Repeated lumbar sympathetic blockade with lidocaine and clonidine attenuates pain in complex regional pain syndrome type 1 patients--a report of two cases.

Repeated lumbar sympathetic blockade (LSB) with local anesthetics is generally used in complex regional pain syndrome (CRPS) of the lower extremities if the initial block has been successful. However, the symptoms of CRPS may inevitably recur in spite of repeated LSB. Clonidine, an alpha2-adrenoceptor agonist, has both anesthetic and analgesic sparing effects, and when added to local anesthetics may enhance peripheral and central neural block due to its local or central analgesic effects. It is reasonable that clonidine has been used in chronic pain conditions such as neuropathic and sympathetically maintained pain. Here we report two cases of CRPS type 1 who got excellent analgesia and alleviation of clinical symptoms after receiving an LSB with lidocaine and clonidine.