Cold and mechanical allodynia in both hindpaws and tail following thoracic spinal cord hemisection in rats: time courses and their correlates.

We assessed (1) the time courses of cold and mechanical allodynia in both hindpaws and the tail, and (2) the relationship of the allodynia signs between different sites following spinal cord hemisection. Under enflurane anesthesia, rats were subjected to spinal hemisection at T13. The hemisected rats exhibited a significant increase in mechanical and cold allodynia signs of both hindpaws and the tail for 22-26 weeks postoperatively. In addition, mechanical allodynia signs were significantly correlated not only between the ipsilateral and the contralateral hindpaws, but also between the hindpaws and the tail. These results suggested that cold and mechanical allodynia developed extensively and lasted for a long time following spinal cord hemisection, and mechanical allodynia shown at different sites may be induced at least in part by common generating mechanisms.