Lower Extremity Complex Regional Pain Syndrome: Long-term Outcome after Surgical Treatment of Peripheral Pain Generators

We undertook a retrospective study to evaluate the hypothesis that complex regional pain syndrome (CRPS) I, known as the "new" reflex sympathetic dystrophy, persists because of undiagnosed injured joint afferents, cutaneous neuromas, or nerve compressions, and is, therefore, a misdiagnosed form of CRPS II, which is known as the "new" causalgia. We used a research protocol, with institutional review board approval, to review medical records for the purpose of identifying 30 patients with lower extremity reflex sympathetic dystrophy, based on their history, physical examination, neurosensory testing, and response to peripheral nerve blocks, who were treated surgically at the level of the peripheral nerve. In this report, we describe long-term outcomes in 13 of these patients who were followed up for a minimum of 24 months (mean, 47.8 months; range, 25-90 months). Based primarily on the results of physical examination and the response to peripheral nerve blocks, surgery included a combination of joint denervation, neuroma resection plus muscle implantation, and neurolysis. Outcomes were measured in terms of decreased pain medication usage and recovery of function, and the results were excellent in 7 (55%), good in 4 (30%), and poor (failure) in 2 (15%) of the patients. Based on these results, we concluded that most patients referred with a diagnosis of CRPS I have continuing pain input from injured joint or cutaneous afferents, and chronic nerve compression, which is indistinguishable from CRPS II, and amenable to successful treatment by means of an appropriate peripheral nerve surgical strategy.