Lasers in Medical Science

, Volume 27, Issue 2, pp 479–486

Functional and morphometric differences between the early and delayed use of phototherapy in crushed median nerves of rats

Authors

    • Department of PhysiotherapyFederal University of Jequitinhonha and Mucuri Valleys
  • Carla Adelino Suaid
    • Department of Surgery and Anatomy, Medical School of Ribeirão PretoUniversity of São Paulo
  • Murilo Xavier
    • Department of PhysiotherapyFederal University of Jequitinhonha and Mucuri Valleys
  • Fernanda Yamane
    • Department of Neuroscience, Medical School of Ribeirão PretoUniversity of São Paulo
Original Article

DOI: 10.1007/s10103-011-0972-4

Cite this article as:
Santos, A.P., Suaid, C.A., Xavier, M. et al. Lasers Med Sci (2012) 27: 479. doi:10.1007/s10103-011-0972-4

Abstract

This study evaluated the functional and quantitative differences between the early and delayed use of phototherapy in crushed median nerves. After a crush injury, low-level laser therapy (GaAs) was applied transcutaneously at the injury site, 3 min daily, with a frequency of five treatments per week for 2 weeks. In the early group, the first laser treatment started immediately after surgery, and in the delayed group, after 7 days. The grasping test was used for functional evaluation of the median nerve, before, 10, and 21 days after surgery, when the rats were killed. Three segments of the median nerve were analyzed histomorphometrically by light microscopy and computer analysis. The following features were observed: myelinated fiber and axon diameters, myelin sheath area, g-ratio, density and number of myelinated fibers, and area and number of capillaries. In the proximal segment (site of crush), the nerves of animals submitted to early and delayed treatment showed myelinated fiber diameter and myelin sheath area significantly larger compared to the untreated group. In the distal segment, the myelin sheath area was significantly smaller in the untreated animals compared to the delayed group. The untreated, early, and delayed groups presented a 50, 57, and 81% degree of functional recovery, respectively, at 21 days after injury, with a significant difference between the untreated and delayed groups. The results suggest that the nerves irradiated with low-power laser exhibit myelinated fibers of greater diameter and a better recovery of function.

Keywords

Median nerveCrush injuryMorphometryGrasping testLow-power laser

Copyright information

© Springer-Verlag London Ltd 2011