Fig. 4.

Time course of 50% withdrawal threshold to the graded von Frey filaments stimulation applied to the plantar surface of the hindpaw. The average paw withdrawal threshold before the contusion was approximately 15 g. However, following the contusion injury, the withdrawal thresholds to von Frey stimulation decreased markedly to 1.96 ± 0.35 g in the 6.25 mm group and 1.31 ± 0.16 g in the 12.5 mm group at 2 weeks PO and was slightly increased with the lapse of time. Asterisks (*) indicate the values significantly different from the pre-operative value. The time after the spinal cord contusion indicates weeks (W) following spinal contusion, except for "pre", which represents the preoperative test period.