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Alteration of Sciatic Nerve Histology and Electrical Function After Compression and After Neurolysis in a Diabetic Rat Model

Hu, Junda, MD*; Tu, Yiji, MD, PhD*; Ding, Zuoyou, MD*; Chen, Zenggan, MD, PhD*; Lee Dellon, A., MD, PhD, FACS; Lineaweaver, William C., MD, PhD, FACS; Zhang, Feng, MD, PhD*‡

doi: 10.1097/SAP.0000000000001646
Peripheral Nerve Surgery and Research

Background Diabetic rats are more sensitive to nerve entrapment. This study was conducted to evaluate nerve function and histological changes in diabetic rats after nerve compression and subsequent decompression.

Methods A total of 35 Wistar rats were included. The experimental group was divided into diabetic sciatic nerve compression group (DSNC, n = 5) and diabetic sciatic nerve decompression group (DSND, n = 20). The DSNC model was created by wrapping a silicone tube circumferentially around the nerve for 4 weeks, and then the DSND group accepted nerve decompression and was followed up to 12 weeks. The DSND group was equally divided into DSND 3 weeks (DSND3), 6 weeks (DSND6), 9 weeks (DSND9), and 12 weeks (DSND12) groups. Five rats were taken as normoglycemic control group (CR, n = 5), and another 5 rats as diabetic control group (DM, n = 5). The mechanical hyperalgesia of rats was detected by Semmes-Weinstein nylon monofilaments (SWMs) and by motor nerve conduction velocity (MNCV). These 2 physiological indicators and histology of sciatic nerves were compared among different groups.

Results The SWM measurements improved toward normal values after decompression. The SWM value was significantly lower (more normal) in the DSNC groups than in the DSND group (P < 0.05). The MNCV was 53.7 ± 0.8 m/s in the CR group, whereas it was 28.4 ± 1.0 m/s in the DSNC group (P < 0.001). Six weeks after decompression, the MNCV was significantly faster than that in the DSNC group (P < 0.001). Histological examination demonstrated chronic nerve compression, which responded toward normal after decompression, but with degree of myelination never recovering to normal.

Conclusions Chronic compression of the diabetic sciatic nerve has measureable negative effects on sciatic nerve motor nerve function, associated with a decline of touch/pressure threshold and degeneration of myelin sheath and axon. Nerve decompression surgery can reverse these effects and partially restore nerve function.

From the *Department of Orthopedics, Zhongshan Hospital, Fudan University, Shanghai, China;

Department of Plastic Surgery, Johns Hopkins University, Baltimore, MD; and

The Joseph M. Still Burn and Reconstructive Center, Jackson, MS.

Received April 1, 2018, and accepted for publication, after revision August 8, 2018.

This work was supported by a grant from the Zhongshan hospital personnel training program (no. 2015ZSYXGG22). All authors listed above have contributed to the work. The experiments were conceived and designed by Z.C., F.Z., W.C.L., and A.L.D. and performed by J.H., Y.T., Z.D., and Z.C. The data were analyzed by J.H. and Y.T., and J.H. wrote the article.

Conflicts of interest and sources of funding: none declared.

J.H. and Y.T. did the same work, and they should be listed as co–first authors.

Reprints: Zenggan Chen, MD, PhD, Department of Orthopedics, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, China, 200032. E-mail: chen.zenggan@zs-hospital.sh.cn; Feng Zhang, Department of Orthopedics, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, China, 200032. E-mail: zhang.feng2@zs-hospital.sh.cn.

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