.5±2.0 to 21.2±2.0cm, and trot like coordination. Early after surgery the locomotor speed and the stride lengths were decreased. The forelimb steps were shorter than hindlimb steps, which led to the occurrence of unpaired forelimb steps. Unpaired steps occurred when the hind paw print lay more than half the hindlimb stride length in front of the ipsilateral paw. The number of unpaired steps was negatively correlated with the difference between the fore- and hindlimb step lengths. The recovery of locomotor speed, stride length, and step sequence patterns took up to 3.5 months depending on the extent of lesion. In the last testings the coordination was characterized by increased distances between ipsilateral footprints leading to a change from an almost synchronized trot to a lesion-dependent walk. This change was accompanied by a switch from the use of both patterns A and C to the most frequent use of the Aa pattern that is better adapted to maintain the body balance. All locomotor changes depended on the extent of the injury of lateral and ventral funiculi. These results demonstrate that footprint analysis can be used for the evaluation of forelimb-hindlimb coordination after spinal lesion in rats.