Evaluation of five tests for the assessment of functional recovery following C4 or T7 dorsal column transection in the rat

The dorsal column lesion model of spinal cord injury targets sensory fibres which originate from the dorsal root ganglia and ascend in the dorsal funiculus. It has the advantages that fibres can be specifically traced from the sciatic nerve, verifiably complete lesions can be performed of the labelled component, and it can be used to study sprouting in the central nervous system from the conditioning lesion effect. However, functional deficits from this type of lesion are mild making assessment of experimental treatment-induced functional recovery difficult. Here, we compared a number of functional tests for their suitability to reliably measure recovery of function after dorsal column injury. We have examined the tape removal test, the rope crossing test, CatWalk™XT gait analysis, the horizontal ladder crossing test, and we introduce a new test, named the inclined rolling ladder. We compared animals with dorsal column injuries at C4 or T7 level to sham-operated animals for a duration of eight weeks. In most tests we were able to detect a significant deficit over the course of the experiment, although in most tests function recovered within 2-6 weeks. Cervical lesions showed more robust deficits than thoracic lesions. The horizontal ladder test showed the most statistically robust deficits. However the inclined rolling ladder showed promise as the functional deficits appeared to persist for 7 weeks and may prove useful to monitor the efficacy of treatments for this lesion model.