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

Objective: To evaluate the effect of nerve decompression on pain in patients with lower extremity painful diabetic peripheral neuropathy (DPN). Background: Currently, no treatment provides lasting relief for patients with DPN. The benefits of nerve decompression remain inconclusive. Methods: This double-blinded, observation and same-patient sham surgery-controlled randomized trial enrolled patients aged 18 to 80 years with lower extremity painful DPN who failed 1 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 the 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 the 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=m 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). The mean pain score was lower in decompressed versus sham legs (mean difference: 1.57 95% CI: 0.46 to 2.67; P=0.0002). Conclusions: Although nerve decompression was associated with reduced pain, the benefit of surgical decompression needs further investigation as a placebo effect may be responsible for part or all of these effects.