[Prospective study of prevalence and risk factors for painful phantom limb in the immediate postoperative period of patients undergoing amputation for chronic arterial ischemia].

OBJECTIVE

To determine the prevalence and risk factors associated with postoperative phantom limb pain (PLP) in patients amputated for chronic ischemia of a lower limb.

PATIENTS AND METHOD: Prospective, longitudinal, epidemiological study of patients amputated for chronic grade IV ischemia. PLP, defined as the perception of pain > or = 3 on a verbal scale of 0 to 10, was assessed in the first week after surgery. Candidate risk factors analyzed were patient characteristics, course of ischemic disease, and features of surgery or anesthetic technique.

RESULTS

The prevalence of PLP was 26% (14 patients) in a total of 53 amputations performed on the same number of patients over one year. Mean patient age was 68.4 +/- 11.2 years, and 45 (84.9%) were diabetics. Phantom limbs were felt by 9 patients (17%), and a painful stump was reported by 5 (10%). The most common PLP symptoms were a burning sensation and painful paresthesia. Risk factors identified, in order of statistical significance, were prior amputation (p < 0.0002), oral antidiabetic therapy (p < 0.02) and type of amputation (p = 0.05). Logistic regression analysis of variables revealed increased risk of PLP in patients with a prior amputation (odds ratio [OR] 8.1) and those receiving oral antidiabetic therapy (OR 3.9). Insulin treatment was a protective factor (OR 0.5).

CONCLUSIONS

The prevalence of PLP among patients with chronic ischemia of the lower limb in our setting is considerable, although low in comparison to the prevalence reported for other settings. Identifying risk factors such as those described in this study helps to establish the profile of patients toward whom to direct measures to prevent PLP.