Effect of Lower Extremity Nerve Decompression in Patients with Painful Diabetic Peripheral Neuropathy: The DNND Randomized, Observation Group- and Placebo Surgery-controlled Clinical Trial.

OBJECTIVE:Evaluate the effect of nerve decompression on pain in patients with lower extremity painful Diabetic Peripheral Neuropathy (DPN). SUMMARY BACKGROUND DATA:Currently, no treatment provides lasting relief for patients with DPN. Benefits of nerve decompression remain inconclusive. METHODS:This double-blinded, observation- and same-patient sham surgery-controlled randomized trial enrolled patients aged 18-80 years with lower extremity painful DPN who failed one-year of medical treatment. Patients were randomized to nerve decompression- or observation-group (2:1). Decompression-group patients were further randomized and blinded to nerve decompression in either right or left leg and sham surgery in the opposite leg. Pain (11-point Likert score) was compared between decompression and observation groups and between decompressed versus sham legs at 12 and 56 months. RESULTS:Of 2987 screened patients, 78 were randomized. At 12 months, compared with controls (n=37), both right-decompression-group (n=22) and left-decompression-group (n=18) reported lower pain (mean difference for both, -4.46; [95% CI, -6.34 to -2.58 and -6.48 to -2.45 respectively]; P<0.0001). Decompressed and sham legs equally improved. At 56 months, compared with controls (n=14), pain was lower in both the right-decompression-group (n=20) (mean difference, -7.65; [95% CI, -9.87 to -5.44]; P<0.0001) and left-decompression-group (n=16) (mean difference, -7.26; [95% CI, -9.60 to -4.91]; P<0.0001). Mean pain score was lower in decompressed versus sham legs (mean difference, 1.57 [95% CI, 0.46 to 2.67]; P=0.0002). CONCLUSION:Although nerve decompression was associated with reduced pain, the benefit of surgical decompression needs further investigation since a placebo effect may be responsible for part or all of these effects.