American Society for Peripheral Nerve

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The DNND (Diabetic Neuropathy Nerve Decompression) Study: A Controlled Randomized Double Blinded Prospective Study on The Effect Lower Extremity Nerve Decompression on Pain and Quality of Life in Patients with Painful Diabetic Neuropathy
Shai Michael Rozen, MD1; Gil Wolfe, MD2; Philip Raskin, MD1; Steven Vernino, MD1; Geetha Pandian, MD1; Kathleen Wyne, MD3; Shiv Sharma, MD1; Joan Reisch, PhD1; Linda Hynan, PhD1; Rita Fulmer, RN1; Annamaria Salvadore, BS1
1University of Texas Southwestern Medical Center, Dallas, TX, 2University of Buffallo, Buffalo, NY 3The Ohio State University Wexner Medical Center, Columbus, OH

Purpose: An estimated fifty-percent of 74.8 million pre-and diabetic patients in the USA suffer from Painful Diabetic Neuropathy (PDN), of which approximately one-third are prone to nerve compression. Previous studies suggest surgical decompression alleviates pain, however the American Neurological Association considers available evidence level U (Unproven). We present a seven-year NIH and institutionally funded, prospective, controlled, randomized double-blinded study to determine the long-term effect of nerve decompression in patients with PDN on pain and quality of life.

Methods: A multidisciplinary neurology, endocrinology, PM&R, pain, and surgery group performed baseline pain examinations (Likert 0-10, Neuropathy-scores) and SF-36 quality of life exams. Patients were randomized into surgical and non-surgical-control groups (2:1 ratio, respectively). Surgical patients underwent surgery bilaterally with each side randomized to nerve decompression or sham surgery. Patient and final evaluators were blinded to side. Quarterly, final one-year, and four-year evaluations were performed. A 2 way repeated measures ANOVA statistical analysis on pain was performed on all groups at one year and 54.5 month follow-up.

Results: Of 2987-screened patients, 138 enrolled: 92 randomized to surgery and 46 as controls. 40 surgical and 27 controls completed the study. At one year the surgical group experienced a mean pain reduction of 5.70 in the surgical leg (SD=2.54;p<0.0001) and 5.25 (SD=2.79;p<0.0001) in the sham leg while the control group had no statistically significant reduction of pain. A 54.5-month follow-up of 36 surgical patients revealed a mean pain reduction of 7.47 in the surgical leg (SD=2.09;p<0.0001) and 5.97 (SD=2.43;p<0.0001) in the sham leg, while the control group revealed no reduction in pain. The SF-36 General Health component score revealed a significant interaction for group by time, p=.0010; while group means at baseline, 3mo, and 6months (p=0.53, 0.24, and 0.10, respectively) were not significantly different, means at 9 months and 1 year were significant (p=0.01 and 0.02, respectively).

Conclusion: Surgical decompression in patients with PDN unequivocally reduces bilateral pain with statistical significance at one year and continued bilateral improvement at four years, yet demonstrates more statistically significant pain reduction in the decompressed side at four years. In addition, quality of life is significantly improved at 1-year follow up.

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