Fig. 4. (A ) Temporal changes in the mechanical sensitivity to von Frey filaments after spinal nerve ligation and effect of continuous intrathecal methylprednisolone on existing mechanical allodynia. Methylprednisolone significantly reversed mechanical allodynia, and this effect of persisted for at least 3 weeks. (B ) Temporal changes in the paw withdrawal latency to heat stimuli after spinal nerve ligation and effect of intrathecal methylprednisolone on existing thermal hyperalgesia. Methylprednisolone significantly reversed thermal hyperalgesia, and this effect persisted for at least 3 weeks. Bar  above the x-axis represents intrathecal treatment with methylprednisolone or saline. +P < 0.005, ++P < 0.0005, +++P < 0.0001 versus  saline.