SLR - November 2014 - Christopher P. Tveter

Value of Surgical Decompression of Compressed Nerves in the Lower Extremity in Patients with Painful Diabetic Neuropathy: A Randomized Controlled Trial

Reference: Macaré van Maurik, JFM, et al. Value of Surgical Decompression of Compressed Nerves in the Lower Extremity in Patients with Painful Diabetic Neuropathy: A Randomized Controlled Trial. Plast Reconstr Surg. 2014 Aug;(2):325-32.

Scientific Literature Review

Reviewed By: Christopher P. Tveter, DPM
Residency Program: Steward - St. Elizabeth’s Medical Center

Podiatric Relevance: Painful diabetic neuropathy is a complication of diabetes mellitus commonly seen in the podiatric office. Surgical decompression of peripheral nerves has been previously described in the literature as a treatment for this condition. This study sought to perform a randomized control trial to assess its value in providing pain relief and restoration of peripheral sensation.

Methods: This study was conducted as a single-center randomized controlled trial with one surgical intervention and one-year follow-up. Between 2010 and 2013, forty-two patients previously diagnosed with painful bilateral diabetic polyneuropathy were included. Inclusion criteria were a positive Tinel sign at one or more of the following locations: the tibial, superficial, or common peroneal nerve; ankle-brachial index of 0.7 or greater; and palpable pulses in the posterior tibial artery and dorsal pedal artery. Exclusion criteria were BMI > 35 kg/m2, a general condition unsuitable for surgery, a history of ankle fractures or amputations proximal to the Lisfranc joint, ulcer on the foot, sufficient effect of pain medications (visual analog scale (VAS) score of 0-1), other causes of neuropathy, and indications for and history of nerve compression at additional sites. Each patient underwent a decompression in one limb of the tibial, common peroneal, deep peroneal, and superficial peroneal nerves as described by Dellon. A Web-based randomization system was used to choose the leg that would receive intervention. The contralateral limb was used as a control. The surgical procedure consisted of four incisions: at the medial ankle to release the tibial nerve, at the anterior ankle to release the deep peroneal nerve under the extensor hallucis brevis, 10-14cm proximal to the lateral malleolus to release the superficial peroneal nerve, and dorsolateral to the fibular neck to release the common peroneal nerve. Post-operatively, patients were instructed to actively flex and extend the ankle for 2.5 weeks while ambulating as tolerated. Evaluation of pain was assessed using the VAS score for both legs separately, filled out by patients preoperatively and at 3, 6, and 12 months postoperatively. Tactile sensation was assessed using a 5.07 Semmes Weinstein monofilament, as well as two-point discrimination using the Dellon Disk-Criminator. Both were evaluated at nine designated points along the plantar foot. Statistical differences were calculated using analysis of variance repeated measures with Bonferroni correction and two-tailed Student’s t tests.

Results: Forty-two patients were included in this study. One patient died during the follow-up period from unrelated circumstances. One patient was lost to follow-up, and two patients were not evaluated at three months and were excluded from statistical analysis. Of the remaining 38 patients, there were three complications. One was a hematoma that required an additional operation. Two patients also had wound infections at ankle sites, treated with antibiotics.

VAS: Preoperatively, there was no significant difference between the mean VAS scores in the control and intervention legs (both 6.1). At three months postoperatively, a significant decrease in scores was noted in both intervention and control legs when compared to pre-operative scores (2.8 and 4.4, respectively). This continued throughout the postoperative course, although these scores began regressing towards their pre-operative scores at 12 months (3.5 and 5.3, respectively). Significant differences between intervention and control legs were continued throughout the postoperative course.  

Semmes Weinstein Monofilament: Preoperative scores were not significant between control and intervention legs. At three months postoperatively, the intervention leg score significantly increased from control and baseline scores, however this score decreased at 12 months and was not significantly significant from the control leg and baseline scores.

Two-Point Discrimination: Preoperative scores were not significant between control and intervention legs. After 12 months, the comparison between the intervention and control legs revealed no significant improvement in the ability to distinguish between two points.

Conclusion: This randomized, controlled trial demonstrates the short-term improvements in pain relief following surgical decompression of nerves in patients with painful diabetic neuropathy. It is interesting to note that pain relief was noted in the control leg in addition to the intervention leg. Evaluation of tactile sensation using Semmes Weinstein Monofilament and two-point discrimination test did not find improvement at the 12 weeks post-operatively. Additional studies evaluating more long-term follow-up are warranted.

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