ABSTRACT
BACKGROUND:
During maxillofacial
trauma or
oral cancer surgery,
peripheral nerve might be damaged by
traction injury. The purpose of this study was to evaluate functional and histomorphometric changes after
traction nerve
injury in the
sciatic nerve of a
rat model.
METHODS:
A total of 24
Sprague-Dawley rats were equally divided into three groups unstretched (sham/control, group A), stretched with 0.7N (group B) and 1.5N (group C).
Traction injury was performed for 10 min in B and C groups. Functional recovery of the
sciatic nerve was evaluated by
walking track analysis,
toe spread test, and pinprick test 2 weeks after
injury. The weight of gastrocnemius
muscles of both sides was measured to evaluate weight ratio (ipsilateral/contralateral). Total number of
axons,
axon fiber size,
myelin thickness, G-ratio,
axon number/mm2, diameter of fiber, changes of longitudinal width, and formation of the
edema and
hematoma were evaluated by
transmission electron microscopy.
RESULTS:
The sciatic function indexes were -11.48±4.0, -15.11±14.84, and -49.12±35.42 for groups A, B, and C, respectively. Pinprick test showed 3.0, 2.86±0.38, and 1.38±0.52 for A, B, and group C.
Muscle weight ratios were 0.98±0.13 for group A, 0.70±0.10 for group B, and 0.54±0.05 for group C. There were significant differences in
toe spread test, pinprick test, and
muscle weight ratio between
control group and experimental group (p<0.001). In the experimental group, fiber number, fiber size, G-ratio, fiber number/mm2,
myelin thickness, diameter of fiber, and longitudinal width were decreased with statistical significance.
CONCLUSION:
The present study demonstrated that the nerve
traction injury in the
rat sciatic nerve damaged the motor and
sensory function and axonal integrity. The amount of functional nerve damage was proportional to the amount of
traction power and dependent on the initial
tensile strengths (0.7N and 1.5N).