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J. Nishimoto1,2, Y. Minegishi2,3, M. Uto4, N. Kanemura2
1Saitama Medical Center, Saitama Medical University, Rehabilitation, Kawagoe, Japan, 2Saitama Prefectural University, Graduate Course of Health and Social Service, Koshigaya, Japan, 3Japan Society for the Promotion of Science, Research Fellowship for Young Scientists, Tokyo, Japan, 4Tanaka Family Clinic, Rehabilitation, Saitama, Japan
Background: Although nerve regeneration occurs after peripheral nerve injury, clinically proximal peripheral nerve injury results in a poor outcome, and long-term residual motor dysfunction. Many rehabilitation studies have been conducted after peripheral nerve injury. The focus has been on preventing secondary disorders through physical therapy, such as joint mobility exercises, orthotic therapy, and electrical stimulation. In recent years, there have been scattered reports that exercise promotes peripheral nerve regeneration. However, the impact of exercise on the recovery of motor function is not clear.
Purpose: In this study, we hypothesized that exercise also promotes the recovery of motor function after peripheral nerve injury, and we aimed to examine this hypothesis in an animal model.
Methods: A total of 24 ten-week-old ICR mice weighing 42.4 ± 2.8 g were used in this study. Mice were randomly divided into the following three groups: (1) a sham group (n=8; these mice did not undergo sciatic nerve crush), (2) a SC group (n=8; the right sciatic nerve was crushed in these mice), and (3) a SCex group (n=8; these mice were subjected to treadmill exercises after right sciatic nerve crush). The surgical procedure was followed by the administration of a combination of anesthetics (medetomidine, 0.75 mg/kg, midazolam, 4.0 mg/kg, butorphanol, 5.0 mg/kg), after which the nerve was exposed in the middle of the thigh. The nerve was then crushed with forceps at 100 N for 3 minutes. Exercises were performed five times a week for one hour a day at a speed of 10 m/min using a treadmill device. The Sciatic Functional Index (SFI) and the Ladder rung walking test (LRWT) were used to assess motor function. The LRWT was assessed in two ways: using a 3-mm diameter metal rod, walking 2 m at equal intervals (1 cm apart) or walking irregularly (0.5-2 cm apart). Motor function assessment was performed at 3day, 1, 2, 3, 4 weeks postoperatively. SFI, and LRWT were compared using a one-way analysis of variance, and post hoc analyses were conducted using multiple comparisons by Tukey's method. p <0.05 was considered statistically significant for all analyses and all values were two-tailed.
Results: At 1, 2, 3, and 4 weeks postoperatively, the SCex group had significantly better SFI and LRWT scores than the SC group (p<0.01). Both SFI and LRWT scores were significantly higher in the Sham group than in the SC group at 3 days, 1, 2, 3, and 4 weeks after the operation (p<0.01). In addition, both SFI and LRWT scores were significantly higher in the Sham group than in the SCex group at 3 days, 1, 2, and 3 weeks after the operation (p<0.01).
Conclusion(s): Exercise after sciatic nerve crush improved the SFI and LRWT scores.
Implications: Previous studies have reported recovery of the SFI score after physical therapy, which included low response level lasers and electrical stimulation. Furthermore, previous studies have not revealed the impact of exercise on SFI and LRWT. The results of this study suggest that a combination of exercise and physical therapy, such as laser, may further restore motor function.
Funding, acknowledgements: No funding source.
Keywords: exercise, motor function, sciatic nerve crush
Topic: Disability & rehabilitation
Did this work require ethics approval? Yes
Institution: Saitama Prefectural University
Committee: Ethics Committee of Saitama Prefectural University
Ethics number: 44802
All authors, affiliations and abstracts have been published as submitted.
