 Inclusion Criteria:Severe pain in a lower extremity greater than 610 of duration more than 6 months despite aggressive previous therapy including both previous lumbar sympathetic block, and previous trial of at least 4 different pain medications including at least 2 of the following: gabapentin, amitryptiline, desipramine, nortryptiline, imipramine, carbamazepine, valproic acid, mexiletine, oxcarbazepine, topiramate, lamotrigine, flecainide, zonisamide, venlafaxine and levetiracetam. 