Fig. 2. Intrathecal lidocaine injection reversed well-established tactile allodynia caused by sciatic nerve ligation (SNL). Four weeks after SNL, the withdrawal threshold of the ipsilateral (IPSI) hind paw was significantly decreased compared with the prelesion baseline (A –C , *P < 0.05). The value in the contralateral (CONTRA) hind paw was not significantly different from the prelesion baseline at all time points tested. Two hours, 1 and 2 days after 100 (A ), 200 (B ), and 300 μg (C ) intrathecal lidocaine injection, the withdrawal threshold in the ipsilateral hind paw was reversed to the prelesion level. Three days after injection, the value in the ipsilateral hind paw in SNL rats receiving 200 (B ) and 300 μg (C ) lidocaine returned to a level that was significantly lower than the prelesion baseline (*P < 0.05). However, the value in the contralateral hind paw of SNL rats intrathecally injected with 100 μg lidocaine still remained elevated (A ). Four days after injection, the withdrawal threshold in the ipsilateral hind paw of all lidocaine-injected rats was significantly lower than the prelesion baseline (A –C , *P < 0.05). Mean ± SEM, n = 4–5 in each group.